The most significant alternative fuel energy contributors to the India cement industry are agro-wastes and bio-mass fuels. A solution for alternative fuel should ensure the maximum availability of the kiln alongwith the alternative fuel feeding system and shall have minimum detrimental effect to the clinket production, say Avinash Karrahe and Venkatesh Sheshadri of FL SmidthThere is a tremendous interest in alternative fuels on a global level which holds many advantages for the cement industry.Different types of alternative fuels find their applications in different forms, ranging from hazardous to non-hazardous and they may be in the gaseous, liquid or solid state. Currently, solid fuels account for the largest part of the forms. The most significant alternative fuel energy contributors to the Indian cement industry, in particular are agro-waste and biomass fuels.The firing of alternative fuels can take place in the Rotary Kiln Burner, Calciner system or in extensional equipment, specially designed for large solid fuel particles. It is imperative that the fuels are burnt sufficiently in order to preserve the quality of the cement as well as stabilize kiln system operations. It has been observed that gaseous and liquid alternative fuels are more easily combustible than solid fuels.Distinct alternative fuels have different physical and chemical properties. Hence the mode of receiving, storage, transport and feeding system varies for each kind of fuel. A solution for alternative fuel should ensure the maximum availability of the kiln alongwith the alternative fuel feeding system and shall have minimum detrimental effect to the clinker production. Utilization of alternative fuels may result in cement plants losing production capacity for different reasons. In addition to having an appropriate design of the pyro process, it is particularly important to ensure that the alternative fuel is dosed and admitted to the kiln system in a very consistent and well controlled flow. This is strongly affected by the selected main equipments, the detailed engineering of the whole solution as well as the integration with the pyro process.Integration of Alternative Fuels in the Cement Industry :Even though utilisation of alternative fuels in the cement industry has major advantages, the introduction of alternative fuels , especially at higher substitution rates, has led to the following issues:1) What are the combustion kinetics of the various alternative fuels and how should existing/new combustion equipment be altered/ developed to obtain the desired fuel conversion?2) Will the reactivity/and or heating value of the alternative fuels cause problems with the desired flame formation in the rotary kiln?3) Will the use of alternative fuels affect emissions?4) How is the quality of the cement clinker affected by using alternative fuels?5) How does the use of alternative fuels influence kiln process stability?6) Will the water content reduce cement clinker production capacity?7) How are the alternative fuels, transported, stored, handled and delivered?The devolatilization stage in the combustion process of the alternative fuels is responsible for a large part of the fuel heating value. Kiln process stability, in particular, is influenced by insufficient carbon burnout in the calciner system, which results in reducing conditions in the material inlet of the rotary kiln and consequently an increased tendency to form deposits. Clinker quality is mainly affected by minor components from the fuel ashes or from carbon dropping into the material charge of the rotary kiln. The emissions seem not to have been affected by the alternative fuels used until now. However, caution should be taken with regard to emission of carbon monoxide while using alternative fuels.While embarking upon a change from conventional fuels to alternate fuels, it is highly recommended of cement makers to seek assistance from professional solution providers in the assessment of different options. In this regard, it can be mentioned that FLSmidth has developed a broad range of products and solutions to handle both solid and liquid alternative fuels available in the Indian industry.Alternative fuel technology is becoming a more integral part of the cement production process. No standard solutions for alternative fuel requirements are available and it is often challenging to replace traditional fuel with waste fuel, as it may influence the process in the kiln and the clinker quality, when considering a shift from fossil fuels to alternative fuels.(Courtesy: Avinash Karrahe and Venkatesh Sheshadri FLSmidth Private Limited India)