Mobile pipeline gas recovery apparatus and method

Abstract

The present application belongs to the technical field of long-distance natural gas pipeline engineering, and discloses a mobile pipeline gas recovery equipment. The equipment comprises a mobile platform and a natural gas compressor set. The natural gas compressor set is installed on the mobile platform and comprises a natural gas engine and a compression mechanism. The compression mechanism can access the residual natural gas in the working pipeline and supply a part of the residual natural gas to the natural gas engine as fuel after increasing to a preset pressure. The natural gas engine drives the compression mechanism to continuously operate to inject the pressurized natural gas into the downstream pipeline through a second interface. The equipment can be flexibly moved in a wide range to complete the recovery of residual natural gas in the working pipeline, reduce greenhouse gas emissions, and use the residual natural gas as energy, which is beneficial to meet the operation requirements of uncertain recovery locations and field operations. The compression mechanism overcomes the defect that the pressure of the residual natural gas decreases with discharge, reduces the venting volume, and improves the recovery efficiency of the pipeline gas.

Description

Technical Field

[0001] This invention relates to the field of natural gas long-distance pipeline engineering technology, and in particular to a mobile pipeline gas recovery device and a pipeline gas recovery method. Background Technology

[0002] my country's gas pipeline network is vast, dense, and complex. The eastern pipeline network was built earlier and has a long service life, resulting in heavy maintenance tasks. Meanwhile, the central and western pipeline networks are undergoing gradual expansion and interconnection, leading to a large infrastructure workload and an increasingly heavy nationwide maintenance burden. Traditionally, when carrying out pipeline maintenance, expansion, or interconnection work, the natural gas in the pipelines being worked on needs to be vented to ensure construction safety. However, this process often results in large amounts of natural gas being directly vented or burned through flares, causing serious environmental pollution (such as carbon dioxide from direct combustion and methane from vented natural gas, both of which exacerbate the greenhouse effect) and deviating from the national dual-carbon goals.

[0003] Currently, the main methods for reducing venting and recovery in long-distance pipelines in China are limited. One method is to use stationary reciprocating compressor units at pipeline compressor stations to extract natural gas from the pipeline to reduce pressure. However, this method is limited by location and the inlet pressure of the reciprocating compressor units. Typically, when the pressure drops to approximately 4.5 MPa, the remaining natural gas still needs to be vented through a vent riser or by burning it with a vent flare. Another method is to reduce the natural gas pressure in the pipeline by distributing it to downstream users, thereby reducing the amount of venting. However, this method is also limited by the minimum distribution pressure required by users, and the pressure reduction time is relatively long.

[0004] With the continuous rise in natural gas prices, the economic losses caused by natural gas venting during the aforementioned maintenance and repair operations are becoming increasingly significant. Although China has adopted relatively mature technical solutions for the recovery of associated gas from oil and gas fields, such as compressed natural gas (CNG) storage, liquefied natural gas (LNG) storage, and underground gas storage facilities (UNGS), these solutions are mainly suitable for small-scale, continuous natural gas recovery at fixed locations. They are not suitable for special operational scenarios such as long-distance pipeline venting recovery, where the operation location is uncertain, the field is open, the single recovery volume is large, and the recovery time requirement is short.

[0005] Based on the above, there is an urgent need for a mobile pipeline gas recovery device and a pipeline gas recovery method to solve the aforementioned technical problems. Summary of the Invention

[0006] The purpose of this invention is to provide a mobile pipeline gas recovery device and pipeline gas recovery method, which can reduce the waste of natural gas and the pollution caused to the environment. At the same time, it can be applied to special operation scenarios such as venting recovery where the operation location is uncertain, the field operation is carried out, the single recovery volume is large, and the recovery time requirement is short.

[0007] To achieve this objective, the present invention adopts the following technical solution:

[0008] A mobile pipeline gas recovery device is used to inject residual natural gas in a working pipeline into a downstream pipeline. The working pipeline is provided with a first interface, and the downstream pipeline is provided with a second interface. The mobile pipeline gas recovery device includes: a mobile platform; and a natural gas compressor unit. The natural gas compressor unit is installed on the mobile platform and includes a pipeline system, a natural gas engine, and a compression mechanism. The pipeline system is connected to the first interface, the second interface, the natural gas engine, and the compression mechanism. The compression mechanism can extract residual natural gas in the working pipeline through the pipeline system and the first interface, and after increasing the pressure to a preset level, supply a portion of the residual natural gas to the natural gas engine. The natural gas engine uses a portion of the pressurized residual natural gas as fuel and drives the compression mechanism to continuously operate, so as to inject another portion of the pressurized residual natural gas into the downstream pipeline through the second interface.

[0009] Preferably, the natural gas compressor unit includes two compression mechanisms, which are respectively configured as a first compression mechanism and a second compression mechanism. The pipeline system also includes a three-way control valve assembly and a manifold outlet pipe. The outlet end of the first compression mechanism, the inlet end of the second compression mechanism, and the inlet end of the manifold outlet pipe are all connected to the three-way control valve assembly. The three-way control valve assembly can selectively connect the first compression mechanism to at least one of the second compression mechanism and the manifold outlet pipe. The manifold outlet pipe has a first outlet and a second outlet. The first outlet is connected to the second interface, and the second outlet is connected to the natural gas engine.

[0010] Preferably, the natural gas compressor unit further includes a first washing tank and a second washing tank, wherein the first washing tank is connected between the first interface and the first compression mechanism, and the second washing tank is connected between the three-way control valve group and the second compression mechanism.

[0011] Preferably, the first washing tank and the second washing tank are provided with coalescing filter elements.

[0012] Preferably, the natural gas compressor unit further includes a first cooler and a second cooler. The first cooler is connected between the outlet end of the first compression mechanism and the three-way control valve group, and the outlet end of the first cooler is connected to the merging outlet pipe. The second cooler is connected between the outlet end of the second compression mechanism and the merging outlet pipe.

