Wet flue gas decarburization method and apparatus

Abstract

The invention relates to the technical field of CO2 preparation, and discloses a wet flue gas decarburization method and equipment, and the wet flue gas decarburization method comprises the following steps: 1) washing hot flue gas to remove water-soluble impurities; 2) contacting the washed flue gas with a solvent to obtain a rich solution absorbing CO2; 3) carrying out steam stripping desorption on the rich solution to obtain CO2 and a barren solution; wherein the flue gas heat of the hot flue gas before water washing in the step 1) and the heat of the discharged material in the step 3) are collected, and the two streams of heat are used for steam stripping desorption in the step 3). The method has the advantages that the energy consumption is reduced, and the CO2 preparation cost is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of CO2 preparation, and in particular to a method and equipment for wet flue gas decarbonization. Background Art

[0002] The impact of global warming caused by greenhouse gases on human survival and development is becoming increasingly significant. Reducing CO2 emissions has become a key consensus and important measure to address global climate change. In the face of severe climate change issues, reducing CO2 and other greenhouse gas emissions and preventing global warming is a strategic issue related to the survival and reproduction of all mankind.

[0003] The distribution of carbon emissions in various parts of my country in 2019 is as follows Figure 3 my country's carbon emissions mainly come from CO2 emitted from energy consumption and industrial processes. Among them, carbon emissions from energy consumption mainly come from the combustion of fossil fuels, and carbon emissions from industrial processes mainly come from hydrogen production.

[0004] In view of the sources of carbon emissions in my country, carbon neutrality should be achieved through the following aspects:

[0005] 1. Realize energy structure transformation and replace fossil fuels with clean energy such as nuclear energy. China may need to adjust its primary energy structure from the current 85% fossil fuels to 85% clean energy.

[0006] 2. Find new ways to produce hydrogen and combine it with the use of clean energy to achieve decarbonization of the hydrogen production process.

[0007] 3. Develop carbon sinks and carbon capture, utilization and storage technologies.

[0008] At present, my country's carbon quota is a mechanism of free allocation and spot trading. my country's energy consumption per 10,000 yuan of GDP will drop by 13.5% between 2021 and 2025, so the carbon quota will be further tightened in the future. As the carbon emission market matures, the price of carbon trading will reach 300-500 yuan / ton of CO2. For high-energy-consuming enterprises, the excess carbon emissions significantly increase production costs, so they can only eliminate the original energy-consuming old technology and develop new technology or capture the CO2 that exceeds the carbon quota through carbon capture technology.

[0009] In the next 20 years, my country's energy structure is not expected to change much. Therefore, large-scale carbon capture, utilization and storage (CCUS) is the only solution that can be applied to the major heavy industrial facilities that are most difficult to reduce emissions in the next 20-30 years to achieve significant and direct emission reductions.

[0010] In terms of CO2 utilization, the main ways to use CO2 include enhanced oil recovery, facility agriculture, chemical conversion and food processing. According to surveys, the amount of CO2 that can be used for enhanced oil recovery is expected to exceed 40 million tons / year, and the annual oil production of CO2 flooding can reach tens of millions of tons. CO2 has great potential for EOR. Facility agriculture develops the carbon sink function of crops by increasing the application of carbon dioxide gas fertilizer. The carbon absorption rate of crops is about 0.007t / (m -2 ·a -1 ), if facility agriculture is used to capture 100,000 tCO2 per year, the required crop area is about 30 km 2 , that is, 40,000-50,000 mu. In 2012, my country's facility agriculture area was 57.96 million mu, accounting for more than 85% of the world's total area, and the maximum usable CO2 reached 100 million tons / year. However, due to the wide distribution of facility agriculture, the crop area required for a conventional scale carbon capture project is large, making it difficult to achieve larger-scale CO2 utilization. The total CO2 utilization for chemical conversion is currently about 250,000 tons, and it is still in the pilot stage. CO2 used in food processing is also very small.

