Liquid-surge-proof compressor cylinder structure, compressor, and wellhead natural gas compression method

Abstract

The present invention discloses a liquid-surge-proof compressor cylinder structure, a compressor, and a wellhead natural gas compression method, which relate to the technical field of compressors. The cylinder structure includes a cylinder barrel and a piston ring assembly. The cylinder barrel is provided with a piston chamber and a partition. The partition separates the piston chamber into a working chamber and a buffer chamber. The piston ring assembly is provided in the working chamber and further includes a connecting channel. The connecting channel is used to connect the working chamber and the buffer chamber on both sides of the partition. The partition is configured so that when the pressure difference between the working chamber pressure and the buffer chamber pressure exceeds a set threshold, the partition is fixed in the piston chamber under the pressure difference on both sides, and the partition can move toward the side where the buffer chamber is located under the pressure difference. The compressor includes the cylinder structure, and the compression method is implemented based on the cylinder structure. This solution uses the method of expanding the cylinder clearance volume to reduce the maximum pressure in the cylinder when liquid hammer occurs, which can effectively optimize the response speed of the clearance volume expansion process.

Description

Technical Field

[0001] The present invention relates to the technical field of compressors, and in particular to a liquid-surge-proof compressor cylinder structure, a compressor, and a wellhead natural gas compression method. Background Art

[0002] The role of a wellhead natural gas compressor in natural gas extraction is to pressurize natural gas from the wellhead and deliver it to the exhaust pipeline. In the prior art, positive displacement compressors, such as piston compressors, are often used for this purpose, due to the required flow rate and pressure after pressurization.

[0003] There are significant differences in the working conditions between wellhead natural gas compressors and natural gas compressors in other situations, including the medium characteristics of the processed medium. For example, in addition to gas phase components, well flow may also contain liquid water and high-concentration water vapor. The sources of the liquid water (wellhead water) include edge water or bottom water propulsion, interlayer water channeling, fracturing fluid backflow, etc. For the wellhead, current technology has control measures from the aspects of production control and water plugging control. For the compressor, in order to prevent liquid hammer, a separator (solid / liquid / gas three-phase separator) is set on the inlet side of the compressor for control. In the existing technology, wellhead water discharge monitoring measures such as downhole pressure gauges, hydroacoustic intensity monitoring sensors, and gas-liquid ratio sensors can be used to predict wellhead water discharge in advance. Through early control, the risk of liquid water being sucked into the compressor by the wellhead and causing liquid hammer can be reduced. However, when a large amount of water is discharged suddenly or the wellhead separator fails, the compressor may still directly suck in liquid water and cause liquid hammer in the compressor. When liquid hammer occurs, depending on the water content in the piston compression chamber, possible situations may include instantaneous strong impact, resulting in instantaneous damage to the piston, connecting rod, cylinder body, cylinder head, etc.

[0004] In the prior art, in order to avoid extreme fluid impact events such as liquid hammer on the compressor, in addition to the isolation protection measures proposed above to effectively separate liquid water before the medium enters the compressor, a technical solution such as patent application number CN202310457006.0 (Name: A cylinder structure for preventing liquid hammer in a reciprocating piston compressor and its working method) has also been proposed. In this solution, internal pressure is used to open a pressure relief channel to release internal pressure, thereby achieving the purpose of protecting the compressor. However, the physical essence of this method is the same as the way a conventional exhaust valve on a compressor is used to relieve pressure. When faced with instantaneous liquid hammer, it is impossible to effectively complete the pressure relief before the liquid hammer produces a strong impact (this is also the reason why the cylinder structure has an exhaust valve, but the exhaust valve cannot prevent the occurrence of liquid hammer).

[0005] The anti-liquid hammer technology of the compressor cylinder structure supplements the anti-liquid hammer function of the separator in the compressor system. Further optimizing the anti-liquid hammer technology of the compressor cylinder structure is undoubtedly of great significance to promoting the orderly and efficient production of natural gas at the wellhead. Summary of the Invention

[0006] In response to the aforementioned issue of optimizing the anti-liquid hammer technology for compressor cylinder structures, the present invention provides an anti-liquid hammer compressor cylinder structure, a compressor, and a wellhead natural gas compression method. This solution uses a method of expanding the cylinder clearance volume to reduce the maximum pressure in the cylinder when liquid hammer occurs. This technical solution can effectively optimize the response speed of the clearance volume expansion process.

[0007] To address the above-mentioned problems, the present invention provides a liquid-surge-proof compressor cylinder structure, a compressor, and a wellhead natural gas compression method, which solve the problems through the following technical points: the liquid-surge-proof compressor cylinder structure includes a cylinder barrel and a piston ring assembly. The cylinder barrel is provided with a piston chamber, and further includes a partition fixed inside the piston chamber. The partition separates the piston chamber into a working chamber and a buffer chamber in the axial direction of the piston chamber. The piston ring assembly is disposed in the working chamber. The structure also includes a communication channel provided on the cylinder barrel and / or the partition, and the communication channel is used to achieve mutual communication between the working chamber and the buffer chamber on both sides of the partition.

[0008] The partition is configured such that when the pressure difference between the working chamber pressure and the buffer chamber pressure exceeds a set threshold, the fixed relationship of the partition in the piston chamber is destroyed under the pressure difference on both sides of the partition, and the partition can move toward the side where the buffer chamber is located under the pressure difference.

[0009] This solution is intended to address the following issues: For liquid water that has entered the compression chamber of the compressor (i.e., the working chamber mentioned above) or liquid water formed in the compression chamber, the existing method of using the internal pressure in the compression chamber to push open the pressure relief channel requires overcoming the mechanical inertia of the valve core, spring, etc. During the process of continuous pressure increase in the compression chamber, the pressure relief channel is not opened in time due to the above mechanical inertia. Especially when the liquid water occupies a large volume in the compression chamber, the rapidly increasing internal pressure in the compression chamber will still cause severe liquid hammer in the cylinder structure, resulting in direct damage to compressor parts or accelerated part fatigue. The high failure rate of the compressor cylinder structure seriously affects the orderly and efficient production of wellhead natural gas.

[0010] This solution utilizes the connecting effect generated by the connecting channel to reduce the pressure difference between the working chamber and the buffer chamber on both sides of the partition, so as to use a thinner partition to form a working chamber pressure boundary. When liquid hammer occurs in the working chamber, the thinner partition has the characteristic of smaller mechanical inertia, so that when the partition moves toward the buffer chamber to expand the working chamber volume, the partition can be efficiently accelerated to quickly expand the working chamber volume, thereby improving the cavity expansion response speed of the cylinder structure under the liquid hammer phenomenon, and achieving the purpose of reducing the negative impact of the liquid hammer phenomenon on the compressor cylinder structure.

[0011] Specifically, the maximum pressure that the piston ring assembly can reach when moving within the working chamber and compressing wellhead natural gas is related to the clearance within the working chamber (the clearance itself also directly participates in protecting against liquid hammer damage as it serves as a storage space for liquid water). However, due to the unstable composition of wellhead natural gas, if liquid water directly enters the cylinder structure and / or the volume of liquid water generated during the compression process exceeds the inherent buffering capacity of the clearance within the cylinder structure, the liquid water will fill too much space in the working chamber, causing severe liquid hammer, which may directly damage the cylinder structure or affect the service life of related parts.

[0012] In this solution, a partition is used to divide the piston chamber into a working chamber and a buffer chamber. At the same time, a piston ring assembly is arranged in the working chamber. In this way, when the cylinder structure normally compresses wellhead natural gas, the working chamber is the compression chamber, and the partition forms the pressure boundary of the compression chamber. When there is no liquid water or only a small amount of liquid water in the working chamber, the clearance of the lower working chamber will not cause the pressure in the working chamber to rise sharply to a higher pressure. In this state, the cylinder structure can operate normally, that is, liquid hammer will not occur. However, when there is liquid water occupying a larger volume of the working chamber during the gas compression process, the liquid water makes the working chamber The effective clearance becomes smaller. During this process, the pressure in the working chamber will rise sharply to a higher pressure, and the volume of liquid water is proportional to the pressure increase value and the maximum pressure value. In this solution, on the one hand, the partition is configured to be able to break the fixed relationship in the piston chamber under the corresponding pressure difference, and the partition can move toward the side of the buffer chamber under this pressure difference. In this way, when the presence of liquid water in the piston chamber causes the pressure in the working chamber to rise sharply to a higher pressure and the pressure difference exceeds the set threshold (the set threshold value needs to be set according to the compressor efficiency, exhaust pressure, etc., and can be set to 0 for wellhead natural gas compressors).When the pressure in the working chamber is between 5 MPa and 2 MPa), the partition is broken by its original fixed relationship and moves toward the buffer chamber, so that the volume of the working chamber can expand rapidly. This expansion of volume is equivalent to the expansion of the clearance of the working chamber relative to the fixed stroke range of the piston ring assembly. That is, after the original fixed state of the partition is broken, the pressure in the working chamber continues to increase and is curbed. In other words, this solution provides a technical solution for reducing the maximum pressure in the cylinder when liquid hammer occurs by expanding the clearance volume of the cylinder body. On the other hand, to ensure the working efficiency of the compressor, the compressor needs to have a stable compression chamber boundary during normal operation. This solution is configured to also include a connecting channel to achieve: when the pressure in the compression chamber increases, the pressure in the buffer chamber can lag behind the increase in the pressure in the compression chamber. This solution uses the pressure balancing effect of the connecting channel to reduce the pressure difference on both sides of the partition and maintain the necessary pressure boundary of the working chamber at the expense of some compression efficiency. In this way, from the perspective of the partition's pressure resistance requirements, the partition can be made thinner by reducing the pressure difference (for example, when the connecting channel is not provided, the partition that meets the fatigue and pressure resistance requirements needs to be made of steel plates of more than 20 mm. When the connecting channel is used to reduce the pressure difference, the partition can be made thinner). After the pressure difference on both sides of the small partition, the partition that meets the fatigue and pressure resistance requirements only needs to use 5mm steel plate). When the liquid water volume in the working chamber is large, liquid hammer occurs and the pressure in the working chamber rises sharply (depending on the movement speed of the piston and the volume of liquid water in the compression chamber, the pressure in the compression chamber can rise several times the normal pressure growth rate. The throttling effect of the connecting channel causes the pressure difference on both sides of the partition to rise sharply. This throttling effect is also used to enable the cylinder structure to maintain appropriate compression efficiency). When the pressure difference reaches the set threshold and causes the fixed relationship After being destroyed, the thinner diaphragm, due to its lower mechanical inertia, can move faster toward the buffer chamber under this pressure differential, thereby expanding the clearance volume. Compared to the existing technology, which relies on the opening of the exhaust valve and the pressure relief channel, the response is affected by mechanical inertia and lags behind the increase in pressure in the compression chamber. The cylinder structure is damaged by liquid hammer before the corresponding valve plate is fully opened. This solution effectively optimizes the response speed of the clearance volume expansion process, reduces the maximum pressure in the piston chamber of the cylinder structure when liquid hammer occurs, and provides better protection for the cylinder structure against liquid hammer.

