Semi-rich liquid carbon dioxide regeneration device and method based on regeneration gas waste heat recovery

Abstract

The present application relates to a kind of based on semi-rich liquid carbon dioxide regenerator and method of regeneration gas waste heat recovery, the semi-rich liquid carbon dioxide regenerator, including primary lean rich liquid heat exchanger, secondary lean rich liquid heat exchanger, semi-rich liquid regenerator, circulating pump and compressor;The primary lean rich liquid heat exchanger and secondary lean rich liquid heat exchanger are respectively connected with semi-rich liquid regenerator by pipeline, the primary lean rich liquid heat exchanger is connected with secondary lean rich liquid heat exchanger by pipeline, and the semi-rich liquid regenerator is connected with circulating pump and compressor respectively by pipeline.In the present application, the carbon dioxide regeneration gas generated in regenerator is lifted after being compressed by MVR compressor, enters regenerator to release heat, generates semi-rich liquid regeneration gas, recovers low-temperature waste heat, reduces the energy loss of carbon dioxide absorption method.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of waste heat recovery of regenerated gas, and relates to a semi-rich-liquid carbon dioxide regeneration device and method based on waste heat recovery of regenerated gas. BACKGROUND

[0002] In the post-combustion carbon dioxide capture process, heat energy is consumed to break the chemical bond between the solvent and the carbon dioxide (reaction heat), to increase the temperature of the solvent to the reboiler temperature (sensible heat), to produce water vapor and to heat the reflux (non-productive heat). Only by using more effective solvents and catalysts can the reaction heat be reduced. The sensible heat and the non-productive heat are avoidable parts of the regeneration energy, which can be reduced by improving the method configuration. Method improvement is a simple and effective method to reduce the heat energy demand, because it can be realized by making minimum modifications to any existing facility. There are three optimization schemes for method flow optimization: (1) enhanced absorption, increasing the carbon dioxide load of the rich liquid near the bottom of the absorber to increase the solvent capacity and reduce the reboiler load; (2) heat integration, recovering waste heat by transferring heat between streams to reduce heat loss of the reboiler; (3) adding a heat pump to improve the heat quality at the cost of additional mechanical work.

[0003] At present, the rich-liquid split flow and split flow arrangement based on post-combustion carbon dioxide capture method schemes have been successfully researched at home and abroad. These method schemes can be used to reduce heat loss and final reboiler load, to increase carbon dioxide load and to enhance absorption capacity, but cannot maximize the reduction of heat loss and final reboiler load, and the carbon dioxide load and absorption capacity cannot be maximized. Moreover, the low-temperature waste heat generated in the capture process cannot be effectively utilized, resulting in high overdraft cost, large energy consumption and high operating cost. SUMMARY

[0004] Therefore, the main purpose of the present application is to provide a semi-rich-liquid carbon dioxide regeneration device and method based on waste heat recovery of regenerated gas, which can effectively recover part of the heat of the regenerated gas at the top of the tower, i.e., can maximize the reduction of heat consumed in the subsequent rich-liquid regeneration; at the same time, the consumption of circulating cooling water can also be reduced, so as to achieve the effect of overall energy saving. Compared with other carbon dioxide capture methods, this method scheme can save investment, reduce energy consumption and operating cost, and realize high-efficiency capture of carbon dioxide.

[0005] In order to achieve the above-mentioned purpose, the application provides a semi-rich liquid carbon dioxide regenerator based on regenerative gas waste heat recovery, which comprises a first lean-rich liquid heat exchanger, a second lean-rich liquid heat exchanger, a semi-rich liquid regenerator, a circulating pump and a compressor; the first lean-rich liquid heat exchanger and the second lean-rich liquid heat exchanger are respectively connected with the semi-rich liquid regenerator through pipelines, the first lean-rich liquid heat exchanger is connected with the second lean-rich liquid heat exchanger through a pipeline, and the semi-rich liquid regenerator is respectively connected with the circulating pump and the compressor through pipelines.