[0011] In summary, EOR is the only way to achieve large-scale CO2 utilization. Combining CCS with EOR can achieve large-scale carbon capture and utilization. However, the current high cost of carbon capture is still a major factor affecting the large-scale promotion of CCS-EOR technology. Summary of the invention

[0012] The purpose of the present invention is to overcome the problems of high energy consumption and overall cost of CO2 capture technology in the prior art, and to provide a method and equipment for wet flue gas decarbonization, which has the advantages of saving energy consumption and reducing the cost of CO2 production.

[0013] In order to achieve the above object, the present invention provides a method for wet flue gas decarbonization, which comprises the following steps:

[0014] 1) Wash the hot flue gas with water to remove water-soluble impurities;

[0015] 2) contacting the washed flue gas with a solvent to obtain a rich liquid that absorbs CO2;

[0016] 3) stripping and desorbing the rich liquid to obtain CO2 and lean liquid;

[0017] The heat of the hot flue gas before water washing in step 1) is collected and used for steam stripping and desorption in step 3).

[0018] In some embodiments of the present invention, the method further comprises: collecting heat of a portion of the solution vapor and CO2 in step 3) for use in the stripping desorption in step 3).

[0019] In some embodiments of the present invention, the hot flue gas comes from at least one of coal boiler tail gas, natural gas boiler tail gas or oil boiler tail gas.

[0020] In some embodiments of the present invention, the composition of the hot flue gas includes: N2, CO2, H2O, O2, SO2, NO x , dust and oil.

[0021] In some embodiments of the present invention, the temperature of the hot flue gas is 80-250°C.

[0022] In some embodiments of the present invention, the flue gas temperature after water washing in step 2) is ≤50°C.

[0023] In some embodiments of the present invention, water-soluble impurities include SO2, NO x , at least one of dust and oil.

[0024] In some embodiments of the present invention, the solvent includes at least one of a monoethanolamine aqueous solution, a diethanolamine aqueous solution or a methyldiethanolamine aqueous solution.

[0025] In some embodiments of the present invention, the contact conditions in step 2) include: temperature range 40-50° C., normal pressure.

[0026] In some embodiments of the present invention, the conditions for stripping and desorption in step 3) include: a temperature range of 100-130° C. and a pressure range of 0.1-0.2 MPa.

[0027] In some embodiments of the present invention, the lean liquid in step 3) is returned to step 2) to contact with the flue gas after water washing to absorb CO2.

[0028] Another aspect of the present invention provides a device for wet flue gas decarbonization, the device for wet flue gas decarbonization comprising:

[0029] A water washing unit, connected to the flue gas feed pipe, is used to wash the hot flue gas with water to remove water-soluble impurities;

[0030] An absorption unit, connected to the water washing unit, for contacting the flue gas after water washing with a solvent, so that the solvent absorbs CO2 in the flue gas to form a rich liquid;

[0031] A desorption unit, connected to the absorption unit and comprising a stripping section, for stripping and desorbing the rich liquid to obtain CO2 and a lean liquid;

[0032] A heat circulation unit is used to collect the flue gas heat of the hot flue gas in the flue gas feeding pipe and provide it to the stripping part.

[0033] In some embodiments of the present invention, the heat circulation unit comprises a first heat exchange part and a second heat exchange part which are connected to each other, wherein the first heat exchange part is used to collect the flue gas heat of the hot flue gas in the flue gas feed pipe, and the second heat exchange part is used to provide the flue gas heat collected by the first heat exchange part to the stripping part.

[0034] In some embodiments of the present invention, the circulation unit also includes a third heat exchange part, which is used to collect the heat of the discharge material in the desorption unit. The third heat exchange part is connected to the second heat exchange part and is used to provide the heat of the discharge material to the stripping part.

