阅读说明：本技术 基于水合物法的水泥窑烟气二氧化碳捕集储存系统 (Cement kiln flue gas carbon dioxide capture and storage system based on hydrate method ) 是由 刘仁越 赵美江 张健 吴梦欣 朱刚 汤升亮 宿向超 宋华庭 姜凯 冯冬梅 朱永长 于 2021-07-23 设计创作，主要内容包括：本发明公开了一种基于水合物法的水泥窑烟气二氧化碳捕集储存系统,包括依次连接的废气预处置单元和进气增压制冷单元,进气增压制冷单元的出口连接水合反应罐一级室的入口进行一级水合反应,水合反应罐一级室的出口连接水合分解罐一级室的入口进行一级分离,水合分解罐一级室的出口连接水合反应罐二级室的入口进行二级水合反应,水合反应罐二级室的出口连接水合分解罐二级室的入口进行二级分离,水合分解罐二级室的出口连接CO-(2)冷却回收单元；分别向水合反应罐一级室、水合反应罐二级室供液用于水合反应的供液单元。通过两级水合反应和两级水合分解实现对CO-(2)的连续离释,得到浓度高达99％的CO-(2)气体,并通过冷却、干燥和压缩进行存储。(The invention discloses a cement kiln flue gas carbon dioxide capturing and storing system based on a hydrate method, which comprises a waste gas pretreatment unit and an air inlet pressurizing and refrigerating unit which are sequentially connected, wherein an outlet of the air inlet pressurizing and refrigerating unit is connected with an inlet of a first-stage chamber of a hydration reaction tank to perform first-stage hydration reaction, an outlet of the first-stage chamber of the hydration reaction tank is connected with an inlet of a first-stage chamber of a hydration decomposition tank to perform first-stage separation, an outlet of the first-stage chamber of the hydration decomposition tank is connected with an inlet of a second-stage chamber of the hydration reaction tank to perform second-stage hydration reaction, an outlet of the second-stage chamber of the hydration reaction tank is connected with an inlet of the second-stage chamber of the hydration decomposition tank to perform second-stage separation, and an outlet of the second-stage chamber of the hydration decomposition tank is connected with CO 2 A cooling recovery unit; and the liquid supply unit is used for supplying liquid to the first-stage chamber of the hydration reaction tank and the second-stage chamber of the hydration reaction tank respectively for hydration reaction. CO separation by two-stage hydration reaction and two-stage hydration decomposition 2 To obtain CO with a concentration of up to 99% 2 Gas and stored by cooling, drying and compression.)

1. The utility model provides a cement kiln flue gas carbon dioxide entrapment storage system based on hydrate method, includes the waste gas preliminary treatment unit that connects gradually and admits air pressure boost refrigerating unit, its characterized in that, the entry of the exit linkage hydration retort first order room (20A) of pressure boost refrigerating unit admits air carries out one-level hydration reaction, the entry of the exit linkage hydration decomposition tank first order room (23A) of hydration retort first order room (20A) carries out one-level separation, the exit linkage hydration of hydration decomposition tank first order room (23A) is anti-to-hydrateThe inlet of the second-stage chamber (20B) of the reactor is used for carrying out second-stage hydration reaction, the outlet of the second-stage chamber (20B) of the hydration reactor is connected with the inlet of the second-stage chamber (23B) of the hydration decomposition tank for carrying out second-stage separation, and the outlet of the second-stage chamber (23B) of the hydration decomposition tank is connected with CO₂A cooling recovery unit; the device also comprises a liquid supply unit which supplies liquid to the first-stage chamber (20A) of the hydration reaction tank and the second-stage chamber (20B) of the hydration reaction tank respectively for hydration reaction.

2. The system for capturing and storing the carbon dioxide in the flue gas of the cement kiln based on the hydrate method according to the claim 1, wherein the tops of the primary chamber (20A) of the hydration reaction tank and the secondary chamber (20B) of the hydration reaction tank are respectively provided with an atomizing and spraying device which is connected with a liquid supply unit and is used for the nucleation reaction of the hydrate; the device also comprises a quenching water device which is used for dissipating heat generated in the atomization spraying process and participating in hydration reaction.

3. The hydrate method-based cement kiln flue gas carbon dioxide capture and storage system according to claim 2, wherein the quenching water device comprises quenching water nozzles respectively arranged in the hydration reaction tank primary chamber (20A) and the hydration reaction tank secondary chamber (20B), and a quenching water storage tank for supplying water to the quenching water nozzles through a water pipe.

4. The system for capturing and storing the carbon dioxide in the flue gas of the cement kiln based on the hydrate method according to the claim 1, wherein the top of the primary chamber (20A) of the hydration reaction tank and the top of the secondary chamber (20B) of the hydration reaction tank are respectively provided with a solution inlet for inputting the aqueous solution containing the hydrate promoter and a separated gas outlet for discharging the separated gas after the hydration reaction; the bottoms of the first-stage chamber (20A) of the hydration reaction tank and the second-stage chamber (20B) of the hydration reaction tank are respectively provided with a flue gas inlet and a hydrate outlet.

