General provisions operation of boiler plants
The operation of steam and hot water boilers is carried out in accordance with the Rules for the Design and Safe Operation of Steam and Hot Water Boilers of Rostechnadzor, the Rules for Technical Operation power stations and networks (PTE), Safety Rules for gas distribution and gas consumption systems, instructions from manufacturers, local instructions: official ones, defining the rights and responsibilities of personnel; technical, which determine the conditions for the safe and economical operation of boilers and their individual elements during different periods of operation; on safety precautions, which indicate the necessary measures to ensure conditions safe work personnel; emergency ones, which indicate measures to prevent the development and liquidation of accidents; other regulatory and technical documents.
The rules for the design and safe operation of steam and water-heating boilers apply to steam boiler units with a pressure of more than 0.07 MPa and water-heating boiler units with a water temperature of at least 115 °C. They define the requirements for the design, manufacture, repair and material of the specified equipment, indicate the nomenclature and quantity of fittings, measuring equipment, protection, automation devices, and also provide requirements for service equipment.
The boiler plant is a very dangerous production facility and therefore it is subject to the requirements of Federal Laws dated July 21, 1997 No. 116-FZ (as amended by Federal Laws dated August 7, 2000 No. 122-FZ, January 10, 2003 No. 15-FZ, August 22, 2004 No. 122 -FZ, 05/09/2005 No. 45-FZ, 12/18/2006 No. 232-FZ) “On industrial safety production facilities" and dated December 27, 2002 No. 184-FZ "On technical regulation".
The Federal Law “On Industrial Safety of Production Facilities” defines the legal and economic basis for ensuring the safe operation of hazardous equipment; natural facilities and is aimed at preventing accidents at hazardous production facilities and ensuring the readiness of the organization operating hazardous production facilities to localize and eliminate the consequences of these possible accidents.
The Federal Law “On Technical Regulation” regulates relations arising in the development, adoption, application and implementation of mandatory requirements for products, production processes, operation, storage, transportation, sales and disposal. The law sets out the requirements for the content and application of technical regulations, principles of standardization, rules for the development and approval of standards, organization of mandatory certification, accreditation of certification bodies and state control over compliance with technical regulations.
In accordance with the Federal Law “On Industrial Safety of Production Facilities”, the basis of industrial safety is licensing of activities (design, construction, operation, reconstruction, manufacturing, installation, adjustment, repair, etc.) in the field of industrial safety; certification technical devices, used on dangerous production facility; examination of industrial safety of technical devices; industrial safety requirements for the operation of a hazardous production facility (ensuring that the hazardous production facility is staffed with workers who meet the relevant qualification requirements; the presence at the hazardous production facility of regulatory legal acts and regulatory technical documents establishing the rules for conducting work at a hazardous production facility; organization and implementation of production control over compliance with industrial safety requirements; ensuring the availability and operation of the necessary equipment and control systems production processes; ensuring the examination of industrial safety of buildings, diagnostics and testing of technical devices in established deadlines etc.).
The operation of steam and hot water boilers and boiler equipment consists of servicing boiler units and auxiliary equipment (smoke exhausters, fans, pumps, flues and chimneys).
In accordance with the PTE, boiler room personnel must ensure reliable operation all main and auxiliary equipment, the ability to achieve nominal performance, steam and water parameters. The PTE sets out the basic requirements for the operation of boilers and auxiliary equipment (kindling, shutdowns, main operating modes, conditions for immediate shutdown of equipment).
The instructions provide technical specifications and a detailed description of the equipment, procedure and timing. maintenance, control, repairs; Limit values and deviations of parameters, recommendations for safe maintenance and rules for the safe work of maintenance personnel are given.
The complexity of the equipment makes high demands on boiler room operating personnel. All newly hired workers who do not have a production specialty or are changing it are required to undergo vocational and technical training to the extent of the qualification requirements in accordance with the Unified Tariff and Qualification Reference Book (UTKS). Training of workers is carried out, as a rule, in training centers and other institutions of basic vocational maintenance, control, and repairs; Limit values of nic education are given.
Persons who have received theoretical and industrial training undergo an internship and knowledge testing at the enterprises where they will work. During the internship, boiler room equipment, production instructions and operating diagrams, safety regulations and fire safety, Rostechnadzor rules, job descriptions. After this, the trainee may be allowed to perform duplicate duties at the workplace under the supervision and guidance of an experienced employee with a duplication period of at least 10 work shifts. Particular attention is paid to the problems of professional suitability, physiological and psychological preparedness of the employee. People who have reached the age of 18 and have a positive medical report are hired. Subsequently, a medical examination is carried out once every two years.
Service personnel need to constantly deepen and improve their knowledge and improve their skills. To achieve this, work must be organized to improve the qualifications of personnel. Operators undergo an annual knowledge test safe methods labor and methods of performing work, and once every two years - according to PTE, Fire Safety Rules, production and job descriptions.
1.2. Preparing the boiler unit and auxiliary equipment for start-up
Putting a boiler into operation is a complex process that is carried out after installation of the boiler when putting it into operation, as well as after reconstruction, repair, planned and unscheduled shutdowns of the boiler. Carrying out the start-up process involves the precise execution, strictly according to instructions, of a large number of various actions while observing a strict distribution of responsibilities of personnel, coordination of their actions in conditions of high efficiency and technical discipline. The most qualified personnel are allowed to start up the boiler. The shift manager or senior operator supervises the boiler startup operations.
Starting the boiler is associated with its lighting, which is preceded by operations for a detailed inspection of the unit in order to check its serviceability and readiness for operation. The firebox, radiation and convective heating surfaces, steam superheater, water economizer, air heater, lining, explosion valves, casing, manifolds, pipelines and fittings, gas and fuel oil pipelines, burners, suspensions, supports, protective and spacer elements are subject to inspection. When inspecting the heating surfaces in the boiler, attention is paid to the presence of cracks, fistulas, bulges, traces of corrosion and contamination of pipes. All foreign objects and debris must be removed from the firebox and gas ducts, and the gas-air path openings must be tightly closed.
The removal of plugs on the gas pipeline, steam, water, purge and drain lines is checked; serviceability of drives and ease of movement of dampers, axial guide vanes of smoke exhausters and fans; controllability from the main panel; grounding of electric motors; presence of oil in bearings; supply of water for their cooling; the presence of enclosing covers on rotating mechanisms and freedom of their rotation. After inspecting the auxiliary equipment, their mechanisms should be turned on idle, and there should be no knocking, vibration, or excessive heating of bearings or electric motors.
The serviceability of all water and steam fittings of the boiler, water indicating devices, and the serviceability of remote drives are checked. The operation of ignition protective devices, the serviceability of safety valves, as well as the serviceability and readiness to turn on the control system are checked. measuring instruments, automatic regulators, interlocks, protections, operational communications, lighting, fire extinguishing equipment.
Malfunctions identified during the inspection must be eliminated before starting the boiler. If the protections acting to stop the boiler are faulty, starting it is prohibited.
After checking the equipment, preparations begin for the start-up of the gas-air and water-steam paths, the kindling, steam and gas-oil facilities, boiler blow-off, etc. General and individual shut-off dampers are opened (on air ducts, burners, nozzles), the guide vanes of fans, smoke exhausters, and regulating air dampers are closed. .
Before filling the boiler with water, check the closure of the main steam shut-off valve and all drain and purge valves; the vents of the drum and water economizer open; water indicator glasses, water valves and a pair of lowered level indicators are switched into working position; the pressure gauge on the drum must be in working condition; the shut-off devices on the supply pipelines in front of the water economizer are opened; the adjusting devices are checked - they must be tightly closed.
For boilers with a cast iron economizer, a direct flow gate opens to allow SG to pass past the economizer. In the absence of a bypass flue, water must be continuously pumped through the economizer and directed along the discharge line to the deaerator. For boilers with a steel economizer, the valve on the recirculation line opens.
To supply water to the boiler, it is necessary to open the feed valve and fill the water economizer with water; When water appears, close the vent on the economizer outlet manifold. The boiler is filled with water to the firing level.
To avoid violation of the density of rolling joints and thermal deformations from uneven heating, it is not allowed to fill the boiler with water with a temperature above 90 °C in the summer and 50...60 °C in the summer. winter period.
After filling the boiler with water, it is necessary to ensure the tightness of the fittings by feeling the drainage pipes. If within 0.5 hours after filling the boiler with water with the feed valve closed, there is no decrease or increase in the water level in the boiler drum, you can continue operations to prepare the boiler for start-up. If there is a device for steam heating of the lower drum, the steam supply from the operating boilers opens and the water in the boiler is heated to a temperature of 90... 100 °C.
Before lighting a gas-fired boiler from a cold state, a pre-start check is carried out for the tightness of the shut-off devices in front of the burners and the safety shut-off valves (control pressure testing). The procedure and methods for pre-launch checks are established production instructions. Automatic and block gas burners, which are currently equipped with many boiler units, are equipped with devices for automatic leak testing.
In preparation for lighting a boiler operating on gas, the gas pipeline to the shut-off devices on the burners must be purged with gas through purge candles. To do this, it is necessary to open the shut-off valve to the passage and slightly open the shut-off device on the lower side, and for the time specified in the production instructions, purge the gas pipeline through the purge plug.
The end of the purge is determined using a gas analyzer based on the oxygen content in the gas pipeline. In a purged gas pipeline, the oxygen content should not exceed 1%.
Before turning on gas burners or kindling fuel oil nozzles, it is necessary to ventilate the firebox and flues, first using natural draft and then forced. At natural ventilation completely open the gas path dampers and dampers that regulate the air supply to the burners. For forced ventilation turn on the smoke exhauster, and then the fan, and for 10... 15 minutes, with them working together, the smoke tract of the boiler unit is ventilated.
6.3. Starting the steam boiler unit
Putting a steam boiler unit into operation can only be carried out by written order from the head of the boiler room. The sequence of operations when starting up boilers is determined by their thermal state after the corresponding downtime (for repairs or in reserve). Depending on the degree of cooling of the boiler unit after the previous shutdown, starts from cold, uncooled, hot states and from hot reserve are distinguished. Each type of launch is characterized by a certain technology. Starting from a cold state is carried out 3...4 days or more after shutdown when the boiler unit is completely cooled and there is no pressure in it. In this case, the start-up, starting from the lowest level of temperatures and pressures in the boiler unit, has the longest duration.
