阅读说明：本技术 一种动力装置烟气二氧化碳减排系统 (Power device flue gas carbon dioxide emission reduction system ) 是由 舒歌群 孙瑞 田华 石凌峰 李晓雅 蔡金文 于 2020-11-17 设计创作，主要内容包括：本发明公开了一种动力装置烟气二氧化碳减排系统,主要包括第一预冷器、第二预冷器、凝华换热器、气液分离器、节流膨胀阀。本发明通过CO-2低温凝华相变原理实现烟气中CO-2的捕集,并将所捕集到的固态CO-2应用于CO-2气固两相制冷循环,利用固态CO-2升华相变潜热进行CO-2低温凝华捕集前预冷,从而实现低能耗CO-2凝华捕集。通过气液分离器分别得到气态和液态CO-2,气态CO-2用于与低温凝华捕集得到的固态CO-2混合形成气固两相制冷循环工质,液态CO-2通过增压泵提升压力后送往输运与储存环节。(The invention discloses a power plant flue gas carbon dioxide emission reduction system which mainly comprises a first precooler, a second precooler, a desublimation heat exchanger, a gas-liquid separator and a throttle expansion valve. The invention passes CO 2 Realizing CO in flue gas by low-temperature desublimation phase change principle 2 And capturing the captured solid CO 2 Application to CO 2 Gas-solid two-phase refrigeration cycle using solid CO 2 Sublimation of latent heat of phase change to CO 2 Precooling before low-temperature desublimation capture, thereby realizing low-energy-consumption CO 2 And (5) desublimation and trapping. Obtaining gaseous and liquid CO respectively through a gas-liquid separator 2 Gaseous CO 2 For collecting solid CO obtained by low-temperature desublimation 2 Mixing to form gas-solid two-phase refrigerating circulation working medium, liquid CO 2 The pressure is increased by a booster pump and then is conveyed to a transportation and storage link.)

1. The utility model provides a power device flue gas carbon dioxide emission reduction system which characterized in that: the system comprises a first precooler, a second precooler, a desublimation heat exchanger, a gas-liquid separator and a throttle expansion valve, wherein:

flue gas is introduced into the first precooler, and a heat exchange medium is introduced to absorb the heat of the flue gas so as to precool the flue gas for the first time; the first precooler is connected with the second precooler, so that the flue gas precooled for the first time in the first precooler enters the second precooler, and meanwhile, a heat exchange medium is introduced into the second precooler to absorb the heat of the flue gas so as to precool the flue gas for the second time; the second precooler is connected with the desublimation heat exchanger, so that the flue gas precooled secondarily by the second precooler enters the desublimation heat exchanger, the carbon dioxide in the flue gas is desublimated and separated to form solid carbon dioxide by the desublimation heat exchanger based on the low-temperature desublimation phase change principle, the carbon dioxide in the flue gas is collected, and meanwhile, low-temperature residual flue gas is obtained in the desublimation heat exchanger; the desublimation heat exchanger is connected with the first precooler, so that the low-temperature residual flue gas of the desublimation heat exchanger enters the first precooler as a heat exchange medium of the first precooler to carry out primary precooling on the flue gas introduced into the first precooler;

the gas-liquid separator and the desublimation heat exchanger are jointly connected with a second precooler, and the second precooler is connected with the throttle expansion valve; initially, gas carbon dioxide passes through a throttling expansion valve and a gas-liquid separator and then is mixed with solid carbon dioxide obtained by a desublimation heat exchanger to form a gas-solid two-phase fluid, the gas-solid two-phase fluid enters a second precooler to serve as a heat exchange medium of the second precooler to carry out secondary precooling on smoke, the solid carbon dioxide in the gas-solid two-phase fluid absorbs heat and becomes liquid, and the gas-liquid two-phase fluid is formed after heat exchange of the gas-solid two-phase fluid and flows out of the second precool; and the gas-liquid two-phase fluid enters a gas-liquid separator through a throttling expansion valve, the gas-liquid separator separates gaseous carbon dioxide and liquid carbon dioxide in the gas-liquid two-phase fluid, the liquid carbon dioxide flows out of the gas-liquid separator to an external collecting device, the gaseous carbon dioxide is mixed with new solid carbon dioxide obtained by a desublimation heat exchanger again to form new gas-solid two-phase fluid, the new gas-solid two-phase fluid enters a second precooler, and the formed gas-solid two-phase fluid is used as a heat exchange medium of the second precooler to carry out secondary precooling on the smoke in the sequential circulation.

