A combined system for power generation and ice making using natural gas residual pressure

Abstract

This invention discloses a combined natural gas pressure relief power generation and ice-making system, relating to the technical field of natural gas pressure regulating equipment. It includes a pre-cooling chamber, a pressure regulating power generation device, an ice-making device, and a circulation pipeline. The pre-cooling chamber is located between the upstream natural gas outlet and the pressure regulating power generation device. The pressure regulating power generation device is connected to the upstream natural gas outlet via a high-pressure gas supply pipeline passing through the pre-cooling chamber. The outlet of the pre-cooling chamber connects to the downstream natural gas inlet. The ice-making device includes a first heat exchanger and a second heat exchanger, and the pressure regulating power generation device is connected to both the first and second heat exchangers. One end of the circulation pipeline is connected to the ice-making device, and the other end connects to the inlet of the pre-cooling chamber. This invention recirculates the natural gas, after pressure relief power generation and cold energy ice-making, back to the pre-cooling chamber to pre-cool the upstream natural gas. Simultaneously, the natural gas after cold energy utilization absorbs heat from the upstream natural gas to reach a temperature close to the downstream natural gas's operating temperature, achieving full utilization of energy before and after natural gas pressure regulation.

Description

Technical Field

[0001] This invention relates to the field of natural gas pressure regulating equipment technology, and in particular to a combined system for generating electricity and making ice using natural gas residual pressure. Background Technology

[0002] Natural gas is a highly efficient and clean energy source. Due to its high calorific value, large reserves, ease of transmission and distribution, and low pollutant emissions from combustion, its share in the energy structure of various countries is increasing daily. However, the natural gas resource and demand markets are largely unevenly distributed geographically. To address this, most countries worldwide have adopted the method of laying natural gas pipelines, with high pressure and large diameter being the current general trend in natural gas pipeline development. Before being delivered to downstream users, high-pressure natural gas must undergo appropriate pressure reduction at pressure regulating stations, gas stations, and natural gas receiving gate stations in various cities to ensure the normal and safe operation of ordinary gas users downstream. Natural gas experiences a significant pressure drop before and after pressure regulation at the gate station. Under the Joule-Thomson effect, the natural gas temperature drops sharply, and a large amount of cold energy is released after pressure reduction. Pressure regulating stations typically use throttle valves and other pressure regulating devices to directly reduce the pressure of natural gas. This pressure energy is entirely consumed in overcoming flow resistance without driving any mechanical work, resulting in energy waste.

[0003] Chinese patent application CN201910486649.1 discloses a natural gas pressure regulating station residual pressure comprehensive utilization system, including: a natural gas pressure regulating device, a power generation device, and a cold storage refrigeration device; the natural gas pressure regulating device includes a prime mover, a first condenser, and a temperature regulator; the power generation device includes a generator, the prime mover is coaxially connected to the generator, and the generator is connected to an external power grid; the cold storage refrigeration device includes a first compressor, a first throttle valve, a cold storage room, and a cold storage supplementary refrigeration device; the cold storage room is equipped with a first evaporator and a second evaporator. This natural gas pressure regulating station residual pressure comprehensive utilization system, in addition to generating electricity using the pressure difference generated during natural gas pressure regulation, also utilizes the residual cooling generated during the natural gas pressure regulation process to cool the cold storage room. However, it only utilizes the cooling capacity after pressure release, and the used natural gas cannot be recycled, resulting in insufficient energy utilization.

[0004] Chinese patent application CN201910486661.2 discloses a combined power generation and ice-making system utilizing natural gas residual pressure, comprising: a first pressure regulating device and a natural gas regulating and ice-making device; the first pressure regulating device includes a first pressure stabilizing valve, a first precooler, a heater, a second pressure stabilizing valve, a first expander, a first generator, and a first heat exchanger; the natural gas regulating and ice-making device includes a first water storage tank, a first compressor, a second compressor, a condenser, a cooling tower, a first throttling valve, a second throttling valve, an evaporator, and an ice maker. This system utilizes the residual pressure and cold energy generated during the pressure regulation process of high-pressure upstream natural gas, enabling the residual pressure to generate electricity and the cold energy to make ice.