[0013] At the same time, as a technician in this field, when the fixed relationship of the partition in the piston chamber is destroyed, the original clearance of the working chamber is destroyed, and the original buffer chamber forms an abnormal clearance of the working chamber. In order to ensure the exhaust pressure and efficiency of the compressor, the compressor needs to be shut down for repair. Specifically, the partition is replaced / the setting of the partition in the piston chamber is restored and the compressor is restarted. Although this process will also cause compressor failure and necessary downtime, compared with the liquid hammer phenomenon that causes the cylinder structure to be directly damaged or the life is reduced, this solution can effectively shorten the use cost of the compressor and shorten the downtime (this solution only needs to restore the partition during repair, and it is not easy to cause multiple parts to be damaged by liquid hammer due to overhaul).

[0014] A further technical solution of the anti-liquid hammer compressor cylinder structure is:

[0015] A fixing ring is provided on the outer periphery of the partition, and the fixing ring is an annular structure coaxial with the partition. A second sealing ring is provided on the outer side of the fixing ring, and the second sealing ring is used to achieve axial sealing of the gap between the fixing ring and the wall of the piston cavity;

[0016] It also includes an end plate fixed to the end of the cylinder, and the fixing ring is connected to the end plate through an adjusting mechanism, and the adjusting mechanism is used to adjust the position of the fixing ring on the axis of the piston chamber.

[0017] The above scheme aims to provide a specific form of fixing the partition in the piston chamber. Specifically, the fixing ring serves as the outer ring of the outer periphery of the partition, the partition is fixed on the fixing ring, and the fixing ring is connected to the end plate through an adjusting mechanism, that is, a technical scheme is provided in which the partition is connected to the adjusting mechanism through a fixing ring, and the specific connection position is located on the end plate. In the above structural setting, the characteristics that the fixing ring can be processed to be thicker than the partition and each position of the outer periphery of the partition is connected to the fixing ring are utilized to strengthen the ability of the partition to resist uneven deformation of each position in the circumferential direction during the operation of the cylinder structure, so as to ensure the compression efficiency of the cylinder structure and the stability of the clearance; at the same time, this scheme is based on the fixing ring to complete the partition The connection of the plate in the piston cavity does not require changing the existing cylinder forming process for the processing scheme that usually uses castings as cylinder blanks; the above second sealing ring serves as an axial sealing structure, and the connectivity between the working chamber and the piston chamber is only affected by the connecting channel. Therefore, this scheme can effectively control the connectivity to ensure the compression efficiency and exhaust pressure of the compressor; the adjustment structure is used to adjust the position of the fixed ring on the axis of the piston cavity. When the position of the fixed ring changes, the position of the partition changes synchronously. Therefore, the above scheme of using partitions and connecting channels to achieve liquid hammer protection of the compressor cylinder can still reasonably adjust the clearance of the working chamber according to the production and compression medium characteristics. Preferably, the fixing relationship is destroyed by destroying the connection relationship between the fixing ring and the partition. The specific solution may be: under the pressure difference, the partition is deformed and comes out of the ring groove of the fixing ring, the ring weld between the partition and the fixing ring is destroyed, etc. With this solution, when restoring the state of the partition in the piston cavity, it is only necessary to complete the reconnection of the fixing ring and the partition, and constrain the partition to a suitable position in the piston cavity through the adjustment mechanism. In this solution, the destruction of the original fixing relationship of the partition and the restoration of the installation of the partition on the cylinder structure will not affect the main structure of the cylinder structure, and has the purpose of reducing the use and maintenance cost of the cylinder structure.

[0018] The adjustment mechanism includes a plurality of adjustment screws, the adjustment screws being evenly distributed in an annular pattern relative to the axis of the fixing ring, each adjustment screw passing through the fixing ring and the end plate, the adjustment screws being threadedly connected to the end plate, and the adjustment screws passing through the fixing ring through a through hole provided on the fixing ring, the adjustment screws being in clearance fit with the through hole;

[0019] Each adjusting screw is provided with a clamping ring for limiting the position of the fixing ring in the axial direction of the adjusting screw.

[0020] The above provides a specific implementation method of the adjustment mechanism, in which the clearance fit is used to enable the adjustment screw to rotate independently of the fixed ring in the through hole. By rotating the adjustment screw, the connecting thread between the adjustment screw and the end plate is used to adjust the position of the adjustment screw in the direction of its axis. The fixed ring moves synchronously with the adjustment screw under the action of the retaining ring, thereby achieving the purpose of adjusting the position of the partition in the piston chamber. The use of multiple adjustment screws and uniform arrangement around the axis of the retaining ring is intended to uniformly support the various positions of the retaining ring in the circumferential direction, so as to avoid axial leakage of the second sealing ring due to uneven circumferential pressure when the pressure on both sides of the partition fluctuates. In specific implementation, the adjustment screw can be processed to have a boss as the retaining ring on itself, or the retaining ring can be set as a shaft elastic retaining ring installed on the adjustment screw through an annular groove.

[0021] Each adjusting screw is equipped with a spring tube, which is sleeved on the outside of the adjusting screw. One end of the spring tube is supported on the fixing ring, and the other end is supported on the inner wall of the end plate.

[0022] The utility model also includes a locking nut which is threadedly connected to the adjusting screw and is used for abutting against the outer wall of the end plate.

[0023] In the above scheme, when the position of the fixed ring is constrained by the adjusting screw, the spring tube is in a compressed state, and the outer wall of the adjusting screw is in contact with the inside of the spring tube to constrain the spring tube in a stable position. The spring tube is used to achieve: when the position of the partition in the piston cavity is adjusted by rotating the adjusting screw, the spring tube provides thrust for the fixed ring through elastic deformation. Under such application, on the one hand, when the adjusting screws cannot be adjusted synchronously, the rotational resistance of a single adjusting screw becomes larger under the joint positive influence of the spring tube and the second sealing ring. When a torque wrench is used to rotate each adjusting screw separately, the influence of the above spring tube on the rotational resistance The compression amount of the second sealing ring on the side where the adjusting screw is located can be reduced. Such application can not only protect the second sealing ring, but also help maintain the coaxiality of the partition and the piston chamber. On the other hand, the fixed ring can be pushed to fit with the clamping ring close to the working chamber under the thrust of each spring tube. In such application, not only can the spring tube be used to constrain the fixed ring to a relatively stable axial position of the adjusting screw, but also the fluctuation of the assembly formed by the fixed ring and the partition under the pressure difference on both sides can be reduced to optimize the working stability of the compressor. At the same time, the gap size in the clearance fit can be set slightly larger to improve the convenience of adjusting the position of the partition in the piston chamber.

[0024] The inner wall of the fixing ring is provided with an annular groove coaxial with the fixing ring, the edge of the partition is embedded in the annular groove, and a ring weld is also provided on the side of the partition close to the working chamber. The ring weld realizes the welding connection between the partition and the fixing ring and the sealing of the gap between the partition and the fixing ring.

[0025] In the above scheme, the annular groove is used to clamp the partition plate to the inner side of the retaining ring. The front and rear sidewalls of the annular groove respectively constrain the front and rear sides of the partition plate, maintaining the partition plate's fixed stability during non-liquid hammer operation. The annular weld is used to seal the corresponding gap to prevent the connectivity between the working chamber and the buffer chamber from being disrupted by channels outside the communication channel. The annular weld is located on the side of the partition plate closest to the working chamber to ensure that, when liquid hammer occurs, the annular weld is broken under tensile force, allowing the partition plate to escape from the annular groove, thereby breaking the fixed relationship. In a specific implementation, the retaining ring, partition plate, and annular weld are preferably all made of stainless steel. In this application, when the annular weld connection is broken under a pressure differential, the amount of debris generated and entering the working chamber due to the breakage can be effectively reduced, thereby reducing the risk of scratches on the inner wall of the piston chamber and the piston ring assembly caused by this debris before the piston ring assembly stops moving. Since the response speed of the above clearance volume expansion process is affected by the weight of the partition, and the partition also needs to have an appropriate thickness to match the requirements of its pressure resistance and stability, a better application is: setting the partition to a stainless steel plate and a substrate laminated structure, and the side of the partition close to the working chamber is a stainless steel plate, and the side of the partition away from the working chamber is a non-stainless steel plate and a metal plate substrate, the fixing ring is a stainless steel ring, and the girth weld is welded with stainless steel. In such an application, after the girth weld is destroyed under the pressure difference, it not only has the effect of reducing the amount of debris generated, but also, compared with setting the partition The entire structure is configured as a stainless steel plate. On the basis of having the same compressive strength and stability characteristics, the above laminated structure has a smaller mass (taking a substrate of 45 carbon steel plate, cast steel plate, ductile iron plate, and a stainless steel plate of 304 / 316 austenitic stainless steel plate as an example, in order to withstand the same pressure difference and maintain stability under alternating pressure difference, the stainless steel partition needs to be designed to be thicker, and its material density is also slightly higher than that of the substrate, so the final weight will be greater than that of the laminated structure partition). Therefore, while reducing debris, this application can reduce the overall mechanical inertia of the partition to facilitate the response speed.

