The PSK maintains the gas pressure at the outlet of the hydraulic fracturing unit by removing a certain amount of gas into the atmosphere, while increasing the controlled pressure by 15% of Pout.
1-membrane; 2-valve seat; 3-spring.
The gas outlet pressure is applied to the valve diaphragm; the diaphragm position is adjusted by a spring. As the gas outlet pressure increases, the membrane bends downwards, the valve seat is lowered and the gas is discharged into the atmosphere.
21. Gas pressure regulators. (Functions of the pressure regulator, classification - according to the principle of operation, according to the design of the throttle body, according to the design of the pulse elements, according to the pressure value - schematic diagram of automatic gas control, schematic diagram of the RDUK). Selecting a pressure regulator.
Direct acting gas pressure regulator without amplifier.
Schematic diagram of automatic gas control:
1-supply gas pipeline with gas pressure P 1; 2-control valve; 3-valve seat; 4-membrane; 5-outlet gas pipeline with gas pressure P 2; 6-pulse line.
Purpose of the gas pressure regulator:
Reducing gas pressure from inlet to outlet design;
Maintaining gas outlet pressure within specified limits;
Restoring gas outlet pressure after an external disturbance.
Regulators are divided according to their operating principle into: - direct action; - not direct action. According to the design of the throttle body (with single-throttle and double-throttle valves). According to the design, pulse elements are divided into membrane and piston. According to the amount of adjustable pressure.
The gas flow rate in the gas supply system decreases, therefore the output pressure P2 increases, a pulse of increased output pressure enters the membrane, the membrane bends down, the valve is lowered and the flow section of the pressure regulator is covered. The pressure in the outlet gas pipeline decreases.
The gas flow in the gas supply system increases, therefore the output pressure P2 decreases, a pulse of reduced output pressure arrives at the membrane, the membrane bends upward, the valve rises and the flow section of the pressure regulator opens slightly. The pressure in the outlet gas pipeline increases.
Direct acting pressure regulator.
A direct-acting pressure regulator is a device in which the energy of the controlled medium is used to move the regulating body. Direct-acting pressure regulators are divided into: with amplifier; without amplifier. The pilot serves as an amplifier.
RDUK - Kazantsev design.
1- pressure regulator body; 2-pressure regulator valve; 3-diaphragm pressure regulator; 4-pilot body; 5-valve “pilot”; 6-pilot spring; 7-diaphragm "pilot".
The gas flow rate in the gas supply system increases, therefore the output pressure P2 decreases, a pulse of reduced output pressure arrives at the regulator membrane and the “pilot” membrane, the “pilot” membrane bends upward, the valve rises up and the flow area of the “pilot” increases. Pressure P 1 enters the “pilot” and decreases to the command pressure P k. P k increases, a pulse of increased pressure P k is supplied under the regulator membrane. The regulator diaphragm bends upward and the regulator valve moves upward. The flow area of the regulator increases, the outlet pressure increases.
Selecting a pressure regulator.
The choice is made based on gas pressure, ambient temperature, and regulator capacity V p = 1.2V, m 3 /h. Where V r is the design capacity of the regulator, m 3 / h; V - gas consumption for the network, m 3 / h.
Regulator capacity Q=1595 f k φ P 1 √1/ ρ g, m 3 /h, where Q is the regulator capacity, m 3 /h. f - cross-sectional area of the nominal diameter of the inlet flange, cm 2 according to the regulator passport. k is the flow coefficient related to the area of the inlet flange according to the passport. φ is a coefficient that depends on the ratio of P 2 to P 1 and is taken according to the schedule. Р 2 and Р 1 – absolute gas pressure at the inlet and outlet of the hydraulic fracturing unit, MPa. ρ g – gas density, kg/m3. Vр = Q. Δ+10% - permissible discrepancy.
Safety relief valves PSK 25 are devices membrane type and are designed to discharge gas into the atmosphere when the pressure (in the network or tank) increases above the permissible limit and are installed on gas pipelines and gas control stations of low, medium and high pressure.
Connection to the pipeline is coupling (GOST 6357) or flange.
PSK valves with nominal bore DN 25
are produced in several types:
- relief valves low pressure triggering – PSK-25-P-N;
- high pressure relief valves - PSK-25-P-V.