5. The system for capturing and storing the carbon dioxide in the flue gas of the cement kiln based on the hydrate method as claimed in claim 1, wherein the first-stage chamber (23A) and the second-stage chamber (23B) of the hydration decomposition tank are arranged in the hydration decomposition tank in a longitudinal manner, the bottom of the hydration decomposition tank is connected with a low-temperature waste heat storage tank (27) for supplying heat to the first-stage chamber (23A) and the second-stage chamber (23B) of the hydration decomposition tank, and the low-temperature waste heat storage tank (27) recovers the waste heat of the grate cooler, the rotary kiln and the decomposition furnace of the cement kiln.

6. The hydrate method based cement kiln flue gas carbon dioxide capture and storage system according to claim 1, characterized in that a hydrate inlet at the bottom of the primary chamber (23A) of the hydration decomposition tank is connected with a flue gas outlet at the bottom of the primary chamber (20A) of the hydration reaction tank, and a decomposition gas outlet at the top of the primary chamber (23A) of the hydration decomposition tank is connected with a flue gas inlet at the bottom of the secondary chamber (20B) of the hydration reaction tank through a third heat exchanger (24), a second gas compressor (25) and a second gas refrigerator (26); a hydrate inlet at the bottom of the secondary chamber (23B) of the hydration decomposition tank is connected with a smoke outlet at the bottom of the secondary chamber (20B) of the hydration reaction tank; a decomposed gas outlet and CO at the top of the secondary chamber (23B) of the hydration decomposition tank₂Cooling CO of recovery unit₂The inlet of the drying device is connected.

7. The hydrate method based cement kiln flue gas carbon dioxide capture and storage system according to claim 1, wherein the top of the first-stage chamber (23A) of the hydration decomposition tank and the top of the second-stage chamber (23B) of the hydration decomposition tank are respectively provided with a separation liquid outlet, the two separation liquid outlets share a pipeline, the pipeline is provided with a heat exchange device and is connected with the solution storage tank (10) of the liquid supply unit through a check valve and a second liquid booster pump.

8. The system for capturing and storing the carbon dioxide in the flue gas of the cement kiln based on the hydrate method as claimed in claim 1, wherein a water replenishing pipe (8) and a hydrate accelerant replenishing pipe (9) are arranged at the upper part of the solution storage tank (10), the solution storage tank (10) is provided with a liquid outlet and a separation liquid inlet, the liquid outlet of the solution storage tank (10) is sequentially connected with the second heat exchanger (11), the first liquid regulating valve (12) and the first liquid booster pump (13) and then divided into two pipelines, and one pipeline is connected with the solution inlet at the upper part of the primary chamber (20A) of the hydration reaction tank through the first back pressure valve (33); one path is connected with a solution inlet at the upper part of a secondary chamber (20B) of the hydration reaction tank through a second backpressure valve (34).

9. The system for capturing and storing the carbon dioxide in the flue gas of the cement kiln based on the hydrate method according to claim 1, wherein the hydration reaction tank primary chamber (20A) and the hydration reaction tank secondary chamber (20B) are separated by two layers of pressure-resistant steel plates, and heat-insulating cooling materials are filled in the steel plates to keep the temperature in the tank constant.

10. The hydrate method-based cement kiln flue gas carbon dioxide capture and storage system according to claim 1, wherein the exhaust gas pretreatment unit comprises an electrostatic precipitator (3) and a first heat exchanger (4) which are connected in sequence.

Technical Field

The invention relates to a carbon capture system in the cement industry, in particular to a capture and storage system for carbon dioxide in flue gas of a cement kiln based on a hydrate method.

Background

The production of cement is a high energy consumption process, the energy consumption accounts for about 2% of the global primary energy consumption, and the production process mainly utilizes carbon-intensive fuels such as coal and the like, so that the cement industry becomes a huge carbon dioxide emission source. In addition to energy consumption processes, the calcination process of cement clinker also produces large amounts of carbon dioxide.

The carbon capture and sequestration technology (CCS) is one of the core strategies of the carbon dioxide comprehensive treatment scheme, and has the advantages of effectively realizing carbon emission reduction, generating economic benefit, not needing to modify a production system in a large scale and reducing the capture cost. The CCS technology consists of two parts, carbon capture and carbon sequestration. Among them, the carbon capture technology is mainly divided into three categories,namely pre-combustion capture, oxy-fuel combustion technology and post-combustion capture. The pre-combustion capture is a method in which a fuel is first gasified to generate a synthesis gas, and then further reacted to generate hydrogen and high-concentration carbon dioxide, and finally carbon capture is performed. This trapping technology is only applied to the process of fuel combustion, and cannot trap carbon dioxide generated during the calcination of the raw material, and is therefore not suitable for use in the cement industry. The oxycombustion technology utilizes pure oxygen to replace air to participate in the combustion process, so as to generate high-concentration carbon dioxide for further capture and storage. The oxygen-enriched combustion technology has the disadvantages of higher reaction temperature, large energy consumption and relatively higher requirement on investment. The post-combustion capture refers to capture and separation of CO from flue gas discharged from a production system₂The technology is suitable for low-concentration CO₂The capture of the cement is wide in application range, and the reconstruction of a combustion process and the existing facilities is omitted for the existing cement plant. The post-combustion capture technology is implemented in many ways, and is mainly classified into a chemical absorption method, a physical adsorption method, a membrane separation method, a cryogenic distillation method, and the like, and currently, the most widely used CO is₂The trapping method is an alcohol amine absorption method. The alcohol amine method can trap 85-95% of CO₂Absorb CO₂The solvent is then heated and desorbed to obtain high-concentration CO₂And (5) transporting and sealing the gas. However, the chemical absorption method has complex process, large investment, toxic solvent, large energy consumption for solvent regeneration and high trapping cost, and can not realize considerable economic benefit.

