CN113680179B - A flue gas purification system and its cooling capacity comprehensive utilization process - Google Patents

Abstract

The invention discloses a flue gas purification system and a cold energy comprehensive utilization process thereof, wherein the flue gas purification system comprises a COAP system, and is used for desulfurizing and denitrating flue gas and then discharging the flue gas; and the air inlet of the carbon trapping system is communicated with the air outlet of the COAP system and is used for removing carbon in the flue gas exhausted by the COAP system. The flue gas purification system further comprises a cold energy utilization pipeline system, wherein the cold energy utilization pipeline system is used for sequentially conveying flue gas exhausted by the COAP system to a tower top condenser of a regeneration tower of the carbon trapping system and a lean liquid pipe, and the flue gas and exhausted carbon dioxide and lean liquid are subjected to heat exchange respectively and then enter an absorption tower for decarburization treatment. The flue gas treated by the COAP system and the carbon trapping system in a combined way can reach the aims of environmental protection and double carbon, meets the flue gas emptying requirement, and can make the cold energy of the flue gas exhausted by the COAP system more fully utilized.

Description

A flue gas purification system and its cooling capacity comprehensive utilization process

technical field

The invention relates to the technical field of power plant energy recovery, in particular to a flue gas purification system and a comprehensive utilization process of cooling capacity thereof.

Background technique

Low-temperature integrated pollutant removal technology (abbreviation: COAP technology) is a comprehensive treatment technology for flue gas pollutants. This technology is based on the principle of low _- temperature adsorption and denitrification of flue gas. At the same time, it also adsorbs SO ₃ , Hg, HCl, HF, VOCs and a small amount of NOx; the flue gas after desulfurization and dehumidification is cooled to the sub-zero temperature zone, and then enters the low-temperature denitrification adsorption tower, and NOx is deeply adsorbed and removed at low temperature to achieve pollution-oriented The two goals of "integrated removal" and "near-zero emission" of waste. For example: Chinese patent CN110743312A discloses a flue gas low-temperature adsorption denitrification system and process, which is a transformational technology to realize the purification of flue gas from industrial kilns such as coal-fired power generation, garbage and biomass power generation, and cement and steel.

After the COAP technology is used to treat the flue gas, the flue gas treated by the low-temperature denitrification adsorption tower is usually directly recycled for cooling and then emptied. However, the flue gas treated by the COAP technology also contains a large amount of CO ₂ . From the perspective of environmental protection and dual-carbon goals, direct evacuation is unreasonable and cannot meet the needs of flue gas evacuation.

Contents of the invention

Therefore, the technical problem to be solved by the present invention is to overcome the defect in the prior art that only the COAP technology is used to process the flue gas and then directly evacuate the flue gas and cannot meet the demand for flue gas evacuation, thereby providing a kind of flue gas that solves the above problems. Gas purification system and comprehensive utilization process of its cooling capacity.

A flue gas purification system, comprising:

The COAP system is used to desulfurize and denitrify the flue gas and then discharge it;

The carbon capture system, whose air inlet communicates with the exhaust port of the COAP system, is used to remove carbon from the flue gas discharged from the COAP system.

A flue gas purification system of the present invention also includes a cold utilization pipeline system;

The carbon capture system is a CO2 chemical absorption system with a condenser and a lean liquid pipe; the cooling utilization piping system includes:

The first cooling delivery pipeline is used to deliver the flue gas discharged from the COAP system to the condenser for cooling utilization;

The second heat exchanger is used to exchange heat between the flue gas discharged from the condenser and the lean liquid in the lean liquid pipe;

The second cold delivery pipeline is used to deliver the flue gas that has been heat-exchanged by the second heat exchanger to the air inlet of the carbon capture system.

The outlet of the condenser communicates with the second heat exchanger through a low-temperature flue gas communication pipe.