[0005] In summary, the energy released during natural gas pressure regulation is enormous, and its non-utilization would result in significant energy waste. Furthermore, the released energy would have a substantial impact on natural gas pressure regulating station equipment and natural gas transmission equipment. However, the current utilization rate of natural gas pressure is low; some residual cold energy remains after power generation and ice making, and its effective utilization has not yet been achieved. Summary of the Invention

[0006] To improve energy utilization, this invention provides a combined natural gas waste pressure power generation and ice-making system to address the current problem of wasted natural gas waste pressure. A pre-cooling chamber is set up between the upstream natural gas outlet and the pressure regulating power generation device. The natural gas, after being depressurized for power generation and used for ice making, is recycled back to the pre-cooling chamber to pre-cool the upstream natural gas. At the same time, the natural gas after cold energy utilization absorbs heat from the upstream natural gas to reach a temperature close to that of the downstream natural gas, achieving full utilization of energy before and after natural gas pressure regulation.

[0007] The technical solution adopted in this invention is:

[0008] A combined natural gas waste pressure power generation and ice-making system includes a precooling chamber, a pressure regulating power generation device, an ice-making device, and a circulation pipeline;

[0009] The precooling chamber is located between the upstream natural gas outlet and the pressure regulating power generation device; the pressure regulating power generation device is connected to the upstream high-pressure natural gas outlet through a high-pressure gas supply pipeline passing through the precooling chamber;

[0010] The outlet of the precooling chamber is connected to the downstream natural gas inlet;

[0011] The ice-making device includes a first heat exchanger and a second heat exchanger, and the voltage regulating power generation device is connected to the first heat exchanger and the second heat exchanger respectively;

[0012] One end of the circulation pipe is connected to the ice-making device, and the other end is connected to the air inlet of the precooling chamber.

[0013] Preferably, the voltage regulating power generation device includes an expander and a generator, the expander being connected to the upstream natural gas outlet through the high-pressure gas supply pipeline, and the expander being connected to the generator.

[0014] Preferably, the expander is further provided with a first air outlet and a second air outlet; the first air outlet is connected to the first heat exchanger, and the second air outlet is connected to the second heat exchanger.

[0015] Preferably, the ice-making device further includes a first water storage tank, an evaporator, a compressor, and an ice maker; one end of the evaporator is connected to a refrigerant input pipe that communicates with the precooling chamber, and the other end is connected to the compressor; the compressor is connected to the second heat exchanger through the air inlet of the second heat exchanger.

[0016] The first heat exchanger is provided with a first heat exchange air outlet and a first heat exchange liquid outlet; the first heat exchange air outlet is connected to the circulation pipe; the first heat exchange liquid outlet is connected to the ice maker.

[0017] The second heat exchanger is provided with a second heat exchange air outlet and a second heat exchange liquid outlet; the second heat exchange air outlet is connected to the circulation pipe; the second heat exchange liquid outlet is connected to the ice maker.

[0018] The first water storage tank is connected to the first heat exchanger.

[0019] Preferably, the ice-making device further includes a second water storage tank, which is connected to the first water storage tank, and the low-pressure natural gas output from the first heat exchange outlet and the second heat exchange outlet passes through the second water storage tank before entering the circulation pipeline.

[0020] Preferably, the precooling chamber includes a first precooling room and a second precooling room; the refrigerant input pipeline is connected to the first precooling room and the ice maker is connected to the first precooling room through a refrigerant liquid return pipeline; the circulation pipeline leads into the second precooling room; the high-pressure natural gas input from the upstream natural gas outlet passes through the first precooling room and the second precooling room in sequence and enters the pressure regulating power generation device through the high-pressure gas supply pipeline.

[0021] Preferably, the air inlet is inclined into the precooling chamber; and the angle between the axis of the air inlet and the inner wall of the precooling chamber is 30-45°.

[0022] Preferably, the inner sidewall of the precooling chamber is spiral-shaped, and the spiral direction is opposite to the airflow direction in the high-pressure gas supply pipeline.

