CN116712836A - An energy-saving method coupled with CCS and low-temperature waste heat recovery - Google Patents

Abstract

A CCS and low-temperature waste heat recovery coupling energy-saving method belongs to the technical field of carbon dioxide capture. Solves the problems of large energy consumption and high cost of the existing carbon dioxide capturing technology. The technical key points are as follows: the low-temperature waste heat recovery system transfers heat absorbed by low-temperature flue gas to a heat transfer medium, the heat transfer medium is heated by a heater again and then enters a reboiler for heat exchange, and the heat transfer medium subjected to heat exchange enters the low-temperature waste heat recovery system again for heat absorption; according to the application, the purpose of carbon dioxide trapping is realized by a mode that the low-temperature waste heat recovery system recovers the heat of the flue gas, the carbon dioxide is trapped by the absorption tower, the carbon dioxide is desorbed by the regeneration tower and the heat of the lean solution is transferred to the rich solution by the absorbent heat exchanger, so that the heat in the low-temperature flue gas is fully recovered for production, the temperature of the flue gas is reduced, the carbon dioxide trapping and absorbing efficiency is improved, and the energy consumption of carbon dioxide trapping is reduced. The application has the advantages of stability, reliability, deep utilization of waste heat in the flue gas, energy conservation and great economic benefit.

Description

An energy-saving method coupled with CCS and low-temperature waste heat recovery

Technical field

The invention relates to an energy-saving system and an energy-saving method, specifically an energy-saving method coupling CCS and low-temperature waste heat recovery, and belongs to the technical field of carbon dioxide capture.

Background technique

Carbon dioxide capture and storage technology (CCS) is a new technology with large-scale carbon dioxide emission reduction potential. It is the only technology option for fossil energy to achieve net-zero emissions. The CCS industry will enter a rapid growth track. At present, CCS systems have problems such as complex process flows, high initial investment costs, and large operating energy consumption. The development of high-efficiency and low-energy CCS technology is the key to gaining large-scale applications and markets. Post-combustion carbon dioxide capture technology is the most suitable commercial technology for capturing carbon dioxide. At present, carbon dioxide capture technology has the characteristics of high energy consumption and high cost, which seriously limits its large-scale application.

Contents of the invention

In view of the above facts, in order to solve the problems of high energy consumption and high cost in the existing carbon dioxide capture technology, the present invention further designs an energy-saving method coupling CCS and low-temperature waste heat recovery to recover flue gas heat through the low-temperature waste heat recovery system+ The absorption tower captures carbon dioxide + the regeneration tower desorbs carbon dioxide + the absorbent heat exchanger transfers the heat of the lean liquid to the rich liquid to achieve the purpose of carbon dioxide capture, and fully recovers the heat in the low-temperature flue gas for production, reducing the flue gas temperature It improves the carbon dioxide capture and absorption efficiency and reduces the energy consumption of carbon dioxide capture; truly achieving the goals of carbon peaking, carbon neutrality and energy saving.

In order to achieve the above objects, the present invention adopts the following technical solutions:

An energy-saving method for coupling CCS and low-temperature waste heat recovery. The method is realized by coupling an energy-saving system for CCS and low-temperature waste heat recovery. The energy-saving system includes a low-temperature waste heat recovery system, a carbon dioxide absorption tower, a regeneration tower, an absorbent heat exchanger, and a heating system. device, gas-liquid separator and reboiler;

The low-temperature waste heat recovery system is connected to the low-temperature flue gas inlet pipeline and connected to the lower part of the carbon dioxide absorption tower through the low-temperature flue gas outlet pipeline;

In the carbon dioxide absorption tower, low-temperature flue gas flows upward, and the absorbent flows downward. The top surface of the carbon dioxide absorption tower is connected with a clean flue gas outlet pipeline. The carbon dioxide absorption tower is connected to the absorbent heat exchanger through the first absorbent circulation pipeline. , a second cooler is provided on the first absorbent circulation pipeline;