[0006] Further, the first lean-rich liquid heat exchanger is a plate heat exchanger or a shell-and-tube heat exchanger, preferably a plate heat exchanger, which has a high heat transfer coefficient, a large heat exchange area, a small land area, a low price, a low fouling coefficient and a small terminal temperature difference.

[0007] Further, the second lean-rich liquid heat exchanger is a plate heat exchanger or a shell-and-tube heat exchanger, preferably a plate heat exchanger, which has a high heat transfer coefficient, a large heat exchange area, a small land area, a low price, a low fouling coefficient and a small terminal temperature difference.

[0008] Further, the semi-rich liquid regenerator is a plate heat exchanger or a shell-and-tube heat exchanger, preferably a plate heat exchanger, which has a high heat transfer coefficient, a large heat exchange area, a small land area, a low price, a low fouling coefficient and a small terminal temperature difference.

[0009] Further, the semi-rich liquid regenerator is an MVR semi-rich liquid regenerator, which includes but is not limited to a horizontal-tube falling-film evaporator, a vertical-tube falling-film evaporator or a rising-film evaporator.

[0010] Further, the compressor is an MVR compressor, which includes but is not limited to a centrifugal compressor, a screw compressor or a Roots compressor.

[0011] Further, the first lean-rich liquid heat exchanger is further connected with a rich liquid storage tank.

[0012] In order to achieve the above-mentioned purpose, the application provides a semi-rich liquid carbon dioxide regeneration method based on regenerative gas waste heat recovery, which comprises the following steps: firstly, rich liquid with a temperature of 51-56℃ and lean liquid with a temperature of 105-110℃ are arranged in a heat exchange mode through two-stage series counter-flow inter-wall heat transfer, then primary CO2 regeneration is carried out through a heat exchange mode of inter-stage rich liquid, and finally, the remaining rich liquid is returned to the second lean-rich liquid heat exchanger for heating to carry out deep distillation regeneration.

[0013] Further, wherein the semi-rich liquid carbon dioxide regeneration method based on waste heat recovery of regeneration gas comprises the following steps: the rich liquid with a temperature of 51-56 ℃ and a pressure of 4-5 bar enters a first lean-rich liquid heat exchanger and exchanges heat with the lean liquid with a temperature of 105-110 ℃ and a pressure of 4-5 bar flowing out of a second lean-rich liquid heat exchanger, and the rich liquid after the first lean-rich liquid heat exchanger is heated to 80 ℃; then 50wt%-100wt% of the rich liquid at 80 ℃ enters a semi-rich liquid regenerator to perform primary carbon dioxide regeneration; the rich liquid at 80 ℃ is heated to 85 ℃ in the semi-rich liquid regenerator and generates semi-rich liquid regeneration gas (1.0-1.2.bar, 90-100 ℃, vaporization rate about 3wt%), and the remaining 47wt%-97wt% of the semi-rich liquid is pumped back to the rich liquid pipeline by a circulating pump, mixed with the original rich liquid not participating in the primary regeneration, and enters the second lean-rich liquid heat exchanger to exchange heat with the lean liquid at 105-110 ℃, and the rich liquid after the second lean-rich liquid heat exchanger is heated to 100-105 ℃ and performs subsequent deep CO2 regeneration.

[0014] Further, wherein the semi-rich liquid regeneration gas is mixed with the regeneration gas at the top of the desorption tower to generate pressurized regeneration gas with a pressure of 1.8-2.2 bar and a temperature of 120-160 ℃, and then enters the semi-rich liquid regenerator to desorb the rich liquid at 80 ℃, and finally forms regeneration gas with a pressure of 1.0-1.8 bar and a temperature of 90-100 ℃ flowing out of the semi-rich liquid regenerator; wherein the grade of water vapor is improved, and then enters the semi-rich liquid regenerator as a heat source to heat the rich liquid.