[0026] In a specific application, the side of the annular groove close to the buffer chamber is provided with a guide groove of a frustum structure, and the end of the frustum structure with a larger diameter is close to the working chamber. In this way, when the middle part of the partition is recessed to a certain extent under the pressure difference on both sides, the supporting capacity of the back side of the annular groove on the partition is weakened, so that the partition can be more smoothly removed from the annular groove.

[0027] The communication channel is a communication groove provided on the wall of the piston cavity, and the communication groove is a strip-shaped groove on the cavity wall, one end of the communication groove is located in the working cavity, and the other end of the communication groove is located in the buffer cavity;

[0028] There are multiple communicating grooves, which are arranged at intervals in the circumferential direction of the piston cavity.

[0029] The above provides a specific form of connecting channel setting: a connecting groove set on the wall of the piston chamber and across the partition is used as the connecting channel. Such a connecting channel can be obtained by surface processing the wall of the piston chamber, which not only has high processing efficiency, but also has the characteristics of high connecting channel processing precision; the connecting grooves are set as multiple and arranged at intervals in the circumferential direction of the piston chamber to achieve: relative to the partition, the connecting grooves form multiple connecting channels in the circumferential direction of the partition. In this way, compared with the use of a single connecting groove (a single connecting groove has the same fluid conductivity as the multiple connecting grooves used in this scheme), in the process of establishing a pressure difference, the more balanced airflow in the circumferential direction of the partition can not only reduce the impact of the airflow on the vibration of the partition, but also, this method is beneficial to establishing pressure balance at various positions in the working chamber (mainly the compressor suction process) and the buffer chamber (mainly the compressor compression process).

[0030] The communication channel is a communication hole provided on the side wall of the piston chamber, one end of the communication hole is communicated with the exhaust hole of the cylinder, and the other end of the communication hole is communicated with the buffer chamber;

[0031] It also includes an adjusting cone arranged in the communicating hole, and the adjusting cone is used to adjust the fluid conductivity of the communicating hole.

[0032] The above scheme provides another form of connecting channel setting, specifically: the connecting hole realizes the connection between the working chamber and the buffer chamber through the orifices at both ends thereof, and is set to also include an adjusting cone to solve the problem that the connecting groove cannot adjust the connecting capacity between the working chamber and the buffer chamber. As mentioned above, this scheme uses baffles and buffer chambers to achieve the anti-liquid hammer effect while sacrificing the efficiency of the compressor. For well flow discharge stages such as those with no liquid water, low liquid water content or low water vapor content, the possibility of liquid hammer in the compressor is low. In such cases, it is not easy for the fixed relationship of the baffle to be destroyed. Therefore, it can be set to reduce the fluid conductivity of the connecting hole through the adjusting cone (the pressure difference between the two sides of the baffle is established faster under such application, and the smaller liquid content in the working chamber can trigger the destruction of the fixed relationship), so as to reduce the loss of gas in the pressurization stage of the cylinder structure and the amount of gas injected into the working chamber from the buffer chamber during the suction stage, so as to achieve the purpose of optimizing the efficiency of the compressor; for well flow discharge stages such as those with no liquid water, low liquid water content or low water vapor content, the possibility of liquid hammer in the compressor is low. In such cases, it is not easy for the fixed relationship of the baffle to be destroyed. Therefore, it can be set to reduce the fluid conductivity of the connecting hole through the adjusting cone (in such a case, the pressure difference between the two sides of the baffle is established faster, and the fixed relationship can be triggered to be destroyed by a smaller amount of liquid in the working chamber), so as to reduce the gas loss in the pressurization stage of the cylinder structure and the amount of gas injected into the working chamber from the buffer chamber during the suction stage, so as to achieve the purpose of optimizing the efficiency of the compressor; for well flow discharge stages such as those with liquid water, low liquid water content or low water vapor content, the possibility of liquid hammer in the compressor is low. In such cases, it is not easy for the fixed relationship of the baffle to be destroyed, so it can be set to reduce the pressure loss of the connecting hole through the adjusting cone (in such a case, the pressure difference between During the discharge phase of well fluids with high water or water vapor content, the compressor is more likely to experience liquid hammer. In such situations, if the flow rate of the connecting hole is low, the diaphragm's fixed relationship is more likely to be broken, triggering the liquid hammer protection. Therefore, the adjusting cone can be used to increase the flow rate of the connecting hole (this operation slows down the pressure differential across the diaphragm, requiring a higher amount of liquid in the working chamber to trigger the breaking of the fixed relationship). This method reduces compressor efficiency and discharge pressure, enhances the cylinder structure's adaptability to liquid levels in the working chamber (the working chamber will have a higher liquid content when liquid hammer occurs), and reduces the equipment failure rate caused by the breaking of the fixed relationship. Those skilled in the art will know that the adjusting cone can adopt a needle valve stem structure, and the flow rate of the connecting hole can be adjusted by adjusting the insertion depth of the adjusting cone in the connecting hole. The purpose of setting the orifice on one side of the connecting hole on the exhaust hole is to achieve: according to the relative positions of the working chamber and the buffer chamber, the connecting hole should be set as a bent hole, so the processing of the connecting hole should adopt a scheme of first setting multiple intersecting process holes, and then partially blocking some of the process holes to form a connecting hole. When a structure is adopted in which the process hole is connected to the hole wall at the inlet position of the exhaust hole (it is necessary to avoid the exhaust valve installed in the exhaust hole and in any open or closed state affecting the connection between the exhaust hole and the working chamber), based on the basic configuration of the cylinder body structure in which the air inlet hole and the exhaust hole are generally set on the side of the cylinder, the process hole can be set to have a horizontal hole parallel to the axis of the cylinder and a vertical hole along the radial direction of the cylinder. The horizontal hole intersects with the vertical hole, and the outer orifices of the horizontal hole and the vertical hole are blocked by plugs respectively to complete the forming of the connecting hole.

[0033] Also included is a pressure sensor mounted on the cylinder, the pressure sensor being used to monitor the pressure in the working chamber;

[0034] Also included is a position sensor for monitoring the position of the piston ring assembly in the cylinder barrel;

[0035] It also includes a pressure relief hole provided on the cylinder barrel, wherein the pressure relief hole is provided with an electromagnetic pressure relief valve for controlling the on-off of the pressure relief hole;

[0036] The system further includes a control module, wherein the control module is signal-connected to the pressure sensor, the position sensor, and the electromagnetic pressure relief valve. The signal connection is as follows: the control module receives detection results of the pressure sensor and the position sensor, and transmits an action control signal to the electromagnetic pressure relief valve;

[0037] The control module is configured to: determine whether the pressure of the current working chamber exceeds the limit based on the monitoring values ​​of the position sensor and the monitoring values ​​of the pressure sensor, and when the judgment result is that the pressure exceeds the limit, trigger the transmission of an action control signal to the electromagnetic pressure relief valve to open the electromagnetic pressure relief valve.

[0038] As described above, when the anti-liquid shock protection is triggered by the partition and the buffer chamber, the original position of the partition in the piston chamber is destroyed. At this time, the compression efficiency and exhaust pressure of the compressor are greatly affected. It is necessary to enable the compressor again after restoring the partition. As a pre-protection for the partition triggering the anti-liquid shock protection, the above provides an electronically controlled pre-protection scheme. Specifically, the scheme utilizes the characteristics of the position of the piston ring assembly in the cylinder to associate with the gas compression ratio in the working chamber, and utilizes the comparison result of the pressure associated with the pressure monitoring value and the position monitoring value to determine whether to trigger the electromagnetic pressure relief valve to open. For example, when the working chamber occupies the remaining gap due to liquid water, resulting in a significant increase in the internal pressure growth rate of the working chamber of the piston ring assembly during the compression stroke, it can be determined that the internal pressure of the working chamber at the current position of the piston ring assembly exceeds the limit, thereby triggering the electromagnetic pressure relief valve to open to discharge the internal pressure of the working chamber, thereby achieving the purpose of the pre-protection to reduce the probability of the partition triggering the anti-liquid shock protection.

[0039] It is easy to understand that the above electronic control scheme and partition scheme are parallel schemes for realizing anti-liquid hammer protection. The electronic control scheme as the front-stage protection aims to achieve: in the existing technology, the piston ring assembly requires less time to complete a cycle of movement, and the cylinder has the characteristic of temperature instability. This requires the relevant sensors to complete a signal detection, which not only requires a short time and a high signal pickup frequency, but also has the characteristic that the detection accuracy is less affected by temperature. When high-precision, high-dynamic performance sensors and temperature compensation schemes are adopted, the impact of detection delay links and detection accuracy on the response speed of liquid hammer protection can be effectively guaranteed. However, the cost of using sensors is very high, which is not conducive to the economic efficiency of compressor use. Therefore, on this basis, further adopting the partition scheme as the back-stage protection can effectively reduce the system requirements for the above electronic control scheme to reduce the setting cost of the electronic control scheme, and achieve effective anti-liquid hammer protection and take into account economy under the joint action of the above two levels of protection.

[0040] In specific implementation, the preferred position sensor is a magnetostrictive displacement sensor of general accuracy, and the pressure sensor is a sensor based on piezoelectric crystals and metal diaphragms. Such sensors have the characteristics of low result response delay, and the electromagnetic pressure relief valve also has the characteristics of rapid action response.

