Regulator safety devices and filters. Gas management of boiler systems Low pressure gas safety valve

Safety shut-off valves (SSV) are installed in front of the regulator (along the gas flow) to automatically cut off gas to the regulator in cases where its pressure deviates from the set upper or lower limit. Upper limit of SCP operation should not exceed the maximum operating gas pressure after passing through the regulator by more than 25%. Lower limit of SCP operation determined based on setup results gas equipment, based on the possibility of burners going out and flame slippage.

The signal about the deviation of gas pressure from the set value is sent to the slam-shut valve via impulse tube, connected to the outlet pressure gas pipeline, which causes the valve to operate.

The shut-off valve is installed on a horizontal section of the gas pipeline in front of the regulator. To avoid shaking, the shut-off valves are installed on a fixed support. The response accuracy of the shut-off valves installed in the hydraulic fracturing unit must be ±5% of the specified values ​​of the controlled pressure. Activation of the pressure regulator in the event of a gas supply interruption should be carried out after identifying the cause of the shut-off switch and taking measures to eliminate the malfunction.

The following types of PZK are found in operation: PK (discontinued), PKN (PKV), PKK-40, KPZ, etc.

Valves type PKN (PKV) - These are semi-automatic shut-off devices designed to hermetically shut off the supply of non-aggressive gases. The valve closes automatically when the controlled pressure exceeds the set upper or lower limits. The valve can only be opened manually. Spontaneous opening of the valve is excluded.

Valves of this type are produced with nominal diameters (D) 50, 80, 100, 200 mm in the following modifications: PKN - safety valve low controlled pressure; PCV - high controlled pressure safety valve.

The valve consists of a valve-type body with a seat, an intermediate head, a stamped head cover, a plunger with a rubber seal with a built-in bypass valve, a controlled pressure adjustment mechanism, a diaphragm drive, and an anchor-lever system.

In the open (cocked) state, the plunger and the lever connected to its rod are raised, the lever pin is engaged with the hook of the anchor lever. The lower end of the hammer rests against the protrusion of the anchor lever. The striker pin is engaged with a protrusion at the end of the rocker arm: the engagement itself is possible provided that the gas pressure under the membrane is within the setting range.

When the valve opens, the rod will first move, the bypass valve will open and the gas pressure in the body cavity will equalize, which will make it possible to open the main valve (without significant force). When the valve closes, the plunger sits on the seat, then, under the action of the lever, the bypass valve closes.

A mechanism for adjusting controlled pressure is placed inside the glass, rolled into the lid, and a membrane with a rod is clamped between the head and the lid. An adjusting screw is screwed into the threaded hole in the upper end of the membrane rod, onto which a plate is placed, resting on the protrusions of the lid cup. The tip of the pin rests in the end recess of the adjusting screw. A nut is screwed onto the threaded part of the stud, on the end of which a small spring rests, designed to adjust the lower limit of the controlled pressure. A large spring rests on the plate to adjust the upper limit of the controlled pressure. The force of the small spring is adjusted by moving the nut while rotating the upper pin, and the force of the large spring is adjusted by moving the nut while rotating the adjusting sleeve. A controlled pressure pulse enters under the membrane through the impulse tube.

If the gas outlet pressure exceeds the permissible upper limit, the membrane with the rod will rise and compress the large spring. The left end of the rocker arm will rise, the right end will disengage from the hammer pin. The hammer will fall and strike the end of the anchor arm, which will disengage with the weight arm and fall, causing the plunger to drop onto the seat. When the output pressure decreases below the limit set by the small spring, the diaphragm with the rod will begin to fall, the right end of the rocker will move up and disengage with the hammer pin. As a result, as in the previous case, the plunger will fall onto the seat and block the gas passage.

The gas inlet into the valve must correspond to the arrow cast on the body. The valve is designed for a maximum gas inlet pressure of 12 kgf/cm 2.

The PKV valve differs from the PKN valve in that it has a stronger spring and the presence of an additional disk that reduces effective area membrane, and the absence of a membrane plate. This allows you to configure the PCV to higher response pressure values ​​than the PCV.

The valve is adjusted by a gas equipment mechanic. First the valve is adjusted to the lower limit, and then to the upper limit. Checking the SCP response parameters must be performed at least once every three months, as well as upon completion of equipment repairs.

Operation of installations using gas fuel, service staff enterprises carry out production instructions, developed based on the instructions of the manufacturers, taking into account local conditions and approved by the chief engineer of the enterprise or the person entrusted with the responsibilities of the technical manager of the enterprise.

