TWI790863B - Capture equipment with low energy consumption - Google Patents

Abstract

This invention relates to CO ₂capture equipment with low energy consumption and has a absorption equipment, a stripping equipment, a heat exchanger assembly and a heat pump. The heat pump has a heating end and a cooling end. The absorption equipment has an absorption tower and the stripping equipment has a stripping tower. The heat pump is located between the absorption equipment and the heat exchanger assembly, and the heat exchanger assembly is located between the heat pump and the stripping equipment. The heat exchanger assembly communicates with the absorption equipment and the stripping equipment. The present invention can effectively cool down a lean solvent from the stripping equipment by the cooling end of the heat pump. At the same time, a rich solvent from absorption equipment is effectively heated by the heating end of the heat pump. The overall energy consumption of the present invention is decreased effectively and the efficiency and economic benefit thereof is increased.

Description

Carbon dioxide capture device with low energy consumption

The invention relates to a carbon dioxide capture device adopting a chemical absorption method, in particular to a carbon dioxide capture device adopting a chemical absorption method with reduced energy consumption.

Since the industrial revolution, human beings have used fossil fuels and developed various petrochemical products in large quantities. Although it has made life much more convenient, it will increase the concentration of naturally occurring greenhouse gases such as methane (CH ₄ ) and carbon dioxide (CO ₂ ) in the atmosphere. Among them, carbon dioxide is currently the most important gas that causes the greenhouse effect, and its concentration has been rising continuously in the past century. If this problem is not solved, the excessive concentration of carbon dioxide in the atmosphere in the future will cause irreversible consequences.

With the rise of people's awareness of environmental protection, countries have begun to pay attention to carbon dioxide emissions, and have invested a lot of research on carbon dioxide emission reduction and recycling storage or reuse, trying to find effective ways to reduce CO ₂ .

Carbon capture and storage (CCS) refers to the technical process of collecting carbon dioxide from large-scale carbon dioxide emission sources, such as thermal power plants or incinerators, transporting it to storage locations and isolating it from the atmosphere for a long time. Capturing technologies can be broadly divided into solid-state adsorption and chemical absorption, among which chemical absorption is widely used; chemical absorption mainly utilizes the high The absorbent with selectivity makes the absorbent selectively absorb carbon dioxide. Because carbon dioxide is weakly acidic, alkaline solvents are generally used to absorb carbon dioxide, such as ammonia water, sodium hydroxide, alcohol amine, etc., but this method is prone to consumption during regeneration. The problem of high heat energy; as shown in Figure 6, it is one of the existing carbon dioxide capture devices 4 of the chemical absorption method, the carbon dioxide capture device 4 includes an absorption device 40, a heat exchanger 41, a stripping device 42 and A poor solvent cooler 43, wherein the absorber 40 comprises an absorption tower 401 and a flue gas cooler 402, and the stripper 42 comprises a stripper 421 and a reboiler 422; the stripper 42 is arranged on After the absorption unit 40 , the heat exchanger 41 is arranged between the absorption unit 40 and the stripping unit 42 , and the lean solvent cooler 43 is arranged between the heat exchanger 41 and the absorption unit 40 .

The carbon dioxide capture process of this carbon dioxide capture device 4 is: when a flue gas is transported and before entering the absorption tower 401, it will be cooled to an appropriate operating temperature by a flue gas cooler 402, and the cooled flue gas will be passed through the The bottom of the absorption tower 401 enters the absorption tower 401 and contacts with the poor solvent entering from the top of the absorption tower 401 to absorb most of the carbon dioxide in the flue gas and form a clean flue gas, and then clean the flue gas The gas is then discharged from the top of the absorption tower 401; at this time, the absorbent after absorbing carbon dioxide becomes a rich solvent containing carbon dioxide, and is transported into the heat exchanger 41 as the bottom product of the absorption tower 401.

