A method for treating decarbonized flue gas after carbon capture by chemical absorption in the cement industry
By using oxygen-enriched combustion technology to treat the decarbonized flue gas from the chemical absorption method, the problem of limited organic pollutant emissions has been solved, achieving the harmless disposal of organic pollutants and efficient cooling of cement clinker, thus improving cement quality.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- BEIJING BUILDING MATERIALS ACADEMY OF SCI RES
- Filing Date
- 2022-11-07
- Publication Date
- 2026-05-22
Smart Images
Figure CN115823595B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of cement technology, specifically to a method for treating decarbonized flue gas after carbon capture by chemical absorption in the cement industry, and more particularly to a method for the resource utilization and harmless disposal of decarbonized flue gas after carbon capture by chemical absorption in the cement industry. Background Technology
[0002] Currently, how to deeply integrate carbon reduction technologies with the cement industry and innovate these technologies has become a key focus and research hotspot in the cement industry. Therefore, many carbon capture technologies have been widely applied, such as absorption and adsorption methods. Chemical absorption is the most mature method among absorption methods, typically using amine organic compounds as absorbents to absorb carbon dioxide from flue gas, which is then desorbed in a desorption tower. However, during the absorption-desorption process, the volatiles and degradation products of the amine absorbents enter the decarbonized flue gas, forming organic pollutants. Therefore, the decarbonized flue gas cannot be directly emitted, and current methods still cannot achieve complete harmless treatment of organic pollutants.
[0003] Therefore, this invention is proposed. Summary of the Invention
[0004] This invention addresses the characteristics of existing cement processes and chemical absorption carbon capture processes by providing a method for treating decarbonized flue gas after chemical absorption carbon capture in the cement industry. This method overcomes the limitations of existing technologies where decarbonized flue gas contains organic pollutants and thus has restricted emissions. It achieves deep integration of carbon capture, oxygen-enriched combustion, and cement processes, enabling the decarbonized flue gas to achieve full resource utilization and complete harmless disposal.
[0005] This invention provides a method for treating decarbonized flue gas after carbon capture by chemical absorption in the cement industry, comprising: performing oxygen-enriched gas containing organic matter obtained by treating the decarbonized flue gas through a steam condensation process and a nitrogen separation process, and then performing oxygen-enriched combustion.
[0006] In industrial production, gases with an oxygen content greater than 21% are generally called oxygen-enriched gases. Oxygen-enriched combustion (OEC) refers to the chemical reaction process that occurs when the oxygen concentration in the oxidizer used for combustion is higher than the oxygen concentration in the air. Based on the type of oxidizer, OEC can be divided into partial OEC and overall OEC; based on the oxygen concentration, it can be divided into low-concentration (21%~30%), high-concentration (30%~90%), full oxygen (90%~95%), and even pure oxygen (95%~100%) combustion. In the cement industry, compared to air-supplyed combustion technology, OEC has significant advantages: reduced exhaust gas volume, reduced heat loss, increased flame temperature, enhanced flame heat transfer capacity, and increased CO2 concentration in flue gas, which is beneficial for carbon capture.
[0007] Because the flue gas after decarbonization by chemical absorption contains organic pollutants, which are newly added pollutants and are not suitable for direct emission (some local standards are strict and cannot add new pollutants), these organic pollutants need to be thoroughly and harmlessly treated. This invention is the first to apply oxygen-enriched combustion technology to the treatment of decarbonized flue gas after carbon capture by chemical absorption. In particular, the oxygen-enriched gas generated from the decarbonized flue gas through processes such as water-gas separation and nitrogen separation, due to its special composition, can achieve the complete harmless treatment of pollutants during oxygen-enriched combustion.
[0008] According to the method for treating decarbonized flue gas after carbon capture by chemical absorption in the cement industry provided by the present invention, the oxygen-enriched gas further includes: blowing the oxygen-enriched gas into a grate cooler section for oxygen-enriched combustion, wherein the oxygen-enriched gas exchanges physical heat with the cement clinker when it is blown into the grate cooler to cool the cement clinker to below 1250°C.