The absorbent heat exchanger is connected to the regeneration tower through a second adsorbent circulation pipeline;

The gas-liquid separator is connected to the regeneration tower through a third adsorbent circulation pipeline, and a first cooler is provided on the third adsorbent circulation pipeline;

The reboiler is connected to the low-temperature waste heat recovery system through a heat transfer medium circulation pipeline. A heater is provided on the heat transfer medium circulation pipeline. The heat transfer medium enters the reboiler after being heated by the heater;

specific method:

After the low-temperature flue gas after combustion has undergone dust removal and desulfurization processes, the low-temperature flue gas then enters the low-temperature waste heat recovery system for waste heat recovery, and then enters the carbon dioxide absorption tower. The clean flue gas after carbon dioxide removal is discharged from the top of the carbon dioxide absorption tower;

The low-temperature flue gas and absorbent are in reverse contact in the carbon dioxide absorption tower. The absorbent after absorbing carbon dioxide is extracted from the bottom of the carbon dioxide absorption tower, and then enters the absorbent heat exchanger, where it is combined with the regenerated absorbent extracted from the bottom of the regeneration tower. The absorbent after heat exchange enters the regeneration tower from the top of the regeneration tower for regeneration. The absorbent flows from the top to the bottom of the regeneration tower. After reaching the bottom of the tower, it turns into a lean liquid absorbent and is extracted from the bottom of the regeneration tower. After the heat is transferred to the absorbent in the agent heat exchanger, it is cooled by the second cooler and enters the carbon dioxide absorption tower to absorb carbon dioxide again;

The mixed gas of carbon dioxide and absorbent is discharged from the top of the regeneration tower. After being cooled by the first cooler, the gas and liquid are separated to separate pure carbon dioxide as the product of the system. The remaining liquid component is the absorbent and flows back to the regeneration tower for regeneration;

The low-temperature waste heat recovery system is driven by steam and transfers the heat absorbed from the low-temperature flue gas to the heat transfer medium. After the heat transfer medium is heated by the heater again, it enters the reboiler for heat exchange. The heat transfer medium after heat exchange is again Enter the low-temperature waste heat recovery system to absorb heat.

Further: the low-temperature waste heat recovery system is driven by steam.

Further: the bottom surface of the carbon dioxide absorption tower is connected to one end of the first absorbent circulation pipeline, and the upper side wall of the carbon dioxide absorption tower is connected to the other end of the first absorbent circulation pipeline. The first absorbent circulation pipeline is in accordance with An absorbent heat exchanger and a second cooler are provided in the flow direction of the adsorbent.

Further: one end of the second adsorbent circulation pipeline is connected to the bottom surface of the regeneration tower, and the other end of the second adsorbent circulation pipeline is connected to the upper side wall of the regeneration tower.

Further: one end of the third adsorbent circulation pipeline is connected to the top surface of the regeneration tower, the other end of the third adsorbent circulation pipeline is connected to the upper side wall of the regeneration tower, and the third adsorbent circulation pipeline is provided with There is a first cooler, and the adsorbent enters the gas-liquid separator after cooling.

Further: the reboiler is connected to the lower side wall of the regeneration tower through a fourth adsorbent circulation pipeline.

The effects achieved by the present invention are:

The present invention is an energy-saving method coupled with CCS and low-temperature waste heat recovery, which uses a low-temperature waste heat recovery system to recover flue gas heat + an absorption tower to capture carbon dioxide + a regeneration tower to desorb carbon dioxide + an absorbent heat exchanger to transfer heat from lean liquid to rich liquid , achieve the purpose of carbon dioxide capture, and fully recover the heat in low-temperature flue gas for production. Lowering the flue gas temperature improves the carbon dioxide capture and absorption efficiency and reduces the energy consumption of carbon dioxide capture; truly achieving carbon peak and carbon neutrality. and energy saving purposes. The invention has the advantages of stability and reliability, deep utilization of waste heat in flue gas, energy saving, large economic benefits and reduction of carbon dioxide emissions.