The carbon capture system also includes:

The absorption tower has an air inlet, an air outlet, a liquid inlet and a liquid outlet;

The regeneration tower has a liquid inlet and a liquid outlet, and a reboiler is arranged at the bottom thereof, and the condenser is arranged at its top position;

A liquid-rich pipe, the two ends of which are respectively connected with the liquid outlet of the absorption tower and the liquid inlet of the regeneration tower, and a rich liquid pump is arranged on it;

The two ends of the lean liquid pipe are respectively communicated with the liquid inlet of the absorption tower and the liquid outlet of the regeneration tower, and a lean liquid pump is arranged on the lean liquid pipe.

The carbon capture system also includes a first heat exchanger for heat exchange between the rich liquid pipe and the lean liquid pipe;

The lean liquid in the lean liquid pipe first exchanges heat with the gas in the second heat exchanger, and then exchanges heat with the rich liquid in the rich liquid pipe through the first heat exchanger.

The COAP system includes a dust collector, a desulfurization adsorption tower, a refrigerator, and a denitrification adsorption tower connected in sequence; the gas outlet of the denitrification adsorption tower communicates with the cold air inlet of the condenser through the first cold delivery pipeline.

The COAP system also includes a flue gas cooler, which is located between the dust collector and the desulfurization adsorption tower for recovering the heat in the flue gas; There are collection tanks for collecting condensed water in the flue gas.

The flue gas is the flue gas discharged from the boiler, and the COAP system also includes an air preheater located between the boiler and the dust collector, and the air preheater is used for heat exchange between the flue gas discharged from the boiler and the air entering the boiler, The flue gas enters the dust collector after exchanging heat in the air preheater.

A flue gas purification system of the present invention further includes a steam heat utilization piping system, and the steam heat utilization piping system includes:

The high-temperature steam delivery pipe communicates with the regeneration gas inlet of the desulfurization adsorption tower and/or the denitrification adsorption tower;

A regeneration gas discharge pipe, one end communicates with the regeneration gas outlet of the desulfurization adsorption tower and/or the denitrification adsorption tower, and the other end communicates with the inlet of the reboiler;

One end of the steam recovery pipe communicates with the gas outlet of the reboiler.

The steam in the steam recovery pipe is discharged after exchanging heat with the flue gas in the second cooling delivery pipeline.

The process of using the above-mentioned flue gas purification system for comprehensive utilization of cooling capacity includes:

The low-temperature flue gas discharged from the COAP system first enters the condenser of the carbon capture system to cool down the discharged CO2 gas, then exchanges heat with the lean liquid in the carbon capture system, and finally enters the carbon capture system for further processing. CO2 gas removal from flue gas.

The present invention also discloses a process for comprehensive utilization of heat by using the above-mentioned flue gas purification system, including:

The high-temperature steam of the steam turbine in the power plant is used as regeneration gas to first enter the desulfurization adsorption tower and/or denitrification adsorption tower to regenerate the adsorbent. The chemical adsorption liquid in the regeneration tower is heated in the boiler and then cooled to 100-150°C, then it exchanges heat with the low-temperature flue gas entering the carbon capture system and then cools down again before entering the subsequent steam utilization system.

Subsequent steam utilization systems include power plant heaters or/and deaerators.

The technical solution of the present invention has the following advantages:

1. A flue gas purification system provided by the present invention uses a COAP system and a carbon capture system in combination, not only can first use the COAP process to remove SOx, NOx, Hg, HCl, HF, and VOCs in the flue gas of a power plant At the same time, combined with the carbon capture system, the carbon in the flue gas can also be removed, and the flue gas treated by the COAP system and the carbon capture system can achieve environmental protection and double carbon targets, and meet the needs of flue gas emptying.

2. In the flue gas purification system provided by the present invention, a cooling capacity utilization pipeline system is further added, and the cooling capacity of the low-temperature flue gas generated by the COAP system is utilized step by step through the cooling capacity utilization pipeline system, effectively realizing cooling. energy recovery; specifically, the low-temperature flue gas produced by the COAP system is first used for cold energy in the condenser of the carbon capture system, and then exchanges heat with the hot lean liquid in the carbon capture system, and then the second level of cold energy Utilize, and finally pass the flue gas that has undergone cold energy utilization into the carbon capture system to remove carbon dioxide and then empty it; in this way, there is no need to add refrigeration equipment in the carbon capture system, and the cold energy utilization is more sufficient.