[0009] Preferably, the temperature of the oxygen-enriched gas introduced into the first stage of the grate cooler is not higher than the ambient temperature, such as not higher than 25°C.
[0010] More preferably, the amount of oxygen-enriched gas introduced accounts for 5% to 100% of the total air volume of the grate cooler. The present invention has found that introducing the oxygen-enriched gas into the grate cooler for cooling cement clinker and performing oxygen-enriched combustion can not only achieve the complete harmless treatment of pollutants, but also use the low-temperature oxygen-enriched gas to help the cement clinker cool rapidly. This not only avoids the addition of new equipment, but also achieves a good cooling effect for clinker.
[0011] More preferably, the amount of oxygen-enriched gas introduced accounts for 60% to 100% of the total air volume of the grate cooler. When the amount of oxygen-enriched gas introduced is set within this range, the cooling efficiency of cement clinker is greatly improved, and rapid cooling conditions can be achieved. At this time, tricalcium silicate can exist in a metastable state at room temperature, thereby avoiding the decomposition of tricalcium silicate into dicalcium silicate, thus improving the quality of cement.
[0012] According to the method for treating decarbonized flue gas after carbon capture by chemical absorption in the cement industry provided by the present invention, the composition of the oxygen-enriched gas is: 0.1%~1.5% water vapor, 12%~70% nitrogen, 21.1%~85% oxygen, 2%~8% carbon dioxide, and the balance being organic pollutants.
[0013] The decarbonized flue gas of the present invention mainly contains 6% to 15% water vapor, 75% to 85% nitrogen, 6% to 14% oxygen, 0.4% to 5% carbon dioxide and a small amount of organic pollutants, wherein the organic pollutants include amine carbon dioxide absorbents and their degradation products, and may contain other organic pollutants from kiln tail flue gas.
[0014] According to the method for treating decarbonized flue gas after carbon capture by chemical absorption in the cement industry provided by the present invention, the temperature of the decarbonized flue gas is 30~45℃.
[0015] According to the method for treating decarbonized flue gas after carbon capture by chemical absorption in the cement industry provided by the present invention, the oxygen-enriched combustion has a greater than 99.99% removal rate of organic pollutants in the oxygen-enriched gas, preferably 99.9999%.
[0016] According to the method for treating decarbonized flue gas after carbon capture by chemical absorption in the cement industry provided by the present invention, the water vapor condensation process makes the removal rate of water vapor in the decarbonized flue gas greater than 95%.
[0017] The steam condensation process involves using heat exchange to lower the temperature of the decarbonized flue gas to below 20°C, condensing the water vapor in the flue gas. At this stage, a very small amount of water-soluble organic matter may remain, but this condensate can be properly treated after being channeled into the cement plant's wastewater treatment facilities. Furthermore, this invention has found that when the water vapor removal rate in the decarbonized flue gas is greater than 95% during the steam condensation process, it is more conducive to oxygen-enriched combustion.
[0018] According to the method for treating decarbonized flue gas after carbon capture by chemical absorption in the cement industry provided by the present invention, the nitrogen separation process makes the nitrogen removal rate in the decarbonized flue gas greater than 55%.
[0019] Since nitrogen is the main component of the decarbonized flue gas, the nitrogen removal rate has a significant impact on the oxygen concentration in the oxygen-enriched gas. This invention has found that when the nitrogen removal rate in the decarbonized flue gas is greater than 55% during the nitrogen separation process, it is more conducive to oxygen-enriched combustion.
[0020] According to the method for treating decarbonized flue gas after carbon capture by chemical absorption in the cement industry provided by the present invention, the nitrogen-rich gas obtained from the nitrogen separation process is subjected to a nitrogen purification process.
[0021] Preferably, the non-target gas generated in the nitrogen purification process is recycled back into the nitrogen separation process and mixed with the dehydrated flue gas for re-purification. After the nitrogen purification process, the nitrogen concentration obtained is 95%~99.9999%.
