1. Background
In September 2020, the President of the People's Republic of China solemnly declared at the general debate of the 75th General Assembly of the United Nations that China's carbon dioxide emissions would strive to reach the peak by 2030 and strive to achieve carbon neutrality by 2060. The above schedule of carbon peaking and carbon neutralization is also known as the "double carbon" goal. The goal of "
double carbon" will not only solve the problem of ecological and environmental protection, but also trigger a broad and profound economic and social change. For the vast number of industrial enterprises, carbon emission reduction inaction will face the problem of survival and development. In the first half of
this year, the economic recovery was not as good as expected, which was reflected in the lack of confidence in consumption and investment, the performance of the cement industry was not optimistic, and the volume and price of cement fell in the first half of this year. Expert analysis shows that China's economic growth model is switching from "capital" driven to "operation" driven. Cement enterprises are transforming from extensive to refined. Economists divide the past of China's economic development into the first half, the present and the future into the second half. The first half is the 40 years from 1979 to 2019. The core problem to be solved is the primitive accumulation of capital. Through the accumulation of capital, two major tasks have been accomplished: one is to use reinforced concrete to do a good job in infrastructure and housing, and the other is to launch various Internet platforms to improve the efficiency of social operation. In this process, the cement industry has experienced the development process of shaft kiln, wet kiln, dry hollow kiln, preheater kiln and decomposition kiln outside the kiln from backward technology to world leading, from shortage of supply to overcapacity. In the past 40 years, the cement industry has benefited a lot from the rapid development of cement technology. The second half is driven by the operation, through the filling of "product + content", so that the society has flesh and blood, only the operation of products and content can have a way out! In the process of China's economic transformation, our cement enterprises should change their concepts, keep up with changes, adapt to new development needs, and do a good job in operation. 2. Environmental protection status of cement enterprises Analysis of pollution control of cement plants: The main pollution sources of cement plants are dust, flue gas, noise and waste water, which can be discharged up to the standard after environmental protection treatment. If the discharge is not up to the standard, the production will be suspended and the fine will be imposed, which is mandatory. The main problems facing the cement industry are how to formulate pollutant discharge indicators and how to select pollution control technologies with high cost performance and low cost. Smoke and dust control in Europe is differentiated, with strict requirements in sensitive areas and loose requirements in insensitive areas. costs of enterprises, especially in the case of a depressed cement market, the pressure on enterprises will be greater. Therefore, from the perspective of scientific development, the emission of smoke and dust from cement plants is not necessarily the lower the better. Denitrification is imperative . According to the NOx emission coefficient of 1.5-1 per ton of clinker, the government has issued relevant policies and standards. It is clearly required that NOx emissions should not be produced if they do not meet the standards. Cement enterprises urgently need to find the best way to reduce the emission of nitrogen oxides. 3. Denitrification technology At present, the emission standard implemented by the domestic cement industry is the Emission Standard of Air Pollutants for Cement Industry (GB 4915-2013). For example, the local standard issued by Zhejiang Province requires that the NOx emission concentration of cement kiln flue gas should be less than 50 mg/Nm3 by 2025. The four provinces in southwest China have also issued relevant policies this year. In addition, the Technical Guidelines for Emergency Emission Reduction in Key Industries of Heavily Polluted Weather issued by the Ministry of Environmental Protection require that cement production adopt SNCR, SCR and other technologies to achieve ultra-low emissions, and that the consumption of ammonia water per ton of cement clinker is less than 4 kg, so as to be recognized as A-level enterprises, enjoy corresponding policy support, subsidize 50%, and reward operation. China's cement industry began to promote non-catalytic reduction technology (SNCR) in 2007. The denitration efficiency of SNCR technology can be as high as 60% (there is a new breakthrough at present). During this period, the use of staged combustion technology was also studied, that is, by controlling the combustion conditions in the decomposition furnace and pipeline, the CO produced by incomplete combustion was used to reduce NOx , and the denitrification efficiency of staged combustion technology was about 30% (at present, there is a new breakthrough, which can achieve ultra-low emissions). After achieving ultra-low emissions through the application of catalytic reduction technology (SCR) in the coal-fired power industry, the introduction of this technology (SCR) into the cement industry has gradually matured through the adaptation period. However, the increase in costs and the generation of hazardous wastes are still issues that enterprises need to consider. In recent years, on the basis of staged combustion technology, through the study of combustion conditions in the calciner and pipeline, considering the use of reductants and the generation of hazardous wastes as far as possible, the deep denitrification technology of pipeline reduction method has been put forward. Through The main chemical reactions are as follows: CO2 + C → 2CO2CO + 2NO → N2 + 2CO 24 CO + 2NO2 → N2 + 4CO2 Pipeline Denitration Process Flow Diagram reduction kiln is finished in the pipe denitration furnace, the pipe denitration furnace is arranged between the kiln tail smoke chamber and the decomposition furnace, an air inlet of the denitration furnace is connected with a necking opening at the top of the kiln tail smoke chamber, and an air outlet of the denitration furnace is connected with the bottom of the decomposition furnace. The inlet end of the denitration furnace is provided with a pulverized coal inlet and a material inlet, coal is fed in the denitration furnace to generate CO, and material is fed in the denitration furnace to balance the temperature in the furnace. Benefits of applying pipeline denitration technology: 1.2.3 . Pipeline denitration application case: Southern Cement cooperated with Zhengzhou Aotong to carry out pipeline denitration technology transformation in four companies of Southern Cement, including Jiangshan, Shanya, Sanming and Changde, and achieved good results. In May 2023, the technical research team of the State Inspection and Quarantine Group investigated the technical transformation of Jiangshan, Shanya and Sanming companies, and concluded that the pipeline denitrification technology was stable in operation, easy to operate, and achieved ultra-low emission indicators. Compared with similar technologies, the investment was reasonable, the operation cost was low, and there was no catalyst consumption. The pipeline denitration furnace has the advantages of low operation cost, no secondary pollution, ultra-low emission, energy saving and carbon reduction, and is a development direction. In order to realize ammonia-free denitration, further research is needed: 1. Study how to reduce the air leakage of the air lock valve. 1 , ensure that that gas containing NOx in a smoke outlet cham does not enter or less enters the decomposition furnace and C5, and denitrify through the pipe furnace as much as possible; .
浙公网安备33010802003254号