Description of the drawings

Figure 1 is a schematic diagram of an energy-saving system coupled with CCS and low-temperature waste heat recovery according to the present invention.

In the picture: 1-low temperature waste heat recovery system; 2-carbon dioxide absorption tower; 3-regeneration tower; 4-absorbent heat exchanger; 5-heater; 6-first cooler; 7-gas-liquid separator; 8- Reboiler; 9-Second cooler.

Detailed ways

In order to enable those in the technical field to better understand the solutions of the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only These are part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative efforts should fall within the scope of protection of this application.

The terms "setting", "connection" and "fixing" are to be understood broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral structure; it can be a mechanical connection, or an electrical connection; it can be a direct connection, or an indirect connection through an intermediary, or two devices, components or Internal connections between components. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances.

It should be noted that, as long as there is no conflict, the embodiments and features in the embodiments of this application can be combined with each other. The present application will be described in detail below with reference to Figure 1 and embodiments.

Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

Embodiment: Referring to Figure 1, an energy-saving method of coupling CCS and low-temperature waste heat recovery in this embodiment is specifically as follows:

After combustion, the low-temperature flue gas FG undergoes dust removal and desulfurization processes. The low-temperature flue gas FG then enters the low-temperature waste heat recovery system 1 for waste heat recovery, and then enters the carbon dioxide absorption tower 2. The clean flue gas VE after removing carbon dioxide passes from the carbon dioxide absorption tower 2 Top discharge;

Low-temperature flue gas FG and absorbent AB are in reverse contact in the carbon dioxide absorption tower 2. The absorbent AB (i.e. rich liquid) after absorbing carbon dioxide is extracted from the bottom of the carbon dioxide absorption tower 2, and then enters the absorbent heat exchanger 4. It exchanges heat with the regenerated absorbent AB (i.e., lean liquid) extracted from the bottom of the regeneration tower 3. The heat-exchanged absorbent AB enters the regeneration tower 3 from the top of the regeneration tower 3 for regeneration, and the absorbent AB flows from the top of the regeneration tower to the bottom. After reaching the bottom of the tower, it becomes lean absorbent AB and is extracted from the bottom of the regeneration tower. After transferring heat to the absorbent AB in the absorbent heat exchanger 4, it is cooled by the second cooler 9 and enters the carbon dioxide absorption tower. 2. Absorb carbon dioxide again;

The mixed gas of carbon dioxide and absorbent AB is discharged from the top of the regeneration tower 3. After being cooled by the first cooler 6, gas-liquid separation is performed to separate pure carbon dioxide as the product of the system. The remaining liquid component is the absorbent AB and flows back to regeneration. The tower undergoes regeneration;

The low-temperature waste heat recovery system is driven by steam ST and transfers the heat absorbed from the low-temperature flue gas FG to the heat transfer medium ME. After being heated by the heater 5 again, the heat transfer medium ME enters the reboiler 8 for heat exchange. The hot heat transfer medium ME enters the low-temperature waste heat recovery system 1 again to absorb heat.

The energy-saving system implemented by the above energy-saving method includes low-temperature waste heat recovery system 1, carbon dioxide absorption tower 2, regeneration tower 3, absorbent heat exchanger 4, heater 5, gas-liquid separator 7 and reboiler 8;

The low-temperature waste heat recovery system 1 is connected to the low-temperature flue gas inlet pipeline, and is connected to the lower part of the carbon dioxide absorption tower 2 through the low-temperature flue gas outlet pipeline; the low-temperature waste heat recovery system 1 is driven by steam. The condensed water W flows out through the condensed water outlet pipe;