[0035] Through the above technical scheme, the present invention integrates the cooling and heating requirements in the wet decarbonization process, uses the heat of the hot flue gas as the heat source, and further uses the heat of the hot flue gas and the heat of the discharge material of the desorption tower as the heat source, thereby saving energy consumption and reducing the production cost of CO2. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is a structural schematic diagram of a device for wet flue gas decarbonization according to a specific embodiment of the present invention;

[0037] Figure 2 It is a flow chart of Comparative Example 1 of the present invention;

[0038] Figure 3 This is the distribution of China’s carbon emissions in 2019.

[0039] Description of Reference Numerals

[0040] 1 water washing tower; 11 flue gas feed pipe; 12 washing water feed pipe; 2 absorption tower; 21 solvent feed pipe; 3 desorption tower; 31 desorption section; 32 stripping section; 33 CO2 product gas discharge pipe; 4 production pipe; 5 first heat exchanger; 6 third heat exchanger; 7 reboiler; 8 separation tank; 9 heat pump compressor. DETAILED DESCRIPTION

[0041] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0042] In the present invention, unless otherwise specified, directional words such as "up, down, left and right" used generally refer to the up, down, left and right shown in the reference drawings; "inside and outside" refer to the inside and outside relative to the outline of each component itself, and unless otherwise specified, the "top" of a container refers to the position of 0-30% from top to bottom of the container; the "upper part" of a container refers to the position of 0-50% from top to bottom of the container; the "lower part" of a container refers to the position of 0-50% from bottom to top of the container, and the "bottom" of a container refers to the position of 0-30% from bottom to top of the container.

[0043] In CCS technology, post-combustion flue gas absorption is still the most important and simplest method. Among them, chemical absorption occupies a dominant position. Chemical absorption methods mainly include hot potash method, ammonia method, alcohol amine method, etc. Their advantages and disadvantages and industrial application examples are shown in Table 1 below.

[0044] Table 1: Comparison and industrial examples of several decarbonization methods

[0045]

[0046]

[0047] The total cost of CO2 capture technology is relatively high, of which CO2 capture and separation accounts for about 70-80% of the total CCS cost. Therefore, reducing the cost of CO2 capture and separation is of great significance. According to the analysis of the cost of the absorption method, the high energy consumption of CO2 desorption is the main reason for the high cost of the absorption method. Among the desorption energy consumption, the latent heat of water evaporation and the sensible heat of absorbent heating account for 40-50% of the total desorption energy consumption. Therefore, in order to meet the needs of low-cost and high-efficiency separation of CO2, it is necessary to develop a low-energy flue gas decarbonization process.

[0048] In order to solve the above problems, the present invention discloses a method for wet flue gas decarbonization, which comprises the following steps:

[0049] 1) Wash the hot flue gas with water to remove water-soluble impurities;

[0050] 2) contacting the washed flue gas with a solvent to obtain a rich liquid that absorbs CO2;

[0051] 3) Stripping and desorbing the rich liquid to obtain CO2 and lean liquid;

[0052] The heat of the hot flue gas before water washing in step 1) is collected and used for steam stripping and desorption in step 3).

[0053] The present invention integrates the cooling and heating requirements in the wet decarbonization process and uses the heat of the hot flue gas as a heat source, thereby saving energy consumption and reducing the production cost of CO2.

[0054] In order to further save energy consumption and cost, the method of the present invention further comprises: collecting the heat of the solution vapor and CO2 in step 3) for use in the stripping desorption in step 3).

[0055] In some embodiments of the present invention, the hot flue gas comes from at least one of coal boiler tail gas, natural gas boiler tail gas or oil boiler tail gas.

[0056] In some embodiments of the present invention, the composition of the hot flue gas includes: N2, CO2, H2O, O2, SO2, NO x , dust and oil.

[0057] In some embodiments of the present invention, the temperature of the hot flue gas is 80-250°C.

[0058] In some embodiments of the present invention, the flue gas temperature after water washing in step 2) is ≤50°C.

[0059] In some embodiments of the present invention, the water-soluble impurities in step 1) include SO2, NO x , at least one of dust and oil. The method for treating water-soluble impurities in the present invention is selected according to the type of impurities. The present invention will not go into details and will only take the embodiments as examples.

