CN214170637U - LNG cold energy step power generation system - Google Patents
LNG cold energy step power generation system Download PDFInfo
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- CN214170637U CN214170637U CN202022639334.7U CN202022639334U CN214170637U CN 214170637 U CN214170637 U CN 214170637U CN 202022639334 U CN202022639334 U CN 202022639334U CN 214170637 U CN214170637 U CN 214170637U
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Abstract
The utility model discloses a LNG cold energy step power generation system. LNG cold energy cascade power generation system includes evaporation plant, the expander, power generation facility, a plurality of condensing equipment and a plurality of pressure regulating component, evaporation plant is used for forming working medium steam, the expander is used for driving power generation facility electricity generation, the expander includes an expander import and a plurality of expander exports, the working medium steam that comes from evaporation plant can get into the expander in order to form the working medium exhaust steam of different pressures, the working medium exhaust steam of different pressures is respectively from a plurality of expander exports discharge, the working medium exhaust steam of different pressures respectively with the LNG heat exchange among a plurality of condensing equipment in order to form the organic working medium of different pressures, a plurality of pressure regulating component are used for the pressure adjustment unanimity of the organic working medium of different pressures. According to the utility model discloses a LNG cold energy step power generation system can improve the utilization ratio of LNG cold energy, reduces the cold and hot loss among the heat transfer process to further improve LNG cold energy step power generation system's generating power.
Description
Technical Field
The utility model relates to an energy environmental protection technology field particularly relates to a LNG cold energy step power generation system.
Background
Natural gas is a low-carbon energy source and has the characteristics of cleanness, high efficiency and high quality. The main transportation mode of natural gas is to reduce the temperature of the natural gas to about minus 162 ℃ and then convert the natural gas into Liquefied Natural Gas (LNG), and the natural gas is transported by a marine Liquefied Natural Gas (LNG) ship after the natural gas is converted into gaseous 1/600. Whereas LNG must be vaporized before it is supplied to the consumer for use. The temperature of the gasification process of the liquefied natural gas is constantly changed, and the gasification process of the liquefied natural gas carries a large amount of cold energy, so that the liquefied natural gas gasification device has extremely high utilization value.
Therefore, there is a need to provide an LNG cold energy cascade power generation system to at least partially solve the above problems.
SUMMERY OF THE UTILITY MODEL
In the summary section a series of concepts in a simplified form is introduced, which will be described in further detail in the detailed description section. The inventive content does not imply any attempt to define the essential features and essential features of the claimed solution, nor is it implied to be intended to define the scope of the claimed solution.
In order to solve the above problem at least partially, according to a first aspect of the present invention, there is provided an LNG cold energy step power generation system, including:
the evaporation device comprises a working medium pipeline and is used for carrying out heat exchange on a heat source and an organic working medium in the working medium pipeline to form working medium steam;
the expansion machine comprises an expansion machine inlet and a plurality of expansion machine outlets, the expansion machine inlet is communicated with the working medium pipeline of the evaporation device, so that the working medium steam from the evaporation device can enter the expansion machine to form working medium exhaust steam with different pressures, and the working medium exhaust steam with different pressures is discharged from the plurality of expansion machine outlets respectively;
the power generation device is in transmission connection with the expansion machine so as to convert mechanical energy into electric energy;
the plurality of condensing devices are arranged corresponding to the outlets of the plurality of expanders, connected in parallel between the expanders and the evaporating devices through pipelines, and connected in series through LNG pipelines, so that the working medium exhaust steam with different pressures is subjected to heat exchange with LNG in the plurality of condensing devices respectively to form organic working media with different pressures; and
the pressure regulating members are respectively arranged on pipelines between the evaporation device and the condensing devices and used for adjusting the pressure of the organic working medium with different pressures to be consistent.
According to the LNG cold energy cascade power generation system of the utility model, the LNG cold energy cascade power generation system comprises an evaporation device, an expander, a power generation device, a plurality of condensing units and a plurality of pressure regulating members, the evaporation device comprises a working medium pipeline, the evaporation device is used for heat exchange between a heat source and an organic working medium in the working medium pipeline to form working medium steam, the expander comprises an expander inlet and a plurality of expander outlets, the expander inlet is communicated with the working medium pipeline of the evaporation device, so that the working medium steam from the evaporation device can enter the expander to form working medium exhaust steam with different pressures, the working medium exhaust steam with different pressures is respectively discharged from the plurality of expander outlets, the power generation device is in transmission connection with the expander to convert mechanical energy into electric energy, the plurality of condensing units are correspondingly arranged with the plurality of expander outlets, the plurality of condensing units are connected in parallel between the expander and the evaporation device via the pipeline, and the plurality of condensing units are connected in series through LNG pipelines so that working medium exhaust steam with different pressures exchanges heat with LNG in the plurality of condensing units respectively to form organic working media with different pressures, and the plurality of pressure regulating members are arranged on the pipelines between the evaporating unit and the plurality of condensing units respectively so as to regulate the pressures of the organic working media with different pressures uniformly. Therefore, the LNG cold energy cascade power generation system can effectively utilize the constantly changing gasification temperature in the LNG gasification process, and the condensation curve of the dead steam of the working medium is matched with the gasification curve of the LNG by improving the temperature of the LNG at the outlet of the LNG pipeline, so that the utilization rate of the LNG cold energy is improved, the cold and heat loss in the heat exchange process is reduced, and the power generation power of the LNG cold energy cascade power generation system is further improved.