Reliability ignition of gas burners with forced air supply depends mainly on the density of the dampers that regulate the air supply to the burner. Ignition of each of the installed burners must be carried out from an individual igniter installed in the ignition hole. The stability of the igniter flame depends on the vacuum in the furnace and the density of the gate that regulates the air supply to the burner. In connection with this, before inserting the igniter into the firebox, it is necessary to ensure that the gate regulating the air supply is properly closed and adjust the vacuum in the upper part of the furnace in accordance with the recommended for kindling meaning. The pilot flame should be located to the side and in close proximity to or above the embrasure.
When the igniter is operating steadily, gas is supplied to the burner smoothly so that the gas pressure does not exceed 10... 15% of the pump pressure. Ignition of the gas leaving the burner must occur immediately. If the gas coming out of the burner does not ignite immediately, it is necessary to quickly stop its supply to the burner and igniter and ventilate it for 10...15 minutes to remove gas from the firebox. Re-ignition of the burner is permitted only after the reasons preventing its normal start-up have been eliminated.
After ignition of the gas leaving the burner, the air supply is adjusted so that the luminosity of the torch decreases, but does not separate from the burner. To increase burner productivity, first increase the gas pressure by 10... 15%, and then the air pressure accordingly, after which the set vacuum value in the furnace is restored. When the first burner is operating stable, proceed to ignite the remaining burners in sequence.
For ignition of boilers operating on fuel oil after the ventilation of the firebox and flues is completed (while the smoke exhauster and fans are operating), the fuel oil nozzles are ignited one by one. So, for example, before igniting a nozzle with steam spraying of fuel oil, it is necessary to completely close the hatches and peepholes, stop the air supply to the nozzle, adjust the vacuum in the upper part of the furnace, setting it equal to 10...20 Pa, and make sure that the required fuel oil heating temperature has been established . Then you should insert an oil pilot torch into the pilot hole. When the torch is burning steadily, a little air and steam is first supplied to the nozzle, and then fuel oil is supplied by gradually opening the control valve. When fuel oil ignites, it is necessary to regulate its combustion by changing the supply of fuel oil, steam and air. When the fuel oil burns steadily, the ignition torch is removed.
When starting up the boiler, special attention is paid to maintaining the specified temperature of the metal of thick-walled parts (drum, collectors, steam pipes, fittings) and the rate of their heating. The choice of heating technology depends on their initial state. To ensure uniform temperatures around the perimeter of the drum, especially its upper and lower parts, steam heating is used, for which appropriate steam lines are installed in the drum in the lower part.
When lighting the boiler, the water level in the drum is monitored using water indicators on the drum and lower level indicators. On boilers with a pressure of up to 4 MPa, water indicator columns are purged at a pressure of 0.1 MPa and again before turning the boiler into the general steam line. As the pressure rises, the water level in the drum rises. If the water level exceeds the permissible limit, it is necessary to drain some of the water from the boiler through the periodic blowdown line. When the water level drops due to purging of the boiler unit and superheater, it is necessary to replenish the boiler with water.
During the process of lighting the boiler from a cold state, it is necessary to monitor the thermal expansion of the screens, drum, collectors and pipelines according to the benchmarks installed on them. If the heating of any screen lags, it should be blown through the drains of the lower collectors for 25 s.
When the steam pressure in the boiler unit increases above atmospheric pressure, steam will begin to escape from the air vents, after which it is necessary to close the air vent valves and blow out the boiler pressure gauges. Warming up of the connecting steam lines from the boiler to the main steam line is carried out simultaneously with the heating of the boiler. During heating of the steam line, water hammer should not be allowed to occur, and if it occurs, it is necessary to stop the heating, find out the cause of the water hammer and eliminate it.
The boiler unit is included in the common steam line at a temperature close to the design one, and when the pressure in it reaches 0.05...0.10 MPa less than the pressure in the common steam line. The shut-off devices on the steam line are opened very slowly to avoid water hammer. If, however, while switching on the boiler unit to the common steam line, shocks and hydraulic shocks occur, the switching procedure is immediately suspended, the combustion in the furnace is weakened by opening the valve, the blowing of the superheater is increased and the drainage of the steam line is increased.
6.4. Boiler installation maintenance during operation
Maintenance of a boiler installation is a process that includes monitoring the operation of the installation, controlling its organs and auxiliary mechanisms in order to regulate the working process in the boiler.
To control the operation, the boiler is equipped with instrumentation located on the unit itself and on the heat shield. To regulate operation, the boiler unit has controls with drives directly at the installation site or with remote drives. Thus, remote control via electric drives is carried out from the boiler control panel.
The most important maintenance tasks steam boiler units are maintaining the specified steam pressure and productivity (load) of the boiler in accordance with the instructions of the regime map, an approximate example of which is given in table. 6.1, as well as maintaining a given temperature of superheated steam, uniform supply of water to the boiler unit, maintaining a normal water level in the drum, ensuring normal purity of saturated steam, caring for all equipment of the boiler unit.
Table 6.1
Approximate operating schedule of the steam boiler unit DKVR-10-13
"I affirm" Chief Engineer enterprises
Parameter | measurements | Steam capacity, t/h |
|||
Steam pressure in the boiler drum | |||||
Number of working burners | |||||
Gas pressure in front of the burners | |||||
Primary air pressure before burners | |||||
Secondary air pressure before burners | |||||
Vacuum in the boiler furnace | |||||
Feed water temperature | |||||
Feed water pressure | |||||
Excess air coefficient behind the boiler unit | |||||
Flue gas temperature | |||||
Heat loss with flue gases | |||||
Heat loss from chemical incomplete combustion | |||||
Heat loss through external fences | |||||
Boiler unit gross efficiency | |||||
Heat consumption for own needs | |||||
Boiler unit net efficiency | |||||
Fuel consumption | |||||
Note. Type of burners - gas-oil type GMG-2.5.
The regime map was drawn up
Position of commissioning organization employee
When working hot water boiler unit it is necessary to provide a temperature schedule for the supply of thermal energy (Table 6.2), which guides the operator in his work when establishing the operating parameters of the installation.
Maintaining steam pressure and boiler unit performance. Depending on the operating mode of the boiler room, the main equipment can operate for a more or less long time at constant (basic) mode. A violation of the stationary regime can be caused by a change in heat release in the furnace and water supply, as well as by a load transfer from one boiler unit to another.
The main task of the personnel servicing the boiler is to maintain the most economical fuel combustion modes, which mainly determines the thermal efficiency of the boiler. Thus, the maximum efficiency of a boiler unit operating on gaseous and liquid fuels is achieved with minimal total heat losses from flue gases and from chemical incomplete combustion. Heat losses with flue gases depend on the excess air coefficient in the furnace, the level of air suction through the boiler flues and the temperature of the flue gases, and heat losses from chemical incomplete combustion depend on the excess air coefficient at at the exit from the furnace and on the distribution of air and gas among the burners .
Thus, when servicing a boiler unit, the operator must monitor the temperature and excess air coefficient aug in the flue gases at the outlet of the boiler unit (in terms of O2 or CO2 content), gas and air pressure in front of the burners. To obtain the greatest efficiency of operation of the boiler unit, it is necessary to maintain the combustion mode in accordance with the regime map, which is compiled based on the results of special tests of the boiler, when the highest efficiency is determined for each of the loads under study.
Maintaining normal steam pressure in the boiler is carried out by regulating the operation of the furnace.
Table 6.2 Approximate temperature schedule for heat supply
An increase in steam pressure above normal indicates excessive steam production of the boiler unit and to reduce it, it is necessary to reduce the supply of gas and air to the furnace. On the contrary, a decrease in steam pressure indicates insufficient steam production of the boiler unit, and to increase it it is necessary to increase the supply of gas and air. Deviations in steam pressure are caused by changes in steam consumption at the consumer, the amount of gas supplied to the furnace and the temperature of the feed water. Consequently, the regulation of steam pressure in the boiler unit is directly related to the regulation of steam production and is carried out by changing the flow of fuel and air supplied to the furnace and establishing the proper draft.
During operation of the boiler unit, visual observation of the combustion process in the furnace through peepers is necessary. Based on the results of observing the flare, certain decisions are made in order to achieve good and proper combustion. Signs good burning: the torch evenly fills the combustion chamber; a certain color of the torch and its length (depending on the type of burners); combustion must end in the combustion chamber, the end of the torch must be clean.
Maintaining normal steam temperature. When the boiler operates with a constant load over time, deviations of the superheated steam temperature from the average value are small and regulation of its temperature is practically not required.
The need to regulate the temperature of superheated steam arises when the optimal combustion mode is established or the boiler load changes. An increase in the temperature of superheated steam can occur due to an increase in the boiler load; excess air in the firebox; lowering the temperature of the feed water; reducing the flow of cooling water through the desuperheater. If the capacity of the desuperheater is already completely exhausted, and the temperature of the superheated steam is higher than normal, then it is necessary to reduce the excess air in the furnace to an acceptable limit; reduce saturated steam extraction; reduce the load on the boiler unit.
Supplying the boiler unit with water. When the boiler unit is operating, it is necessary to maintain its normal water supply, i.e. ensure material balance of water and steam. The boiler water supply is regulated automatically or manually. Automatic control ensures uniform water supply to the boiler in accordance with the steam flow and maintains the specified water level in the drum.
The operator monitors the correct operation of the boiler water supply regulators using instruments indicating water level in the drum (water gauge glasses, lowered level indicators). The water in the water-indicating columns should constantly fluctuate slightly around the normal level (at the middle of the glass height). A completely calm water level in the columns may be a sign of clogging of the water meter glass tubes. The level should not be allowed to approach the limit (upper and lower) positions in order to avoid the level being lost from the visible zone of the water meter glass.
Water mode of the boiler unit. The operation of the boiler unit without damage to its elements due to deposits of scale, sludge and an increase in the alkalinity of the boiler water to dangerous limits is ensured by the water regime. Maintaining the specified salinity content of the boiler water is achieved by continuous blowdown. To remove sludge from the lower points, the unit is periodically purged (draining boiler water).
