EA030669B1 - Gas compression method using a multi-stage piston-type compressor - Google Patents

Abstract

The invention is related to compressor building and can be used in creation of multi-stage piston-type compressors. A gas compression method using a multi-stage piston-type compressor consists in that gas is supplied to the first stage compressor cylinder, compressed to the pressure necessary to pump it from the first stage, and supplied to the sealed crankcase. Then, after levelling pressures of gases in the first stage cylinder and the crankcase, gas compressed in the first stage of the compressor is fed for suction to the cylinder of the second stage of the compressor, and after compression and pressurization is supplied from the second stage to the third stage. The third stage piston is mounted on the first stage piston, and after compression of gas in the third stage, it is supplied to the consumer. Increased pressure in the crankcase block compensates, largely or fully, for the forces acting on the pistons from the compression cavities. This makes it possible, without exceeding the nominal load on the crankshaft, to use cross-head-free differential pistons and, accordingly, to combine two or more stages in a single row. The compressor design is simplified, and its cost is reduced.

Description

The invention relates to the field of compressor engineering and can be used to create multi-stage piston compressors. A method of compressing gases using a reciprocating multi-stage compressor consists in the fact that gas is fed into the first-stage cylinder of the compressor, compressed to the pressure required for its injection from the first stage, and fed to a sealed crankcase. Then, after equalizing the pressures of the gases in the first stage cylinder and crankcase, the gas compressed in the first stage of the compressor is supplied to the second stage of the compressor for intake into the cylinder, which after compression and injection from the second stage is supplied to the third stage. The third-stage piston is mounted on the first-stage piston and after compression of the gas in the third stage is supplied to the consumer. The increased pressure in the crankcase substantially or completely compensates for the forces acting on the pistons from the side of the compression cavities. This makes it possible, without exceeding the rated load on the crankshaft, to use borderless differential pistons and, accordingly, combine two or more stages in the same row. Simplifies the device of the compressor and reduces its cost.

030669

The invention relates to the field of compressor engineering and can be used to create reciprocating multi-stage compressors for the chemical industry, gas filling compressor stations, cryogenic equipment, etc.

There is a method of operation of a multi-stage compressor, in which the cavity with a compressible gas is separated from the crankcase cavity, communicated with the atmosphere (Frenkel MI, Piston compressors. L .: Leningrad branch of the publishing house "Mashinostroenie", 1969, p. 65). The specified distinction is carried out with the help of glands installed on the rods connecting the crossheads with the pistons. In such compressors it is possible to install two compression cavities in the same row. As a rule, in one of them the compression process takes place during the forward movement of the crosshead, and in the second, during the return stroke. Accordingly, the piston force acting on the one hand is partially compensated by the force acting on the other hand, as a result of which the total piston force acting on the crankshaft is significantly reduced. At the same time, the location of two compression cavities in the same row reduces the size and weight of the compressor. Based on these advantages, such compressors are widely used.

The disadvantages of such compressors are the need for high-precision rods with a high hardness surface and special devices sealing these rods and separating the medium from the working gas and the air in the crankcase, as well as the need to install crossheads and connecting rods in each row. All this complicates the device and increases its cost.

Also widely known is the method implemented in a multi-stage compressor and adopted as the closest analogue to the claimed solution, which consists in filling the crankcase with working gas under a pressure equal to the first-stage suction pressure (Plastinin PI Piston compressors. Volume 2. Design Basics ; Constructions; 3rd ed., Revised and extra - Moscow: Kolos, 2008, p. 558). In this case, the shaft is sealed with an end-type gland with an oil seal. In such compressors, the crankcase communicates with the space in which the gas is sucked in by the first stage. As a result, gas that has flowed through the piston seals is fed to the compressor intake and compressed again. Accordingly, it eliminates the need to use special high-precision rods with gland seals and to install crossheads in each row. Also in compressors that use the above method, the crosshead is not installed on the first stage and often on the second. In the end, the design of the compressor is easier and cheaper.

The disadvantage of this method is the need for multiple rows, almost equal to the number of cylinder-piston groups, as well as the relatively high values of piston forces acting on the crankshaft, which reduces the reliability of its work and leads to the need to strengthen it, which generally complicates the design of the crank shaft. connecting rod mechanism.

The present invention is the implementation of multi-stage compression of gases using a simpler and cheaper design of the compressor.

The technical result of the present invention is to improve the reliability of the crankshaft of the compressor by creating a pressure force of gases acting on the piston casing from the crankcase, which largely or completely compensates for the forces acting on the pistons from the compression cavities.

The technical result is achieved by a method of compressing gases using a reciprocating multi-stage compressor, consisting in the fact that gas is fed into the first-stage cylinder of the compressor, is compressed to the pressure necessary for its injection from the first stage and fed to the sealed crankcase, then after pressure equalization of the gases in the cylinder the first stage and the crankcase gas, compressed in the first stage of the compressor, is fed to the suction in the cylinder of the second stage of the compressor, which after compression and discharge from the second stage serves in t etyu stage piston which is mounted on the piston of the first stage and after the gas compression in the third stage is fed to the consumer.

