CN113697809B - Cement kiln flue gas carbon dioxide trapping and storing system based on hydrate method - Google Patents
Cement kiln flue gas carbon dioxide trapping and storing system based on hydrate method Download PDFInfo
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- CN113697809B CN113697809B CN202110835921.XA CN202110835921A CN113697809B CN 113697809 B CN113697809 B CN 113697809B CN 202110835921 A CN202110835921 A CN 202110835921A CN 113697809 B CN113697809 B CN 113697809B
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B32/00—Carbon; Compounds thereof
- C01B32/50—Carbon dioxide
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B7/00—Hydraulic cements
- C04B7/36—Manufacture of hydraulic cements in general
- C04B7/43—Heat treatment, e.g. precalcining, burning, melting; Cooling
- C04B7/47—Cooling ; Waste heat management
- C04B7/475—Cooling ; Waste heat management using the waste heat, e.g. of the cooled clinker, in an other way than by simple heat exchange in the cement production line, e.g. for generating steam
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P20/00—Technologies relating to chemical industry
- Y02P20/10—Process efficiency
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P20/00—Technologies relating to chemical industry
- Y02P20/10—Process efficiency
- Y02P20/129—Energy recovery, e.g. by cogeneration, H2recovery or pressure recovery turbines
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P40/00—Technologies relating to the processing of minerals
- Y02P40/10—Production of cement, e.g. improving or optimising the production methods; Cement grinding
- Y02P40/18—Carbon capture and storage [CCS]
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Abstract
The invention discloses a cement kiln flue gas carbon dioxide capturing and storing system based on a hydrate method, which comprises the following steps ofThe waste gas pretreatment unit and the air inlet pressurizing and refrigerating unit are connected, the outlet of the air inlet pressurizing and refrigerating unit is connected with the inlet of the first-stage chamber of the hydration reaction tank, the outlet of the first-stage chamber of the hydration reaction tank is connected with the inlet of the first-stage chamber of the hydration decomposition tank, the outlet of the first-stage chamber of the hydration decomposition tank is connected with the inlet of the second-stage chamber of the hydration reaction tank, the outlet of the second-stage chamber of the hydration reaction tank is connected with the inlet of the second-stage chamber of the hydration decomposition tank, the second-stage separation is carried out, and the outlet of the second-stage chamber of the hydration decomposition tank is connected with CO 2 A cooling recovery unit; and a liquid supply unit 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 is realized by two-stage hydration reaction and two-stage hydration decomposition 2 Is released continuously to obtain CO with concentration as high as 99% 2 The gas is stored by cooling, drying and compression.
Description
Technical Field
The invention relates to a carbon capture system for cement industry, in particular to a carbon dioxide capture and storage system for cement kiln flue gas based on a hydrate method.
Background
The cement production is a high energy consumption process, the energy consumption accounts for about 2% of the global primary energy consumption, and the cement industry becomes a huge carbon dioxide emission source due to the fact that carbon-intensive fuels such as coal and the like are mainly utilized in the production process. In addition to the energy consumption process, the calcination process of cement clinker also generates a large amount of carbon dioxide. At present, the cement industry in China discharges CO annually 2 Over 12 hundred million tons, and has a large amount of exhaust gas waste heat and exhaust gas pollutant emissions, and the greenhouse effect caused by excessive carbon dioxide and pollutants in the atmosphere has serious influence on the ecological environment in which human beings depend to live.
Carbon capture and sequestration technology (CCS) is one of the core strategies of carbon dioxide comprehensive treatment schemes, and has the advantages of not only effectively realizing carbon emission reduction, but also producing economic benefits, and reducing capture cost without large-scale modification of production systems. CCS technology consists of two parts, carbon capture and carbon sequestration. The carbon trapping technology is mainly divided into three types, namely pre-combustion trapping, oxygen-enriched combustion technology and post-combustion trapping. The pre-combustion trapping is a method of first generating synthesis gas by gasification reaction of fuel, then further generating hydrogen and high-concentration carbon dioxide by reaction, and finally carrying out carbon trapping. This trapping technique works only on the fuel combustion process and cannot capture carbon dioxide generated by the raw material calcination process, and is therefore not suitable for the cement industry. The oxyfuel combustion technology utilizes pure oxygen to replace air to participate in the combustion process, so that high-concentration carbon dioxide is generated, and further capturing and storage are facilitated. The oxygen-enriched combustion technology has the defects of higher reaction temperature, high energy consumption and relatively higher investment requirement. Post-combustion capture refers to the capture and separation of CO from flue gas discharged from a production system 2 The technology is suitable for low concentration CO 2 The capture of the cement plant is wide in application range, and the cement plant is saved for the existing cement plantThe modification of the combustion process and existing facilities is eliminated. The post-combustion trapping technology has many implementation means, and is mainly divided into a chemical absorption method, a physical absorption method, a membrane separation method, a low-temperature distillation method and the like, and the CO is the most widely used at present 2 The trapping method is an alcohol amine absorption method. The alcohol amine method can capture 85 to 95 percent of CO 2 Absorbs CO 2 The solvent of (2) is subjected to temperature rising desorption to obtain high-concentration CO 2 And 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.