[0060] In some embodiments of the present invention, the solvent in step 2) includes at least one of a monoethanolamine aqueous solution, a diethanolamine aqueous solution or a methyldiethanolamine aqueous solution. The embodiments of the present invention only use a monoethanolamine aqueous solution with a mass concentration of 20% as an example to illustrate the advantages of the present invention, but the present invention is not limited to this.

[0061] In some embodiments of the present invention, the contact conditions in step 2) include: a temperature range of 40-50° C. and normal pressure. In the present invention, the flue gas after water washing is contacted with the solvent by one of tray washing, packing washing, pipe jet washing, annular seam washing and bubbling washing in the prior art, which will not be described in detail in the present invention.

[0062] In some embodiments of the present invention, the conditions for stripping and desorption in step 3) include: a temperature range of 100-130° C. and a pressure range of 0.1-0.2 MPa.

[0063] In some embodiments of the present invention, the lean liquid in step 3) is returned to step 2) to contact with the flue gas after water washing to absorb CO2.

[0064] The second aspect of the present invention discloses a device for wet flue gas decarbonization, the device for wet flue gas decarbonization comprising:

[0065] A water washing unit, connected to the flue gas feed pipe 11, is used to wash the hot flue gas with water to remove water-soluble impurities;

[0066] The absorption unit is connected to the water washing unit and is used to contact the flue gas after water washing with the solvent, so that the solvent absorbs CO2 in the flue gas to form a rich liquid;

[0067] A desorption unit, connected to the absorption unit and comprising a stripping section 32, for stripping and desorbing the rich liquid to obtain CO2 and a lean liquid;

[0068] The heat circulation unit is used to collect the flue gas heat of the hot flue gas in the flue gas feeding pipe and provide the flue gas heat to the stripping part 32.

[0069] The wet flue gas decarbonization equipment of the present invention is intended to integrate the cooling and heating requirements in the current wet decarbonization process, and use the heat of the hot flue gas as the heat source of the stripping section 32, thereby saving energy consumption and reducing the production cost of CO2.

[0070] To further save energy consumption and cost, in some embodiments of the present invention, the heat circulation unit includes a first heat exchange part and a second heat exchange part that are connected to each other, wherein the first heat exchange part is used to collect the flue gas heat of the hot flue gas in the flue gas feed pipe, and the second heat exchange part is used to provide the flue gas heat collected by the first heat exchange part to the stripping part 32.

[0071] In order to further save energy consumption and cost, in some embodiments of the present invention, the circulation unit also includes a third heat exchange part, which is used to collect the heat of the discharge material in the desorption unit (for example, the heat of the desorbed CO2 and the heat of the solution vapor). The third heat exchange part is connected to the second heat exchange part and is used to provide the heat of the discharge material to the stripping part 32.

[0072] In some embodiments of the present invention, Figure 1 As shown, the water washing unit includes a water washing tower 1, which is connected to a flue gas feed pipe 11 and a washing water feed pipe 12; further, the flue gas feed pipe 11 is connected to the lower part of the water washing tower 1, and the outlet of the washing water feed pipe 12 is connected to the upper part of the water washing tower 1, so that the washing water fed by the washing water feed pipe 12 and the hot flue gas fed by the flue gas feed pipe 11 can be in countercurrent contact.

[0073] In order to further save energy consumption and cost, in some embodiments of the present invention, it is more preferred that the washing water feed pipe 12 is connected to the bottom of the water washing tower 1 and is provided with a delivery pump, so as to realize the circulation of the washing water falling to the bottom of the water washing tower 1 back to the upper part of the water washing tower 1. The water washing tower in the present invention also includes some conventional settings in the prior art, such as a sewage treatment device, a sprayer or valve for dispersing the washing water, etc. The present invention has no special requirements for this and will not be repeated.