It is allowed to operate gas-using installations without constant supervision by operating personnel if they are equipped with an automation system that ensures trouble-free operation and emergency protection in case of malfunctions.

Signals about gas contamination and equipment malfunction, condition burglar alarm the premises in which it is located must be located at a control center or in a room with employees permanently present there who are able to send personnel to the specified address to take action or promptly transmit information to the organization with which the service contract is concluded.

The operating mode of gasified units must correspond to the maps (Table 9.1) approved by the chief engineer of the enterprise. Regime cards must be posted near the units and brought to the attention of operating personnel.

Basics purpose of the regime card - ensuring sustainable thermal regime gas-fired installation and economical combustion of fuel with a minimum excess air ratio.

For each gas-using installation, after testing it in different combustion modes to obtain different performance, the commissioning organization draws up a regime map for three or more modes, each of which has a strict relationship between the parameters.

Main settingsregime card

Let's list initial data when drawing up a regime map:

• - for steam boilers: steam production, steam pressure in the boiler, feed water temperature, fuel combustion heat ( Qh);
• - for hot water boilers: water temperature at the inlet and outlet of the boiler, water pressure at the inlet and outlet of the boiler, water flow passing through the boiler, heat of combustion of the fuel (Zn).

The remaining parameters of the regime map are determined by laboratory analyzes of the composition flue gases and calculations.

When lighting, turning off burners, or switching from one operating mode to another, personnel must strictly adhere to the combustion modes specified in the regime map.

Regime maps must be adjusted once every three years, as well as after repair of units.

Safety devices are intended to prevent pressure from increasing above a specified value and to prevent the movement of the medium in the direction opposite to the specified one. As safety valves check valves, shut-off valves, relief valves and high-speed valves are used.

Safety shut-off valves (SSV) are used to automatically stop the supply of gas to consumers in the event of a change in its pressure at a controlled point above specified limits. They are installed in the gas distribution unit (GRU), on gas distribution lines, in front of the burners of gas-consuming units.

The accuracy of the operation of the shut-off valve should be ±5% of the specified controlled pressure values ​​for the shut-off valve installed in the gas distribution unit, and ±10% for the shut-off valve in cabinet-type gas distribution units (GRU). Mainly for hydraulic fracturing (GRU) and large gas consuming units, safety shut-off valves are used. PCV valves and PKN with nominal diameters of 50, 80, 100 and 200 mm. The PCV valve membrane uses a stiffer spring, which allows it to be used on high-pressure gas pipelines.

Safety shut-off valve type PKN (B) (Fig. 4.3.) consists of a cast iron body of 1 valve type, a membrane chamber, a superstructure head and a lever system. Inside the body there is a seat and a valve 9. The valve stem is connected to a lever 14, one end of which is hinged inside the body, and the other with a load is brought out. To open valve 9 using lever 14, the rod is first raised slightly and held in this position, this opens a hole in the valve and the pressure difference before and after it decreases. The lever with the load 14 is brought into engagement with the anchor lever 15, which is hinged on the body. The impact hammer 17 is also hinged and located above the arm of the anchor lever. Above the body, under the superstructure head, there is a membrane chamber into which gas is supplied from the working gas pipeline under the membrane. On the top of the membrane there is a rod with a socket into which the rocker arm 16 fits with one arm. The other arm of the rocker arm engages with the pin of the impact hammer.

Fig.4.3. Safety shut-off valve type PKN (B):

Safety relief valves.

Safety relief valves are activated when the operating pressure increases to +15%, by releasing gas into the atmosphere.

As one of the types pipeline fittings safety valve(Fig.4.4) is intended for automatic protection technological system and pipelines from an unacceptable increase in pressure of the working medium. There are spring and lever safety valves.

According to the method of releasing the working medium, they are divided into a safety valve, one operating without backpressure, and a relief valve. work environment into the atmosphere, and a safety valve with back pressure that discharges the working medium into the pipeline.

Rice. 4.4. Safety locking PKN valves(PKV):

1 – fitting, 2.4 – levers, 3, 10 – shifters, 5 – nut, 6 – plate, 7.8 – springs, 9 – drummer, 11 – rocker arm, 12 – membrane

Also, the spring safety valve can be equipped with a manual detonation lever to check its functionality or manually release the working medium.