Separation of CO by hydrate method 2 In recent years, attention has been paid to the fact that the use of such a material has been widely paid. Hydrates are non-stoichiometric, crystalline structure compounds, gas molecules of different molecular weights, e.g. CO 2 、N 2 、H 2 And forming cage crystals with different structures by hydrogen bond crystallization with water molecules under certain temperature and pressure, wherein the water molecules in the crystal structures are combined by hydrogen bond, and gas molecules are combined with the water molecules by Van der Waals force. The principle of hydrate separation is that the pressure and temperature required by the generation of hydrate by using different gas molecules are different, and the gas easy to generate hydrate is enriched in the hydrate phase by controlling the temperature and pressure in the growth process of the hydrate, so that the purpose of further separation is achieved. Separation of CO by hydrate method 2 Low energy consumption, simple operation, trapping cost of about 50% of chemical absorption method, and is considered as the long-term CO with the most development potential 2 Trapping technology.
Currently, whether the process of separating gas by a hydrate method can be industrially limited by the nucleation speed of gas hydrate and the gas separation efficiency, especially the nucleation speed of gas hydrate is limited by the capture of CO by the hydrate method 2 Key factors of the technology. At present, a hydrate method has a certain achievement in the field of carbon capture, but has certain problems such as incapability of continuous operation in high-flow flue gas, slow nucleation of hydrate, incapability of timely dissipation of generated heat and accumulation of generated heat in liquid drops and the like. Based on the above shortcomings, there is an urgent need to develop a hydrate method equipment system which is efficient, environment-friendly and capable of fully utilizing waste heat of cement industrySo as to realize the carbon emission reduction prospect of the cement industry.
Disclosure of Invention
The invention aims to: the invention aims to provide a cement kiln flue gas carbon dioxide trapping and storing system based on a hydrate method, which has low cost, no pollution and good trapping effect.
The technical scheme is as follows: the invention relates to a cement kiln flue gas carbon dioxide capturing and storing system based on a hydrate method, which comprises an exhaust gas pretreatment unit and an air inlet pressurizing and refrigerating unit which are sequentially connected, wherein the outlet of the air inlet pressurizing and refrigerating unit is connected with the inlet of a first-stage chamber of a hydration reaction tank for carrying out first-stage hydration reaction, the outlet of the first-stage chamber of the hydration reaction tank is connected with the inlet of a first-stage chamber of a hydration decomposition tank for carrying out first-stage separation, the outlet of the first-stage chamber of the hydration decomposition tank is connected with the inlet of a second-stage chamber of the hydration reaction tank for carrying out second-stage hydration reaction, the outlet of the second-stage chamber of the hydration reaction tank is connected with the inlet of the second-stage chamber of the hydration decomposition tank for carrying out second-stage separation, and the outlet of the second-stage chamber of the hydration decomposition tank is connected with CO 2 A cooling recovery unit; the device also comprises a liquid supply unit for supplying liquid to the first-stage chamber of the hydration reaction tank and the second-stage chamber of the hydration reaction tank 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 a liquid supply unit and used for the nucleation reaction of the hydrate; the quenching water device is used for radiating heat generated in the atomizing spraying process and participating in hydration reaction.
Preferably, the quenching water device comprises quenching water nozzles respectively arranged in the first-stage chamber of the hydration reaction tank and the second-stage chamber of the hydration reaction tank, and a quenching water storage tank for supplying water to the quenching water nozzles 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 an aqueous solution containing a hydrate promoter and a separated gas outlet for discharging separated gas after hydration reaction; and the bottoms of the first-stage chamber and the second-stage chamber of the hydration reaction tank are respectively provided with a flue gas inlet and a hydrate outlet.
