CN107551799B - Dry-method cement kiln flue gas desulfurization and denitrification integrated method - Google Patents
Dry-method cement kiln flue gas desulfurization and denitrification integrated method Download PDFInfo
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- CN107551799B CN107551799B CN201710945712.4A CN201710945712A CN107551799B CN 107551799 B CN107551799 B CN 107551799B CN 201710945712 A CN201710945712 A CN 201710945712A CN 107551799 B CN107551799 B CN 107551799B
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Abstract
A desulfurization and denitrification integrated method for dry-process cement kiln flue gas belongs to the technical field of flue gas pollutant control in the cement industry. Firstly, placing the rice hull ash and the carbide slag at a temperature of 60-105 DEG CDrying for 12-24 h; then uniformly mixing the rice hull ash and the carbide slag according to different volume ratios (1: 1-9: 1); finally, carrying out SO treatment on the rice hull ash and the carbide slag at the temperature of 800-900 ℃ and the oxygen concentration of 1-5%2And simultaneous removal of NOx. The carbide slag can be used as a cement raw material to be proportioned, and the oxide ash in the rice husk ash can also be used as a cement component, so that the performance of the cement is not influenced. And Ca in the carbide slag can promote the process of reducing nitrogen oxide by carbon while desulfurizing, and the rice husk ash provides larger reaction space for desulfurization and denitrification while utilizing C for denitrification, so that the reaction is more sufficient. The invention has simple process, low cost of the adsorption material and high desulfurization and denitration efficiency.
Description
Technical Field
The invention belongs to the technical field of control of smoke pollutants in cement industry, and particularly relates to a method for realizing integration of desulfurization and denitrification in a cement kiln decomposing furnace by using a carbide slag/rice hull ash composite additive.
Background
SO2And NOx is a main atmospheric pollutant in tail gas of a cement industrial kiln, is a main reason for causing acid rain, and can cause a series of environmental problems such as haze, photochemical pollution, greenhouse effect and the like. With the increasing environmental protection requirements, the emission standard of atmospheric pollutants in the cement industry (GB 4915 and 2013) stipulates that: general regional SO2And NOx emission limit of 200mg/m, respectively3、400mg/m3SO of key area2And NOx emission limit of 100mg/m, respectively3、320mg/m3Strict control of SO is required2And NOx emissions. Therefore, the effective reduction of SO in the cement industry is found2And NOx emissions, are critical.
At present, SO is generally treated in the cement industry2And NOx are removed separately. The desulfurization in the cement industry at present mainly utilizes limestone in raw materials to absorb SO2And additional SO including dry method, wet method, semi-dry method, composite desulfurization technology and the like2Emission reduction techniques, however existingThe desulfurization technology has the problems of low desulfurization efficiency, large equipment investment or high operation cost and the like. On the other hand, the current main denitration methods are Selective Catalytic Reduction (SCR) technology and selective non-catalytic reduction (SNCR) technology, both of which require ammonia gas or urea as a reducing agent, so additional ammonia (urea) storage and ammonia (urea) injection devices are required, and ammonia slip phenomenon occurs, which causes secondary pollution. Most of the currently adopted integrated desulfurization and denitrification technologies are the combination of two manners of desulfurization and denitrification, namely SO2And NOx, respectively. The combined desulfurization and denitrification technology has the problems of high fixed investment, complex flow, complex operation, high operation and maintenance cost and the like. The integrated technology for flue gas desulfurization and denitration can realize desulfurization and denitration simultaneously in the same system, shortens the flow, simplifies equipment, occupies small area, has low capital investment, convenient operation and management, low production cost and the like, and becomes a leading research direction in the field of atmospheric pollution control.