[0015] Further, wherein the semi-rich liquid regeneration gas has a pressure of 1.0-1.2.bar, a temperature of 90-100 ℃, and a vaporization rate of 3wt%.

[0016] Further, wherein the rich liquid is a composite amine solution with a mass fraction of 20-30%, and the concentration of carbon dioxide in the composite amine solution is 3-4mol%.

[0017] Further, wherein the lean liquid in the desorption tower is a composite amine solution with a mass fraction of 20-30%, and the concentration of carbon dioxide in the composite amine solution is 1-2mol%.

[0018] The composite amine solution absorbs carbon dioxide to become rich liquid, and releases carbon dioxide in the desorption tower to become lean liquid.

[0019] Further, wherein the circulating liquid amount of the remaining liquid is 5-100 times the vaporization amount.

[0020] Further, wherein the volume ratio of the semi-rich liquid regeneration gas to the regeneration gas at the top of the desorption tower is 1:(3-4), preferably 1:3, the pre-regeneration ratio is high, the amount of waste heat recovered is large, the heat load of the subsequent desorption tower regeneration is correspondingly reduced, and the public steam resource required for regeneration is saved.

[0021] Further, the composition of the semi-rich liquid regeneration gas is 30-45% carbon dioxide and 55-70% water vapor by volume fraction, preferably 40% carbon dioxide and 60% water vapor, to ensure better heat supply for the compressor.

[0022] Further, the composition of the semi-rich liquid regeneration gas is 30-45% carbon dioxide and 55-70% water vapor by volume fraction, preferably 40% carbon dioxide and 60% water vapor, to ensure better heat supply for the compressor.

[0023] Further, the composition of the semi-rich liquid regeneration gas is 30-45% carbon dioxide and 55-70% water vapor by volume fraction, preferably 40% carbon dioxide and 60% water vapor, to ensure better heat supply for the compressor.

[0024] Compared with the prior art, the present application has the following beneficial effects:

[0025] The semi-rich liquid carbon dioxide regeneration method based on regeneration gas waste heat recovery of the present application is based on the chemical absorption capture method of post-combustion carbon dioxide capture. Compared with other carbon dioxide capture methods, the lean-rich liquid heat exchanger in the present application is divided into two stages, the first stage heat exchanger heats the rich liquid to 80-85 DEG C, a part of the rich liquid enters the MVR semi-rich liquid regenerator and is heated to regenerate carbon dioxide, and the remaining liquid is pumped back to the rich liquid pipeline by a circulating pump and mixed with another part of the original rich liquid to enter the second stage heat exchanger, thereby reducing the energy of the solvent regeneration and the load of the reboiler.

[0026] In the present application, the regeneration gas from outside the system and the carbon dioxide regeneration gas generated by the semi-rich liquid regenerator are compressed by the MVR compressor to improve the grade, then enter the regenerator to release heat, generate semi-rich liquid regeneration gas, recover low-temperature waste heat, and reduce the energy loss of the carbon dioxide absorption method.

[0027] The semi-rich liquid carbon dioxide regeneration method based on regeneration gas waste heat recovery of the present application can effectively recover part of the heat of the tower top regeneration gas, can reduce the consumption of circulating cooling water, thereby achieving the overall energy-saving effect of the carbon dioxide absorption method, and realizing high-efficiency capture of carbon dioxide.