The safety valve (relief valve) is designed to protect equipment from unacceptable excess pressure above the established one. Safety valves are used on tanks, boilers, containers, vessels and pipelines for automatic or manual release of pressure into the atmosphere or outlet pipeline. After the pressure decreases to the required limit, the safety valve stops discharging the medium. Safety valves are designed for liquid and gaseous, chemical or petroleum working media. Tightness standards according to GOST 9789-75.

The fast-acting shut-off valve is designed to automatically stop the gas supply to consumers when the controlled pressure increases or decreases from specified limits.

Brief description of the design and operation of the bullpen valve

The safety shut-off valve in accordance with Figure 1 consists of a cast body 1. Inside the body there is a seat, which is closed by valve 2 with a rubber seal. Valve 2 is mounted on axis 3, which is located in housing 1. Springs 4.5 are installed on axis 3, one end of which rests against housing 1, the other against valve 2. At the end of axis 3, which extends outward, a rotary lever 6 is rigidly fixed, which rests on the lever 16. A control mechanism 7 is attached to the body 1, which has a membrane 8,

rod 9 and tip 15 rigidly fixed to rod 9. Tip 15 engages with stop 12 of lever 16 and prevents it from turning. The membrane is balanced by controlled pressure and springs 10,11, the forces of which are regulated by bushings 13, 14.

The SCP valve operates as follows: Controlled pressure is supplied to the submembrane cavity of the control mechanism 7, causing the tip 15 to be positioned in the middle position. When the pressure in the submembrane cavity increases or decreases beyond the adjustment limits, the tip 15 moves to the left or right, and the stop 12 mounted on the lever 16 disengages with the tip 15, releases the interconnected lever 16 and the rotary lever 6 and allows the axis 3 turn around. The force from the action of springs 4.5 is transmitted to valve 2, which closes the gas passage.

Bringing valve 2 into operating condition after actuation is done manually by turning lever 6, while the bypass valve built into valve 2 opens first. After equalizing the pressure before and after valve 2, the lever 6 is further raised until it engages with the lever 16 and fixes them with the tip 15, while the valve 2 must be held in open position.

Setting up the safety shut-off valve of the bullpen.

1. Adjust the upper limit of valve actuation by changing the tension of spring 11 by rotating sleeve 14. During adjustment, the pressure in the impulse tube should be maintained slightly below the set upper limit, and then slowly increase the pressure and make sure that the valve operates at the set upper limit.

2. Adjust the lower limit of valve operation by changing the tension of spring 10 by rotating sleeve 13.

During adjustment, the pressure in the impulse tube should be maintained slightly above the set lower limit, and then slowly decrease the pressure and ensure that the valve operates at the set lower limit.

3. After completing the adjustment, increase the pressure in the impulse tube and make sure that the valve operates again with the upper limit set.

5 Providing first aid to a victim of carbon monoxide poisoning

Symptoms:

Muscle weakness appears

Dizziness

Noise in ears

Drowsiness

Hallucinations

Loss of consciousness

Convulsions

Providing assistance:

Stop the flow of carbon monoxide

Remove the victim to fresh air

If the victim is conscious, lay him down and ensure rest and continuous access to fresh air.

If there is no consciousness, it is necessary to begin closed cardiac massage and artificial respiration until the ambulance arrives or until consciousness is gained.

Safety devices are divided into shut-off and relief devices. Safety shut-off devices (shut-off valves) are devices that ensure the cessation of gas supply, in which the speed of bringing the working element to closed position is no more than 1 second. Safety relief devices (relief valves) are devices that protect gas equipment from an unacceptable increase in gas pressure in the network.

Safety shut-off devices are installed in front of the gas pressure regulator. Their membrane head is connected to a final pressure gas pipeline through an impulse tube. When the final pressure increases above the established standards, the shut-off valves automatically cut off the gas supply to the regulator.

Safety-relief devices used in hydraulic fracturing ensure the release of excess gas in the event of a leaky shut-off valve or regulator. They are mounted on the outlet pipe of the final pressure gas pipeline, and the outlet fitting is connected to a separate spark plug. If the technological process of gas consumers involves continuous operation gas burners, then the SCP is not installed, but only the PSK is mounted. In this case, it is necessary to install gas pressure alarms that notify if the gas pressure increases above the permissible value. If the gas distribution center (GRU) supplies dead-end facilities with gas, then the installation of a pressure protection valve is necessary.

Let's look at the most common types of locking and safety devices.