Optionally, the expander further comprises a multi-stage rotating member, the working medium steam sequentially enters the multi-stage rotating member to expand and do work to form the working medium exhaust steam with different pressures, and the working medium exhaust steam from the multi-stage rotating member is discharged through the plurality of expander outlets respectively. Therefore, the working medium steam can respectively expand and do work in the expansion machine, and power is generated respectively.
Optionally, the mass flow rate of the working medium steam at the inlet of the expansion machine is equal to the sum of the mass flow rates of the working medium dead steam at the outlets of the multiple expansion machines. According to the scheme, the energy loss is reduced when the expansion machine does work.
Optionally, the mass flow rates of the working medium exhaust steam at the outlets of the plurality of expansion machines are equal or different. Thereby improving the utilization rate of cold energy.
Optionally, the LNG absorbs energy equal to the sum of the energy released by the working medium exhaust steam discharged from the plurality of expander outlets. Thereby improving the utilization rate of the cold energy of the LNG.
Optionally, the pressure and/or temperature of the working medium exhaust steam of the plurality of condensing devices are sequentially increased along the flow direction of the LNG. Thereby improving heat exchange efficiency and LNG cold energy utilization.
Optionally, the heat source is seawater, air, solar energy, geothermal energy, hot water, steam, flue gas, circulating water, or a process fluid. Therefore, the energy of the existing substances can be effectively utilized, and the effects of energy conservation and environmental protection are achieved.
Optionally, the organic working fluid is a mixture of one or more of methane, ethane, propane, ethylene, propylene, tetrafluoroethane, ammonia, and the like. Therefore, the energy of the existing substances can be effectively utilized, the effects of energy conservation and environmental protection are achieved, meanwhile, the liquefaction temperature of the organic working medium and the LNG gasification temperature can be well matched, and the power generation efficiency is improved.
Optionally, the expander is one or more of an axial flow turboexpander, a centrifugal turboexpander, a radial turboexpander or a screw expander. Therefore, various expanders can be applied, and the application range is expanded.
Drawings
The following drawings of the present invention are used herein as part of the present invention for understanding the present invention. There are shown in the drawings embodiments of the invention and the description thereof for the purpose of illustrating the devices and principles of the invention. In the drawings, there is shown in the drawings,
fig. 1 is a schematic diagram of an LNG cold energy cascade power generation system according to a preferred embodiment of the present invention;
FIG. 2 is a schematic diagram of a condensation curve of the dead steam of the working medium and a gasification temperature curve of LNG shown in FIG. 1; and
fig. 3 is a flow chart of a method of generating power according to a preferred embodiment of the present invention.
Description of reference numerals:
100: LNG cold energy cascade power generation system 110: evaporation device
111: heat source line 112: evaporation pipeline
120: the expander 121: outlet of the first expander
122: second expander outlet 123: outlet of the third expander
124: expander inlet 130: power generation device
141: first condensing device 142: second condensing device
143: third condensing device 151: first expansion pipeline
152: second expansion line 153: third expansion pipeline
171: first pressure regulating member 172: second pressure regulating member
173: third pressure regulating member 191: inlet of LNG pipeline
192: LNG pipeline outlet
Detailed Description
In the following description, numerous specific details are set forth in order to provide a more thorough understanding of the present invention. It will be apparent, however, to one skilled in the art, that the present invention may be practiced without one or more of these specific details. In other instances, well-known features have not been described in order to avoid obscuring the present invention.
In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the present invention. It is apparent that the practice of the invention is not limited to the specific details known to those skilled in the art. The present invention is described in detail below with reference to the preferred embodiments, however, the present invention can have other embodiments in addition to the detailed description, and should not be construed as being limited to the embodiments set forth herein.
It is to be understood that the terms "a," "an," and "the" as used herein are intended to describe specific embodiments only and are not to be taken as limiting the invention, which is intended to include the plural forms as well, unless the context clearly indicates otherwise. When the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. The terms "upper", "lower", "front", "rear", "left", "right" and the like as used herein are for illustrative purposes only and are not limiting.
Ordinal words such as "first" and "second" are referred to in this application as labels only, and do not have any other meanings, such as a particular order, etc. Also, for example, the term "first component" does not itself imply the presence of "second component", and the term "second component" does not itself imply the presence of "first component".
Hereinafter, specific embodiments of the present invention will be described in more detail with reference to the accompanying drawings, which illustrate representative embodiments of the present invention and do not limit the present invention.
As shown in fig. 1, the utility model provides a LNG cold energy step power generation system 100, LNG cold energy step power generation system 100 can utilize the cold energy that LNG carried effectively to generate electricity, and the rate of utilization is improved, reduces the waste of the energy.
The LNG cold energy cascade power generation system 100 comprises an evaporation device 110, an expander 120, a power generation device 130, a plurality of condensing devices and a plurality of pressure regulating members, wherein an organic working medium is arranged in the LNG cold energy cascade power generation system 100, and the organic working medium can exchange heat with LNG so as to absorb a large amount of cold energy carried by the LNG. The power generation device is in transmission connection with the expansion machine so as to convert the mechanical energy into electric energy and generate power.
