57 posts
Re: Mass Balance
subtracting Ash in clinker form g we get Amount of feed required to produce on kilogram of clinker
For me, not exactly. Subtracting Ash in clinker from g, you get the amount of meal required to produce a kilogram of clinker and this is not equal to the amount of feed. To get the feed, you need to add the amount of dust that is leaving the top stage of preheater with the gases. Depending on the efficiency of the cyclones, the feed will be several percent higher than the amount of meal calculated.
To be completely precise, you also have to take into account any other dust loss, like chlorine by-pass for example, with corrections for the difference in loss of ignition.
Best regards,
O. Van Cantfort
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41 posts
Re: Mass Balance
Bingo ! O. Van Cantfor, That's the problem with this equation it doesn't account for practicality , Any how we don't use this equation unless situation utterly demands...
Er.Raza Hussaini
537 posts
Re: Mass Balance
ovancantfort:
To get the feed, you need to add the amount of dust that is leaving the top stage of preheater with the gases.
I disagree. Remember that this dust is in a separate cycle, external to the kiln. The dust that leaves the top stage of the preheater returns via the raw mill bag filter and conditioning tower dust streams which are normally recombined with the freshly-milled raw meal.
This combined stream is what is fed to the preheater, where the recycling dust fraction is again removed... and so on.
So, unless dust is being removed completely from the kiln system, the external dust cycle can be essentially ignored. i.e. for practical purposes, the kiln/preheater can be considered to be a 'black box' with raw feed + coal ash as inputs and clinker as the output.
The only dust stream that could be problematic in this scenario is the small amount that goes to the coal mill, since it would not be considered in Peray's equations. However this dust has the same composition as the dust leaving the top cyclone of the preheater and can be compensated for if this composition is known.
Best Regards,
Ted.
57 posts
Re: Mass Balance
This combined stream is what is fed to the preheater,
This is exactly what I meant. As it is generally the combined stream of return dust and fresh meal that is generally fed to the kiln, the reading you get on your kiln feed weightfeeder will be higher than what the Peray equation gives.
This is why I prefer to make a clear distinction between fresh meal (i.e raw mill production) and feed.
See it the other way around: if you take the reading of your kiln feed weightfeeder and then use Peray equation to calculate your clinker production, you are making a mistake and overestimate your production.
Unless, of course, if the preheater dust captured by the kiln filter is reintroduced directly to the preheater after the weightfeeder (and is therefore not interfering with the reading)
Best regards,