[0041] Regarding the control module, to reduce computational response delay, the specific logic of the control module may be: calculating the difference or rate of change between two adjacent pressure monitoring results, as well as the difference or rate of change between two adjacent position monitoring results, then dividing the differences or rates of change (the pressure detection result divided by the position detection result) to determine whether the current working chamber pressure exceeds the limit. This logic can be implemented in software or using an analog differential circuit (requiring signal type support: analog differential circuits are only suitable for processing analog signals). However, when selecting a specific solution, priority should be given to a solution that balances cost control and computational time.

[0042] The present solution also relates to an anti-liquid hammer compressor, comprising a compressor cylinder structure, wherein the compressor cylinder structure is the compressor cylinder structure provided by any one of the above items;

[0043] The piston ring assembly includes a ring body made of a metal plate, which is connected to the piston rod, and also includes a self-lubricating layer made of a polymer self-lubricating material. The self-lubricating layer is an annular structure and is sleeved on the outside of the ring body. It also includes a plurality of first sealing rings installed on the outer periphery of the self-lubricating layer. The first sealing rings are arranged in sequence in the axial direction of the piston ring assembly, and the first sealing rings serve as axial sealing rings between the piston ring assembly and the wall of the working chamber.

[0044] The above-mentioned anti-liquid hammer compressor is a compressor including the compressor cylinder structure. In summary, this solution has the characteristic of effectively optimizing the response speed of the clearance volume expansion process. Furthermore, in view of the sand-producing characteristics of the well fluid, in order to reduce the impact of the relevant abrasive particles in the fluid on the piston ring assembly and the piston cavity wall, a self-lubricating layer such as a polytetrafluoroethylene material is provided on the outer periphery of the ring body, and a first sealing ring is provided on the basis of the self-lubricating layer, aiming to achieve: utilizing the characteristic that abrasive particles can be embedded in the polytetrafluoroethylene self-lubricating polymer material, reducing the content of free abrasive particles in the piston cavity, and reducing the impact of the abrasive particles on the piston cavity wall.

[0045] This solution also relates to a wellhead natural gas compression method, which is implemented based on the compressor cylinder structure described in any one of the above, and comprises:

[0046] The piston ring assembly reciprocates in the working chamber to compress the natural gas at the wellhead;

[0047] During the process of the piston ring assembly compressing the wellhead natural gas, the connecting passage is used to connect the working chamber and the buffer chamber, thereby reducing the pressure difference on both sides of the partition plate;

[0048] When the pressure difference exceeds the set threshold, the fixed relationship of the diaphragm in the piston cavity is destroyed under the pressure difference on both sides of the diaphragm, and the diaphragm can move toward the side where the buffer cavity is located under the pressure difference;

[0049] The compressor cylinder adopts a single-cylinder single-stage compression method that compresses wellhead natural gas only when the piston ring assembly moves forward or backward, or adopts a single-cylinder two-stage compression method in which air inlet holes and exhaust holes are provided at both ends of the cylinder barrel, and the wellhead natural gas on one side of the piston ring assembly is compressed when the piston ring assembly moves forward or backward;

[0050] When the compressor cylinder adopts a single-cylinder single-stage compression mode, the partition is set on the side of the piston ring assembly away from the piston rod. The piston ring assembly compresses the wellhead natural gas when it moves toward the side where the partition is located. The channel opening of the communication channel set on the cylinder is located at the end of the working chamber close to the partition.

[0051] When the compressor cylinder adopts a single-cylinder two-stage compression method, the partition is arranged on the side of the piston ring assembly away from the piston rod, and the channel opening of the connecting channel arranged on the cylinder is located at the end of the working chamber close to the partition, and the working chamber is used as: the working chamber between the partition and the piston ring assembly is used as the first-stage compression chamber, and the working chamber on the side of the piston ring assembly away from the partition is used as the second-stage compression chamber. The second-stage compression chamber is used to re-pressurize the wellhead natural gas after the first-stage compression chamber is pressurized.

[0052] The above method is a method for realizing wellhead natural gas compression based on the compressor cylinder structure, and further explains the setting method of the partition under the specific compression mode of the compressor cylinder: the buffer chamber is located on the side of the piston ring assembly away from the piston rod, so that after the fixed relationship is destroyed, the conductivity between the formed working chamber and the buffer chamber is used to quickly prevent the internal pressure in the piston chamber from further increasing. Compared with setting the buffer chamber on the side of the cylinder or the end where the piston rod is located, the purpose of optimizing the response speed of the clearance volume expansion process is achieved. The selection of the position of the channel mouth of the above connecting channel enables the piston ring assembly to use the connecting channel to establish a continuously increasing pressure difference on both sides of the partition during the entire compression stroke.

[0053] The above scheme illustrates the relationship between the working chambers on both sides of the piston ring assembly at different stages of wellhead natural gas pressurization when the compressor cylinder adopts a single-cylinder two-stage compression method. It is intended to address the following problems: the medium processed by the secondary compression chamber is the medium discharged from the primary compression chamber, stored in the buffer tank, and separated from the water and gas. Therefore, the primary compression chamber is more susceptible to the water content of the well flow and liquid hammer occurs. In this context, a partition is provided to provide liquid hammer protection for the primary compression chamber. This pressurization method not only has the high compression efficiency of the single-cylinder two-stage compression method, but also uses the partition to provide high-response liquid hammer protection for the wellhead natural gas, so that the wellhead natural gas compression not only has the characteristics of high compression efficiency, but also has the characteristics of reliable liquid hammer protection.

[0054] The present invention has the following beneficial effects:

[0055] This solution is configured so that the fixed relationship of the partition in the piston chamber can be destroyed under a corresponding pressure differential, and the partition can move toward the side where the buffer chamber is located under this pressure differential. In this way, after the original fixed state of the partition is destroyed, the pressure in the working chamber is curbed from continuing to increase. In other words, this solution provides a technical solution for reducing the maximum pressure in the cylinder when liquid hammer occurs by increasing the clearance volume of the cylinder body.

[0056] By further including a connecting channel, the present solution can achieve the following: utilizing the pressure balancing effect of the connecting channel to reduce the pressure difference on both sides of the partition and maintain the necessary pressure boundary of the working chamber. In this way, from the perspective of the partition's pressure resistance requirement, the partition can be made thinner by reducing the pressure difference. When liquid hammer occurs due to the large volume of liquid water in the working chamber, causing a sharp increase in the pressure in the working chamber, when the fixed relationship is destroyed, the thinner partition, due to its lower mechanical inertia, moves toward the side where the buffer chamber is located at a faster speed and rapidly expands the clearance volume. This solution can effectively optimize the response speed of the clearance volume expansion process, reduce the maximum pressure of the piston chamber in the cylinder structure when liquid hammer occurs, and better provide anti-liquid hammer protection for the cylinder structure.

[0057] This solution only requires replacing the partition / restoring the setting of the partition in the piston chamber after the fixed relationship is destroyed. Compared with the liquid hammer phenomenon that causes the cylinder structure to be directly destroyed or the service life to be reduced, this solution can effectively shorten the use cost of the compressor and shorten the downtime. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] Figure 1 This is a cross-sectional view of a specific embodiment of the liquid-surge-proof compressor cylinder structure described in this solution;

[0059] Figure 2 for Figure 1 A partial enlarged view of part A;

[0060] Figure 3 For Figure 2 A structural diagram of a specific embodiment in which the communicating channel is formed by using communicating holes based on the structure shown.

[0061] The reference numerals in the accompanying drawings are: 1, air inlet, 2, piston chamber, 3, piston ring assembly, 4, cylinder, 5, partition, 6, connecting groove, 7, buffer chamber, 8, exhaust hole, 9, ring body, 10, self-lubricating layer,

[0062] 11. First sealing ring, 12. Snap ring, 13. Fixed ring, 14. Ring groove, 15. Second sealing ring, 16. Adjusting screw, 17. Spring tube, 18. Connecting hole, 19. Adjusting cone, 20. Pressure sensor, 21. End plate, 22. Pressure relief hole. DETAILED DESCRIPTION

[0063] The present invention will be further described in detail below with reference to the embodiments, but the present invention is not limited to the following embodiments:

[0064] Example 1:

[0065] like Figures 1 to 3 As shown, the anti-liquid-surge compressor cylinder structure includes a cylinder barrel 4 and a piston ring assembly 3. The cylinder barrel 4 is provided with a piston chamber 2 and further includes a partition plate 5 fixed inside the piston chamber 2. In the axial direction of the piston chamber 2, the partition plate 5 separates the piston chamber 2 into a working chamber and a buffer chamber 7. The piston ring assembly 3 is disposed in the working chamber. The structure also includes a communication channel provided on the cylinder barrel 4 and / or the partition plate 5. The communication channel is used to achieve mutual communication between the working chamber and the buffer chamber 7 on both sides of the partition plate 5.

[0066] The partition 5 is configured such that when the pressure difference between the working chamber pressure and the buffer chamber 7 pressure exceeds a set threshold, the fixed relationship of the partition 5 in the piston chamber 2 is destroyed under the pressure difference on both sides of the partition 5, and the partition 5 can move toward the side where the buffer chamber 7 is located under the pressure difference.

[0067] This solution is intended to address the following issues: For liquid water that has entered the compression chamber of the compressor (i.e., the working chamber mentioned above) or liquid water formed in the compression chamber, the existing method of using the internal pressure in the compression chamber to push open the pressure relief channel requires overcoming the mechanical inertia of the valve core, spring, etc. During the process of continuous pressure increase in the compression chamber, the pressure relief channel is not opened in time due to the above mechanical inertia. Especially when the liquid water occupies a large volume in the compression chamber, the rapidly increasing internal pressure in the compression chamber will still cause severe liquid hammer in the cylinder structure, resulting in direct damage to compressor parts or accelerated part fatigue. The high failure rate of the compressor cylinder structure seriously affects the orderly and efficient production of wellhead natural gas.