The above-mentioned rich solvent performs heat exchange with the lean solvent produced by a stripping tower 421 of the stripping device 42 in the heat exchanger 41, wherein because the operating temperature of the absorption tower 401 is different from that of the stripping tower 421, the lean solvent is richer The solvent is hot, so the rich solvent can be heated through a heat exchanger, and the heated rich solvent enters the stripping tower 421 from the top of a stripping tower 421 of the stripping device 42, and is mixed with the vapor of the stripping tower 421 Carry out carbon dioxide stripping operation, to strip off carbon dioxide, this carbon dioxide can be discharged from the tower top of this stripping tower 421 and be further compressed and sealed up; The bottom product, a part of the poor solvent is refluxed to a reboiler 422 to reboil into vapor and strip the rich solvent, and the remaining part is transported to the heat exchanger 41 under pressure, and exchanges heat with the rich solvent as described above, most Afterwards, the lean solvent is cooled to a specific operating temperature by the lean solvent cooler 43 to serve as the lean solvent entering from the top of the absorption tower 401; therefore, in the carbon dioxide capture device 4, the lean solvent can be circulated use.

From Figure 6 and the above content, it can be seen that the current carbon dioxide capture device using the chemical absorption method only uses the heat exchanger to achieve the heat balance between the poor and rich solvents, and the absorbent used in the carbon dioxide capture device must still pass through before entering the absorption tower. The lean solvent cooler cools down to a certain low operating temperature, so that the lean solvent cooler must greatly increase energy consumption to cool the absorbent; in addition, if the temperature of the rich solvent entering from the top of the stripper is low, then The temperature of the lean solvent at the bottom of the tower decreases accordingly, and after the lower temperature lean solvent is refluxed to the reboiler, the reboiler must increase energy consumption to raise the temperature to a specific high operating temperature. Therefore, the energy consumption of the aforementioned lean solvent cooler and reboiler increases, that is, as shown in Figure 7, it takes more than 3.7 billion joules of energy consumption per ton of carbon dioxide to be captured, which will greatly increase the efficiency and economic benefits of the carbon dioxide capture device. Therefore, it is necessary to improve the existing carbon dioxide capture device for the heat transfer efficiency and energy consumption of the poor-rich solvent of the capture device.

In view of the low heat transfer efficiency and excessive energy consumption of the aforementioned carbon dioxide capture device, the main purpose of the present invention is to propose a carbon dioxide capture device that can improve heat transfer efficiency between poor and rich solvents and reduce energy consumption .

The main technical means used to achieve the above purpose is to make the low-energy carbon dioxide capture device include: an absorption device, which includes an absorption tower and a cooler; wherein a top of the absorption tower is connected to the cooling device, and a tower bottom of the absorption tower generates a rich solvent; A stripping device comprising a stripping tower and a reboiler, wherein the reboiler is arranged at a bottom of the stripping tower, and the bottom of the stripping tower generates a lean solvent; a heat exchanger The group is communicated with a tower top and the bottom of the absorption tower with a first flow channel and a second flow channel respectively, and is connected with a tower of the stripping tower with a third flow channel and a fourth flow channel respectively. The top of the tower is connected to the bottom of the tower; wherein the second flow channel and the third flow channel are used to transport the rich solvent, and the first flow channel and the fourth flow channel are used to transport the poor solvent; and a heat pump is It is arranged between the absorption device and the heat exchanger group, and includes: a hot end, which is used for the passage of the second channel to heat the rich solvent at the bottom of the absorption tower; and a cold end, which is used for The first flow channel passes to cool the lean solvent in the bottom of the stripper.

From the above description, it can be known that the low-energy carbon dioxide capture device of the present invention mainly uses a heat pump, which can transfer heat energy from a high-temperature heat source to a low-temperature heat source more efficiently by using the heat pump. The high-temperature lean solvent cools down, so that when the lean solvent enters the tower top of the absorption tower through the cooler, the cooler can make the lean solvent reach a low operating temperature with lower energy consumption; The temperature of the rich solvent is preheated by the hot end of the heat pump, which not only makes it easier for the rich solvent to remove carbon dioxide in the stripper, but also allows the reboiler to reboil the rich solvent into a high-temperature vapor with lower energy consumption; thus, The energy consumption of the refrigeration and heating devices in the carbon dioxide capture device of the present invention is reduced, so that the overall energy consumption is greatly reduced, and the efficiency and economic benefits of carbon dioxide capture are effectively improved.