In the proposed method, the case is that the crankcase, sealed from the external environment, communicates precisely with the discharge line of the first compressor stage, and not directly with the space in which the gas supplied to the first compressor cylinder is located, as was the case with the closest analogue . As a result, the pressure in the crankcase is maintained equal to the discharge pressure of this first stage. The relatively high gas pressure in the crankcase creates a "gas backup" - the pressure force of gases acting on the piston bottoms from the crankcase and substantially or completely compensating for the forces acting on the pistons from the compression cavities. A significant reduction in piston forces allows the installation of pistons of two or more stages in the same row without exceeding the rated load on the crankshaft. In many cases, it becomes possible to abandon crossheads and use drift-free differential pistons, since the function of the guide for smaller pistons can be performed by larger diameter pistons, the piston force of which is partially or fully compensated by the high pressure in the crankcase. As a result, the use of this method greatly simplifies the design of the compressor and reduces its cost.

The invention is illustrated by the drawing, which shows a diagram of one of the options multistep 1 030669

chati compressor operating on the proposed method.

The compressor includes a crankshaft 1 and connecting rods 2, a cylinder 3 of the first stage, a suction valve 4 of the first stage, a piston 5 of the first stage, a pressure valve 6 of the first stage, a crankcase 7, a channel 8 connected to the crankcase 7, a heat exchanger 9, a piston 10 of the second stage, second stage suction valve 11, second stage cylinder 12, second stage injection valve 13, heat exchanger 14, third stage piston 15, third stage suction valve 16, third stage cylinder 17, third stage discharge valve, pipes 19 connecting the stu Yeni compressor, mechanical seal 20.

Using the above compressor design, the inventive method is implemented as follows. This three-stage compressor has pistons that make reciprocating movement in the cylinders due to the rotational movement of the crankshaft 1 and the connecting rods 2, which are movably connected to the shaft and the pistons. Gas is fed into the cylinder 3 of the first stage of the compressor through the suction valve 4. The cylinder 3 of the first stage is filled with gas as the piston 5 returns to this stage. At the beginning of the forward stroke of the piston 5, the suction valve 4 is closed, and the piston 5 compresses the gas to the pressure necessary for its injection from this stage as it moves forward. Next, the compressed gas flows through the discharge valve 6. At the beginning of the compressor operation, until the crankcase 7 is filled with gas compressed in the first compressor stage, the gas enters through the channel 8 into the crankcase 7 and at the same time, having passed the heat exchanger 9, to the second stage suction. After filling the crankcase 7 with gas compressed in the first stage (almost a couple of seconds after the compressor starts working), the gas enters only the second stage suction. As the return stroke of the piston 10 of the second stage through the suction valve 11, the cavity of the cylinder 12 of the second stage is filled with gas compressed in the first stage. During the forward stroke of the piston 10, the gas that has filled the cylinder 12 is compressed and subsequently injected through the discharge valve 13. Then this gas is cooled in the heat exchanger 14 and enters the suction of the third stage. In the process of the return stroke of the piston 15 of the third stage, through the suction valve 16 of this stage, the cylinder 17 of the third stage is filled with gas compressed in the second stage. At the beginning of the forward stroke of the piston 15, the suction valve 16 is closed. The piston 15 makes a translational motion, squeezing further gas. As the final pressure is reached, gas is injected through the discharge valve 18 to the consumer. The steps of the compressor are interconnected by pipes 19. The compressor shaft is sealed with a mechanical seal 20.

With this method, the gas pressure in the compressor crankcase is equal to the discharge pressure of the first stage. Accordingly, a pressure force constantly acts on the bottom of the piston, which is equal to the pressure force acting on the end of the piston at the end of the compression process and during the injection process. Since these forces act in opposite directions, they fully compensate each other, and the piston force acting on the crankshaft from the piston of the first stage 5 is zero. This circumstance allows the third stage piston 15 to be mounted directly on the first stage piston 5 without its own crosshead and connecting rod. The crankshaft and the connecting rod in this case are loaded only by the piston force of the third stage. The pressure of the gas in the crankcase also acts on the bottom of the second-stage piston 10, which results in a very significant reduction in the piston force of the second-stage, that is, the force acting on the crankshaft, which increases the reliability of its operation without complicating the design of the compressor.

As a result of using the proposed method, the number of rows is also reduced, the dimensions of the crankshaft, crankcase and compressor as a whole are reduced, the number of parts is reduced (for example, a separate crosshead and a connecting rod for the third stage are not used), etc. As a result, the compressor device is simplified and its cost is reduced.

Claims (2)

CLAIM The method of compressing gases using a reciprocating multi-stage compressor, which consists in the fact that gas is fed into the cylinder of the first stage of the compressor, compress it to the pressure necessary for its discharge from the first stage, and is fed into the sealed crankcase, then after equalizing the pressures of gases in the first stage cylinder and crankcase gas, compressed in the first stage of the compressor, is fed to the suction in the cylinder of the second stage of the compressor, which after compression and discharge from the second stage serves to the third stage, the piston of which is installed poured on the piston of the first stage, and after compression of the gas in the third stage serves the consumer. - 2 030669