A loading device for recovering CNG
By introducing a depressurization module and a preheating module in series in the CNG onboard unit, and using the residual pressure power generation system to drive the expansion generator to supply power to the heating system, the problem of hydrate blockage caused by the gas temperature dropping to the freezing point is solved, and the economic and environmental benefits of the utilization of scattered gas resources are improved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- PIPECHINA SOUTH CHINA CO
- Filing Date
- 2025-08-04
- Publication Date
- 2026-07-24
AI Technical Summary
Existing CNG recovery loading devices suffer from hydrate blockage during decompression due to gas temperatures dropping below freezing, limiting the economic and environmental benefits of resource utilization.
The design employs a series connection of a pressure-reducing module and a preheating module. The residual pressure power generation system drives an expansion generator to generate electricity to supply the heating system, preventing the gas temperature from dropping to freezing point. The high-pressure natural gas itself drives power generation and heating, reducing external power consumption.
It effectively avoids the problem of hydrate blockage, improves the economic and environmental benefits of utilizing scattered gas resources, and reduces external power consumption.
Smart Images
Figure CN224551318U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of CNG loading natural gas station technology, and in particular to a CNG recovery loading device. Background Technology
[0002] During oil and gas field development, scattered natural gas resources with dispersed and intermittent characteristics are often generated, including gas produced from marginal wells, low-production wells, and associated gas from oil fields. Due to their small production scale, insufficient regional demand, or distance from pipeline networks, these gas sources are often forced to be flared, leading to resource waste and environmental pollution. To achieve resource utilization, the commonly used solution is vehicle-mounted compressed natural gas (CNG): low-pressure gas is compressed to 20 MPa using wellhead pressurization equipment, and then transported by dedicated vehicles to loading stations with pipeline access for unloading.
[0003] Existing CNG recovery loading devices typically include a filtration unit, a multi-stage pressure reduction module, and a metering and flow regulation module. Compressed natural gas enters the pipeline network sequentially through the filtration unit, the multi-stage pressure reduction module, and the metering and flow regulation module. A preheating module can optionally heat the compressed natural gas before the pressure reduction module. When the gas source pressure (approximately 20 MPa) is higher than the pipeline operating pressure (5-10 MPa), a pressure reduction loading mode is adopted. The high-pressure gas sequentially passes through the filtration unit, the preheating system (raising the medium temperature to above 50°C to avoid the risk of subsequent cooling), the pressure reduction module (achieving a step-by-step pressure reduction from 20 MPa to the pipeline pressure range, this process is accompanied by a significant Joule-Thomson effect leading to a sudden temperature drop), and the metering and flow regulation system before being injected into the pipeline network. When the residual gas pressure in the transport vehicle is lower than the pipeline pressure, the system switches to a pressurization loading mode (process 2), where the 0-10 MPa low-pressure gas is filtered, pressurized by the compressor unit, and metered and regulated before injection.
[0004] However, the existing depressurization and loading process has obvious technical defects: in order to prevent hydrate blockage caused by the gas temperature dropping below freezing point during the depressurization process, a large amount of heat energy must be consumed through the preheating module for temperature compensation, which seriously restricts the economic and environmental benefits of the utilization of scattered gas resources.
[0005] Therefore, it is urgent to recycle CNG uploading devices to solve the above problems. Utility Model Content
[0006] The purpose of this invention is to provide an onboard device for recovering CNG, in order to solve the problem in related technologies that in order to prevent hydrate blockage caused by the gas temperature dropping below the freezing point during decompression, a large amount of heat energy must be consumed through a preheating module for temperature compensation, which seriously restricts the economic and environmental benefits of the utilization of scattered gas resources.
[0007] This utility model provides a CNG recycling loading device, which includes:
[0008] Pressure reducing module, through which compressed natural gas flows;
[0009] The preheating module includes a heating system and a residual pressure power generation system. The heating system is connected in series with the pressure reducing module and is located upstream of the pressure reducing module. The residual pressure power generation system is connected in parallel on both sides of the pressure reducing module. The residual pressure power generation system includes a first shut-off valve and an expansion generator connected in series. The expansion generator is used to supply power to the heating system.