[0074] In some embodiments of the present invention, the absorption unit includes an absorption tower 2, which is connected to the water washing tower 1 and the solvent feed pipe 21. The solvent feed pipe 21 is used to introduce a solvent for absorbing carbon dioxide into the absorption tower 2, and make the solvent contact with the flue gas after water washing in countercurrent to obtain a rich liquid that absorbs CO2; in the present invention, in order to achieve countercurrent contact between the solvent and the flue gas after water washing, the lower part of the absorption tower 2 can be connected to the top of the water washing tower 1, and the flue gas is introduced into the absorption tower 2. The solvent feed pipe 21 can be connected to the upper part of the absorption tower, and the solvent from top to bottom contacts the flue gas from bottom to top. The solvent absorbs CO2 in the flue gas, and the flue gas that cannot be absorbed becomes exhaust gas, which is discharged from the exhaust gas outlet opened at the top of the absorption tower 2. The present invention has no special requirements for the absorption tower. For example, the exhaust gas treatment device in the prior art can be connected to the top exhaust outlet, and the exhaust gas is discharged into the atmosphere after the exhaust gas is treated to meet the emission standards. For example, a sprayer for dispersing the solvent can be set in the absorption tower, which will not be repeated here.

[0075] In some embodiments of the present invention, the desorption unit comprises a desorption tower 3, such as Figure 1 As shown, the desorption tower 3 can be a conventional desorption tower (or regeneration tower), including a connected desorption section 31 and a stripping section 32, the desorption section 31 is connected to the absorption tower 2, the stripping section 32 is used to provide steam for the desorption section 31 and make the rich liquid from the absorption tower 2 countercurrently contact with the steam (such as water vapor) to desorb and obtain lean liquid and CO2; in the present invention, in order to achieve countercurrent contact between steam and rich liquid, the stripping section 32 is located at the lower part of the desorption tower 3, the desorption section 31 is located above the stripping section 32 and the top is connected to the bottom of the absorption tower 2 so that the rich liquid enters the tower from top to bottom, the desorption section 31 is connected to the stripping section 32 and is also provided with a production pipe 4 to form an external circulation, the production pipe 4 is installed with a reboiler 7, which can further desorb CO2, the reboiler of the present invention can use a conventional reboiler, the present invention has no special requirements for this, and it will not be repeated.

[0076] In order to return the lean liquid regenerated from the rich liquid to the absorption tower 2 to absorb CO2, the stripping section 32 in the present invention is connected to the solvent feed pipe 21 through a pipeline, and in order to further save energy, a lean-rich liquid heat exchanger can be arranged on the pipeline to use the heat of the lean liquid drawn out of the desorption tower to preheat the rich liquid entering the desorption tower from the absorption tower, and the lean liquid after heat exchange is cooled and enters the absorption tower.

[0077] Furthermore, in order to discharge the desorbed CO2 and part of the solution vapor, the desorption tower 3 is connected to a CO2 product gas discharge pipe 33; there is no special requirement for the desorption tower in the present invention. For example, the CO2 product gas discharge pipe 33 can be connected to a water cooler, the water cooler is connected to an underground tank and has a product gas outlet, the underground tank is connected to the desorption tower 3, the water cooler is used to condense the CO2 from the desorption tower 3, the condensed CO2 is discharged from the product gas outlet, the separated condensed water enters the underground tank and returns to the desorption tower 3, which will not be repeated here.

[0078] In some embodiments of the present invention, in order to collect the flue gas heat of the hot flue gas in the flue gas feed pipe, such as Figure 1 As shown, the first heat exchange section includes a first heat exchanger 5 installed on the flue gas feed pipe 11; in order to collect the CO2 heat of the CO2 desorbed in the desorption unit, the third heat exchange section includes a third heat exchanger 6 installed on the CO2 product gas discharge pipe 33 between the water cooler and the desorption tower 3; in order to provide the collected flue gas heat and the top steam heat of the desorption tower 3 to the stripping section 32, the second heat exchange section includes a reboiler 7 installed on the production pipe 4.