With continuous blowing, a significant amount of heat is lost. At a steam pressure of 1... 1.3 MPa, every 1% of purging, the heat of which is not used, increases fuel consumption by approximately 0.3%. The use of continuous blowing heat is possible in specially installed separators for the production of secondary steam. To regulate the amount of continuous blowing, needle valves are used. From the common continuous blowdown collector, water enters the separator, where, as a result of a decrease in pressure, part of it boils. The resulting steam is sent to the deaerator, and the water is sent to heat the raw water entering the chemical water treatment area.
The timing and duration of periodic blowdowns are established by the production instructions. Before such purging, make sure that proper work feed pumps, there is water in the feed tanks, feed the boiler to the upper level according to the water indicator glass. Blowing is carried out in the following order: first, the second valve along the line is opened, and then the first one, and after the blowing pipeline has warmed up, the actual blowing is carried out, during which the water level in the boiler drum is continuously monitored using a water meter glass. When there is a hydraulic shock in the pipeline, immediately close the purge valve until the knocking in the pipeline stops, then the valve is gradually opened again. At the end of the purging, the valves are closed - first the first one along the water flow, and then the second one.
Maintenance of boiler unit equipment. During the operation of the boiler unit, it is necessary to monitor the condition of the shut-off and control valves, tighten the seals if they become loose and allow water or steam to pass through. If the gaskets are faulty or the fittings are leaking, repairs are prescribed. The serviceability of safety valves is checked every shift by carefully opening them (“exploding”).
The serviceability of the pressure gauge is checked every shift by setting its needle to “zero” (“zero landing”) by slowly closing the three-way valve of the pressure gauge and connecting it to the atmosphere. Having made sure that the pressure gauge needle has gone to “zero”, carefully return the three-way valve to the operating position, trying not to let water out of the siphon tube in order to avoid overheating of the spring and damage to the pressure gauge. To check the pressure gauge, its readings are periodically (at least once every 6 months) compared with the readings of the control pressure gauge.
The proper operation of the water-indicating columns on the drum is checked by blowing them in the following order: the blow-off valve is opened, and the water-meter glass, water and steam tubes are simultaneously blown out; the water tap is closed and the steam pipe and water meter glass are purged; the water tap opens and the steam tap closes - the water tube and water meter glass are blown out; the steam valve opens and the purge valve closes, i.e. the water level in the water meter glass is set to the working position, and the water level in the drum is checked.
All blowing actions should be carried out slowly, with eye protection with goggles and always with gloves on.
During operation of the boiler, it is necessary to carefully monitor the density of gas fittings and gas pipelines. Periodically, at least once per shift, check for gas leaks based on the methane content in the room; If there is more than 1% methane in the air, identify leaks and take measures to eliminate them.
It is necessary to monitor the condition of the boiler lining, the density of manholes and hatches, inspecting them while walking around, and also, using the oxygen meter readings, monitor the possibility of leaks along the tract. You should also, while opening the hatches, listen to the sounds in the firebox and gas ducts to identify possible damage to the pipes, which are accompanied by increased noise.
It is necessary to periodically check the operation of smoke exhausters, fans, and boiler pumps. The temperature of electric motor stators and bearings is checked by touch; the noise of rotating machines should be monotonous, without sharp impacts indicating contact, and without vibrations, which are also checked by touch at the base of the bearings and support plates; The nuts of the foundation bolts of electric motors, pumps, smoke exhausters and fans must be tightly tightened.
Every 2 hours it is necessary to record the readings of instrumentation in a shift log.
Features of servicing hot water boilers. When operating a hot water boiler, the water temperature at the boiler inlet must be higher than the dew point temperature, i.e., at least 60 °C. This is achieved by mixing the water leaving the boiler with the return network water, i.e. by recirculating hot water, which is provided for by the scheme for connecting the water heating boiler to the network.
Hot water from the boiler outlet manifold is supplied by a recirculation pump to the inlet manifold and, mixing with return network water, heats it up. The specified temperature of the water and heating network is achieved by directing the return flow into it along the jumper. When regulating the flow of water supplied for recirculation, it is necessary to ensure that the flow of water through the hot water boiler is always greater than the minimum allowable under boiling conditions.
6.5. Scheduled shutdown of the boiler unit
The planned shutdown of the boiler unit is carried out by written order of the head of the boiler room. The shutdown technology, volume and sequence of operations are determined by the type of boiler unit, the fuel used and the type of shutdown. According to the final thermal state of the boiler unit, there are two types of shutdowns - without cooling the equipment and with its cooling. Shutdown without cooldown carried out when putting the boiler into hot reserve and to perform minor work, usually on the outside of the boiler. Cooldown stop produced for the purpose of fulfilling repair work increased duration, and the completeness of cooling depends on the type of intended repair.
At the boiler is in hot reserve it is necessary to take measures to maintain pressure in it for a longer time and maximize the accumulation of heat in the equipment. To do this, after ventilating the firebox and flues, the gas-air path is sealed by closing the dampers and guide devices of smoke exhausters and blower fans. It is prohibited to keep the boiler unit in hot reserve without disconnecting it from the steam line. To maintain pressure in the boiler, periodic heating is allowed. When the boiler is in hot standby, its duty personnel must be at their workplaces.
At boiler shutdown it is necessary to reduce the supply of fuel and blast, maintaining a vacuum in the furnace; In this case, it is necessary to monitor the water level in the drum using the water indicator columns. To reduce the supply of gaseous or liquid fuel, the air pressure is gradually reduced, and then the gas or fuel oil pressure in front of the burners, maintaining the required vacuum at the outlet of the furnace. When the maximum minimum fuel pressure values are reached, the burners are extinguished one by one.
After stopping the fuel supply to the boiler, close the main steam valve, i.e. disconnect the boiler from the steam line and open the superheater purge. For a certain time, in accordance with the production instructions, the firebox and flue ducts are ventilated, after which the fans are stopped, and then the smoke exhauster, and the smoke dampers and blades of the axial guide vanes of the smoke exhausters and fans are closed.
Fill the boiler drum with water to the upper mark in the water indicator column and maintain this level until the water is drained. Draining water from a stopped drum boiler is permitted after the pressure in it has been reduced to atmospheric pressure. After stopping the boiler, it is not allowed to open hatches and manholes until it cools down.
In winter, in a boiler filled with water, in order to avoid defrosting, careful monitoring of the density of the gas-air path, heating surfaces and their purge and drain lines, heaters, impulse lines and sensors of instrumentation and automation must be established. The temperature inside the furnace and flues should be above 0 °C, for which the furnace and flues are periodically heated by turning on fuel oil nozzles or by supplying hot air from neighboring boilers, and the density of dampers, manholes and hatches is monitored. On hot water boilers, water circulation through the boiler must be ensured.
6.6. Emergency shutdown of the boiler unit
During operation of the boiler unit, damage may occur in it, problems may arise that create dangerous situations, fraught with failure of equipment or the boiler unit as a whole, destruction with large material losses and human casualties. Elimination of detected violations and defects is possible taking into account the damage without stopping the boiler unit or with mandatory immediate shutdown.
The basis for the correct conduct of emergency response operations is the preservation of equipment and the prevention of major destruction (due to incorrect actions of personnel or delays in emergency response), as well as eliminating the possibility of injury to personnel. Any equipment that has defects that pose a threat to the lives of personnel must be stopped immediately. If an accident occurs at the junction of two shifts, the working personnel of the receiving shift are involved in the liquidation of the accident and carry out the orders of the personnel of the shift liquidating the accident. Repair personnel and personnel from other workshops may be involved in eliminating the accident.
The technology for emergency shutdown of a boiler unit is determined by the type of accident and the moment of establishing its causes. Initially, until the cause of the accident is determined, but not more than for 10 minutes, the shutdown is carried out with the minimum possible cooling of the equipment (while maintaining the operating pressure and sealing the gas-air path). If the cause of the accident is identified and eliminated within 10 minutes, then the boiler unit is started from the hot standby state. If within this period the cause of the accident is not identified, then, as in the case of equipment breakdown, the boiler unit is shut down.
Mandatory immediate shutdown of the boiler unit personnel carry out in case of an unacceptable increase or decrease in the water level in the drum, as well as failure of indicating devices (caused by malfunctions of power regulators, damage to control valves, thermal control devices, protection, automation, loss of power, etc.); failures of all feedwater flow meters; stopping all feed pumps; an unacceptable increase in pressure in the steam-water path and failure of at least one safety valve; rupture of steam-water path pipes or the appearance of cracks, swellings, gaps in the welds of the main elements of the boiler, in steam pipelines, fittings.
In addition, boilers must be stopped when combustion stops and there is an unacceptable decrease or increase in gas pressure and a decrease in fuel oil pressure behind the control valve; in case of an unacceptable decrease in air flow in front of the burners and vacuum in the boiler furnace caused by stopping all fans and smoke exhausters, respectively; explosions in the furnace, in gas ducts; warming up red hot load-bearing beams frame and lining collapses; fire threatening personnel, equipment, system power remote control shut-off valves and corresponding protection systems; loss of voltage in the lines of remote and automatic control and instrumentation.
Water heating boilers must also be stopped when the water flow and pressure in front of the boiler decrease below the minimum permissible value.
6.7. Problems and accidents in the boiler room. Damage to boiler unit elements
Accidents and malfunctions of boiler equipment cause unit downtime, which leads to undersupply of electricity and thermal energy (steam and hot water) to consumers. All cases of emergency situations, serious malfunctions in the operation of the boiler and its equipment must be dealt with by identifying the causes and considering the actions of personnel. In order to prevent possible accidents, in boiler rooms and to develop confident actions of personnel in emergency situations, emergency training is regularly carried out for maintenance personnel, during which various types of accidents are conditionally created and the work of the personnel is monitored. After such training, the work performed is analyzed and an assessment is made of the efficiency and correctness of the actions of the shift personnel.
