1156 posts
Fuels Question 7
Our government is starting to limit NOx emissions from cement kilns and the regulation, as I heard, was more severe than in the European countries. I think the best way for reducing NOx emission with no further cost is to use fuels that contain the lower nitrogen content, especially coal and residual fuels. Am I correct?
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1156 posts
Re: Fuels
The NOx emissions arise from two sources: (i) the nitrogen in the fuel as you say, and (ii) "thermal" NOx from the breakdown of atmospheric nitrogen at the high temperatures in the burning zone. Usually the thermal NOx is much higher than the fuel NOx and the best way to reduce NOx emissions is to reduce this thermal NOx. Low NOx burners reduce the temperatures in the flame and produce less NOx by using less primary air. Low NOx calciners burn some of their fuel in a depleted oxygen environment to cause NOx degradation by the following reaction: NO + CO -> 0.5N2 + CO2. These are the best way sto reduce the NOx emissions of the kiln.
1156 posts
Re: Fuels
The first thing you must do is tie down the source of the variable chloride input to your kiln. This must be in one of the raw materials or the fuel. If one of the raw materials perhaps you can solve the problem by selective quarrying. Operating the burner in a reducing manner will not affect the chloride recirculation but will greatly enhance the sulphate recirculation. If you have any incidence of CO at the kiln inlet then you are operating ina reducing manner and are likely to have sulphate based problems. The way to avoid this is to adjust the flow of fuel and primary air to the burner.
1156 posts
Fuels Question 9
I witnessed a phenomenon at a plant here in Europe, which could not be explained by anybody there. At one plant I found ring formation at the upper transition zone in a rotary kiln at three different areas. The plant is burning alternative fuels like house trash, plastics and bone meal. I was told, that all actions taken with regards to the process, have not been successful. My questions are:
1. Is there anything you could recommend apart of the standard procedures to avoid coating formation?
2. Do you know, if there is any refractory manufacturer who does supply are fractory solution for this matter and what should be the technical data for such a refractory?