[0010] As a preferred technical solution for the CNG recycling loading device, the preheating module further includes a regulating system, which is connected in parallel with the pressure reducing module. The regulating system also includes a second shut-off valve and a pressure regulating valve, which are connected in series.
[0011] As a preferred technical solution for the CNG recovery on-board device, the residual pressure power generation system also includes a pressure monitoring component, which can monitor the pressure at the inlet and outlet of the expansion generator.
[0012] As a preferred technical solution for the CNG recovery loading device, the pressure monitoring component includes a first pressure gauge and a second pressure gauge, wherein the first pressure gauge is located at the inlet of the first shut-off valve and the second pressure gauge is located at the outlet of the expansion generator.
[0013] As a preferred technical solution for the CNG recovery loading device, the pressure monitoring component includes a first pressure transmitter and a second pressure transmitter. The first pressure transmitter is located at the inlet of the first shut-off valve, and the second pressure transmitter is located at the outlet of the expansion generator.
[0014] As a preferred technical solution for the CNG recycling on-board unit, the heating system includes a heater and a switching valve, the switching valve being able to control the current flow between the expansion generator and the heater.
[0015] As a preferred technical solution for the CNG recovery loading device, the heating system further includes an energy storage device. The switching valve includes a first position, a second position, a third position, and a fourth position. In the first position, the expansion generator and the heater are connected in series. In the second position, the expansion generator and the energy storage device are connected in series. In the third position, the energy storage device and the heater are connected in series. In the fourth position, the expansion generator, the heater, and the energy storage device are disconnected from each other.
[0016] As a preferred technical solution for the CNG recycling loading device, the heater is an electromagnetic heater.
[0017] As a preferred technical solution for the CNG recovery on-board unit, the heating system further includes a temperature sensor for monitoring the natural gas temperature at the inlet of the pressure reducing module.
[0018] As a preferred technical solution for the CNG recovery on-board device, the preheating module further includes a filter assembly, the pipeline between the heating system and the pressure reducing module is connected to the air inlet of the filter assembly, and the air inlet of the residual pressure power generation system is connected to the air outlet of the filter assembly.
[0019] The beneficial effects of this utility model are as follows:
[0020] This invention provides a CNG recovery loading device, which includes a pressure reducing module and a preheating module. Compressed natural gas flows through the pressure reducing module. The preheating module includes a heating system and a residual pressure power generation system. The heating system is connected in series with the pressure reducing module and is located upstream of the pressure reducing module. The residual pressure power generation system is connected in parallel on both sides of the pressure reducing module and includes a first shut-off valve and an expansion generator connected in series. The expansion generator supplies power to the heating system. During the process of delivering high-pressure natural gas from a CNG transport vehicle to the pipeline network using this CNG recovery loading device, the pressure reducing module needs to depressurize the high-pressure natural gas to meet the pressure requirements of the input pipeline network. During this process, the gas temperature drops sharply, easily forming hydrates that clog the pipeline. To avoid this problem, a portion of the high-pressure natural gas entering the pressure reducing module is fed into the residual pressure power generation system. The high-pressure natural gas drives the expansion generator to generate electricity, which powers the heating system to raise the temperature of the high-pressure natural gas. When the heated high-pressure natural gas is reintroduced into the pressure reducing module, the temperature of the natural gas is prevented from dropping to freezing point, thus avoiding the problem of hydrate blockage. In this process, no external power grid or external power source is required to power the heating system. The expansion generator is driven by high-pressure natural gas to provide electricity, which effectively improves the economic and environmental benefits of the utilization of scattered gas resources. Attached Figure Description
[0021] Figure 1 This is a schematic diagram of the CNG recycling loading device in an embodiment of this utility model.