[0079] In order to realize the above-mentioned heat collection and output utilization so as to save energy consumption and cost, in some embodiments of the present invention, the flue gas feed pipe 11 is connected to the shell side of the first heat exchanger 5, and the tube side of the first heat exchanger 5 forms a first circulation pipe for circulating heat exchange medium (the present invention has no special requirements for the heat exchange medium, and the conventional heat exchange medium that can meet the heat exchange function in the prior art can be used), and the first circulation pipe is connected to the separation tank 8 and the collection tank; the CO2 product gas discharge pipe 33 is connected to the shell side of the third heat exchanger 6, and the tube side of the third heat exchanger 6 forms a third circulation pipe for circulating heat exchange medium, and the third circulation pipe is connected to the separation tank 8 and the collection tank; the shell side of the reboiler 7 is connected to the separation tank 8 and the collection tank through the second circulation pipe, and the production pipe 4 forms the tube side of the reboiler 7.

[0080] In order to further save energy consumption and cost, in some embodiments of the present invention, a heat pump compressor 9 is arranged on the second circulation pipe, so that the flue gas heat of the hot flue gas and the heat of the discharge material of the desorption tower, including the CO2 heat discharged from the CO2 product gas discharge pipe (33) and the heat of part of the solution vapor and the heat of the top steam (including the CO2 heat and the heat of the solution vapor), enter the stripping section 32 after being heated and pressurized by the heat pump compressor 9. In the present invention, the heat pump compressor 9 is selected from one of a centrifugal compressor, a screw compressor or a reciprocating compressor. In the present invention, there is no special requirement for the type of working fluid of the heat pump compressor, including but not limited to fluorocarbon refrigerants (such as R245, R600a or R123), alcohol refrigerants, water or composite working fluids.

[0081] In the prior art, a large amount of cooling water is consumed for cooling the hot flue gas and the top product of the desorption tower (mainly including the desorbed CO2 and carrying steam), and there is a large waste of energy in the process. According to the disclosure of the present invention, the present invention aims to integrate the cooling and heating requirements in the current wet decarbonization process, and utilize the heat pump technology to use the heat of the flue gas and the steam from the top of the desorption tower as the heat source of the desorption tower, thereby saving steam and cooling water consumption and reducing the cost of CO2 production.

[0082] In the present invention, various parts can be added with various pipelines, control valves, pumps, separation tanks, collection tanks or instruments, etc., as well as conventional parts that may be needed in industry as needed, and the present invention has no special requirements for this.

[0083] The present invention will be described in detail below by way of examples, but the present invention is not limited thereto.

[0084] Example 1

[0085] use Figure 1 The wet flue gas decarbonization equipment shown in the figure processes about 40,000Nm 3 / h coal boiler to get hot flue gas after desulfurization and denitrification. The process includes the following:

[0086] The hot flue gas temperature is 150-180 degrees. After passing through the first heat exchanger 5, the recovered flue gas heat enters the low-pressure liquid methanol, and then passes through the water washing tower 1, contacts with the washing water, and is cooled and washed to 40 degrees. It is then sent to the absorption tower 2 by the fan, wherein CO2 is absorbed by the monoethanolamine aqueous solution (mass concentration 20%), and the tail gas is discharged into the atmosphere from the tail gas outlet at the top of the tower. The rich liquid after absorbing CO2 passes through the poor-rich liquid heat exchanger at the bottom of the tower, and is sent to the desorption tower 3 after recovering heat. The desorbed CO2 is cooled together with the water vapor through the third heat exchanger 6, and after recovering part of the heat to the low-pressure liquid methanol, the water is separated and removed, and the product gas with a CO2 purity of 99% is obtained and sent to the subsequent process for use.

