1156 posts
Quality control Question 29
I've been working with analysers for the cement plants for last nine years and have still a little doubt about the actual use of measurement of NOx in the kiln inlet. If you can kindly send me some literature about the firing in the kiln and the advantages of measuring various gases at the kiln inlet.
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1156 posts
Re: Quality control
The NOx level at the kiln inlet is a very good indication of the burning zone temperature in the kiln. In turn this is one of the most important considerations in the control and optimisation of the kiln. NOx arises from two sources, (i) organic nitrogen in the fuel, and (ii) oxidation of the atmospheric nitrogen in the combustion air drawn into the kiln. This oxidation of the atmospheric nitrogen rises in direct proportion to the temperature in the flame and the burning zone.
1156 posts
1156 posts
Re: Quality control
The Rosin-Rammler-Sperling-Bennett particle size distribution for cement is found by measuring the residue on various sieves (25,32,45,63,90 microns etc.) Alternatively you can use laser granulometry or some other method of measuring the residues. You then plot the natural log of the sieve sizes on the x axis (ln(sieve)), against the double natural log of 100 divided by the residue on the y axis (ln(ln(100/Residue))). The reason for using these axes is that for fine powders such as cement the plot approximates to a straight line. The slope of the line gives a measure of the "tightness" of the particle size distribution and varies from 0.8 to 1.1 for cements, dependent on the type of equipment used for grinding. The characteristic grain size is the sieve size where 36.8 per cent of the cement would be retained. This can be calculated from the slope and intercept of the RRSB line and is typically between 20 and 30 microns for cement.