2. The power plant flue gas carbon dioxide emission reduction system of claim 1, wherein: the system also comprises a capture system compressor, wherein the inlet of the capture system compressor is connected with the first precooler, the outlet of the capture system compressor is connected with the second precooler, and the capture system compressor compresses the flue gas flowing out of the first precooler and then sends the compressed flue gas into the second precooler.

3. The power plant flue gas carbon dioxide emission reduction system of claim 1, wherein: the low-temperature refrigerator is connected with the desublimation heat exchanger to form a refrigerant circulation loop, and the low-temperature refrigerant is introduced into the desublimation heat exchanger to ensure that carbon dioxide in the flue gas is desublimed into a solid state.

4. The power plant flue gas carbon dioxide emission reduction system of claim 1, wherein: the system also comprises a capture system expansion machine, wherein the inlet of the capture system expansion machine is connected with the desublimation heat exchanger, the outlet of the capture system expansion machine is connected with the first precooler, and the capture system expansion machine recovers partial pressure from the residual flue gas in the desublimation heat exchanger and then introduces the residual flue gas into the first precooler to serve as a heat exchange medium.

5. The power plant flue gas carbon dioxide emission reduction system of claim 1, wherein: the gas-liquid two-phase fluid which flows out of the second precooler enters the throttle expansion valve after the pressure of the gas-liquid two-phase fluid is raised by the compressor of the refrigeration system.

6. The power plant flue gas carbon dioxide emission reduction system of claim 5, wherein: the gas-liquid two-phase fluid enters the throttling expansion valve after being cooled by the gas cooler after the pressure of the compressor of the refrigeration system is increased.

Technical Field

The invention relates to the field of carbon dioxide desublimation capture systems, in particular to a power plant flue gas carbon dioxide emission reduction system.

Background

The global climate change problem caused by the artificial excessive emission of greenhouse gases is becoming more and more severe. Carbon dioxide (CO)₂) As a main component of greenhouse gases, there is a great deal of attention paid to the control of their production and emission. Carbon Capture, Utilization and Storage (CCUS) as CO₂The key technology of emission control becomes one of the major research fields of scholars at home and abroad.

Low temperature desublimated CO₂Trapped as CO₂One of the trapping technologies after combustion has the characteristics of high product recovery rate, high purity, environment-friendly trapping process and the like. However at low temperatures desublimation of CO₂In the trapping technology, the refrigeration energy consumption of the low-temperature cold source is the whole CO₂The main energy consumption source of the capture system. Furthermore, during the low temperature desublimation capture process, CO₂Directly captured in solid form, solid CO₂The corresponding low-temperature storage condition is strict and is not beneficial to subsequent CO₂And (5) a link of transportation, utilization and sealing storage. Before transport through the pipeline, the CO must be removed₂And (3) converting the solid into a supercritical fluid at about 35 ℃ and the pressure of 11-15 MPa. Therefore, how to realize CO₂Low energy consumption desublimation capture and post capture CO₂Is a major concern of this technology.

Mixing solid CO₂(Dry Ice) conversion to supercritical CO₂The traditional approach of (a) is to sublime dry ice at atmospheric pressure and use the multi-stage compression method currently applied in amine absorption capture processes. The major drawback of this approach is CO₂Energy input required for the compression process (conventional CO)₂The compression energy requirement is 90-120 kW h/t CO₂I.e. 324 to 432 kJ/kg CO₂) And an increase in the load of the auxiliary facilities. At the same time, the method is used for solid CO₂The latent heat value released during sublimation (about 570 kJ/kg) is not utilized properly.

