A gas storage residual pressure and residual heat coupled power generation system and method

Abstract

The application discloses a kind of gas storage residual pressure and residual heat coupling power generation system and method, in system, gas pipe network is connected with expander and generator set by first heat exchanger, and expander and generator set are connected with gas injection compressor and power generation grid-connected access assembly respectively;Second heat exchanger is installed in the interstage of multistage compressor, and second heat exchanger and first heat exchanger are circulated by intermediate medium circulating pump heat exchange;Natural gas is heated after passing through first heat exchanger, and power generation is carried out while being depressurized by expander and generator set, realizes power grid connection, and natural gas after being depressurized is compressed by gas injection compressor, second heat exchanger exchanges heat generated in the process of compression, and heat is circulated to first heat exchanger by intermediate medium circulating pump.Through the technical scheme of the application, the waste heat recovery of gas injection compressor and the power generation of residual pressure during gas injection are realized, the residual energy recovery and utilization of gas storage are strengthened, and the energy utilization rate of gas storage is effectively improved.

Description

Technical Field

[0001] This invention relates to the field of natural gas storage and transportation technology, and in particular to a gas storage facility waste pressure and waste heat coupled power generation system and a gas storage facility waste pressure and waste heat coupled power generation method. Background Technology

[0002] As a form of city gas, the consumption of natural gas varies significantly with the seasons, making peak-shaving an increasingly prominent issue. Currently, most of the solutions rely on underground gas storage facilities to address seasonal and monthly unevenness. During the gas injection period, pipeline natural gas is pressurized and stored underground in the storage facility, and during the extraction period, i.e., the peak gas consumption period, it is extracted from underground and supplied to various users.

[0003] Because the gas pressure in the natural gas pipeline network fluctuates significantly, when the gas pressure during the injection period is high and exceeds the inlet pressure that the gas injection compressor of the gas storage facility can handle, it is necessary to reduce the pressure to the inlet pressure required by the gas injection compressor before it is pressurized and injected underground. At the same time, because the gas volume injected into the gas storage facility during the injection period is large and the injection pressure is high, the gas injection compressor generates a lot of heat during operation. Generally, the high-temperature natural gas after compression is cooled by the cooling system configured in the compressor unit. As a result, a large amount of pressure energy and waste heat of the gas injection compressor during the gas storage facility injection period are not effectively utilized, resulting in energy waste. Summary of the Invention

[0004] To address the aforementioned problems, this invention provides a gas storage waste pressure and waste heat coupled power generation system and method. Through cyclic heat exchange between the second heat exchanger and the first heat exchanger, the heat generated during the pressurization process of the gas injection compressor is transferred to the natural gas output from the gas storage. The heated natural gas is then depressurized through an expander and a generator set to generate electricity. This achieves waste heat recovery from the gas injection compressor and waste pressure power generation during the gas injection period, enhancing the recovery and utilization of waste energy in the gas storage and effectively improving the energy utilization rate of the gas storage.

[0005] To achieve the above objectives, the present invention provides a gas storage waste pressure and waste heat coupled power generation system, comprising: a first heat exchanger, an expander and generator set, a gas injection compressor, a power generation grid connection component, a second heat exchanger and an intermediate medium circulation pump;

[0006] The gas transmission pipeline is connected to the input end of the expander and generator set through the first heat exchanger, the output end of the expander and generator set is connected to the gas injection compressor, and the expander and generator set is connected to the power generation grid connection component.

[0007] The output end of the gas injection compressor is connected to the gas storage tank through the gas injection pipeline. The second heat exchanger is installed between the stages of the multi-stage compressor of the gas injection compressor. The second heat exchanger and the first heat exchanger exchange heat through the intermediate medium circulation pump.

[0008] The natural gas input from the gas pipeline is heated by the first heat exchanger, then depressurized by the expander and generator set while generating electricity. The power generation is connected to the grid by the grid-connected power generation component. The gas injection compressor compresses the depressurized natural gas step by step to a preset pressure and outputs it to the gas injection pipeline. The second heat exchanger exchanges heat with the gas injection compressor during the compression process and circulates the heat to the first heat exchanger through the intermediate medium circulation pump.

[0009] In the above technical solution, preferably, a filter separator is provided at the output end of the gas transmission pipeline network. The filter separator is connected to the first heat exchanger. The natural gas input from the gas transmission pipeline network is filtered and separated by the filter separator and then output to the first heat exchanger for heat exchange.

