A low-carbon emission coal-fired system and control method for flue gas energy utilization

Abstract

The present invention discloses a low-carbon emission coal-fired system and control method for flue gas energy utilization. The system includes a flue gas water absorption system and a flue gas carbon dioxide absorption system, which fully utilizes the medium-temperature energy contained in the flue gas of the coal-fired system. The exhaust smoke of the boiler becomes clean dry flue gas after passing through a water absorption tower and a carbon dioxide absorption tower. The feed water coming out of the condenser absorbs the waste heat of the water absorption system and the carbon dioxide absorption system, thereby reducing the impact of the carbon capture system on the coal-fired system. The input of the system is flue gas, which changes under the influence of the unit load. When the input flue gas volume changes, the flow rate of the solution supplementary liquid and / or the alcohol amine supplementary liquid and / or the flow rate of steam is adjusted to meet the absorption rate of water and carbon dioxide. The present invention reduces the impact of the coupled carbon capture system on the coal-fired unit by utilizing the energy of the flue gas and absorbing the moisture and carbon dioxide in the flue gas, providing a direction for clean coal-fired technology.

Description

Technical Field

[0001] The present invention belongs to the field of thermal power plants, and in particular, relates to a low-carbon emission coal-fired system and a control method for utilizing flue gas energy. Background Art

[0002] Global energy consumption has grown rapidly with the continuous development of the world economy. In 2021, the global electricity demand was 27369.4 trillion kWh, of which coal-fired power generation accounted for 36%. The International Energy Agency (IEA) predicts that in 2040, the global use of fossil fuels will account for 74% of the total primary energy use, and a large amount of greenhouse gases (CO 2 ) into the atmosphere, will break the dynamic balance of the carbon cycle, triggering a series of global problems such as glacier melting, global warming, drought, etc. From the perspective of the structure of carbon emission sources, the power industry is CO 2 One of the main sources of emissions, with large emissions and rapid growth. Therefore, it is crucial to develop low-carbon energy and technologies such as coal gasification, biomass energy, and carbon capture and storage.

[0003] Carbon capture and storage mainly includes three stages: capture, transportation and storage. CO2 is captured and separated from emission sources such as energy utilization, industrial processes or air, and transported to suitable sites for utilization or storage through tank trucks, pipelines, ships, etc., ultimately achieving CO2 emission reduction. Existing carbon capture technologies include pre-combustion capture, post-combustion capture and oxygen-enriched combustion. In the power industry, carbon emissions mainly come from the combustion of fossil fuels. Post-combustion carbon capture technology based on amine-based solvents is more suitable for low-concentration CO2 capture. Summary of the invention

[0004] In order to reduce the impact of the coupled carbon capture system on the coal-fired unit, the purpose of the present invention is to provide a low-carbon emission coal-fired system and control method for flue gas energy utilization, the system includes a flue gas water absorption system and a flue gas carbon dioxide absorption system, wherein the flue gas cooler component of the flue gas carbon dioxide absorption system utilizes the medium-temperature waste heat contained in the flue gas of the coal-fired system, and at the same time, the flue gas carbon dioxide system can fully absorb the carbon dioxide in the flue gas, so that the unit's pollutant emissions are reduced. The exhaust gas of the boiler becomes clean dry flue gas after passing through the water absorption tower and the carbon dioxide absorption tower, and the feed water from the condenser absorbs the waste heat of the water absorption system and the carbon dioxide absorption system, thereby reducing the impact of the carbon capture system on the coal-fired system.

[0005] In order to achieve the above object, the present invention adopts the following technical solution:

[0006] A low-carbon emission coal-fired system for flue gas energy utilization and a control method thereof, wherein the low-carbon emission coal-fired system for flue gas energy utilization comprises a flue gas water absorption system and a flue gas carbon dioxide absorption system;

[0007] The flue gas water absorption system comprises an induced draft fan 1, a flue gas cooler 2, a water absorption tower 3, a dilute solution pump 4, a dilute solution separator 5, a concentrated solution mixer 6, a dilute and concentrated solution heat exchanger 7, a concentrated solution regeneration tower 8, a concentrated solution pump 9 and a solution mixer 20, a feed water mixer 19, a feed water heater 11 and a feed water heater 12;

