SO3

In order to break a potassium or sulphate cycle, the ultimate countermeasures is to bypass over 15-25 per cent of the kiln exhaust gases for the bleed of volatilised material to equal the amount entering the kiln in the feed and the fuel.With bypass system we may tolerate higher than the normal Sulfur in fuel in the pyroprocessing system.

Installing the SO3 bypass is the last thing that you will do. But yes, this is good to limit the SO3 recirculation but not 'totally eliminate'. This will allow you to operate the kiln at A/S ratio of about 0.40 with manageable build up on the tower. Also, this will help the Cl recirculation as well. If you are PH fan limited, than this system helps to draft the kiln.

But keep in mind that this is very expensive to install and to operate. These are some of the facts that you need to address:

1. Your heat consumption will go up by about 200 MJ/ton (at 15-20% bypass) depending on how much you bypass

2. Increase on the power consumption

3. Increase on KF factor.

4. Where to dump or use the bypass dust which is significant for environment point of view.

5. The bypassed gases that may contain some sulphur might be an issue for the kiln stack emission.

6. Some NOx in the kiln that goes with bypass gases will be a problem for the NOx emission as well.

 

 

 

The other way of reducing the sulfur is by increasing the alkali content . If sulfur alkali ratio is maintained at around 1.1 then alkali sulfate will be formed which is a stable compound which comes out with clinker so that sulfur circulation will be reduced.

Regards

Vinayak