[0010] In the above technical solution, preferably, the gas injection compressor includes a primary compressor, a secondary compressor, and a tertiary compressor, which are connected in series. The input end of the primary compressor is connected to the output end of the expander and the generator set, and the output end of the tertiary compressor is connected to the gas injection pipeline. The second heat exchanger is installed between the secondary compressor and the tertiary compressor.

[0011] In the above technical solution, preferably, the output end of the second heat exchanger is connected to the input end of the first heat exchanger, the input end of the intermediate medium circulation pump is connected to the output end of the first heat exchanger, and the output end of the intermediate medium circulation pump is connected to the input end of the second heat exchanger. The pumping action of the intermediate medium circulation pump realizes the circulating heat exchange from the second heat exchanger to the first heat exchanger.

[0012] In the above technical solution, preferably, the expander and the generator in the expander and generator set are coaxially installed, and the expander drives the coaxial generator to generate electricity while depressurizing the natural gas.

[0013] This invention also proposes a method for coupled power generation using waste pressure and waste heat from a gas storage facility, applicable to the coupled power generation system using waste pressure and waste heat from a gas storage facility disclosed in any of the above technical solutions, comprising:

[0014] The natural gas from the gas pipeline is sent to the first heat exchanger for heating, and the heated natural gas is then sent to the expander and generator set.

[0015] The expander and generator set generate electricity while depressurizing the heated high-pressure natural gas, and achieve grid connection through the power generation and grid connection component;

[0016] The natural gas after pressure reduction is compressed in stages by the gas injection compressor, and the heat generated during the compression process is exchanged by the second heat exchanger. After the natural gas is compressed to the preset pressure, it is injected into the gas storage tank through the gas injection pipeline.

[0017] The heat obtained from the second heat exchanger is transferred to the first heat exchanger through an intermediate medium circulation pump to achieve circulating heat exchange.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows: through the circulating heat exchange between the second heat exchanger and the first heat exchanger, the heat generated during the pressurization process of the gas injection compressor is transferred to the natural gas input into the gas transmission pipeline. The heated natural gas is depressurized through the expander and generator set to generate electricity at the same time, realizing the recovery of waste heat from the gas injection compressor and the power generation of waste pressure during the gas injection period, strengthening the recovery and utilization of waste energy in the gas storage facility, and effectively improving the energy utilization rate of the gas storage facility. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the process flow of a gas storage waste pressure and waste heat coupled power generation system disclosed in one embodiment of the present invention.

[0020] In the diagram, the correspondence between the components and the reference numerals is as follows:

[0021] 1. First heat exchanger, 2. Expander and generator set, 3. First stage compressor, 4. Second stage compressor, 5. Third stage compressor, 6. Power generation grid connection component, 7. Second heat exchanger, 8. Intermediate medium circulation pump, 9. Filter separator. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] The present invention will now be described in further detail with reference to the accompanying drawings:

[0024] like Figure 1 As shown, a gas storage waste pressure and waste heat coupled power generation system according to the present invention includes: a first heat exchanger 1, an expander and generator set 2, a gas injection compressor, a power generation grid connection component 6, a second heat exchanger 7, and an intermediate medium circulation pump 8.

[0025] The gas transmission pipeline is connected to the input end of the expander and generator set 2 through the first heat exchanger 1. The output end of the expander and generator set 2 is connected to the gas injection compressor. The expander and generator set 2 is connected to the power generation grid connection component 6.

[0026] The output end of the gas injection compressor is connected to the gas storage tank through the gas injection pipeline. The second heat exchanger 7 is installed between the stages of the multi-stage compressor of the gas injection compressor. The second heat exchanger 7 and the first heat exchanger 1 exchange heat through the intermediate medium circulation pump 8.

[0027] Natural gas input from the gas pipeline is heated by the first heat exchanger 1, then depressurized by the expander and generator set 2 while generating electricity. The electricity is then connected to the grid by the power generation grid connection component 6. The gas injection compressor compresses the depressurized natural gas step by step to the preset pressure and outputs it to the gas injection pipeline. The second heat exchanger 7 exchanges the heat generated during the compression process of the gas injection compressor and circulates the heat to the first heat exchanger 1 through the intermediate medium circulation pump 8.

[0028] In this embodiment, the heat generated during the pressurization process of the gas injection compressor is transferred to the natural gas output from the gas storage tank through the circulating heat exchange between the second heat exchanger 7 and the first heat exchanger 1. The heated natural gas is depressurized through the expander and generator set 2 to generate electricity, thereby realizing the recovery of waste heat from the gas injection compressor and the generation of residual pressure during the gas injection period. This strengthens the recovery and utilization of residual energy in the gas storage tank and effectively improves the energy utilization rate of the gas storage tank.

