RU2588347C2 - Method of operating piston pump-compressor and device therefor - Google Patents

Abstract

FIELD: pumps.

SUBSTANCE: invention relates to pump and compressor industry and can be used in designing piston machines of volumetric action, intended for compression and delivery to consumer simultaneously or alternately liquids and gases. Method of operating piston pump-compressor comprises alternating suction, compression and supply to consumer of gas from above-piston cavity, as well as suction and injection of liquid in under-piston cavity and its supply to consumers. Compressed gas is supplied to consumers through automatic pressure valve and gas delivery line. Fluid supply to consumers is carried out through a fluid delivery line. Resistance of gas delivery line gas varies in accordance with pressure of fluid injection. Pump-compressor comprises cylinder 1 with piston 2, dividing cylinder into gas 3 and fluid 4 cavities. Said cavities are connected by gas suction lines 5 and fluid via suction self-actuated valves 6 and 10 and gas 7 and fluid 11 delivery lines through injection self-actuated valves 9 and 12. Gas discharge valve 9 has a lift limiter made in form of bellows 17 with end part facing towards gas pressure valve 9, and internal cavity of which is connected to liquid delivery line 11. In gas delivery line 7 there can be installed spring-loaded piston 20, arranged by one end in cylinder 21, connected with fluid pressure line, and by other end is arranged directly in pipeline of gas delivery line 7 with possibility of partial overlapping of said line. Action of spring 19 is directed against action of pressure in fluid delivery line. Similarly pump-compressor operates, if for any reasons (rapture of pressure line, increased consumption of consumer gas) pressure in gas delivery line considerably decreases against rated value.

EFFECT: during start-up of pump-compressor conditions are not created for occurrence of hydraulic shock due to penetration of fluid from chamber 4 into chamber 2 with no pressure in gas delivery line 7.

5 cl, 2 dwg

Description

The invention relates to the field of pump and compressor engineering and can be used to create reciprocating volumetric machines designed to compress and supply to the consumer simultaneously or alternately liquids and gases.

There is a known method of operation of a piston pump-compressor, which consists in alternately compressing and supplying a consumer with gas from a supra-piston cavity, compressing fluid in a sub-piston cavity and supplying it to a consumer (see RF patent No. 118371, MKI F04B 19/06 of 20.07.2012).

There is also a known method of operation of a piston pump-compressor, which consists in alternately sucking, compressing and supplying gas to the consumer from the supra-piston cavity, and sucking and compressing liquid in the sub-piston cavity and supplying it to the consumer, the compressed gas being supplied to the consumer through a self-acting discharge valve and gas injection line and the fluid is supplied to the consumer through the fluid injection line (see, for example, RF Patent No. 125635 for the utility model “Piston Pump-Compressor”, IPC F04B 19/06, application 24.09.2 012, publ. 03/10/2013).

A disadvantage of the known methods is the high likelihood of water hammer, which arises due to the fact that at the initial moment of starting the pump-compressor, when there is still no excess pressure in the gas injection line (equal to atmospheric), and there is already liquid pressure in the liquid discharge line, the liquid returns - the translational movement of the piston through the seal between the piston and the cylinder penetrates in large quantities into the gas cavity of the unit, and as soon as its volume exceeds the dead volume of the gas cavity, a water hammer occurs. This is especially true when the pressure of the liquid in the liquid discharge line substantially exceeds atmospheric pressure. As a result of water hammer, the valve box of the gas cavity is destroyed and the unit breaks down with a complete loss of operability. A similar phenomenon occurs when, for some reason (damage to the gas discharge pipe, excessively high gas consumption), the pressure in the discharge gas pipe becomes very low.

An object of the invention is to increase the efficiency of the compressor pump by eliminating the possibility of water hammer during its start-up and operation at reduced gas pressure.

The specified technical problem is solved by the fact that in the known method of operation of the pump-compressor according to the invention, the resistance of the gas injection line is changed in accordance with the liquid injection pressure.

This change in resistance can be carried out by acting on the gas discharge valve, changing the value of its opening, or by changing the flow area of the gas injection line.

In a piston pump-compressor for implementing the above method, comprising a cylinder with a piston installed therein, dividing the cylinder into gas and liquid cavities, respectively connected to gas and liquid suction lines through self-acting suction valves, and to gas and liquid discharge lines through self-acting pressure valves moreover, the gas pressure valve has a lift limiter, according to the invention, this lift limiter is made in the form of a bellows with the end part facing to the side gas discharge valve, and the internal cavity of which is connected to the liquid discharge line. A change in the resistance of the gas discharge line can also be created in the known pump-compressor by installing a spring-loaded piston in this line, placed at one end in a cylinder connected to the liquid discharge line, and the other end of which is placed directly in the pipeline of the discharge line with the possibility of partially overlapping this line, and the action of the spring is directed against the action of pressure in the liquid discharge line.