Accidents due to overfilling and loss of water in the boiler. When the drum is significantly over-saturated boiler water together with the steam it is thrown into the superheater, from there it (if it does not have time to evaporate) can be carried into the steam line. Moving along with steam at a very high speed, water causes hydraulic shocks, which are sometimes so strong that they can cause damage to steam lines.
When there is a deep release of water in the boiler below the permissible level, the metal of the boiler and screen pipes and parts of the drums heated by hot gases overheats, as a result of which it loses its strength, becomes deformed, and sometimes breaks, and the boiler drum explodes. An explosion is usually accompanied by great destruction with serious consequences. It should be borne in mind that clogging of the connecting pipes of the drum with water indicator columns causes a distortion of the water level in the water measuring glasses; it does not correspond to the actual position of the water level in the boiler drum. In this case, clogging of the steam tap or connecting tube from the drum to this tap leads to a rapid increase in the water level in the water gauge glass, and clogging of the connecting water tube or water tap is accompanied by a slower increase in the level due to the gradual condensation of steam in the water gauge column.
In the event of a significant decrease in the water level in the boiler, i.e. If the level “falls” below the lowest permissible at normal pressure of water in the supply line and steam, it is necessary to blow through the water indicator columns and make sure that their readings are correct; check the operation of the power regulator and, if the defect is difficult to eliminate, switch to manual regulation and increase the power supply to the boiler; check the serviceability of the feed pumps and, if they are damaged, turn on the backup pumps; close the continuous blowdown valve and check the tightness of all boiler blowdown valves; check visually and audibly for leaks in seams, pipes, hatches (based on noise). If the water level continues to decrease and is already 25 mm above the lower edge of the water gauge glass, then it is necessary to carry out an emergency shutdown of the boiler unit.
When refilling the boiler, when the water level has risen to the highest permissible level at normal pressure in the boiler and in the supply line, it is necessary to blow through the water indicator columns and ensure that their readings are correct; check the operation of the automatic power regulator and, if it is faulty, switch to manual regulation and reduce the power to the boiler. If, despite the measures taken, the water level continues to rise, further reduce the boiler power supply and increase continuous blowing; Carefully open periodic blowing, but as soon as the water level begins to decrease, stop blowing.
If the water level has “gone” beyond the upper edge of the water meter glass, it is necessary to carry out an emergency shutdown of the boiler unit.
Damage to boiler and screen pipes, feed and steam pipelines. Operating experience of steam boilers shows that damage to boiler and screen pipes most often occurs due to violations of the water regime caused by unsatisfactory operation of chemical water treatment, lack of the correct phosphating regime, etc. The causes of pipe ruptures can also be excess pressure, violation of temperature conditions their work, corrosion or wear of pipes, poor manufacturing and installation, inadequacy of the materials used, etc.
Sometimes ring cracks are observed at the ends of boiler and screen pipes rolled into drums or collectors. The cause of such damage is the aggressiveness of the boiler water and significant local additional stresses due to the impossibility of free thermal expansion of pipes or collectors due to their clamping in places where they pass through the lining, etc. Ruptures of supply pipelines and main steam lines are observed much less frequently than ruptures of heating surface pipes, however, in terms of their destructive consequences, these damages are much more dangerous.
Given the increased danger of destructive actions during ruptures, it is necessary to regularly check the condition of pipelines. The inspection is carried out in accordance with the Instructions for Monitoring and Control of Metal of Pipelines and Boilers. During these inspections, timely removal of damaged sections of pipelines and their subsequent replacement must be carried out. Mostly, violations occur in bend areas, near the installation of reinforcement, in places of transitions from one thickness to another, in places of welded joints.
External signs of rupture of boiler or screen pipes are a rapid decrease in the water level in the boiler drums, despite the increased supply of water to them: a significant discrepancy between the mass of feed water entering the boiler and the mass of steam produced by the boiler, which is determined by instrument readings; strong steam noise in the furnace or boiler flues; increasing the pressure in the firebox and knocking gases out of the loose lining and peeper hatches.
Accidents and malfunctions of superheaters. The superheater is one of the least reliable elements of the boiler unit. The main type of accident in it is the burnout of the coils due to an excessive increase in the temperature of the pipe wall relative to the design value. An increase in the temperature of the coil wall is possible due to the uneven distribution of steam generator temperatures across the width of the gas duct in which the superheater is located; uneven distribution of steam across the coils; contamination of the superheater pipes with salts, which leads to a deterioration in the transfer of heat from the walls of the pipes to the steam.
Often, malfunctions are observed in the operation of the superheater, resulting in an excessive increase in the superheating temperature of the steam. The reasons for this are changes in the grade and quality of fuel; increase in boiler load; increasing the temperature of the steam generator in front of the superheater; decrease in feedwater temperature.
Accidents and malfunctions of water economizers. Damage to steel coil economizers occurs mainly due to internal and external corrosion of pipes. In addition, fistulas and ruptures are often observed in places where coils are welded, indicating unsatisfactory quality of welding work.
Internal corrosion of pipes usually occurs when the economizer is fed with non-deaerated water with a high content of oxygen or CO2. External corrosion of the economizer is more common when boilers operate on sulfur fuels. The causes of external corrosion are cooling and condensation on the walls of pipes of water vapor and sulfur dioxide contained in fuel combustion products.
Damage to cast iron finned economizers occurs due to rupture of pipes and connecting rods, as well as damage to gaskets in flange connections. Such damage can be caused by water hammer in the economizer, improper installation of gaskets, over-tightening of flanges, etc.
The first signs of failure of water economizers (pipe rupture, leak, etc.) are a sharp decrease in the water level in the boiler drum during normal operation and noise in the economizer area.
Explosions and bangs in the firebox and flues. In gas-fueled boilers, explosions in the furnace are caused by gas leaks, poor ventilation of the furnace and flues before firing and incomplete purging of gas pipelines to the burners (through candles), as well as re-ignition of gas after a torch break without sufficient re-ventilation of the furnace. These explosions tend to have severe consequences.
When burning liquid fuel, fires and explosions in the furnace and gas ducts occur when it is poorly atomized by nozzles, accompanied by the leakage of fuel oil into the embrasures and onto the walls of the firebox with its accumulation in significant quantities, as well as increased removal of soot into the flues, which appears due to poor mixing of air with fuel oil and its incomplete combustion. In the latter case, accumulation and, under certain conditions, combustion of deposits on heating surfaces occurs. In this case, an increase in gas temperature that is unusual for this surface is noted, the thrust decreases, the skin heats up, and sometimes a flame breaks out.
If a fire is detected, you should immediately stop supplying fuel, localize the fire (by turning off blower fans and smoke exhausters and tightly closing gas and air dampers) and turn on local fire extinguishing (supplying steam or water to the flue). Explosions and bangs can cause destruction of the lining and elements of the boiler unit.
Registration No. 4703
Resolution
"On approval of the Rules for Design and Safe Operation
steam and hot water boilers"
Gosgortekhnadzor of Russia decides:
1. Approve the Rules for the design and safe operation of steam and hot water boilers.
2. Submit the Rules for the Design and Safe Operation of Steam and Hot Water Boilers for state registration to the Ministry of Justice of the Russian Federation.
Head of Gosgortekhnadzor of Russia
V.M. Kulyechev
Rules for the design and safe operation of steam and hot water boilers
PB 10-574-03
I. General provisions
1.1. Purpose and scope of the Rules
1.1.1. Rules for the design and safe operation of steam and hot water boilers (hereinafter referred to as the Rules) establish requirements for the design, construction, materials, manufacture, installation, commissioning, repair and operation of steam boilers, autonomous steam superheaters and economizers with a working pressure (1) more than 0.07 MPa (0.7 kgf/cm2), hot water boilers and autonomous economizers (2) with water temperatures above 115°C.
The symbols and units of measurement used in the Rules are given in Appendix 3.
1.1.2. The rules apply to:
a) steam boilers, including boilers, as well as autonomous steam superheaters and economizers;
b) water-heating and steam-water-heating boilers;
c) energy-technological boilers: steam and water-heating boilers, including soda recovery boilers (SRK);
d) waste heat boilers (steam and hot water);
e) boilers for mobile and transportable installations and power trains;
f) steam and liquid boilers operating with high-temperature organic coolants (HOT);
g) steam and hot water pipelines within the boiler.
1.1.3. The rules do not apply to:
a) boilers, autonomous steam superheaters and economizers installed on sea and river vessels and other floating facilities (except dredges) and underwater facilities;
b) heating boilers of railway cars;
c) boilers with electric heating;
d) boilers with a volume of steam and water space of 0.001 m 3 (1 l) or less, in which the product of the operating pressure in MPa (kgf/cm 2) and the volume in m 3 (l) does not exceed 0.002 (20);
e) on thermal power equipment nuclear power plants;
f) steam superheaters for tubular furnaces of oil refining and petrochemical industries.
1.1.4. Deviations from the Rules may only be permitted with the permission of the State Mining and Technical Supervision Authority of Russia.
To obtain a permit, an enterprise must provide the Gosgortekhnadzor of Russia with the appropriate justification, and, if necessary, also the conclusion of a specialized organization. A copy of the permission to deviate from the Rules must be attached to the boiler passport.
1.2. Responsibility for violations of the Rules
1.2.1. The rules are mandatory for managers and specialists involved in the design, manufacture, installation, adjustment, repair, technical diagnostics, inspection and operation of boilers, autonomous steam superheaters, economizers and pipelines within the boiler (3).
1.2.2. The organization (regardless of depending on departmental affiliation and forms of ownership) who performed the relevant work.
1.2.3. Managers and specialists of organizations engaged in design, construction, manufacturing, adjustment, technical diagnostics, examination and operation who violated the Rules are liable in accordance with the legislation of the Russian Federation.
Canceled due to release.
The rules for the design and safe operation of steam and hot water boilers establish requirements for the design, construction, materials, manufacture, installation, commissioning, repair and operation of steam boilers, autonomous steam superheaters and economizers with an operating pressure of more than 0.07 MPa (0.7 kgf/cm2 ), hot water boilers and autonomous economizers with water temperatures above 115°C.
The rules are mandatory for managers and specialists involved in the design, manufacture, installation, adjustment, repair, technical diagnostics, inspection and operation of boilers, autonomous steam superheaters, economizers and pipelines within the boiler.