[0022] According to the method for treating decarbonized flue gas after carbon capture by chemical absorption in the cement industry provided by the present invention, the raw gas for carbon capture includes kiln tail flue gas from co-processing waste (including hazardous waste).
[0023] Conventional cement kiln production processes primarily focus on cement production, generating pollutants mainly including nitrogen oxides, sulfur dioxide, carbon dioxide, and dust. Compared to conventional cement kiln production processes, cement kiln co-processing technology has matured over the past decade or so, capable of co-processing municipal solid waste, sludge, soil, and hazardous waste. Due to the complex sources of the treated materials, the composition of the pollutants is also more complex. This invention is applicable not only to conventional cement production processes but also to cement kiln co-processing technologies.
[0024] This invention provides a method for treating decarbonized flue gas after carbon capture by chemical absorption in the cement industry. By performing oxygen-enriched combustion of oxygen-enriched gas containing organic pollutants from the original decarbonized flue gas, a deep coupling of complete harmless treatment of organic pollutants and oxygen-enriched combustion can be achieved.
[0025] This invention provides a method for treating decarbonized flue gas after carbon capture by chemical absorption in the cement industry. The oxygen-enriched gas is blown into the grate cooler in the cement kiln system for oxygen-enriched combustion. This method not only achieves complete and harmless treatment of organic pollutants but also cools cement clinker, and the cooling effect is good.
[0026] This invention provides a method for treating decarbonized flue gas after chemical absorption carbon capture in the cement industry. First, a condensation method is used to condense the moisture in the decarbonized flue gas from water vapor to liquid. Then, nitrogen separation is performed, and the separated nitrogen is further concentrated and purified to prepare high-purity nitrogen products. After moisture removal and nitrogen separation, the oxygen concentration in the decarbonized flue gas is increased to an oxygen-enriched state. Oxygen-enriched gas containing organic pollutants from the original decarbonized flue gas is then blown into the first stage of the grate cooler in the cement kiln system. This achieves a deep coupling of cement clinker cooling, complete harmless treatment of organic pollutants, and oxygen-enriched combustion. This method not only enables the resource utilization and harmless treatment of decarbonized flue gas after chemical absorption carbon capture in the cement industry but also achieves deep integration of carbon capture, oxygen-enriched combustion, and cement processes, providing a solution to the emission restrictions caused by organic pollutants in decarbonized flue gas. Attached Figure Description
[0027] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.
[0028] Figure 1 This is a schematic flowchart of the method for treating decarbonized flue gas after carbon capture by chemical absorption in the cement industry provided by the present invention. Detailed Implementation
[0029] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.
[0030] Where specific techniques or conditions are not specified in the examples, they shall be performed in accordance with the techniques or conditions described in the literature in this field, or in accordance with the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased through legitimate channels.
[0031] The following is combined Figure 1 This invention describes a method for treating decarbonized flue gas after carbon capture using chemical absorption in the cement industry.
[0032] Example 1
[0033] A method for treating decarbonized flue gas after carbon capture using chemical absorption in the cement industry, such as... Figure 1 As shown, the specific process is as follows:
[0034] Carbon capture of kiln tail gas in the cement industry is carried out by chemical absorption to obtain decarbonized flue gas; the decarbonized flue gas contains 10% water vapor, 80% nitrogen, 9% oxygen, 0.8% carbon dioxide and a small amount of organic pollutants.
[0035] The decarbonized flue gas at a temperature of 35℃ is first condensed and recovered from water vapor at a temperature of 12℃, with a water vapor condensation rate of 98%, resulting in condensate and dewatered flue gas. The condensate is then discharged into the wastewater treatment facility in the cement plant area.