Specifically, the evaporation device 110 includes a working medium pipeline, an organic working medium is disposed in the working medium pipeline, and the heat source can exchange heat with the organic working medium in the working medium pipeline. The temperature of the organic working medium is lower than that of the heat source, and the organic working medium can absorb the energy of the heat source to form working medium steam.
Preferably, the heat source can be free natural resources such as seawater, air and the like, and the heat source can also be waste heat resources such as hot water, steam, flue gas, circulating water or process fluid and the like. The process fluid may be a fluid generated by a process, the fluid including a gas and a liquid. Alternatively, the process fluid may be a process wastewater. The evaporation apparatus may include a heat source pipe 111, and a heat source such as a fluid is disposed in the heat source pipe 111. The heat source in the heat source pipeline 111 can exchange heat with the organic working medium in the working medium pipeline. Of course, the heat source can also be solar energy or geothermal energy to directly exchange heat with the organic working medium. Therefore, the energy of the existing substances can be effectively utilized, and the effects of energy conservation and environmental protection are achieved. Preferably, the organic working fluid is a mixture of one or more of methane, ethane, propane, ethylene, propylene, tetrafluoroethane, ammonia and the like. Therefore, the energy carried by the heat source can be effectively absorbed, the energy loss in the heat exchange process is reduced, and the efficiency is improved.
The expander 120 may include an expander inlet 124 and a plurality of expander outlets, and the expander inlet 124 may be connected to the working fluid line of the evaporation device 110 through the evaporation line 112, so that the working fluid steam from the evaporation device 110 can enter the expander 120 to form working fluid exhaust steam with different pressures. The outlets of the expansion machines can respectively correspond to a plurality of pressure grades of the working medium exhaust steam. The expander 120 may also be in driving connection with the power generation device 130 for driving the power generation device 130 to generate power. Preferably, the expander 120 may be one or more of an axial-flow turboexpander, a centrifugal turboexpander, a radial-flow turboexpander, or a screw expander. Therefore, the LNG cold energy cascade power generation system 100 can be applied to various expansion machines 120, and the application range is expanded.
After entering the expander 120 through the expander inlet 124 for expansion work, the working medium steam expands to a certain pressure, one part of the working medium steam is discharged from one of the multiple expander outlets, and the other part of the working medium steam continues to perform expansion work, so that the expander 120 can drive the power generation device 130 to realize multi-stage power generation to generate working medium exhaust steam with different pressures.
Working medium exhaust steam with different pressures can be discharged from outlets of the plurality of expansion machines respectively. The plurality of expander outlets are provided corresponding to a plurality of condensing devices connected in parallel between the expander 120 and the evaporation device 110 via a pipe. A plurality of condensing equipment establish ties through the LNG pipeline, is provided with LNG in the LNG pipeline. Thus, the working medium exhaust steam from the expander 120 can exchange heat with LNG via the condensing device to form an organic working medium, and the organic working medium flows back to the evaporating device 110 to exchange heat with the heat source.
Preferably, the expander 120 further includes multiple stages of rotating members, and the working medium steam can sequentially enter the multiple rotating members to expand and do work to form working medium exhaust steam with different pressures. The rotating member may be configured as an impeller or a screw capable of expanding to perform work. The impeller or screw may rotate. For example, the expander 120 includes a first expander outlet 121, a second expander outlet 122, and a third expander outlet 123, the plurality of condensing devices includes a first condensing device 141, a second condensing device 142, and a third condensing device 143, and the lines may include a first expansion line 151, a second expansion line 152, and a third expansion line 153. The first expander outlet 121, the second expander outlet 122 and the third expander outlet 123 can simultaneously discharge the working medium dead steam. The multi-stage rotating member includes a 1 st stage rotating member, a 2 nd stage rotating member, and a 3 rd stage rotating member. Of course, the expander 120 may include a greater number of expander outlets and a greater number of rotating members to create a greater amount of exhaust steam of the working fluid at different pressures. For simplicity of the page, only three expander outlets, three condensing devices and three expansion lines are shown in fig. 1.
The working medium steam in the expander 120 can enter the 1 st-stage rotating member to perform expansion work, and is expanded to a certain pressure to form working medium exhaust steam, and a part of the working medium exhaust steam is discharged from the first expander outlet 121. The pressure of the working medium exhaust steam discharged from the outlet 121 of the first expansion machine is P1. The other part of the working medium steam continues to enter the 2 nd-stage rotating member for expansion and working, and the expansion is carried out to another fixed partAnother portion of the working fluid exhaust steam is discharged from second expander outlet 122 under pressure. The pressure of the dead steam of the working medium discharged from the outlet 122 of the second expander is P2. And a part of the working medium steam continues to enter the 3 rd-stage rotating member for expansion and work application, the working medium steam expands to a certain pressure, and a part of the working medium exhaust steam is discharged from an outlet 123 of the third expander. The pressure of the working medium exhaust steam discharged from the outlet 123 of the third expansion machine is P3。
The first expansion line 151 communicates with the first expander outlet 121. The waste steam of the working medium from the outlet 121 of the first expansion machine can be introduced into the first condensation device 141 via the first expansion line 151. The second expansion line 152 communicates with the second expander outlet 122. The spent working fluid steam from the second expander outlet 122 may enter the second condensing device 142 through a second expansion line 152. The third expansion line 153 communicates with the third expander outlet 123. The dead steam of the working fluid from the outlet 123 of the third expansion machine can be introduced into the third condensation device 143 through the third expansion line 153.