Activated carbon in O2Adsorbing SO in the flue gas in the presence of water vapor2After sulfuric acid is generated, the sulfuric acid is heated or washed and regenerated for recycling. Adding NH into an active carbon absorption desulfurization system3NOx can be removed simultaneously. The activated carbon method has attracted extensive attention because of its advantages of being able to remove sulfur dioxide and nitrogen oxide in flue gas, and the adsorbent being able to regenerate. But the market cost is high, and the requirement of large-scale industrial use is difficult to meet. The removal reaction temperature is low, the optimal reaction temperature is 100-200 ℃, the method is not suitable for the cement industry, the denitration effect can be achieved only by adding ammonia gas, and the process is complex. Therefore, the search for an adsorbent with low cost and good adsorption effect has been an effort of researchers in various countries. Carbide slag, which is an industrial waste that is difficult to treat, causes serious pollution to the surrounding environment. The carbide slag is used as a calcium-based desulfurizer for flue gas desulfurization instead of limestone, so that a large amount of exploitation of the limestone is reduced, the carbide slag waste can be utilized, and the problem of environmental pollution is solved. The existing research shows that the reaction activity of the carbide slag in the desulfurization reaction is superior to that of limestone, and moisture escapes when the carbide slag is heated and decomposed to enable generated CaO to have more pores, which is beneficial to gasThe solid-phase reaction is carried out, and the desulfurization effect is good. The carbide slag is suitable for combustion at about 900 ℃, the sulfur fixation efficiency is high, and the temperature accords with the temperature of a cement kiln decomposing furnace. The rice hull ash is a main byproduct after the combustion of rice hulls, is rich in amorphous silica and carbon, and is also a main garbage generated in agriculture. The catalyst has the advantages of low price, large quantity and high specific surface area, so the catalyst has high reaction activity and certain utilization value. The use of the rice hull ash not only can significantly improve the development of industrialization, but also can protect the environment from being polluted. The carbide slag and the rice hull ash can achieve high economic benefit with low cost, and are high-quality raw materials for realizing integration of desulfurization and denitrification of the flue gas of the cement kiln.
Disclosure of Invention
The invention aims to provide a method for realizing integration of desulfurization and denitrification in a cement kiln decomposing furnace by using a carbide slag/rice hull ash composite additive. Can effectively and simultaneously remove SO2And NOx. The preparation is simple to prepare, convenient to operate, capable of simultaneously performing desulfurization and denitrification and good in removal effect.
The invention adopts the following specific technical scheme:
the method for integrating desulfurization and denitrification of the flue gas of the dry-process cement kiln is characterized by comprising the following steps of: firstly, drying the rice hull ash and the carbide slag at the temperature of 60-105 ℃ for 12-24 h; then uniformly mixing the dried rice husk ash and the carbide slag according to the volume ratio of the rice husk ash to the carbide slag of 1: 1-9: 1; finally, the volume percentage concentration of oxygen is 1 to 5 percent, 1000ppmNO and 2000ppmSO2、N2Performing SO treatment on the rice hull ash and the carbide slag under the conditions that the total gas flow rate is 900ml/min and the temperature is 800-900 ℃ as balance gas2And simultaneous removal of NOx.
Further, SO is carried out when the volume ratio of the rice hull ash to the carbide slag is 3:1, the oxygen volume percentage concentration is 1-5%, and the temperature is 900 DEG C2And simultaneous removal of NOx.
The carbide slag can be used as a cement raw material to be proportioned, and the oxide ash in the rice husk ash can also be used as a cement component, so that the performance of the cement is not influenced.
Wherein, the principle of carbide slag desulfurization:
Ca(OH)2→CaO+H2O (1)
CaO+SO2→1/2O2+CaSO4(2)
CaCO3→CaO+CO2(3)
CaO+SO2→CaSO3(4)
the carbon material denitration principle:
C+NO→CO+1/2N2(5)
C+2NO→CO2+N2(6)
CO+NO→CO2+1/2N2(7)
the invention has the following effects:
(1) utilize carbide slag high-efficient absorption SO2At the same time of gas, the rice husk ash with high specific surface area can provide more space and places for reaction, thereby increasing SO2The absorption rate of (a); when carbon in the rice hull ash is used for reducing nitrogen oxides, as research shows that Ca can promote C-NO reaction and CaO is considered as a high-activity substance for catalyzing the C-NO reaction, CaO serving as a main component of the carbide slag plays a certain catalytic role in reducing the nitrogen oxides; in the system, the desulfurization and denitration reactions are mutually promoted, so that a good removal effect can be achieved.