[0036] The dehydrated flue gas is then subjected to nitrogen pressure swing adsorption (PSA): using carbon molecular sieves as the adsorbent, the flue gas is held at 1.5 MPa for 5 minutes to separate nitrogen from the dehydrated flue gas, achieving a separation rate of 94%. The separated nitrogen is then desorbed and further purified (e.g., using PSA) to remove some non-target gas components, increasing the nitrogen purity to 99.99%. This allows for the further preparation of high-purity nitrogen products (e.g., 99.9996% purity). The resulting non-target gas components are recycled back into the nitrogen separation process and mixed with the dehydrated flue gas for re-purification. The decarbonized flue gas, after steam condensation, nitrogen separation, and nitrogen purification, yields an oxygen-enriched gas with an oxygen concentration of not less than 60%. The gas composition of this oxygen-enriched gas is shown in Table 1.
[0037] Finally, oxygen-enriched gas is blown into the first stage of the grate cooler to complete oxygen-enriched combustion, harmless treatment of organic pollutants, and cooling of cement clinker. The amount of oxygen-enriched gas blown into the grate cooler accounts for 60% of the total air volume of the grate cooler. When the oxygen-enriched gas is blown into the grate cooler, it exchanges physical heat with the cement clinker to cool the cement clinker to below 1250°C, thereby achieving harmless treatment of organic pollutants. The incineration removal rate of organic pollutants is greater than 99.99%.
[0038] Example 2
[0039] A method for treating decarbonized flue gas after carbon capture using chemical absorption in the cement industry, the specific process of which is as follows:
[0040] Carbon capture of kiln tail gas in the cement industry is carried out by chemical absorption to obtain decarbonized flue gas; the decarbonized flue gas contains 10% water vapor, 80% nitrogen, 9% oxygen, 0.8% carbon dioxide and a small amount of organic pollutants.
[0041] The decarbonized flue gas at 30℃ is first condensed and recovered from water vapor at 12℃, with a water vapor condensation rate of 98%, resulting in condensate and dewatered flue gas. The condensate is then discharged into the wastewater treatment facility in the cement plant area.
[0042] The dehydrated flue gas was then subjected to nitrogen pressure swing adsorption separation using carbon molecular sieve as the adsorbent. At a pressure of 0.5 MPa, the flue gas was held for 3 minutes to separate nitrogen from the dehydrated flue gas, achieving a separation rate of 86%. The separated nitrogen was then desorbed and further purified to remove some non-target gas components, increasing the nitrogen purity to 99.99%. This allows for the further preparation of high-purity nitrogen products (such as 99.9999% purity). The generated non-target gas components were recycled back into the nitrogen separation process and mixed with the dehydrated flue gas for re-purification. After steam condensation, nitrogen separation, and nitrogen purification, the oxygen concentration in the oxygen-enriched gas was no less than 42.06%, as shown in Table 1.
[0043] Finally, oxygen-enriched gas is blown into the first stage of the grate cooler to complete oxygen-enriched combustion, harmless treatment of organic pollutants, and cooling of cement clinker. The amount of oxygen-enriched gas blown into the grate cooler accounts for 80% of the total air volume of the grate cooler. When the oxygen-enriched gas is blown into the grate cooler, it exchanges physical heat with the cement clinker to cool the cement clinker to below 1250°C, thereby achieving harmless treatment of organic pollutants. The incineration removal rate of organic pollutants is greater than 99.99%.
[0044] Example 3
[0045] A method for treating decarbonized flue gas after carbon capture using chemical absorption in the cement industry, the specific process of which is as follows:
[0046] Carbon capture of kiln tail gas in the cement industry is carried out by chemical absorption to obtain decarbonized flue gas; the decarbonized flue gas contains 10% water vapor, 80% nitrogen, 9% oxygen, 0.8% carbon dioxide and a small amount of organic pollutants.
[0047] The decarbonized flue gas at a temperature of 45℃ is first condensed and recovered from water vapor at a temperature of 15℃, with a water vapor condensation rate of 96%, resulting in condensate and dewatered flue gas. The condensate is then discharged into the wastewater treatment facility in the cement plant area.