[0087] The heat exchange medium, low-pressure liquid methanol, circulates among the first heat exchanger 5, the third heat exchanger 6, the reboiler 7 and the centrifugal compressor, wherein heat is recovered in the first heat exchanger 5 and the third heat exchanger 6, and after evaporating into a gas phase, it enters the centrifugal compressor, and the pressure and temperature will increase. It enters the reboiler 7 of the desorption tower 3 as a heat source. After the heat is output, the cooled and liquefied heat exchange medium enters the collection tank, and the liquid phase in the collection tank continues to circulate.

[0088] The energy consumption of Example 1 is shown in Table 1 below:

[0089] Table 1

[0090]

[0091] Comparative Example 1

[0092] The difference from the first embodiment is that no heat circulation unit is used, that is, the first heat exchanger 5, the third heat exchanger 6 and the heat pump compressor 9 are not provided, and the heat is not recovered for use in the reboiler 7. Figure 2 As shown, the energy consumption of comparative example 1 is as shown in Table 2:

[0093] Table 2

[0094]

[0095] By comparison, it can be seen that the improved process has lower comprehensive energy consumption per unit CO2 and production costs than the traditional process.

[0096] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A method for wet flue gas decarbonization, It is characterized in that The method includes the following: 1) Wash the hot flue gas with water to remove water-soluble impurities; 2) The washed flue gas is contacted with a solvent to obtain a solution that absorbs CO 2 of rich solution; 3) Stripping and desorbing the rich liquid to obtain CO 2 and lean solution; The heat of the hot flue gas before water washing in step 1) is collected and used for steam stripping and desorption in step 3).

2. The method according to claim 1, in, The method further comprises: collecting the heat of the discharged material in step 3) for use in the steam stripping desorption in step 3); and / or The hot flue gas comes from at least one of the tail gas of a coal boiler, the tail gas of a natural gas boiler or the tail gas of an oil boiler; the composition of the hot flue gas includes: N 2 , CO 2 , H 2 O, O 2 、SO 2 、NO x , dust and oil; The temperature of the hot flue gas is 80-250° C.; and / or In step 2), the flue gas temperature after water washing is ≤50°C.

3. The method according to claim 1 or 2, in, The water-soluble impurities in step 1) include SO 2 、NO x , at least one of dust and oil; and / or In step 2), the solvent comprises at least one of a monoethanolamine aqueous solution, a diethanolamine aqueous solution or a methyldiethanolamine aqueous solution; and / or The contact conditions in step 2) include: temperature range 40-50° C., normal pressure; and / or The conditions for stripping and desorption in step 3) include: temperature range 100-130° C., pressure range 0.1-0.2 MPa; and / or The lean liquid in step 3) is returned to step 2) to contact with the flue gas after water washing to absorb CO 2 .

4. A device for wet flue gas decarbonization, It is characterized in that The equipment for wet flue gas decarbonization comprises: A water washing unit connected to the flue gas feed pipe (11) and used for washing the hot flue gas with water to remove water-soluble impurities; The absorption unit is connected to the water washing unit and is used to contact the flue gas after water washing with the solvent so that the solvent absorbs the CO in the flue gas. 2 Forming a rich solution; A desorption unit is connected to the absorption unit and comprises a stripping section (32) for stripping and desorbing the rich liquid to obtain CO 2 and lean solution; A heat circulation unit is used for collecting the flue gas heat of the hot flue gas in the flue gas feeding pipe and providing the flue gas heat to the stripping section (32).

5. The device for wet flue gas decarbonization according to claim 4, in, The heat circulation unit comprises a first heat exchange part and a second heat exchange part which are connected to each other, wherein the first heat exchange part is used to collect the flue gas heat of the hot flue gas in the flue gas feeding pipe, and the second heat exchange part is used to provide the flue gas heat collected by the first heat exchange part to the stripping part (32); Preferably, the circulation unit further comprises a third heat exchange section, wherein the third heat exchange section is used to collect the heat of the discharge material in the desorption unit, and the third heat exchange section is connected to the second heat exchange section to provide the heat of the discharge material to the stripping section (32).