Furthermore, a plurality of condensing units are connected in series through LNG pipelines, LNG is arranged in the LNG pipelines, and the LNG can enter the condensing units respectively and exchanges heat with different working medium exhaust steam in different condensing units. Working medium exhaust steam with different pressures can exchange heat with LNG in a plurality of condensing units to form organic working media with different pressures. Different condensing units can receive cold energy of different temperature sections in the LNG gasification process, and working medium exhaust steam entering the condensing units is condensed into organic working medium under corresponding pressure.
Specifically, the LNG line includes an inlet 191 and an outlet 192, the inlet 191 of the LNG line may be adjacent to the third condensing unit 143, and the outlet 192 of the LNG line may be adjacent to the first condensing unit 141. The LNG may first enter the third condensing unit 143, and the LNG absorbs energy of the dead steam of the working medium in the third expansion line 153 to be gasified. Working medium exhaust steam in the third expansion pipeline 153 is condensed to form organic working medium. The LNG may sequentially enter the second condensing unit 142, and the LNG absorbs energy of the dead steam of the working medium in the second expansion line 152 to be gasified. Working medium exhaust steam in the second expansion pipeline 152 is condensed to form organic working medium. The LNG may sequentially enter the first condensing unit 141, and the LNG absorbs energy of the dead steam of the working medium in the first expansion line 151 to be gasified.
The temperature of the LNG at the outlet 192 of the LNG pipeline is higher than that of the LNG at the inlet 191 of the LNG pipeline, that is, the LNG cold energy step power generation system increases the outlet temperature of the LNG. And the working medium exhaust steam in each expansion pipeline is condensed to form the organic working medium. The organic working medium formed by the first condensing device 141, the organic working medium formed by the second condensing device 142 and the organic working medium formed by the third condensing device 143 have different pressures.
The organic working mediums with different pressures can enter the evaporation device 110 through a plurality of pressure regulating members respectively. The plurality of pressure regulating members are respectively arranged on the pipelines between the evaporation device 110 and the plurality of condensing devices so as to be used for regulating the pressure of the organic working media with different pressures to be consistent. The pressure regulating member may be configured as a working medium pump. For example, the pressure regulating member may pressurize the organic working fluid discharged from the condensing device.
The organic working media from different expansion pipelines can be subjected to pressure regulation through different pressure regulating members, and the pressure of the organic working media regulated by the pressure regulating members is kept consistent. The organic working medium with the consistent pressure regulation flows back to the evaporation device 110 to continuously exchange heat with a heat source. Thereby ensuring the normal operation of the organic working medium flow path. The plurality of pressure regulating members can respectively pressurize the organic working media with different pressures flowing out of the plurality of condensing devices, so that the pressure of the organic working media discharged from the plurality of pressure regulating members is kept consistent. The organic working medium with consistent pressure flows into the evaporation device 110 after converging.
Preferably, the plurality of pressure regulating members includes a first pressure regulating member 171, a second pressure regulating member 172, and a third pressure regulating member 173. The first pressure regulating member 171 is disposed between the first condensing device 141 and the evaporating device 110, the organic working fluid from the first condensing device 141 can enter the first pressure regulating member 171, and the first pressure regulating member 171 regulates the pressure of the organic working fluid from the first condensing device 141. The second pressure regulating member 172 is disposed between the second condensing unit 142 and the evaporating unit 110, the organic working fluid from the second condensing unit 142 can enter the second pressure regulating member 172, and the second pressure regulating member 172 regulates the pressure of the organic working fluid from the second condensing unit 142. The third pressure regulating member 173 is disposed between the third condensing device 143 and the evaporating device 110, the organic working fluid from the third condensing device 143 can enter the third pressure regulating member 173, and the third pressure regulating member 173 regulates the pressure of the organic working fluid from the third condensing device 143.
The pressure of the organic working medium adjusted by the first pressure adjusting member 171, the pressure of the organic working medium adjusted by the second pressure adjusting member 172 and the pressure of the organic working medium adjusted by the third pressure adjusting member 173 are all kept consistent. The pressure-regulated organic working medium flows back to the evaporation device 110 to exchange heat with a heat source.
The pressure of the organic working medium at the inlet of each pressure regulating member can correspond to the pressure of the working medium exhaust steam in the corresponding condensing device. The pressure of the organic working medium at the outlets of the pressure regulating members is kept consistent, and the outlets of the pressure regulating members can be respectively connected with the evaporation device 110 or combined and converged and then connected with the evaporation device 110.