1: Carbon dioxide capture device

10: Absorption device

101: Smoke flow channel

102a: the second runner

102b: the third runner

103a: the first runner

103b: the fourth runner

11: Absorption tower

110: tower top

111: tower bottom

12: storage tank

13: Cooler

2: Carbon dioxide capture device

20: Heat pump

201: condenser

202: evaporator

203: Compressor

204: throttle valve

21: Heat exchanger group

211: heat exchanger

22: Solar collector

3: Carbon dioxide capture device

30: Stripper

31: Stripper

310: tower top

311: tower bottom

32: Reboiler

4: Carbon dioxide capture device

40: Absorber

401: Absorption tower

402: Flue gas cooler

41: Heat exchanger

42: Stripper

421: stripper

422: Reboiler

43: Lean solvent cooler

Figure 1: A schematic diagram of the structure of the first embodiment of the low-energy carbon dioxide capture device of the present invention.

Fig. 2: A schematic diagram of the structure of the second embodiment of the low energy consumption carbon dioxide capture device of the present invention.

Fig. 3: A schematic diagram of the structure of the third embodiment of the low-energy-consumption carbon dioxide capture device of the present invention.

Fig. 4: A statistical chart of energy consumption of the first embodiment of the low-energy-consuming carbon dioxide capture device of the present invention.

Fig. 5: A statistical diagram of energy consumption of the second embodiment of the low-energy-consuming carbon dioxide capture device of the present invention.

Figure 6: A schematic diagram of an existing carbon dioxide capture device.

Figure 7: A statistical diagram of energy consumption of an existing carbon dioxide capture device.

The present invention mainly proposes a carbon dioxide capture device with high heat transfer efficiency and low energy consumption. The technical content of the present invention will be described in detail below with multiple embodiments and diagrams.

Please refer to Fig. 1 at first, it is the first embodiment of the low energy consumption carbon dioxide capture device of the present invention, this carbon dioxide capture device 1 comprises an absorption device 10, a stripping device 30, a heat exchanger group 21 and a heat pump 20, wherein the stripping unit 30 is arranged after the absorption unit 10, the heat pump 20 is arranged between the absorption unit 10 and the heat exchanger group 21, and the heat exchanger group 21 is arranged between the heat pump 20 and the Between the stripping unit 30.

The above-mentioned absorption device 10 comprises an absorption tower 11 and a cooler 13, and may further comprise a storage tank 12; wherein the storage tank 12 is arranged before the cooler 13, and the cooler 13 is arranged at the storage tank 12 and between the absorption tower 11, and connect a tower top 110, the cooler 13 and the storage tank 12 of the absorption tower 11 with a first flow channel 103a, in addition, a tower bottom 111 of the absorption tower 11 communicates with a smoke The gas flow path 101, and the bottom 111 of the absorption tower 11 generates a rich solvent.

Above-mentioned stripping device 30 comprises a stripping tower 31 and a reboiler 32, and wherein this reboiler 32 is arranged on a tower bottom 311 of this stripping tower 31, to provide a vapor to this stripping tower 31 and carry out stripping ;Should A tower top 310 of the stripper 31 receives the rich solvent from the absorber 10, and after the rich solvent contacts the vapor formed in the bottom 311 of the stripper 31, a poor solvent is formed and collected in the stripper 31. 311 at the bottom of the tower.

