A review on emission analysis in cement industries
Introduction
The cement industry is one of the major contributors for greenhouse gases (GHG) emissions, specifically CO2 emission. This is due to the calcinations of raw materials for the production of cement and burning fuels needed to maintain high temperatures in a Kiln. In recent times, one of the most important goals of the global environmental agenda is the reduction of emissions to protect the Earth's climate pattern. The increasing trend of atmospheric emissions is a driving factor to design and develop policies to overcome challenges facing by climate change.
Cement industry subsector require about 12% of total energy use in Malaysia [1] and 15% in Iran [2], [3]. It is observed that coal, fuel oils and petroleum coke are the major sources of energy needed in a cement manufacturing process. Recently natural gas, and alternative fuels found to be used by many cement industries around the world [4]. Approximately seven percent of the total CO2 is emitted by cement industries [5]. This percentage is rapidly increasing mainly because cement production is increasing at a faster rate than the speed at which emissions are presently reduced [6].
China is the major cement producer around the world and it produced 1388 million metric tons (MMT) of cement in 2008. This accounts for nearly half of the world's total cement production [7]. Indian cement industry is the second largest in the world with an installed capacity of 135 MMT per annum. It accounts for nearly 6% of the world production [8]. At present, the United States is the third major cement producer in the world next to China and India [4]. In 2002, the United States produced 89,000,000 metric tons of cement [9]. Fig. 1 shows worldwide cement production statistics [10].
Section snippets
Specific energy consumption
A plant or process with a lower SEC value corresponds to a similar plant or similar process that is more energy efficient. By comparing to SEC, the information developed can be used to assess the energy-efficiency potential of a plant. The SEC can also be used for evaluating and tracking a plant's progress in energy-efficiency improvements by eliminating the effects of a change in product mix [11]. Average specific thermal and electrical energy consumption is presented in Table 1 for few
Emissions from cement industry
About one third of the global carbon dioxide (CO2) emissions released to the atmosphere are associated with the use of energy at various industrial sectors [14], [15] reported that industry emitted about 2370 Tg CO2. This accounts for about 43% of global CO2 emissions. Deja et al. [5] reported that cement industries contribute for about 7% of the total global CO2 emissions. It is estimated that about 0.9–1.0 tons of CO2 are produced for a ton of clinker depending on the type of fuels used [5],
Reduction of emissions from cement industry
The cement industry is one of the largest sectors that contribute emissions of CO2 to atmosphere. This sector accounts for about 1.8 Gt of CO2 emission annually [25]. At the moment, CO2 reduction is the most important environmental target worldwide in order to reduce the atmospheric concentration of greenhouse gases. Followings are the few selected techniques that can be used to reduce CO2 emissions from the cement manufacturing process [20], [22], [23], [26], [27], [28]:
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Use of waste heat as an
Conclusions
It has been found that cement manufacturing is an energy intensive industry consuming about 12–5% of total industrial energy use. Therefore, sizeable amounts of emissions are released to the atmosphere as a result of burning fossil fuels to supply energy requirements of these industries. Emissions are produced from the calcinations process as well. For these reasons, special attention is needed on the clinker production to reduce CO2 emissions. It was identified that there are several effective
Acknowledgements
The authors would like to acknowledge the financial support from the Vice Chancellor, University of Malaya. This research was carried under the High Impact Research Grant (HIRG) scheme.
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