Low pressure protection valve (PKI) and high pressure protection valve (PKV) control the upper and lower limits of the gas outlet pressure; are issued with conditional passages 50, 80, 100 and 200 mm. The PKV valve differs from the PKN valve in that it has a smaller active membrane area due to the imposition of a steel ring on it.

The schematic diagram of these valves is shown in the figure below.

Safety shut-off valves PKN and PKV

1 - fitting; 2, 4 - levers; 3, 10- pins; 5 - nut; 6 - plate; 7, 8 - springs; 9 - drummer; 11 - rocker arm; 12-membrane

In the open position, the valve is held by a lever, which is fixed in the upper position by the pin with the hook of the anchor lever; The striker rests against the rocker arm using a pin and is held in a vertical position.

The final gas pressure pulse is supplied through the fitting into the sub-membrane space of the valve and exerts back pressure on the membrane. A spring prevents the membrane from moving upward. If the gas pressure increases above normal, the membrane will move up and the nut will move up accordingly. As a result, the left end of the rocker will move up, and the right end will move down and disengage with the pin. The hammer, freed from engagement, will fall and strike the end of the anchor lever. As a result, the lever is disengaged from the pin, and the valve will block the gas passage. If the gas pressure drops below permissible norm, then the gas pressure in the sub-membrane space of the valve becomes less than the force created by the spring resting on the protrusion of the diaphragm rod. As a result, the membrane and rod with nut will move down, dragging the end of the rocker down. The right end of the rocker arm will lift up, disengage from the pin and cause the firing pin to fall.

The following setup order is recommended. First, the valve is adjusted to the lower response limit. During adjustment, the pressure behind the regulator should be maintained slightly above the set limit, then, slowly reducing the pressure, make sure that the valve operates at the set lower limit. When setting the high limit, you must maintain the pressure slightly above the set low limit. After completing the adjustment, you need to increase the pressure to make sure that the valve operates exactly at the specified upper limit of the permissible gas pressure.

Safety shut-off valve PKK-40M.

In the cabinet GRU (figure below) a small-sized PZK PKK-40M is installed. This valve is designed for an inlet pressure of 0.6 MPa.

Wiring diagram for cabinet GRU with PZK PKK-40M

A - circuit diagram: 1 - inlet fitting; 2 - inlet valve; 3 - filter; 4 - fitting for pressure gauge; 5 - valve PKK-40M; 6 - regulator RD-32M (RD-50M); 7 - fitting for measuring final pressure; 8 - outlet valve; 9 - discharge line of safety valves built into the regulators; 10 - impulse line final pressure; 11 - impulse line; 12 - fitting with tee; 13 - pressure gauge; b - section of the PKK-40M valve: 1, 13 - valves; 2 - fitting; 3, 11 - springs; 4 - rubber seal; 5, 7 - holes; 6, 10 - membranes; 8 - starting plug; 9 - pulse chamber; 12 - rod

To open the valve, the trigger plug is unscrewed, after which the valve's impulse chamber communicates with the atmosphere through the hole. Under the influence of gas pressure, the membrane, rod and valve move upward, and when the membrane is in the uppermost position, the hole in the valve rod is covered with a rubber seal and the flow of gas from the body into the pulse chamber stops. Then the starting plug is screwed in. Through open valve the gas enters the pressure regulators and through the impulse tube into the chamber. If the gas pressure behind the regulators increases above the established limits, the membrane, overcoming the elasticity of the spring, will move upward, as a result of which the hole, previously covered with a rubber seal, will open. The upper membrane, rising, rests its disk against the lid, and the lower one, under the action of the spring and the mass of the valve with the rod, falls down, and the valve closes the gas passage.

Safety shut-off valve KPZ(picture below) is installed in front of the gas pressure regulator. Its upper response limit should not exceed the nominal operating pressure after the regulator by more than 25%, and the lower response limit is not established in the rules, since this value depends on the pressure loss in the supply gas pipeline and on the control range.

Safety shut-off valve KPZ

1 - body; 2 - valve with rubber seal; 3 - axis; 4, 5 - springs; 6 - lever; 7 - control mechanism; 8 - membrane; 9 - rod; 10, 11 - adjustment springs; 12 - emphasis; 13, 14 - bushings; 15 - tip; 16 - lever

The working principle of the bullpen is as follows:

• in the operating position, the valve levers are engaged and in stop with the tip of the diaphragm head rod, and the gearbox valve is open;
• when the gas pressure changes above or below the permissible value, the membrane bends and moves the rod according to the change in pressure to the right or left along with the tip;
• the lever comes out of contact with the tip , in this case, the engagement of the levers is disrupted and, under the action of springs, the axis closes the valve;
• the inlet gas pressure enters the valve and presses it more tightly to the seat.

