Natural gas excess pressure differential pressure power generation device

Abstract

The utility model belongs to the technical field of differential pressure energy utilization, and relates to a natural gas excess pressure differential pressure power generation device which comprises an upstream gas supply pipe network, a header pipe pressure reducing valve, a downstream gas supply pipe network, an expansion machine, a power generator and a power distribution unit. The upstream air supply pipe network is communicated with the downstream air supply pipe network through a main pipe pressure reducing valve; one end of the expansion machine is communicated with a pipeline between an upstream air supply pipe network and a main pipe pressure reducing valve; the other end of the expansion machine is communicated with a pipeline between a main pipe pressure reducing valve and a downstream air supply pipe network; and the power distribution unit is connected with the expansion machine through the generator. According to the utility model, differential pressure energy is recovered and converted into mechanical energy, so that energy waste is avoided, and secondary utilization of energy is realized.

Description

Technical Field

[0001] The utility model belongs to the technical field of differential pressure energy utilization and relates to a natural gas residual pressure differential power generation device. Background Art

[0002] At present, high-pressure gas transmission is mainly adopted for domestic long-distance natural gas pipelines. The gas transmission pressure of long-distance natural gas pipelines can generally reach 10 MPa. After natural gas is extracted from each gas field, it is transported (upstream) to cities or user ends (downstream) through long-distance pipelines. In order to adapt to the operation of urban gas pipelines at all levels and the needs of users, it is necessary to reduce the pressure of natural gas from high pressure (such as the design pressure of the long-distance pipeline is 10 MPa) to a lower pressure at gas pressure regulating stations at all levels in the city; in the conventional transportation process, the pressure reduction of natural gas is achieved through pressure regulating devices such as large pressure reducing valves. A very rich amount of pressure energy is contained in the process of natural gas pressure reduction. Calculated by adjusting the upstream pressure from 8.0 MPa to the downstream pressure of 0.4 MPa, 6 billion kWh of electric energy can be recovered annually. Since the differential pressure energy is irreversible in the pressure-reducing transportation, a large amount of differential pressure energy is wasted. At the same time, serious pipeline vibration, noise and other problems will also occur during the natural gas pressure regulation process.

[0003] At present, when LNG gasification stations reduce the pressure of natural gas, a Joule-Thomson throttle expansion valve (J-T valve) is used for throttling to reduce energy waste. However, when the pressure difference between the upstream pipe network and the downstream pipe network is large and during natural gas peak shaving, serious waste of pressure energy will still be caused by throttling, which does not meet the development requirements of natural gas carbon reduction and emission reduction. Content of the Utility Model

[0004] Aiming at the technical problem of differential pressure energy waste existing in the existing natural gas pressure reduction process, the utility model provides a natural gas residual pressure differential power generation device.

[0005] In the utility model, by setting an upstream gas supply pipe network, a main pipe pressure reducing valve, a downstream gas supply pipe network, an expander, a generator and a power distribution unit, the differential pressure energy is recovered and converted into mechanical energy, avoiding energy waste and realizing secondary utilization of energy.

[0006] In order to achieve the above purpose, the technical scheme adopted by the utility model is:

[0007] A natural gas residual pressure differential power generation device includes an upstream gas supply pipe network, a main pipe pressure reducing valve, a downstream gas supply pipe network, an expander, a generator and a power distribution unit;

[0008] The upstream gas supply pipeline is connected to the downstream gas supply pipeline through a main pipeline pressure reducing valve; one end of the expander is connected to the pipeline between the upstream gas supply pipeline and the main pipeline pressure reducing valve; the other end of the expander is connected to the pipeline between the main pipeline pressure reducing valve and the downstream gas supply pipeline; the power distribution unit is connected to the expander through a generator.

[0009] Further defined, the natural gas residual pressure differential power generation device further includes a main gas supply pipeline; the upstream gas supply pipeline is connected to the downstream gas supply pipeline through the main gas supply pipeline; the main pipeline pressure reducing valve is located on the main gas supply pipeline; both ends of the expander are correspondingly connected into the main gas supply pipeline at both ends of the main pipeline pressure reducing valve.