In the carbon dioxide absorption tower 2, the low-temperature flue gas goes up and the absorbent goes down. The top surface of the carbon dioxide absorption tower 2 is connected with a clean flue gas outlet pipeline. The carbon dioxide absorption tower 2 exchanges heat with the absorbent through the first absorbent circulation pipeline. The bottom surface of the carbon dioxide absorption tower 2 is connected to one end of the first absorbent circulation pipeline, the upper side wall of the carbon dioxide absorption tower 2 is connected to the other end of the first absorbent circulation pipeline, and the first absorbent An absorbent heat exchanger 4 and a second cooler 9 are provided on the circulation pipeline according to the flow direction of the adsorbent;

The absorbent heat exchanger 4 is connected to the regeneration tower 3 through a second adsorbent circulation pipeline; one end of the second adsorbent circulation pipeline is connected to the bottom surface of the regeneration tower 3, and the second adsorbent circulation pipeline is connected to the bottom surface of the regeneration tower 3. The other end is connected to the upper side wall of the regeneration tower 3;

The gas-liquid separator 7 is connected to the regeneration tower 3 through a third adsorbent circulation pipeline; one end of the third adsorbent circulation pipeline is connected to the top surface of the regeneration tower 3, and the other end of the third adsorbent circulation pipeline is connected to the top surface of the regeneration tower 3. One end is connected to the upper side wall of the regeneration tower 3, and a first cooler 6 is provided on the third adsorbent circulation pipeline. After the adsorbent is cooled, it enters the gas-liquid separator 7;

The reboiler 8 is connected to the low-temperature waste heat recovery system 1 through a heat transfer medium circulation pipeline. A heater 5 is provided on the heat transfer medium circulation pipeline. The heat transfer medium enters the reboiler 8 after being heated by the heater 5; The reboiler 8 is connected to the lower side wall of the regeneration tower 3 through the fourth adsorbent circulation pipeline.

By adopting the energy-saving method of this embodiment, the flue gas temperature can be reduced, the carbon dioxide capture and absorption efficiency can be improved, and the energy consumption of the carbon dioxide capture system can be reduced, thereby truly achieving the goals of carbon peaking, carbon neutrality, and energy saving. This system has the characteristics and advantages of being stable and reliable, deeply utilizing the waste heat in the flue gas, saving energy, having great economic benefits, and reducing carbon dioxide emissions.

The above embodiments are only used to illustrate the technical solutions of the present invention, but not to limit them. Although the present invention has been described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that they can still modify the foregoing embodiments. The recorded technical solutions may be modified, or some or all of the technical features may be equivalently replaced; and these modifications or substitutions shall not cause the essence of the corresponding technical solutions to depart from the scope of the technical solutions of the embodiments of the present invention.

In addition, it should be understood that although this specification is described in terms of implementations, not each implementation only contains an independent technical solution. This description of the specification is only for the sake of clarity, and those skilled in the art should take the specification as a whole. , the technical solutions in each embodiment can also be appropriately combined to form other implementations that can be understood by those skilled in the art.

Claims (6)

1. A CCS and low-temperature waste heat recovery coupling energy-saving method is characterized in that: the method is realized by means of a CCS and low-temperature waste heat recovery coupling energy-saving system, wherein the energy-saving system comprises a low-temperature waste heat recovery system (1), a carbon dioxide absorption tower (2), a regeneration tower (3), an absorbent heat exchanger (4), a heater (5), a gas-liquid separator (7) and a reboiler (8);

the low-temperature waste heat recovery system (1) is connected with a low-temperature flue gas inlet pipeline and is connected to the lower part of the carbon dioxide absorption tower (2) through a low-temperature flue gas outlet pipeline;

the low-temperature flue gas in the carbon dioxide absorption tower (2) goes upward, the absorbent goes downward, a clean flue gas outlet pipeline is connected to the top surface of the carbon dioxide absorption tower (2), the carbon dioxide absorption tower (2) is connected with the absorbent heat exchanger (4) through a first absorbent circulating pipeline, and a second cooler (9) is arranged on the first absorbent circulating pipeline;