3. In the flue gas purification system provided by the present invention, a steam heat utilization pipeline system is further added, which can not only be applied to large-scale coal-fired power station boilers, but also can be used for waste incineration, coke oven kiln and other industrial exhaust gas. Pollutant removal treatment, especially when used in large-scale coal-fired power plant boilers, can improve the competitiveness of thermal power plants, and can achieve the triple goals of net zero pollutant emissions, carbon dioxide emission reduction, and comprehensive energy utilization; the steam heat utilization piping system The high-quality steam from the steam turbine of the power plant can be used to realize step-by-step utilization as the temperature decreases in the COAP process and the carbon capture process, and improve the utilization rate of heat; after calculation, under the realization of near-zero emission indicators, the direct steam of the present invention The operating cost is only 0.015-0.02 yuan/kWh, which can be completely covered by the conventional ultra-low emission desulfurization and denitrification subsidy electricity price.

Description of drawings

In order to more clearly illustrate the specific implementation of the present invention or the technical solutions in the prior art, the following will briefly introduce the accompanying drawings that need to be used in the specific implementation or description of the prior art. Obviously, the accompanying drawings in the following description The drawings show some implementations of the present invention, and those skilled in the art can obtain other drawings based on these drawings without any creative effort.

Fig. 1 is the overall structure schematic diagram of a kind of flue gas purification system among the present invention;

Fig. 2 is a structural diagram of the location of the carbon capture system with the cooling utilization pipeline system in the present invention.

Explanation of reference signs:

1-COAP system, 2-carbon capture system, 3-cold utilization pipeline system, 4-steam heat utilization pipeline system;

11-dust collector, 12-desulfurization adsorption tower, 13-refrigerator, 14-denitration adsorption tower, 15-flue gas cooler, 16-collection tank, 17-air preheater;

21-absorption tower, 22-regeneration tower, 23-rich liquid pipe, 24-rich liquid pump, 25-lean liquid pipe, 26-lean liquid pump, 27-reboiler, 28-condenser, 29-first exchange Heater;

31-the first cold delivery pipeline, 32-the second heat exchanger, 33-the second cold delivery pipeline, 34-the low-temperature flue gas connecting pipe;

41-high temperature steam delivery pipe, 42-regeneration gas discharge pipe, 43-steam recovery pipe, 44-third heat exchanger.

Detailed ways

The technical solutions of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Apparently, the described embodiments are part of the embodiments of the present invention, but not all of them. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "upper", "lower", "front", "rear", "inner", "outer" etc. are based on the Orientation or positional relationship is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation of the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and should not be construed as indicating or implying relative importance.

In the description of the present invention, it should be noted that unless otherwise specified and limited, the terms "installation", "connection" and "connection" should be understood in a broad sense, for example, it can be a fixed connection or a detachable connection. Connected, or integrally connected; it may be mechanically connected or electrically connected; it may be directly connected or indirectly connected through an intermediary, and it may be the internal communication of two components. Those of ordinary skill in the art can understand the specific meanings of the above terms in the present invention in specific situations.

In addition, the technical features involved in the different embodiments of the present invention described below may be combined with each other as long as there is no conflict with each other.

Example 1

A flue gas purification system includes a COAP system 1 and a carbon capture system 2 whose air inlet communicates with the exhaust port of the COAP system 1 . Among them, the COAP system 1 is used to desulfurize and denitrify the flue gas and then discharge it, and the carbon capture system 2 is used to remove carbon in the flue gas discharged from the COAP system 1 .

The present invention uses the COAP system and the carbon capture system in combination, not only can use the COAP process to remove SOx, NOx, Hg, HCl, HF, VOCs, etc. in the flue gas of the power plant; at the same time, combined with the carbon capture system, it can also The carbon in the flue gas can be removed, and the flue gas treated by the COAP system and the carbon capture system can achieve the goal of environmental protection and double carbon, and meet the needs of flue gas emptying.