[0008] The flue gas carbon dioxide absorption system comprises a flue gas cooler 13, a carbon dioxide absorption tower 14, a lean liquid cooler 15, a rich liquid pump 16, a lean and rich liquid heat exchanger 17, a carbon dioxide desorption tower 18 and an alcohol amine solution mixer 19;

[0009] In the flue gas water absorption system: the flue gas a coming out of the boiler is connected to the inlet of the induced draft fan 1, the outlet of the induced draft fan 1 is connected to the hot end inlet of the flue gas cooler 2, the hot end outlet of the flue gas cooler 2 is connected to the bottom inlet of the water absorption tower 3, the top outlet of the water absorption tower 3 is connected to the hot end inlet of the flue gas cooler 13, the bottom outlet of the water absorption tower 3 is connected to the inlet of the dilute solution pump 4, the outlet of the dilute solution pump 4 is connected to the inlet of the dilute solution separator 5, the two outlets of the dilute solution separator 5 are respectively connected to the inlet of the concentrated solution mixer 6 and the cold end inlet of the dilute-concentrate solution heat exchanger 7, and the dilute-concentrate solution is connected to the inlet of the dilute-concentrate solution. The cold end outlet of the solution heat exchanger 7 is connected to the inlet of the concentrated solution regeneration tower 8, the top outlet of the concentrated solution regeneration tower 8 is connected to the hot end inlet of the feed water heater 12, the bottom outlet of the concentrated solution regeneration tower 8 is connected to the inlet of the concentrated solution pump 9, the outlet of the concentrated solution pump 9 is connected to the hot end inlet of the dilute concentrated solution heat exchanger 7, the hot end outlet of the dilute concentrated solution heat exchanger 7 is connected to the hot end inlet of the feed water heater 11 through the concentrated solution mixer 6, the hot end outlet of the feed water heater 11 is connected to the inlet of the solution mixer 20, and the outlet of the solution mixer 20 is connected to the inlet of the water absorption tower 3;

[0010] In the flue gas carbon dioxide absorption system: the hot end outlet of the flue gas cooler 13 is connected to the bottom inlet of the carbon dioxide absorption tower 14, the bottom outlet of the carbon dioxide absorption tower 14 is connected to the inlet of the rich liquid pump 16, the outlet of the rich liquid pump 16 is connected to the cold end inlet of the lean-rich liquid heat exchanger 17, the cold end outlet of the lean-rich liquid heat exchanger 17 is connected to the inlet of the carbon dioxide desorption tower 18, the top outlet of the carbon dioxide desorption tower 18 discharges carbon dioxide, the bottom outlet of the carbon dioxide desorption tower 18 is connected to the hot end inlet of the lean-rich liquid heat exchanger 17, the hot end outlet of the lean-rich liquid heat exchanger 17 is connected to the hot end inlet of the lean liquid cooler 15, the hot end outlet of the lean liquid cooler 15 is connected to the inlet of the alcoholamine solution mixer 19, and the outlet of the alcoholamine solution mixer 19 is connected to the solvent inlet of the carbon dioxide absorption tower 14.

[0011] The water flow in the flue gas carbon capture system for flue gas energy utilization is as follows: the water feed b from the condenser outlet flows into the flue gas cooler 13 for heating, the water feed flowing out of the flue gas cooler 13 flows into the water feed separator 10, part of the water feed flowing out of the water feed separator 10 enters the lean liquid cooler 15, and the other part flows into the water feed heater 11, the water feed entering the lean liquid cooler 15 enters the flue gas cooler 2, and finally flows into the water feed mixer 19, while the water feed flowing into the water feed heater 11 flows into the water feed heater 12, and then flows into the condenser of the carbon dioxide desorption tower 18, and finally flows into the water feed mixer 19, and the water feed c collected in the water feed mixer 19 flows into the water feed heater system.

[0012] The solution adopted by the flue gas water absorption system is a calcium chloride solution; the solution adopted by the flue gas carbon dioxide absorption system is an alcohol amine solution.

[0013] The high-temperature and high-pressure steam d flowing into the low-carbon emission coal-fired system for flue gas energy utilization flows into the reboiler of the carbon dioxide desorption tower 18, the medium-temperature feed water coming out of the reboiler flows into the reboiler of the concentrated solution regeneration tower 8, the feed water from the reboiler of the concentrated solution regeneration tower 8 flows into the feed water mixer 19, and the feed water c collected in the feed water mixer 19 flows into the feed water heater system.

