بررسی تأثیر موقعیت مشعل‌های کلساینر بر کاهش نشر آلاینده‌های زیست‌محیطی کارخانه‌ی سیمان (مطالعه موردی: شهر قائن)

Abstract
Despite its great impact on economic progress, the cement industry produces a variety of environmental pollutants, including NOx, carbon dioxide, and carbon monoxide, the release of which can cause serious damage to the environment. In the meantime, the biggest impact of this industry on the environment is related to its burners, and the present research was written with the aim of investigating the effect of the location of calciner burners on reducing the emission of environmental pollutants in Qaen Cement Factory. The research method in the current research is quantitative, and in order to numerically investigate the effect of two positions for calciner burners in the lower part (main position) and in the upper part on the emission of pollutants, was used Ansys Fluent 2022 software. The findings of the research show that the Qaen cement factory in the calciner section is facing the problem of incomplete combustion, which has led to the production of carbon monoxide instead of carbon dioxide. In addition to reducing temperature and increasing fuel consumption, this incomplete combustion causes the production of significant carbon monoxide, which destroys the environment. Also, the results indicate that in the upper burner mode, due to the reduction in the chance of fuel and air mixing, the combustion becomes incomplete and the emission of carbon monoxide increases, but the production of Nox decreases due to the decrease in the combustion temperature.
Introduction
Nowadays, air pollution is considered as one of the important problems of urbanization and industrial life, and the life of all people in the society is affected by this issue. Meanwhile, one of the most important air polluting factors is cement factories. The cement industry is one of the key industries in developing countries, which is widely used in the implementation of various projects. As one of the most important construction products, cement plays an essential role in advancing the construction plans of countries, and it is used in the basic parts of construction, both as concrete and as concrete products and masonry works. However, this industry is considered one of the polluting industries. Considering the stages of cement production, which include preheating, clinker making, clinker cooling, grinding and storage operations, cement factories create dust, produce polluting and greenhouse gases such as NOx, CO2, SO2, CO, etc. in this complex process, as It is one of the known sources of environmental pollution. Meanwhile, more than 40% of the volume of carbon dioxide and carbon monoxide in the cement production process is caused by the calcination process. This importance requires that research be done in order to reduce environmental pollutants in this process. For this purpose, the purpose of this research is to investigate the effect of the location of calciner burners on reducing the emission of environmental pollutants in the cement factory in Qaen city.
Methodology
The research method in the present study is quantitative in terms of type and practical in terms of purpose. In this research, the influence of two positions for calciner burners in the lower part (main position) and in the upper part on the emission of pollutants from Qaen city cement factory is investigated numerically using Fluent 2022 software. In this research, SIPMLE algorithm is used to solve the momentum equations. Combustion flow is turbulent and the standard k-e model was used to model the turbulent flow. The combustion reaction rate, which appears as a source term in the energy equation and mass fraction survival of species, has been calculated by Magnussen's eddy dissipation model.
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Results
The findings of the research show that the Qaen cement factory in the calciner section is facing the problem of incomplete combustion, which has led to the production of carbon monoxide instead of carbon dioxide. In addition to reducing temperature and increasing fuel consumption, this incomplete combustion causes the production of significant carbon monoxide, which destroys the environment. Also, the results indicate that in the upper burner mode, due to the reduction in the chance of fuel and air mixing, the combustion becomes incomplete and the emission of carbon monoxide increases, but the production of Nox decreases due to the decrease in the combustion temperature.
Conclusion
Paying attention to controlling the effects of air, water and soil pollution in different stages of cement production, including ore extraction, loading, raw material crushing process, raw material baking process, extraction and thermal efficiency of the cement factory, will not only preserve the environment, but also improve and optimize The performance of cement factories will help a lot. Since today in our country (Iran) the establishment of cement factories, which is carried out with the use of large investments, is usually associated with job creation and other economic aspects, the development of the cement industry is going through a growing trend. But in line with these economic benefits, environmental damage caused by cement factories is inevitable. In fact, this industry is responsible for 5% of the total environmental pollution in the world, so that ignoring its environmental effects in recent decades and paying only attention to the income from this industry has caused irreparable economic and social damage to humans and the environment. Therefore, identifying the influencing elements of this industry on air pollution and environment and improving them is an inevitable necessity. For this purpose, in the present research, a numerical simulation of the calciner of Qaen cement factory was carried out. In this study, the influence of the position of the calciner burners on the temperature distribution and emission of pollutants for two lower and upper cases was investigated, and the results of this investigation are summarized as follows:
The mixing rate of fuel and air and their consumption in the calciner with the lower burner was done at a higher rate due to more opportunity. The temperature distribution in the calciner with the lower burner is more uniform and due to more complete combustion, the output temperature is higher. The mass fraction of carbon dioxide and Nox is higher for lower burner calciner due to more complete combustion and higher combustion temperature. The amount of carbon monoxide emission in the calciner with the upper burner is higher due to the lack of proper opportunity to mix fuel and air and incomplete combustion.
Keywords
Cement Industry; Pollutions; Environment; Qaen city.