The COAP system 1 in this embodiment may be a conventional COAP system, or a COAP system with an optimized structure. The carbon capture system 2 can be one of several categories such as chemical absorption, physical absorption, physical adsorption, membrane separation, and cryogenic separation. As long as the carbon in the flue gas discharged from the COAP system can be removed, the flue gas evacuation requirement in the present invention can be met.

Example 2

In this embodiment, the structure of a flue gas purification system is further optimized on the basis of Embodiment 1. In this embodiment, the carbon capture system 2 is a CO2 chemical absorption system, and a cooling capacity utilization pipeline system 3 is added at the same time. Effectively and rationally apply the cooling capacity in the low-temperature flue gas discharged from the COAP system 1, as shown in Figure 2, the details are as follows:

The carbon capture system 2 includes an absorption tower 21 , a regeneration tower 22 , a rich liquid pipe 23 , a rich liquid pump 24 , a lean liquid pipe 25 , a lean liquid pump 26 , a reboiler 27 and a condenser 28 . Wherein, the absorption tower 21 has an air inlet, a gas outlet, a liquid inlet and a liquid outlet, and the regeneration tower 22 has a liquid inlet, a liquid outlet and an exhaust port; the bottom of the regeneration tower 22 is provided with a reboiler 27, and the top exhaust A condenser 28 is set at the mouth position; the two ends of the rich liquid pipe 23 are connected with the liquid outlet of the absorption tower 21 and the liquid inlet of the regeneration tower 22 respectively, and a rich liquid pump 24 is arranged on it; the two ends of the poor liquid pipe 25 are respectively connected with The liquid inlet of the absorption tower 21 communicates with the liquid outlet of the regeneration tower 22, and a lean liquid pump 26 is arranged on it, as shown in FIG. 2 .

As shown in FIG. 1 , the COAP system 1 includes a dust collector 11 , a desulfurization adsorption tower 12 , a refrigerator 13 , and a denitrification adsorption tower 14 connected in sequence.

The cooling utilization pipeline system 3 includes a first cooling delivery pipeline 31, a second heat exchanger 32, a low-temperature flue gas communication pipe 34, and a second cooling delivery pipeline 33; wherein, the first cooling delivery pipeline Both ends of 31 communicate with the gas outlet of the denitrification adsorption tower 14 and the cold air inlet of the condenser 28 respectively, and are used to transport the flue gas discharged from the COAP system 1 to the condenser 28 for cooling utilization. The second heat exchanger 32 respectively includes a flue gas pipeline and a lean liquid pipeline for exchanging heat between the flue gas discharged from the condenser 28 and the lean liquid in the lean liquid pipe 25 . The low-temperature flue gas communication pipe 34 communicates with the cold air outlet of the condenser 28 and the flue gas inlet of the second heat exchanger 32 respectively, and is used to transport the low-temperature flue gas in the condenser 28 to the second heat exchanger 32 for heat exchange . The second cold delivery pipeline 33 communicates with the flue gas outlet in the second heat exchanger 32 and the air inlet of the absorption tower 21 in the carbon capture system 2 respectively, and is used for further heat exchange of the second heat exchanger 32 The heated flue gas is sent to the carbon capture system 2 for carbon removal.

Through the optimization of the above structure, the cooling capacity of the low-temperature flue gas discharged from the COAP process can be fully utilized.

In order to better utilize the heat in the lean liquid, the carbon capture system 2 also includes a first heat exchanger 29 for heat exchange between the rich liquid pipe 23 and the lean liquid pipe 25, as shown in Figure 2 As shown; the lean liquid in the lean liquid pipe 25 first exchanges heat with the flue gas in the second heat exchanger 32 , and then exchanges heat with the rich liquid in the rich liquid pipe 23 through the first heat exchanger 29 .