[0014] The flue gas pressure at the outlet of the induced draft fan 1 ranges from 140 to 150 kPa. The operating pressure of the water absorption tower 3 is lower than the pressure of the flue gas at the outlet of the induced draft fan 1. Due to the pressure difference, the flue gas can flow into the water system tower.

[0015] The pressure range of the concentrated solution regeneration tower 8 is 30-40 kPa, and the outlet pressure range of the concentrated solution pump 9 is 200-250 kPa. The water in the dilute solution entering the concentrated solution regeneration tower 8 can be quickly resolved, and the resolved concentrated solution can quickly flow out of the concentrated solution regeneration tower 8.

[0016] The pressure range of the carbon dioxide absorption tower 14 is 100-120 kPa, and the pressure range of the rich liquid at the outlet of the rich liquid pump 16 is 170-220 kPa. When the pressure range is 100-120 kPa, carbon dioxide can react with the alcohol amine solution. The function of the rich liquid pump is to pressurize the solution. The reason for selecting 170-220 kPa is that this pressure range can enable the solution to overcome the pipeline resistance and smoothly enter the carbon dioxide desorption tower 18.

[0017] The operating pressure range of the carbon dioxide desorption tower 18 is 160-200 kPa. The rich liquid can desorb carbon dioxide in the carbon dioxide desorption tower 18. The operating pressure of the carbon dioxide desorption tower 18 is less than the outlet pressure of the rich liquid pump 16, so that the rich liquid can flow into the carbon dioxide desorption tower 18.

[0018] The present invention also provides a control method for a low-carbon emission coal-fired system utilizing flue gas energy, which adjusts the load change of the unit, including:

[0019] Step 1: When the system starts to run, the ratio and flow of the solutions in the flue gas water absorption system and the flue gas carbon dioxide absorption system are adjusted by adjusting the ratio of the inlet flow of the alcohol amine solution mixer 19 and the inlet flow of the solution mixer 20 to obtain the absorption rate of water and carbon dioxide;

[0020] Step 2: When the flue gas volume of the flue gas a from the boiler changes, the flow rates of the solution replenishing liquid and the alcohol amine replenishing liquid and the flow rate of the high-temperature and high-pressure steam d are adjusted to meet the absorption rate of water and carbon dioxide. Specifically, when the flue gas volume of the flue gas a from the boiler increases, the flow rates of the solution replenishing liquid and the alcohol amine replenishing liquid at the inlets of the alcohol amine solution mixer 19 and the solution mixer 20 are increased, and the flow rate of the high-temperature and high-pressure steam d is increased at the same time; when the flue gas volume of the flue gas a from the boiler decreases, the flow rate of the high-temperature and high-pressure steam d is reduced;

[0021] Step 3: The temperature of the feed water c collected in the feed water mixer 19 is controlled by adjusting the ratio of the feed water from the outlet of the feed water separator 10 entering the lean liquid cooler 15 and the feed water heater 11 .

[0022] Compared with the prior art, the present invention has the following advantages:

[0023] (1) The present invention adopts a flue gas water absorption system and a flue gas carbon dioxide absorption system, and uses a heat exchanger to heat the feed water at the outlet of the condenser with the waste heat of the flue gas and the heat generated by the chemical reaction changes in the two absorption processes. Therefore, the present invention not only fully utilizes the waste heat in the flue gas but also fully utilizes the substances in the flue gas;

[0024] (2) The present invention is based on the principle of absorption method. By controlling the inlet flow rate of the alcohol amine solution mixer 19 and the solution mixer 20, the absorption rate of carbon dioxide can be controlled when the load rate changes. Therefore, the present invention can be adapted to operation under various load conditions.

[0025] (3) The present invention reduces the proportion of other components in the flue gas, improves the absorption rate of the carbon dioxide absorption system, reduces the moisture at the inlet of the carbon dioxide absorption tower, and increases the contact between carbon dioxide and the absorbent, thereby promoting the absorption of carbon dioxide. Therefore, the present invention reduces the irreversibility of the carbon dioxide system. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 Schematic diagram of a large-scale carbon capture system for flue gas energy utilization.

[0027] Figure 2 Schematic diagram of the connection structure of the thermal power generation system provided in an embodiment of the present invention.