(2) When the mixed material of the carbide slag and the rice hull ash is added into the cement kiln decomposing furnace, the existing cement kiln does not need to be modified, the investment cost is low, and the operation is simple. Carbide slag and rice husk ash are waste residues, the problem of treatment of the waste residues is solved while desulfurization and denitrification are performed, and the environmental benefit is remarkable.
(3) The addition of the carbide slag and the rice hull ash does not influence the composition of the cement raw materials, can ensure the normal operation of the cement kiln, and does not have adverse effect on the performance of cement clinker.
Detailed Description
The present invention will be further illustrated with reference to the following examples, but the present invention is not limited to the following examples.
Firstly, drying the rice hull ash and the carbide slag at the temperature of 60-105 ℃ for 12-24 h; both the shell ash and the carbide slag of the following examples were dried.
Example 1
Under the smoke condition of 1000ppmNO and 2000ppmSO2、1％O2，N2The total gas flow rate is 900ml/min, the temperature is 800 ℃, the rice hull ash and the carbide slag are uniformly mixed according to the volume ratio of 9:1 and then are added into a tubular furnace with the diameter of 3cm, the denitration rate reaches 63.7 percent, and the desulfurization rate reaches 93.7 percent.
Example 2
Under the smoke condition of 1000ppmNO and 2000ppmSO2、1％O2，N2The total gas flow rate is 900ml/min, when the temperature is 900 ℃, the rice hull ash and the carbide slag are uniformly mixed according to the volume ratio of 9:1 and then are added into a tubular furnace with the diameter of 3cm, the denitration rate reaches 63.2 percent, and the desulfurization rate reaches 95.4 percent.
Example 3
Under the smoke condition of 1000ppmNO and 2000ppmSO2、1％O2，N2The total gas flow rate is 900ml/min, the temperature is 800 ℃, the rice hull ash and the carbide slag are uniformly mixed according to the volume ratio of 6:1 and then are added into a tubular furnace with the diameter of 3cm, the denitration rate reaches 60.2 percent, and the desulfurization rate reaches 94.1 percent.
Example 4
Under the smoke condition of 1000ppmNO and 2000ppmSO2、1％O2，N2The total gas flow rate is 900ml/min, when the temperature is 900 ℃, the rice hull ash and the carbide slag are uniformly mixed according to the volume ratio of 6:1 and then are added into a tubular furnace with the diameter of 3cm, the denitration rate reaches 60.2 percent, and the desulfurization rate reaches 96.2 percent.
Example 5
Under the smoke condition of 1000ppmNO and 2000ppmSO2、1％O2，N2The total gas flow rate is 900ml/min, the temperature is 800 ℃, the rice hull ash and the carbide slag are uniformly mixed according to the volume ratio of 3:1 and then are added into a tubular furnace with the diameter of 3cm, the denitration rate reaches 78.4%, and the desulfurization rate reaches 97.5%.
Example 6
Under the smoke condition of 1000ppmNO and 2000ppmSO2、1％O2，N2The total gas flow rate is 900ml/min, when the temperature is 900 ℃, the rice hull ash and the carbide slag are uniformly mixed according to the volume ratio of 3:1 and then are added into a tubular furnace with the diameter of 3cm, the denitration rate reaches 79.3 percent, and the desulfurization rate reaches 98.7 percent.
Example 7
Under the smoke condition of 1000ppmNO and 2000ppmSO2、1％O2，N2The total gas flow rate is 900ml/min, the temperature is 800 ℃, the rice hull ash and the carbide slag are uniformly mixed according to the volume ratio of 1:1 and then are added into a tubular furnace with the diameter of 3cm, the denitration rate reaches 62.8 percent, and the desulfurization rate reaches 97.1 percent.