Preferably, the first-stage chamber and the second-stage chamber of the hydration decomposing tank are longitudinally arranged in the hydration decomposing tank, the bottom of the hydration decomposing tank is connected with a low-temperature waste heat storage tank for supplying heat to the first-stage chamber and the second-stage chamber of the hydration decomposing tank, and the low-temperature waste heat storage tank is used for recovering waste heat of a cement kiln grate cooler, a rotary kiln and a decomposing furnace.
Preferably, a hydrate inlet at the bottom of the first-stage chamber of the hydration-decomposition tank is connected with a flue gas outlet at the bottom of the first-stage chamber of the hydration-decomposition tank, the hydrate inlet at the bottom of the first-stage chamber of the hydration-decomposition tank is connected with a flue gas outlet at the bottom of the first-stage chamber of the hydration-decomposition tank, and a decomposed gas outlet at the top of the first-stage chamber of the hydration-decomposition tank is connected with a flue gas inlet at the bottom of the second-stage chamber of the hydration-reaction tank through a third heat exchanger, a second gas compressor and a second gas refrigerator; the hydrate inlet at the bottom of the second-stage chamber of the hydration-decomposition tank is connected with the flue gas outlet at the bottom of the second-stage chamber of the hydration reaction tank; the decomposed gas outlet and CO at the top of the secondary chamber of the hydration decomposing tank 2 Cooling CO of recovery unit 2 The 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 separating liquid outlet, the two separating liquid outlets share a pipeline, and 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 supplementing pipe and a hydrate accelerator supplementing pipe, the lower part of the solution storage tank is provided with a liquid outlet and a separating liquid inlet, the aqueous solution in the solution storage tank is divided into two pipelines after passing through the liquid outlet and then sequentially passing through a second heat exchanger, a first liquid regulating valve and a first liquid booster pump, and one pipeline is connected with the solution inlet at the upper part of a primary chamber of the hydration reaction tank through a first back pressure valve and enters the primary chamber to carry out 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 carry out secondary hydration reaction with gas.
Preferably, the first-stage chamber of the hydration reaction tank and the second-stage chamber of the hydration reaction tank are separated by two layers of pressure-resistant steel plates, and the heat-insulating cooling material is 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 connected in sequence.
CO in cement industrial waste gas is continuously separated by utilizing the carbon dioxide capturing and storing system 2 Specifically comprising the following steps:
rich in CO 2 The flue gas is pressurized and cooled to a set value by a gas booster pump and a gas refrigerator, enters the hydrate reaction tank through an air inlet at the bottom of a first-stage chamber of the hydrate reaction tank, and contacts with an aqueous solution containing a kinetic additive and a thermodynamic additive from a solution storage tank in a countercurrent manner to generate first-stage hydration reaction to generate first-stage CO 2 Hydrate, separated N-rich 2 CO in gas stream 2 The content of (2) is less than 5.7%. Rich in CO 2 The hydrate slurry is condensed and defogged by a defogging net, and then 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 a hydrate decomposition tank through a check valve and a liquid conveying pump, and undergoes a decomposition reaction of the hydrate under the conditions of decompression and heating to release rich CO 2 Gas, at this time rich in CO 2 The concentration of the gas is about 75.3%, and the hydrate reaction tank is rich in N separated from the primary chamber 2 After the gas passes through the gas-liquid separator, the gas is discharged from a separated gas outlet at the top of a primary chamber of the hydrate reaction tank, and the cold energy is recovered through a cold accumulation device and is introduced into N 2 The storage tank stores. The recovered cold energy is used for the cooling process of the quench water storage tank.
Hydrate slurry in first-stage chamber of hydrate decomposing tank absorbs heat provided by external low-temperature waste heat storage tank to decompose and release first-stage CO 2 After decomposing gas and decomposing hydrate, separating liquid flows out from a separating liquid outlet at the bottom of a first-stage chamber of the decomposing tank, heat is recovered by a heat exchange device, and then the separating liquid is pumped into a solution storage tank of a liquid supply unit through a check valve and a second liquid booster pump for cyclic utilization to participate in subsequent hydration reaction. First-stage CO released by first-stage chamber of decomposing tank 2 After gas-liquid separation, the decomposed gas is pressurized and cooled again, and enters the hydrate reaction tank secondary chamber from a flue gas inlet at the bottom of the hydrate reaction tank secondary chamberAnd the reaction product is in countercurrent contact with the water solution sprayed on the top of the secondary chamber to carry out secondary hydration reaction, thus generating secondary CO 2 A hydrate. Secondary CO 2 The hydrate is discharged from a hydrate outlet at the bottom of the second-stage chamber of the hydration reaction tank, is pumped into the second-stage chamber of the hydrate decomposition tank through a liquid conveying pump, and generates CO with the concentration of more than 99 percent under the condition of reduced pressure and heating 2 Gas, high concentration CO obtained 2 Through CO 2 The cooling recovery system is sent to CO 2 And a storage tank.