Hydrate method for separating CO₂In recent years, a wide range of attention has been paid. Hydrates are non-stoichiometric compounds of crystalline structure, gas molecules of different molecular weights, e.g. CO₂、N₂、H₂Under certain temperature and pressure, the crystal and water molecules crystallize through hydrogen bond to form cage crystal of different structure, and the water molecules in the crystal structure are combined through hydrogen bond and the gas molecules and the water molecules are combined through Van der Waals force. The principle of hydrate separation is that different gas molecules are utilized to generate different required pressures and temperatures of hydrates, and the gas which is easy to generate the hydrates is enriched in the hydrate phase by controlling the temperature and the pressure in the growth process of the hydrates, so that the further separation is achievedThe purpose of the separation is. Hydrate method for separating CO₂Low energy consumption, simple operation and trapping cost of about 50 percent of the chemical absorption method, and is considered to be the long-term CO with the most development potential₂A trapping technique.

At present, whether the process for separating gas by using the hydrate method can be industrialized or not is limited by the nucleation speed of the gas hydrate and the gas separation efficiency, and particularly, the nucleation speed of the gas hydrate is limited by the CO capture by using the hydrate method₂Key factors of the technology. At present, a hydrate method obtains certain achievements in the field of carbon capture, but has certain problems, such as incapability of continuous operation in large-flow flue gas, slow nucleation of hydrates, incapability of timely dissipation of generated heat and accumulation of generated heat in liquid drops and the like. Based on the defects, a hydrate method equipment system which is efficient and environment-friendly and can fully utilize waste heat of the cement industry is urgently needed to be developed so as to realize the carbon emission reduction vision of the cement industry.

Disclosure of Invention

The purpose of the invention is as follows: the invention aims to provide a hydrate method-based cement kiln flue gas carbon dioxide capturing and storing system which is low in cost, free of pollution and good in capturing effect.

The technical scheme is as follows: the cement kiln flue gas carbon dioxide capturing and storing system based on the hydrate method comprises a waste gas pretreatment unit and an air inlet pressurizing and refrigerating unit which are sequentially connected, wherein an outlet of the air inlet pressurizing and refrigerating unit is connected with an inlet of a first-stage chamber of a hydration reaction tank to perform first-stage hydration reaction, an outlet of the first-stage chamber of the hydration reaction tank is connected with an inlet of a first-stage chamber of a hydration decomposition tank to perform first-stage separation, an outlet of the first-stage chamber of the hydration decomposition tank is connected with an inlet of a second-stage chamber of the hydration reaction tank to perform second-stage hydration reaction, an outlet of the second-stage chamber of the hydration reaction tank is connected with an inlet of the second-stage chamber of the hydration decomposition tank to perform second-stage separation, and an outlet of the second-stage chamber of the hydration decomposition tank is connected with CO₂A cooling recovery unit; the device also comprises a liquid supply unit which supplies liquid to the first-stage chamber of the hydration reaction tank and the second-stage chamber of the hydration reaction tank respectively for hydration reaction.

Preferably, the tops of the first-stage chamber and the second-stage chamber of the hydration reaction tank are respectively provided with an atomization spraying device which is connected with the liquid supply unit and is used for the nucleation reaction of the hydrate; the device also comprises a quenching water device which is used for dissipating heat generated in the atomization spraying process and participating in hydration reaction.

Preferably, the quenching water device comprises a quenching water nozzle respectively arranged in the first-stage chamber and the second-stage chamber of the hydration reaction tank, and a quenching water storage tank for supplying water to the quenching water nozzle through a water pipe.

Preferably, the top of the first-stage chamber of the hydration reaction tank and the top of the second-stage chamber of the hydration reaction tank are respectively provided with a solution inlet for inputting aqueous solution containing hydrate accelerant and a separated gas outlet for discharging separated gas after hydration reaction; and the bottoms of the first-stage chamber of the hydration reaction tank and the second-stage chamber of the hydration reaction tank are respectively provided with a flue gas inlet and a hydrate outlet.

Preferably, the primary chamber of the hydration decomposition tank and the secondary chamber of the hydration decomposition tank are longitudinally arranged in the hydration decomposition tank, the bottom of the hydration decomposition tank is connected with a low-temperature waste heat storage tank for supplying heat to the primary chamber of the hydration decomposition tank and the secondary chamber of the hydration decomposition tank, and the low-temperature waste heat storage tank recovers the waste heat of the cement kiln grate cooler, the rotary kiln and the decomposition furnace.