[0023] Preferably, the air inlet is funnel-shaped, and the diameter of the air inlet gradually increases from the end away from the precooling chamber to the end closer to the precooling chamber.

[0024] Preferably, a first pressure regulating valve and a second pressure regulating valve are respectively installed on the high-pressure gas supply pipeline and the circulation pipeline.

[0025] Preferably, the circulation pipeline is also provided with a bypass pipeline connected to the downstream natural gas inlet.

[0026] Preferably, the circulation pipe and the bypass pipe are connected by a three-way valve.

[0027] Compared with the prior art, the beneficial effects of the present invention are:

[0028] This invention addresses the problem of wasted natural gas residual pressure energy by providing a combined natural gas residual pressure power generation and ice-making system. A pre-cooling chamber is set up between the upstream natural gas outlet and the pressure regulating power generation device. The natural gas, after being depressurized for power generation and used for ice making, is circulated back to the pre-cooling chamber through a circulation pipeline to pre-cool the upstream natural gas. At the same time, the natural gas after cold energy utilization absorbs heat from the upstream natural gas to reach a temperature close to that of the downstream natural gas, achieving full utilization of energy before and after natural gas pressure regulation. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of a combined natural gas waste pressure power generation and ice-making system provided by the present invention;

[0030] Figure label:

[0031] 1-Pre-cooling chamber; 2-Voltage regulating generator; 201-Expander; 202-Generator; 203-First pressure regulating valve;

[0032] 3-Ice-making device; 301-First heat exchanger; 302-Second heat exchanger; 303-Evaporator; 304-Compressor;

[0033] 305 - Ice maker; 306 - First water storage tank; 307 - Second water storage tank;

[0034] 4- Circulation pipeline; 401- Second pressure regulating valve; 5- Upstream natural gas outlet; 6- Downstream natural gas inlet;

[0035] 7-High-pressure gas supply pipeline; 8-Bypass pipeline; 9-Refrigerant input pipeline; 10-Refrigerant liquid return pipeline. Detailed Implementation

[0036] To make the objectives and technical solutions of the embodiments of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention.

[0037] In the description of this application, it should be understood that the terms "length", "upper", "lower", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and 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 application.

[0038] like Figure 1As shown, a natural gas waste pressure power generation and ice-making combined system includes a pressure regulating power generation unit 2, an ice-making unit 3, a pre-cooling chamber 1, and a circulation pipeline 4. The pre-cooling chamber 1 is located between the pressure regulating power generation unit 2 and the upstream natural gas outlet 5. The pre-cooling chamber 1 is provided with an inlet and an outlet. The pressure regulating power generation unit 2 is connected to the upstream natural gas outlet 5 through a high-pressure gas supply pipeline 7 passing through the pre-cooling chamber 1. Therefore, the high-pressure natural gas discharged from the upstream natural gas outlet 5 first enters the pre-cooling chamber 1 and then enters the pressure regulating power generation unit 2.

[0039] The voltage regulating power generation device 2 includes an expander 201 and a generator 202. The expander 201 is connected to the precooling chamber 1 via the high-pressure gas supply pipeline 7, and is also connected to the generator 202. High-pressure natural gas discharged from the upstream natural gas outlet 5 enters the expander 201 through the high-pressure gas supply pipeline 7. A first pressure regulating valve 203 is provided on the high-pressure gas supply pipeline 7 to control the flow rate of the high-pressure natural gas in the pipeline 7. The expander 201 is connected to the generator 202 and the ice-making device 3. After passing through the expander 201 and generating electricity, the high-pressure natural gas is converted into low-pressure natural gas and enters the ice-making device 3.

[0040] The ice-making device 3 includes a first heat exchanger 301 and a second heat exchanger 302, and the voltage regulating power generation device 2 is connected to the first heat exchanger 301 and the second heat exchanger 302 respectively. The expander 201 is provided with a first air outlet and a second air outlet; the first air outlet is connected to the first heat exchanger 301, and the second air outlet is connected to the second heat exchanger 302.

