A natural gas overpressure driving-pumped storage coupling power generation system

Abstract

A kind of natural gas overpressure drive-pumped storage coupling power generation system, the input end of natural gas overpressure drive device is connected with high-pressure liquefied natural gas delivery pipeline, for converting the pressure of natural gas into mechanical energy, natural gas overpressure drive device drives mechanical pump to operate, the fluid input end of mechanical pump is connected with the circulating outlet pipe of low-level water storage tank through pipeline, fluid output end is connected with the circulating inlet pipe of high-level water storage tank through pipeline, the circulating outlet pipe of high-level water storage tank is connected with the circulating inlet pipe of low-level water storage tank through hydraulic generator unit, the electric energy generated by hydraulic generator unit is input to battery.The utility model discloses realize natural gas overpressure energy to gravitational potential energy, electric energy, heat energy multi-form conversion, improve energy utilization rate.Through high-low water storage tank energy storage and battery buffer, reduce the dependence on traditional peak-shaving power supply, provide stable hot water while generating electricity, reduce comprehensive energy cost, reduce natural gas overpressure throttling loss, reduce carbon emissions.

Description

Technical Field

[0001] This utility model belongs to the field of power generation equipment technology, specifically relating to a natural gas residual pressure driven-pumped storage coupled power generation system. Background Technology

[0002] During the transmission, purification, and pressure regulation of natural gas, untapped residual pressure energy is often generated due to the existence of pressure gradients. For example, in the transmission stage, natural gas typically needs to be transported over long distances through pipelines under high pressure to ensure transmission efficiency and stability; the pressure inside the pipelines can often reach tens of megapascals. When the natural gas arrives at the purification plant or distribution station and enters the purification stage, the pressure needs to be adjusted to a suitable range to meet the operational requirements of purification processes such as desulfurization, decarbonization, and dehydration, thus creating the first significant pressure drop. In the pressure regulation stage, whether supplying gas to the city gas network or delivering natural gas to industrial and residential users, the pressure must be further reduced to a lower level according to the actual energy demand of downstream users. For example, the pressure in the city pipeline network is usually between 0.4 and 4 megapascals, while the pressure at residential users is as low as around 2000 megapascals, creating an even larger pressure gradient in this process.

[0003] The residual pressure energy generated by the pressure gradient, if directly released through a throttling valve using traditional methods, would not only be a huge waste of energy but also bring a series of additional problems. From the perspective of energy loss, during the throttling process, the pressure energy of high-pressure natural gas is converted into heat energy, most of which is directly dissipated into the air and cannot be effectively utilized. Over the long term, the accumulated energy loss is considerable. From the perspective of equipment operation, the throttling valve is subjected to severe scouring and wear from high-speed airflow during frequent high-pressure releases. This not only shortens the service life of the throttling valve but may also lead to a decrease in valve sealing performance, increasing the risk of natural gas leakage and posing a threat to safe production and environmental protection.

[0004] With the continuous innovation and development of energy technology, the emergence of expander technology has provided an efficient and feasible solution for the secondary utilization of natural gas waste energy, successfully breaking the energy waste dilemma of traditional energy-saving methods. However, existing waste energy utilization technologies are mainly concentrated in the single power generation stage, lacking integration and synergy with energy storage technologies, resulting in low utilization efficiency of waste energy. Utility Model Content

[0005] The technical problem to be solved by this utility model is to overcome the shortcomings of the prior art and provide a natural gas residual pressure driven-pumped hydro storage coupled power generation system that makes full use of the residual pressure energy generated during the natural gas transportation, purification and pressure regulation process, reduces energy waste, and realizes efficient energy conversion and storage.

[0006] The technical solution adopted to solve the above-mentioned technical problems is: a natural gas residual pressure driven-pumped storage coupled power generation system. The input end of the natural gas residual pressure drive device is connected to a high-pressure liquefied natural gas transmission pipeline to convert the pressure of natural gas into mechanical energy. The natural gas residual pressure drive device drives a mechanical pump to operate. The fluid input end of the mechanical pump is connected to the circulating water outlet pipe of the low-level water storage tank through a pipeline, and the fluid output end is connected to the circulating water inlet pipe of the high-level water storage tank through a pipeline. The circulating water outlet pipe of the high-level water storage tank is connected to the circulating water inlet pipe of the low-level water storage tank through a water turbine generator set. The electrical energy generated by the water turbine generator set is input into the battery.

[0007] As a preferred technical solution, the natural gas residual pressure drive device includes a twin-screw compressor expander, a clutch, a first gearbox, and a transfer case. The twin-screw compressor expander is connected to a high-pressure liquefied natural gas transmission pipeline and a low-pressure natural gas output pipeline. The power output shaft of the twin-screw compressor expander is connected to the input shaft of the first gearbox through the clutch. The output shaft of the first gearbox is connected to the first generator and the mechanical pump through the transfer case.

[0008] As a preferred technical solution, it also includes a first generator, the drive shaft of which is connected to a transfer case, and the electrical energy generated by the first generator is input into the battery.