[0028] Attached Figure 2 Marking instructions: 1-1 is the boiler, 1-2 is the high-pressure cylinder, 1-3 is the medium-pressure cylinder, 1-4 is the regenerative steam turbine, 1-5 is the low-pressure cylinder, 1-6 is the condenser, 1-7 is the condensate pump, 1-8 is the deaerator, and 1-9 is the regenerative heater.

[0029] Figure 3 is the change in carbon capture absorption rate. DETAILED DESCRIPTION

[0030] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0031] Figure 1 Schematic diagram of a large-scale carbon capture system for flue gas energy utilization, the system comprising a flue gas water absorption system and a flue gas carbon dioxide absorption system;

[0032] The flue gas water absorption system comprises an induced draft fan 1, a flue gas cooler 2, a water absorption tower 3, a dilute solution pump 4, a dilute solution separator 5, a concentrated solution mixer 6, a dilute and concentrated solution heat exchanger 7, a concentrated solution regeneration tower 8, a concentrated solution pump 9 and a solution mixer 20, a feed water mixer 19, a feed water heater 11 and a feed water heater 12;

[0033] The flue gas carbon dioxide absorption system comprises a flue gas cooler 13, a carbon dioxide absorption tower 14, a lean liquid cooler 15, a rich liquid pump 16, a lean and rich liquid heat exchanger 17, a carbon dioxide desorption tower 18 and an alcohol amine solution mixer 19;

[0034] In the flue gas water absorption system: the flue gas a coming out of the boiler is connected to the inlet of the induced draft fan 1, the outlet of the induced draft fan 1 is connected to the hot end inlet of the flue gas cooler 2, the hot end outlet of the flue gas cooler 2 is connected to the bottom inlet of the water absorption tower 3, the top outlet of the water absorption tower 3 is connected to the hot end inlet of the flue gas cooler 13, the bottom outlet of the water absorption tower 3 is connected to the inlet of the dilute solution pump 4, the outlet of the dilute solution pump 4 is connected to the inlet of the dilute solution separator 5, the two outlets of the dilute solution separator 5 are respectively connected to the inlet of the concentrated solution mixer 6 and the cold end inlet of the dilute-concentrate solution heat exchanger 7, and the dilute-concentrate solution is connected to the inlet of the dilute-concentrate solution. The cold end outlet of the solution heat exchanger 7 is connected to the inlet of the concentrated solution regeneration tower 8, the top outlet of the concentrated solution regeneration tower 8 is connected to the hot end inlet of the feed water heater 12, the bottom outlet of the concentrated solution regeneration tower 8 is connected to the inlet of the concentrated solution pump 9, the outlet of the concentrated solution pump 9 is connected to the hot end inlet of the dilute concentrated solution heat exchanger 7, the hot end outlet of the dilute concentrated solution heat exchanger 7 is connected to the hot end inlet of the feed water heater 11 through the concentrated solution mixer 6, the hot end outlet of the feed water heater 11 is connected to the inlet of the solution mixer 20, and the outlet of the solution mixer 20 is connected to the inlet of the water absorption tower 3;

[0035] In the flue gas carbon dioxide absorption system: the hot end outlet of the flue gas cooler 13 is connected to the bottom inlet of the carbon dioxide absorption tower 14, the bottom outlet of the carbon dioxide absorption tower 14 is connected to the inlet of the rich liquid pump 16, the outlet of the rich liquid pump 16 is connected to the cold end inlet of the lean-rich liquid heat exchanger 17, the cold end outlet of the lean-rich liquid heat exchanger 17 is connected to the inlet of the carbon dioxide desorption tower 18, the top outlet of the carbon dioxide desorption tower 18 discharges carbon dioxide, the bottom outlet of the carbon dioxide desorption tower 18 is connected to the hot end inlet of the lean-rich liquid heat exchanger 17, the hot end outlet of the lean-rich liquid heat exchanger 17 is connected to the hot end inlet of the lean liquid cooler 15, the hot end outlet of the lean liquid cooler 15 is connected to the inlet of the alcoholamine solution mixer 19, and the outlet of the alcoholamine solution mixer 19 is connected to the solvent inlet of the carbon dioxide absorption tower 14.