N-rich separated from secondary chamber of hydrate reaction tank 2 The gas contains CO with higher concentration 2 The direct discharge will cause the waste of resources, thus separating the secondary chamber of the hydration reaction tank into N-rich 2 The gas flow enters a buffer tank of the air inlet pressurizing and cooling unit through a back pressure valve and a gas pressure regulating valve after liquid removal of a gas-liquid separator, is uniformly mixed with cooling smoke, and is subjected to primary hydration reaction again, so that continuous separation and capture are realized.
The beneficial effects are 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 trapping method without large-scale modification of the original system 2 Is a method of (2); the system adopts a hydrate method with simple process and small investment, and uses CO in the tail smoke of the cement kiln 2 Performing secondary capture and secondary decomposition to make CO 2 Is more complete and thorough in capturing CO 2 The concentration can reach more than 99 percent.
2. Compared with a stirring method, the atomizing spraying method has larger contact area with gas, has more advantages in 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 quench water into a hydration reaction tank is adopted, so that the reaction heat can be quickly transferred, and the cost is low; the atomized liquid beads can also participate in hydration reaction by directly cooling in a spraying mode, so that the effect is good, and the efficiency of continuous hydration reaction can be improved.
3. The heat source in the hydrate decomposition process is derived from a large amount of waste heat in the cement production process and mainly derived from a grate cooler, a rotary kiln and a decomposing furnace in the cement process production process, and the heat source is not required to be additionally provided, so that the economy is realized; at the same time, the pollution caused by heat radiation in the production process is reduced; in addition, the heat energy and cold energy of the trapping system can be recycled, so that the energy consumption of the system is reduced.
4. The invention adopts an atomization spraying method to trap CO 2 The main component of the solution adopted in the method is water, the cost is low, and the environment is not polluted; the used hydrate accelerant can be recycled, so that the trapping cost is greatly reduced; is beneficial to industrialized large-scale trapping and solves the problem of CO in the prior CCS technology 2 High trapping cost and low efficiency.
Drawings
Fig. 1 is a schematic diagram of a system connection structure according to the present invention.
Description of the embodiments
The invention is described in further detail below with reference to the drawings.
The invention discloses a method for capturing CO by utilizing hydrate, which is suitable for the cement industry 2 The system utilizing CO 2 Can generate CO with water under specific conditions 2 The characteristic of hydrate crystallization is that for CO in the flue gas of a cement kiln 2 And (5) collecting and sealing. The method takes an aqueous solution added with dodecyl trimethyl ammonium chloride and tetrabutyl ammonium bromide in a certain proportion as a capturing agent, adopts an atomizing spraying mode to realize the nucleation process of the hydrate, and obtains the CO-enriched product 2 The hydrate crystals are separated under reduced pressure and heat. CO is realized by a two-stage hydration reaction process and a two-stage hydration decomposition process 2 Continuous release of CO with concentration up to 99% or more 2 The gas is stored by cooling, drying and compression processes.
As shown in FIG. 1, the system comprises an exhaust gas pretreatment unit, an air inlet pressurizing and refrigerating unit, a liquid supply unit, a two-stage combined hydrate synthesis and decomposition unit and CO 2 And a recovery unit.
The waste gas pretreatment unit comprises an electrostatic precipitator 3 and a first electric precipitator connected in sequenceA heat exchanger 4 for purifying and separating heavy metals (such as mercury, nickel, lead, arsenic, etc.) and dust pollutants in the kiln tail gas to obtain pure CO-rich gas 2 Flue gas to effect capture. The flue gas from the kiln tail chimney is connected with the inlet of the electrostatic precipitator 3 through a pipeline, the first gas flowmeter 1 and the first gas regulating valve 2 are arranged on a flue gas pipeline between the kiln tail exhaust fan and the electrostatic precipitator 3, purified flue gas treated by the electrostatic precipitator enters the 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, and the cooled flue gas flows into the air inlet supercharging refrigerating unit. Dust and heavy metal pollutants contained in kiln tail waste gas are removed through an electrostatic precipitator, and the purified and removed dust enters a raw material mill through a pipeline and is used as cement production raw materials.