Preferably, a hydrate inlet at the bottom of the primary chamber of the hydration decomposition tank is connected with a flue gas outlet at the bottom of the primary chamber of the hydration reaction tank, and a decomposed gas outlet at the top of the primary chamber of the hydration decomposition tank is connected with a flue gas inlet at the bottom of the secondary chamber of the hydration reaction tank through a third heat exchanger, a second gas compressor and a second gas refrigerator; a hydrate inlet at the bottom of the secondary chamber of the hydration decomposition tank is connected with a flue gas outlet at the bottom of the secondary chamber of the hydration reaction tank; a decomposed gas outlet and CO at the top of the secondary chamber of the hydration decomposition tank₂Cooling CO of recovery unit₂The inlet of the drying device is connected.

Preferably, the top of the first-stage chamber of the hydration decomposition tank and the top of the second-stage chamber of the hydration decomposition tank are respectively provided with a separation liquid outlet, the two separation liquid outlets share one pipeline, the pipeline is provided with a heat exchange device and is connected with a solution storage tank of the liquid supply unit through a check valve and a second liquid booster pump.

Preferably, the upper part of the solution storage tank is provided with a water replenishing pipe and a hydrate accelerant replenishing pipe, the lower part of the solution storage tank is provided with a liquid outlet and a separation liquid inlet, the aqueous solution in the solution storage tank passes through the liquid outlet, then sequentially passes through the second heat exchanger, the first liquid regulating valve and the first liquid booster pump and then is divided into two pipelines, one pipeline is connected with the solution inlet at the upper part of the primary chamber of the hydration reaction tank through the first back pressure valve, and the aqueous solution enters the primary chamber to perform primary hydration reaction with gas; one path is connected with a solution inlet at the upper part of a secondary chamber of the hydration reaction tank through a second back pressure valve, and enters the secondary chamber to generate secondary hydration reaction with gas.

Preferably, the first-stage chamber and the second-stage chamber of the hydration reaction tank are separated by two layers of pressure-resistant steel plates, and heat-insulating cooling materials are filled in the steel plates to keep the temperature in the tank constant.

Preferably, the exhaust gas pretreatment unit comprises an electrostatic precipitator and a first heat exchanger which are connected in series.

Utilize above-mentioned carbon dioxide entrapment storage system to separate CO in cement industry waste gas in succession₂The method specifically comprises the following steps:

rich in CO₂The flue gas is pressurized and cooled to a set value by a gas pressurizing pump and a gas refrigerator, enters the hydrate reaction tank through a gas inlet at the bottom of a primary chamber of the hydrate reaction tank, and is in countercurrent contact with an aqueous solution containing a kinetic additive and a thermodynamic additive from a solution storage tank to generate a primary hydration reaction to generate primary CO₂Hydrate, separated N-rich₂CO in gas stream₂The content of (A) is less than 5.7%. Rich in CO₂After being condensed and demisted by a demisting net, hydrate slurry is collected to the bottom of a first-stage chamber of a hydrate reaction tank through a diversion trench, flows out from a hydrate outlet at the bottom, is conveyed to the first-stage chamber of the hydrate decomposition tank through a check valve and a liquid delivery pump, and undergoes a decomposition reaction of hydrate under the conditions of reduced pressure and heating to release CO-rich gas₂Gas, now rich in CO₂The concentration of the gas is about 75.3 percent, and the first-stage chamber of the hydrate reaction tank is separated to be rich in N₂Gas passes through a gas-liquid separatorThen the gas is discharged from a separated gas outlet at the top of the primary chamber of the hydrate reaction tank, the cold energy is recovered by a cold storage device and is introduced into N₂The storage tank stores the waste water. The recovered cold energy is used for the cooling process of the quench water storage tank.

Hydrate slurry in the first-stage chamber of the hydrate decomposition tank absorbs heat provided by the external low-temperature waste heat storage tank and decomposes to release first-stage CO₂And decomposing the gas, wherein the separation liquid after the hydrate is decomposed flows out from a separation liquid outlet at the bottom of the primary chamber of the decomposition tank, and after heat is recovered by the heat exchange device, the separation liquid is sent to a solution storage tank of the liquid supply unit through a check valve and a second liquid booster pump for cyclic utilization to participate in subsequent hydration reaction. First grade CO released from first grade chamber of decomposition tank₂After gas-liquid separation, the decomposed gas is pressurized and cooled again, enters the secondary chamber of the hydrate reaction tank from a flue gas inlet at the bottom of the secondary chamber of the hydrate reaction tank, and is in countercurrent contact with the water solution sprayed from the top of the secondary chamber to carry out secondary hydration reaction to generate secondary CO₂A hydrate. Two stage CO₂Discharging hydrate from the hydrate outlet at the bottom of the secondary chamber of the hydration reaction tank, pumping the hydrate to the secondary chamber of the hydrate decomposition tank by a liquid conveying pump, and generating CO with the concentration of more than 99 percent under the condition of reduced pressure and heating₂Gas, high concentration CO obtained₂By CO₂Cooling recovery system to CO₂And (4) storage tank.