[0009] As a preferred technical solution, a first electric heater is installed in the low-level water storage tank, and a second electric heater is installed in the high-level water storage tank. The first generator supplies power to the first and second electric heaters. Both the low-level and high-level water storage tanks are connected to a water supply pipe and a hot water output pipe.

[0010] As a preferred technical solution, a turbine control valve is installed on the pipeline between the circulating water outlet pipe of the high-level water storage tank and the turbine generator set.

[0011] As a preferred technical solution, a natural gas control valve is provided between the input end of the natural gas residual pressure drive device and the high-pressure liquefied natural gas transmission pipeline.

[0012] As a preferred technical solution, the hydro-generator set includes a hydro-turbine unit, a second gearbox, and a second generator, with the output shaft of the hydro-turbine unit connected to the input shaft of the second generator via the second gearbox.

[0013] The beneficial effects of this utility model are as follows:

[0014] This invention enables the conversion of natural gas surplus pressure energy into gravitational potential energy, electrical energy, and thermal energy, thereby improving energy utilization efficiency. Through high and low-level water storage tanks and battery buffering, it balances grid load, reduces reliance on traditional peak-shaving power sources, provides stable hot water while generating electricity, meets energy needs in various scenarios, reduces overall energy costs, minimizes natural gas surplus pressure loss, reduces fossil fuel consumption, and reduces carbon emissions, exhibiting environmentally friendly and energy-saving characteristics. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the structure of this utility model.

[0016] The components include: 1. Natural gas control valve; 2. Twin-screw expander; 3. Clutch; 4. First gearbox; 5. Transfer case; 6. First generator; 7. Mechanical pump; 8. Turbine unit; 9. Second gearbox; 10. Second generator; 11. Battery; 12. High-level water tank; 13. First electric heater; 14. Turbine control valve; 15. Low-level water tank; and 16. Second electric heater. Detailed Implementation

[0017] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments, but the present invention is not limited to the following embodiments.

[0018] exist Figure 1 In this embodiment, the natural gas residual pressure driven-pumped storage coupled power generation system includes a high-pressure liquefied natural gas transmission pipe, a natural gas control valve 1, a natural gas residual pressure drive device, a mechanical pump 7, a low-level water storage tank 15, a high-level water storage tank 12, a hydro-generator set, and a battery 11.

[0019] The natural gas residual pressure drive unit includes a twin-screw compressor expander 2, a clutch 3, a first gearbox 4, and a transfer case 5. The twin-screw compressor expander 2 is connected to a high-pressure liquefied natural gas transmission pipeline and a low-pressure natural gas output pipeline via a natural gas control valve 1. The power output shaft of the twin-screw compressor expander 2 is connected to the input shaft of the first gearbox 4 via the clutch 3. The output shaft of the first gearbox 4 is connected to a first generator 6 and a mechanical pump 7 via the transfer case 5. The electrical energy generated by the first generator 6 is input to the battery 11. High-pressure natural gas is drawn from a high-pressure liquefied natural gas pipeline. The intake volume is precisely adjusted by a control valve to stabilize the natural gas pressure at the appropriate working pressure of the twin-screw compressor expander 2. The high-pressure natural gas then enters the twin-screw compressor expander 2, where it undergoes depressurization, cooling, and expansion, driving the twin-screw rotor to rotate at high speed. This converts the pressure energy of the natural gas into the mechanical energy of the main shaft of the twin-screw compressor expander 2. The clutch 3 engages or disengages according to the working conditions. The first gearbox 4 adjusts the main shaft speed to match the rated working speed of the water pump and generator. The speed-adjusted power is then transmitted to the transfer case 5, which distributes the power to the drive shaft of the mechanical pump 7 and the drive shaft of the first generator 6 according to a preset ratio.

[0020] The fluid input end of the mechanical pump 7 is connected to the circulating water outlet pipe of the low-level water storage tank 15 through a pipe, and the fluid output end is connected to the circulating water inlet pipe of the high-level water storage tank 12 through a pipe. The high-level water storage tank 12 is equipped with a first electric heater 13, and the low-level water storage tank 15 is equipped with a second electric heater 16. The first generator 6 supplies power to the first electric heater 13 and the second electric heater 16. Both the low-level water storage tank 15 and the high-level water storage tank 12 are connected to a water supply pipe and a hot water output pipe.

[0021] The circulating water outlet pipe of the high-level water tank 12 is connected to the circulating water inlet pipe of the low-level water tank 15 through the hydro-generator set. A turbine control valve 14 is installed on the pipe between the circulating water outlet pipe of the high-level water tank 12 and the hydro-generator set. The electrical energy generated by the hydro-generator set is input to the battery 11. The hydro-generator set includes a turbine unit 8, a second gearbox 9, and a second generator 10. The output shaft of the turbine unit 8 is connected to the input shaft of the second generator 10 through the second gearbox 9.