In connection with the entry into force of these Rules after their official publication, the Rules for the Design and Safe Operation of Steam and Hot Water Boilers (Order of the Gosgortekhnadzor of Russia dated July 17, 2003 No. 156) are considered invalid.
I. General provisions
1.1. Purpose and scope of the Rules
1.2. Responsibility for violations of the Rules
1.3. Boilers and semi-finished products purchased abroad
1.4. Procedure for investigating accidents and accidents
II. Design
2.1. Project development
2.2. Changing boiler designs
III. Design
3.1. General provisions
3.2. Water level position
3.3. Manholes, hatches, covers and combustion doors
3.4. Safety devices for furnaces and flues
3.5. Cast iron economizers
3.6. Bottoms and tube sheets
3.7. Welded joints, location of welds and holes
3.8. Curvilinear elements
3.9. Rolling connections
3.10. Blowing, emptying and drainage systems
3.11. Burner devices
IV. Materials and semi-finished products
4.1. General provisions
4.2. Semi-finished steel products. General requirements
4.3. Sheet steel
4.4. Steel pipes
4.5. Steel forgings, stampings and rolled products
4.6. Steel castings
4.7. Fasteners
4.8. Cast iron castings
4.9. Non-ferrous metals and alloys
4.10. Requirements for new steel grades
V. Manufacturing, installation and repair
5.1. General provisions
5.2. Cutting and deforming semi-finished products
5.3. Welding
5.4. Heat treatment
5.5. Control
5.6. Visual and measuring control
5.7. Radiographic and ultrasonic testing
5.8. Penetrant and magnetic particle testing
5.9. Control by steeloscopy
5.10. Hardness measurement
5.11. Control by passing a metal ball
5.12. Mechanical testing, metallographic testing and intergranular corrosion testing
5.13. Quality assessment standards
5.14. Hydraulic tests
5.15. Correction of defects in welded joints
5.16. Passport and labeling
VI. Fittings, instruments and feeding devices
6.1. General provisions
6.2. Safety devices
6.3. Water level indicators
6.4. Pressure gauges
6.5. Temperature measuring instruments
6.6. Shut-off and control valves
6.7. Safety devices
6.8. Nutritional devices
VII. Boiler room
7.1. General provisions
7.2. Lighting
7.3. Placement of boilers and auxiliary equipment
7.4. Platforms and stairs
7.5. Fuel supply and ash removal
VIII. Water-chemical regime of boilers
8.1. General requirements
8.2. Feed water quality requirements
8.3. Boiler water quality requirements
IX. Organization of safe operation and repair
9.1. Organization of safe operation
9.2. Service
9.3. Checking instrumentation, automatic protection, fittings and feed pumps
9.4. Emergency stop of the boiler
9.5. Organization of repairs
X. Registration, technical examination and permission to operate
10.1. Registration
10.2. Technical examination
10.3. Commissioning work
10.4. Permission to operate newly installed boilers
XI. Additional requirements for boilers operating with high-temperature organic coolants
11.1. General provisions
11.2. Design
11.3. Armature
11.4. Liquid level indicators
11.5. Pressure gauges
11.6. Temperature measuring instruments
11.7. Safety valves
11.8. Expansion vessels
11.9. Automatic protection
11.10. Pumps
11.11. Installation and operation
XII. Additional requirements for soda recovery boilers
12.1. General provisions
12.2. Design, equipment and control
12.3. Installation and operation
XIII. Additional requirements for gas-tube boilers
13.1. General provisions
13.2. Design
13.3. Automatic protection
XIV. Monitoring compliance with these Rules
Appendix 1. Brief table of relationships between International System (SI) units and other units of physical quantities adopted in these Rules
Appendix 2. Basic terms and definitions
Appendix 3. Legend and units of measurement
Appendix 4. Boiler passport (autonomous superheaters and economizer)
Appendix 4a. Boiler passport
Appendix 5. Materials used for the manufacture of boilers, superheaters, economizers operating under pressure
Appendix 6. Division of steels into types and classes
Appendix 7. Definition of the concepts of similar and control welded joints
Appendix 8. Standards for assessing the quality of welded joints
4-1. REQUIREMENTS OF GOSGOTEKHNADZOR RULES
The operation of steam and hot water boilers must be carried out in strict accordance with the “Rules for the design and safe operation of steam and hot water boilers” of the USSR State Mining and Technical Supervision. The design of the boiler, steam superheater and water economizer must be reliable and safe in operation, and must also provide the possibility of inspection, cleaning using mechanized means, blowing, washing and repair of all elements of the unit.
The design and hydraulic circuit of the boiler, superheater and water economizer must ensure reliable cooling of the walls of the elements under pressure. The placement of non-insulated elements of drums and collectors in the combustion space and in gas ducts is permitted only if these elements are reliably cooled from the inside by liquid. During lighting and normal operation, all boiler elements must be heated evenly and be able to move freely due to thermal expansion. Boilers with a capacity of 10 t/h and above must have benchmarks (displacement indicators) installed to control the movement of elements due to thermal expansion.
The design organization is responsible for the correct design of the boiler, superheater, economizer and its elements, strength calculations and selection of materials; the manufacturer is responsible for the quality of manufacturing; installation and repair are the responsibility of the organization.
tions who performed these works. Changes to the boiler design can only be made in agreement with the manufacturer or a specialized organization that has the right to reconstruct boiler units.
Each boiler unit is equipped with the required number of manholes, hatches, peepholes and combustion doors used during operation to monitor its operation and repair.
In accordance with the “Rules” of Gosgortekhnadzor, steam and hot water boilers are equipped with devices and instruments that ensure safe conditions operation. Such devices include: boiler safety valves, safety devices flue pipes, boiler water level indicators, feed pumps, measuring instruments and safety devices.
Steam boilers with a capacity of more than 100 kg/h must have at least two safety valves: one control and one operating. With two safety valves and a non-switchable superheater, one valve (control) is installed on the outlet manifold of the superheater. When operating steam boilers, the safety valves are adjusted in accordance with the data in Table. 4-1. At the same time, in order to avoid damage to the superheater, and should always be opened first. The last to close is the safety valve installed on the superheater outlet manifold.
At least two safety valves are also installed on water heating boilers. At the same time, safety valves may not be installed on direct-flow water heating boilers with chamber fireboxes equipped with automatic safety systems. Safety valves of water heating boilers are regulated at the moment they begin to open at a pressure not exceeding 1.08 working pressure in the boiler.
Economizers switched off on the water side are equipped with one safety valve at the water inlet and one safety valve at the economizer outlet! The valve is installed at the water inlet to the economizer after the shut-off element, and at the outlet from the economizer -j- to the shutdown element. The safety valve at the water inlet to the economizer should open when the pressure exceeds 25%, and at the outlet from the economizer - by 10% of the operating pressure in the boiler.
The safety valves of the boiler, superheater and water economizer must be checked systematically. The serviceability of safety valves is checked by blowing (“by manually blowing”). The check is carried out each time the boiler, superheater and economizer are started, as well as during their operation. For boilers, steam superheaters and economizers operating with pressure up to 2.35 MPa inclusive, each valve is checked at least once a day, and with pressure from 2.35 to 3.82 MPa inclusive, it is checked one by one, but at least one valve per day. The safety valves are checked in the presence of the shift supervisor and recorded in the logbook.
The main problems with the operation of safety valves are: steam loss, delay in lifting and frequent operation under sharply fluctuating loads. The passage of steam through the valve leads to its premature wear, so after checking or operating the valve, you should make sure that it is tightly seated. The passage of steam can occur due to misalignment, foreign objects getting under the valve, spontaneous movement of a load, etc. Delay in lifting the valve occurs when it sticks, spontaneous movement of the load, when the pressure on the spring increases, when the guide ribs jam in the seat and the rod in where it passes through the lid. To avoid frequent operation of the valve under fluctuating loads, the pressure in the boiler is maintained at 0.10-0.15 MPa less than the working pressure to which the valves are adjusted.
To protect the lining and gas ducts from destruction during explosions, boilers with chamber furnaces (combustion of pulverized, liquid, gaseous fuels), as well as with a shaft furnace for burning peat, sawdust, shavings and other small industrial waste, are equipped with explosion safety valves. In Fig. Figure 4-1 shows the designs of the safety valves used. The valves are installed in the lining of the furnace, the last gas duct of the boiler, the economizer and the ash collector. It is allowed not to install explosion valves in the lining of boilers that have one passage of combustion products, as well as in gas ducts in front of smoke exhausters.
For boilers with a capacity of less than 10 t/h, the number, placement and dimensions of explosion safety valves are established by the design organization. Typically, design organizations select the area of the explosion valves for these boilers at the rate of 250 cm 2 of the area of the explosion valve per 1 m 3 of the volume of the furnace or boiler flues. As an example in Fig. Figure 4-2 shows the placement of explosion safety valves on DKVR type boilers. For boilers with a capacity from 10 to 60 t/h in the upper part of the lining above the firebox
Explosive valves with an area of at least 0.2 m2 are installed. At least two safety valves with a total minimum cross-section of 0.4 m2 are installed on the last gas duct of the boiler, the water economizer gas duct and the ash collector gas duct. When operating explosion safety valves made of asbestos, it is necessary to ensure their integrity. Experience shows that due to pulsations in the firebox, the valve may rupture, which leads to increased suction of cold air. When making explosion valves in the form of hinged doors, it is necessary to check the tight fit of the valve to the frame.
Water indicators and “reduced” level indicators installed at the boiler service area must be systematically checked. The water indicators of boilers operating at pressures up to 2.35 MPa are checked every shift, and boilers with pressures above 2.35 MPa are checked once a day. A comparison of the readings of lowered level indicators and water indicating devices must be carried out at least once per shift with a recording of the performed operation in the logbook.
When operating water-indicating devices, the following malfunctions are observed in their operation: clogged valves, passage of steam through leaks, glass fragility. When passing steam through leaks in the valve of the upper head, the water level in the water-indicating glass will be higher than actual. When passing steam through leaks in the valve of the lower head the water level in the water indicator glass will be too low
wives To eliminate the brittleness of glass, it should be boiled in clean lubricating oil for 20-30 minutes and then cooled slowly.