6. The device for wet flue gas decarbonization according to claim 4, in, The water washing unit comprises a water washing tower (1), and the water washing tower (1) is connected to the flue gas feed pipe (11) and the washing water feed pipe (12); Preferably, the flue gas feed pipe (11) is connected to the lower part of the water scrubber (1), and the discharge port of the washing water feed pipe (12) is connected to the upper part of the water scrubber (1), so that the washing water fed by the washing water feed pipe (12) is in countercurrent contact with the hot flue gas fed by the flue gas feed pipe (11); More preferably, the washing water feed pipe (12) is connected to the bottom of the water washing tower (1) to circulate the washing water falling to the bottom of the water washing tower (1) back to the upper part of the water washing tower (1).

7. The device for wet flue gas decarbonization according to claim 6, in, The absorption unit comprises an absorption tower (2), wherein the absorption tower (2) is connected to the water washing tower (1) and is connected to a solvent feed pipe (21), wherein the solvent feed pipe (21) is used to introduce a solvent into the absorption tower (2) and to allow the solvent to countercurrently contact with the flue gas after water washing to obtain a solvent having absorbed CO. 2 of rich solution; Preferably, The lower part of the absorption tower (2) is connected to the top of the water washing tower (1), and the solvent feed pipe (21) is connected to the upper part of the absorption tower (2); and / or The top of the absorption tower (2) is provided with an exhaust gas outlet, and the exhaust gas outlet is used to discharge the exhaust gas after the flue gas after water washing contacts with the solvent.

8. The device for wet flue gas decarbonization according to claim 7, in, The desorption unit comprises a desorption tower (3), wherein the desorption tower (3) comprises a desorption section (31) and a stripping section (32) which are connected to each other, wherein the desorption section (31) is connected to the absorption tower (2), and the stripping section (32) is used to provide steam to the desorption section (31) and to make the rich liquid from the absorption tower (2) contact with the steam in countercurrent to perform desorption to obtain the lean liquid and CO 2 ; Preferably, The desorption tower (3) is connected to a CO 2 The product gas discharge pipe (33) is used to discharge the desorbed CO 2 and part of the solution steam is discharged, and the heat of the discharged material includes CO 2 The CO discharged from the product gas discharge pipe (33) 2 heat and part of the heat of solution vapor; and / or The stripping section (32) is located at the lower part of the desorption tower (3), the desorption section (31) is located above the stripping section (32), the desorption section (31) and the stripping section (32) are connected through a production pipe (4), and a reboiler (7) is installed on the production pipe (4); and / or The stripping section (32) is connected to the solvent feed pipe (21) and is used to return the lean liquid to the absorption tower (2) for absorbing CO 2 .

9. The device for wet flue gas decarbonization according to claim 4, in, The first heat exchange part includes a first heat exchanger (5) installed on the flue gas feed pipe (11), the second heat exchange part includes a reboiler (7), and the third heat exchange part includes a CO2-free heat exchanger installed between the water cooler and the desorption tower (3). 2 A third heat exchanger (6) on the product gas discharge pipe (33); Preferably, The flue gas feed pipe (11) is connected to the shell side of the first heat exchanger (5), the tube side of the first heat exchanger (5) forms a first circulation pipe for circulating a heat exchange medium, and the first circulation pipe is connected to a separation tank (8); The CO 2 The product gas discharge pipe (33) is connected to the shell side of the third heat exchanger (6), and the tube side of the third heat exchanger (6) forms a third circulation pipe for circulating the heat exchange medium, and the separation tank (8) is connected to the third circulation pipe; The shell side of the reboiler (7) is connected to the separation tank (8) via a second circulation pipe, and the extraction pipe (4) forms the tube side of the reboiler (7).

10. The device for wet flue gas decarbonization according to claim 9, in, The second circulation pipe is provided with a heat pump compressor (9), and the heat pump compressor (9) is preferably selected from a centrifugal compressor, a screw compressor or a reciprocating compressor.

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