[0068] This solution utilizes the communication effect generated by the communication channel to reduce the pressure difference between the working chamber and the buffer chamber 7 on both sides of the partition 5, so as to use the thinner partition 5 to form the working chamber pressure boundary. When liquid hammer occurs in the working chamber, the thinner partition 5 has the characteristic of smaller mechanical inertia, so that when the partition 5 moves toward the buffer chamber 7 to expand the working chamber volume, the partition 5 can be efficiently accelerated to quickly expand the working chamber volume, thereby improving the cavity expansion response speed of the cylinder structure under the liquid hammer phenomenon, and achieving the purpose of reducing the negative impact of the liquid hammer phenomenon on the compressor cylinder structure.

[0069] Specifically, the maximum pressure that the piston ring assembly 3 can reach when moving in the working chamber and compressing wellhead natural gas is related to the clearance of the working chamber (the clearance itself also directly participates in the protection against liquid hammer damage as a storage space for liquid water). However, due to the unstable composition of wellhead natural gas, if the volume of liquid water directly entering the cylinder structure and / or the liquid water generated during the compression process exceeds the inherent buffering capacity of the clearance within the cylinder structure, the liquid water will fill too much space in the working chamber, causing severe liquid hammer, which will directly damage the cylinder structure or shorten the service life of related parts.

[0070] In this solution, the piston chamber 2 is divided into a working chamber and a buffer chamber 7 by using a partition 5. At the same time, the piston ring assembly 3 is arranged in the working chamber. In this way, when the cylinder structure normally compresses the wellhead natural gas, the working chamber is the compression chamber, and the partition 5 forms the pressure boundary of the compression chamber. When there is no liquid water or only a small amount of liquid water in the working chamber, the clearance of the lower working chamber will not cause the pressure in the working chamber to rise sharply to a higher pressure. In this state, the cylinder structure can operate normally, that is, liquid hammer will not occur. However, when there is liquid water occupying a larger volume of the working chamber during the gas compression process, the liquid water makes the working chamber The effective clearance becomes smaller. During this process, the pressure in the working chamber will rise sharply to a higher pressure, and the volume of liquid water is proportional to the pressure increase value and the maximum pressure value. In this solution, on the one hand, the partition 5 is configured so that its fixed relationship in the piston chamber 2 can be destroyed under the corresponding pressure difference, and the partition 5 can move toward the side where the buffer chamber 7 is located under this pressure difference. In this way, when the presence of liquid water in the piston chamber 2 causes the pressure in the working chamber to rise sharply to a higher pressure and the pressure difference exceeds the set threshold (the set threshold value needs to be set according to the compressor efficiency, exhaust pressure, etc., and can be set to 0 for wellhead natural gas compressors).When the pressure is between 5Mpa and 2Mpa), the partition 5 is broken through the original fixed relationship and moves to the buffer chamber 7 side, so that the volume of the working chamber can be rapidly expanded. The expansion of this volume is equivalent to the expansion of the clearance of the working chamber relative to the fixed stroke range of the piston ring assembly 3. That is, after the original fixed state of the partition 5 is broken, the pressure of the working chamber is curbed from continuing to increase. That is, this solution provides a technical solution to reduce the maximum pressure in the cylinder when the liquid hammer phenomenon occurs by expanding the clearance volume of the cylinder body; on the other hand, in order to ensure the working efficiency of the compressor, the compressor needs to have a stable compression when it is working normally. The cavity boundary, this solution is set to also include a connecting channel, which is used to achieve: when the compression cavity pressure increases, the pressure in the buffer cavity 7 can lag behind the increase in the compression cavity pressure. This solution uses the pressure balancing effect of the connecting channel to reduce the pressure difference on both sides of the partition 5 and maintain the necessary pressure boundary of the working cavity by sacrificing part of the compression efficiency. In this way, from the perspective of the pressure resistance requirement of the partition 5, the partition 5 can be set thinner by reducing the pressure difference (for example, when the connecting channel is not set, the partition 5 that meets the fatigue and pressure resistance requirements needs to be made of steel plates of more than 20 mm. When the connecting channel is used After reducing the pressure difference on both sides of the partition 5, the partition 5 that meets the fatigue and pressure resistance requirements only needs to use a 5mm steel plate). When the liquid water volume in the working chamber is large, causing liquid hammer and causing the working chamber pressure to rise sharply (depending on the movement speed of the piston and the volume of liquid water in the compression chamber, the pressure in the compression chamber can rise several times the normal pressure growth rate, and the throttling effect of the connecting channel causes the pressure difference on both sides of the partition 5 to rise sharply. This throttling effect is also used to enable the cylinder structure to maintain appropriate compression efficiency). When the pressure difference reaches the set threshold and causes the fixed relationship After being destroyed, the thinner diaphragm 5, due to its lower mechanical inertia, can move faster toward the buffer chamber 7 under this pressure differential, thereby expanding the clearance volume. Compared to the existing technology, which relies on the opening of the exhaust valve and the pressure relief channel, the response is affected by mechanical inertia and lags behind the increase in compression chamber pressure. Before the corresponding valve plate is fully opened, the cylinder structure will be damaged by liquid hammer. This solution can effectively optimize the response speed of the clearance volume expansion process, reduce the maximum pressure in the piston chamber 2 of the cylinder structure when liquid hammer occurs, and better protect the cylinder structure from liquid hammer.

[0071] At the same time, as a person skilled in the art, when the fixed relationship of the partition 5 in the piston chamber 2 is destroyed, the original clearance of the working chamber is destroyed, and the original buffer chamber 7 forms an abnormal clearance of the working chamber. In order to ensure the exhaust pressure and efficiency of the compressor, the compressor needs to be shut down for repair. Specifically, the partition 5 is replaced / the setting of the partition 5 in the piston chamber 2 is restored and then the compressor is restarted. Although this process will also cause compressor failure and necessary downtime, compared with the liquid hammer phenomenon that causes the cylinder structure to be directly damaged or the life is reduced, this solution can effectively shorten the use cost of the compressor and shorten the downtime (this solution only needs to restore the partition 5 during repair, and it is not easy to cause multiple parts to be overhauled due to liquid hammer damage).

[0072] Example 2:

[0073] This embodiment is further refined based on the embodiment 1:

[0074] A fixing ring 13 is provided on the outer periphery of the partition 5. The fixing ring 13 is an annular structure coaxial with the partition 5. A second sealing ring 15 is provided on the outer side of the fixing ring 13. The second sealing ring 15 is used to achieve axial sealing of the gap between the fixing ring 13 and the wall of the piston chamber 2;

[0075] It also includes an end plate 21 fixed to the end of the cylinder 4 , and the fixing ring 13 is connected to the end plate 21 through an adjusting mechanism, and the adjusting mechanism is used to adjust the position of the fixing ring 13 on the axis of the piston chamber 2 .

[0076] The above scheme is intended to provide a specific form of fixing the partition 5 in the piston chamber 2. Specifically, the fixing ring 13 serves as the outer ring of the outer periphery of the partition 5. The partition 5 is fixed on the fixing ring 13. The fixing ring 13 is connected to the end plate 21 through an adjusting mechanism. That is, a technical scheme is provided in which the partition 5 is connected to the adjusting mechanism through the fixing ring 13, and the specific connection position is located on the end plate 21. In the above structural setting, the fixing ring 13 can be processed to be thicker than the partition 5 and each position of the outer periphery of the partition 5 is connected to the fixing ring 13. The ability of the partition 5 to resist uneven deformation of each position in the circumferential direction during the operation of the cylinder structure is strengthened to ensure the compression efficiency of the cylinder structure and the stability of the clearance. At the same time, this scheme is based on the fixed The ring 13 completes the connection of the partition 5 in the piston chamber 2. For the processing scheme that usually uses castings as the cylinder 4 blank, there is no need to change the existing cylinder 4 molding process; the above second sealing ring 15 serves as an axial sealing structure, and the connectivity between the working chamber and the piston chamber 2 is only affected by the connecting channel. Therefore, this scheme can effectively control the connectivity to ensure the compression efficiency and exhaust pressure of the compressor; the adjustment structure is used to adjust the position of the fixed ring 13 on the axis of the piston chamber 2. When the position of the fixed ring 13 changes, the position of the partition 5 changes synchronously. Therefore, the above scheme of using the partition 5 and the connecting channel to achieve liquid hammer protection of the compressor cylinder can still reasonably adjust the clearance of the working chamber according to the production and compression medium characteristics. Preferably, the fixing relationship is destroyed by destroying the connection relationship between the fixing ring 13 and the partition 5. The specific solution may be: under the pressure difference, the partition 5 is deformed and comes out of the ring groove 14 of the fixing ring 13, the ring weld between the partition 5 and the fixing ring 13 is destroyed, etc. With this solution, when restoring the state of the partition 5 in the piston chamber 2, it is only necessary to complete the reconnection of the fixing ring 13 and the partition 5, and constrain the partition 5 to a suitable position in the piston chamber 2 through the adjustment mechanism. In this solution, the destruction of the original fixing relationship of the partition 5 and the restoration of the installation of the partition 5 on the cylinder structure will not affect the main structure of the cylinder structure, and has the purpose of reducing the use and maintenance cost of the cylinder structure.

[0077] Furthermore, the adjustment mechanism includes a plurality of adjustment screws 16, which are uniformly distributed in an annular shape relative to the axis of the fixing ring 13. Each adjustment screw 16 passes through the fixing ring 13 and the end plate 21. The adjustment screw 16 is threadedly connected to the end plate 21. The adjustment screw 16 passes through the fixing ring 13 through a through hole provided on the fixing ring 13, and the adjustment screw 16 is clearance-matched with the through hole.

[0078] Each adjusting screw 16 is provided with a snap ring 12 for limiting the position of the fixing ring 13 in the axial direction of the adjusting screw 16 .

