Re: High fuel consumption

Asim,

Assuming everything is normal in your fuel, you might try to check your feed to speed ratio and verify sources of air leaks in your system.

Reduce your tons/rev or reduce your filling degree. Most, but not all maintain 13% kiln loading and lower. It could help a bit. I've tried it in many kilns and is a proven fact. Just make sure that the calciner can take the small addition of fuel. there will be a transition of heat distribution at the kiln and calciner when you do this. It's a nice experiment.

Check for possible air leaks.

Re-check your coal feeder calibrations or do a loss-in-weight on the bins. This also holds with the kiln feed.

Denis

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Re: High fuel consumption

It is due to kiln feed dilution from the preheater tower.

When u use hot gas fro coal mill from downcomer, it carries the kiln feed from the tower. This will mix with coal and dilute the heat value

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Re: High fuel consumption

Dear Rajesh,

How much kiln feed will be entrapped by existing gases. The very high value of ash does not corroborate that.

I am very doubtful on the result of blended coal. There is something wrong either with sample or testing.

It is true that dust will lower caloric value of fired coal, but it will increase amount of coal proportionately. On this account, ultimately specific thermal will remain same.

Regards,

Gulam Dastgir 

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Re: High fuel consumption

If you measure the heat value of the purchased coal (on dry basis),
if you measure the consumption of the kiln from what you purchased,
if the kiln specific consumption doesn't change significantly,

then the heat cost of the kiln, or the amount of purchased coal, should not change significantly if meal is mixed with coal during drying.

As long as the flame temperature does not drop too much, the mixing of coal with meal should have no significant effect on the kiln specific heat consumption. The meal doesn't increase the specific amount of exhaust gas, but it simply decreases the flame temperature.

The mixing of coal with meal could increase the specific heat consumption only if the flame temperature drops so much that the heat exchange in the burning zone becomes borderline. Should this occur, the burning zone should become longer to compensate or the production should be decreased. However, all this cannot increase significantly the heat transfer since this has no impact of the flame temperature itself. Practically, when the flame temperature decreases too much it is simply not possible anymore to produce quality clinker. There is no practical way to compensate significantly because the effect of insuffisient heat transfer increases very fast with the temperature drop below the limit.

Generally speaking, an increase of specific heat consumption must be reflected in the heat losses. This means:

• either, that the clinker should become hotter which is unlikely since the cooler is unaffected
• or, that the heat lost with the exhaust gases must increase which can occur:
  - if the amount of gases increases, which cannot happen by adding meal
  - or if the exhaust gases become hotter

All that means that a kiln heat and mass balance should be performed.

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