Relief valves PSK 25 - technical characteristics:
| Name | Conditional passage | Regulation limit, kPa | Bandwidth
|
| PSK-25-P-N | 25 mm | 2,0 -0,1 - 75,0 +7,5 | not less than 120 m 3 / h |
| PSK-25-P-V | 25 mm | 60,0 -6,0 - 750,0 +75,0 | not less than 1000 m 3 / h |
Relief valves PSK 25 - technical parameters:
| Parameter | PSK-25 | PSK-25F |
| Nominal diameter, DN, mm | 25 (1"") | 25 (1"") |
| Valve setting range | from 2 to 750 kPa | from 2 to 750 kPa |
| Housing material | aluminum AK 7h | aluminum AK 7h |
| Working environment | natural gas GOST 5542 |
natural gas GOST 5542 |
| Ambient temperature | from -40 o C to +45 o C | from -40 o C to +45 o C |
| Overall dimensions, no more: - D, mm - H, mm - A, mm - V, mm |
160 210 80 30 |
200 250 120 70 |
| Product weight, no more | 2.34 kg | 4.85 kg |
RELIEF VALVES PSK-50
Relief valves safety PSK 50
are membrane-type devices and are designed to discharge gas into the atmosphere when the pressure (in the network or tank) increases above the permissible limit and are installed on gas pipelines and gas control stations of low, medium and high pressure. Connection to the pipeline is coupling (GOST 6357) or flange.
PSK valves with nominal bore DN 50 are produced in several types:
- low pressure relief valves - PSK-50P-N/20;
- relief valves with medium response pressure – PSK-50-P-S/50;
- relief valves with medium response pressure – PSK-50-P-S/125;
- high pressure relief valves – PSK-50-P-V/1000.
Relief valves PSK 50 - technical characteristics:
| Name | Conditional passage | Regulation limit, kPa | Bandwidth |
| PSK-50P-N/20 | 50 mm | 2,0 -0,1 - 20,0 +2,0 | not less than 200 m 3 / h |
| PSK-50P-S/50 | 50 mm | 20,0 -2,0 - 50,0 +5,0 | not less than 440 m 3 / h |
| PSK-50P-S/12 5 | 50 mm | 50,0 -5,0 - 125,0 +12,5 | not less than 1100 m 3 / h |
| PSK-50P-V/1000 | 50 mm | 125,0 -12,5 - 1000,0 +100 | not less than 5600 m 3 / h |
Relief valves PSK 50 - technical parameters:
| Parameter | PSK-50 (coupled) | PSK-50F (flange) |
| Nominal diameter, DN, mm | 50 (2"") | 50 (2"") |
| Valve setting range | from 2 to 1000 kPa | from 2 to 1000 kPa |
| Housing material | aluminum AK 7h | aluminum AK 7h |
| Working environment | natural gas GOST 5542 |
natural gas GOST 5542 |
| Ambient temperature | from -40 o C to +45 o C | from -40 o C to +45 o C |
| Overall dimensions, no more: - D, mm - N, mm - Ah, mm - V, mm |
220 240 88 43 |
260 300 149 104 |
| Product weight, no more | 4.25 kg | 10.04 kg |
VALVE DEVICE
The appearance of PSK type valves is shown in the figure.The valve body is made in the form of a truncated cone with a flange, a seat and two holes with cylindrical pipe threads 1 inch - version PSK-25P, 2 inches - version PSK-50P or with metric thread M36x1.5 - version PSK-25PF and M56x2 - version PSK-50PF. The seat is closed by valve pos. 3 with rubber seal. The valve is assembled with a membrane pos. 6, which is rigidly fixed between the valve and the plate pos. 7. In turn, the membrane is fixed between the body, pos. 1 and cover pos. 2.
Spring pos. 4 is sandwiched between the membrane plate and the stop pos. 8. By rotating the adjusting screw pos. 5 the stop pos. moves. 8, thus changing the force of the spring, which determines the setting of the valve to pressure within specified limits.
To check the functionality, the valve is equipped with a forced opening mechanism, which is activated by the rod pos. 9.
VALVE OPERATING PRINCIPLE
Gas from the network enters the valve cavity through the inlet of the housing.In steady state, the controlled gas pressure within the set limits is balanced by the adjusted spring, and the valve is hermetically closed.