[0079] The above provides a specific implementation of the adjustment mechanism, in which the clearance fit is used to enable the adjusting screw 16 to rotate in the through hole independently of the fixing ring 13. By rotating the adjusting screw 16, the connecting thread between the adjusting screw 16 and the end plate 21 is used to adjust the position of the adjusting screw 16 in the axial direction. The fixing ring 13 moves synchronously with the adjusting screw 16 under the action of the retaining ring 12, thereby achieving the purpose of adjusting the position of the partition 5 in the piston chamber 2. The use of multiple adjusting screws 16 and the uniform arrangement around the axis of the fixing ring 13 is intended to uniformly support the various positions of the fixing ring 13 in the circumferential direction to avoid axial leakage of the second sealing ring 15 due to uneven circumferential pressure when the pressure on both sides of the partition 5 fluctuates. In specific implementation, the adjusting screw 16 can be processed to have a boss on itself that serves as the retaining ring 12, or the retaining ring 12 can be set as a shaft elastic ring installed on the adjusting screw 16 through an annular groove.

[0080] Furthermore, each adjusting screw 16 is equipped with a spring tube 17, which is sleeved on the outside of the adjusting screw 16. One end of the spring tube 17 is supported on the fixing ring 13, and the other end is supported on the inner wall of the end plate 21.

[0081] It also includes a locking nut that is threadedly connected to the adjusting screw 16 and is used to abut against the outer wall of the end plate 21.

[0082] In the above scheme, when the position of the fixing ring 13 is constrained by the adjusting screw 16, the spring tube 17 is in a compressed state, and the outer wall of the adjusting screw 16 is in contact with the inside of the spring tube 17 to constrain the spring tube 17 in a stable position. The spring tube 17 is used to achieve: when the position of the partition 5 in the piston chamber 2 is adjusted by rotating the adjusting screw 16, the spring tube 17 provides thrust for the fixing ring 13 through elastic deformation. Under such application, on the one hand, when the adjusting screws 16 cannot be adjusted synchronously, the rotation resistance of the single adjusting screw 16 becomes larger under the joint positive influence of the spring tube 17 and the second sealing ring 15. When the torque wrench is used to rotate each adjusting screw 16 separately, the above spring tube 17 has no effect on the rotation The influence of resistance can reduce the compression amount of the second sealing ring 15 on the side where the adjusting screw 16 is located. Such application can not only protect the second sealing ring 15, but also help to maintain the coaxiality of the partition 5 and the piston chamber 2. On the other hand, the fixing ring 13 can be pushed to fit with the retaining ring 12 close to the working chamber under the thrust of each spring tube 17. In such application, not only can the spring tube 17 be used to constrain the fixing ring 13 to a relatively stable axial position of the adjusting screw 16, but also reduce the fluctuation of the assembly formed by the fixing ring 13 and the partition 5 under the pressure difference on both sides to optimize the working stability of the compressor. At the same time, the gap size in the clearance fit can be set slightly larger to improve the convenience of position adjustment of the partition 5 in the piston chamber 2.

[0083] Furthermore, the inner wall of the fixing ring 13 is provided with an annular groove 14 coaxial with the fixing ring 13, and the edge of the partition 5 is embedded in the annular groove 14. The side of the partition 5 close to the working chamber is also provided with an annular weld, and the annular weld realizes the welding connection between the partition 5 and the fixing ring 13 and the sealing of the gap between the partition 5 and the fixing ring 13.

[0084] In the above scheme, the annular groove 14 is used to clamp the partition 5 to the inner side of the retaining ring 13. The front and rear sidewalls of the annular groove 14 respectively constrain the front and rear sides of the partition 5, maintaining the fixed stability of the partition 5 during non-liquid hammer operation of the compressor. The annular weld is used to seal the corresponding gap to prevent the communication between the working chamber and the buffer chamber 7 from being disrupted by channels other than the communication channel. The annular weld is located on the side of the partition 5 closest to the working chamber to ensure that when liquid hammer occurs, the annular weld is broken under tensile force, allowing the partition 5 to be released from the annular groove 14, thereby breaking the fixed relationship. In a specific implementation, the retaining ring 13, the partition 5, and the annular weld are preferably all made of stainless steel. In this application, when the annular weld connection is broken under a pressure differential, the amount of debris generated and entering the working chamber due to the breakage can be effectively reduced, thereby reducing the risk of scratches on the inner wall of the piston chamber 2 and the piston ring assembly 3 caused by this debris before the piston ring assembly 3 stops moving. Since the response speed of the above clearance volume expansion process is affected by the weight of the partition 5, and the partition 5 also needs to have an appropriate thickness to match the requirements for its pressure resistance and stability, a better application is: setting the partition 5 to a stainless steel plate and a base plate laminated structure, and the side of the partition 5 close to the working chamber is a stainless steel plate, and the side of the partition 5 away from the working chamber is a non-stainless steel plate and a metal plate base plate, the fixing ring 13 is a stainless steel ring, and the girth weld welding molding material is stainless steel. Under such an application, after the girth weld is destroyed under the pressure difference, it not only has the effect of reducing the amount of debris generated (the amount of debris generated after the girth weld of the ductile iron plate is destroyed is also small, but the ductile iron plate is a material difficult to weld). , it is difficult to form the ring weld and it is difficult to achieve the corresponding sealing). At the same time, compared with setting the partition 5 as a stainless steel plate as a whole, on the basis of the same pressure resistance and stability characteristics, the mass of the above laminated structure is smaller (taking the substrate as 45 carbon steel plate, cast steel plate, ductile iron plate, and the stainless steel plate as 304 / 316 austenitic stainless steel plate as an example, in order to withstand the same pressure difference and maintain stability under alternating pressure difference, the partition 5 made of stainless steel needs to be designed to be thicker, and its material density is also slightly higher than that of the substrate. Therefore, the final weight will be greater than the partition 5 of the laminated structure). Therefore, while reducing debris, this application can reduce the overall mechanical inertia of the partition 5 to facilitate the response speed.

[0085] In a more specific application, the annular groove 14 is provided with a guide groove of a frustum structure on the side close to the buffer chamber 7, and the end with a larger diameter of the frustum structure is close to the working chamber. In this way, when the middle part of the partition 5 is recessed to a certain extent under the pressure difference on both sides, the supporting capacity of the back side of the annular groove 14 on the partition 5 is weakened, so that the partition 5 can be more smoothly removed from the annular groove 14.

[0086] Example 3:

[0087] This embodiment is further refined based on the embodiment 1:

[0088] The communication channel is a communication groove 6 provided on the wall of the piston chamber 2. The communication groove 6 is a strip-shaped groove on the wall of the piston chamber. One end of the communication groove 6 is located in the working chamber, and the other end of the communication groove 6 is located in the buffer chamber 7.

[0089] There are multiple communicating grooves 6 , which are arranged at intervals in the circumferential direction of the piston chamber 2 .

[0090] The above provides a specific form of connecting channel setting: a connecting groove 6 set on the wall of the piston chamber 2 and across the partition 5 is used as the connecting channel. Such a connecting channel can be obtained by surface processing the wall of the piston chamber 2, which not only has high processing efficiency but also has the characteristics of high connecting channel processing precision; the connecting grooves 6 are set as multiple and arranged at intervals in the circumferential direction of the piston chamber 2 to achieve: relative to the partition 5, the connecting grooves 6 form multiple connecting channels in the circumferential direction of the partition 5. In this way, compared with the use of a single connecting groove 6 (a single connecting groove 6 has the same fluid conductivity as the multiple connecting grooves 6 used in this scheme), in the process of establishing a pressure difference, the more balanced airflow in the circumference of the partition 5 can not only reduce the impact of the airflow on the vibration of the partition 5, but also, this method is beneficial to establishing pressure balance at various positions in the working chamber (mainly the compressor suction process) and the buffer chamber 7 (mainly the compressor compression process).

[0091] Example 4:

[0092] This embodiment is further refined based on the embodiment 1:

[0093] The communication channel is a communication hole 18 provided on the side wall of the piston chamber 2. One end of the communication hole 18 communicates with the exhaust hole 8 of the cylinder 4, and the other end of the communication hole 18 communicates with the buffer chamber 7.

[0094] The device further includes an adjusting cone 19 disposed in the communicating hole 18 , and the adjusting cone 19 is used to adjust the fluid conduction capacity of the communicating hole 18 .

