WO2023035493A1

WO2023035493A1 - Flue gas purification system and cold energy comprehensive utilization process therefor

Info

Publication number: WO2023035493A1
Application number: PCT/CN2021/140607
Authority: WO
Inventors: 刘练波; 王焕君; 郭东方; 刘蓉; 范金航; 牛红伟; 郜时旺
Original assignee: 中国华能集团清洁能源技术研究院有限公司
Priority date: 2021-09-07
Filing date: 2021-12-22
Publication date: 2023-03-16
Also published as: CN113680179A; CN113680179B

Abstract

A flue gas purification system and a cold energy comprehensive utilization process therefor. The flue gas purification system comprises a COAP system (1), which is used for discharging flue gas after desulfurization and denitrification; and a carbon capture system (2), wherein a gas inlet thereof communicates with a gas discharge port of the COAP system (1) for use in removing carbon from the flue gas discharged from the COAP system (1). The flue gas purification system further comprises a cold energy utilization pipeline system (3), which is used to sequentially transport the flue gas discharged by the COAP system (1) to a condenser (28) and lean solution pipe (25) at the top of a regeneration tower (22) of the carbon capture system (2), so that the flue gas exchanges heat with discharged carbon dioxide and lean solution separately, and then enters an absorption tower (21) for decarbonization.

Description

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

cross reference

This application claims the priority of the Chinese patent application submitted to the China Patent Office on September 7, 2021 with the application number 202111044328.X and the title of the invention "A Flue Gas Purification System and Its Cooling Capacity Comprehensive Utilization Process", all of which The contents are incorporated by reference in this application.

technical field

The application relates to the technical field of power plant energy recovery, in particular to a flue gas purification system and a process for comprehensive utilization 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 in this application is to overcome the defect in the prior art that only adopts COAP technology to process the flue gas and then directly evacuate the flue gas and cannot meet the needs of flue gas evacuation, so as to provide 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 application 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 application also includes a steam heat utilization pipeline system, and the steam heat utilization pipeline 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.

This application 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 application has the following advantages:

1. The flue gas purification system provided by this application adopts the joint use of COAP system and carbon capture system, not only can use COAP process to remove SOx, NOx, Hg, HCl, HF, VOCs, etc. in the flue gas of power plants; At the same time, combined with the carbon capture system, the carbon in the flue gas can also be removed. The flue gas treated by the COAP system and the carbon capture system can achieve environmental protection and double carbon goals, and meet the needs of flue gas emptying.

2. The flue gas purification system provided by this application further adds a cooling energy utilization pipeline system, through which the cooling energy utilization pipeline system can be used to gradually utilize the cooling energy of the low-temperature flue gas generated by the COAP system, effectively realizing cooling energy recovery ; Specifically, the low-temperature flue gas produced by the COAP system is first utilized in the condenser of the carbon capture system for cooling, and then exchanges heat with the hot lean liquid in the carbon capture system, and then the secondary utilization of the cooling capacity, Finally, the flue gas that has undergone cold energy utilization is passed into the carbon capture system to remove carbon dioxide and then emptied; in this way, there is no need to add refrigeration equipment to the carbon capture system, and the cold energy utilization is more sufficient.

3. The flue gas purification system provided by this application has further added a steam heat utilization pipeline system, which can not only be applied to large-scale coal-fired power plant boilers, but also can be used to remove pollutants from various industrial exhaust gases such as waste incineration and coke oven kilns. 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 pipeline system can be used The high-quality steam from the steam turbine of the power plant can be utilized step by step as the temperature decreases in the COAP process and the carbon capture process, and the utilization rate of heat can be improved; after calculation, the direct operating cost of this application can be achieved under the near-zero emission index It 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 embodiments of the present application or the technical solutions in the prior art, the following will briefly introduce the accompanying drawings that need to be used in the description of the specific embodiments or prior art. Obviously, the accompanying drawings in the following description The drawings are some implementations of the present application, and those skilled in the art can obtain other drawings based on these drawings without creative work.

Fig. 1 is the overall structure schematic diagram of the flue gas purification system in the present application;

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

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

In the description of the present application, 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 application 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 limiting the present application. 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 this application, 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 can be mechanically connected or electrically connected; it can be directly connected or indirectly connected through an intermediary, and it can be the internal communication of two components. Those of ordinary skill in the art can understand the specific meanings of the above terms in this application in specific situations.