[0022] In the picture:
[0023] 1. Pressure reduction module;
[0024] 21. Heating system; 211. Heater; 212. Switch valve; 213. Energy storage device; 22. Residual pressure power generation system; 221. First shut-off valve; 222. Expander generator; 2221. Generator; 2222. Expander; 2231. First pressure gauge; 2232. Second pressure gauge; 2233. First pressure transmitter; 2234. Second pressure transmitter; 23. Regulation system; 231. Second shut-off valve; 232. Pressure regulating valve; 24. Filter assembly; 25. Metering and flow controller. Detailed Implementation
[0025] The technical solution of this utility model will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this utility model. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this utility model.
[0026] In the description of this utility model, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this utility model and for simplifying the description, 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 this utility model. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. The terms "first position" and "second position" refer to two different positions. Moreover, "above," "on top of," and "over" the first feature in relation to the second feature includes the first feature directly above and diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "under," and "below" the first feature in relation to the second feature includes the first feature directly below and diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.
[0027] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; 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; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.
[0028] The embodiments of this utility model are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this utility model, and should not be construed as limiting this utility model.
[0029] like Figure 1 As shown, this embodiment provides a CNG recovery loading device, which includes a pressure reducing module 1 and a preheating module. Compressed natural gas flows through the pressure reducing module 1. The preheating module includes a heating system 21 and a residual pressure power generation system 22. The heating system 21 is connected in series with the pressure reducing module 1 and is located upstream of the pressure reducing module 1. The residual pressure power generation system 22 is connected in parallel on both sides of the pressure reducing module 1. The residual pressure power generation system 22 includes a first shut-off valve 221 and an expander generator 2221 connected in series. The expander generator 2221 is used to supply power to the heating system 21. During the process of delivering high-pressure natural gas from a CNG transport vehicle to the pipeline network through this CNG recovery loading device, the pressure reducing module 1 needs to reduce the pressure of the high-pressure natural gas to meet the pressure requirements of the input pipeline network. During this process, the gas temperature drops sharply, easily leading to hydrate formation and pipeline blockage. To avoid this problem, a portion of the high-pressure natural gas entering the pressure-reducing module 1 is fed into the residual pressure power generation system 22. The high-pressure natural gas drives the expansion generator 2221 to generate electricity, which powers the heating system 21 to raise the temperature of the high-pressure natural gas. When the heated high-pressure natural gas is reintroduced into the pressure-reducing module 1, the temperature of the natural gas is prevented from dropping to freezing point, thus avoiding hydrate blockage. In this process, no external power grid or external power source is required to power the heating system 21; the high-pressure natural gas drives the expansion generator 2221 to provide electricity, effectively improving the economic and environmental benefits of utilizing scattered gas resources.
[0030] Optionally, the natural gas flowing through the expander generator 2221 is depressurized and then merged with the natural gas flowing out of the depressurization module 1 before flowing into the pipeline network together.
[0031] Optionally, the expander generator 2221 includes a generator 2221 and an expander 2222. High-pressure natural gas flows into the expander 2222, which in turn drives the generator 2221 to generate electricity.
[0032] Optionally, when the expander generator 2221 malfunctions and cannot work properly, the first shut-off valve 221 is temporarily closed. At this time, the expander generator 2221 no longer participates in the work. When the CNG recovery loading device is resting, the expander generator 2221 can be repaired without delaying the operation of the CNG recovery loading device.
[0033] Optionally, the regulating system 23 is connected in parallel with the pressure reducing module 1. The regulating system 23 also includes a second shut-off valve 231 and a pressure regulating valve 232, which are connected in series. In this embodiment, when the expander generator 2221 malfunctions and cannot operate normally, the first shut-off valve 221 is temporarily closed. At this time, to avoid hydrate blockage in the pressure reducing module 1 when all high-pressure natural gas passes through it, the second shut-off valve 231 is opened. By adjusting the opening size of the pressure regulating valve 232, the flow rate of high-pressure natural gas passing through the pressure regulating valve 232 is adjusted, thus working together with the pressure regulating module to regulate the pressure of the high-pressure natural gas. This effectively improves the problem of hydrate blockage that easily occurs in the pressure reducing module 1 when only it is working.
[0034] Optionally, when the first shut-off valve 221 is in the open state and the expander generator 2221 is working normally, the second shut-off valve 231 is in the open state.