Relief safety devices, unlike shut-off valves, do not shut off the gas supply, but release part of it into the atmosphere, thereby reducing the pressure in the gas pipeline.

There are several types of discharge devices, different in design, principle of operation and scope of application: hydraulic, lever-load, spring and membrane-spring. Some of them are used only for low pressure(hydraulic), others - for both low and medium pressure (diaphragm-spring).

Safety relief valve PSK. The membrane-spring ISK (figure below) is installed on gas pipelines of low and medium pressure. Valves PSK-25 and PSK-50 differ from each other only in dimensions and throughput.

Safety relief valve PSK

1 - adjusting screw; 2 - spring; 3 - membrane; 4 - seal; 5 - spool; 6 - saddle

Gas from the gas pipeline after the regulator enters the valve membrane. If the gas pressure is greater than the spring pressure from below, then the membrane moves down, the valve opens and the gas is released. As soon as the gas pressure becomes less than the spring force, the valve closes. The compression of the spring is adjusted with a screw at the bottom of the housing. To install the PSK on low or high pressure gas pipelines, appropriate springs are selected.

Spool relief valve PSK-25 has the shape of a cross and moves inside the seat. In PSK-50, the valve spool is equipped with profiled windows. The reliability of the PSK valve largely depends on the quality of the assembly.

During assembly you must:

• Having cleaned the valve device from mechanical particles, make sure that there are no scratches or nicks on the edge of the seat and the sealing rubber of the spool;
• achieve alignment of the relief valve spool with the central hole of the membrane;
• To check the alignment, loosen or remove the spring and, by pressing the spool through the reset hole, make sure that it moves freely inside the seat.

Safety relief valve PPK-4.

Spring loaded safety valve, medium and high pressure PPK-4 (figure below) is produced by industry with nominal bores of 50, 80, 100 and 150 mm. Depending on the diameter of the spring 3, it can be adjusted to a pressure of 0.05-2.2 MPa.

Safety relief valve PPK-4

1 - valve seat; 2 - spool; 3 - spring; 4 - adjusting screw; 5 cam

Gas filters.

In the GRU with conditional passage up to 50 mm install corner mesh filters(figure below), in which the filter element is a cage covered with a fine mesh. In hydraulic fracturing with regulators with a nominal bore of more than 50 mm, cast iron hair filters(picture below). The filter consists of a housing, a cover and a cassette. The cassette holder is covered on both sides metal mesh, which traps large particles of mechanical impurities. Finer dust settles inside the cassette on the pressed fiber, which is lubricated with special oil.

Gas filters

a - corner mesh; b - hairline: 1 - body; 2 - cover; 3 - mesh; 4 - pressed fiber; 5 - cassette

The filter cassette resists the gas flow, which causes a pressure difference before and after the filter. An increase in the gas pressure drop in the filter to more than 10,000 Pa is not allowed, as this may cause fiber carryover from the cassette.

To reduce pressure drops, it is recommended to periodically clean the filter cassettes (outside the hydraulic fracturing building). The internal cavity of the filter should be wiped with a rag soaked in kerosene.

Depending on the type of regulators and gas pressure used various designs filters.

The figure below shows the design of a filter intended for hydraulic fracturing, equipped with RDUK regulators. The filter consists of a welded body with connecting pipes for gas inlet and outlet, a cover and a plug. On the gas inlet side, a metal sheet is welded inside the housing, protecting the mesh from direct ingress of solid particles. Solid particles coming with the gas, hitting the metal sheet, are collected in the lower part of the filter, from where they are periodically removed through the hatch. Inside the case there is a mesh cassette filled with nylon thread.

Welded filters

a - filter for RDUK regulators: 1 - welded housing; 2 - top cover; 3 - cassette; 4 - hatch for cleaning; 5 - bumper sheet; b - filter revision: 1 - outlet pipe; 2 - mesh; 3 - body; 4 - cover

The remaining solid particles in the gas stream are filtered in a cassette, which is cleaned as necessary. To clean and rinse the cassette, the top filter cover can be removed. Differential pressure gauges are used to measure pressure drop. Additional filtering devices are installed in front of the rotary counters - a revision filter (figure above).