Example 8
Under the smoke condition of 1000ppmNO and 2000ppmSO2、1％O2，N2The total gas flow rate is 900ml/min, when the temperature is 900 ℃, the rice hull ash and the carbide slag are uniformly mixed according to the volume ratio of 1:1 and then are added into a tubular furnace with the diameter of 3cm, the denitration rate reaches 60.2 percent, and the desulfurization rate reaches 98.3 percent.
Example 9
Under the smoke condition of 1000ppmNO and 2000ppmSO2、2％O2，N2The total gas flow rate is 900ml/min, when the temperature is 900 ℃, the rice hull ash and the carbide slag are uniformly mixed according to the volume ratio of 3:1 and then are added into a tubular furnace with the diameter of 3cm, the denitration rate reaches 75.2 percent, and the desulfurization rate reaches 97.3 percent.
Example 10
Under the smoke condition of 1000ppmNO and 2000ppmSO2、3％O2，N2The total gas flow rate is 900ml/min, when the temperature is 900 ℃, the rice hull ash and the carbide slag are uniformly mixed according to the volume ratio of 3:1 and then are added into a tubular furnace with the diameter of 3cm, the denitration rate reaches 73.6 percent, and the desulfurization rate reaches 97.8 percent.
Example 11
Under the smoke condition of 1000ppmNO and 2000ppmSO2、4％O2，N2The total gas flow rate is 900ml/min, when the temperature is 900 ℃, the rice hull ash and the carbide slag are uniformly mixed according to the volume ratio of 3:1 and then are added into a tubular furnace with the diameter of 3cm, the denitration rate reaches 73.4 percent, and the desulfurization rate reaches 98.2 percent.
Example 12
Under the smoke condition of 1000ppmNO and 2000ppmSO2、5％O2，N2The total gas flow rate is 900ml/min, when the temperature is 900 ℃, the rice hull ash and the carbide slag are uniformly mixed according to the volume ratio of 3:1 and then are added into a tubular furnace with the diameter of 3cm, the denitration rate reaches 71.7 percent, and the desulfurization rate reaches 98.6 percent.
TABLE 1 desulfurization and denitrification rates of examples
Claims (2)
1. The method for integrating desulfurization and denitrification of the flue gas of the dry-process cement kiln is characterized by comprising the following steps of: firstly, drying the rice hull ash and the carbide slag at the temperature of 60-105 ℃ for 12-24 h; then uniformly mixing the dried rice husk ash and the carbide slag according to the volume ratio of the rice husk ash to the carbide slag of 1: 1-9: 1; finally, the volume percentage concentration of the oxygen is 1-5%, 1000ppmNO and 2000ppmSO2、N2Adding the mixed material of the carbide slag and the rice husk ash into a cement kiln decomposing furnace under the conditions that the total gas flow rate is 900ml/min and the temperature is 800-900 ℃ as balance gas, and carrying out SO (sulfur oxide) treatment by using the rice husk ash and the carbide slag2And simultaneous removal of NOx.
2. The method for integrating desulfurization and denitrification of the flue gas of the dry-process cement kiln according to claim 1, which is characterized in that: performing SO treatment at 900 ℃ when the volume ratio of the dried rice hull ash to the carbide slag is 3:1, the oxygen volume percentage concentration is 1-5%2And simultaneous removal of NOx.
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| CN108654315B (en) * | 2018-05-08 | 2020-11-27 | 北京工业大学 | Preparation method of flue gas desulfurization and denitrification absorbent of rice hull ash/carbide slag system |
| CN109603505A (en) * | 2019-01-25 | 2019-04-12 | 广东万引科技发展有限公司 | A kind of method of denitration of the dry-process cement rotary kiln flue gas with biomass bamboo charcoal |
| CN111606400A (en) * | 2020-04-24 | 2020-09-01 | 北京中冶设备研究设计总院有限公司 | Low-cost desulfurization wastewater pretreatment method |
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| CN101559318B (en) * | 2009-05-25 | 2013-10-30 | 天津城市建设学院 | Thermal carbon composite denitration method for coal-fired boiler |
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