[0036] The water flow in the flue gas carbon capture system for flue gas energy utilization is as follows: the water feed b from the condenser outlet flows into the flue gas cooler 13 for heating, the water feed flowing out of the flue gas cooler 13 flows into the water feed separator 10, part of the water feed flowing out of the water feed separator 10 enters the lean liquid cooler 15, and the other part flows into the water feed heater 11, the water feed entering the lean liquid cooler 15 enters the flue gas cooler 2, and finally flows into the water feed mixer 19, while the water feed flowing into the water feed heater 11 flows into the water feed heater 12, and then flows into the condenser of the carbon dioxide desorption tower 18, and finally flows into the water feed mixer 19, and the water feed c collected in the water feed mixer 19 flows into the water feed heater system.

[0037] The solution adopted by the flue gas water absorption system is a calcium chloride solution; the solution adopted by the flue gas carbon dioxide absorption system is an alcohol amine solution.

[0038] The high-temperature and high-pressure steam d flowing into the low-carbon emission coal-fired system for flue gas energy utilization flows into the reboiler of the carbon dioxide desorption tower 18, the medium-temperature feed water coming out of the reboiler flows into the reboiler of the concentrated solution regeneration tower 8, the feed water from the reboiler of the concentrated solution regeneration tower 8 flows into the feed water mixer 19, and the feed water c collected in the feed water mixer 19 flows into the feed water heater system.

[0039] The present invention and a specific unit coupling diagram are used as a specific implementation method for explanation, and the connection method is as follows Figure 2 As shown, the unit includes 1-1 for a boiler, 1-2 for a high-pressure cylinder, 1-3 for a medium-pressure cylinder, 1-4 for a heat recovery turbine, 1-5 for a low-pressure cylinder, 1-6 for a condenser, 1-7 for a condensate pump, 1-8 for a deaerator, and 1-9 for a heat recovery heater.

[0040] FGC is a large-scale carbon capture system for flue gas energy utilization of the present invention, and the specific connection method is: the exhaust outlet of the boiler 1-1 is connected to the flue gas port a of FGC, the outlet of the condensate pump 1-7 is connected to the water supply port b of FGC, the outlet of the medium pressure cylinder is connected to the steam port d of FGC, and the water supply port c of FGC is connected to the reheat heater 1-9.

[0041] Figure 2 The boiler exhaust gas in the boiler becomes clean dry air after passing through the water absorption tower and the carbon dioxide absorption tower. Taking the 660MW unit as an example, the coal type parameters used are shown in Table 1.

[0042] Table 1 Composition and content of coal types

[0043]

[0044]

[0045] The contents of various components in the purified flue gas are shown in Table 2.

[0046] Table 2 Flue gas parameters after purification

[0047]

[0048] Compared with the carbon capture system alone, this patent can significantly improve the absorption rate of the carbon capture system, such as Figure 3 shown.

[0049] A control method for a low-carbon emission coal-fired system utilizing flue gas energy, the control method comprising the following steps:

[0050] Step 1: When the unit is running stably, the ratio and flow of the solutions in the flue gas water absorption system and the flue gas carbon dioxide absorption system are adjusted by adjusting the ratio of the inlet flow of the alcohol amine solution mixer 19 and the inlet flow of the solution mixer 20 to obtain the absorption rate of water and carbon dioxide;

[0051] Step 2: When the load of the unit changes, the flow rates of the solution replenishing liquid and the alcohol amine replenishing liquid and the flow rate of the high-temperature and high-pressure steam d are adjusted to meet the absorption rate of water and carbon dioxide. Specifically, when the amount of flue gas a coming out of the boiler increases, the flow rates of the solution replenishing liquid and the alcohol amine replenishing liquid at the inlets of the alcohol amine solution mixer 19 and the solution mixer 20 are increased, and the flow rate of the high-temperature and high-pressure steam d is increased at the same time; when the amount of flue gas a coming out of the boiler decreases, the flow rate of the high-temperature and high-pressure steam d is reduced;

[0052] Step 3: The temperature of the feed water c collected in the feed water mixer 19 is controlled by adjusting the ratio of the feed water from the outlet of the feed water separator 10 entering the lean liquid cooler 15 and the feed water heater 11 .

[0053] By adopting this control method, waste heat can be utilized while satisfying the set absorption amount of carbon dioxide.