[0041] The ice-making device 3 further includes a first water storage tank 306, an evaporator 303, a compressor 304, and an ice maker 305. One end of the evaporator 303 is connected to a refrigerant input pipe 9, which communicates with the pre-cooling chamber 1, and the other end is connected to the compressor 304. The compressor 304 is connected to the second heat exchanger 302 through the air inlet of the second heat exchanger 302. The pre-cooling chamber 1 inputs refrigerant into the evaporator 303 through the refrigerant input pipe 9, and evaporates the refrigerant into refrigerant gas. The evaporator 303 is connected to the compressor 304, which compresses the refrigerant gas into high-pressure refrigerant gas, and enters the second heat exchanger 302 through the air inlet of the second heat exchanger 302 to exchange heat with low-pressure natural gas to obtain low-temperature refrigerant liquid. The second heat exchanger 302 is provided with a second heat exchange gas outlet and a second heat exchange liquid outlet; the second heat exchange gas outlet is connected to the circulation pipe 4, and the low-pressure natural gas after heat exchange enters the circulation pipe 4 and enters the precooler through the gas inlet of the precooler; the second heat exchange liquid outlet is connected to the ice maker 305, and the low-temperature refrigerant liquid generated after heat exchange enters the ice maker 305 for ice making.

[0042] The low-pressure natural gas output from the first outlet of the expander 201 enters the first heat exchanger 301 through the first heat exchange inlet. The first water storage tank 306 is connected to the first heat exchanger 301, and the water in the first water storage tank 306 enters the first heat exchanger 301 and exchanges heat with the low-pressure natural gas in the first heat exchanger 301. The first heat exchanger 301 is provided with a first heat exchange outlet and a first heat exchange liquid outlet. The low-pressure natural gas after heat exchange enters the circulation pipe 4 through the first heat exchange outlet and finally returns to the precooler. The first heat exchange liquid outlet is connected to the ice maker 305, so that the water after heat exchange enters the ice maker 305 to make ice.

[0043] The ice-making device 3 also includes a second water storage tank 307, and the low-pressure natural gas output from both the first heat exchange outlet and the second heat exchange outlet passes through the second water storage tank 307 before entering the circulation pipe 4. The second water storage tank 307 is connected to the first water storage tank 306, and after the water in the second water storage tank 307 is cooled by heat exchange, the water in the second water storage tank 307 is replenished into the first water storage tank 306.

[0044] Low-pressure natural gas output from the first and second heat exchange outlets enters the circulation pipeline 4. A second pressure regulating valve 401 is installed on the circulation pipeline to regulate the flow rate of the natural gas within it. The low-pressure natural gas in the circulation pipeline 4 enters the precooler through its inlet, which is inclined into the precooling chamber 1. The inner wall of the precooling chamber 1 is spiral-shaped, with its spiral direction opposite to the airflow direction in the high-pressure gas supply pipeline 7. The angle between the axis of the inlet and the tangent of the inner wall of the precooling chamber 1 is 30-45°. This causes the low-pressure natural gas to spirally swirl around the outside of the high-pressure gas supply pipeline within the precooling chamber 1, increasing the contact time and convection area between the low-pressure natural gas and the high-pressure gas supply pipeline, thereby improving the heat exchange effect between them. The inlet is a funnel-shaped opening with a diameter that gradually increases from the end furthest from the precooling chamber 1 to the end closest to the precooling chamber 1. This gradually slows down the flow rate of the low-pressure natural gas entering the precooling chamber 1 and further reduces the gas pressure. This increases the heat exchange between the low-pressure natural gas and the high-pressure natural gas in the high-pressure gas supply pipeline 7. The low-pressure natural gas lowers the temperature of the high-pressure natural gas, while the high-pressure natural gas raises the temperature of the low-pressure natural gas, thereby improving the utilization rate of the cold energy of the low-pressure natural gas.