[0029] Specifically, the natural gas supplied by the pipeline first enters the first heat exchanger 1 to exchange heat with the intermediate medium before entering the expander and generator set 2. After expansion and depressurization, it enters the downstream existing injection compressor. Simultaneously, the intermediate medium exchanges heat with the interstage process gas of the injection compressor through the second heat exchanger 7, then circulates back to the first heat exchanger 1 to exchange heat with the natural gas, and then undergoes pressurization and circulation heat exchange through the intermediate medium circulation pump 8. During the expansion and depressurization process, the potential energy of the natural gas during depressurization is converted into kinetic energy, and then into electrical energy. The generated electricity is used in conjunction with the grid, realizing the coupled power generation of waste pressure and waste heat. This effectively utilizes the waste pressure and waste heat resources of the gas storage facility, reduces energy waste, and is conducive to energy conservation, emission reduction, and green development, while bringing economic benefits and environmental value to the gas storage facility.

[0030] In the above embodiment, preferably, a filter separator 9 is installed at the output end of the gas pipeline network. The filter separator 9 is connected to the first heat exchanger 1. The natural gas input from the gas pipeline network is filtered and separated by the filter separator 9 before being output to the first heat exchanger 1 for heat exchange. The filter separator 9 can not only remove various tiny particles from the natural gas, but also effectively remove moisture, fibers, and suspended solids. It is an ideal oil purification device and is also suitable for various fine chemical raw materials that require purification.

[0031] In the above embodiment, preferably, the gas injection compressor includes a primary compressor 3, a secondary compressor 4 and a tertiary compressor 5, which are connected in series. The input end of the primary compressor 3 is connected to the output end of the expander and generator set 2, and the output end of the tertiary compressor 5 is connected to the gas injection pipeline. The second heat exchanger 7 is installed between the secondary compressor 4 and the tertiary compressor 5.

[0032] Specifically, in order to adapt to the inlet pressure of the gas injection compressor, the natural gas needs to be depressurized first. At the same time, in order to effectively utilize the residual pressure potential energy of the high-pressure natural gas, the expander and generator set 2 are used to expand and depressurize the natural gas to generate electricity.

[0033] Then, the natural gas is pressurized step by step to the required pressure using a multi-stage compressor in the injection compressor, and then injected into the underground gas storage facility. During this process, the heat generated by pressurization is transferred to the natural gas output from the gas storage facility through the circulation heat exchange of the second heat exchanger 7, the intermediate medium circulation pump 8, and the first heat exchanger 1, thereby heating the natural gas. The heated natural gas has higher potential energy during the depressurization power generation process of the expander and generator set 2, thus realizing the utilization of waste heat.

[0034] In this embodiment, the gas injection compressor adopts a multi-stage pressurization method. Specifically, during implementation, the gas injection compressor can use at least two stages, such as two-stage or four-stage pressurization. The installation location of the second heat exchanger should consider both the full utilization of heat during the pressurization process (i.e., installing it as late as possible in the pressurization stage when heat accumulation has reached a certain amount) and the increased equipment cost due to pressure increase during the pressurization process, thus balancing cost considerations with full utilization of heat during the pressurization process.

[0035] In the above embodiment, preferably, the output end of the second heat exchanger 7 is connected to the input end of the first heat exchanger 1, the input end of the intermediate medium circulation pump 8 is connected to the output end of the first heat exchanger 1, and the output end of the intermediate medium circulation pump 8 is connected to the input end of the second heat exchanger 7. The pumping action of the intermediate medium circulation pump 8 realizes the circulating heat exchange from the second heat exchanger 7 to the first heat exchanger 1.

[0036] In the above embodiments, preferably, the expander and generator in the expander and generator set 2 are coaxially mounted. The expander drives the coaxial generator to generate electricity while depressurizing the natural gas. The power generation grid connection component 6 includes a grid connection cabinet and a 10kV distribution room switch cabinet. The power generated by the generator is transmitted and distributed through the grid connection cabinet and the 10kV distribution room switch cabinet, and finally connected to the power grid.