[0013] Preferably, the merging outlet pipe is equipped with a pressure reducing valve, which is located downstream of the first cooler and the second cooler, and upstream of the first outlet and the second outlet.

[0014] Preferably, the mobile pipeline gas recovery device further includes a third cooler for reducing the temperature of the natural gas engine. The first and second coolers are finned tube air coolers, and the third cooler is a plate-fin air cooler.

[0015] Preferably, the mobile pipeline gas recovery equipment further includes: an outer enclosure installed on the mobile platform, the natural gas compressor unit disposed inside the outer enclosure, and an upward-opening door and a downward-opening door on the side of the outer enclosure; and / or, a compressor oil heater for heating the compressor mechanism; and / or, an engine oil-water heater for heating the engine; and / or, a heating cable for heating the first washing tank and the second washing tank; and / or, a first generator connected to the natural gas engine, the natural gas engine capable of driving the first generator to supply electrical energy; and / or, a second generator using fossil fuels and capable of supplying electrical energy; and / or, a storage battery for supplying electrical energy.

[0016] Preferably, the mobile pipeline gas recovery device further includes:

[0017] A fixing member, which is L-shaped and includes a vertical part and a horizontal part that are fixedly connected, wherein the vertical part is detachably connected to the mobile platform and the horizontal part is welded to the natural gas compressor unit; and / or a hydraulic support, which is installed on the mobile platform and is capable of extending and retracting in the vertical direction, and is used to abut against the ground to fix the mobile platform.

[0018] The pipeline gas recovery method, implemented using the aforementioned mobile pipeline gas recovery equipment, includes:

[0019] The pipeline network is isolated to form an upstream pipeline, an operating pipeline, and a downstream pipeline; residual natural gas is taken from the operating pipeline, pressurized, and a portion of the residual natural gas is injected into the downstream pipeline, while the other portion of the residual natural gas is used as fuel to continuously draw residual natural gas from the operating pipeline, pressurize the residual natural gas, and inject the residual natural gas into the downstream pipeline to supply energy.

[0020] The beneficial effects of this invention are that the aforementioned mobile pipeline gas recovery equipment can be moved flexibly and extensively along the pipeline network, and residual natural gas can be used locally as an energy source, which is beneficial for meeting the operational needs of uncertain recovery locations and field operations. Simultaneously, the compression mechanism pressurizes the residual natural gas, overcoming the defect that the pressure of residual natural gas decreases as it is discharged. This allows the pressurized residual natural gas to be effectively injected into downstream pipelines, thereby reducing venting, minimizing natural gas waste and environmental pollution, and avoiding the time required for venting. This improves the efficiency of pipeline gas recovery, making it particularly suitable for operational scenarios with large single recovery volumes and short recovery time requirements. Attached Figure Description

[0021] Figure 1 This is a structural diagram of the mobile pipeline recycling equipment provided by the present invention;

[0022] Figure 2 This is a schematic diagram showing the connection between the mobile pipeline recycling equipment and the working pipeline provided by the present invention;

[0023] Figure 3 This is a schematic diagram of the structure of the natural gas compressor unit in this invention;

[0024] Figure 4 yes Figure 3 A magnified view of the area to the left of the dashed line;

[0025] Figure 5 yes Figure 3 A magnified view of the area to the right of the dashed line;

[0026] Figure 6 This is a detailed structural diagram of the exhaust shut-off valve assembly in this invention;

[0027] Figure 7 This is a structural diagram of the first and second coolers in this invention;

[0028] Figure 8 This is a schematic diagram showing the connection between the mobile platform and the natural gas compressor unit in this invention;

[0029] Figure 9 This is a schematic diagram of the structure of the outer enclosure in this invention.

[0030] In the diagram: 100, First shut-off valve; 101, Second shut-off valve; 102, Upstream pipeline; 103, Working pipeline; 1031, First interface; 104, Downstream pipeline; 1041, Second interface; 105, High-pressure hose;

[0031] 1. Mobile platform; 11. Hydraulic support; 111. Sleepers; 12. Outer enclosure; 121. Upward-opening door; 122. Downward-opening door; 13. Fasteners; 131. Vertical section; 132. Horizontal section;

[0032] 2. Natural gas compressor unit; 201. First inlet; 202. Second inlet; 203. First outlet; 204. Second outlet; 205. Third outlet; 206. Fourth outlet; 207. Fifth outlet; 208. Inlet shut-off valve assembly; 209. Inlet bypass valve assembly; 210. First scrubber tank; 211. First cone filter; 212. First buffer container; 213. First compression mechanism; 214. Second buffer container; 215. First cooler; 216. Three-way control valve assembly; 217. Second scrubber tank; 218. Second cone filter; 219. Third buffer container; 220. Second compression mechanism; 22 1. Fourth buffer container; 222. Second cooler; 223. Second check valve; 224. Exhaust shut-off valve assembly; 225. Vent valve assembly; 226. First check valve; 227. Loading valve assembly; 228. Pressure detector; 229. Temperature detector; 230. Pressure reducing valve; 231. Natural gas engine; 232. Third cooler; 233. First branch pipe; 234. Second branch pipe; 235. Loading branch pipe; 236. Three-way valve; 237. Valve position switch - open; 238. Valve position switch - closed; 239. Signal indicator; 240. Solenoid valve; 250. Instrument air / natural gas; 21. Base; 22. Rubber pad. Detailed Implementation

[0033] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention, and not all of the structures.

[0034] In the description of this invention, unless otherwise explicitly specified and limited, the terms "connected," "linked," and "fixed" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0035] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0036] In the description of this embodiment, the terms "upper," "lower," "right," etc., refer to the orientation or positional relationship shown in the accompanying drawings. They are used only for ease of description and simplification of operation, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention. In addition, the terms "first" and "second" are used only for distinction in description and have no special meaning.