The above-mentioned heat exchanger group 21 comprises at least one heat exchanger 211, and if the heat exchanger group 21 includes more than two heat exchangers 211, each of the heat exchangers 211 can be connected in series or in parallel, But not limited thereto; in this embodiment, the heat exchanger group 21 includes two heat exchangers 211 connected in series. The heat exchanger group 21 communicates with the tower bottom 111 of the absorption tower 11 with a second flow channel 102a, and communicates with the tower top 310 of the stripping tower 31 with a third flow channel 102b, so that the absorption tower The rich solvent at the bottom 111 of the tower 11 is transported to the top 310 of the stripper 31; and the heat exchanger group 21 communicates with the bottom 311 of the stripper 31 with a fourth flow channel 103b, and the first The first channel 103a is further communicated with the heat exchanger group 21 after passing through the storage tank 12 of the absorption device 10, so the poor solvent at the bottom 311 of the stripping tower 31 can be stored in the storage tank 12, and then transported under pressure To the top 110 of the absorption tower 11 ; thus, the heat exchanger group 21 exchanges heat between the low-temperature rich solvent from the absorption unit 10 and the high-temperature lean solvent from the stripping unit 30 .

The above heat pump 20 mainly includes a condenser 201, an evaporator 202, a compressor 203 and a throttle valve 204, wherein the compressor 203 and the throttle valve 204 are connected in series between the condenser 201 and the evaporator 202 During this period, when the compressor 203 is activated, the condenser 201 produces high temperature, and the evaporator 202 produces low temperature; a cold end. The second channel 102a connected between the tower bottom 111 of the absorption device 10 and the heat exchanger group 21 passes through the condenser 201, so that the rich solvent transported here is heated up in advance, and then passes through the third channel. The flow channel 102b is sent to the tower top 310 of the stripper 31; and the first flow channel 103a connected between the storage tank 12 of the above-mentioned absorption device 10 and the heat exchanger group 21 passes through the evaporator 202, so that The poor solvent transported here is cooled in advance before being sent to the cooler 13 . The heat pump 20 means to achieve high efficiency in both directions of thermal energy transfer. High-efficiency equipment, the evaporator 202 of the heat pump 20 absorbs heat from a high-temperature heat source, and then releases heat from the condenser 201 to a low-temperature heat source; the parameter to measure the heat transfer capability of a heat pump 20 is the coefficient of performance (Coefficient of Performance, COP) , which is the ratio of the heat absorption flow rate from the high-temperature heat source to the input work of the heat pump; in this embodiment, the coefficient of performance of the heat pump 20 is 4, which means that one unit of energy is input to the heat pump per unit time, and four can be transferred from the high-temperature heat source. Unit heat to low temperature heat source, but not limited thereto.

In this embodiment, the carbon dioxide capture process of the carbon dioxide capture device 1 is as follows: the lean solvent flows from the storage tank 12 into the first flow channel 103a, and is pressurized and transported to the cooler 13 after being cooled to about 25°C Enter this absorption tower 11 from this tower top 110 of this absorption tower 11, but not limited to this; , the poor solvent is contacted with the flue gas to absorb carbon dioxide; the flue gas from which carbon dioxide is removed is discharged from the tower top 110 of the absorption tower 11, and at the same time, the poor solvent after contact becomes carbon dioxide-containing rich The solvent is collected at the bottom 111 of the absorption tower 11, and passes through the condenser 201 of the heat pump 20 through the second channel 102a.

Since the stripping operation is an endothermic process, a favorable condition is provided in advance to facilitate the stripping operation of the rich solvent in the stripping tower 31, and reduce the energy consumption of the reboiler 32 of the stripping device 30, The above-mentioned rich solvent must be heated to a specific high temperature. Therefore, during the process of being transported to the heat exchanger group 21, the rich solvent first passes through the condenser 201 of the heat pump 20 to raise the temperature before being transported through the second flow channel 102a to the heat exchanger group 21, and after heat exchange with the lean solvent from the stripping device 30, the temperature is further raised.

After the above-mentioned rich solvent is heated up in the heat exchanger group 21, it is transported to the top 310 of the stripper 31 through the third flow channel 102b, and enters the vapor formed in the stripper 31 and the bottom 311 of the stripper 31. Contact, the carbon dioxide dissolved in the rich solvent is stripped by steam, and discharged through the tower top 310 and further compressed and sealed. In this embodiment, the concentration of carbon dioxide discharged from the stripping tower can reach 99.9%; at the same time, The stripped rich solvent is collected at the bottom of the column 311 to form the lean solvent, a part of the lean solvent is refluxed to the reboiler 32 to reboil to about 120°C vapor and the rich solvent is stripped, but not The remaining part is sent to the heat exchanger group 21 through the fourth channel 103b.