the absorbent heat exchanger (4) is connected with the regeneration tower (3) through a second absorbent circulating pipeline;

the gas-liquid separator (7) is connected with the regeneration tower (3) through a third adsorbent circulation pipeline, and a first cooler (6) is arranged on the third adsorbent circulation pipeline;

the reboiler (8) is connected with the low-temperature waste heat recovery system (1) through a heat transfer medium circulation pipeline, a heater (5) is arranged on the heat transfer medium circulation pipeline, and the heat transfer medium enters the reboiler (8) after being heated by the heater (5);

the specific method comprises the following steps:

after the low-temperature flue gas after combustion passes through a dust removal and desulfurization process, the low-temperature flue gas enters a low-temperature waste heat recovery system (1) for waste heat recovery, then enters a carbon dioxide absorption tower (2), and the purified flue gas subjected to carbon dioxide removal is discharged from the top of the carbon dioxide absorption tower (2);

the low-temperature flue gas and the absorbent are reversely contacted in the carbon dioxide absorption tower (2), the absorbent after absorbing carbon dioxide is extracted from the bottom of the carbon dioxide absorption tower (2) and then enters an absorbent heat exchanger (4), heat exchange is carried out between the absorbent and the regenerated absorbent extracted from the bottom of the regeneration tower (3), the absorbent after heat exchange enters the regeneration tower (3) from the top of the regeneration tower (3) for regeneration, the absorbent flows from the top of the regeneration tower to the bottom, becomes lean absorbent after reaching the bottom of the tower, is extracted from the bottom of the regeneration tower, transfers heat to the absorbent in the absorbent heat exchanger (4), is cooled by a second cooler (9), and enters the carbon dioxide absorption tower (2) for re-absorption of carbon dioxide;

the mixed gas of the carbon dioxide and the absorbent is discharged from the top of the regeneration tower (3), is cooled by a first cooler (6), is subjected to gas-liquid separation, pure carbon dioxide is separated out as a product of the system, and the rest liquid component is the absorbent and flows back to the regeneration tower for regeneration;

the low-temperature waste heat recovery system is driven by steam, heat absorbed by low-temperature flue gas is transferred to a heat transfer medium, the heat transfer medium is heated by a heater (5) again and then enters a reboiler (8) for heat exchange, and the heat transfer medium subjected to heat exchange enters the low-temperature waste heat recovery system (1) again for heat absorption.

2. The CCS and low temperature waste heat recovery coupled energy saving method as defined in claim 1, wherein: the low-temperature waste heat recovery system (1) is driven by steam.

3. The CCS and low temperature waste heat recovery coupled energy saving method as defined in claim 2, wherein: the bottom surface of carbon dioxide absorption tower (2) is connected with one end of first absorbent circulation pipeline, and the upper portion lateral wall of carbon dioxide absorption tower (2) is connected with the other end of first absorbent circulation pipeline, is provided with absorbent heat exchanger (4), second cooler (9) according to the flow direction of adsorbent on the first absorbent circulation pipeline.

4. The CCS and low temperature waste heat recovery coupled energy saving method as defined in claim 3, wherein: one end of the second adsorbent circulation pipeline is connected to the bottom surface of the regeneration tower (3), and the other end of the second adsorbent circulation pipeline is connected to the upper side wall of the regeneration tower (3).

5. The CCS and low temperature waste heat recovery coupled energy saving method as defined in claim 4, wherein: one end of the third adsorbent circulation pipeline is connected to the top surface of the regeneration tower (3), the other end of the third adsorbent circulation pipeline is connected to the upper side wall of the regeneration tower (3), a first cooler (6) is arranged on the third adsorbent circulation pipeline, and the adsorbent enters the gas-liquid separator (7) after being cooled.

6. The CCS and low temperature waste heat recovery coupled energy saving method as defined in claim 5, wherein: the reboiler (8) is connected with the lower side wall of the regeneration tower (3) through a fourth adsorbent circulation pipeline.