[0037] like Figure 1As shown, the filter separator 9, pressure regulating valve, primary compressor 3, secondary compressor 4, tertiary compressor 5, and air cooler installed after each stage compressor 3 are components of existing underground gas storage devices. Based on this, the present invention adds a first heat exchanger 1, an expander and generator set 2, a power generation grid connection component 6, a second heat exchanger 7, and an intermediate medium circulation pump 8. During implementation, the air cooler and the second heat exchanger 7 are connected in series, and the bypass channel of the second heat exchanger 7 is closed by a valve, thus obtaining the gas storage waste pressure and waste heat coupled power generation system disclosed in this invention. The modification is simple and cost-effective.

[0038] This invention also proposes a method for coupled power generation using waste pressure and waste heat from a gas storage facility, applicable to the coupled power generation system using waste pressure and waste heat from a gas storage facility disclosed in any of the above embodiments, comprising:

[0039] The natural gas from the gas pipeline is sent to the first heat exchanger 1 for heating, and the heated natural gas is sent to the expander and generator set 2.

[0040] The expander and generator set 2 reduces the pressure of the heated high-pressure natural gas while generating electricity, and connects to the power grid through the power generation and grid connection component 6;

[0041] The natural gas after pressure reduction is compressed in stages by the gas injection compressor, and the heat generated during the compression process is exchanged through the second heat exchanger 7. After the natural gas is compressed to the preset pressure, it is injected into the underground gas storage through the gas injection pipeline.

[0042] The heat obtained from the second heat exchanger 7 is transferred to the first heat exchanger 1 through the intermediate medium circulation pump 8 to achieve circulating heat exchange.

[0043] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A system for generating power from the excess pressure and excess heat of a gas storage, characterized in that, include: First heat exchanger, expander and generator set, gas injection compressor, power generation grid connection assembly, second heat exchanger and intermediate medium circulation pump; The gas transmission pipeline is connected to the input end of the expander and generator set through the first heat exchanger, the output end of the expander and generator set is connected to the gas injection compressor, and the expander and generator set is connected to the power generation grid connection component. The output end of the gas injection compressor is connected to the gas storage tank through a gas injection pipeline. The second heat exchanger is installed between the stages of the multi-stage compressor of the gas injection compressor. The second heat exchanger and the first heat exchanger exchange heat through the intermediate medium circulation pump. The output end of the second heat exchanger is connected to the input end of the first heat exchanger. The input end of the intermediate medium circulation pump is connected to the output end of the first heat exchanger. The output end of the intermediate medium circulation pump is connected to the input end of the second heat exchanger. The pumping action of the intermediate medium circulation pump realizes the circulating heat exchange from the second heat exchanger to the first heat exchanger. The natural gas input from the gas pipeline is heated by the first heat exchanger, then depressurized by the expander and generator set while generating electricity. The power generation is connected to the grid by the grid-connected power generation component. The gas injection compressor compresses the depressurized natural gas step by step to a preset pressure and outputs it to the gas injection pipeline. The second heat exchanger exchanges heat with the gas injection compressor during the compression process and circulates the heat to the first heat exchanger through the intermediate medium circulation pump.

2. The system according to claim 1, wherein, A filter separator is installed at the output end of the gas transmission pipeline. The filter separator is connected to the first heat exchanger. The natural gas input into the gas transmission pipeline is filtered and separated by the filter separator and then output to the first heat exchanger for heat exchange.

3. The system of claim 1, wherein, The gas injection compressor includes a primary compressor, a secondary compressor, and a tertiary compressor, which are connected in series. The input end of the primary compressor is connected to the output end of the expander and generator set, and the output end of the tertiary compressor is connected to the gas injection pipeline. The second heat exchanger is installed between the secondary compressor and the tertiary compressor.

4. The system of claim 1, wherein, The expander and generator set are coaxially mounted. The expander reduces the pressure of the natural gas while driving the coaxial generator to generate electricity.

5. A method for generating power by coupling the surplus pressure and surplus heat of a gas storage, characterized by, The gas storage waste pressure and waste heat coupled power generation system applied to any one of claims 1 to 4 includes: The natural gas from the gas pipeline is sent to the first heat exchanger for heating, and the heated natural gas is then sent to the expander and generator set. The expander and generator set generate electricity while depressurizing the heated high-pressure natural gas, and achieve grid connection through the power generation and grid connection component; The natural gas after pressure reduction is compressed in stages by the gas injection compressor, and the heat generated during the compression process is exchanged by the second heat exchanger. After the natural gas is compressed to the preset pressure, it is injected into the gas storage tank through the gas injection pipeline. The heat obtained by heat exchange of the second heat exchanger is transmitted to the first heat exchanger through an intermediate medium circulating pump, so as to realize circulating heat exchange.

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