[0028] The semi-rich liquid carbon dioxide regeneration method based on regeneration gas waste heat recovery of the present application can effectively recover part of the heat of the tower top regeneration gas, can reduce the consumption of circulating cooling water, thereby achieving the overall energy-saving effect of the carbon dioxide absorption method, and realizing high-efficiency capture of carbon dioxide. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1A structure schematic view of a semi-rich liquid carbon dioxide regenerator based on waste heat recovery of regenerated gas according to the embodiment 1 of the present application;

[0030] Figure 2 A structure schematic view of a semi-rich liquid carbon dioxide regenerator based on waste heat recovery of regenerated gas according to the embodiment 2 of the present application;

[0031] 1-semi-rich liquid regenerator; 2-circulating pump; 3-first-stage lean-rich liquid heat exchanger; 4-second-stage lean-rich liquid heat exchanger; 5-compressor. DETAILED DESCRIPTION

[0032] In order to further clarify the technical means and effects taken by the present application to achieve the predetermined purposes, the specific implementation, features and effects of the semi-rich liquid carbon dioxide regenerator and method based on waste heat recovery of regenerated gas according to the present application are described in detail as follows in combination with the preferred embodiments.

[0033] The following materials or reagents are commercially available unless otherwise specified.

[0034] Embodiment 1

[0035] As Figure 1The embodiment shown provides a semi-rich liquid carbon dioxide regeneration device based on regeneration gas waste heat recovery, which comprises a first lean-rich liquid heat exchanger 3, a second lean-rich liquid heat exchanger 4, a semi-rich liquid regenerator 1, a circulating pump 2 and a compressor 5. The first lean-rich liquid heat exchanger 3 and the second lean-rich liquid heat exchanger 4 are respectively connected with the semi-rich liquid regenerator 1 through pipelines, the first lean-rich liquid heat exchanger 3 is connected with the second lean-rich liquid heat exchanger 4 through a pipeline, and the semi-rich liquid regenerator 1 is respectively connected with the circulating pump 2 and the compressor 5 through pipelines. In the embodiment, the first lean-rich liquid heat exchanger 3 and the second lean-rich liquid heat exchanger 4 are both plate heat exchangers, the semi-rich liquid regenerator 1 is an MVR semi-rich liquid regenerator, and the compressor 5 is an MVR compressor. In addition, the first lean-rich liquid heat exchanger 3 is also connected with a rich liquid storage tank. Specifically, the rich liquid from the rich liquid storage tank is connected with the rich liquid inlet of the first lean-rich liquid heat exchanger 3 through a pipeline, the rich liquid outlet of the first lean-rich liquid heat exchanger 3 is divided into two paths, one rich liquid direct pipeline is connected with the rich liquid inlet of the second lean-rich liquid heat exchanger 4, and the other rich liquid bypass pipeline is connected with the liquid phase inlet at the top of the shell side of the semi-rich liquid regenerator 1. The gas phase outlet at the top of the shell side of the semi-rich liquid regenerator 1 is combined with the regeneration gas pipeline from the outside, and the liquid phase outlet at the bottom of the shell side of the semi-rich liquid regenerator 1 is connected with the inlet of the circulating pump 2. The outlet pipeline of the circulating pump 2 is divided into two paths, one direct pipeline is combined with the rich liquid bypass pipeline of the first lean-rich liquid heat exchanger 3 and then enters the top of the shell side, and the other bypass pipeline is combined with the rich liquid direct pipeline of the first lean-rich liquid heat exchanger 3. The lean liquid pipeline from the outside is connected with the lean liquid inlet of the second lean-rich liquid heat exchanger 4, the lean liquid outlet pipeline of the second lean-rich liquid heat exchanger 4 is connected with the lean liquid inlet of the first lean-rich liquid heat exchanger 3, the combined regeneration gas pipeline is connected with the inlet of the MVR compressor 5, and the outlet pipeline of the MVR compressor 5 is connected with the inlet of the tube side of the semi-rich liquid regenerator 1.