When operating boiler shop equipment, the serviceability of all installed feed pumps is systematically checked. For boilers with a pressure of up to 2.35 MPa, each of the pumps is briefly put into operation at least once per shift, and for boilers with high pressure - within the time limits specified in the production instructions, but at least once every 2-3 days. During a test run of the pumps, they check the pressure they create, the absence of leaks through leaks, the heating of the bearings, the amplitude of vibration, and the serviceability of the pump drive (electric motor, turbine, steam engine).
To control the operation of the boiler and to regulate the combustion process, a set of measuring instruments is installed. The volume of thermal control of the boiler is selected depending on the productivity of the latter, the type of fuel and the method of its combustion, the design features of the boiler and other factors. However, each boiler unit, in accordance with the “Rules” of Gosgortekhnadzor, must have a certain minimum number of devices, without which its operation is not allowed.
A steam boiler must have instruments for measuring the steam pressure in the boiler drum and after the superheater, the feedwater pressure in front of the body that regulates its supply to the boiler, the water pressure at the inlet and outlet of the economizer that is switched off by water, the temperature of the superheated steam up to the main steam valve of the boiler, steam temperature before and after the desuperheater, feed water temperature before and after the water economizer.
A hot water boiler must have instruments for measuring the water pressure at the inlet and the heated water at the outlet of the boiler, the water pressure on the suction and discharge lines of the circulation pump, the water pressure on the boiler supply line or the heating network make-up, the water temperature at the inlet and outlet of the boiler.
On steam boilers with a capacity of more than 10 t/h and hot water boilers with a power of more than 5815 kW, the installation of a recording pressure gauge is required. On steam boilers with natural circulation with a capacity of more than 20 t/h and direct-flow boilers with a productivity of more than 1 t/h, as well as on hot water boilers with a power of more than 1163 kW, the device for measuring the temperature of superheated steam and heated water must be recording. The pressure and temperature of hot water in hot water boilers are measured between the boiler and the shut-off valve.
For boiler units that burn liquid fuel, its temperature and pressure are measured in front of the nozzles. When ra-
bot on gaseous fuel The gas and air pressure must be measured in front of each burner after the regulators, as well as the vacuum in the upper part of the combustion chamber.
Operating personnel are obliged to systematically monitor the accuracy of the readings of control and measuring instruments. L Boiler operators check pressure gauges at least once per shift using three-way valves or valves that replace them. The engineering and technical personnel of the boiler shop check the working pressure gauges at least once every six months by comparing their readings with the control pressure gauge. The inspection is recorded by an entry in the control check log.
It is not allowed to use pressure gauges without a seal, brand or with an expired inspection date, with broken glass or other damage that affects the accuracy of the readings, with an arrow that does not return to the zero position when the pressure gauge is turned off (deviation from the zero position is allowed by an amount not greater than half the error pressure gauge).
In order to increase reliability, boiler units are equipped with safety devices that stop the operation of the boiler in the event of emergency situations. Boilers with a steam capacity of 0.7 t/h and above must have automatically operating sound alarms for the lower and upper limit water levels in the boiler drum. If these boilers have chamber fireboxes, then an automatic device is additionally installed that stops the supply of fuel to the burners (pulverized, gas, fuel oil) if the water level in the drum decreases beyond the permissible limit established by the manufacturer.
Direct-flow water heating boilers with chamber combustion chambers are equipped with automatic devices, stopping the supply of fuel to the burners, and boilers with layered fireboxes - devices that turn off the fuel supply mechanisms (fuel feeders, throwers, chain grates) and draft machines, in the following cases:
a) increasing the water pressure in the boiler outlet manifold
up to 1.05 pressure obtained when calculating the strength of the heating network pipeline and boiler;
b) reducing the water pressure in the boiler outlet manifold
to a value corresponding to saturation pressure at maximum operating temperature water leaving the boiler;
c) increasing the temperature of the water leaving the boiler to
values are 20 °C lower than the saturation temperature, which corresponds to the operating water pressure in the boiler outlet manifold;
d) such a reduction in water flow through the boiler, when
torus subheating of water to boiling at the outlet of the boiler at maximum
at maximum load and operating pressure in the outlet manifold reaches 20°C.
Safety valves on a direct-flow water heating boiler with a chamber fire may not be installed if the specified protection is available. Exceeding the temperature of the heated water to the specified value is dangerous, as it can cause water hammer due to partial steam formation. To avoid local boiling, the average water speed in individual heated pipes must be at least 1 m/s. The temperature of the heated water may reach the limit value due to insufficient operating pressure, increased boiler boost or a noticeable decrease in water flow. During operation, water consumption should not be allowed to decrease below the minimum. Minimum permissible water flow (in kg/s)
where Q max - maximum power boiler, kW; ts- saturation temperature at operating pressure at the boiler outlet, °C; t in- water temperature at the boiler inlet, C.
When burning gaseous fuel, in addition to the specified safety devices, steam and hot water boilers must be equipped with automatic equipment that ensures that the gas supply is stopped in the event of:
a) gas pressure deviations within unacceptable limits;
b) the flame goes out on at least one of the main burners;
c) traction disturbances (increase or decrease in vacuum
in the upper part of the firebox within unacceptable limits);
d) stopping the air supply or reducing its pressure in front of the burners beyond the established limit (for boilers,
equipped with burners forced submission air).
In order to increase safety when burning gaseous fuel, flue gates must have holes with a diameter of at least 50 mm for continuous ventilation of the firebox and gas ducts. The removal of combustion products from boilers that burn gas and boilers that use other fuels into a common waste stream is permitted only for existing boiler houses converted to gas. In this case, the start-up of units using gaseous fuel should be carried out only when the remaining units operating on other fuels are stopped. If stopping these units when starting one of the gas boilers is impossible, then special safety measures are developed, agreed upon with the local Gosgortekhnadzor authority.
Safety devices of the boiler unit are systematically checked for operation within the time limits specified by the factory -
by the manufacturer, and mandatory every time the boiler is stopped. The boiler shop usually draws up a schedule of preventive maintenance and testing of all installed instrumentation and safety devices, approved by the chief engineer of the enterprise.
STEAM BOILERS
When operating vertical cylindrical boilers, special attention should be paid to systematic monitoring of the condition of the heating surface. The most common damage to vertical cylindrical boilers is bulging and cracking of the firebox sheets. In this regard, in boilers of the MZK type, the combustion chamber is covered with a protective refractory lining, the integrity of which must be systematically monitored. When setting up the boiler and setting up the automation, you should especially carefully select air mode fireboxes in order to avoid the occurrence of chemical underburning during operation, since the presence of the latter leads to the deposition of soot on heating surfaces, the cleaning of which is extremely difficult. Periodically, a complete analysis of combustion products should be carried out and changes in the temperature of the flue gases should be monitored. An increase in the flue gas temperature after starting the boiler indicates contamination of the heating surface.
Vertical water tube boilers currently produced by industry have horizontal or vertical orientation of heating surfaces. Of the old types of horizontally oriented boilers, DKVR boilers from the Biysk Boiler Plant are in use in large numbers. DKVR boilers were designed for burning solid fuels, but were later adapted for burning liquid and gaseous fuels.
Operating experience and inspection of DKVR boilers carried out by TsKTI showed that the main disadvantages in their operation are: significant air suction into the flue of convective beams (in heavy lining Aa K = 0.4-f-0.9; and in lightweight lining with metal lining Yes k = 0.2-t-0.5) and especially in the flue of cast iron water economizers; insufficient degree of factory readiness; long installation times; lower operational efficiencies compared to calculated ones. Fuel burnout due to air suction is estimated at 2 to 7%. Therefore, when operating DKVR boilers, it is necessary to systematically eliminate leaks that appear in the insulation area of the upper drum.
When operating on gas and fuel oil in DKVR boilers, the part of the upper drum located in the combustion chamber must be protected from radiation. Operating experience has shown that drum protection using shotcrete is fragile and is destroyed within one to two months. Protect the drum more reliably
shaped refractory bricks. The design of fastening refractory bricks is shown in Fig. 4-3.
Due to the indicated shortcomings boilers of the DKVR type, TsKTI, together with BiKZ, developed gas-oil boilers of the DE type for burning gas and fuel oil, and boiler units of the KE type for burning solid fuels based on DKVR boilers. DE and KE boilers are supplied in full factory readiness.
DE type boilers have a number of design features: upper and lower drums of the same length; from convective
the combustion chamber is separated by a gas-tight partition; the pipes of the partition and the right side screen, which also covers the under and ceiling of the firebox, are inserted directly into the upper and lower drums; the ends of the rear and front screen pipes are welded to the upper and lower branches of the C-shaped collectors; all combustion chamber screens and the partition separating the firebox from the convective flue are made of pipes, between which spacers are welded to ensure the required density; The boiler lining is made of slabs, which have a casing on the outside about 1 mm thick.
When operating horizontally oriented boilers with lower distributing and upper collecting manifolds, careful control should be exercised over the condition of the heating surface pipes, since the circulation of the steam-water emulsion in them is less reliable. To increase the reliability of circulation in these boilers, the installation of recirculation pipes is provided (for example, in the DKVR-20 boiler). Recirculation pipes are lowering unheated pipes that connect the upper manifold of the circuit with the lower one.
 |
During operation of the boiler unit, failure of individual heating surface pipes is possible. In this case, a plug is placed temporarily until the pipes are replaced. For boilers operating at pressures up to 1.27 MPa, it is recommended to use the plug shown in Fig. 4-4. The plug consists of two parts: a pipe cut from a pipe, and a bottom. The pipe is rolled into the hole, and then from the side inner surface The bottom of the drum is welded or installed on the thread. When welding the bottom, heating of the rolling joint is not allowed in order to avoid violating its density.
When starting up and operating the DKVR and KE boilers, it is necessary to monitor the thermal expansion of the front ends of the side screen chambers and the rear bottom of the lower drum, on which benchmarks are usually installed.
