s02=>s03 conversion on SCR - 0.01%S kerosene fired gas turbine

[davefitz]

I am trying to determine the typical conversion efficiency from SO2 to SO3 on the surface of a SCR catalyst.

We will install a gas fired combined cycle plant. The gas turbine will fire kerosene with 0.01% Sulphur by wt. The heat recovery steam generator will have a SCR located in a gas temperature zone at 650 F. We have a concern that the SO3 will react with the 5 ppm NH3 slip and form ammonium bisulphate.

Can anyone advise the estimated conversion efficiency to form SO3 from SO2 on such a catalyst?

 

[25362]

I can only tell what I've read on the internet on SCR catalysts, namely keep the temperature of flue gases between 610 and 780^oF for highest NOx reduction efficiency, while minimizing ammonium bisulphate or sulfate formation. Same source says that these salts are formed below 400^oF.
5 ppm ammonia slip seems to be an acceptable level, and as long as it is maintained, they say NH3 injection can be increased for better reduction of NOx.

Consulting with the catalyst supplier appears to be a reasonable approach.

 

[davefitz]

thanks 25362.

What I have determined in the meantime is:

a) typical SCR catalyst for natural gas tend to have a conversion efficiency of 3-5% at 650F for SO2==>SO3. This is due to the high levels of vanadium in the low cost catalyst.

b) at a higher price, one can specify low SO2 ==>SO3 reactivity and the resulting catalyst has low vanadium and the conversion efficiency is 0.5-1%.

c)IN the case of using 0.01%S Kerosene and a 1% conversion efficiency, the ammonium bisulphate production is not determined by ammonia slip but instead determined by SO3 generation.