[0036] The semi-rich liquid regenerator adopts a horizontal tube outside falling film heat exchanger (the specific form of the semi-rich liquid regenerator), the rich liquid outlet pipeline of the first lean-rich liquid heat exchanger 3 is connected with the liquid phase inlet at the top of the shell side of the semi-rich liquid regenerator 1 through a pipeline, the gas phase outlet at the top of the shell side of the semi-rich liquid regenerator 1 is connected with the regeneration gas pipeline from the outside through a pipeline, the liquid phase outlet at the bottom of the shell side of the semi-rich liquid regenerator 1 is connected with the inlet of the circulating pump 2, and the outlet of the circulating pump 2 is respectively connected with the liquid phase inlet at the top of the shell side of the semi-rich liquid regenerator 1 and the rich liquid inlet of the second lean-rich liquid heat exchanger 4. The outlet pipeline of the MVR compressor 5 is connected with the inlet of the tube side of the semi-rich liquid regenerator 1. The specific process is that the pressurized regeneration gas passes through the tube side, releases heat and is partially condensed (the water vapor is partially condensed), the semi-rich liquid passing through the shell side is heated and partially gasified, the gasified regeneration gas flows out from the top of the shell side, and the remaining rich liquid is discharged from the bottom of the shell side.

[0037] The specific steps of the semi-rich liquid carbon dioxide regeneration method based on regeneration gas waste heat recovery are as follows:

[0038] The rich solution (20wt% of complex amine solution, 3mol% of carbon dioxide in the complex amine solution) at 56°C from the bottom of the absorption tower enters the primary lean-rich solution heat exchanger 3 to exchange heat with the lean solution (20wt% of complex amine solution, 1.5mol% of carbon dioxide in the complex amine solution) from the secondary lean-rich solution heat exchanger 4, and the rich solution is preliminarily heated to 80°C in the primary lean-rich solution heat exchanger 3. The outlet is divided into two paths, one of which is the rich solution (50wt%) that enters the semi-rich solution regenerator 1 for primary CO2 regeneration. The rich solution at 80°C is heated to 85°C, and the semi-rich solution regeneration gas (1.2.bar, 95°C, vaporization rate of about 3wt%, 40%(v / v) water vapor + 60%(v / v) carbon dioxide) at 90°C is generated. The semi-rich solution regeneration gas (40% of carbon dioxide and 60% of water vapor) generated from the top gas phase outlet of the semi-rich solution regenerator 1 is combined with the regeneration gas (i.e., the regeneration gas generated by deep distillation of CO2 from the rich solution, 40% of carbon dioxide and 60% of water vapor) from the top of the desorption tower (the volume ratio of semi-rich solution regeneration gas to regeneration gas from the top of the desorption tower is 1:3), and then enters the MVR compressor 5. After being increased in temperature and pressure to a pressure of 2.1bar and a temperature of 145°C, the semi-rich solution regeneration gas is used as a heat source to enter the tube side of the semi-rich solution regenerator 1. After being heated by the double tube side heat exchange in the semi-rich solution regenerator 1, the semi-rich solution is fully released of heat (latent heat of water vapor). The remaining semi-rich solution after being heated by the pressurized regeneration gas (40% of carbon dioxide and 60% of water vapor) from the outlet of the MVR compressor 5 and releasing part of the regeneration gas (equivalent to 53wt% of the CO2 load of the semi-rich solution) is pressurized to about 300kPa by the circulating pump 2 (to overcome the pressure head of flow resistance), and then mixed with the rich solution (50wt%) from the primary lean-rich solution heat exchanger 3 to continue circulation. The remaining 47wt% of the semi-rich solution (its circulating liquid amount is 50 times the vaporization amount) is combined with the unregenerated rich solution (50wt%) from the primary lean-rich solution heat exchanger 3, and then enters the secondary lean-rich solution heat exchanger 4 to exchange heat with the lean solution at 105°C. After being heated to 100°C, deep distillation regeneration is performed.