The air intake supercharging refrigerating unit comprises a gas buffer tank 7, a first gas compressor 15, a first gas cooler 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 through a first shut-off valve 14, and the outlet of the first gas compressor 15 is connected to the inlet of a first gas cooler 16. The gas buffer tank 7 is provided with a second shut-off 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 flue gas flowing out of the gas buffer tank 7 is boosted to be higher than the 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 kinetic additives and kinetic additives 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 solution inlet. The uniformly mixed aqueous solution in the solution storage tank 10 sequentially passes through the second heat exchanger 11, the first liquid regulating valve 12 and the first liquid booster pump 13 through a mixed solution outlet and then is divided into two pipelines, one pipeline is connected with a solution inlet at the upper part of the first-stage chamber 20A of the hydration reaction tank through the first back pressure valve 33, and enters the first-stage chamber of the hydration reaction tank to carry out first-stage hydration reaction with gas; one path is connected with a solution inlet at the upper part of the secondary chamber 20B of the hydration reaction tank through a second back pressure valve 34, and enters the secondary chamber to carry out secondary hydration reaction with gas.
The dynamic additive in the hydrate accelerator supplementing pipe of the solution storage tank 10 is dodecyl trimethyl ammonium chloride, and the mass fraction of the dynamic additive is 0.08-wt% -0.14-wt%. The thermodynamic additive in the additive replenishing pipe is tetrabutylammonium bromide solution, and the mass fraction of the thermodynamic additive is 6 wt% -12 wt%. The hydration reaction is under the action of dynamic additive and thermodynamic additive, the gas-liquid interfacial tension is obviously reduced, and the gas-liquid contact area is increased. CO 2 The hydrate formation rate is significantly enhanced.
The two-stage combined hydrate synthesis and decomposition unit comprises a hydration reaction tank primary chamber 20A, a hydration reaction tank secondary chamber 20B, a hydration decomposition tank primary chamber 23A and a hydration decomposition tank secondary chamber 23B. The hydration reaction tank primary chamber 20A and the hydration reaction tank secondary chamber 20B are hollow, and the top and the bottom are arc-shaped. 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 the heat-insulating cooling material is filled in the steel plates to keep the temperature in the tank constant. In order to solve the problem that hydration reaction cannot be continuously carried out due to the fact that generated heat in the spraying process cannot be timely dissipated, quenching water nozzles are respectively arranged in the middle of gas phase reaction areas of the primary chamber 20A of the hydration reaction tank and the secondary chamber 20B of the hydration reaction tank, and quenching water can absorb part of reaction heat to form liquid drops to participate in the hydration reaction. The quenching water pipe is arranged at the gap of 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 are respectively provided with a solution inlet and a solution outletThe separating gas outlet and the solution inlet are both provided with filtering membranes 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-decomposition 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. The hydrate outlet at the bottom of the hydration-reaction tank secondary chamber 20B is connected with the hydrate inlet at the bottom of the hydration-decomposition tank secondary chamber 23B through a fourth back pressure valve, and the separated gas outlet at the top of the hydration-reaction tank secondary chamber 20B is connected with the separated gas inlet of the buffer tank through a fifth gas back pressure valve and a third gas flowmeter. The tops of the first-stage chamber 20A and the second-stage chamber 20B of the hydration reaction tank are respectively provided with a gas-liquid separation device for solving the problem of solution entrainment in the separated gas, and the separated N-enriched gas is provided with a gas-liquid separation device 2 The air flow passes through an outlet arranged at the top part and enters N after cold energy is recovered by a cold energy recovery device 2 A collector. The inner walls of the first-stage chamber 20A and the second-stage chamber 20B of the hydration reaction tank are respectively provided with a demisting net with small apertures, and the demisting nets are coated with a hydrophobic coating, so that the hydrate of the water-in-oil structure cannot be adhered to the demisting nets to cause the blockage of the cavity. And the lower side of the demisting net is provided with a diversion trench for capturing hydrate liquid drops after hydration reaction and guiding hydrate slurry to flow together. Absolute pressure in the hydration reaction tank primary chamber 20A and absolute pressure in the hydration reaction tank secondary chamber 20B are kept at 3.0-15.0 MP, and temperature is kept at 1.0-5.0 ℃. Three hydraulic atomization spraying devices are respectively arranged on the upper parts of the first-stage chamber 20A of the hydration reaction tank and the second-stage chamber 20B of the hydration reaction tank, a wide-angle spray nozzle is adopted to form a solution spraying tent, and the spraying devices can control the water drop size according to actual conditions.