Claims

1. A low-carbon emission coal-fired system for flue gas energy utilization, characterized in that: The low-carbon emission coal-fired system for flue gas energy utilization comprises a flue gas water absorption system and a flue gas carbon dioxide absorption system; The flue gas water absorption system comprises an induced draft fan (1), a flue gas cooler (2), a water absorption tower (3), a dilute solution pump (4), a dilute solution separator (5), a concentrated solution mixer (6), a dilute-concentrate solution heat exchanger (7), a concentrated solution regeneration tower (8), a concentrated solution pump (9) and a solution mixer (20), a feed water mixer (19), a feed water heater (11) and a feed water heater (12); The flue gas carbon dioxide absorption system comprises a flue gas cooler (13), a carbon dioxide absorption tower (14), a lean liquid cooler (15), a rich liquid pump (16), a lean and rich liquid heat exchanger (17), a carbon dioxide desorption tower (18) and an alcohol amine solution mixer (19); In the flue gas water absorption system, the flue gas a coming out of the boiler is connected to the inlet of the induced draft fan (1), the outlet of the induced draft fan (1) is connected to the hot end inlet of the flue gas cooler (2), the hot end outlet of the flue gas cooler (2) is connected to the bottom inlet of the water absorption tower (3), the top outlet of the water absorption tower (3) is connected to the hot end inlet of the flue gas cooler (13), the bottom outlet of the water absorption tower (3) is connected to the inlet of the dilute solution pump (4), the outlet of the dilute solution pump (4) is connected to the inlet of the dilute solution separator (5), the two outlets of the dilute solution separator (5) are respectively connected to the inlet of the concentrated solution mixer (6) and the cold end inlet of the dilute-concentrate solution heat exchanger (7), and the dilute-concentrate solution is connected to the inlet of the concentrated solution mixer (6). The cold end outlet of the liquid heat exchanger (7) is connected to the inlet of the concentrated solution regeneration tower (8), the top outlet of the concentrated solution regeneration tower (8) is connected to the hot end inlet of the feed water heater (12), the bottom outlet of the concentrated solution regeneration tower (8) is connected to the inlet of the concentrated solution pump (9), the outlet of the concentrated solution pump (9) is connected to the hot end inlet of the dilute concentrated solution heat exchanger (7), the hot end outlet of the dilute concentrated solution heat exchanger (7) is connected to the hot end inlet of the feed water heater (11) through the concentrated solution mixer (6), the hot end outlet of the feed water heater (11) is connected to the inlet of the solution mixer (20), and the outlet of the solution mixer (20) is connected to the inlet of the water absorption tower (3); In the flue gas carbon dioxide absorption system, the hot end outlet of the flue gas cooler (13) is connected to the bottom inlet of the carbon dioxide absorption tower (14), the bottom outlet of the carbon dioxide absorption tower (14) is connected to the inlet of the rich liquid pump (16), the outlet of the rich liquid pump (16) is connected to the cold end inlet of the lean-rich liquid heat exchanger (17), the cold end outlet of the lean-rich liquid heat exchanger (17) is connected to the inlet of the carbon dioxide desorption tower (18), the top outlet of the carbon dioxide desorption tower (18) discharges carbon dioxide, the bottom outlet of the carbon dioxide desorption tower (18) is connected to the hot end inlet of the lean-rich liquid heat exchanger (17), the hot end outlet of the lean-rich liquid heat exchanger (17) is connected to the hot end inlet of the lean liquid cooler (15), the hot end outlet of the lean liquid cooler (15) is connected to the inlet of the alcohol amine solution mixer (19), and the outlet of the alcohol amine solution mixer (19) is connected to the solvent inlet of the carbon dioxide absorption tower (14).

2. A low-carbon emission coal-fired system for flue gas energy utilization according to claim 1, characterized in that: The flue gas flow in the flue gas carbon capture system for flue gas energy utilization is as follows: the flue gas (a) coming out of the boiler enters the induced draft fan (1) for pressure increase, and then enters the flue gas cooler (2) for cooling; the flue gas coming out of the flue gas cooler (2) enters the water absorption tower (3), moisture in the flue gas is absorbed by the solution in the water absorption tower (3); the flue gas coming out of the top of the water absorption tower (3) is dry flue gas, and the dry flue gas enters the flue gas cooler (13); the flue gas coming out of the flue gas cooler (13) enters the carbon dioxide absorption tower (14), carbon dioxide in the flue gas is absorbed by the alcohol amine solution in the carbon dioxide absorption tower (14), and the flue gas coming out of the top of the carbon dioxide absorption tower (14) is clean flue gas.