[0037] The following is based on the appendix Figure 1 To be continued Figure 9 This invention introduces the mobile pipeline gas recovery device and pipeline gas recovery method provided by the present invention.

[0038] like Figures 1 to 2 As shown, in this embodiment, the mobile pipeline gas recovery device mainly includes a mobile platform 1 and a natural gas compressor unit 2, which can inject residual natural gas in the working pipeline 103 into the downstream pipeline 104. It should be noted that the working pipeline 103 and the downstream pipeline 104 mentioned herein are formed by installing a first shut-off valve 100 and a second shut-off valve 101 in the pipeline network (i.e., the gas transmission pipeline), thereby isolating the pipeline network to form an upstream pipeline 102, a working pipeline 103, and a downstream pipeline 104. The first shut-off valve 100 can isolate the upstream pipeline 102 and the working pipeline 103, while the second shut-off valve 101 can isolate the working pipeline 103 and the downstream pipeline 104. At this time, the working pipeline 103 contains the residual natural gas described in the background art.

[0039] Specifically, in this embodiment, the mobile platform 1 adopts a chassis vehicle, such as a Class II chassis vehicle, which has a driver's cab, steering system, braking system, power system, etc., and can carry and move the natural gas compressor unit 2, thereby enabling the mobile pipeline gas recovery equipment to be moved in a wide range and flexibly along the pipeline network, thus meeting the operational needs of uncertain recovery locations and field operations.

[0040] like Figure 3As shown, in this embodiment, the natural gas compressor unit 2 is installed on the mobile platform 1 and includes a pipeline system, a natural gas engine 231, and a compression mechanism. The pipeline system is connected to the first interface 1031, the second interface 1041, the natural gas engine 231, and the compression mechanism. The compression mechanism can take residual natural gas from the working pipeline 103 through the pipeline system and the first interface 1031, and after increasing it to a preset pressure, supply a portion of the residual natural gas to the natural gas engine 231. The natural gas engine 231 takes a portion of the pressurized residual natural gas as fuel and drives the compression mechanism to operate continuously, so as to inject another portion of the pressurized residual natural gas into the downstream pipeline 104 through the second interface 1041. In this embodiment, the natural gas compressor unit includes a reciprocating compressor, which includes a cylinder, piston, and other structures. The aforementioned compression mechanism refers to multiple components such as the cylinder and piston that can work together to achieve gas pressurization. The process of working together is that the reciprocating motion of the piston in the cylinder causes the cylinder volume to change periodically and achieve gas pressurization. In other words, this reciprocating compressor is a positive displacement reciprocating compressor, which can achieve a high pressure ratio.

[0041] Preferably, both the first interface 1031 and the second interface 1041 are connected to the natural gas compressor unit 2 via seamless steel pipes and high-pressure hoses 105, effectively isolating the vibration of the natural gas compressor unit 2 from the impact on the station pipeline. Furthermore, the high-pressure hose 105 connection is a flexible connection, ensuring that the natural gas compressor unit 2 and the gas transmission pipeline are adjustable in both height and horizontal direction, reducing the workload of connection. While the high-pressure hose 105 is easy to connect, it is heavier and more expensive than the seamless steel pipe. Therefore, the length of the high-pressure hose 105 is controlled within 4m to ensure both weight and ease of installation. Further, the seamless steel pipe is connected with a ball valve to control the inflow and outflow of natural gas.

[0042] Specifically, when using this mobile pipeline gas recovery equipment, the pipeline system and the first interface 1031 are first connected. Since the residual natural gas still has a certain pressure when the working pipeline 103 is just cut off, under the action of pressure, the residual natural gas will flow into the natural gas engine 231 and the downstream pipeline 104 through the compression mechanism, thereby driving the natural gas engine 231 to operate and achieving the effect of discharging the residual natural gas in the working pipeline 103. The natural gas engine 231 and the compression mechanism are connected by transmission. As the residual natural gas in the working pipeline 103 continues to flow out and operate, the pressure in the working pipeline 103 will gradually decrease. At this time, driven by the natural gas engine 231, the compression mechanism continues to operate, extracting and pressurizing the residual natural gas in the working pipeline 103. This allows a portion of the pressurized residual natural gas to be injected into the natural gas engine 231 and meet the needs of the natural gas engine 231. The other portion of the pressurized residual natural gas can meet the corresponding pressure requirements and can be well injected into the downstream pipeline 104 through the second interface 1041, thereby overcoming the phenomenon of the residual natural gas being vented due to the gradual decrease in pressure in the working pipeline 103.

[0043] The aforementioned mobile pipeline gas recovery equipment allows for flexible movement along the pipeline network and on-site utilization of residual natural gas as an energy source, which is beneficial for meeting the operational needs of uncertain recovery locations and field operations. Simultaneously, the compression mechanism pressurizes the residual natural gas, overcoming the defect that the pressure decreases as the residual natural gas is discharged. This ensures that the pressurized residual natural gas can be effectively injected into the downstream pipeline 104, thereby reducing venting, minimizing natural gas waste and environmental pollution, and avoiding the time required for venting. This improves the efficiency of pipeline gas recovery, making it particularly suitable for operational scenarios with large single recovery volumes and short recovery time requirements.