According to the LNG cold energy cascade power generation system of the utility model, the LNG cold energy cascade power generation system comprises an evaporation device, an expander, a power generation device, a plurality of condensing devices and a plurality of pressure regulating members, the evaporation device comprises a heat source pipeline and a working medium pipeline, the evaporation device is used for carrying out heat exchange between a heat source in the heat source pipeline and an organic working medium in the working medium pipeline to form working medium steam, the expander is in transmission connection with the power generation device and is used for driving the power generation device to generate power, the expander comprises an expander inlet and a plurality of expander outlets, the expander inlet is communicated with the working medium pipeline of the evaporation device, so that the working medium steam from the evaporation device can enter the expander to form working medium exhaust steam with different pressures, the working medium exhaust steam with different pressures is respectively discharged from the plurality of expander outlets, the plurality of condensing devices are correspondingly arranged with the plurality of expander outlets, the plurality of condensing devices are connected in parallel between the expander and the evaporation device via the pipeline, and the plurality of condensing units are connected in series through LNG pipelines so that working medium exhaust steam with different pressures exchanges heat with LNG in the plurality of condensing units respectively to form organic working media with different pressures, and the plurality of pressure regulating members are arranged on the pipelines between the evaporating unit and the plurality of condensing units respectively so as to regulate the pressures of the organic working media with different pressures uniformly. Therefore, the LNG cold energy cascade power generation system can effectively utilize the constantly changing gasification temperature in the LNG gasification process, and the condensation curve of the dead steam of the working medium is matched with the gasification curve of the LNG by improving the temperature of the LNG at the outlet of the LNG pipeline, so that the utilization rate of the LNG cold energy is improved, the cold and heat loss in the heat exchange process is reduced, and the power generation power of the LNG cold energy cascade power generation system is further improved.
Preferably, the mass flow rate of the working medium steam at the expander inlet 124 is equal to the sum of the mass flow rates of the working medium exhaust steam at the plurality of expander outlets. According to the present scheme, the expander 120 reduces energy loss when doing work. FIG. 2 shows the condensation curve of the working medium exhaust steam and the vaporization curve of the LNG in the embodiment, wherein the condensation curve of the working medium exhaust steam is P1～PnThe lines shown in between are arranged in a step mode, and the gasification curve of the LNG is a smooth transition curve shown between L1 and L2.
Specifically, as described above, the working medium steam in the expander 120 may enter the first-stage rotating member to perform expansion work, and expand to a certain pressure to form working medium exhaust steam, a portion of the working medium exhaust steam is discharged from the first expander outlet 121, another portion of the working medium steam continues to enter the second-stage rotating member to perform expansion work, another portion of the working medium exhaust steam is discharged from the second expander outlet 122, another portion of the working medium steam continues to enter the third-stage rotating member to perform expansion work, and another portion of the working medium exhaust steam is discharged from the third expander outlet 123, and so on to the nth-stage rotating member.
The mass flow of the working fluid vapor entering the expander 120 via the expander inlet 124 is V. The pressure of the dead steam of the working medium discharged from the outlet 121 of the first expansion machine is P1The mass flow of the dead steam of the working medium discharged from the outlet 121 of the first expansion machine is V1. The pressure of the dead steam of the working medium discharged through the outlet 122 of the second expander is P2The mass flow of the dead steam of the working medium discharged through the outlet 122 of the second expander is V2. The pressure of the dead steam of the working medium discharged through the outlet 123 of the third expander is P3The mass flow of the dead steam of the working medium discharged from the outlet 123 of the third expander is V3. Warp beamThe pressure of the working medium exhaust steam discharged from the outlet of the nth expansion machine is PnThe mass flow of the dead steam of the working medium discharged from the outlet of the nth expansion machine is Vn。
Because the working medium steam sequentially acts in the expansion machine 120 and the working medium exhaust steam is respectively discharged through different expansion machine outlets, the pressure value P of the working medium exhaust steam discharged from the outlets of the plurality of expansion machines1>P2>P3>……>PnMass flow V of working medium exhaust steam discharged from outlets of a plurality of expansion machines1+V2+V3+……+VnV. Working medium steam enters the 1 st-stage rotating member to do work, then partial dead steam is discharged, and then enters the 2 nd-stage rotating member to continue to do work, and the mass flow of the working medium steam entering the 2 nd-stage rotating member can be V1'. Likewise, the mass flow of the working medium steam entering the 3 rd stage rotating member is V2', the mass flow rate of the working medium steam entering the nth stage rotating member is Vn-1', then the mass flow V of the working medium vapor entering the plurality of rotating membersn-1’＝Vn+Vn'. Therefore, the working medium steam can enter the expansion machine to do work respectively, so that power is generated respectively, and the power generation efficiency is improved.
The LNG cold energy cascade power generation system 100 of the embodiment can match the condensation curve of the working medium exhaust steam with the LNG gasification temperature curve, reduce the cold and heat loss in the heat exchange process, improve the utilization rate of the LNG cold energy, and further improve the power generation efficiency of the LNG cold energy cascade power generation system 100. Further, the LNG cold energy cascade power generation system can form n pressures P1～PnCompared with the working medium exhaust steam with single pressure, the working medium exhaust steam has the advantages that the output power of the expander 120 is improved, the power generation efficiency is improved, the cold energy utilization efficiency of LNG is improved, and the condition that the heat exchange cannot be realized due to the fact that the temperature of a condensation curve of the working medium exhaust steam is crossed with the temperature of an LNG gasification temperature curve is avoided.
