Cement, Energy and Environment

to discard old pre-heater tower and go for 6-stage energy-efficient pre-heater tower. Orelse they can retain old tower and go for Waste heat recovery power plant. If waste heat recovery (WHR) power plants become cheaper, the age-old 4-stage pre– heater system may be preferred one in future. Electrical Power from Waste Heat Recovery Power plants can meet nearly 40% of the power requirement of the Cement plant. The moisture content in raw material would be limiting factor for the number of stages in the pre-heater. Modern Pre-heater cyclone is low pressure and high efficiency type. Replacement of old pre-heater top cyclone with modern low pressure cyclone itself would result in good energy saving in the kiln. Clinker cooler hi:ls also undergone significant change. Modern air beam type coolers have much higher efficiency, and retrofitting the same in old coolers is much easier now. 4-stage 5-stage 6-stage Above 6-stage 100% 112% 117% 780 760 730 100% 125% 150% Preferred where the raw material moisture is more than 5%. Ideal design in all respect if raw material moisture is around 5% or less High investment and not suitable if AM moisture is more than 3% High fan power would offset heat saving. Very high investment. Incidentally the PPC cement production also reduces the power and heat requirement to a great extent and hence significantly saves cost of production . The following table compares energy and cost of production between OPC and PPC/ PSC. Portland pozzolana cement with 30% fly ash (PPC) Portland pozzolana cement with 60% slag (PSC) Ordinary portland cement (OPC) Fossil fuel available on earth is not unlimited. At the present rate of consumption, availability of fossil fuel would come to an end in the near future. Mineral oi l would last 44 years, lignite 63 years, gas 68 years, and coa l 150 years. Substitution of mineral oil with bio-fuel like ethanol is catching up all over the world. Future generation would curse us for over-exploitation of natural resources and leaving the earth high and dry for them. In the word of our Father of the Nation, "World has enough resources for everyone's needs but not enough for everyone's greed". "Civilization means not multiplication of wants but deliberate and voluntary reduction of selfish wants ." 79.50 70.00 76.00 71.58 40.00 52.00 100.00 100.00 100.00 Mining of fossil fuels causes soil degradation and deforestation. Fossil fuels emit harmful carbon dioxide, sulphur dioxide, nitrogen oxide gases, and microbial dust particles in burning. They produce huge quantity of ash which is difficult to dispose. Co-incineration of harmful wastes like municipal solid wastes, ETP wastes, and paint wastes along with fossil fuel reduces the requirement of fossil fuels and destroys harmful substances in the waste. The Use of waste fuels conserves the scarce fossil fuels. The cement industry is the ideal incinerator of all harmful chemicals and wastes. In foreign countries there is stringent law to make