[0044] Continue to refer to Figure 3As shown, preferably, in this embodiment, the natural gas compressor unit 2 includes two compression mechanisms, each including components such as cylinders and pistons to achieve gas pressurization. For ease of description, the two compression mechanisms are defined as the first compression mechanism 213 and the second compression mechanism 220, respectively. The pipeline system also includes a three-way control valve assembly 216 and a confluence outlet pipe. The outlet end of the first compression mechanism 213, the inlet end of the second compression mechanism 220, and the inlet end of the confluence outlet pipe are all connected to the three-way control valve assembly 216. The three-way control valve assembly 216 can selectively connect the first compression mechanism 213 to at least one of the second compression mechanism 220 and the confluence outlet pipe. The confluence outlet pipe has a first outlet 203 and a second outlet 204. The first outlet 203 is connected to the second interface 1041, and the second outlet 204 is connected to the natural gas engine 231. As the natural gas pressure in the working pipeline 103 gradually decreases, the three-way control valve assembly 216 can first meet the pressure boosting demand through the first compression mechanism 213. When the natural gas pressure decreases to a point where a single compression mechanism cannot boost it to the preset pressure, the three-way control valve assembly 216 connects the first compression mechanism 213 and the second compression mechanism 220 in series. This two-stage pressure boosting ensures that the natural gas can still be pressurized to the preset pressure, maintaining the fuel supply to the natural gas engine 231 and meeting the pressure demand for injection into the downstream pipeline 104. In this way, the effect of switching between primary and secondary compression can be achieved to meet different needs in different operational stages.

[0045] like Figure 3 As shown, in this embodiment, the pipeline system also includes multiple control valves such as a shut-off valve, a vent valve group 225, and a loading valve group 227, thereby controlling the flow direction of natural gas and pressurizing the natural gas in a single-stage or two-stage pressurization manner as needed. Figure 4 , Figure 5 They are Figure 3 Enlarged views of the left and right halves of the image; the following will be based on... Figures 3 to 5 The content shown provides a detailed description of the specific structure of natural gas compressor unit 2, combined with the specific operation process.

[0046] like Figure 3 , Figure 4As shown, the pipeline system has a first inlet 201 and the aforementioned first outlet 203 and second outlet 204 formed outside the natural gas compressor unit 2. The first inlet 201 can communicate with the first interface 1031, thereby connecting the residual natural gas in the working pipeline 103 to the natural gas compressor unit 2. The first outlet 203 is connected to the second interface 1041 and is used to inject the natural gas in the natural gas compressor unit 2 into the downstream pipeline 104. The second outlet 204 is connected to the natural gas engine 231 and can inject the natural gas in the natural gas compressor unit 2 into the natural gas engine 231 as fuel.

[0047] like Figure 4 As shown, between the first inlet 201 and the first compression mechanism 213, a first washing tank 210, a first conical filter 211, and a first buffer container 212 are sequentially arranged. Furthermore, between the first compression mechanism 213 and the three-way control valve assembly 216, a second buffer container 214 and a first cooler 215 are sequentially arranged. Similarly, as... Figure 5 As shown, a second washing tank 217, a second conical filter 218, and a third buffer container 219 are sequentially arranged between the three-way control valve group 216 and the second compression mechanism 220. A fourth buffer container 221 and a second cooler 222 are also sequentially arranged downstream of the second compression mechanism 220 and upstream of the first outlet 203 and the second outlet 204 (i.e., the merging gas outlet pipe). The first cooler 215 is also connected to the merging gas outlet pipe and is equipped with a first one-way valve 226 to prevent natural gas from flowing backwards from the merging gas outlet pipe to the first cooler 215.

[0048] The first washing tank 210 and the second washing tank 217 remove impurities and particulate matter from the natural gas, preventing these impurities from entering the compression mechanism and thus protecting it from damage. Preferably, in this embodiment, coalescing filter elements are also provided in the first washing tank 210 and the second washing tank 217. Compared to wire mesh filter elements, coalescing filter elements have a smaller diameter for the same filtration effect, which helps to reduce the diameter of the washing tanks, thus facilitating the mounting of the natural gas compressor unit 2 on the mobile platform 1. The first conical filter 211 and the second conical filter 218 further filter and clean the natural gas, better protecting the compression mechanism from damage caused by impurities.

[0049] The four buffer containers can absorb and release pressure fluctuations, making the gas pressure more stable, which is beneficial to the smooth operation of the compression mechanism and reduces the impact of sudden gas flow changes on the compression mechanism, thus extending the service life of the compression mechanism. Optionally, the first buffer container 212 is connected to a pressure detector 228 (as an intake pressure transmitter) to monitor the pressure ratio of the first compression mechanism 213 and the second compression mechanism 220. At the same time, some buffer containers are also connected to a temperature detector 229 to monitor whether they are within the normal temperature range.

[0050] Optionally, the pipeline system also forms a third outlet 205, a fourth outlet 206, and a fifth outlet 207 outside the natural gas compressor unit 2. The third outlet 205 serves as a vent for the natural gas compressor unit 2, allowing the natural gas remaining in the unit to be released after operation. The fourth outlet 206 and the fifth outlet 207 serve as drain outlets for the first scrubbing tank 210 and the second scrubbing tank 217, respectively, to discharge impurities and particulate matter collected by filtration.

[0051] Continue to refer to Figure 3 As shown, the pipeline system also includes an inlet shut-off valve assembly 208, which is located between the first inlet 201 and the first scrubbing tank 210 to control the inflow of natural gas. (Continue referring to...) Figure 4 As shown, the merging outlet pipe includes a first branch pipe 233 and a second branch pipe 234. Both the first branch pipe 233 and the second branch pipe 234 are connected to the outlet end of the second cooler 222. The first branch pipe 233 has two outlet ends, namely the first outlet 203 and the second outlet 204 mentioned above. The second branch pipe 234 has one outlet end, namely the third outlet 205 mentioned above. The pipeline system also includes an exhaust shut-off valve assembly 224, a second one-way valve 223, and a vent valve assembly 225. The exhaust shut-off valve assembly 224 is located on the first branch pipe 233 and can control whether natural gas flows into the downstream pipeline 104 and the natural gas engine 231. The second one-way valve 223 is also located on the first branch pipe 233 to prevent natural gas in the downstream pipeline 104 from flowing back into the second compression mechanism 220 assembly. The vent valve assembly 225 is located on the second branch pipe 234 and can control whether natural gas flows out of the natural gas compressor unit 2 through the third outlet 205. Optionally, in some other embodiments, the intake shut-off valve assembly 208 may also be disposed between the first inlet 201 and the first interface 1031, and the exhaust shut-off valve assembly 224 may also be disposed between the second outlet 204 and the second interface 1041. This invention does not specifically limit this, as long as it can play the function of controlling intake and exhaust.