In recent years, natural substance CO is used₂As working substancesThe refrigeration cycle of (a) has become mature in the field of refrigeration at low temperature and gradually realizes engineering application. Due to CO₂Unique triple point physical properties (-56.6 ℃, 0.518 MPa) based on solid CO₂Sublimating endothermic CO₂Gas-solid two-phase refrigeration cycle can be used to provide sub-CO₂Refrigeration temperature of triple point. At the same time, gaseous CO after sublimation₂Low energy consumption liquefaction can be realized through a throttling expansion device and a gas-liquid separation device in the refrigeration cycle. Due to the liquid CO under the same pressure increase₂The enthalpy increase is much less than in the gaseous state, i.e. less shaft work input is required for liquid state compression. Therefore, by adopting a pump with lower load to replace a gas compressor with higher energy demand, the compression energy consumption can be effectively reduced.

In conclusion, the CO is desublimated at low temperature₂Capturing the solid CO obtained₂Direct use for CO₂Gas-solid two-phase refrigeration and CO supply₂Part of refrigeration capacity required by low-temperature desublimation capture, and CO is pumped₂Compression to transport pressure, CO can be achieved₂Low energy consumption capture and compression.

Disclosure of Invention

The invention aims to provide a power plant flue gas carbon dioxide emission reduction system, which aims to solve the problems that a carbon dioxide desublimation capture system in flue gas in the prior art has high energy consumption and does not fully utilize energy generated by carbon dioxide state change in a capture process.

In order to achieve the purpose, the technical scheme adopted by the invention is as follows:

the utility model provides a power device flue gas carbon dioxide emission reduction system, includes first precooler, second precooler, desublimation heat exchanger, vapour and liquid separator, throttle expansion valve, wherein:

flue gas is introduced into the first precooler, and a heat exchange medium is introduced to absorb the heat of the flue gas so as to precool the flue gas for the first time; the first precooler is connected with the second precooler, so that the flue gas precooled for the first time in the first precooler enters the second precooler, and meanwhile, a heat exchange medium is introduced into the second precooler to absorb the heat of the flue gas so as to precool the flue gas for the second time; the second precooler is connected with the desublimation heat exchanger, so that the flue gas precooled secondarily by the second precooler enters the desublimation heat exchanger, the carbon dioxide in the flue gas is desublimated and separated to form solid carbon dioxide by the desublimation heat exchanger based on the low-temperature desublimation phase change principle, the carbon dioxide in the flue gas is collected, and meanwhile, low-temperature residual flue gas is obtained in the desublimation heat exchanger; the desublimation heat exchanger is connected with the first precooler, so that the low-temperature residual flue gas of the desublimation heat exchanger enters the first precooler as a heat exchange medium of the first precooler to carry out primary precooling on the flue gas introduced into the first precooler;

the gas-liquid separator and the desublimation heat exchanger are jointly connected with a second precooler, and the second precooler is connected with the throttle expansion valve; initially, gas carbon dioxide passes through a throttling expansion valve and a gas-liquid separator and then is mixed with solid carbon dioxide obtained by a desublimation heat exchanger to form a gas-solid two-phase fluid, the gas-solid two-phase fluid enters a second precooler to serve as a heat exchange medium of the second precooler to carry out secondary precooling on smoke, the solid carbon dioxide in the gas-solid two-phase fluid absorbs heat and becomes liquid, and the gas-liquid two-phase fluid is formed after heat exchange of the gas-solid two-phase fluid and flows out of the second precool; and the gas-liquid two-phase fluid enters a gas-liquid separator through a throttling expansion valve, the gas-liquid separator separates gaseous carbon dioxide and liquid carbon dioxide in the gas-liquid two-phase fluid, the liquid carbon dioxide flows out of the gas-liquid separator to an external collecting device, the gaseous carbon dioxide is mixed with new solid carbon dioxide obtained by a desublimation heat exchanger again to form new gas-solid two-phase fluid, the new gas-solid two-phase fluid enters a second precooler, and the formed gas-solid two-phase fluid is used as a heat exchange medium of the second precooler to carry out secondary precooling on the smoke in the sequential circulation.

The utility model provides a power device flue gas carbon dioxide emission reduction system still includes the entrapment system compressor, and the entrapment system compressor inlet is connected with first precooler, and the entrapment system compressor export is connected with the second precooler, sends into the second precooler after being compressed with the flue gas that the first precooler flows by the entrapment system compressor.