The hydration decomposing tank comprises a hydration decomposing tank primary chamber 23A and a hydration decomposing tank secondary chamber 23B which are arranged up and down, wherein the hydration decomposing tank primary chamber 23A and the hydration decomposing tank secondary chamber 23B are respectively provided with a hydrate inlet, a decomposing gas outlet, a separating 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 passes through a third heat exchanger 24 and a second gas compressor 25The second gas refrigerator 26 is connected to the flue gas inlet at the bottom of the hydration reaction tank secondary chamber 20B. Decomposed gas outlet and CO of hydration-decomposition tank secondary chamber 23B 2 Cooling CO of recovery unit 2 The inlet of the drying device 37 is connected. The top of the first-stage chamber 23A and the second-stage chamber 23B of the hydration decomposing tank are provided with gas-liquid separators for separating decomposed gas and liquid. The hydration decomposing tank shell is provided with a heat preservation interlayer, and a heat preservation material is filled in the heat preservation interlayer and used for keeping the temperature in the hydration decomposing tank constant. The lower part is provided with a spiral heat exchanger, a working medium in the spiral heat exchanger is water, a required heat source is waste heat from a grate cooler, a rotary kiln and a decomposing furnace of the 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 and decomposition process can be monitored through the window. The working pressure in the hydration decomposing tank is 0.2-0.6 Mpa, and the reaction temperature is 6-15 ℃.
CO 2 The cooling recovery unit device comprises CO 2 Drying device 37, CO 2 Compression device 38, fourth heat exchanger 39, CO 2 A reservoir 40. High-purity CO decomposed out from top of secondary chamber of hydration reaction decomposing tank 2 Through a pressure reducing valve into CO 2 In the drying device 37, CO of the moisture is removed 2 Sequentially through CO 2 The compression device 38 and the fourth heat exchanger 39 enter CO 2 A reservoir 40. The obtained high-purity CO 2 Compressed gas can be used in commercial applications such as industry. The waste heat recovered by the fourth heat exchanger 39 can be used for CO 2 The decomposition process of the hydrate.
The shell of the hydration reaction tank, the solution storage tank and the gas buffer tank are all provided with cooling jackets, circulating cooling water is filled in the cooling jackets, and the purpose of the cooling jackets is to pre-cool the smoke and the aqueous solution which participate in the reaction, so that the stability of the hydration reaction conditions is improved.
The working process comprises the following steps:
the flue gas from the kiln tail chimney is connected with the inlet of the electrostatic precipitator 3 through a pipeline, and the purified flue gas treated by the electrostatic precipitator is subjected to first heat exchangeThe inlet of the device 4 enters the first heat exchanger 4 for cooling, the recovered heat is used for the hydrate decomposition process, the cooled flue gas enters the gas buffer tank 7 again, the flue gas flowing out of the gas buffer tank 7 is boosted to be above the phase equilibrium pressure corresponding to the hydration reaction temperature by the first gas compressor 15, then the flue gas is led into the first gas refrigerator 16 for cooling, the temperature of the flue gas cooled by the first gas refrigerator 16 is about 1-8 ℃, the cooled flue gas passes through the second gas flowmeter 17 and the second gas regulating valve 18, the lower end of the first chamber 20A of the hydration reaction tank is in countercurrent contact with the solution from the solution storage tank 10 for the first hydration reaction, and the generated rich CO is produced 2 The hydrate is captured by a demisting net on the inner wall of the first-stage chamber 20A of the hydration reaction tank and is drained to the bottom of the first-stage chamber 20A of the hydration reaction tank through a diversion trench. At this time CO 2 Hydrate formation pressure drop of 1.5 Mpa, about 75% CO 2 React with water to produce CO 2 A hydrate. The water and the hydrate accelerant are intermittently replenished to the solution storage tank 10 through the water replenishing pipe 8 and the hydrate accelerant replenishing pipe 9 respectively.