[0039] Example 2

[0040] As Figure 2The embodiment shown provides a semi-rich liquid carbon dioxide regeneration device based on regeneration gas waste heat recovery, which comprises a first lean-rich liquid heat exchanger 3, a second lean-rich liquid heat exchanger 4, a semi-rich liquid regenerator 1, a circulating pump 2 and a compressor 5. The first lean-rich liquid heat exchanger 3 and the second lean-rich liquid heat exchanger 4 are respectively connected with the semi-rich liquid regenerator 1 through pipelines, the first lean-rich liquid heat exchanger 3 is connected with the second lean-rich liquid heat exchanger 4 through a pipeline, and the semi-rich liquid regenerator 1 is respectively connected with the circulating pump 2 and the compressor 5 through pipelines. In the embodiment, the first lean-rich liquid heat exchanger 3 and the second lean-rich liquid heat exchanger 4 are both plate heat exchangers, the semi-rich liquid regenerator 1 is an MVR semi-rich liquid regenerator, and the compressor 5 is an MVR compressor. In addition, the first lean-rich liquid heat exchanger 3 is also connected with a rich liquid storage tank. Specifically, the rich liquid from the rich liquid storage tank is connected with the rich liquid inlet of the first lean-rich liquid heat exchanger 3 through a pipeline, the rich liquid outlet of the first lean-rich liquid heat exchanger 3 is divided into two paths, one rich liquid direct pipeline is connected with the rich liquid inlet of the second lean-rich liquid heat exchanger 4, and the other rich liquid bypass pipeline is connected with the liquid phase inlet at the top of the tube side of the semi-rich liquid regenerator 1. The gas phase outlet at the bottom of the tube side of the semi-rich liquid regenerator 1 is combined with the regeneration gas pipeline from the outside, the liquid phase outlet at the bottom of the tube side of the semi-rich liquid regenerator 1 is connected with the inlet of the circulating pump 2, and the outlet pipeline of the circulating pump 2 is divided into two paths, one direct pipeline is combined with the rich liquid bypass pipeline from the first lean-rich liquid heat exchanger 3, and the other bypass pipeline is combined with the rich liquid direct pipeline from the first lean-rich liquid heat exchanger 3. The lean liquid pipeline from the outside is connected with the lean liquid inlet of the second lean-rich liquid heat exchanger 4, the lean liquid outlet pipeline of the second lean-rich liquid heat exchanger 4 is connected with the lean liquid inlet of the first lean-rich liquid heat exchanger 3, the combined regeneration gas pipeline is connected with the inlet of the MVR compressor 5, and the outlet pipeline of the MVR compressor 5 is connected with the shell side inlet of the semi-rich liquid regenerator 1.

[0041] The semi-rich liquid regenerator adopts a vertical tube in-film heat exchanger (a specific form of the semi-rich liquid regenerator), the rich liquid outlet pipeline of the first lean-rich liquid heat exchanger 3 is connected with the liquid phase inlet at the top of the tube side of the semi-rich liquid regenerator 1 through a pipeline, the gas phase outlet at the top of the tube side of the semi-rich liquid regenerator 1 is connected with the regeneration gas pipeline from the outside through a pipeline, the liquid phase outlet at the bottom of the tube side of the semi-rich liquid regenerator 1 is connected with the inlet of the circulating pump 2, and the outlet of the circulating pump 2 is respectively connected with the liquid phase inlet at the top of the tube side of the semi-rich liquid regenerator 1 and the rich liquid inlet of the second lean-rich liquid heat exchanger 4. The outlet pipeline of the MVR compressor 5 is connected with the shell side inlet of the semi-rich liquid regenerator 1. The specific process is that the pressurized regeneration gas passes through the tube side, releases heat and is partially condensed (the water vapor is partially condensed), the semi-rich liquid passes through the shell side and is partially gasified by heat, the gasified regeneration gas flows out from the top of the shell side, and the remaining condensed liquid is discharged from the bottom of the shell side.