N-rich separated from second-stage chamber of hydrate reaction tank₂The gas contains CO in relatively high concentration₂The direct discharge causes resource waste, so that the N-rich gas separated from the second-stage chamber of the hydration reaction tank₂And after liquid is removed by the gas-liquid separator, the airflow sequentially passes through the back pressure valve and the gas pressure regulating valve and enters a buffer tank of the air inlet pressurizing refrigerating unit, is uniformly mixed with the cooling flue gas, and is subjected to primary hydration reaction again, so that continuous separation and capture are realized.

Has the advantages that: compared with the prior art, the invention has the following remarkable effects:

1. combines the production characteristics of the cement industry, creatively develops a post-combustion CO capture system without large-scale reconstruction of the original system₂The method of (1); the system adopts simple process methodAnd the method has less investment by using the method for treating CO in the flue gas at the tail of the cement kiln₂Performing secondary capture and secondary decomposition to obtain CO₂The trapping is more complete and the trapped CO is more complete₂The concentration can reach more than 99 percent.

2. Compared with a stirring method, the atomization spraying method has larger contact area with gas, has more advantages in the aspects of mass transfer and gas storage density, and has higher reaction efficiency and shorter time; in order to solve the problem of hydration reaction heat in the atomization spraying process, a method of spraying quenching water into a hydration reaction tank is adopted, so that the reaction heat can be quickly transferred, and the cost is low; the temperature is directly reduced by a spraying mode, the atomized liquid beads can also participate in the hydration reaction, the effect is good, and the efficiency of the continuous hydration reaction can be improved.

3. The heat source in the hydrate decomposition process is a large amount of waste heat in the cement production process, mainly comes from a grate cooler, a rotary kiln and a decomposing furnace in the cement process production process, does not need to provide a heat source additionally, and has economical efficiency; meanwhile, the pollution caused by heat radiation in the production process is reduced; in addition, the heat energy and the cold energy of the trapping system can be recycled, and the energy consumption of the system is reduced.

4. The atomizing spraying method adopted by the invention for capturing CO₂The main component of the solution adopted in the method is water, so that the cost is low and the method has no pollution to the environment; the used hydrate accelerant can be recycled, so that the trapping cost is greatly reduced; is beneficial to industrialized large-scale capture and solves the problem of CO in the prior CCS technology₂High trapping cost and low efficiency.

Drawings

Fig. 1 is a schematic diagram of the system connection structure of the present invention.

Detailed Description

The invention is described in further detail below with reference to the drawings.

The invention discloses a method for trapping CO by using hydrate, which is suitable for the cement industry₂The system utilizes CO₂Can generate CO with water under specific conditions₂The characteristic of hydrate crystallization, cement kiln smokeCO in gas₂And (4) carrying out trapping and sealing. The method takes an aqueous solution added with dodecyl trimethyl ammonium chloride and tetrabutyl ammonium bromide in a certain proportion as a capture agent, adopts an atomization spraying mode to realize the nucleation process of the hydrate, and obtains CO-rich₂The hydrate crystals were isolated under reduced pressure and heat. CO separation by two-stage hydration reaction process and two-stage hydration decomposition process₂The obtained CO with the concentration of more than 99 percent is continuously released₂And the gas is stored through cooling, drying and compressing processes.

As shown in figure 1, the system comprises an exhaust gas pretreatment unit, an inlet gas pressurization refrigeration unit, a liquid supply unit, a two-stage combined hydrate synthesis decomposition unit and CO₂And a recovery unit.

The waste gas pretreatment unit comprises an electrostatic dust collector 3 and a first heat exchanger 4 which are connected in sequence, and aims to purify and separate heavy metals (such as mercury, nickel, lead, arsenic and the like) and dust pollutants in kiln tail waste gas to obtain pure CO-rich gas₂Flue gas to perform capture. Flue gas from a kiln tail chimney is connected with an inlet of an electrostatic dust collector 3 through a pipeline, a first gas flowmeter 1 and a first gas regulating valve 2 are arranged on the flue gas pipeline between a kiln tail exhaust fan and the electrostatic dust collector 3, purified flue gas treated by the electrostatic dust collector enters a first heat exchanger 4 from an inlet of the first heat exchanger 4 for cooling, recovered heat is used for a hydrate decomposition process, and cooled flue gas flows into an air inlet pressurization refrigeration unit. Dust and heavy metal pollutants contained in the kiln tail waste gas are removed through an electrostatic dust collector, and the purified and removed dust enters a raw material mill through a pipeline and is used as a raw material for cement production.