[0048] Then, mature and generalized nitrogen separation technology is used to separate and remove nitrogen, achieving a separation rate of 72%. The separated nitrogen is then desorbed and further purified to remove some non-target gas components, increasing the nitrogen purity to 99.99%. This allows for the further production of high-purity nitrogen products (such as 99.999% pure nitrogen). The generated non-target gas components are recycled back into the nitrogen separation process. The original decarbonized flue gas, after undergoing steam condensation, nitrogen separation, and nitrogen purification processes, is mixed with the dehydrated flue gas for further purification. The oxygen concentration in the oxygen-enriched gas is no less than 27.44%, and the gas composition of this oxygen-enriched gas is shown in Table 1.
[0049] Finally, oxygen-enriched gas is blown into the first stage of the grate cooler to complete oxygen-enriched combustion, harmless treatment of organic pollutants, and cooling of cement clinker. The amount of oxygen-enriched gas blown into the grate cooler accounts for 100% of the total air volume of the grate cooler. When the oxygen-enriched gas is blown into the grate cooler, it exchanges physical heat with the cement clinker to cool the cement clinker to below 1250°C, thereby achieving harmless treatment of organic pollutants. The incineration removal rate of organic pollutants is greater than 99.99%.
[0050] Table 1. Target gas component concentrations in different embodiments
[0051]
[0052] Note: The above contents refer to the concentration of a certain substance in oxygen-enriched gas.
[0053] In the above embodiments 1 to 3, no gas is discharged during oxygen-enriched combustion, and the generated flue gas is combined with the original flue gas. Since the carbon dioxide, water and nitrogen oxides produced by the complete combustion of organic matter in the oxygen-enriched gas are very low, they have almost no impact on the gas composition produced by the original process.
[0054] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit of the technical solutions of the embodiments of the present invention.
Claims
1. A method for treating decarbonized flue gas after carbon capture using chemical absorption in the cement industry, characterized in that, include: The decarbonized flue gas is treated by a steam condensation process and a nitrogen separation process to obtain an oxygen-enriched gas containing organic matter, which is then blown into a grate cooler for oxygen-enriched combustion. During the blowing of the oxygen-enriched gas into the grate cooler, it undergoes physical heat exchange with the cement clinker to cool the cement clinker to below 1250°C. The oxygen-enriched gas consists of: 0.1% to 1.5% water vapor, 12% to 70% nitrogen, 21.1% to 85% oxygen, 2% to 8% carbon dioxide, and the remainder being organic pollutants.
2. The method for treating decarbonized flue gas after chemical absorption carbon capture in the cement industry according to claim 1, characterized in that, The amount of oxygen-enriched gas introduced accounts for 5% to 100% of the total air volume of the grate cooler.
3. The method for treating decarbonized flue gas after carbon capture by chemical absorption in the cement industry according to claim 1 or 2, characterized in that, The temperature of the decarbonized flue gas is 30~45℃.
4. The method for treating decarbonized flue gas after chemical absorption carbon capture in the cement industry according to any one of claims 1 to 3, characterized in that, The oxygen-enriched combustion process achieves a greater than 99.99% removal rate of organic pollutants from the oxygen-enriched gas.
5. The method for treating decarbonized flue gas after chemical absorption carbon capture in the cement industry according to any one of claims 1 to 4, characterized in that, The water vapor condensation process enables the removal rate of water vapor in the decarbonized flue gas to be greater than 95%.
6. The method for treating decarbonized flue gas after chemical absorption carbon capture in the cement industry according to any one of claims 1 to 5, characterized in that, The nitrogen separation process results in a nitrogen removal rate of more than 55% in the decarbonized flue gas.
7. The method for treating decarbonized flue gas after chemical absorption carbon capture in the cement industry according to claim 6, characterized in that, The nitrogen-rich gas obtained from the nitrogen separation process is then purified by a nitrogen purification process.
8. The method for treating decarbonized flue gas after carbon capture by chemical absorption in the cement industry according to claim 7, characterized in that, The non-target gas generated in the nitrogen purification process is recycled back into the nitrogen separation process and mixed with the dewatered flue gas for re-purification.
9. The method for treating decarbonized flue gas after chemical absorption carbon capture in the cement industry according to claim 1, characterized in that, The carbon capture feed gas includes kiln tail gas used for co-processing waste.