The operational reliability of horizontally oriented boilers largely depends on the firing mode. To reduce the heating time and reduce the difference in water temperature in these boilers, you should use a device for heating water in the lower drum. To do this, steam is supplied from operating boilers through the supply steam line to the lower drum before starting the furnace. It is recommended to heat the water in the boiler to a temperature of 90-100 °C. Steam heating of the lower drum is stopped when the pressure in the boiler reaches 0.75 times the pressure of the heating steam, and after that the furnace is started, melting it under fire heating. The pressure rise on horizontally oriented boilers designed for a pressure of 1.27 MPa is carried out so that 1.5 hours after kindling the pressure in the drum is 0.1 MPa, and after another 2.5 hours it is 0.4-0.5 MPa and after 3 hours - 1.27 MPa.
Currently, the Belgorod Power Engineering Plant (BZEM) produces many modifications of vertically oriented boiler units with a capacity of up to 75 t/h and a pressure of 1.4-4.0 MPa. All vertically oriented boilers have a U-shaped arrangement of heating surfaces and continuous shielding of the combustion chamber. The boiler units are quite reliable in operation and have high maintainability. The main disadvantage of boilers in operation is the increased suction of cold air into the flues from the firebox to the last heating surface (Aa = 0.25 ^ 0.35).
When burning solid fuel with a high ash content, it is necessary to monitor the wear of the heating surface
boiler Ash wear depends on the rate of combustion products and the concentration of ash and entrainment. Particularly dangerous are the increased local velocities and concentrations that are observed in the gas corridors between the walls of the flue and pipes, as well as in places where individual pipes and coils are aligned (breakage of fastenings and the appearance of various gaps between pipes and coils for the passage of combustion products). Pipes located near leaks in gas partitions and in the zone of rotation of combustion products are also subject to greater wear.
When operating any boiler units, engineering and technical personnel must pay special attention timely detection of damage to heating surface pipes. When fistulas form in the pipes of the boiler, and especially the superheater, steam and water coming out of them at high speed, mixing with ash, intensively destroy neighboring pipes. The appearance of fistulas is also dangerous when burning fuel oil.
Leaks in the heating surface pipes of the boiler, superheater and water economizer can be identified by noise in the gas ducts, a decrease in the water level in the boiler drum, discrepancies in the readings of the steam meter and water meter, and the appearance of water in slag and ash bunkers. During the shift, it is necessary to walk around the boiler at least twice, looking at the condition of the heating surface through peepers, listening to the furnace, superheater flue, boiler and water economizer gas ducts.
Failure of the heating surface pipes of steam boilers is also observed due to disruption of water circulation. Therefore, in operation, to increase the reliability of circulation, it is necessary to ensure that the correct combustion mode is maintained, to ensure uniform supply of water to the boiler, to avoid sudden fluctuations in steam pressure and water level in the boiler drum, to prevent slagging of the heating surface, to monitor the cleanliness of the inner surface of the pipes, to control the density of the purge fluid. fittings.
Under correct mode combustion means the absence of thermal distortions in the operation of the furnace and the first gas ducts of the boiler, as well as the impact of the torch on the screens and lining, the end of the combustion process within the combustion chamber, maintaining an optimal excess of air in the furnace, the absence of slagging, a gradual change in boost if necessary, maintaining optimal fineness dust and good atomization of liquid fuel, uniform distribution of fuel on the grate during layer combustion.
The pressure in the boiler should be increased gradually, especially at low boiler load, since with intensive boosting of the furnace, the heat absorption of the screen pipes increases noticeably, and the steam content increases much more slowly, because part of the heat is spent on heating the water to a higher temperature.
saturation rate corresponding to the increased pressure. The pressure should be increased so that at reduced loads it grows at a rate of approximately 400 Pa/s, and at nominal loads at a rate of 800 Pa/s. In the event of a sudden load drop, the furnace boost should be immediately reduced to avoid overheating of the screen pipes due to deterioration of circulation.
When operating the valves installed on the boiler, it is necessary to monitor their density, the absence of floating through the flange connections or gland seal, and the ease of movement of the spindle when opening and closing the valves. Valves and valves, which are used in operation to regulate the flow of water or steam, wear out especially quickly. Before each start-up of the boiler unit, all installed fittings must be checked for ease of movement by opening and closing them. When the boiler unit is operating, the density of the fittings is checked by feeling the pipeline, which, when closed position the fittings must be cold.
During an internal inspection of the boiler, engineering and technical personnel should pay attention to the condition of the following elements. In drums, the internal surfaces, welded and riveted seams, and the ends of rolled or welded pipes and fittings are inspected. Damage in the rivet seams of vertical water-tube boilers occurs mainly in the lower drums, at the junction of the longitudinal and transverse rivet seams. Intercrystalline cracks can appear in the tube sheets of drums, as well as in places where feed water and phosphates are introduced. The internal surfaces of the boiler may show corrosive wear, mainly in areas where feed water enters, poor water circulation and where sludge deposits occur.
When inspecting pipes, corner screen pipes, horizontal and slightly inclined sections of boiler pipes are checked. The most common defects of screen and boiler pipes are annular and longitudinal cracks, bulges, fistulas, local thinning of pipe walls and pipe deformation due to scale deposits or circulation problems.
For drums heated by combustion products, the heating areas in which bulges may form are inspected. The condition of the gunite, which protects the drum from overheating, is checked. Cracks may form in the welds of drums and manifolds.
The outer surface of the pipes is inspected from the firebox and flues. Ruptures, bulges, deflections, and tearing of pipes out of tube sheets most often occur in the first rows of pipes facing the furnace. In addition, pipe wear due to ash is checked. Pipe wear is detected using special templates.
It is very important for industrial and hot water boiler units to take measures to prevent corrosion of internal heating surfaces during short or long-term shutdowns. The following cases are distinguished:
a) preservation for a period of less than three days (when stopping the boiler without opening the drum) using steam from a continuous blowing separator or from other boilers;
b) preservation for a period of more than three days (when stopping the boiler without opening the drum) by connecting the boiler to a pipeline with deoxygenated condensate or feed water with a pressure of 0.3-0.5 MPa;
c) preservation for any period (when stopping the boiler and opening the drum) with filling the superheater with condensate containing ammonia (ammonia concentration 500 mg/kg).
| PB 10-574-03 Rules for the design and safe operation of steam and hot water boilers | establish requirements for the design, design, materials, manufacturing, installation, commissioning, repair and operation of steam boilers, autonomous steam superheaters and economizers with an operating pressure of more than 0.07 MPa (0.7 kgf/cm2), hot water boilers and autonomous economizers with water temperature above 115 °C. |
| PB 10-575-03 Rules for the design and safe operation of electric boilers and electric boiler houses | establish requirements for the design, manufacture, installation, repair and operation of electric boilers and apply to steam boilers with an operating pressure of more than 0.07 MPa (0.7 kgf/cm2) and hot water boilers with a water temperature above 115°C |
| GOST 20995-75 Stationary steam boilers with pressure up to 3.9 MPa. Indicators of feed water and steam quality. | sets the values of the quality indicators of feed water and steam of stationary steam boilers in accordance with GOST 3619 with an absolute pressure of up to 3.9 MPa (40 kgf/cm2), including for boilers with a built-on boiler. The standard does not apply to steam boilers with an absolute pressure of 0.9 MPa (9 kgf/cm2) with a steam output of up to 0.7 t/h, operating on solid fuel, as well as to electrode boilers. |
| RTM 108.030.114-77 Low and medium pressure steam boilers. Organization of water chemistry regime | applies to stationary steam boilers with natural circulation in accordance with GOST 3619-76, pressure up to 4 MPa (40 kgf/cm2) and steam output from 0.7 t/h |
| RTM 108.030.130-79 Stationary high-pressure steam boilers with natural circulation. Feed water and steam quality standards. | applies to quality standards for feed water and steam of high-pressure stationary steam boilers with natural circulation and stepwise evaporation at pressures of 100 and 140 kgf/cm2 |
| RD 24.031.120-91 Guidelines. Standards for the quality of network and make-up water for hot water boilers, organization of water chemistry and chemical control. | These guidelines (MU) apply to stationary direct-flow water heating boilers with a heating capacity from 2.33 MW (2 Gcal/h) to 209 MW (180 Gcal/h) with a network water temperature at the boiler outlet of no more than 200 C |
| RD 24.032.01-91 Guidelines. Quality standards for feed water and steam, organization of water chemistry and chemical control of stationary steam waste heat boilers and energy technology boilers. | establish standards for the quality of feed water and steam, requirements and recommendations for the organization of water chemistry and chemical control for steam stationary waste heat boilers and energy technology boilers with a working steam pressure of up to 4 MPa (40 kgf/cm2), for operating boilers - up to 5 MPa (50 kgf/cm2), as well as for boilers with a working steam pressure of 11 MPa (110 kgf/cm2). |
| RD 34.37.506-88 Guidelines for water treatment and water chemistry of water heating equipment and heating networks | apply to water heating equipment with a capacity of over 58 MW and heating networks, included in the RAO UES of Russia system, and establish requirements for the selection of water treatment schemes, water chemistry regime, ensuring reliable operation of the main and auxiliary equipment of heat supply systems at necessary composition water and heat treatment equipment. |
Back to Water treatment for the boiler room
Excerpt from PB 10-574-03 RULES FOR THE CONSTRUCTION AND SAFE OPERATION OF STEAM AND WATER HOT BOILERS
VIII. WATER CHEMICAL REGIME OF BOILERS
8.1. General requirements
8.1.1. The water chemistry regime must ensure operation of the boiler and feed tract without damage to their elements due to scale and sludge deposits, an increase in the relative alkalinity of the boiler water to dangerous limits, or as a result of metal corrosion.
All steam boilers with natural and multiple forced circulation with a steam output of 0.7 t/h or more, all once-through steam boilers regardless of steam output, as well as all hot water boilers must be equipped with installations for pre-boiler water treatment. It is also permissible to use other effective methods of water treatment that guarantee compliance with the requirements of this article.
8.1.2. The choice of water treatment method for feeding boilers should be carried out by a specialized organization.
8.1.3. For boilers with a steam capacity of less than 0.7 t/h, the period between cleanings should be such that the thickness of deposits in the most heat-stressed areas of the heating surface of the boiler does not exceed 0.5 mm by the time it is stopped for cleaning.