[0035] Optionally, the waste pressure power generation system 22 also includes a pressure monitoring component, which can monitor the pressure at the inlet and outlet of the expander generator 2221. In this embodiment, the pressure monitoring component monitors the pressure at the inlet and outlet of the expander generator 2221 to obtain the pressure difference between the inlet and outlet, thereby determining the operating state of the expander generator 2221. By adjusting the flow rate of the pressure module, the pressure difference between the inlet and outlet of the expander generator 2221 can be adjusted, thereby regulating the operating state of the expander generator 2221.
[0036] Optionally, the pressure monitoring component includes a first pressure gauge 2231 and a second pressure gauge 2232. The first pressure gauge 2231 is located at the inlet of the first shut-off valve 221, and the second pressure gauge 2232 is located at the outlet of the expander generator 2221. In this embodiment, operators can view the readings of the first pressure gauge 2231 and the second pressure gauge 2232 on-site to determine the pressure difference, facilitating on-site adjustment of the flow rate of the pressure reducing module 1.
[0037] Optionally, the pressure monitoring component includes a first pressure transmitter 2233 and a second pressure transmitter 2234. The first pressure transmitter 2233 is located at the inlet of the first shut-off valve 221, and the second pressure transmitter 2234 is located at the outlet of the expander generator 2221. In this embodiment, the first pressure transmitter 2233 and the second pressure transmitter 2234 can remotely transmit the monitored pressure values to determine the pressure difference, thereby facilitating remote adjustment of the flow rate of the pressure reducing module 1 by the operator.
[0038] Optionally, the heating system 21 includes a heater 211 and a switching valve 212, which controls the current flow between the expansion generator 2221 and the heater 211. In this embodiment, when the high-pressure natural gas upstream of the heating system 21 is at a high temperature and hydrates are not generated by the pressure reducing module 1, the high-pressure natural gas can be left unheated, and the power supply from the expansion generator 2221 to the heater 211 can be cut off by the switching valve 212.
[0039] Optionally, the heating system 21 further includes an energy storage device 213. The switching valve 212 includes a first position, a second position, a third position, and a fourth position. In the first position, the expander generator 2221 and the heater 211 are connected in series; in the second position, the expander generator 2221 and the energy storage device 213 are connected in series; in the third position, the energy storage device 213 and the heater 211 are connected in series; and in the fourth position, the expander generator 2221, the heater 211, and the energy storage device 213 are disconnected from each other. In this embodiment, when the heater 211 needs to heat the high-pressure natural gas and the expander generator 2221 is working normally, the switching valve 212 is switched to the first position, at which time the expander generator 2221 directly supplies power to the heater 211. When the heater 211 does not need to heat the high-pressure natural gas, the switching valve 212 is switched to the second position, at which time the expander generator 2221 directly charges the energy storage device 213. When the expander generator 2221 malfunctions and the high-pressure natural gas needs heating, the switch valve 212 is switched to the third position, at which point the energy storage unit 213 directly supplies power to the heater 211. When the CNG recovery on-board unit is idle, the switch valve 212 is switched to the fourth position, at which point the expander generator 2221, heater 211, and energy storage unit 213 are disconnected from each other.
[0040] Optionally, the heater 211 is an electromagnetic heater 211. In this embodiment, the electromagnetic heater 211 includes a magnetic coil assembly and a double-layer heat dissipation pipe. The inner pipe of the double-layer heat dissipation pipe is used to transport the high-pressure natural gas to be heated, and the outer pipe of the double-layer heat dissipation pipe is used to wind the magnetic coil assembly. The expansion generator 2221 and the accumulator are selectively electrically connected to the magnetic coil assembly. When the magnetic coil assembly is energized, it can heat the outer pipe. The outer pipe transfers heat to the inner pipe, thereby heating the high-pressure natural gas in the inner pipe. The electromagnetic heater 211 is prior art and will not be described in detail here.