Preferably, the mass flow rates of the working medium exhaust steam at the outlets of the multiple expanders can be equal or different. In an alternative embodiment, the mass flow of the working fluid exhaust steam at the outlet of the multiple expanders may be equal. ByThe power generation device can do work in a balanced manner and generate power stably. The mass flow of the working medium exhaust steam at the outlet 121 of the first expansion machine can be V1The mass flow of the dead steam of the working medium at the outlet 122 of the second expander can be V2The mass flow of the working medium exhaust steam at the outlet 123 of the third expansion machine can be V3The mass flow of the working medium exhaust steam at the outlet of the nth expansion machine can be Vn，V1＝V2＝V3＝……＝Vn。
In another alternative embodiment, the mass flow of the exhaust steam of the working fluid at the outlets of the plurality of expanders may not be equal. The mass flow of the working medium exhaust steam at the outlets of the multiple expansion machines can be different according to different heat exchange quantities of all sections of LNG, so that the utilization rate of cold energy of the LNG is effectively improved, and the power generation efficiency is improved.
For example, when the mass flow of LNG is VlngThe mass flow of the working medium exhaust steam at the outlet 121 of the first expansion machine can be V1The mass flow of the dead steam of the working medium at the outlet 122 of the second expander can be V2The mass flow of the working medium exhaust steam at the outlet 123 of the third expansion machine can be V3The mass flow of the working medium exhaust steam at the outlet of the nth expansion machine can be Vn，V1、V2、V3、……、VnThe LNG is respectively led into different condensing devices to exchange heat with working medium exhaust steam with different mass flow rates, so that the generating efficiency is highest. Of course, the flow rate of the exhaust steam of the working medium discharged from the outlets of the different expanders can be partially the same to meet the heat exchange requirements of different LNG, and the embodiment is not intended to be limited to this.
Further, fig. 2 shows a vaporization curve of LNG, where L1 is a coordinate point of LNG introduced into the nth condensing device (such as the third condensing device 143 of fig. 1), and L2 is a coordinate point of LNG discharged from the first condensing device 141. The temperature of the LNG introduced into the nth condensing unit is lower than that of the LNG discharged from the first condensing unit 141. The LNG introduced into the nth condensing unit has the lowest temperature, and the LNG discharged from the first condensing unit 141 has the highest temperature. The LNG of the LNG cold energy cascade power generation system 100 according to the present embodiment can form a smooth vaporization temperature curve between L1 and L2 because the temperature of LNG increases during the cold energy release process. The vaporization temperature of LNG refers to the temperature of LNG during the vaporization process, which varies.
Working medium exhaust steam with different pressures respectively enters different condensing devices through different pipelines. First pressure P discharged from the first expander outlet 1211The dead steam of the working medium enters the first condensing device 141 through the first expansion pipeline 151. Second pressure P discharged from second expander outlet 1222The dead steam of the working medium enters the second condensing device 142 through the second expansion pipeline 152. Third pressure P from third expander outlet 1233The dead steam of the working medium enters the third condensing device 143 through the third expansion pipeline 153. N pressure P discharged from outlet of n expandernThe working medium dead steam enters an nth condensing device through an nth expansion pipeline.
The first condensing device 141 is located downstream of the second condensing device 142 in the flow direction of LNG, the second condensing device 142 is located downstream of the third condensing device 143 in the flow direction of LNG, and so on to the nth condensing device. LNG flows from the nth condensing unit to the first condensing unit 141. The pressure of the working medium exhaust steam in the first condensing device 141 is greater than that of the working medium exhaust steam in the second condensing device 142, the pressure of the working medium exhaust steam in the second condensing device 142 is greater than that of the working medium exhaust steam in the third condensing device 143, and so on until the pressure of the working medium exhaust steam in the nth condensing device. That is, the pressure of the working medium exhaust steam in the first condensing unit 141 is the highest, and the pressure of the working medium exhaust steam in the nth condensing unit is the lowest. The pressure of the working medium exhaust steam of the plurality of condensing devices can be sequentially increased along the flow direction of the LNG. LNG can flow into the condensing device of the high-pressure working medium exhaust steam from the condensing device of the low-pressure working medium exhaust steam. The pressure of the LNG during the gasification process remains substantially constant. Therefore, different gasification temperatures of the LNG in each stage can be effectively utilized, the energy utilization rate is improved, and energy waste is reduced.
Likewise, the temperature of the working medium exhaust steam with different pressures is different. First temperature T discharged from first expander outlet 1211Working medium exhaust steam enters through a first expansion pipeline 151Into the first condensing unit 141. Second temperature T exiting second expander outlet 1222The dead steam of the working medium enters the second condensing device 142 through the second expansion pipeline 152. Third temperature T from third expander outlet 1233The dead steam of the working medium enters the third condensing device 143 through the third expansion pipeline 153. Nth temperature T discharged from outlet of nth expandernThe working medium dead steam enters an nth condensing device through an nth expansion pipeline.
The temperature of the working medium exhaust steam in the first condensing device 141 is higher than that of the working medium exhaust steam in the second condensing device 142, the temperature of the working medium exhaust steam in the second condensing device 142 is higher than that of the working medium exhaust steam in the third condensing device 143, and the rest is done up to the temperature of the working medium exhaust steam in the nth condensing device. That is, the temperature of the working medium exhaust steam in the first condensing unit 141 is the highest, and the temperature of the working medium exhaust steam in the nth condensing unit is the lowest. The temperature of the working medium exhaust steam of the plurality of condensing devices can be sequentially increased along the flow direction of the LNG. LNG can flow into the condensing device where high-temperature working medium exhaust steam is located from the condensing device where low-temperature working medium exhaust steam is located. Therefore, different gasification temperatures of the LNG in each stage can be effectively utilized, the energy utilization rate is improved, and energy waste is reduced.