The intake air supercharging and refrigerating unit comprises a gas buffer tank 7, a first gas compressor 15, a first gas refrigerator 16, a second gas flowmeter 17 and a second gas regulating valve 18. The gas outlet of the gas buffer tank 7 is connected to the inlet of a first gas compressor 15 via a first shut-off valve 14, and the outlet of the first gas compressor 15 is connected to the inlet of a first gas refrigerator 16. The gas buffer tank is provided with 7 a second stop valve 6 and a pressure gauge 5 to monitor the gas pressure in the tank in real time. The gas buffer tank 7 is connected with an inlet of a first gas compressor 15 through a first stop valve 14, the pressure of the flue gas flowing out of the buffer tank 7 is increased to a pressure above a phase equilibrium pressure corresponding to the hydration reaction temperature through the first gas compressor 15, and a second gas flowmeter 17 and a second gas regulating valve 18 are arranged on a pipeline of the first gas refrigerator 16 communicated with the first-stage chamber of the hydration reaction tank.

The liquid supply unit comprises a solution storage tank 10, a second heat exchanger 11, a first liquid regulating valve 12 and a first liquid booster pump 13. The upper end of the solution storage tank 10 is provided with a water supplementing pipe 8 and a hydrate accelerant supplementing pipe 9, the water supplementing pipe 8 is used for supplementing water, and the hydrate accelerant supplementing pipe 9 is used for supplementing a kinetic additive and a kinetic additive for accelerating the hydration reaction rate. The lower part of the solution storage tank 10 is provided with a mixed solution outlet and a separation liquid inlet. The water solution uniformly mixed in the solution storage tank 10 passes through a mixed solution outlet, sequentially passes through the second heat exchanger 10, the first liquid regulating valve 11 and the first liquid booster pump 13, and then is divided into two pipelines, one pipeline is connected with a solution inlet at the upper part of the primary chamber 20A of the hydration reaction tank through the first back pressure valve 33, and enters the primary chamber of the hydration reaction tank to perform primary hydration reaction with gas; one path is connected with a solution inlet at the upper part of a secondary chamber 20B of the hydration reaction tank through a second backpressure valve 34, and enters the secondary chamber to perform secondary hydration reaction with gas.

The kinetic additive in the hydrate accelerant supplementing pipe of the solution storage tank 10 is dodecyl trimethyl ammonium chloride, and the mass fraction of the kinetic additive is 0.08-0.14 wt%. The thermodynamic additive in the additive supplementing pipe is tetrabutylammonium bromide solution, and the mass fraction is 6-12 wt%. Under the action of the kinetic additive and the thermodynamic additive, the gas-liquid interfacial tension is obviously reduced and the gas-liquid contact area is increased. CO 2₂The hydrate formation rate is significantly enhanced.

The two-stage combined hydrate synthesis decomposition unit comprises a first-stage chamber 20A of a hydration reaction tank, a second-stage chamber 20B of the hydration reaction tank, a first-stage chamber 23A of the hydration decomposition tank and a second-stage chamber 23B of the hydration decomposition tank. The first-stage chamber 20A and the second-stage chamber 20B of the hydration reaction tank are hollow, and the top and the bottom are both arc-shaped. The first-stage chamber 20A of the hydration reaction tank and the second-stage chamber 20B of the hydration reaction tank are separated by two layers of pressure-resistant steel plates, and heat-insulating cooling materials are filled in the steel plates to keep the temperature in the tank constant. In order to solve the problem that the hydration reaction can not be continuously carried out due to the fact that the generated heat in the spraying process can not be timely dissipated, quenching water nozzles are respectively arranged in the middle of the gas phase reaction areas of the first-stage chamber 20A and the second-stage chamber 20B of the hydration reaction tank, and the quenching water can absorb part of the reaction heat to form liquid drops and participate in the hydration reaction. The quenching water pipe is arranged at the gap between the two layers of pressure-resistant steel plates of the first-stage chamber 20A and the second-stage chamber 20B of the hydration reaction tank, and the quenching water is stored by a quenching water storage tank arranged outside the hydration reaction tank and is sent into the first-stage chamber 20A and the second-stage chamber 20B of the hydration reaction tank through the quenching water pipe.