[0045] The precooling chamber 1 includes a first precooling room and a second precooling room. The high-pressure gas supply pipeline 7 passes through the first and second precooling rooms sequentially, meaning that the high-temperature, high-pressure natural gas in the high-pressure gas supply pipeline 7 passes through both precooling rooms in one go. The refrigerant input pipeline 9 connected to the evaporator 303 is connected to the first precooling room. The low-temperature refrigerant is input from the first precooling room into the evaporator 303, and the subsequently obtained low-temperature refrigerant liquid, after passing through the ice maker 305, enters the precooling chamber 1 through the refrigerant liquid return pipeline 10. After exchanging heat with the high-temperature natural gas in the precooling chamber 1, it passes through the evaporator 303 to obtain high-pressure refrigerant gas, allowing the refrigerant to be recycled and improving the utilization of natural gas residual pressure. The low-pressure natural gas returned by the circulation pipeline 4 enters the second precooling room. The outlet of the precooling chamber 1 can be directly connected to the downstream natural gas inlet 6, ensuring the flow of natural gas when power generation and ice making are not required.

[0046] The circulation pipeline 4 is also equipped with a bypass pipeline 8, one end of which is connected to the downstream natural gas inlet 6. The circulation pipeline 4 and the bypass pipeline 8 are connected by a three-way valve. When the temperature difference between the natural gas in the high-pressure gas supply pipe and the low-pressure natural gas in the circulation pipeline 4 does not exceed 15°C, the three-way valve is opened, opening the bypass pipeline 8, so that the low-pressure natural gas does not enter the pre-cooling room through the circulation pipeline 4, but is directly introduced into the downstream natural gas inlet 6.

[0047] The specific working process of the natural gas waste pressure power generation and ice-making combined system provided by this invention is as follows:

[0048] Step 1: The high-temperature and high-pressure natural gas discharged from the upstream natural gas outlet 5 passes through the high-pressure gas supply pipeline 7 and the pre-cooling chamber 1 for preliminary heat exchange before entering the pressure regulating power generation unit 2;

[0049] Step 2: The high-pressure natural gas is expanded to generate electricity. The pressure energy during the natural gas pressure regulation process is converted by the expander 201. While the expander 201 is rotating, it drives the generator 202 to generate electricity. The expanded low-pressure natural gas enters the first heat exchanger 301 and the second heat exchanger 302.

[0050] Step 3: The low-temperature liquid in the first water storage tank 306 enters the first heat exchanger 301. The low-pressure natural gas in the first heat exchanger 301 exchanges heat with the low-temperature liquid. After heat exchange, the low-pressure natural gas enters the circulation pipe 4 through the first heat exchange outlet. After heat exchange, the water enters the ice maker 305 for ice making. Refrigerant is introduced into the evaporator 303 and evaporates to obtain refrigerant gas. The refrigerant gas is compressed into high-pressure refrigerant gas and enters the second heat exchanger 302. After heat exchange, the low-pressure natural gas enters the circulation pipe 4 through the second heat exchange outlet. After heat exchange, the low-temperature refrigerant liquid enters the ice maker 305 for ice making.

[0051] Step 4: The low-pressure natural gas output from the first and second heat exchange outlets enters the precooler through the circulation pipeline 4 and exchanges heat with the high-pressure natural gas in the high-pressure gas supply pipeline 7.

[0052] Step 5: When the temperature difference between the natural gas in the high-pressure gas supply pipe and the low-pressure natural gas in the circulation pipe 4 does not exceed 15°C, open the bypass pipe 8 so that the gas output from the first heat exchange outlet and the second heat exchange outlet can directly enter the downstream natural gas inlet 6.

[0053] This invention discloses a combined natural gas waste pressure power generation and ice-making system, comprising a pressure regulating power generation device 2, an ice-making device 3, a pre-cooling chamber 1, and a circulation pipeline 4. The pre-cooling chamber 1 is located between the pressure regulating power generation device 2 and an upstream natural gas outlet 5. The pre-cooling chamber 1 is provided with an inlet and an outlet. The pressure regulating power generation device 2 is connected to the upstream natural gas outlet 5 via a high-pressure gas supply pipeline 7 passing through the pre-cooling chamber 1. The ice-making device 3 is connected to one end of the circulation pipeline 4, and the other end of the circulation pipeline 4 is connected to the inlet of the pre-cooling chamber 1. The outlet of the pre-cooling chamber 1 is connected to the downstream natural gas outlet. This invention establishes a pre-cooling chamber 1 between the upstream natural gas outlet 5 and the pressure regulating power generation device 2, recirculating the natural gas after pressure reduction power generation and cold energy ice-making into the pre-cooling chamber 1 to pre-cool the upstream natural gas. Simultaneously, the natural gas after cold energy utilization absorbs heat from the upstream natural gas to reach a temperature close to the downstream natural gas's operating temperature, achieving full utilization of energy before and after natural gas pressure regulation.