The invention is illustrated by the example of the operation of two structural options of pump-compressors, schematically shown in the drawings.

In FIG. 1 shows a diagram of a piston pump-compressor with a device for changing the stroke of the shut-off element of a gas discharge valve to change the hydraulic resistance of the discharge line.

In FIG. 2 shows a diagram of a piston pump-compressor with a device for changing the hydraulic resistance of the discharge line by installing a spring-loaded piston partially overlapping the section of the discharge line.

The compressor pump (Fig. 1) comprises a cylinder 1 with a piston 2 installed in it with a clearance, dividing the cylinder 1 into a gas 3 and a liquid 4 cavity, which have a gas suction line 5 connected to the gas cavity 3 through a self-acting valve 6, and with a gas injection line 7 through a self-acting valve 8, a liquid suction line 9 connected to the cavity 4 through a self-acting valve 10, and a liquid discharge line 11 connected to the cavity 4 through a self-acting valve 12. A receiver 13 with a pressure gauge 14 is built into the gas injection line 7, and 14 valve m 15, through which gas is supplied to the consumer. An air cap 16 is installed on the fluid injection line 11, which is part of the fluid injection line 11 and reduces the pressure pulsations of the injected fluid, the upper (gas) part of which is connected via an air line to the internal cavity of the lift stop 17 of the pressure valve 8. The lift stop 17 is made in the form of a bellows with the end part facing towards the valve 9. The plate 18 with the hole into which the valve 8 enters serves to restrict the movement of the end part of the bellows 17 towards the valve 8, while ensuring the minimum flow area of valve 8 is reached when the end of the bellows 17 is in the lowest position when it is rested against the plate 18. In this design, the change in hydraulic resistance in the gas discharge line 7 is organized by changing the force acting on the valve 8 towards its closing side of the line fluid injection 11 - the greater this force, the higher the hydraulic resistance of the gas injection line 7.

In the compressor pump shown in FIG. 2, a piston 20, spring-loaded with a compression spring 19, is installed in the gas injection line 7 and is located at one (lower) end in the cylinder 21 connected to the air cap 16 of the discharge line 17 and the other (upper) end is directly in the pipeline of the gas injection line 7, this upper end with its end partially overlaps the discharge line 7, for which a counter boss 22 is mounted opposite the end, with a piston 20 limiter in the form of a protrusion 23. The action of the spring 19 is directed against the action of the fluid pressure on the pore tire from the discharge line side 11. In this design, the change in hydraulic resistance in the gas discharge line 7 is organized by exposing the piston 20 to a liquid pressure with the formation of a variable resistance gap — the larger the difference between the liquid pressure and the gas pressure, the greater the hydraulic resistance of the gap and therefore , the greater the hydraulic resistance of the gas injection line 7.

The method of operation of the piston pump compressor is as follows (Fig. 1). When starting the compressor pump, as a rule, the hydraulic line 11 is already under discharge pressure due to the low compressibility of the liquid and its high viscosity, and the gas discharge line 7 is under atmospheric pressure due to the inevitable leakage of a low-viscosity working fluid - gas - through the valve 15 and valve 8 during the stop of the compressor pump, which can be indefinitely long.

With the reciprocating movement of the piston 2, the volume of the liquid cavity 4 alternately increases (the valve 10 opens and the liquid is sucked from the suction line 9) and decreases (the liquid is pumped through the valve 12 to the discharge line 11) and supplied to the consumer under pressure. The pulsation of the fluid pressure that occurs due to its non-uniform supply is damped by gas under the pressure of the fluid injection in the upper part of the air cap 16. When the piston 2 is down, when the fluid is compressed in the chamber 4 and pumped to the consumer, the liquid from the chamber 4 rises in the gap between the piston 2 and the cylinder 1.

At the same time, due to the alternating change in the volume of the gas cavity 3 with its increase, gas is sucked in through the valve 6 from the suction line 5, it is compressed and supplied to the consumer through the valve 8, the discharge line 7 with the receiver 13. Since at the initial moment of operation of the pump-compressor in the receiver 13, the pressure is equal to atmospheric, the valve 15 is closed and the operator opens it only after the pressure gauge 14 shows the nominal gas discharge pressure due to the work of the gas consumer.

Thus, at the very first strokes of the piston 2, a nominal fluid pressure is set in the fluid injection line 11, and almost atmospheric pressure remains in the gas injection line 7. In this case, the pressure from the liquid injection line 11 through the cap 16 and the gas located in its upper part is supplied to the cavity of the bellows 17, which expands without backpressure from the gas injection line 7, abuts against the plate 18, restricting its movement, and its end part restricts the ability to lift valve 8, in connection with which valve 8 opens to a minimum value (becomes "covered"), which leads to an increase in its hydraulic resistance and an increase in pressure in the chamber 3 during the course of the piston 2 during compression discharge (upward stroke). This increased pressure "squeezes" the liquid from the gap between the piston 2 and the cylinder 1 down towards the chamber 4, preventing it from entering the chamber 3 and creating conditions for the occurrence of water hammer.