The tops of the first-stage chamber 20A and the second-stage chamber 20B of the hydration reaction tank are respectively provided with a solution inlet and a separation gas outlet, and the solution inlets are respectively provided with a filtering membrane for filtering impurities in the mixed aqueous solution so as to prevent the atomizing nozzle from being blocked. The separated gas outlet is used for discharging the separated gas after the hydration reaction. The bottoms of the first-stage chamber 20A and the second-stage chamber 20B of the hydration reaction tank are provided with a flue gas inlet and a hydrate outlet. The hydrate outlet at the bottom of the first-stage chamber 20A of the hydration reaction tank is connected with the hydrate inlet at the bottom of the first-stage chamber 23A of the hydration decomposition tank through a third back pressure valve. A hydrate outlet at the bottom of the second-stage chamber 20B of the hydration reaction tank is connected with a hydrate inlet at the bottom of the second-stage chamber 23B of the hydration decomposition tank through a fourth backpressure valve, and a separated gas outlet at the top of the second-stage chamber 20B of the hydration reaction tank is connected with a separated gas inlet of the buffer tank through a fifth backpressure valve and a third gas flow meter. Gas-liquid separation devices are arranged at the tops of the first-stage chamber 20A and the second-stage chamber 20B of the hydration reaction tank and used for solving the problem of solution entrainment in the separated gas, and the separated N-rich gas₂The airflow enters N after being recovered by the cold energy recovery device through the outlet arranged at the top₂A collector. The inner walls of the first-stage chamber 20A and the second-stage chamber 20B of the hydration reaction tank are provided with demisting nets with small apertures, and the demisting nets are coated with hydrophobic coatings, so that hydrates with water-in-oil structures cannot be bonded on the demisting nets to cause intracavity blockage. A flow guide groove is arranged at the lower side of the demisting net and used for capturing waterAnd synthesizing the hydrate liquid drops after reaction, and simultaneously guiding the hydrate slurry to converge. The absolute pressure in the first-stage chamber 20A and the absolute pressure in the second-stage chamber 20B of the hydration reaction tank are kept at 3.0-15.0 MP, and the temperature is kept at 1.0-5.0 ℃. The upper parts of the first-stage chamber 20A and the second-stage chamber 20B of the hydration reaction tank are respectively provided with three hydraulic atomization spraying devices, a wide-angle type spraying nozzle is adopted to form a solution spraying tent, and the spraying devices can control the size of water drops according to actual conditions.

The hydration decomposition tank comprises a first-stage chamber 23A of the hydration decomposition tank and a second-stage chamber 23B of the hydration decomposition tank which are arranged up and down, wherein the first-stage chamber 23A of the hydration decomposition tank and the second-stage chamber 23B of the hydration decomposition tank are respectively provided with a hydrate inlet, a decomposition gas outlet, a separation liquid outlet and a window. The top of the first-stage chamber 23A of the hydration decomposition tank is provided with a decomposition gas outlet, and the decomposition gas of the first-stage chamber 23A of the hydration decomposition tank is connected with a flue gas inlet at the bottom of the second-stage chamber 20B of the hydration reaction tank through a third heat exchanger 24, a second gas compressor 25 and a second gas refrigerator 26. Decomposed gas outlet and CO of secondary chamber 23B of hydration decomposition tank₂Cooling CO of recovery unit₂The inlet of the drying device 37 is connected. Gas-liquid separators are arranged at the top parts in the first-stage chamber 23A and the second-stage chamber 23B of the hydration decomposition tank and are used for gas-liquid separation after decomposition. The shell of the hydration decomposition tank is provided with a heat insulation interlayer, and heat insulation materials are filled in the heat insulation interlayer and used for keeping the temperature in the hydration decomposition tank constant. The lower part is provided with a spiral heat exchanger, the working medium in the spiral heat exchanger is water, the required heat source is the waste heat from a grate cooler, a rotary kiln and a decomposing furnace of a cement production system, the waste heat from the grate cooler, the rotary kiln and the decomposing furnace of the cement kiln is stored by a low-temperature waste heat storage tank 27, and the low-temperature waste heat storage tank 27 supplies heat for a primary chamber 23A of a hydration decomposing tank and a secondary chamber 23B of the hydration decomposing tank. The hydration decomposition process can be monitored through a window. The working pressure in the hydration decomposition tank is 0.2-0.6 Mpa, and the reaction temperature is 6-15 ℃.

CO₂The cooling recovery unit comprises CO₂Drying apparatus 37, CO₂Compressor 38, fourth heat exchanger 39, CO₂A storage tank 40. High-purity CO decomposed from second-stage roof of hydration reaction decomposition tank₂Through a pressure reducing valveTo CO₂CO is dehydrated in the drying device 37₂Sequentially through CO₂The compression device 38 and the fourth heat exchanger 39 enter into the CO₂A storage tank 40. High purity CO obtained₂The compressed gas can be used in commercial ways such as industry and the like. The waste heat recovered by the fourth heat exchanger 39 can be used for CO₂And (3) decomposing the hydrate.

The shell of the hydration reaction tank, the shell of the solution storage tank and the shell of the gas buffer tank are all provided with cooling jackets, the cooling jackets are filled with circulating cooling water, and the cooling jackets are arranged to pre-cool the flue gas and the aqueous solution which participate in the reaction, so that the stability of the hydration reaction condition is improved.

The working process is as follows:

the flue gas from a kiln tail chimney is connected with an inlet of an electrostatic dust collector 3 through a pipeline, the purified flue gas treated by the electrostatic dust collector enters a first heat exchanger 4 from the inlet of the first heat exchanger 4 for cooling, the recovered heat is used for the hydrate decomposition process, the cooled flue gas enters a gas buffer tank 7 again, the flue gas flowing out of the buffer tank 7 is boosted to a phase equilibrium pressure corresponding to the hydration reaction temperature through a first gas compressor 15, then the flue gas is led into a first gas refrigerator 16 to be cooled, the temperature of the flue gas cooled by the first gas refrigerator 16 is about 1-8 ℃, the cooled flue gas passes through a second gas flowmeter 17 and a second gas regulating valve 18, enters a hydration reaction tank from the lower end of a first-stage chamber 20A of the hydration reaction tank, and is in countercurrent contact with the solution from a solution storage tank 10 to perform a first-stage hydration reaction, rich CO produced₂The hydrate is captured by a demisting net on the inner wall of the primary chamber 20A of the hydration reaction tank and is drained to the bottom of the primary chamber 20A of the hydration reaction tank through a diversion trench. At this time, CO₂The hydrate formation pressure drop is 1.5MPa and about 75% of CO₂React with water to form CO₂A hydrate. And water and hydrate accelerant are intermittently supplemented to the solution storage tank 10 through a water supplementing pipe 8 and a hydrate accelerant supplementing pipe 9 respectively.