Due to the high temperature of the flue gas entering the COAP system 1, in order to avoid energy waste, the COAP system 1 also includes a flue gas cooler 15, which is located between the dust remover 11 and the desulfurization adsorption tower 12 It is used to cool the flue gas while recovering the heat in the flue gas, and the recovered heat can be used for other applications. A collection tank 16 for collecting condensed water in the flue gas is also provided between the flue gas cooler 15 and the desulfurization adsorption tower 12 , as shown in FIG. 1 . When the flue gas is the flue gas discharged from the boiler, the COAP system 1 also includes an air preheater 17 between the boiler and the dust collector 11, and the air preheater 17 is used for the flue gas discharged from the boiler and entering the boiler The air performs heat exchange, and the flue gas enters the dust collector 11 after exchanging heat in the air preheater 17 .

Example 3

This embodiment further optimizes the structure of a flue gas purification system on the basis of embodiment 2. In this embodiment, a steam heat utilization pipeline system 4 is added, which can utilize steam of different qualities in the power plant step by step , to improve the energy utilization rate, as follows:

The steam heat utilization pipeline system 4 includes a high temperature steam delivery pipe 41 , a regeneration gas discharge pipe 42 , a steam recovery pipe 43 and a third heat exchanger 44 . Among them, the high-temperature steam delivery pipe 41 communicates with the regeneration gas inlet of the desulfurization adsorption tower 12 and/or the denitrification adsorption tower 14; the high-temperature steam discharged from the steam turbine of the power plant up to 300-350 ° C is used as the regeneration gas, and the regeneration gas is used as the regeneration gas After desulfurization adsorption tower 12 and/or denitrification adsorption tower 14 regenerates the adsorbent, the temperature of the regenerated gas is lowered to 200-300°C. One end of the regeneration gas discharge pipe 42 is communicated with the regeneration gas outlet of the desulfurization adsorption tower 12 and/or the denitrification adsorption tower 14, and the other end is communicated with the inlet of the reboiler 27; In the reboiler 27, the lean liquid in the regeneration tower 22 is heated to promote the removal of carbon dioxide in the lean liquid. After the lean liquid is heated, the temperature of the steam discharged from the reboiler 27 is further reduced to 100-150°C, about 120°C. The steam recovery pipe 43 is used to transport the high-temperature gas output from the reboiler 27 to the rear end of the cold utilization pipeline system 3 to continue to exchange heat with the flue gas transported into the carbon capture system 2; specifically, the steam The steam in the recovery pipe 43 and the flue gas in the second cooling delivery pipeline 33 pass through the third heat exchanger 44 and then discharged, and the temperature of the steam after the heat exchange can still reach about 80-90°C. In order to make better use of this part of steam heat, the exhausted steam can also be sent to the subsequent steam utilization system for utilization, such as: power plant heater or/and deaerator.

Apparently, the above-mentioned embodiments are only examples for clear description, rather than limiting the implementation. For those of ordinary skill in the art, other changes or changes in different forms can be made on the basis of the above description. It is not necessary and impossible to exhaustively list all the implementation manners here. And the obvious changes or changes derived therefrom are still within the scope of protection of the present invention.

Claims (9)

1. A flue gas cleaning system, comprising:

the COAP system (1) is used for desulfurizing and denitrating the flue gas and then discharging the flue gas;

the carbon trapping system (2) is communicated with the exhaust port of the COAP system (1) and is used for removing carbon in the flue gas exhausted by the COAP system (1);

the system also comprises a cold energy utilization pipeline system (3);

the carbon capture system (2) is CO with a condenser (28) and a lean liquid pipe (25) ₂ A chemical absorption system; the cold energy utilization pipeline system (3) comprises:

the first cold energy conveying pipeline (31) is used for conveying the flue gas exhausted by the COAP system (1) into the condenser (28) for cold energy utilization;

the second heat exchanger (32) is used for exchanging heat between the flue gas discharged by the condenser (28) and the lean liquid in the lean liquid pipe (25);

the second cold energy conveying pipeline (33) is used for conveying the flue gas subjected to heat exchange by the second heat exchanger (32) to an air inlet of the carbon capture system (2);

the condenser (28) is communicated with the second heat exchanger (32) through a low-temperature flue gas communicating pipe (34);

the carbon capture system (2) also comprises a first heat exchanger (29) for heat exchange between the rich liquid pipe (23) and the lean liquid pipe (25);

the lean liquid in the lean liquid pipe (25) exchanges heat with the gas in the second heat exchanger (32) firstly, and then exchanges heat with the rich liquid in the rich liquid pipe (23) through the first heat exchanger (29).