[0042] The specific steps of the semi-rich liquid carbon dioxide regeneration method based on regeneration gas waste heat recovery are as follows:

[0043] The 56℃ rich liquid (20wt% complex amine solution, 3mol% CO2 in the complex amine solution) from the bottom of the absorption tower enters the primary lean-rich liquid heat exchanger 3 to exchange heat with the lean liquid (20wt% complex amine solution, 1.5mol% CO2 in the complex amine solution) from the secondary lean-rich liquid heat exchanger 4, and the rich liquid is preliminarily heated to 80℃ in the primary lean-rich liquid heat exchanger 3. The outlet is divided into two paths, one of which is the rich liquid (50wt%) that enters the tube side of the semi-rich liquid regenerator 1, and a liquid film is formed on the inner and outer surfaces of the heat exchange tube and flows downward. The 80℃ rich liquid is heated to 85℃, and further generates 90℃ semi-rich liquid regeneration gas (1.2.bar, 95℃, vaporization rate about 3wt%, 40%(v / v) water vapor + 60%(v / v) carbon dioxide). The generated semi-rich liquid regeneration gas (40% carbon dioxide and 60% water vapor) is combined with the regeneration gas (i.e. the regeneration gas produced by deep distillation of CO2 from the rich liquid, 40% carbon dioxide and 60% water vapor) from the top of the desorption tower (the volume ratio of semi-rich liquid regeneration gas to regeneration gas from the top of the desorption tower is 1:3) and enters the MVR compressor 5. After increasing the temperature and pressure to improve the grade (pressure 2.1bar, temperature 145℃), it enters the shell side of the semi-rich liquid regenerator 1 as a heat source, and releases heat (latent heat of water vapor) through the tube-outer flow heat exchange inside the semi-rich liquid regenerator 1. The remaining semi-rich liquid after the tube-internal liquid film is heated by the pressurized regeneration gas (40% carbon dioxide and 60% water vapor) from the outlet of the MVR compressor 5 and releases part of the regeneration gas (equivalent to 53wt% of the semi-rich liquid CO2 load) is raised to about 300kPa by the circulating pump 2, and then mixed with the rich liquid (50wt%) from the primary lean-rich liquid heat exchanger 3 and continues to circulate. The remaining 47% of the semi-rich liquid (its circulating liquid amount is 50 times the vaporization amount) is combined with the unregenerated rich liquid (50wt%) from the primary lean-rich liquid heat exchanger 3 and enters the secondary lean-rich liquid heat exchanger 4 to exchange heat with the 105℃ lean liquid, and is heated to 100℃ for deep distillation regeneration.

[0044] The above is only a preferred embodiment of the present application, and does not limit the present application in any form. Any simple modification, equivalent change and modification of the above embodiment according to the technical essence of the present application still belongs to the scope of the technical solution of the present application.

Claims

1. A semi-rich liquid carbon dioxide regenerator based on waste heat recovery of regenerative gas, characterized in that, The application relates to a heat exchange device for a CO2 capture system, which comprises a primary lean-rich liquid heat exchanger, a secondary lean-rich liquid heat exchanger, a semi-rich liquid regenerator, a circulating pump and a compressor; the primary lean-rich liquid heat exchanger and the secondary lean-rich liquid heat exchanger are respectively connected with the semi-rich liquid regenerator through pipelines; the primary lean-rich liquid heat exchanger is connected with the secondary lean-rich liquid heat exchanger through a pipeline; the semi-rich liquid regenerator is respectively connected with the circulating pump and the compressor through pipelines. The primary lean-rich liquid heat exchanger heats the rich liquid to 80-85 DEG C; a part of the rich liquid enters the MVR semi-rich liquid regenerator to be heated and then is subjected to carbon dioxide regeneration; the remaining liquid is pumped back to the rich liquid pipeline by the circulating pump, is mixed with another part of the original rich liquid, and then enters the secondary lean-rich liquid heat exchanger to be heated.