Since the absorption operation is an exothermic process, in order to provide a favorable condition in advance to facilitate the absorption operation of the poor solvent in the absorption tower 11 and reduce the energy consumption of the cooler 13 of the absorption device 10, the above-mentioned poor solvent must Cool to a specific low operating temperature; therefore, when the lean solvent of the stripping device 30 is delivered to the heat exchanger group 21 through the fourth flow channel 103b, the lean solvent is in the heat exchanger 211, as described above Generally, it exchanges heat with the rich solvent and lowers the temperature; after that, in the process of transporting the heat exchanger group 21 to the absorption device 10 through the first channel 103a, the temperature is further lowered by the evaporator 202 of the heat pump 20, The lean solvent is transported back from the first channel 103a to the storage tank 12 in the absorption device 10 and recycled.

Please refer to Fig. 4, which is a statistical chart of energy consumption of the first embodiment of the low-energy carbon dioxide capture device of the present invention, and it needs to pay about 3.18 ± 200 million joules of energy consumption per ton of carbon dioxide capture, compared with Fig. 7 The energy consumption of the existing carbon dioxide capture device, the overall energy consumption of the carbon dioxide capture device 1 of the present invention can be reduced by about 14.19±5.43%; therefore, the present invention really saves energy consumption during carbon dioxide capture.

Please refer to again shown in Fig. 2, it is the second embodiment of the low energy consumption carbon dioxide capture device of the present invention, the carbon dioxide capture device 2 of this embodiment is roughly the same as the carbon dioxide capture device 1 of Fig. 1, except that A solar heat collector 22 is added in the carbon dioxide capture device 2, and the solar heat collector 22 is arranged between the absorption device 10 and the heat pump 20, and is connected with the bottom 111 of the absorption tower 11 and the heat exchanger group. The second flow channel 102a between 21 is connected to preheat the rich solvent generated in the bottom 111 of the absorption tower 11, and then preheat again through the second flow channel 102a through the condenser 201 of the heat pump.

Please refer to Fig. 5, which is a statistical chart of energy consumption of the second embodiment of the low-energy-consumption carbon dioxide capture device of the present invention, which requires 2.83 billion joules of energy consumption per ton of carbon dioxide captured, compared with the first embodiment of Fig. 4 The energy consumption of the carbon dioxide capture device in one embodiment is reduced by about 11.10±6.01%, further reducing the energy consumption of the carbon dioxide capture device 2 .

Please also refer to shown in Fig. 3 again, it is the third embodiment of the low energy consumption carbon dioxide capture device of the present invention, the carbon dioxide capture device 3 of this embodiment is roughly the same as the carbon dioxide capture device 2 of Fig. 2, but the solar energy The heat collector 22 is arranged between the heat pump 20 and the heat exchanger group 21, and communicates with the second flow passage 102a between the bottom 111 of the absorption tower 11 and the heat exchanger group 21, so as to pass through The rich solvent heated by the condenser 201 of the heat pump 20 is heated again.

Based on the above, it can be seen that the low-energy carbon dioxide capture device of the present invention is mainly equipped with a heat pump, which can pre-cool the high-temperature lean solvent from the stripping tower by virtue of the heat pump’s high-efficiency heat transfer characteristics; thus, the lean When the solvent enters the top of the absorption tower through the cooler, the cooler can make the poor solvent reach a low operating temperature with low energy consumption; The device can make the rich solvent reboil to a specific high operating temperature steam with lower energy consumption; through statistics, the energy consumption of the cooler and the reboiler saved by the present invention can indeed reduce the overall energy consumption; in addition, the present invention A solar heat collector is further installed in the carbon dioxide capture device to preheat the rich solvent, further reducing the energy consumption of the reboiler of the stripping device, so the low energy consumption carbon dioxide capture device of the present invention can reduce the carbon dioxide capture device The overall energy consumption can effectively improve the efficiency and economic benefits of carbon dioxide capture.