[0010] Further defined, an inlet connecting pipe and an outlet connecting pipe are sequentially arranged on the main gas supply pipeline along the gas supply direction, and the main pipeline pressure reducing valve is located between the inlet connecting pipe and the outlet connecting pipe; one end of the expander is connected into the main gas supply pipeline through the inlet connecting pipe; the other end of the expander is connected into the main gas supply pipeline through the outlet connecting pipe.

[0011] Further defined, an inlet control valve and an inlet interlock valve are sequentially arranged on the inlet connecting pipe; the inlet interlock valve is arranged close to the expander.

[0012] Further defined, the natural gas residual pressure differential power generation device further includes a branch gas supply pipeline; one end of the branch gas supply pipeline is connected to the inlet connecting pipe, the other end of the branch gas supply pipeline is connected to the outlet connecting pipe, and the branch gas supply pipeline is located between the inlet control valve and the inlet interlock valve.

[0013] Further defined, the natural gas residual pressure differential power generation device further includes a bypass gas supply pipeline; one end of the bypass gas supply pipeline is connected to the inlet connecting pipe, the other end of the bypass gas supply pipeline is connected to the outlet connecting pipe, and the bypass gas supply pipeline is located between the branch gas supply pipeline and the inlet interlock valve.

[0014] Further defined, a branch pipeline control valve is arranged on the branch gas supply pipeline; a bypass interlock valve and a bypass control valve are sequentially arranged on the bypass gas supply pipeline along the gas supply direction.

[0015] Further defined, the natural gas residual pressure differential power generation device further includes a DCS control system, and the DCS control system is respectively connected to the main pipeline pressure reducing valve, the inlet control valve, the inlet interlock valve, the branch pipeline control valve, the bypass interlock valve and the bypass control valve.

[0016] Compared with the prior art, the beneficial effects of the present utility model are:

[0017] 1. The utility model is provided with an upstream gas supply pipeline network, a main pipeline pressure reducing valve, a downstream gas supply pipeline network, an expander, a generator and a power distribution unit. The expander and the generator are used to convert the pressure difference energy generated by the gasification of natural gas into mechanical energy and apply it to the power generation system, thereby avoiding energy waste, realizing the recovery and secondary utilization of the pressure difference energy, and achieving the reduction of carbon emissions of natural gas.

[0018] 2. In the utility model, an upstream gas supply pipeline network, a main pipeline pressure reducing valve, a downstream gas supply pipeline network and an expander are provided, and the expander is in parallel with the main pipeline pressure reducing valve, with one in use and one in reserve, greatly improving the reliability and safety of the pressure difference power generation device.

[0019] 3. In the utility model, by setting the main pipeline pressure reducing valve, the inlet control valve and the inlet interlock valve, the flow rates of the natural gas entering the downstream gas supply pipeline network and the expander are controlled respectively, realizing the smooth switching of the device and ensuring safe operation.

[0020] 4. In the utility model, by setting the gas supply branch pipeline and the gas supply bypass pipeline, when the LNG production makes an emergency stop, the natural gas can pass through the gas supply branch pipeline and the gas supply bypass pipeline, ensuring the safety and stable operation of the whole system.

[0021] 5. The pressure difference power generation device provided by the utility model utilizes the pressure difference energy generated during the production or transportation of natural gas, recovers and converts it into mechanical energy, drives the generator to generate electricity, realizes the secondary energy recovery, and achieves the purpose of energy conservation and carbon reduction. The whole device not only has a simple structure, low cost, but also operates stably and reliably. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Schematic diagram of the first natural gas residual pressure difference power generation device provided for Embodiment 1;

[0023] Figure 2 Schematic diagram of the natural gas residual pressure difference power generation device provided for Embodiment 2;

[0024] Among them:

[0025] 1 - upstream gas supply pipeline network; 2 - main gas supply pipeline; 3 - main pipeline pressure reducing valve; 4 - downstream gas supply pipeline network; 5 - gas supply branch pipeline; 6 - inlet control valve; 7 - branch pipeline regulating valve; 8 - gas supply bypass pipeline; 9 - bypass interlock valve; 10 - bypass regulating valve; 11 - inlet interlock valve; 12 - expander; 13 - generator; 14 - power distribution unit; 15 - inlet connecting pipe; 16 - outlet connecting pipe. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0026] The following elaborates on the preferred embodiments of the utility model in conjunction with the drawings, so that the advantages and features of the utility model can be more easily understood by those skilled in the art, thereby making a clearer and more definite definition of the protection scope of the utility model.

[0027] Example 1

[0028] Refer to Figure 1 , the natural gas residual pressure differential power generation device provided in this embodiment includes an upstream gas supply network 1, a main pipe pressure reducing valve 3, a downstream gas supply network 4, an expander 12, a generator 13, and a power distribution unit 14; the upstream gas supply network 1 is connected to the downstream gas supply network 4 through the main pipe pressure reducing valve 3; the upstream gas supply network 1 is connected to the downstream gas supply network 4 through the main pipe pressure reducing valve 3; one end of the expander 12 is connected to the pipeline between the upstream gas supply network 1 and the main pipe pressure reducing valve 3; the other end of the expander 12 is connected to the pipeline between the main pipe pressure reducing valve 3 and the downstream gas supply network 4; the power distribution unit 14 is connected to the expander 12 through the generator 13.

[0029] In this embodiment, the high-pressure natural gas in the upstream gas supply network 1 is reduced to low pressure by the main pipe pressure reducing valve 3 and then directly enters the downstream gas supply network 4. During the pressure-reducing transportation of natural gas, differential pressure energy will be released due to pressure reduction. The differential pressure energy is introduced into the expander 12, and the differential pressure energy is converted into mechanical energy by the expander 12 and does work on the generator 13 to generate electricity. Then, the mechanical energy is converted into electrical energy to provide power distribution for the power distribution unit 14, realizing the recovery, conversion, and secondary utilization of differential pressure energy, thereby avoiding energy waste and achieving the purpose of energy conservation and carbon reduction.

[0030] In this embodiment, to facilitate the connection of the upstream gas supply network 1, the main pipe pressure reducing valve 3, and the downstream gas supply network 4, the natural gas residual pressure differential power generation device further includes a main gas supply pipeline 2; the main pipe pressure reducing valve 3 is located on the main gas supply pipeline 2, and the upstream gas supply network 1 is connected to the downstream gas supply network 4 through the main gas supply pipeline 2; then, both ends of the expander 12 are correspondingly connected into the main gas supply pipeline 2 at both ends of the main pipe pressure reducing valve 3. That is, the inlet end of the expander 12 is connected to the main gas supply pipeline 2 between the upstream gas supply network 1 and the main pipe pressure reducing valve 3, and the outlet end of the expander 12 is connected to the main gas supply pipeline 2 between the main pipe pressure reducing valve 3 and the downstream gas supply network 4; so that the expander 12 and the main pipe pressure reducing valve 3 are in parallel, one for use and one for standby, greatly improving the reliability and safety of the differential pressure power generation device.

[0031] In this embodiment, an inlet connection pipe 15 and an outlet connection pipe 16 are arranged in sequence along the gas supply direction on the main gas supply pipeline 2; one end of the expander 12 is connected into the main gas supply pipeline 2 through the inlet connection pipe 15; the other end of the expander 12 is connected into the main gas supply pipeline 2 through the outlet connection pipe 16. The main pipe pressure reducing valve 3 is located between the inlet connection pipe 15 and the outlet connection pipe 16.

[0032] During implementation, the connection between the main gas supply pipeline 2 and the inlet end of the expander 12 is realized through the inlet connection pipe 15, and the connection between the main gas supply pipeline 2 and the outlet end of the expander 12 is realized through the outlet connection pipe 16, improving the fast and stable connection between devices.