The LNG gasification temperature curve is matched with the condensation curve of the working medium exhaust steam. With reference to FIG. 2, the condensing curve, P, of the exhaust steam of the working medium1～PnThe corresponding condensing temperature is gradually decreased. Referring to the LNG vaporization temperature profile shown in fig. 2, the temperature between L1 and L2 gradually increases. The energy absorbed by the LNG is equal to the sum of the energy released by the working medium exhaust steam discharged from the outlets of the plurality of expanders. Therefore, no heat loss exists in the process of releasing cold energy by the LNG, and the energy utilization rate is improved.
The utility model also provides a power generation method for foretell LNG cold energy step power generation system 100. As shown in fig. 3, the power generation method includes the steps of:
and selecting the components of the organic working medium according to the gasification temperature of the LNG and the temperature of the heat source.
The LNG cold energy cascade power generation system 100 includes a heat source pipeline 111, a working medium pipeline and an LNG pipeline, wherein a heat source is arranged in the heat source pipeline 111, and the heat source can be seawater, solar energy, air, hot water, steam, flue gas, circulating water or process wastewater. The working medium pipeline is provided with an organic working medium which can be a mixture of one or more of methane, ethane, propane, ethylene, propylene, tetrafluoroethane, ammonia and the like. LNG is arranged in the LNG pipeline.
The components of the organic working medium can be selected according to the LNG gasification temperature and the temperature of the heat source. The vaporization temperature of LNG refers to the temperature of LNG during the vaporization process, which varies. For example, the organic working fluid may be methane or a mixture of methane and ethane.
And matching the pressure of the working medium steam according to the temperature of the heat source.
The heat source in the heat source pipeline 111 and the organic working medium in the working medium pipeline can exchange heat in the evaporation device 110. The organic working medium can absorb the heat of the heat source to form working medium steam. Therefore, the pressure of different working medium steam can be matched according to different temperatures of the heat source.
And the pressure of the preset organic working medium of the plurality of condensing devices is respectively matched according to the gasification temperature of the LNG, so that the temperature of the organic working medium generated by the condensing devices is matched with the gasification temperature of the LNG.
LNG in the LNG pipeline can exchange heat with working medium exhaust steam in the condensing device. Organic working medium can be formed after the working medium exhaust steam is subjected to heat exchange. The working medium exhaust steam can be formed by expansion work of the expander 120. In order to enable the expander 120 to perform appropriate expansion work and enable the expander 120 to perform expansion work to form working medium exhaust steam with appropriate pressure. Therefore, the pressure of the organic working medium preset by the plurality of condensing devices needs to be matched in advance according to the gasification temperature of the LNG, so that the working medium dead steam is ensured to enter the condensing devices and can generate the organic working medium with the preset pressure.
The LNG cold energy cascade system comprises a plurality of condensing devices, and working medium exhaust steam with different pressures respectively enters different condensing devices so as to exchange heat with LNG. The LNG pipeline connects a plurality of condensing units together in series. LNG can exchange heat with working medium exhaust steam with different pressures in the plurality of condensing units in sequence, so that the working medium exhaust steam absorbs cold energy of the LNG to form an organic working medium. The temperature of the organic working medium can be matched with the gasification temperature of the LNG. Thereby, the utilization rate of the cold energy of the LNG can be improved.
The expander 120 is selected based on the pressure of the working medium vapor and the pressure of the predetermined organic working medium.
The expanders 120 of different models are selected according to the pressure of the working medium steam and the pressure of the preset organic working medium, so that the pressure value of the working medium exhaust steam discharged from the expander outlets of the expanders 120 is ensured to be in accordance with the preset pressure, and the pressure of the organic working medium discharged from the condensing device is further ensured to be in accordance with the preset value.
According to the utility model discloses a power generation method for foretell LNG cold energy step power generation system, power generation method includes the composition that selects organic working medium according to the gasification temperature of LNG and the temperature of heat source, matches the pressure of working medium steam according to the temperature of heat source, matches the pressure of the preset organic working medium of a plurality of condensing equipment respectively according to the gasification temperature of LNG for the temperature of organic working medium and the gasification temperature phase-match of LNG, select the expander according to the pressure of working medium steam and the pressure of the preset organic working medium. Therefore, the constantly-changing gasification temperature in the LNG gasification process can be effectively utilized, the utilization rate of LNG cold energy is improved, the cold and heat loss in the heat exchange process is reduced, and a proper expansion machine is selected.
The evaporation apparatus 110, the expander 120, the plurality of condensation apparatuses, and the plurality of pressure regulating members are connected together.
The evaporation apparatus 110, the expander 120, the plurality of condensation apparatuses, and the plurality of pressure regulating members may be connected together by piping. In the evaporation device 110, the heat source of the heat source pipeline 111 exchanges heat with the organic working medium in the working medium pipeline, and the organic working medium absorbs heat to form working medium steam. The evaporation pipeline 112 is communicated with the working medium pipeline of the evaporation device 110, and the working medium steam from the evaporation device 110 can enter the evaporation pipeline 112.