N-rich separated by first-stage hydration reaction₂Gas is separated from gas and liquid through a wire mesh and then is discharged from a separated gas outlet at the top of a first-stage chamber of the hydration reaction tank,and enters N after the cold energy is recovered by the cold energy recovery device 35₂For storage and utilization in the storage tank 36.

CO-rich gas discharged from the bottom of the first-stage chamber 20A of the hydration reaction tank₂The hydrate enters the first-stage chamber 23A of the hydration decomposition tank from the hydrate inlet at the lower part of the first-stage chamber 23A of the hydration decomposition tank through the third back pressure valve 21, the hydration decomposition tank 23A is heated by the heat energy in the low-temperature waste heat storage tank 27, hydrate slurry entering the first-stage chamber 23A of the hydration decomposition tank is decomposed, and decomposed gas is discharged from the outlet at the top of the first-stage chamber of the hydration decomposition tank through the gas-liquid separator at the top of the first-stage chamber 23A of the hydration decomposition tank. At this time, CO in the gas₂The concentration was about 75%.

The separated gas overflowing from the top of the primary chamber 23A of the hydration decomposition tank is cooled and the waste heat is recycled through the third heat exchanger 24, the heat exchange of the separated gas directly absorbs and accumulates high-temperature heat energy in a fluid form, the cooled separated gas is introduced into the second gas compressor 25 to be subjected to gas pressurization operation, the separated gas refrigerated by the second gas refrigerator 26 is introduced into the secondary chamber 20B of the hydration reaction tank to be in countercurrent contact with the solution sprayed from the top to generate secondary hydration reaction, demisted by the demisting net on the side wall of the secondary chamber and drained to the bottom accumulated in the chamber, and the separated gas is discharged through a hydrate discharge port at the bottom of the secondary chamber. CO in separated gas of secondary chamber 20B of hydration reaction tank₂The concentration of the gas is about 27%, in order to avoid resource waste, the gas separated by the second-stage hydration reaction is subjected to gas-liquid separation by water and a wire mesh above a second-stage chamber 20B of the reaction tank, then sequentially passes through a separated gas outlet above the second-stage chamber, a gas pressure reducing valve 32 and a third gas flowmeter 31, enters the buffer tank 7 from a separated gas inlet at the bottom of the buffer tank, is pressurized by the first gas compressor 15, is cooled by the first gas cooler 16, and then is subjected to the first-stage hydration reaction again.

The hydrate slurry after the secondary hydration reaction of the secondary chamber 20B of the hydration reaction tank enters the secondary chamber 23B of the hydration decomposition tank from the hydrate inlet below the secondary chamber 23B of the hydration decomposition tank through a fourth back pressure valve 22, and is heated by the heat of an external low-temperature waste heat storage tank 27, so that CO in the hydrate is heated₂The gas is released and further collected. Low temperature waste heatThe storage tank device 27 can make full use of waste heat in the cement production process, and solves the problem that the existing waste gas waste heat boiler can only utilize high-temperature waste heat and a large amount of low-temperature waste gas waste heat, so that the environmental pollution is caused.

Then high-concentration CO synthesized and decomposed by secondary hydration reaction₂CO via gas pressure reducing valve 30₂In the drying device 37, a water-absorbing drying treatment is performed to form dry CO₂Gas, CO of dry gas₂The concentration of the catalyst reaches more than 99 percent, and then the catalyst is subjected to CO treatment₂The compression device 38 performs gas compression treatment, and the gas enters CO after being subjected to heat exchange by the fourth heat exchanger 39₂As CO in the storage tank 40₂And (5) storing the finished product. CO obtained₂The finished product can be used for chemical synthesis, dry ice preparation, food and drug preparation, oil displacement in oil fields and the like.

Thus, the CO contained in the treated flue gas₂The amount is extremely low, so that the environment is not seriously polluted, the emission reduction requirement of greenhouse gas in high-emission industries is met, the environment is effectively protected, and meanwhile, the used decomposition heat source is derived from waste heat in the production process of the cement industry, so that the utilization efficiency of energy is improved. The hydrate method-based cement industry carbon dioxide capturing and storing device has the advantages of simple process and low cost, can effectively recover carbon dioxide in waste gas after cement production, and obviously reduces CO to the atmosphere₂Discharge amount and can produce economic benefits. In the face of the historical mission of carbon emission reduction in a new period and a new stage, the cement great career is favorably pushed to the full green transformation good future.