[0052] Meanwhile, the pipeline system also includes a loading branch pipe 235, one end of which is connected to the merging exhaust pipe and the other end is connected to the first washing tank 210. The loading branch pipe 235 is equipped with a loading valve group 227 to control the opening and closing of the loading branch pipe 235.

[0053] During the preparation phase, the intake shut-off valve group 208, exhaust shut-off valve group 224 and vent valve group 225 are closed, and the three-way control valve group 216 and loading valve group 227 are opened. At this time, both ends of the first compression mechanism 213 and both ends of the second compression mechanism 220 (including each buffer container) are balanced with the external atmospheric pressure through the third outlet 205. The pressure can be detected by each pressure detector 228, thereby achieving self-testing.

[0054] After the self-test is completed, the preloading stage begins. During the preloading stage, natural gas is slowly injected into the natural gas compressor unit 2 through the first inlet 201, ensuring sufficient pressure within the cylinder during compressor startup to open the internal valves and prevent damage to the compressor. However, the cylinder pressure should not be too high, as excessive internal pressure will increase the startup load and cause startup difficulties. Preferably, in this embodiment, the pipeline system also includes a preloading branch pipe 235, one end of which is connected to the first inlet 201, and the other end to the first scrubbing tank 210, and is equipped with an intake bypass valve assembly 209. The intake bypass valve assembly 209 can control the opening and closing of the preloading branch pipe 235 and can control the preloading branch pipe 235 to input natural gas into the first scrubbing tank 210 at a lower pressure. Therefore, in this embodiment, the natural gas can be preloaded by first closing the intake shut-off valve group 208 and opening the intake bypass valve group 209. When the pressure detector 228 connected to the first buffer container 212 detects that the pressure has risen to 2 bar, the intake bypass valve group 209 is closed to avoid excessive pressure.

[0055] During the preloading phase, natural gas flows sequentially through the first compression mechanism 213 and the second compression mechanism 220 before entering the natural gas engine 231. At this point, the natural gas engine 231 can be started, driving the first compression mechanism 213 and the second compression mechanism 220 to compress the gas. In this embodiment, after the natural gas engine 231 starts smoothly, the intake bypass valve group 209 can be opened again to continuously supply natural gas through the preloading branch pipe 235. When the pressure difference between the internal pressure of the first buffer container 212 and the intake pressure (i.e., the pressure at the first inlet 201) is no greater than 20%, the intake shut-off valve group 208 can be opened and the intake bypass valve group 209 closed. This allows for slow gas intake during the preloading phase, ensuring a smooth loading of the natural gas engine 231 and preventing a sudden increase in air volume that could cause a drop in engine speed or even shutdown. After the intake shut-off valve group 208 opens, the exhaust shut-off valve group 224 also opens, completing the preloading phase and successfully starting the entire natural gas compressor unit 2. At this time, the intake shut-off valve group 208 and the exhaust shut-off valve group 224 are both open, while the loading valve group 227, the intake bypass valve group 209 and the vent valve group 225 are all closed.

[0056] Subsequently, when the natural gas engine 231 reaches the preset speed, the loading conditions are met, and the natural gas compressor unit 2 can enter the loading stage. During the loading stage, the loading valve group 227 is closed, and the natural gas engine 231 drives the compression mechanism (which can be at least one of the first compression mechanism 213 and the second compression mechanism 220) to pressurize the natural gas. When the pressure on the side of the second one-way valve 223 near the cooler is greater than the pressure on the side away from the cooler, it indicates that the natural gas compressor unit 2 has pressurized the natural gas to a level greater than the pressure in the downstream pipeline 104, and the natural gas can then be injected into the downstream pipeline 104 through the first outlet 203. Optionally, in this embodiment, the loading stage can begin when the engine reaches its rated speed of 1800 RPM (rated speed).

[0057] Specifically, in this embodiment, since the initial intake pressure is relatively high and the pressure ratio is between 1 and 3, in order to ensure a high recovery speed, the two compression mechanisms can be operated in parallel, i.e., a single-stage compression can be performed. For example, the three-way control valve group 216 is controlled to connect the second washing tank 217 and the first inlet 201, and to disconnect the first cooler 215 and the second washing tank 217, so that the natural gas entering from the first inlet 201 can be divided into two parts. One part flows into the confluence exhaust pipe after passing through the first washing tank 210, the first cone filter 211, the first buffer container 212, the first compression mechanism 213, the second buffer container 214, the first cooler 215 and the first one-way valve 226. The other part flows into the confluence exhaust pipe after passing through the second washing tank 217, the second cone filter 218, the third buffer container 219, the second compression mechanism 220, the fourth buffer container 221 and the second cooler 222.

[0058] As the recovery process proceeds, the intake pressure gradually decreases, and the pressure ratio of the compression mechanism gradually increases. When the ratio of the exhaust pressure (i.e., the pressure in the first branch pipe 233) to the pressure in the first buffer container 212 decreases to a preset value, it is necessary to enter the 1 / 2 stage switching phase to increase the output pressure from the first outlet 203. Specifically, this preset value must ensure the normal operation of the compression mechanism while also taking into account the recovery speed; therefore, in this embodiment, it is typically selected as 3.