The above description is only an embodiment of the present invention, and does not limit the present invention in any form. Although the present invention has been disclosed as above with the embodiment, it is not intended to limit the present invention. Anyone with ordinary knowledge in the technical field, Without departing from the scope of the technical solution of the present invention, when the technical content disclosed above can be used to make some changes or modifications to equivalent embodiments with equivalent changes, but The content of the technical solution of the present invention, any simple modifications, equivalent changes and modifications made to the above embodiments according to the technical essence of the present invention still belong to the scope of the technical solution of the present invention.

1: Carbon dioxide capture device

10: Absorption device

11: Absorption tower

110: tower top

111: tower bottom

12: storage tank

13: Cooler

101: Smoke flow channel

102a: the second runner

102b: the third runner

103a: the first runner

103b: the fourth runner

20: Heat pump

21: Heat exchanger group

211: heat exchanger

201: condenser

202: evaporator

203: Compressor

204: throttle valve

30: Stripper

31: Stripper

310: tower top

311: tower bottom

32: Reboiler

Claims (10)

A carbon dioxide capture device with low energy consumption, comprising: an absorption device comprising an absorption tower and a cooler; wherein a top of the absorption tower is connected to the cooler, and a bottom of the absorption tower is generated A rich solvent; a stripping device comprising a stripping tower and a reboiler, wherein the reboiler is arranged at a bottom of the stripping tower, and the bottom of the stripping tower generates a lean solvent; A heat exchanger group communicates with a tower top and the tower bottom of the absorption tower through a first flow channel and a second flow channel, and communicates with the vaporizer with a third flow channel and a fourth flow channel respectively. A tower top of the column is connected to the bottom of the tower; wherein the second flow channel and the third flow channel are used to transport the rich solvent, and the first flow channel and the fourth flow channel are used to transport the poor solvent; and A heat pump is arranged between the absorption device and the heat exchanger group, and includes: a hot end for the passage of the second channel to heat the rich solvent at the bottom of the absorption tower; and a The cold end is for the passage of the first flow channel to cool the lean solvent at the bottom of the stripping tower; a solar heat collector is connected to the bottom of the absorption tower and the heat exchanger group The second flow channel is connected. The carbon dioxide capture device with low energy consumption as described in Claim 1, wherein the heat pump includes a condenser, an evaporator, a compressor and a throttle valve, wherein the compressor and the throttle valve are connected in series Between the condenser and the evaporator, and the condenser is the hot end of the heat pump, and the evaporator is the cold end of the heat pump. The low-energy carbon dioxide capture device as claimed in claim 1, wherein the heat exchanger system includes at least one heat exchanger. The low-energy carbon dioxide capture device as claimed in claim 3, wherein the heat exchanger group includes more than two heat exchangers, and each of the heat exchangers is connected in series. The carbon dioxide capture device with low energy consumption according to claim 3, wherein the heat exchanger group includes more than two heat exchangers, and each of the heat exchangers is connected in parallel. The carbon dioxide capture device with low energy consumption according to any one of claims 1 to 5, wherein the absorption device further includes a storage tank, which is arranged before the cooler, and the first flow channel communicates with the storage tank with this cooler. The low energy consumption carbon dioxide capture device as claimed in claim 1, wherein the solar heat collector is arranged between the absorption device and the heat pump. The low-energy-consumption carbon dioxide capture device according to claim 1, wherein the solar heat collector is arranged between the heat pump and the heat exchanger group. The low-energy-consumption carbon dioxide capture device as claimed in claim 6, wherein the solar heat collector is arranged between the absorption device and the heat pump. The low-energy-consumption carbon dioxide capture device according to claim 6, wherein the solar collector is arranged between the heat pump and the heat exchanger group.

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