The expander 120 comprises an expander inlet 124, the working medium steam in the evaporation pipeline 112 enters the expander 120 through the expander inlet 124, and the working medium steam can expand in the expander 120 to do work, so as to drive the power generation device 130 to generate power.
The expander 120 may be an axial turbo expander, a centrifugal turbo expander, a radial turbo expander, or a screw expander. Therefore, the LNG cold energy cascade power generation system 100 can be applied to various expansion machines 120, and the application range is expanded.
The expander 120 comprises a plurality of expander outlets, working medium steam can do work in the expander 120 to form working medium exhaust steam with different pressures, and the working medium exhaust steam with different pressures can be discharged from the plurality of expander outlets with corresponding pressure grades respectively.
The outlets of the plurality of expanders respectively enter the plurality of condensing devices through the plurality of pipelines, and the plurality of condensing devices are connected in series through LNG pipelines.
The pressure grade preset by the condensing device corresponds to the pressure of the working medium exhaust steam. The working medium exhaust steam with different pressures respectively enters a plurality of condensing devices. LNG in the LNG pipeline can exchange heat with working medium exhaust steam with different pressures in different condensing units in sequence. The working medium exhaust steam absorbs LNG cold energy under corresponding pressure so as to be condensed into an organic working medium.
The organic working media with different pressures are respectively regulated in pressure by the pressure regulating members, and the pressure of the organic working media discharged by the pressure regulating members is kept consistent. The organic working medium with the consistent pressure regulation enters the evaporation device 110 again for recycling.
Unless defined otherwise, technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. Terms such as "part," "member," and the like, when used herein, can refer to either a single part or a combination of parts. Terms such as "mounted," "disposed," and the like, as used herein, may refer to one component as being directly attached to another component or one component as being attached to another component through intervening components. Features described herein in one embodiment may be applied to another embodiment, either alone or in combination with other features, unless the feature is otherwise inapplicable or otherwise stated in the other embodiment.
The present invention has been described in terms of the above embodiments, but it is to be understood that the above embodiments are for purposes of illustration and description only and are not intended to limit the invention to the described embodiments. Furthermore, it will be understood by those skilled in the art that the present invention is not limited to the above-described embodiments, and that many more modifications and variations can be made in accordance with the teachings of the present invention, all of which fall within the scope of the invention as claimed. The scope of the invention is defined by the appended claims and equivalents thereof.
Claims (9)
1. An LNG cold energy cascade power generation system, comprising:
the evaporation device comprises a working medium pipeline and is used for carrying out heat exchange on a heat source and an organic working medium in the working medium pipeline to form working medium steam;
the expansion machine comprises an expansion machine inlet and a plurality of expansion machine outlets, the expansion machine inlet is communicated with the working medium pipeline of the evaporation device, so that the working medium steam from the evaporation device can enter the expansion machine to form working medium exhaust steam with different pressures, and the working medium exhaust steam with different pressures is discharged from the plurality of expansion machine outlets respectively;
the power generation device is in transmission connection with the expansion machine so as to convert mechanical energy into electric energy;
the plurality of condensing devices are arranged corresponding to the outlets of the plurality of expanders, connected in parallel between the expanders and the evaporating devices through pipelines, and connected in series through LNG pipelines, so that the working medium exhaust steam with different pressures is subjected to heat exchange with LNG in the plurality of condensing devices respectively to form organic working media with different pressures; and
the pressure regulating members are respectively arranged on pipelines between the evaporation device and the condensing devices and used for adjusting the pressure of the organic working medium with different pressures to be consistent.
2. The LNG cold energy cascade power generation system of claim 1, wherein the expander further comprises a multi-stage rotating member, the working medium steam sequentially enters the multi-stage rotating member to expand and do work to form the working medium exhaust steam with different pressures, and the working medium exhaust steam from the multi-stage rotating member is discharged through the plurality of expander outlets respectively.
3. The LNG cold energy cascade power generation system of claim 2, wherein the mass flow of the working medium steam at the expander inlet is equal to the sum of the mass flows of the working medium exhaust steam at the plurality of expander outlets.
4. The LNG cold energy cascade power generation system of claim 3, wherein mass flow rates of the working medium exhaust steam at outlets of the plurality of expanders are equal or different.
5. The LNG cold energy cascade power generation system of claim 1, wherein the LNG absorbs energy equal to the sum of the energy released by the working medium exhaust steam discharged from the plurality of expander outlets.
6. The LNG cold energy cascade power generation system of claim 1, wherein the working medium exhaust steam of the plurality of condensing devices has a pressure and/or temperature that increases sequentially in a flow direction of LNG.
7. The LNG cold-powered cascade power generation system of claim 1, wherein the heat source is seawater, air, solar energy, geothermal energy, hot water, steam, flue gas, circulating water, or a process fluid.
8. The LNG cold energy cascade power generation system of claim 1, wherein the organic working fluid is a mixture of one or more of methane, ethane, propane, ethylene, propylene, tetrafluoroethane, and ammonia.
9. The LNG cold energy cascade power generation system of claim 1, wherein the expander is one or more of an axial flow turboexpander, a centrifugal turboexpander, a radial flow turboexpander, or a screw expander.
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