[0059] Specifically, during the 1 / 2 stage switching phase, the intake shut-off valve assembly 208 and the exhaust shut-off valve assembly 224 are kept in their original positions. Then, the loading valve assembly 227 is gradually opened, allowing the compression mechanism to enter an unloaded state, thus preventing gas path blockage and overpressure problems caused by valve action during the loading switching process. Subsequently, the three-way control valve assembly 216 is controlled to disconnect the second washing tank 217 and the first inlet 201, and to connect the first cooler 215 and the second washing tank 217. At this time, the natural gas flowing out of the first cooler 215 is divided into two parts: one part flows into the converging exhaust pipe through the second compression mechanism 220, and the other part flows past the second compression mechanism 220 towards the first one-way valve 226. That is to say, at this time, the natural gas flowing through the natural gas compressor unit 2 undergoes primary compression and secondary compression. The natural gas that has undergone primary compression is located upstream of the first one-way valve 226, and the natural gas that has undergone secondary compression is located downstream of the first one-way valve 226. The first check valve 226 prevents natural gas from flowing back into the first cooler 215. However, since the pressure of natural gas after primary compression is lower than that after secondary compression, the natural gas after primary compression is insufficient to pass through the first check valve 226. Thus, the pipeline from the first cooler 215 to the first check valve 226 to the converging exhaust pipe achieves a "circuit break" effect.

[0060] At this point, the natural gas, after primary compression, gradually fills the space between the first cooler 215 and the first one-way valve 226, and can only enter the second compression mechanism 220 through the three-way control valve group 216. In other words, all the natural gas entering the natural gas compressor unit 2 passes through the first compression mechanism 213 and the second compression mechanism 220, achieving two-stage compression, and flows into the confluence exhaust pipe. Subsequently, the loading valve group 227 is closed, preventing the secondary compressed natural gas from flowing into the first scrubbing tank 210 through the loading branch pipe 235, ensuring that the exhaust pressure can increase, thereby allowing the natural gas compressor unit 2 to achieve a stable state and enter the stable operation phase. During the stable operation phase, natural gas can be recovered from the working pipeline 103 with high efficiency, and natural gas can be used for power supply, greatly reducing dependence on external energy sources.

[0061] Subsequently, when the ratio of exhaust pressure to intake pressure reaches a preset value, it signifies that recovery is complete, and the natural gas compressor unit 2 needs to enter the standby phase. For example, in this embodiment, the preset value is 9.

[0062] Specifically, when it is necessary to enter the standby phase, first close the intake shut-off valve assembly 208 and the exhaust shut-off valve assembly 224, then open the loading valve assembly 227 and the vent valve assembly 225. This allows the natural gas compressor unit 2 to connect with the outside environment through the vent valve assembly 225, gradually reducing the pressure until it reaches equilibrium with the outside environment. Subsequently, close the vent valve assembly 225 to enter the standby phase, waiting for the next recovery operation to be completed after the relocation.

[0063] It should be noted that in this embodiment, each valve assembly (such as the aforementioned inlet shut-off valve assembly 208, exhaust shut-off valve assembly 224, etc.) is composed of multiple individual valve bodies with different functions, such as ball valves, pressure reducing valves 230, three-way valves 236, etc., and can include instruments such as flow meters, level gauges, pressure detectors 228, and temperature detectors 229 as needed to monitor flow, pressure, etc. at specific locations. This invention does not impose specific limitations on these aspects. For example, as shown... Figure 6 As shown, the exhaust shut-off valve assembly 224 includes a pressure reducing valve 230, a three-way valve 236, an instrument air / natural gas valve 250, and a solenoid valve 240. It can reduce the pressure of natural gas and measure the flow rate and pressure of natural gas, thereby facilitating the regulation of exhaust pressure. Furthermore, the exhaust shut-off valve assembly 224 also includes a valve position switch - open 237 and a valve position switch - closed 238, both connected to signal indicators 239, and providing normally open and normally closed contact outputs for convenient control.

[0064] During the aforementioned operation, the compression mechanism (including the scrubbing tanks) changes from parallel processing to series processing, and the natural gas compression changes from a single stage to a two-stage process. It also features an automatic switching design between the first and second stages of compression, adapting to varying intake pressures to ensure that the exhaust pressure consistently meets the requirements of the downstream pipeline 104 and the natural gas engine 231. Simultaneously, the first scrubbing tank 210 and the second scrubbing tank 217 can perform filtration in parallel or sequentially, effectively reducing the filtration capacity requirements for each tank. This not only reduces the size of each tank, ensuring the mobility and flexible operation of the mobile pipeline gas recovery equipment, but also meets the filtration needs under all operating conditions.

[0065] And, as Figure 7 As shown, the arrangement of the two coolers (i.e., the first cooler 215 and the second cooler 222) also facilitates the placement of each cooler at the location corresponding to the compression mechanism, saving space, optimizing the heat dissipation path, improving pipeline routing, and simplifying maintenance. Preferably, both the first cooler 215 and the second cooler 222 are finned tube air coolers, located on one side of the corresponding compression mechanism, and equipped with multiple fans. When the heat dissipation demand is high, the fan speed increases and all fans operate; when the heat dissipation demand is low, the number and speed of the operating fans are gradually reduced. This ensures the relative stability of the compressed gas temperature and saves power consumption.

[0066] Continue to refer to Figure 3 As shown, in this embodiment, a nitrogen purging manifold is also provided. One end of the nitrogen purging manifold is configured as a second inlet 202, and the other end is connected to the inlet of the first washing tank 210 and the three-way control valve group 216. By introducing nitrogen through the second inlet 202, the interior of the natural gas compressor unit 2 can be purged and cleaned. The nitrogen purging manifold is equipped with a ball valve, which is used to connect and disconnect the nitrogen purging manifold.