In the system for reducing the emission of the carbon dioxide in the flue gas of the power plant, the desublimation heat exchanger is provided with a low-temperature refrigerator, the low-temperature refrigerator is connected with the desublimation heat exchanger to form a refrigerant circulation loop, and the low-temperature refrigerant is introduced into the desublimation heat exchanger to desublimate the carbon dioxide in the flue gas into a solid state.

The utility model provides a power device flue gas carbon dioxide emission reduction system still includes the entrapment system expander, and the import of entrapment system expander is connected with the desublimation heat exchanger, and the export of entrapment system expander is connected with first precooler, is let in the remaining flue gas in the desublimation heat exchanger as heat transfer medium in the part pressure back is retrieved from the remaining flue gas by the entrapment system expander.

The system for reducing emission of carbon dioxide in flue gas of the power device further comprises a refrigeration system compressor, wherein an inlet of the refrigeration system compressor is connected with the second precooler, an outlet of the refrigeration system compressor is connected with the throttle expansion valve, and a gas-liquid two-phase fluid flowing out of the second precooler enters the throttle expansion valve after the pressure of the gas-liquid two-phase fluid is increased by the refrigeration system compressor.

The system for reducing emission of carbon dioxide in flue gas of the power plant further comprises a gas cooler, wherein an inlet of the gas cooler is connected with an outlet of a compressor of the refrigeration system, an outlet of the gas cooler is connected with the throttle expansion valve, and a gas-liquid two-phase fluid is subjected to pressure increase by the compressor of the refrigeration system, then is cooled by the gas cooler and then enters the throttle expansion valve.

According to the invention, the capture of carbon dioxide in flue gas is realized by adopting a low-temperature desublimation phase change principle, and the captured carbon dioxide is applied to carbon dioxide gas-solid two-phase refrigeration cycle, so that secondary precooling before low-temperature desublimation capture of carbon dioxide is realized, and the energy consumption of low-temperature desublimation capture is reduced. Gaseous carbon dioxide and liquid carbon dioxide are respectively obtained through a gas-liquid separator, the gaseous carbon dioxide is used for being mixed with solid carbon dioxide obtained by low-temperature desublimation capture to form a gas-solid two-phase fluid so as to realize secondary precooling before low-temperature desublimation capture of flue gas, and the liquid carbon dioxide is conveyed to a transportation and storage link through a booster pump.

The working process of the invention is as follows: the method comprises the steps of firstly introducing flue gas from a power device into a first precooler, condensing and separating moisture in the flue gas by using the cold energy of the residual flue gas after trapping, and simultaneously realizing primary precooling before compression of the flue gas. The flue gas compressed by the compressor of the trapping system enters a second precooler to exchange heat with gas-solid two-phase fluid in the gas-solid refrigeration cycle for cooling, and then is further cooled by a desublimation heat exchanger to realize carbon dioxide desublimation and separation. The trapped solid carbon dioxide is mixed with the gaseous carbon dioxide obtained by the gas-liquid separator to form a gas-solid two-phase fluid, the gas-solid two-phase fluid is gasified in a second precooler to absorb heat to obtain refrigerating capacity so as to realize secondary precooling before desublimation, and the gas-solid two-phase fluid forms a gas-liquid two-phase fluid after heat exchange. The gas-liquid two-phase fluid is subjected to compression, cooling and expansion processes, and the liquid carbon dioxide is separated in the gas-liquid separator and then sent to a subsequent carbon dioxide collecting device for transportation and utilization.

The invention has the beneficial effects that:

the invention integrates the carbon dioxide low-temperature desublimation capturing system and the carbon dioxide gas-solid refrigeration system, realizes the capturing of the carbon dioxide with low energy consumption, and is beneficial to the engineering application of capturing, utilizing and transporting the carbon dioxide. Firstly, the carbon dioxide is directly captured in a solid state form, and the capturing efficiency and the purity are high; secondly, the captured solid carbon dioxide is used for providing refrigerating capacity to reduce capturing energy consumption and realize effective utilization of the captured carbon dioxide; thirdly, the captured solid carbon dioxide is converted into a liquid form convenient for transportation and storage through carbon dioxide gas-solid refrigeration circulation, so that the compression power consumption of the captured gaseous carbon dioxide to transportation pressure through multi-stage compression in the desublimation capturing technology in the prior art is avoided, and the energy-saving and emission-reducing benefits and the application prospect are remarkable.