[0095] The above solution provides another form of connection channel setting, specifically: the connection hole 18 realizes the connection between the working chamber and the buffer chamber 7 through the orifices at both ends thereof, and is set to also include an adjusting cone 19, thereby solving the problem that the connection groove 6 cannot adjust the connection capacity between the working chamber and the buffer chamber 7. As mentioned above, this solution uses the partition 5 and the buffer chamber 7 to achieve the anti-liquid hammer effect, but it will sacrifice the efficiency of the compressor. For the discharge stage of well flow materials such as no liquid water, low liquid water content or low water vapor content, the possibility of liquid hammer in the compressor is low. In such a case, it is not easy for the fixed relationship of the partition 5 to be destroyed. Therefore, it can be set to reduce the fluid conductivity of the connection hole 18 through the adjusting cone 19 (the pressure difference between the two sides of the partition 5 is established faster under such application, and the smaller liquid content in the working chamber can trigger the destruction of the fixed relationship), so as to reduce the loss of gas in the pressurization stage of the cylinder structure and the amount of gas injected into the working chamber from the buffer chamber 7 during the suction stage, so as to achieve the purpose of optimizing the efficiency of the compressor; for liquid During the discharge phase of well fluids with high water or water vapor content, the compressor is more likely to experience liquid hammer. In such situations, if the conductivity of the connecting hole 18 is low, the fixed relationship of the partition 5 is more likely to be broken, triggering the liquid hammer protection. Therefore, the adjusting cone 19 can be used to increase the fluid conductivity of the connecting hole 18 (this operation slows down the pressure differential across the partition 5, requiring a larger amount of liquid in the working chamber to trigger the breaking of the fixed relationship). This method reduces compressor efficiency and discharge pressure, enhances the cylinder structure's adaptability to liquid content in the working chamber (the working chamber will have a higher liquid content when liquid hammer occurs), and reduces the equipment failure rate caused by the breaking of the fixed relationship. Those skilled in the art will know that the adjusting cone 19 can adopt a needle valve stem structure, and the fluid conductivity of the connecting hole 18 can be adjusted by adjusting the insertion depth of the adjusting cone 19 in the connecting hole 18. The purpose of setting the orifice on one side of the connecting hole 18 on the exhaust hole 8 is to achieve: according to the relative positions of the working chamber and the buffer chamber 7, the connecting hole 18 should be set as a bent hole, so the processing of the connecting hole 18 should adopt a scheme of first setting multiple intersecting process holes, and then partially blocking some of the process holes to form the connecting hole 18. When a structure is adopted in which the process hole is connected to the hole wall at the inlet position of the exhaust hole 8 (it is necessary to avoid the exhaust valve installed in the exhaust hole 8 and in any open or closed state affecting the connection between the exhaust hole 8 and the working chamber), based on the basic configuration of the cylinder structure in which the air inlet hole 1 on the cylinder 4 and the exhaust hole 8 are generally set on the side of the cylinder 4, the process hole can be set as a horizontal hole parallel to the axis of the cylinder 4 and a vertical hole along the radial direction of the cylinder 4. The horizontal hole intersects with the vertical hole, and the outer orifices of the horizontal hole and the vertical hole are blocked by plugs respectively to complete the forming of the connecting hole 18.

[0096] Example 5:

[0097] This embodiment is further refined based on the embodiment 1:

[0098] It also includes a pressure sensor 20 mounted on the cylinder 4, and the pressure sensor 20 is used to monitor the pressure in the working chamber;

[0099] Also included is a position sensor for monitoring the position of the piston ring assembly 3 in the cylinder 4;

[0100] It also includes a pressure relief hole 22 provided on the cylinder 4, and the pressure relief hole 22 is equipped with an electromagnetic pressure relief valve for controlling the on and off of the pressure relief hole 22;

[0101] It also includes a control module, which is signal-connected to the pressure sensor 20, the position sensor, and the electromagnetic pressure relief valve. The signal connection is as follows: the control module receives the detection results of the pressure sensor 20 and the position sensor, and transmits an action control signal to the electromagnetic pressure relief valve;

[0102] The control module is configured to determine whether the pressure of the current working chamber exceeds the limit based on the monitoring values ​​of the position sensor and the monitoring values ​​of the pressure sensor 20, and when the judgment result is that the pressure exceeds the limit, trigger the transmission of an action control signal to the electromagnetic pressure relief valve to open the electromagnetic pressure relief valve.

[0103] As described above, when the anti-liquid surge protection is triggered by the partition 5 and the buffer chamber 7, the original position of the partition 5 in the piston chamber 2 is destroyed. At this time, the compression efficiency and exhaust pressure of the compressor are greatly affected. It is necessary to enable the compressor again after restoring the partition 5. As a pre-protection for the partition 5 to trigger the anti-liquid surge protection, the above provides an electronically controlled pre-protection scheme. Specifically, the scheme utilizes the characteristics of the position of the piston ring assembly 3 in the cylinder 4 to associate with the gas compression ratio in the working chamber, and utilizes the comparison result of the pressure associated with the pressure monitoring value and the position monitoring value to determine whether to trigger the electromagnetic pressure relief valve to open. For example, when the working chamber occupies the remaining gap due to liquid water, resulting in a significant increase in the internal pressure growth rate of the working chamber of the piston ring assembly 3 during the compression stroke, it can be determined that the internal pressure of the working chamber at the current position of the piston ring assembly 3 exceeds the limit, thereby triggering the electromagnetic pressure relief valve to open to release the internal pressure of the working chamber, thereby achieving the purpose of the pre-protection to reduce the probability of the partition 5 triggering the anti-liquid surge protection.

[0104] It is easy to understand that the above electronic control scheme and the partition 5 scheme are parallel schemes for realizing anti-liquid hammer protection. The electronic control scheme as the front-stage protection is intended to achieve: in the prior art, the piston ring assembly 3 requires less time to complete a cycle of movement, and the cylinder 4 has the characteristic of temperature instability. This requires the relevant sensor to complete a signal detection, which not only requires a short time and a high signal pickup frequency, but also has the characteristic that the detection accuracy is less affected by temperature. When high-precision, high-dynamic performance sensors and temperature compensation schemes are adopted, the impact of the detection delay link and detection accuracy on the liquid hammer protection response speed can be effectively guaranteed. However, the cost of using sensors is very high, which is not conducive to the economic efficiency of the compressor. Therefore, on this basis, when the partition 5 scheme is further adopted as the back-stage protection, the system requirements for the above electronic control scheme can be effectively reduced to reduce the setting cost of the electronic control scheme, and under the joint action of the above two levels of protection, the effective anti-liquid hammer protection purpose can be achieved while taking into account economy.

[0105] More specifically, the preferred position sensor is a magnetostrictive displacement sensor of general accuracy, and the pressure sensor 20 is a sensor based on piezoelectric crystals and metal diaphragms. Such sensors have the characteristics of low result response delay, and the electromagnetic pressure relief valve also has the characteristics of rapid action response.

[0106] Regarding the control module, to reduce computational response delay, the specific logic of the control module may be: calculating the difference or rate of change between two adjacent pressure monitoring results, as well as the difference or rate of change between two adjacent position monitoring results, then dividing the differences or rates of change (the pressure detection result divided by the position detection result) to determine whether the current working chamber pressure exceeds the limit. This logic can be implemented in software or using an analog differential circuit (requiring signal type support: analog differential circuits are only suitable for processing analog signals). However, when selecting a specific solution, priority should be given to a solution that balances cost control and computational time.

[0107] Example 6:

[0108] Based on Example 1, this embodiment provides an anti-liquid hammer compressor, including a compressor cylinder structure, wherein the compressor cylinder structure is the compressor cylinder structure provided in Example 1;

[0109] The piston ring assembly 3 includes a ring body 9 made of a metal plate, which is connected to the piston rod. It also includes a self-lubricating layer 10 made of a polymer self-lubricating material. The self-lubricating layer 10 is an annular structure and is sleeved on the outside of the ring body 9. It also includes a plurality of first sealing rings 11 installed on the outer periphery of the self-lubricating layer 10. The first sealing rings 11 are arranged in sequence in the axial direction of the piston ring assembly 3. The first sealing rings 11 serve as axial sealing rings between the piston ring assembly 3 and the wall of the working chamber.

[0110] The above-mentioned anti-liquid hammer compressor is a compressor including the compressor cylinder structure. In summary, this solution has the characteristic of effectively optimizing the response speed of the clearance volume expansion process. Furthermore, in view of the sand-producing characteristics of the well fluid, in order to reduce the impact of the relevant abrasive particles in the fluid on the piston ring assembly 3 and the cavity wall of the piston cavity 2, a self-lubricating layer 10 such as a polytetrafluoroethylene material is provided on the outer periphery of the ring body 9, and a first sealing ring 11 is provided on the basis of the self-lubricating layer 10, aiming to achieve: utilizing the characteristic that abrasive particles can be embedded in the polytetrafluoroethylene self-lubricating polymer material, reducing the content of free abrasive particles in the piston cavity 2, so as to reduce the impact of the abrasive particles on the cavity wall of the piston cavity 2.

[0111] Example 7:

[0112] This embodiment provides a wellhead natural gas compression method based on the embodiment 1. The method is implemented based on the compressor cylinder structure described in the embodiment 1. The method is as follows:

[0113] The piston ring assembly 3 reciprocates in the working chamber to compress the natural gas at the wellhead;

[0114] During the process of the piston ring assembly 3 compressing the wellhead natural gas, the communicating passage is used to connect the working chamber and the buffer chamber 7, thereby reducing the pressure difference on both sides of the partition plate 5;

[0115] When the pressure difference exceeds the set threshold, the fixed relationship of the partition 5 in the piston chamber 2 is destroyed under the pressure difference on both sides of the partition 5, and the partition 5 can move toward the side where the buffer chamber 7 is located under the pressure difference;

[0116] The compressor cylinder adopts a single-cylinder single-stage compression method that compresses the wellhead natural gas only when the piston ring assembly 3 moves forward or backward, or adopts a single-cylinder two-stage compression method in which an air inlet hole 1 and an air outlet hole 8 are provided at both ends of the cylinder 4, and the wellhead natural gas on one side of the piston ring assembly 3 is compressed when the piston ring assembly 3 moves forward or backward;

[0117] When the compressor cylinder adopts a single-cylinder single-stage compression mode, the partition plate 5 is arranged on the side of the piston ring assembly 3 away from the piston rod. The piston ring assembly 3 compresses the wellhead natural gas when it moves toward the side where the partition plate 5 is located. The channel opening of the communication channel arranged on the cylinder barrel 4 is located at the end of the working chamber close to the partition plate 5.

[0118] When the compressor cylinder adopts a single-cylinder two-stage compression method, the partition 5 is arranged on the side of the piston ring assembly 3 away from the piston rod, and the channel opening of the communication channel arranged on the cylinder 4 is located at the end of the working chamber close to the partition 5, and the working chamber is used as: the working chamber between the partition 5 and the piston ring assembly 3 is used as the first-level compression chamber, and the working chamber on the side of the piston ring assembly 3 away from the partition 5 is used as the second-level compression chamber. The second-level compression chamber is used to re-pressurize the wellhead natural gas after the first-level compression chamber is pressurized.