The N-enriched water is separated by primary hydration reaction 2 The gas is discharged from a separation gas outlet at the top of the primary chamber of the hydration reaction tank after being subjected to gas-liquid separation by a silk screen, and is introduced into N after cold energy is recovered by a cold energy recovery device 35 2 The storage tank 36 stores and utilizes the same.
CO-rich gas discharged from the bottom of the primary chamber 20A of the hydration reaction tank 2 Hydrate enters the first-stage chamber 23A of the hydration-decomposition tank from a hydrate inlet at the lower part of the first-stage chamber 23A of the hydration-decomposition tank through a third back pressure valve 21, the first-stage chamber 23A of the hydration-decomposition tank is heated by using heat energy in a low-temperature waste heat storage tank 27, so that hydrate slurry entering the first-stage chamber 23A of the hydration-decomposition tank is decomposed, and decomposed gas is discharged from an outlet at the top of the first-stage chamber of the hydration-decomposition tank through a gas-liquid separator at the top of the first-stage chamber 23A of the hydration-decomposition tank. CO in the gas at this time 2 The concentration was about 75%.
The separated gas overflowed from the top of the first stage chamber 23A of the hydration-decomposition tank is cooled by a third heat exchanger 24 and recycled by waste heat, and the heat exchange of the separated gas is directly in the form of fluidAbsorbing and accumulating high-temperature heat energy, introducing cooled separated gas into a second gas compressor 25 for gas pressurization operation, introducing the separated gas cooled by a second gas refrigerator 26 into a second chamber 20B of a hydration reaction tank to be in countercurrent contact with solution sprayed from the top to generate a second hydration reaction, demisting and draining the separated gas to the bottom of a chamber through a demisting net on the side wall of the second chamber, and discharging the separated gas through a hydrate discharge outlet at the bottom of the second chamber. CO in the separated gas of the hydration reaction tank secondary chamber 20B 2 In order to avoid resource waste, the gas separated by the secondary hydration reaction is subjected to gas-liquid separation by a silk screen above a secondary chamber 20B of the hydration reaction tank, then sequentially passes through a separation gas outlet above the secondary chamber, a gas pressure reducing valve 32 and a third gas flowmeter 31, enters into a gas buffer tank 7 from a separation gas inlet at the bottom of the buffer tank, is pressurized by a first gas compressor 15 and is cooled by a first gas cooler 16, and then is subjected to primary hydration reaction again.
The hydrate slurry after the second hydration reaction in the second hydration reaction tank chamber 20B enters the second hydration reaction tank chamber 23B from the hydrate inlet below the second hydration reaction tank chamber 23B through the fourth back pressure valve 22, and is heated by the heat of the external low-temperature waste heat storage tank 27, so that CO in the hydrate is obtained 2 The gas is released and further collected. The low-temperature waste heat storage tank 27 can fully utilize waste heat in the cement production process, and solves the problem of environmental pollution caused by the fact 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 cannot be utilized.
Then synthesizing and decomposing the high-concentration CO through secondary hydration reaction 2 Is delivered to the CO through a gas pressure reducing valve 30 2 In the drying device 37, a water-absorbing drying treatment is performed to form dried CO 2 Gas, CO of dry gas 2 The concentration of (2) reaches more than 99 percent, and then is subjected to CO 2 The compression device 38 performs gas compression treatment, exchanges heat by the fourth heat exchanger 39 and then enters CO 2 As CO in the tank 40 2 And storing the finished product. The CO obtained 2 The finished product can be used for chemical synthesis, dry ice manufacture, food and drug production, oil displacement in oil fields and the like.
Thus, the CO contained in the treated flue gas 2 The amount is extremely low, so that serious pollution to the environment is avoided, the emission reduction requirement of greenhouse gases in the high-emission industry is met, the environment is effectively protected, meanwhile, the used decomposition heat source is derived from waste heat in the cement industrial production process, and the energy utilization efficiency is improved. The carbon dioxide capturing and storing device for cement industry based on the hydrate method has the advantages of simple process and low cost, and can effectively recycle the carbon dioxide in the waste gas after cement production, and remarkably reduce the CO in the atmosphere 2 The discharge amount and can produce economic benefit. The carbon emission reduction historical life of the new stage is favorable for pushing the cement, which is a great cause, to the beautiful future of comprehensive green transformation.