[0022] During periods of low electricity demand, the focus is on energy storage and heating. Clutch 3 is coupled, and the power distributed by transfer case 5 drives the main shaft of mechanical pump 7 to rotate. Mechanical pump 7 draws water from low-level water tank 15 and pressurizes the water to high-level water tank 12. When the water level in low-level water tank 15 is insufficient, water is replenished through the water supply pipeline. Taking advantage of the natural height difference of the gas field station, the high-level water tank is usually about 100 meters higher than the low-level water tank to maximize the storage of gravitational potential energy and complete the conversion of residual pressure energy to mechanical energy to gravitational potential energy. The gravitational potential energy is temporarily stored in the form of water in high-level water tank 12.

[0023] The other power source allocated by transfer case 5 drives the main shaft of the first generator 6 to rotate. The first generator 6 generates electricity, which is distributed according to the following priority: it is first supplied to the first electric heater 13 in the high-level water tank and the second electric heater 16 in the low-level water tank 15, maintaining the water temperature in both tanks at a stable 55°C. This temperature is suitable for the needs of heat users, such as domestic heating and production heat tracing at the station. The remaining electrical energy is stored in the battery 11 or directly supplied to low-load electricity users at the gas field station to avoid energy waste.

[0024] When the power grid or gas field station enters peak electricity demand, the focus shifts to power generation to supplement the grid. Clutch 3 disengages, switching to energy release and power generation mode. The turbine control valve 14 is opened, and the valve opening is adjusted according to the electricity load demand. The hot water in the high-level hot water storage tank is controlled to impact the turbine impeller at a stable flow rate. The gravitational potential energy and kinetic energy of the hot water drive the turbine impeller to rotate at high speed, transferring energy to the turbine main shaft. The turbine main shaft is connected to the second gearbox 9, which, after speed regulation, drives the main shaft of the second generator 10 to rotate. The second generator 10 converts mechanical energy into electrical energy, directly supplying peak-demand users, such as station production equipment and grid supplementation. At the same time, the battery 11 is triggered to discharge, releasing the electrical energy stored during off-peak periods. This energy, along with the electrical energy from the second generator 10, supplements the peak load of the power grid, ensuring power supply stability. The hot water after driving the turbine to perform work flows back to the low-level water storage tank 15 through pipelines, completing the water circulation and preparing for the next pumping and energy storage cycle.

Claims

1. A natural gas residual pressure driven pumped-storage coupled power generation system, characterized in that, The input end of the natural gas residual pressure drive device is connected to the high-pressure liquefied natural gas transmission pipeline to convert the pressure of natural gas into mechanical energy. The natural gas residual pressure drive device drives the mechanical pump (7) to run. The fluid input end of the mechanical pump (7) is connected to the circulating water outlet pipe of the low-level water storage tank (15) through a pipeline, and the fluid output end is connected to the circulating water inlet pipe of the high-level water storage tank (12) through a pipeline. The circulating water outlet pipe of the high-level water storage tank (12) is connected to the circulating water inlet pipe of the low-level water storage tank (15) through a water turbine generator set. The electrical energy generated by the water turbine generator set is input to the battery (11).

2. The natural gas residual pressure driven-pumped hydro storage coupled power generation system according to claim 1, characterized in that, The natural gas residual pressure drive device includes a twin-screw compressor expander (2), a clutch (3), a first gearbox (4), and a transfer case (5). The twin-screw compressor expander (2) is connected to a high-pressure liquefied natural gas pipeline and a low-pressure natural gas output pipe. The power output shaft of the twin-screw compressor expander (2) is connected to the input shaft of the first gearbox (4) through the clutch (3). The output shaft of the first gearbox (4) is connected to the first generator (6) and the mechanical pump (7) through the transfer case (5).

3. The natural gas residual pressure driven-pumped hydro storage coupled power generation system according to claim 2, characterized in that, It also includes a first generator (6), whose drive shaft is connected to the transfer case (5), and the electrical energy generated by the first generator (6) is input into the battery (11).

4. The natural gas residual pressure driven-pumped hydro storage coupled power generation system according to claim 3, characterized in that, The low-level water storage tank (15) is equipped with a second electric heater (16), and the high-level water storage tank (12) is equipped with a first electric heater (13). The first generator (6) supplies power to the first electric heater (13) and the second electric heater (16). The low-level water storage tank (15) and the high-level water storage tank (12) are both connected to a water supply pipe and a hot water output pipe.

5. The natural gas residual pressure driven-pumped hydro storage coupled power generation system according to claim 1, characterized in that, A turbine control valve (14) is installed on the pipeline between the circulating water outlet pipe of the high-level water storage tank (12) and the turbine generator set.

6. The natural gas residual pressure driven-pumped hydro storage coupled power generation system according to claim 1, characterized in that, A natural gas control valve (1) is provided between the input end of the natural gas residual pressure drive device and the high-pressure liquefied natural gas transmission pipeline.

7. The natural gas residual pressure driven-pumped hydro storage coupled power generation system according to claim 1, characterized in that, The hydro-generator set includes a turbine unit (8), a second gearbox (9), and a second generator (10). The output shaft of the turbine unit (8) is connected to the input shaft of the second generator (10) through the second gearbox (9).

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