[0033] In this embodiment, an inlet control valve 6 and an inlet interlock valve 11 are sequentially arranged on the inlet connecting pipe 15 ; the inlet interlock valve 11 is arranged close to the expander 12 .

[0034] In this embodiment, the inlet control valve 6, the inlet interlock valve 11 and the main pipe pressure reducing valve 3 are used in combination. When the main pipe pressure reducing valve 3 is opened, the inlet control valve 6 and the inlet interlock valve 11 are closed, and the natural gas gasified in the upstream gas supply network 1 is decompressed by the main pipe pressure reducing valve 3 and then transported to the downstream gas supply network 4; when the main pipe pressure reducing valve 3 is closed, the inlet control valve 6 and the inlet interlock valve 11 are both opened, and the natural gas gasified in the upstream gas supply network 1 is transported to the expander 12 through the inlet connecting pipe 15, and a part of the natural gas is directly transported to the downstream gas supply network 4 after being stabilized by the outlet connecting pipe 16, and a part of the natural gas is converted into mechanical energy through expansion work to drive the generator 13 to generate electricity. In addition, when the equipment is overhauled, by reducing the valve opening of the inlet interlock valve 11 and increasing the valve opening of the main pipe pressure reducing valve 3, the smooth switching of the natural gas is achieved to ensure the safe operation of the device.

[0035] In this embodiment, the output power of the generator 13 is 800KW, and the expander 12 is a turbine expander, a twin-screw expander, a single-rotor expander or a twin-rotor expander. Preferably, the expander 12 is a turbine expander, which mainly uses high-pressure airflow to impact the impeller to achieve energy conversion, has the characteristics of high speed and high isentropic efficiency, and is suitable for working conditions with large flow rate and stable pressure.

[0036] Example 2

[0037] See also Figure 2 On the basis of Example 1, the natural gas residual pressure differential power generation device provided in this embodiment also includes a gas supply branch pipeline 5; one end of the gas supply branch pipeline 5 is connected to the inlet connecting pipe 15, and the other end of the gas supply branch pipeline 5 is connected to the outlet connecting pipe 16, and the gas supply branch pipeline 5 is located between the inlet control valve 6 and the inlet interlock valve 11.

[0038] In order to facilitate the conduction and closing of the gas supply branch pipeline 5, a branch regulating valve 7 is arranged on the gas supply branch pipeline 5; when the distribution unit 14 stops in an emergency, the inlet interlock valve 11 is closed in an emergency to cut off the natural gas from entering the expander 12. After the natural gas passes through the inlet control valve 6, the branch regulating valve 7 is opened, and the natural gas is introduced into the outlet connecting pipe 16 through the gas supply branch pipeline 5 and then enters the downstream gas supply network 4 after stabilizing the pressure, so that the natural gas passes through the bypass to ensure the safe and stable operation of the entire system.

[0039] In this embodiment, the natural gas residual pressure differential power generation device further includes a gas supply bypass pipeline 8. One end of the gas supply bypass pipeline 8 is communicated with the inlet connecting pipe 15, and the other end of the gas supply bypass pipeline 8 is communicated with the outlet connecting pipe 16. The gas supply bypass pipeline 8 is located between the gas supply branch pipeline 5 and the inlet interlocking valve 11. A bypass interlocking valve 9 and a bypass regulating valve 10 are sequentially arranged on the gas supply bypass pipeline 8 along the gas supply direction, which is convenient for cutting off and conducting the gas supply bypass pipeline 8, and forming an interlock with other valves for convenient control.

[0040] During implementation, the gas supply bypass pipeline 8 and the gas supply branch pipeline 5 are two bypasses, one for standby and the other for use, which is flexible and convenient to use.

[0041] In the present utility model, in order to facilitate the control of each valve, the natural gas residual pressure differential power generation device further includes a DCS control system. The DCS control system is respectively connected to the main pipeline pressure reducing valve 3, the inlet control valve 6, the inlet interlocking valve 11, the branch pipe regulating valve 7, the bypass interlocking valve 9 and the bypass regulating valve 10. By connecting the corresponding valves to the DCS system, automatic variable load operation is realized according to the gas supply volume.