Drawings

FIG. 1 is a block diagram of the system of the present invention.

Detailed Description

The invention is further illustrated with reference to the following figures and examples.

As shown in fig. 1, the flue gas carbon dioxide emission reduction system of a power plant of the present invention comprises a first precooler 1, a capture system compressor 2, a second precooler 3, a desublimation heat exchanger 4, a cryocooler 5 configured with the desublimation heat exchanger, a capture system expander 6, a refrigeration system compressor 7, a gas cooler 8, a throttle expansion valve 9, a gas-liquid separator 10, and a booster pump 11, wherein:

the first precooler 1 and the second precooler 3 are respectively provided with a main channel and a heat exchange medium channel, the main channel is used for introducing flue gas, and the heat exchange medium channel is used for introducing a heat exchange medium. Flue gas is introduced into a main channel inlet of the first preheater 1, a main channel outlet of the first preheater is connected with an inlet of the capture system compressor 2, and an outlet of the capture system compressor 2 is connected with a main channel inlet of the second precooler 3.

The desublimation heat exchanger 4 is provided with a main channel and a refrigerant channel, wherein the main channel is used for introducing flue gas, and two ends of the refrigerant channel are respectively connected with an inlet and an outlet of the low-temperature refrigerator 5 to form a refrigerant circulation loop. The outlet of the main channel of the second precooler 3 is connected with the inlet of the main channel of the desublimation heat exchanger 4, the outlet of the main channel of the desublimation heat exchanger 4 is connected with the inlet of the capture system expansion machine 6, and the outlet of the capture system expansion machine 6 is connected with the inlet of the heat exchange medium channel of the first precooler 1.

Flue gas is introduced into a main channel of the first precooler 1, meanwhile, a heat exchange medium is introduced into a heat exchange medium channel to absorb heat of the flue gas so as to primarily precool the flue gas, the flue gas after primary precooling is compressed by the capture system compressor 2 and then enters a main channel of the second precooler 3, and meanwhile, the heat exchange medium is introduced into a heat exchange medium channel of the second precooler 3 so as to secondarily precool the flue gas. Flue gas precooled for the second time by the second precooler 3 enters a main channel of the desublimation heat exchanger 4, a refrigerating machine channel of the desublimation heat exchanger 4 is simultaneously introduced with a refrigerating agent output by the low-temperature refrigerating machine 5, the desublimation heat exchanger 4 causes carbon dioxide in the flue gas to be desublimated and separated to form solid carbon dioxide, the carbon dioxide in the flue gas is collected, and simultaneously, low-temperature residual flue gas is obtained in the desublimation heat exchanger 4. The low-temperature residual flue gas of the desublimation heat exchanger 4 is sent into a heat exchange medium channel of the first precooler 1 after partial pressure is recovered by the capture system expander 6, and is used as a heat exchange medium of the first precooler 1 to carry out primary precooling on the flue gas introduced into the first precooler 1. The capture of carbon dioxide in the flue gas and the utilization of the cold energy of the residual flue gas are formed.

An outlet of a heat exchange medium channel of the second precooler 3 is connected with an inlet of a refrigerating system compressor 7, an outlet of the refrigerating system compressor 7 is connected with an inlet of a gas cooler 8, an outlet of the gas cooler 8 is connected with an inlet of a throttle expansion valve 9, an outlet of the throttle expansion valve 9 is connected with an inlet at the lower part of a gas-liquid separator 10, a liquid outlet at one side of the gas-liquid separator 10 is connected with an inlet of a booster pump 11, and an outlet of the booster pump 11 is connected with an external collecting device. The desublimation heat exchanger 4 is provided with a solid outlet for flowing out solid carbon dioxide, and the upper part of the gas-liquid separator 10 is provided with a gas outlet which is converged with the solid outlet of the desublimation heat exchanger 4 through a pipeline and then connected with the heat exchange medium inlet of the second precooler 3.