8.1.4. Feeding boilers equipped with devices for pre-boiler water treatment with raw water is not permitted.
In cases where the project provides for feeding the boiler with raw water in emergency situations, two shut-off devices and a control valve between them must be installed on the raw water lines connected to the lines of softened additional water or condensate, as well as to feed tanks. During normal operation, the shut-off elements must be in the closed position and sealed, and the control valve must be open.
Each case of feeding boilers with raw water must be recorded in a water treatment log (water chemistry regime) indicating the duration of the feeding and the quality of the feed water during this period.
8.1.5. For steam and hot water boilers, commissioning organizations must develop instructions and regime maps for maintaining the water chemical regime, taking into account these Rules, the instructions of the manufacturing organizations, methodological instructions on the development of instructions and regime maps for the operation of pre-boiler water treatment plants and for maintaining the water chemistry regime of steam and hot water boilers, approved by the State Technical Supervision Authority of Russia. Instructions for the operation of pre-boiler water treatment plants should be developed by the organizations that manufacture the plants.
8.1.6. Instructions and regime cards must be approved by the head of the organization that owns the boiler and be located at the personnel’s workplaces.
8.2. Feed water quality requirements
8.2.1. The quality indicators of feed water for boilers with natural and multiple forced circulation with a steam capacity of 0.7 t/h or more should not exceed the values specified:
a) for steam gas-tube boilers - in table. 3;
Table 3. Feedwater quality standards for gas-tube steam boilers
|
Indicator |
For boilers operating |
|
|
liquid fuel |
on other types of fuel |
|
|
Total hardness, µg×eq/kg |
||
|
50 8 |
||
|
8 For boilers without economizers and boilers with cast iron economizers, the dissolved oxygen content is allowed from 100 μg/kg. |
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b) for water-tube boilers with natural circulation (including boiler-boilers) and operating steam pressure up to 4 MPa (40 kgf/cm2) - in table. 4;
Table 4. Feed water quality standards for water tube boilers with natural circulation and operating steam pressure up to 4 MPa (40 kgf/cm2)
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Indicator |
||||
|
0,9 (9) |
1,4 (14) |
2,4 (24) |
4 (40) |
|
|
Font transparency, cm, no less |
||||
|
Total hardness, µg×eq/kg |
30 9 |
15 14 |
10 14 |
5 14 |
|
Not standardized |
300 14 Not standardized |
100 14 |
50 14 |
|
|
Not standardized |
10 14 Not standardized |
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|
50 14 |
30 14 |
20 14 |
20 14 |
|
|
pH value at 25 °C 11 |
8,5 - 10,5 |
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|
9 The numerator shows values for boilers operating on liquid fuel, the denominator - on other types of fuel. 10 For boilers without economizers and for boilers with cast iron economizers, the content of dissolved oxygen is allowed up to 100 μg/kg when burning any type of fuel. 11 In some cases, justified by a specialized organization, a decrease in pH value to 7.0 may be allowed. |
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c) for water tube boilers with natural circulation and a working steam pressure of 10 MPa (100 kgf/cm2) - in table. 5.
Table 5. Feed water quality standards for water tube boilers with natural circulation and operating steam pressure of 10 MPa (100 kgf/cm2)
|
Indicator |
For boilers operating |
|
|
liquid fuel |
on other types of fuel |
|
|
Total hardness, µg×eq/kg |
||
|
pH value at 25 °C 12 |
9.1 ± 0.1 |
9.1 ± 0.1 |
|
Note . For vertical-type gas-tube waste heat boilers with an operating steam pressure of over 0.9 MPa (9 kgf/cm2), as well as for soda recovery boilers, feed water quality indicators are normalized according to the values of the last column of the table. . In addition, for soda recovery boilers, the salt content of feedwater is standardized, which should not exceed 50 mg/kg. 12 When replenishing the loss of steam and condensate with chemically purified water, it is allowed to increase the pH value to 10.5. |
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d) for energy technology boilers and waste heat boilers with operating steam pressure up to 5 MPa (50 kgf/cm2) - in table. 6;
e) for energy technology boilers and waste heat boilers with a working steam pressure of 11 MPa (110 kgf/cm2) - in table. 7;
Table 6. Feed water quality standards for energy technology boilers and waste heat boilers with operating steam pressure up to 5 MPa (50 kgf/cm2)
|
Indicator |
Working pressure, MPa (kgf/cm2) |
||||
|
0,9 (9) |
1,4 (14) |
4 (40) and 5 (50) |
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|
Heating gas temperature (calculated), °C |
|||||
|
Up to 1200 inclusive |
Up to 1200 inclusive |
Over 1200 |
Up to 1200 inclusive |
Over 1200 |
|
|
Font transparency, cm, no less |
30 13 |
40 18 |
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|
Total hardness, µg×eq/kg |
40 18 |
20 14 |
|||
|
Not standardized |
50 15 |
||||
|
a) for boilers with a cast iron economizer or without an economizer, µg/kg |
|||||
|
b) for boilers with a steel economizer, µg/kg |
|||||
|
pH value at 25 °C |
Not less than 8.5 16 |
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|
13 The numerator indicates the value for water-tube boilers, the denominator - for gas-tube boilers. 14 For water-tube boilers with a working steam pressure of 1.8 MPa (18 kgf/cm2), the hardness should not be more than 15 mcg×eq/kg. 15 It is allowed to increase the content of iron compounds to 100 μg/kg, subject to the use of reagent water treatment methods that reduce the intensity of scale formation by transferring iron compounds into solution, while the standards agreed with Gosgortekhnadzor of Russia on the permissible amount of deposits on the inner surface of steam-generating pipes must be observed. A conclusion on the possibility of this increase in the content of iron compounds in feed water is given by a specialized research organization. 16 The upper pH value is set to no more than 9.5, depending on the materials used in the equipment of the steam-condensate path. |
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Table 7. Feed water quality standards for energy technology boilers, waste heat boilers with a working steam pressure of 11 MPa (110 kgf/cm2)
|
Indicator |
Meaning |
|
Total hardness, µg×eq/kg |
|
|
pH value at 25 °C |
9.1 ± 0.1 17 |
|
Conditional salt content (in terms of NaCl), µg/kg |
|
|
Specific electrical conductivity at 25 °C, µS/cm 18 |
|
|
17 The upper pH value is set to no more than 9.5, depending on the materials used in the equipment of the steam-condensate path. 18 Conditional salt content should be determined by a conductometric salinity meter with preliminary degassing and concentration of the sample, and specific electrical conductivity by a conductivity meter with preliminary hydrogen cationization of the sample; one of these indicators is controlled. |
|
f) for high-pressure boilers of combined cycle gas plants - in table. 8.
Table 8. Feed water quality standards for high-pressure boilers of combined cycle gas plants
|
Indicator |
Working pressure, MPa (kgf/cm2) |
||
|
Total hardness, µg×eq/kg |
|||
|
50 19 |
30 24 |
20 24 |
|
|
pH value at 25 °C |
9.1 ± 0.2 |
9.1 ± 0.1 |
9.1 ± 0.1 |
|
Conditional salt content (in terms of NaCl), µg/kg 20 |
Not standardized |
||
|
Specific electrical conductivity at 25 °C, μΩ/cm 25 |
Not standardized |
||
|
19 It is allowed to exceed the iron content standards by 50% when the steam generator operates on natural gas. 20 Conditional salt content should be determined by a conductometric salinity meter with preliminary degassing and concentration of the sample, and specific electrical conductivity by a conductivity meter with preliminary hydrogen cationization of the sample; one of these indicators is controlled. |
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8.2.2. The quality indicators of feedwater for water-tube boilers with natural circulation and a working steam pressure of 14 MPa (140 kgf/cm2) and for all energy once-through boilers must meet the requirements of the ND in force in the electric power industry and agreed with the State Technical Supervision Authority of Russia.
8.2.3. The quality of make-up and network water for hot water boilers must meet the requirements specified in table. 9.
Table 9. Quality standards for make-up and network water for hot water boilers
|
Indicator |
Heating system |
|||||||
|
Open |
Closed |
|||||||
|
Network water temperature, °C |
||||||||
|
Font transparency, cm, no less |
||||||||
|
Carbonate hardness, µg×eq/kg: |
800 21 |
750 26 |
375 26 |
800 26 |
750 26 |
375 26 |
||
|
at pH no more than 8.5 |
700 30 |
|||||||
|
300 26 |
250 26 |
600 26 |
500 26 |
375 26 |
||||
|
pH value at 25 °C |
From 7.0 to 8.5 |
From 7.0 to 11.0 22 |
||||||
|
Note . These standards do not apply to hot water boilers installed at thermal power plants, thermal power plants and heating boiler houses, for which the water quality must meet the requirements of the rules for the technical operation of power plants and networks approved in the prescribed manner. 21 The numerator shows the values for boilers using solid fuels, the denominator for boilers using liquid and gaseous fuels. 22 For heating networks in which hot water boilers operate in parallel with boilers with brass tubes, the upper pH value of the network water should not exceed 9.5. |
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8.3. Boiler water quality requirements
Boiler water quality standards, the required regime for its corrective treatment, continuous and periodic blowdown regimes are adopted on the basis of the instructions of the boiler manufacturer, standard instructions for maintaining a water chemistry regime and other departmental regulatory documents or based on the results of thermochemical tests.
At the same time, for steam boilers with a pressure of up to 4 MPa (40 kgf/cm2) inclusive, having riveted joints, the relative alkalinity of the boiler water should not exceed 20%; for boilers with welded drums and pipes fastened using the rolling method (or rolling with seal welding), the relative alkalinity of boiler water is allowed up to 50%; for boilers with welded drums and welded pipes, the relative alkalinity of boiler water is not standardized.
For steam boilers with pressures above 4 MPa (40 kgf/cm2) up to 10 MPa (100 kgf/cm2) inclusive, the relative alkalinity of boiler water should not exceed 50%, for boilers with pressures above 10 MPa (100 kgf/cm2) up to 14 MPa (140 kgf/cm2) inclusive should not exceed 30%.