When the gas pressure in the network (also in the valve cavity) exceeds the setting limit, the membrane, overcoming the forces of the spring, drops along with the valve, opening the gas outlet to the atmosphere through the discharge pipe.
The gas will be released until the pressure in the network drops below the set value, after which the valve will close under the action of the spring.
To check the functionality of the valve, pull the rod of the forced opening mechanism. The valve opens. Repeat the operation 3 – 4 times.
PRICE, PRODUCTION TIME, DELIVERY CONDITIONS
The price for valves PSK-25 and PSK-50 is provided upon official request to our company. The production time for relief valves does not exceed 20 days. Delivery is carried out to all regions of the Russian Federation, as well as to the territory of the CIS countries by any means of transport.The warranty period is 12 months from the date of commissioning of the product, but not more than 18 months from the date of manufacture.
The designated service life of the Valve is 30 years.
To relieve gas downstream of the regulator in the event of a short-term increase in gas pressure above the set value, safety relief valves (PSVs) must be used.
PSK is a valve that is closed in operational condition; it opens for a short period of time, and after reaching the nominal pressure at the controlled point, it automatically closes.
PSC can be spring or membrane. Spring-loaded valves must be equipped with a device for their forced opening and control purging in order to prevent sticking, freezing and sticking of the spool to the seat, as well as to remove solid particles trapped between the sealing surfaces.
PSKs are divided into full-lift and low-lift. For low-lift valves (PSK type), the valve opens gradually, in proportion to the increase in pressure at the controlled point of the gas pipeline. Full-lift valves (SPPKR4R-16) open completely and sharply, with a jerk, and just as sharply, with the spool hitting the seat, they close when the pressure decreases. That is, the full-lift valve has a two-position position: closed and open.
When the maximum permissible setting pressure is reached, the PSK valve must open without fail until it is fully raised, and operate stably in the open position. The valve must close when the pressure drops to the nominal pressure or below it by 5% and ensure tightness. If there is a delay in closing the valve, the gas pressure in the network may drop significantly, which can lead to disruption of the system’s operating mode, as well as the release of a relatively large amount of gas into the atmosphere.
For low-lift PSKs, when closing the shutter after resetting required quantity gas, it is difficult to achieve tightness of the shutter, since this may require applying more force than in the “closed” mode. Such PSCs stop releasing gas only after the pressure decreases to 0.8–0.85% of the operating pressure, which leads to a constant or long-term release of gas into the atmosphere. The main advantage of membrane PSCs is the presence in their design of an elastic membrane that acts as a sensitive element. If in spring valves The spool performs the functions of both a sensing element and a shut-off element, while in diaphragm valves the spool performs only shut-off functions. The membrane makes it possible to increase the sensitivity of PSCs in general and expand the range of their use, including low gas pressure. PSK must ensure opening when the established operating pressure is exceeded by no more than 15%.
The choice of UCS design should be made in accordance with the throughput.
The amount of gas to be discharged by the PSK should be determined:
If there is a SCP in front of the pressure regulator according to the formula Q≥0.0005Qd, where Q is the amount of gas to be discharged by the SCP within an hour at t=0° C and Pbar=0.10132 MPa, m³/h; Qd - design capacity of the pressure regulator at t=0° C and Pbar=0.10132 MPa, m³/h;
in the absence of a slam-shut valve in front of the pressure regulator according to the formulas: for pressure regulators with a seat valve Q≥0.01Qd, for control valves Q≥0.02Qd.
Low-lift membrane and spring PSKs have a small throughput. Thus, the throughput capacity of SPPK4R-50-16 (seat diameter 30 mm) at an operating pressure of 0.125 MPa is 830 m³/h, and PSK-50S/125 (seat diameter 50 mm) is only 10 m³/h. This is explained by the low lifting height of the spool. The capacity of PSK-50 (KPS-50) valves with guide ribs at low pressure is: 0.5–3 m³/h, at average - 7–20 m³/h (at a pressure in the PSK inlet pipe of 1.15 set pressure) .
The throughput capacity of PSK-50 without guide ribs can be taken to be twice as large with the same parameters. In addition to these PSCs, relief valves can also be part of ( constituent element) combined gas pressure regulators.
