Switching to solid fuels in cement plants – technical solutions and case studies: Suchismita Bhattacharya, Penta India Cement & Minerals Pvt. Ltd (India)
Filmed at Cemtech MEA 2015, 8-11 February, Grand Hyatt Dubai, UAE
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So solid fuels along with alternate fuels have, when you try to incorporate flexibility there are certain requirements and certain things one has to keep in mind, and that's going to be the focus of my presentation today. State of the art cement kilns today with the ILC systems, inline calciner systems, pre-heaters up to six stage consume around 700 kilo-calorie per kg of clinker. This specific heat consumption obviously depends upon technology, the older plants, wet process plants were higher, higher than 800, 900, some of the cement plants even with new technology when they're not functioning optimally, they have higher heat consumptions around 800 kilo-calories per kg.
When it comes to electricity consumption, the specific power consumption for per ton of OPC that is CEM I cement would be around 100 kilowatt hours per ton, and whereas the best performing plants have gone down to almost 80. As if you had more fly ash in your cement then obviously you'd achieve lowered consumptions as far as electricity is concerned as well as fuel.
A comparison of coal, fuel, oil and gas with respect to heating values, there is a range especially for coal because the range is wide because you have different types of coal and they have different properties which I will discuss in a bit. Why switch fuels? As most of you operating in this region are aware, there is fluctuating price of your traditional fuels, in some areas there is non availability of natural gas, I understand Egypt has had to shift to coal based firing in the last couple of years.
Also other causes could be social causes, economic causes may be even health issues or epidemics in certain areas where you don't have access to a certain fuel that you are having access to. So in today's day and age, it makes sense to have a flexibility with regarding to your fuel use in your cement manufacturing system.
So when you're trying to add in another kind of fuel or to switch to solid fuel, with respect to fuel what were the things you will need to consider? If it's coal you need to know what type of coal it is, how fine you need to grind your coal, whether it's pet coke or coal, there would be differences in volatility which in turn causes you to grind finer in one case. If it is alternative fuel as we've just seen earlier this morning, a lot of things need to be taken care of and with alternate fuels you have a separate waste, if you're doing a waste-based fuel or a waste-derived fuel, you would have a waste processing plant maybe as apart of your fuel-handling facility.
And most important, whenever you're dealing with this new entity, whether it is fine-ground coal or alternate fuel, you have safety requirement for fuel handling and transport. And this is something, what happens is you may put in the best systems but the people in your plant also need to be aware of all the hazards or all the new requirements, not necessarily you're going from a more difficult situation but it's a different situation and you need to train your workforce to deal with handling the different kind of fuel.
So these would be with respect to fuel. We'll move onto process considerations. Well let's say you have decided on a kind of fuel, you would make to make or tweak your pyro-processing slightly to get your cement clinker in the same quality. So what else would you have to deal with,