[0054] The above are merely embodiments of the present invention, described in a relatively specific and detailed manner, but should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention.

Claims

1. A combined system for power generation and ice making using natural gas waste pressure, characterized in that: Includes a pre-cooling chamber, a voltage regulating power generation unit, an ice-making unit, and circulation pipes; The precooling chamber is located between the upstream natural gas outlet and the pressure regulating power generation device; the pressure regulating power generation device is connected to the upstream natural gas outlet through a high-pressure gas supply pipeline passing through the precooling chamber; The ice-making device includes a first heat exchanger and a second heat exchanger, and the voltage regulating power generation device is connected to the first heat exchanger and the second heat exchanger respectively; One end of the circulation pipe is connected to the ice-making device, and the other end is connected to the air inlet of the precooling chamber; The precooling chamber includes a first precooling room and a second precooling room; the circulation pipe is connected to the second precooling room; The inner sidewall of the precooling chamber is spiral-shaped, and the spiral direction is opposite to the airflow direction in the high-pressure gas supply pipeline. The air inlet is funnel-shaped, and the diameter of the air inlet gradually increases from the end away from the precooling chamber to the end closer to the precooling chamber. The voltage regulating power generation device includes an expander and a generator. The expander is connected to the upstream natural gas outlet through the high-pressure gas supply pipeline, and the expander is connected to the generator. The expander is further provided with a first air outlet and a second air outlet; the first air outlet is connected to the first heat exchanger, and the second air outlet is connected to the second heat exchanger. The ice-making device also includes a first water storage tank, an evaporator, a compressor, and an ice maker; one end of the evaporator is connected to a refrigerant input pipe that communicates with the precooling chamber, and the other end is connected to the compressor; the compressor is connected to the second heat exchanger through the air inlet of the second heat exchanger; The first heat exchanger is provided with a first heat exchange air outlet and a first heat exchange liquid outlet; the first heat exchange air outlet is connected to the circulation pipe; the first heat exchange liquid outlet is connected to the ice maker. The second heat exchanger is provided with a second heat exchange air outlet and a second heat exchange liquid outlet; the second heat exchange air outlet is connected to the circulation pipe; the second heat exchange liquid outlet is connected to the ice maker. The first water storage tank is connected to the first heat exchanger; The ice-making device also includes a second water storage tank, which is connected to the first water storage tank. The low-pressure natural gas output from the first heat exchange outlet and the second heat exchange outlet passes through the second water storage tank before entering the circulation pipeline.

2. The natural gas waste pressure power generation and ice-making combined system according to claim 1, characterized in that: The refrigerant input pipeline is connected to the first precooling room, and the ice maker is connected to the first precooling room through the refrigerant liquid return pipeline; the high-pressure natural gas input from the upstream natural gas outlet passes through the first precooling room and the second precooling room in sequence and enters the pressure regulating power generation device through the high-pressure gas supply pipeline.

3. The natural gas waste pressure power generation and ice-making combined system according to claim 1, characterized in that: The air inlet is inclined into the precooling chamber; and the angle between the axis of the air inlet and the inner wall of the precooling chamber is 30-45°.

4. The natural gas waste pressure power generation and ice-making combined system according to claim 1, characterized in that: A first pressure-regulating valve is installed on the high-pressure gas supply pipeline, and a second pressure-regulating valve is installed on the circulation pipeline.

5. A combined natural gas waste pressure power generation and ice-making system according to claim 1, characterized in that: The circulation pipeline is also equipped with a bypass pipeline that connects to the downstream natural gas inlet.

6. A combined natural gas waste pressure power generation and ice-making system according to claim 5, characterized in that: The circulation pipe and the bypass pipe are connected by a three-way valve.

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