Claims (8)
1. The utility model provides a cement kiln flue gas carbon dioxide entrapment storage system based on hydrate method, includes waste gas pre-treatment unit and the pressurized refrigeration unit that admits air that connects gradually, its characterized in that, the entry of the first class room (20A) of hydration reaction tank is connected to the export of pressurized refrigeration unit that admits air, the entry of the first class room (23A) of hydration decomposition tank is connected to the export of hydration reaction tank first class room (20A) carries out the first-stage separation, the entry of the second class room (20B) of hydration reaction tank is connected to the export of hydration reaction tank first class room (23A) carries out the second-stage hydration reaction, the entry of the second class room (23B) of hydration reaction tank is connected to the export of hydration decomposition tank second class room (23B) carries out the second-stage separation, the exit linkage CO of hydration decomposition tank second class room (23B) 2 A cooling recovery unit; the device also comprises a liquid supply unit for respectively supplying liquid to the first-stage chamber (20A) of the hydration reaction tank and the second-stage chamber (20B) of the hydration reaction tank for hydration reaction;
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 the steel plates are internally filled with heat-insulating cooling materials to keep the temperature in the tank constant;
the first-stage chamber (23A) and the second-stage chamber (23B) of the hydration and decomposition tank are longitudinally arranged in the hydration and decomposition tank, the bottom of the hydration and 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 and decomposition tank, and the low-temperature waste heat storage tank (27) is used for recycling waste heat of a cement kiln grate cooler, a rotary kiln and a decomposition furnace;
the hydrate inlet at the bottom of the first-stage chamber (23A) of the hydration-decomposition tank is connected with the flue gas outlet at the bottom of the first-stage chamber (20A) of the hydration-decomposition tank, and the decomposed gas outlet at the top of the first-stage chamber (23A) of the hydration-decomposition tank is connected with the flue gas inlet at the bottom of the second-stage chamber (20B) of the hydration-decomposition tank through a third heat exchanger (24), a second gas compressor (25) and a second gas refrigerator (26); the hydrate inlet at the bottom of the hydration-decomposition tank secondary chamber (23B) is connected with the flue gas outlet at the bottom of the hydration-decomposition tank secondary chamber (20B); the decomposed gas outlet and CO at the top of the second-stage chamber (23B) of the hydration-decomposition tank 2 Cooling CO of recovery unit 2 The inlet of the drying device is connected.
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 claim 1, wherein the tops of the first-stage chamber (20A) and the second-stage chamber (20B) of the hydration reaction tank are respectively provided with an atomization spraying device which is connected with a liquid supply unit and used for the nucleation reaction of the hydrate; the quenching water device is used for radiating heat generated in the atomizing spraying process and participating in hydration reaction.
3. 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 2, wherein the quenching water device comprises quenching water nozzles respectively arranged in a first chamber (20A) and a second chamber (20B) of the hydration reaction tank, 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 claim 1, wherein a solution inlet for inputting an aqueous solution containing a hydrate accelerator and a separated gas outlet for discharging separated gas after the hydration reaction are respectively arranged at the top of the first-stage chamber (20A) and the top of the second-stage chamber (20B) of the hydration reaction tank; the bottoms of the first-stage chamber (20A) 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 according to claim 1, wherein the top of the primary chamber (23A) of the hydration and decomposition tank and the top of the secondary chamber (23B) of the hydration and decomposition tank are respectively provided with a separating liquid outlet, the two separating liquid outlets share one pipeline, and the pipeline is provided with a heat exchange device and is connected with a solution storage tank (10) of a liquid supply unit through a check valve and a second liquid booster pump.
6. The cement kiln flue gas carbon dioxide capturing and storing system based on the hydrate method according to claim 5, wherein a water supplementing pipe (8) and a hydrate accelerator supplementing 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 separating 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 is divided into two pipelines, and one pipeline is connected with the solution inlet at the upper part of the first stage 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 back pressure valve (34).
7. 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 first chamber (20A) of the hydration reaction tank and the second chamber (20B) of the hydration reaction tank are separated by two layers of pressure-resistant steel plates, and the temperature in the tank is kept constant by filling heat-insulating and cooling materials in the steel plates.
8. The cement kiln flue gas carbon dioxide capturing and storing system based on the hydrate method according to claim 1, wherein the waste gas pretreatment unit comprises an electrostatic precipitator (3) and a first heat exchanger (4) which are connected in sequence.
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