3. A low-carbon emission coal-fired system for flue gas energy utilization according to claim 1, characterized in that: The flow of feed water in the flue gas carbon capture system for flue gas energy utilization is as follows: the feed water (b) from the condenser outlet flows into the flue gas cooler (13) for heating, the feed water flowing out of the flue gas cooler (13) flows into the feed water separator (10), part of the feed water flowing out of the feed water separator (10) enters the lean liquid cooler (15), and the other part flows into the feed water heater (11), the feed water entering the lean liquid cooler (15) enters the flue gas cooler (2), and finally flows into the feed water mixer (19), while the feed water flowing into the feed water heater (11) flows into the feed water heater (12), then flows into the condenser of the carbon dioxide desorption tower (18), and finally flows into the feed water mixer (19), and the feed water (c) collected in the feed water mixer (19) flows into the feed water heater system.

4. A low-carbon emission coal-fired system for flue gas energy utilization according to claim 1, characterized in that: The solution adopted by the flue gas water absorption system is a calcium chloride solution; the solution adopted by the flue gas carbon dioxide absorption system is an alcohol amine solution.

5. A low-carbon emission coal-fired system for flue gas energy utilization according to claim 1, characterized in that: The high-temperature and high-pressure steam (d) flowing into the low-carbon emission coal-fired system for flue gas energy utilization flows into the reboiler of the carbon dioxide desorption tower (18), the medium-temperature feed water coming out of the reboiler flows into the reboiler of the concentrated solution regeneration tower (8), the feed water from the reboiler of the concentrated solution regeneration tower (8) flows into the feed water mixer (19), and the feed water (c) collected in the feed water mixer (19) flows into the feed water heater system.

6. A low-carbon emission coal-fired system for flue gas energy utilization according to claim 1, characterized in that: The pressure range of the flue gas at the outlet of the induced draft fan (1) is 140-150 kPa, and the operating pressure of the water absorption tower (3) is lower than the pressure of the flue gas at the outlet of the induced draft fan (1).

7. A low-carbon emission coal-fired system for flue gas energy utilization according to claim 1, characterized in that: The pressure range of the concentrated solution regeneration tower (8) is 30-40 kPa, and the outlet pressure range of the concentrated solution pump (9) is 200-250 kPa.

8. A low-carbon emission coal-fired system for flue gas energy utilization according to claim 1, characterized in that: The pressure range of the carbon dioxide absorption tower (14) is 100-120 kPa, and the pressure range of the rich liquid at the outlet of the rich liquid pump (16) is 170-220 kPa.

9. A low-carbon emission coal-fired system for flue gas energy utilization according to claim 1, characterized in that: The operating pressure range of the carbon dioxide desorption tower (18) is 160-200 kPa, and is less than the outlet pressure of the rich liquid pump (16).

10. A control method for a low-carbon emission coal-fired system utilizing flue gas energy according to any one of claims 1 to 9, characterized in that: The following steps are involved: Step 1: When the unit is running stably, the ratio and flow of the solutions in the flue gas water absorption system and the flue gas carbon dioxide absorption system are adjusted by adjusting the ratio of the inlet flow rates of the alcohol amine solution mixer (19) and the solution mixer (20) to obtain the absorption rates of water and carbon dioxide; Step 2: When the load of the unit changes, the flow rates of the solution replenishing liquid and the alcohol amine replenishing liquid and the flow rate of the high-temperature and high-pressure steam (d) are adjusted to meet the absorption rate of water and carbon dioxide. Specifically, when the amount of flue gas (a) coming out of the boiler increases, the flow rates of the solution replenishing liquid and the alcohol amine replenishing liquid at the inlets of the alcohol amine solution mixer (19) and the solution mixer (20) are increased, and the flow rate of the high-temperature and high-pressure steam (d) is increased; when the amount of flue gas (a) coming out of the boiler decreases, the flow rate of the high-temperature and high-pressure steam (d) is reduced; Step 3: By adjusting the ratio of the feed water from the outlet of the feed water separator (10) entering the lean liquid cooler (15) and the feed water heater (11), the temperature of the feed water (c) collected in the feed water mixer (19) is controlled.

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