[0067] Preferably, the second buffer container 214 and the fourth buffer container 221 are connected to the third outlet 205 respectively through a safety valve, which can directly discharge gas by venting when abnormal pressure occurs inside, protecting the structure of the natural gas compressor unit 2 from damage and avoiding the risk of explosion.

[0068] Optionally, the natural gas compressor unit 2 is also equipped with a third cooler 232, which is located on one side of the natural gas engine 231. The third cooler 232 is a plate-fin air cooler and is equipped with a variable frequency fan. For low-pressure, high-heat-load conditions, the plate-fin air cooler has high heat exchange efficiency, effectively reducing the power requirements of the variable frequency fan and helping to reduce the overall size of the third cooler 232.

[0069] Understandably, in order to supply power to various electrical components such as instruments, electronic control valves, and fans, the natural gas compressor unit 2 is also equipped with a first generator. The first generator is connected to the natural gas engine 231 and can also supply electrical energy under the drive of the natural gas engine 231.

[0070] Optionally, the natural gas compressor unit 2 also includes a battery or a second generator. The second generator uses fossil fuels such as diesel or gasoline to supply electrical energy to various electrical components when the natural gas engine 231 is not running. Of course, in some other embodiments, for example, when the mobile platform 1 is a Class II chassis vehicle, it has its own battery and power generation capacity. Therefore, when the natural gas engine 231 is not running, the various electrical components can also choose to draw power from the mobile platform 1.

[0071] Preferably, in this embodiment, the natural gas compressor unit 2 further includes a compressor oil heater and an engine oil-water heater. These two heaters can heat the compressor and the natural gas engine 231 to achieve a thermal engine effect. Furthermore, the natural gas compressor unit 2 also includes a heating cable, which can heat the first scrubbing tank 210 and the second scrubbing tank 217 to meet the filtration requirements under low-temperature conditions.

[0072] Optionally, in this embodiment, the mobile platform 1 is further equipped with a hydraulic support 11 and sleepers 111. The hydraulic support 11 is disposed on the bottom surface of the mobile platform 1, and sleepers 111 are installed at its lower end. When the mobile platform 1 is in place, the hydraulic support 11 can extend and retract vertically, thereby moving the sleepers 111 downwards and abutting against the ground to form a fixed support, ensuring that the deviation of the natural gas compressor unit 2 from the horizontal direction is within 5%, thus improving the stability of the mobile pipeline gas recovery equipment during operation. When relocation is required, the hydraulic support 11 can move the sleepers 111 upwards and separate them from the ground, thereby avoiding interference with the normal movement of the mobile platform 1.

[0073] Furthermore, in this embodiment, the natural gas compressor unit 2 also includes a base 21, which and the outer enclosure 12 can form a frame structure for fixing and protecting the various compression mechanisms, washing tanks, pipelines and other specific structures to prevent loosening or damage during operation.

[0074] Optionally, in this embodiment, as Figure 8As shown, the base 21 is also connected to a fixing member 13. The fixing member 13 is L-shaped and includes a vertical part 131 and a horizontal part 132 that are fixedly connected. The vertical part 131 and the moving platform 1 are detachably connected by bolts. The horizontal part 132 is welded to the base 21 of the natural gas compressor unit 2. This facilitates the overall disassembly and installation of the natural gas compressor unit 2 and ensures a fixed connection between the natural gas compressor unit 2 and the moving platform 1. Exemplarily, in this embodiment, multiple fixing members 13 are connected to both sides of the moving platform 1 along its length, thereby stably installing the natural gas compressor unit 2 on the moving platform 1.

[0075] Preferably, a rubber pad 22 is also provided between the base 21 and the mobile platform 1 to reduce the negative impact of vibration on the mobile platform 1 and reduce noise during operation.

[0076] Preferably, such as Figure 9 As shown, the mobile platform 1 is also equipped with an outer enclosure 12, which protects the natural gas compressor unit 2. The outer enclosure 12 has an upward-opening door 121 and a downward-opening door 122, which are vertically aligned and located on the same side of the outer enclosure 12. The upward-opening door 122 is connected to the outer enclosure 12 by hinges. When opened, the upward-opening door 121 is fixed by a support rod fixed to the outer enclosure 12, and the downward-opening door 122 is fixed by a pull-out support rod installed on the mobile platform 1, forming a step platform for convenient operation of the natural gas compressor unit 2.

[0077] This invention also provides a method for recovering pipeline gas, using the aforementioned mobile pipeline gas recovery equipment. The method specifically includes:

[0078] The pipeline network is isolated to form an upstream pipeline 102, an operating pipeline 103, and a downstream pipeline 104. Residual natural gas is taken from the operating pipeline 103, pressurized, and a portion of the residual natural gas is injected into the downstream pipeline 104. The remaining portion of the residual natural gas is used as fuel to continuously supply energy by taking residual natural gas from the operating pipeline 103, pressurizing the residual natural gas, and injecting the residual natural gas into the downstream pipeline 104.

[0079] Specifically, the isolation of the pipeline network is achieved using a first shut-off valve 100 and a second shut-off valve 101. Subsequently, the working pipeline 103 is connected to the first interface 1031 of the mobile pipeline gas recovery equipment, and the downstream pipeline 104 is connected to the second interface 1041 of the mobile pipeline gas recovery equipment, thus enabling the recovery operation.

[0080] More specifically, the recovery operation can be carried out according to the above-mentioned operation preparation stage, preloading stage, loading stage, level 1 / 2 switching stage, stable operation stage and standby stage, which will not be elaborated in this invention.