The gas passing through the “covered” valve 8 enters the receiver 13, gradually increasing the pressure in it from the stroke to the stroke of the piston 2, while the pressure in the discharge line 7 increases, acting on the lower end of the bellows 17. Gradually, the pressure in the discharge line 7 increases to such a value when the pressure drop between the cavity of the bellows 17 and the gas injection line 7 becomes small and the bellows 17, under the action of the elastic forces of its material, moves away from the plate 18, increasing the possible opening of valve 8. This process increases with pressure tions in gas discharge line 7 continues as long as the bellows 17 completely frees the valve 8, which runs in normal mode. At this time, the gas pressure in the receiver 13 becomes equal to the nominal gas injection pressure and the operator opens the valve 15, the supply of compressed consumer gas begins.

In the event that for some reason (increased gas consumption, rupture or damage to the gas discharge line 7), the gas injection pressure decreases significantly, the threat of water hammer again arises, which is prevented by the fact that under the influence of a large pressure drop across the bellows 17 it presses valve 8 to the seat, increasing the resistance of the discharge line 7 in the area between the valve 8 and the receiver 13.

The operation of the structure shown in FIG. 2 occurs similarly to the above. Here, the increased gas pressure in the cavity 3 (during the start-up of the compressor pump or when the gas pressure in the discharge line 7 drops during the operation of the compressor for the above reasons) is ensured by reducing to the minimum the passage section of the gap formed by the upper end face of the raised piston 20 and the surface bosses 22. The minimum section of the gap (regardless of the pressure difference between the discharge lines 11 and 7) is provided by the protrusion 23. During the start-up of the pump-compressor or when the gas pressure drops compared to the pressure w pressure under the action of a pressure differential between lines 11 and 7 and, accordingly, on the piston 20, this piston rises and abuts against the protrusion 23. When the pressure in line 7 increases, the pressure drop on the piston 20 decreases and the spring 19 pushes it away, the hydraulic resistance of the gap between the end face of the piston 20 and the boss 22 is reduced.

Thus, due to the presence of variable hydraulic resistance in the gas discharge line during the start-up of the compressor pump, from the very beginning of its operation, the pressure is created in the gas cavity to prevent liquid from entering the gas cavity, which helps prevent the possibility of water hammer and increase pump operability -compressor. If the gas pressure drops due to an increase in its consumption by the consumer or if the discharge line breaks down (damage, rupture), which causes a pressure drop in the gas injection line 7, the gas pressure in the cavity 3 is automatically maintained, preventing a large amount of liquid from entering the cavity 4 into the cavity 3 through clearance between piston 2 and cylinder 1, which also prevents water hammer.

Thus, the technical task of the invention is to increase the efficiency of the pump-compressor by eliminating the possibility of water hammer during its start-up and operation at reduced gas pressure - is fully implemented.

Claims (5)

1. The method of operation of a piston pump-compressor, which consists in alternately sucking, compressing and supplying gas to the consumer from the supra-piston cavity and sucking and pumping liquid into the sub-piston cavity and supplying it to the consumer, the compressed gas being supplied to the consumer through a self-acting pressure valve and a gas injection line, and the liquid is supplied to the consumer through the liquid injection line, characterized in that the resistance of the gas injection line is changed in accordance with the injection pressure dots. 2. The method of operation of the piston pump-compressor according to claim 1, characterized in that the change in the resistance of the gas injection line is carried out by acting on the gas discharge valve. 3. The method of operation of a piston pump-compressor according to claim 1, characterized in that the change in the resistance of the gas injection line is carried out by changing the flow area of the discharge line. 4. A piston pump-compressor for implementing the method according to claim 1, comprising a cylinder with a piston installed therein, dividing the cylinder into gas and liquid cavities, respectively connected to gas and liquid suction lines through self-acting suction valves and to gas and liquid injection lines through self-acting discharge valves, the gas discharge valve having a lift limiter, characterized in that the lift limiter of the gas discharge valve is made in the form of a bellows with an end part, arr tipped towards the gas discharge valve, and the internal cavity of which is connected to the liquid discharge line. 5. A piston pump-compressor for implementing the method according to claim 1, comprising a cylinder with a piston installed therein, dividing the cylinder into gas and liquid cavities, respectively connected to gas and liquid suction lines through self-acting suction valves and to gas and liquid injection lines through self-acting discharge valves, characterized in that a spring-loaded piston is installed in the gas injection line, placed at one end in a cylinder connected to the liquid discharge line, and the other end of which eschen directly into the gas discharge pipe, with partial overlapping of the line, wherein the spring action directed against the action of pressure in the fluid discharge line.

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