The throttling expansion valve 9 initially introduces gaseous carbon dioxide, the gaseous carbon dioxide initially passes through the throttling expansion valve 9 and the gas-liquid separator 10 and then is mixed with the solid carbon dioxide obtained by the desublimation heat exchanger 4 to form a gas-solid two-phase fluid, the gas-solid two-phase fluid enters the heat exchange medium channel of the second precooler 3 and is used as the heat exchange medium of the second precooler 3 to secondarily precool the flue gas, the solid carbon dioxide in the gas-solid two-phase fluid absorbs heat and becomes liquid, and the gas-liquid two-phase fluid is formed after heat exchange of the gas-solid two-phase fluid and flows out of the second. The gas-liquid two-phase fluid enters a gas cooler 8 for cooling after the pressure of the gas-liquid two-phase fluid is increased by a compressor 7 of the refrigeration system, then enters a throttle expansion valve 9 for throttling expansion again and then enters a gas-liquid separator 10, the gas-liquid separator 10 separates gaseous carbon dioxide and liquid carbon dioxide in the gas-liquid two-phase fluid, the liquid carbon dioxide enters a booster pump 11 from the gas-liquid separator 10 and then is conveyed to an external collection device through the booster pump 11, the gaseous carbon dioxide is mixed with new solid carbon dioxide obtained by a desublimation heat exchanger 4 again to form new gas-solid two-phase fluid which enters a second precooler 3, and the formed gas-solid two-phase fluid is used as a heat exchange medium of the second precooler 3 for carrying out. The above forms a circulation process of the heat exchange medium in the second precooler 3.

In the invention, the flue gas is firstly introduced into the first precooler 1, the cold energy of the residual flue gas after being collected is utilized to condense and separate the moisture in the flue gas, and the precooling before the compression of the flue gas is realized. The flue gas compressed by the compressor 2 of the trapping system enters a second precooler 3 to exchange heat with the gas-solid two-phase fluid for cooling, and then is further cooled and cooled in a desublimation heat exchanger 4 through cooling heat exchange with a low-temperature refrigerator 5, so that the desublimation and separation of carbon dioxide in the flue gas are realized. And the residual flue gas after being trapped is introduced into the first precooler 1 as a medium heat exchange medium to exchange heat with newly introduced flue gas after part of pressure energy is recovered by the expansion machine 6 of the trapping system, so that the cold energy recycling of the residual flue gas is realized.

The solid carbon dioxide obtained by low-temperature desublimation and trapping is mixed with the gaseous carbon dioxide obtained in the throttling expansion process of the throttling expansion valve 9 in the refrigeration cycle to form a gas-solid two-phase fluid, the gas-solid two-phase fluid is sublimated and absorbs heat in the second precooler 3 to realize secondary precooling of the flue gas before the desublimation and trapping of the carbon dioxide in the flue gas, and the solid carbon dioxide in the gas-solid two-phase fluid absorbs heat and becomes a liquid state, so that the gas-solid two-phase fluid becomes. The gas-liquid two-phase fluid is subjected to pressure increase by a compressor 7 of the refrigeration system, then enters a gas cooler 8 for cooling, and then enters a gas-liquid separator 10 through throttling expansion by a throttling expansion valve 9. And separating the gaseous carbon dioxide and the liquid carbon dioxide in the gas-liquid two-phase fluid in the gas-liquid separator 10, wherein the gaseous carbon dioxide and the liquid carbon dioxide are respectively obtained at the upper part and the lower part of the gas-liquid separator 10, the gaseous carbon dioxide is used for being mixed with the solid carbon dioxide obtained by low-temperature desublimation and capture of the desublimation heat exchanger 4 to form a gas-solid two-phase fluid, and the liquid carbon dioxide is sent to a subsequent carbon dioxide collecting device for transportation and storage after the pressure of the liquid carbon.

The embodiments of the present invention are described only for the preferred embodiments of the present invention, and not for the limitation of the concept and scope of the present invention, and various modifications and improvements made to the technical solution of the present invention by those skilled in the art without departing from the design concept of the present invention shall fall into the protection scope of the present invention, and the technical content of the present invention which is claimed is fully set forth in the claims.