[0041] Optionally, the heating system 21 also includes a temperature sensor for monitoring the natural gas temperature at the inlet of the pressure reducing module 1. In this embodiment, the temperature sensor can monitor the natural gas temperature at the inlet of the pressure reducing module 1. When the temperature is lower than a preset value, the switching valve 212 switches to a first position or a third position to enable the heater 211 to operate.
[0042] Optionally, the preheating module further includes a filter assembly 24. The pipeline between the heating system 21 and the pressure reducing module 1 is connected to the inlet end of the filter assembly 24, and the inlet end of the residual pressure power generation system 22 is connected to the outlet end of the filter assembly 24. In this embodiment, the filter assembly 24 can filter the natural gas entering the residual pressure power generation system 22, preventing impurities in the natural gas from damaging the residual pressure power generation system 22. The specific structure of the filter assembly 24 is prior art and will not be described further here.
[0043] Optionally, the CNG recovery loading device also includes a metering and flow controller 25, which is used to monitor the amount of natural gas entering the pipeline network.
[0044] Obviously, the above embodiments of this utility model are merely examples for clearly illustrating the present utility model, and are not intended to limit the implementation of the present utility model. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this utility model should be included within the protection scope of the claims of this utility model.
Claims
1. A CNG recycling loading device, characterized in that, include: Pressure reducing module (1), through which compressed natural gas flows; The preheating module includes a heating system (21) and a residual pressure power generation system (22). The heating system (21) is connected in series with the pressure reducing module (1) and is located upstream of the pressure reducing module (1). The residual pressure power generation system (22) is connected in parallel on both sides of the pressure reducing module (1). The residual pressure power generation system (22) includes a first shut-off valve (221) and an expansion generator (222) connected in series. The expansion generator (222) is used to supply power to the heating system (21).
2. The CNG recycling loading device according to claim 1, characterized in that, The preheating module also includes an adjustment system (23), which is connected in parallel with the pressure reducing module (1). The adjustment system (23) also includes a second shut-off valve (231) and a pressure regulating valve (232), which are connected in series.
3. The CNG recycling loading device according to claim 1, characterized in that, The residual pressure power generation system (22) also includes a pressure monitoring component, which is capable of monitoring the pressure at the inlet and outlet of the expansion generator (222).
4. The CNG recycling loading device according to claim 3, characterized in that, The pressure monitoring component includes a first pressure gauge (2231) and a second pressure gauge (2232). The first pressure gauge (2231) is located at the inlet of the first shut-off valve (221), and the second pressure gauge (2232) is located at the outlet of the expander generator (222).
5. The CNG recycling loading device according to claim 3, characterized in that, The pressure monitoring assembly includes a first pressure transmitter (2233) and a second pressure transmitter (2234). The first pressure transmitter (2233) is located at the inlet of the first shut-off valve (221), and the second pressure transmitter (2234) is located at the outlet of the expander generator (222).
6. The CNG recycling loading device according to claim 1, characterized in that, The heating system (21) includes a heater (211) and a switching valve (212), the switching valve (212) being able to control the current flow between the expansion generator (222) and the heater (211).
7. The CNG recycling loading device according to claim 6, characterized in that, The heating system (21) further includes an energy storage device (213). The switching valve (212) includes a first position, a second position, a third position, and a fourth position. In the first position, the expansion generator (222) and the heater (211) are connected in series. In the second position, the expansion generator (222) and the energy storage device (213) are connected in series. In the third position, the energy storage device (213) and the heater (211) are connected in series. In the fourth position, the expansion generator (222), the heater (211), and the energy storage device (213) are disconnected from each other.
8. The CNG recycling loading device according to claim 6, characterized in that, The heater (211) is an electromagnetic heater (211).
9. The CNG recycling loading device according to claim 6, characterized in that, The heating system (21) also includes a temperature sensor for monitoring the natural gas temperature at the inlet of the pressure reducing module (1).
10. The CNG recycling loading device according to any one of claims 1-9, characterized in that, The preheating module also includes a filter assembly (24). The pipeline between the heating system (21) and the pressure reducing module (1) is connected to the air inlet of the filter assembly (24). The air inlet of the residual pressure power generation system (22) is connected to the air outlet of the filter assembly (24).