[0081] This pipeline gas recovery method enables the on-site use of residual natural gas as an energy source, which is beneficial for meeting the operational needs of uncertain recovery locations and field operations. The residual natural gas is pressurized and discharged, and the automatic switching design of the primary / secondary compression mechanism overcomes the defect that the pressure of residual natural gas decreases as it is discharged. This allows the residual natural gas to be well injected into the downstream pipeline 104 after pressurization, thereby reducing the amount of venting, reducing the waste of natural gas and the pollution to the environment, and avoiding the time required for venting. It also improves the efficiency of pipeline gas recovery, and is especially suitable for operational scenarios with large single recovery volumes and short recovery time requirements.

[0082] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art will be able to make various obvious changes, readjustments, and substitutions without departing from the scope of protection of the present invention. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A mobile pipeline gas recovery device for injecting residual natural gas in a working pipeline (103) into a downstream pipeline (104), wherein the working pipeline (103) is provided with a first interface (1031) and the downstream pipeline (104) is provided with a second interface (1041), characterized in that, The mobile pipeline gas recovery equipment includes: Mobile platform (1); A natural gas compressor unit (2) is installed on the mobile platform (1) and includes a pipeline system, a natural gas engine (231) and a compression mechanism. The pipeline system is connected to the first interface (1031), the second interface (1041), the natural gas engine (231) and the compression mechanism. The compression mechanism can take residual natural gas in the working pipeline (103) through the pipeline system and the first interface (1031), and supply a portion of the residual natural gas to the natural gas engine (231) after increasing it to a preset pressure. The natural gas engine (231) takes a portion of the pressurized residual natural gas as fuel and drives the compression mechanism to operate continuously so as to inject another portion of the pressurized residual natural gas into the downstream pipeline (104) through the second interface (1041).

2. The mobile pipeline gas recovery device according to claim 1, characterized in that, The natural gas compressor unit (2) includes two compression mechanisms, which are respectively configured as a first compression mechanism (213) and a second compression mechanism (220). The pipeline system also includes a three-way control valve assembly (216) and a manifold outlet pipe. The outlet end of the first compression mechanism (213), the inlet end of the second compression mechanism (220), and the inlet end of the manifold outlet pipe are all connected to the three-way control valve assembly (216). The three-way control valve assembly (216) can selectively connect the first compression mechanism (213) with at least one of the second compression mechanism (220) and the manifold outlet pipe. The manifold outlet pipe has a first outlet (203) and a second outlet (204). The first outlet (203) is connected to the second interface (1041), and the second outlet (204) is connected to the natural gas engine (231).

3. The mobile pipeline gas recovery device according to claim 2, characterized in that, The natural gas compressor unit (2) further includes a first washing tank (210) and a second washing tank (217). The first washing tank (210) is connected between the first interface (1031) and the first compression mechanism (213), and the second washing tank (217) is connected between the three-way control valve group (216) and the second compression mechanism (220).

4. The mobile pipeline gas recovery device according to claim 3, characterized in that, Both the first washing tank (210) and the second washing tank (217) are equipped with coalescing filter elements.

5. The mobile pipeline gas recovery device according to claim 4, characterized in that, The natural gas compressor unit (2) further includes a first cooler (215) and a second cooler (222). The first cooler (215) is connected between the outlet end of the first compression mechanism (213) and the three-way control valve group (216), and the outlet end of the first cooler (215) is connected to the merging outlet pipe. The second cooler (222) is connected between the outlet end of the second compression mechanism (220) and the merging outlet pipe.

6. The mobile pipeline gas recovery device according to claim 5, characterized in that, The merging outlet pipe is equipped with a pressure reducing valve (230), which is located downstream of the first cooler (215) and the second cooler (222), and upstream of the first outlet (203) and the second outlet (204).

7. The mobile pipeline gas recovery device according to claim 5, characterized in that, The mobile pipeline gas recovery equipment also includes a third cooler (232) for reducing the temperature of the natural gas engine (231). The first cooler (215) and the second cooler (222) are finned tube air coolers, and the third cooler (232) is a plate-fin air cooler.

8. The mobile pipeline gas recovery device according to claim 3, characterized in that, The mobile pipeline gas recovery equipment also includes: An outer enclosure (12) is installed on the mobile platform (1), and the natural gas compressor unit (2) is located inside the outer enclosure (12). The outer enclosure (12) has an upward-opening door (121) and a downward-opening door (122) on its side; and / or, Compression mechanism oil heater, the compression mechanism oil heater being used to heat the compression mechanism; and / or, Engine oil-water heater, the engine oil-water heater being used to heat the engine; and / or, The heat tracing cable is used to heat the first washing tank (210) and the second washing tank (217); and / or, A first generator, which is driveably connected to the natural gas engine (231), the natural gas engine (231) being capable of driving the first generator to supply electrical energy; and / or, The second generator uses fossil fuels and is capable of supplying electrical energy; And / or, A storage battery, which is used to supply electrical energy.

9. The mobile pipeline gas recovery device according to claim 3, characterized in that, The mobile pipeline gas recovery equipment also includes: A fixing member (13), said fixing member (13) being L-shaped and comprising a vertical part (131) and a horizontal part (132) fixedly connected, said vertical part (131) being detachably connected to said moving platform (1), said horizontal part (132) being welded to said natural gas compressor unit (2); and / or, A hydraulic support (11) is installed on the mobile platform (1) and is capable of extending and retracting in the vertical direction. The hydraulic support (11) is used to abut against the ground to fix the mobile platform (1).

10. A pipeline gas recovery method, implemented using a mobile pipeline gas recovery device as described in any one of claims 1-9, characterized in that, The pipeline gas recovery method includes: The pipeline network is divided to form an upstream pipeline (102), an operating pipeline (103), and a downstream pipeline (104); Residual natural gas is taken from the working pipeline (103), pressurized, and a portion of the residual natural gas is injected into the downstream pipeline (104). The remaining portion of the residual natural gas is used as fuel to continuously supply energy for taking residual natural gas from the working pipeline (103), pressurizing residual natural gas, and injecting residual natural gas into the downstream pipeline (104).

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