2. A flue gas cleaning system according to claim 1, wherein the carbon capture system (2) further comprises:

an absorption tower (21) provided with an air inlet, an air outlet, a liquid inlet and a liquid outlet;

a regeneration tower (22) with a liquid inlet and a liquid outlet, wherein the bottom of the regeneration tower is provided with a reboiler (27), and the condenser (28) is arranged at the top position of the regeneration tower;

the two ends of the rich liquid pipe (23) are respectively communicated with the liquid outlet of the absorption tower (21) and the liquid inlet of the regeneration tower (22), and a rich liquid pump (24) is arranged on the rich liquid pipe;

both ends of the lean liquid pipe (25) are respectively communicated with a liquid inlet of the absorption tower (21) and a liquid outlet of the regeneration tower (22), and a lean liquid pump (26) is arranged on the lean liquid pipe (25).

3. A flue gas cleaning system according to claim 2, wherein the carbon capture system (2) further comprises a first heat exchanger (29) for heat exchange between the rich liquid pipe (23) and the lean liquid pipe (25);

the lean liquid in the lean liquid pipe (25) exchanges heat with the gas in the second heat exchanger, and then exchanges heat with the rich liquid in the rich liquid pipe (23) through the first heat exchanger (29).

4. A flue gas purification system according to claim 2, wherein the COAP system (1) comprises a dust remover (11), a desulfurization adsorption tower (12), a refrigerator (13) and a denitration adsorption tower (14) which are sequentially communicated; the gas outlet of the denitration adsorption tower (14) is communicated with the cold air inlet of the condenser (28) through a first cold air conveying pipeline (31).

5. A flue gas cleaning system according to claim 4, wherein the COAP system (1) further comprises a flue gas cooler (15), the flue gas cooler (15) being located between the dust separator (11) and the desulfurization absorption tower (12) for recovering heat in the flue gas; a collecting tank (16) for collecting condensed water in the flue gas is also arranged between the flue gas cooler (15) and the desulfurization adsorption tower (12).

6. The flue gas purification system according to claim 4, wherein the flue gas is flue gas exhausted from a boiler, the COAP system (1) further comprises an air preheater (17) located between the boiler and the dust remover (11), the air preheater (17) is used for exchanging heat between the flue gas exhausted from the boiler and air entering the boiler, and the flue gas enters the dust remover (11) after being exchanged in the air preheater (17).

7. A flue gas cleaning system according to any one of claims 4-6, further comprising a steam heat utilization pipe system (4), said steam heat utilization pipe system (4) comprising:

a high-temperature steam delivery pipe (41) communicated with a regeneration gas inlet of the desulfurization adsorption tower (12) and/or the denitration adsorption tower (14);

one end of a regenerated gas discharge pipe (42) is communicated with a regenerated gas outlet of the desulfurization adsorption tower (12) and/or the denitration adsorption tower (14), and the other end of the regenerated gas discharge pipe is communicated with a gas inlet of a reboiler (27);

and one end of the steam recovery pipe (43) is communicated with the air outlet of the reboiler (27).

8. A flue gas cleaning system according to claim 7, wherein the steam in the steam recovery pipe (43) exchanges heat with the flue gas in the second cold energy transfer line (33) and is discharged by a third heat exchanger (44).

9. A process for comprehensive utilization of cold energy by using a flue gas purification system according to any one of claims 1 to 8, comprising:

the low-temperature flue gas exhausted by the COAP system (1) firstly enters a condenser (28) of the carbon trapping system (2) to discharge CO ₂ After the gas is cooled, the gas exchanges heat with lean liquid in the carbon trapping system (2), and finally enters the carbon trapping system (2) to carry out CO in the flue gas ₂ And (3) removing gas.

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