[0042] The above are only the embodiments of the present utility model, and do not limit the protection scope of the patent of the present utility model. Any equivalent structure or equivalent process transformation made by using the description and drawings of the present utility model, or directly or indirectly applied to other related technical fields, shall be equally included in the protection scope of the present utility model.

Claims

1. A natural gas residual pressure differential power generation device, characterized in that: It comprises an upstream gas supply network (1), a main pipe pressure reducing valve (3), a downstream gas supply network (4), an expander (12), a generator (13) and a power distribution unit (14); The upstream gas supply network (1) is connected to the downstream gas supply network (4) via the main pipe pressure reducing valve (3); one end of the expander (12) is connected to the pipeline between the upstream gas supply network (1) and the main pipe pressure reducing valve (3); the other end of the expander (12) is connected to the pipeline between the main pipe pressure reducing valve (3) and the downstream gas supply network (4); and the power distribution unit (14) is connected to the expander (12) via the generator (13).

2. The natural gas residual pressure differential power generation device according to claim 1, characterized in that: The natural gas residual pressure differential power generation device also includes a main gas supply pipeline (2); the upstream gas supply pipeline network (1) is connected to the downstream gas supply pipeline network (4) via the main gas supply pipeline (2); the main pipeline pressure reducing valve (3) is located on the main gas supply pipeline (2); and the two ends of the expander (12) are correspondingly connected to the main gas supply pipeline (2) at the two ends of the main pipeline pressure reducing valve (3).

3. The natural gas residual pressure differential power generation device according to claim 2, characterized in that: An inlet connecting pipe (15) and an outlet connecting pipe (16) are arranged in sequence on the gas supply main pipeline (2) along the gas supply direction, and the main pipeline pressure reducing valve (3) is located between the inlet connecting pipe (15) and the outlet connecting pipe (16); one end of the expander (12) is connected to the gas supply main pipeline (2) through the inlet connecting pipe (15); and the other end of the expander (12) is connected to the gas supply main pipeline (2) through the outlet connecting pipe (16).

4. The natural gas residual pressure differential power generation device according to claim 3, characterized in that: An inlet control valve (6) and an inlet interlock valve (11) are arranged in sequence on the inlet connecting pipe (15); the inlet interlock valve (11) is arranged close to the expander (12).

5. The natural gas residual pressure differential power generation device according to claim 4, characterized in that: The natural gas residual pressure differential power generation device also includes a gas supply branch pipeline (5); one end of the gas supply branch pipeline (5) is connected to the inlet connecting pipe (15), and the other end of the gas supply branch pipeline (5) is connected to the outlet connecting pipe (16); the gas supply branch pipeline (5) is located between the inlet control valve (6) and the inlet interlock valve (11).

6. The natural gas residual pressure differential power generation device according to claim 5, characterized in that: The natural gas residual pressure differential power generation device also includes a gas supply bypass pipeline (8); one end of the gas supply bypass pipeline (8) is connected to the inlet connecting pipe (15), and the other end of the gas supply bypass pipeline (8) is connected to the outlet connecting pipe (16); the gas supply bypass pipeline (8) is located between the gas supply branch pipeline (5) and the inlet interlock valve (11).

7. The natural gas residual pressure differential power generation device according to claim 6, characterized in that: The gas supply branch pipeline (5) is provided with a branch pipe regulating valve (7); the gas supply bypass pipeline (8) is provided with a bypass interlocking valve (9) and a bypass regulating valve (10) in sequence along the gas supply direction.

8. The natural gas residual pressure differential power generation device according to any one of claims 4 to 7, characterized in that: The natural gas residual pressure differential power generation device also includes a DCS control system, which is respectively connected to the main pipe pressure reducing valve (3), the inlet control valve (6), the inlet interlock valve (11), the branch pipe regulating valve (7), the bypass interlock valve (9) and the bypass regulating valve (10).

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