[0119] The above method is a method for realizing wellhead natural gas compression based on the compressor cylinder structure, and further explains the setting method of the partition 5 under the specific compression mode of the compressor cylinder: the buffer chamber 7 is located on the side of the piston ring assembly 3 away from the piston rod, so that after the fixed relationship is destroyed, the conductivity between the formed working chamber and the buffer chamber 7 is used to quickly prevent the internal pressure in the piston chamber 2 from further increasing. Compared with setting the buffer chamber 7 on the side of the cylinder 4 or the end where the piston rod is located, the purpose of optimizing the response speed of the clearance volume expansion process is achieved. The selection of the position of the channel mouth of the above connecting channel enables the piston ring assembly 3 to use the connecting channel to establish a continuously increasing pressure difference on both sides of the partition 5 throughout the compression stroke.

[0120] The above scheme illustrates the functional relationship between the working chambers on both sides of the piston ring assembly 3 at different stages of wellhead natural gas pressurization when the compressor cylinder adopts a single-cylinder two-stage compression method. It is intended to address the following problems: the medium processed by the secondary compression chamber is the medium discharged from the primary compression chamber, stored in the buffer tank, and separated from the water and gas. Therefore, the primary compression chamber is more susceptible to the influence of the water content of the well flow and liquid hammer occurs. In this context, a partition 5 is provided to provide liquid hammer protection for the primary compression chamber. Such a pressurization method not only has the high compression efficiency of the single-cylinder two-stage compression method, but also uses the partition 5 to provide high-response liquid hammer protection for the wellhead natural gas, so that the wellhead natural gas compression not only has the characteristics of high compression efficiency, but also has the characteristics of reliable liquid hammer protection.

[0121] The above content is a further detailed description of the present invention in conjunction with specific preferred embodiments, and the specific embodiments of the present invention cannot be considered to be limited to these descriptions. For those skilled in the art to which the present invention belongs, other embodiments derived without departing from the technical solution of the present invention should be included in the scope of protection of the present invention.

Claims

1. A liquid-surge-proof compressor cylinder structure, comprising a cylinder barrel (4) and a piston ring assembly (3), wherein a piston chamber (2) is provided on the cylinder barrel (4), and characterized in that: It also includes a partition (5) fixed inside the piston chamber (2), wherein the partition (5) separates the piston chamber (2) into a working chamber and a buffer chamber (7) in the axial direction of the piston chamber (2), and the piston ring assembly (3) is arranged in the working chamber. It also includes a communication channel arranged on the cylinder (4) and / or the partition (5), wherein the communication channel is used to realize mutual communication between the working chambers and the buffer chamber (7) on both sides of the partition (5); The partition (5) is configured such that: when the pressure difference between the working chamber pressure and the buffer chamber (7) pressure exceeds a set threshold, the partition (5) is broken in its fixed relationship in the piston chamber (2) under the pressure difference on both sides thereof, and the partition (5) can move toward the side where the buffer chamber (7) is located under the pressure difference; A fixing ring (13) is provided on the outer periphery of the partition (5), and the fixing ring (13) is an annular structure coaxial with the partition (5). A second sealing ring (15) is provided on the outer side of the fixing ring (13), and the second sealing ring (15) is used to achieve axial sealing of the gap between the fixing ring (13) and the wall of the piston chamber (2); It also includes an end plate (21) fixed to the end of the cylinder (4), and the fixing ring (13) is connected to the end plate (21) via an adjustment mechanism, and the adjustment mechanism is used to adjust the position of the fixing ring (13) on the axis of the piston chamber (2); The adjusting mechanism comprises a plurality of adjusting screws (16), the adjusting screws (16) being uniformly distributed in a ring shape relative to the axis of the fixing ring (13), each adjusting screw (16) passing through the fixing ring (13) and the end plate (21), the adjusting screws (16) being threadedly connected to the end plate (21), the adjusting screws (16) passing through the fixing ring (13) through a through hole provided on the fixing ring (13), and the adjusting screws (16) being clearance-matched with the through hole; Each adjusting screw (16) is provided with a snap ring (12) for limiting the position of the fixing ring (13) in the axial direction of the adjusting screw (16); Each adjusting screw (16) is equipped with a spring tube (17), which is sleeved on the outside of the adjusting screw (16), one end of the spring tube (17) is supported on the fixing ring (13), and the other end is supported on the inner wall of the end plate (21); Also included is a locking nut threadedly connected to the adjusting screw (16) and adapted to abut against the outer wall of the end plate (21); The partition (5) is a laminated structure of a stainless steel plate and a substrate. The side of the partition (5) close to the working chamber is made of a stainless steel plate, and the side of the partition (5) away from the working chamber is a substrate, which is a No. 45 carbon steel plate.

2. The anti-liquid-surge compressor cylinder structure according to claim 1, characterized in that: The inner wall of the fixing ring (13) is provided with an annular groove (14) coaxial with the fixing ring (13), and the edge of the partition (5) is embedded in the annular groove (14). A side of the partition (5) close to the working chamber is also provided with an annular weld, and the annular weld realizes the welding connection between the partition (5) and the fixing ring (13) and the sealing of the gap between the partition (5) and the fixing ring (13).

3. The anti-liquid hammer compressor cylinder structure according to claim 1, characterized in that: The communication channel is a communication groove (6) provided on the cavity wall of the piston cavity (2), the communication groove (6) being a strip-shaped groove on the cavity wall, one end of the communication groove (6) being located in the working cavity, and the other end of the communication groove (6) being located in the buffer cavity (7); There are a plurality of communicating grooves (6), and the communicating grooves (6) are arranged at intervals in the circumferential direction of the piston chamber (2).

4. The anti-liquid hammer compressor cylinder structure according to claim 1, characterized in that: The communication channel is a communication hole (18) provided on the side wall of the piston chamber (2), one end of the communication hole (18) is communicated with the exhaust hole (8) of the cylinder barrel (4), and the other end of the communication hole (18) is communicated with the buffer chamber (7); It also includes an adjusting cone (19) arranged in the communicating hole (18), wherein the adjusting cone (19) is used to adjust the fluid conduction capacity of the communicating hole (18).

5. The anti-liquid hammer compressor cylinder structure according to claim 1, characterized in that: Also included is a pressure sensor (20) mounted on the cylinder (4), wherein the pressure sensor (20) is used to monitor the pressure in the working chamber; Also included is a position sensor for monitoring the position of the piston ring assembly (3) in the cylinder (4); It also includes a pressure relief hole (22) provided on the cylinder barrel (4), wherein the pressure relief hole (22) is provided with an electromagnetic pressure relief valve for controlling the on / off of the pressure relief hole (22); It also includes a control module, the control module is signal-connected to the pressure sensor (20), the position sensor, and the electromagnetic pressure relief valve, the signal connection being: the control module receives detection results from the pressure sensor (20) and the position sensor, and transmits an action control signal to the electromagnetic pressure relief valve; The control module is configured to determine whether the pressure of the current working chamber exceeds the limit based on the monitoring value of the position sensor and the monitoring value of the pressure sensor (20); when the judgment result is that the pressure exceeds the limit, trigger the transmission of an action control signal to the electromagnetic pressure relief valve to open the electromagnetic pressure relief valve.

6. A liquid-surge-proof compressor, comprising a compressor cylinder structure, characterized in that: The compressor cylinder structure is the compressor cylinder structure provided by any one of claims 1 to 5; The piston ring assembly (3) includes a ring body (9) made of a metal plate, the ring body (9) is connected to the piston rod, and also includes a self-lubricating layer (10) made of a polymer self-lubricating material, the self-lubricating layer (10) is an annular structure and is sleeved on the outside of the ring body (9), and also includes a plurality of first sealing rings (11) installed on the periphery of the self-lubricating layer (10), the first sealing rings (11) are arranged in sequence in the axial direction of the piston ring assembly (3), and the first sealing rings (11) serve as axial sealing rings between the piston ring assembly (3) and the wall of the working chamber.

7. A method for compressing natural gas at a wellhead, characterized in that: The method is implemented based on the compressor cylinder structure according to any one of claims 1 to 5, and the method is: The piston ring assembly (3) reciprocates in the working chamber to compress the wellhead natural gas; During the process of the piston ring assembly (3) compressing the wellhead natural gas, the pressure difference on both sides of the partition plate (5) is reduced by utilizing the communication function of the working chamber and the buffer chamber (7) played by the communication channel; When the pressure difference exceeds a set threshold, the fixed relationship of the partition (5) in the piston chamber (2) is destroyed under the pressure difference on both sides of the partition (5), and the partition (5) can move toward the side where the buffer chamber (7) is located under the pressure difference; The compressor cylinder adopts a single-cylinder single-stage compression method that compresses wellhead natural gas only when the piston ring assembly (3) moves forward or backward, or adopts a single-cylinder two-stage compression method that provides an air inlet (1) and an air outlet (8) at both ends of the cylinder (4) to compress the wellhead natural gas on one side of the piston ring assembly (3) when the piston ring assembly (3) moves forward or backward; When the compressor cylinder adopts a single-cylinder single-stage compression mode, the partition plate (5) is arranged on the side of the piston ring assembly (3) away from the piston rod, and the piston ring assembly (3) compresses the wellhead natural gas when it moves toward the side where the partition plate (5) is located. The channel opening of the communication channel arranged on the cylinder barrel (4) is located at one end of the working chamber close to the partition plate (5); When the compressor cylinder adopts a single-cylinder two-stage compression mode, the partition (5) is arranged on the side of the piston ring assembly (3) away from the piston rod, and the channel opening of the communication channel arranged on the cylinder (4) is located at one end of the working chamber close to the partition (5), and the working chamber is used as: the working chamber between the partition (5) and the piston ring assembly (3) is used as a first-stage compression chamber, and the working chamber on the side of the piston ring assembly (3) away from the partition (5) is used as a second-stage compression chamber, and the second-stage compression chamber is used to re-pressurize the wellhead natural gas after the first-stage compression chamber is pressurized.

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