In addition, the technical features involved in the different embodiments of the present application described below may be combined as long as they do not constitute a 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 .

This application uses the COAP system and the carbon capture system in combination, not only can first 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 this application 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 created by the application.

Claims

A flue gas purification system is characterized in that it comprises:

COAP system (1), used to desulfurize and denitrify the flue gas and then discharge it;

The carbon capture system (2), the air inlet of which communicates with the exhaust port of the COAP system (1), is used for removing carbon in the flue gas discharged from the COAP system (1).
The flue gas purification system according to claim 1, characterized in that it further comprises a cold utilization piping system (3);

The carbon capture system (2) is a CO2 chemical absorption system with a condenser (28) and a lean liquid pipe (25); the cold utilization pipeline system (3) includes:

The first cold delivery pipeline (31) is used to transport the flue gas discharged from the COAP system (1) to the condenser (28) for cold utilization;

The second heat exchanger (32) is used to exchange heat with the lean liquid in the lean liquid pipe (25) and the flue gas discharged from the condenser (28);

The second cold delivery pipeline (33) is used to deliver the flue gas heat-exchanged by the second heat exchanger (32) to the air inlet of the carbon capture system (2).
The flue gas purification system according to claim 2, characterized in that the condenser (28) communicates with the second heat exchanger (32) through a low-temperature flue gas communication pipe (34).
The flue gas purification system according to claim 2 or 3, characterized in that the carbon capture system (2) further comprises:

The absorption tower (21) has an air inlet, an air outlet, a liquid inlet and a liquid outlet;

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

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

The two ends of the said lean liquid pipe (25) are connected with the liquid inlet of the absorption tower (21) and the liquid outlet of the regeneration tower (22) respectively, and the lean liquid pump (26) is arranged on the lean liquid pipe (25). .
The flue gas purification system according to claim 4, characterized in that, the carbon capture system (2) also includes a first heat exchanger for heat exchange between the rich liquid pipe (23) and the lean liquid pipe (25). Heater (29);

The lean liquid in the lean liquid pipe (25) first 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) .
According to the flue gas purification system according to claim 4, the COAP system (1) comprises a deduster (11), a desulfurization adsorption tower (12), a refrigerator (13), and a denitrification adsorption tower (14) connected in sequence; The gas outlet of the denitrification adsorption tower (14) communicates with the cold air inlet of the condenser (28) through the first cold delivery pipeline (31).
The flue gas purification system according to claim 6, characterized in that, the COAP system (1) also includes a flue gas cooler (15), and the flue gas cooler (15) is located between the dust remover (11) and The heat in the flue gas is recovered between the desulfurization adsorption towers (12); 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). ).
The flue gas purification system according to claim 6, characterized in that, the flue gas is flue gas discharged from a boiler, and the COAP system (1) also includes an air conditioning system between the boiler and the dust collector (11). device (17), the air preheater (17) is used for heat exchange between the flue gas discharged from the boiler and the air entering the boiler, and the flue gas enters the dust collector (11) after heat exchange in the air preheater (17) .
The flue gas purification system according to any one of claims 6-8, characterized in that it also includes a steam heat utilization pipeline system (4), and the steam heat utilization pipeline system (4) includes:

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 regeneration gas discharge pipe (42), one end communicates with the regeneration gas outlet of the desulfurization adsorption tower (12) and/or the denitrification adsorption tower (14), and the other end communicates with the air inlet of the reboiler (27);

One end of the steam recovery pipe (43) communicates with the gas outlet of the reboiler (27).
The flue gas purification system according to claim 9, characterized in that, the steam in the steam recovery pipe (43) and the flue gas in the second cold delivery pipeline (33) pass through the third heat exchanger (44) Discharge after heat exchange.
The process of using the flue gas purification system described in any one of claims 2-10 for comprehensive utilization of cooling capacity is characterized in that it includes:

The low-temperature flue gas discharged from the COAP system (1) first enters the condenser (28) of the carbon capture system (2) to cool down the discharged CO 2 gas, and then is mixed with the lean liquid in the carbon capture system (2). heat exchange, and finally enter the carbon capture system (2) to remove the CO 2 gas in the flue gas.