2. The semi-rich liquid carbon dioxide regenerating apparatus according to claim 1, wherein The primary lean-rich liquid heat exchanger is a plate heat exchanger or a shell-and-tube heat exchanger; the secondary lean-rich liquid heat exchanger is a plate heat exchanger or a shell-and-tube heat exchanger; the semi-rich liquid regenerator is a plate heat exchanger or a shell-and-tube heat exchanger; the semi-rich liquid regenerator is an MVR semi-rich liquid regenerator; and the compressor is an MVR compressor.

3. The semi-rich liquid carbon dioxide regenerator as set forth in claim 1, wherein, The primary lean-rich liquid heat exchanger is further connected with a rich liquid storage tank.

4. A semi-rich liquid carbon dioxide regeneration process based on waste heat recovery of regeneration gas using the apparatus of any one of claims 1 to 3, characterized in that, The application further relates to a CO2 capture system, which comprises the heat exchange device.

5. The semi-rich liquid carbon dioxide regeneration process of claim 4 wherein, The application further relates to a CO2 capture system, which comprises the heat exchange device. The 51-56 DEG C rich liquid flowing out of the bottom of the absorption tower and the 105-110 DEG C lean liquid flowing out of the secondary lean-rich liquid heat exchanger are subjected to heat exchange in the primary lean-rich liquid heat exchanger; the rich liquid is heated to 80 DEG C in the primary lean-rich liquid heat exchanger; then 50wt%-100wt% of the 80 DEG C rich liquid enters the semi-rich liquid regenerator to be subjected to primary carbon dioxide regeneration; the 80-85 DEG C rich liquid is heated to 85 DEG C in the semi-rich liquid regenerator and generates semi-rich liquid regeneration gas; the remaining 47wt%-97wt% of the semi-rich liquid is pumped back to the rich liquid pipeline by the circulating pump, is mixed with the original rich liquid which does not participate in the primary regeneration, and then enters the secondary lean-rich liquid heat exchanger to be subjected to heat exchange with the 105-110 DEG C lean liquid; the rich liquid is heated to 100-105 DEG C in the secondary lean-rich liquid heat exchanger and is subjected to subsequent deep CO2 regeneration.

6. The semi-rich liquid carbon dioxide regeneration process of claim 5 wherein, The semi-rich liquid regeneration gas and the regeneration gas at the top of the desorption tower are mixed and then enter the compressor to be compressed, thereby generating 1.8-2.2 bar, 120-160 DEG C pressurized regeneration gas; then the pressurized regeneration gas enters the semi-rich liquid regenerator to desorb the 80 DEG C rich liquid; finally, 1.0-1.8 bar, 90-100 DEG C regeneration gas flows out of the semi-rich liquid regenerator.

7. The semi-rich liquid carbon dioxide regeneration process of claim 5 wherein, The semi-rich liquid regeneration gas has a pressure of 1.0-1.2 bar, a temperature of 90-100 DEG C and a vaporization rate of 3wt%.

8. The semi-rich liquid carbon dioxide regeneration process of claim 5 wherein, The rich liquid is a 20% mass fraction composite amine solution, wherein the concentration of carbon dioxide is 3-4mol%; the lean liquid is a 20% mass fraction composite amine solution, wherein the concentration of carbon dioxide is 1-2mol%.

9. The semi-rich liquid carbon dioxide regeneration process of claim 5 wherein, The circulating liquid amount of the remaining liquid is 5-100 times of the vaporization amount; the volume ratio of the semi-rich liquid regeneration gas to the regeneration gas at the top of the desorption tower is 1: (3-4).

10. The semi-rich liquid carbon dioxide regeneration process of claim 6 wherein, The semi-rich liquid regeneration gas is composed of 30-45% carbon dioxide and 55-70% water vapor by volume fraction; the regeneration gas at the top of the desorption tower is composed of 30-45% carbon dioxide and 55-70% water vapor; and the pressurized regeneration gas is composed of 35-45% carbon dioxide and 55-65% water vapor.

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