Dear Marcin Stec'

First of all please tell me i your instrument what types of detector are installed for the analysis of all Biogas components?

Dear Muhammad

We are using Siemens Ultramat 23 analyzer using NDIR (nondispersive infrared sensor) with additional electrochemical  oxygen measuring cell.

In biomass gasification you would hardly get any measurable sulfur dioxide. Other oxides might be responsible for the false results.

Dear Jai,

Thank You for Your answer, which is in line with our observations. However even errorneous information could be valuable if one can connect it somehow with a process. Rapid increase of the SO2 reading (from 0 to 200ppm) occurs when we change the conditions from oxidation (plant start-up) to gasification (normal operation). It suggest that the compound is being created in reducing condtions.

Do You suspect what compound can cause such readings? Probably it must have similar IR spectrum like SO2. Or it can be just cross correlation with carbon monoxide?

Any clues?

Dear Marcin Stec,

SO2 is the product of oxidation process during coal burning, while in case of gasification main gas products are reduction process products. Therefore in case of Gasification you will receive H2S gas from sulfur contents of Coal or biomass.

So you must switch to a detector that can detect H2S in the product gas components.

Regards.

Dear Marcin

First of all check the sulfur content of your coal sample. Secondly, in all probability the carbon monoxide is the culprit for the false reading.

Dear Muhammad and Jai,

Thank You for the involvement. The culprit (accurate description) was found - it is carbon monoxide. I've compared trends of CO and SO2, and verified the composition of gas using chromatography and no measurable sulfur compounds were found. An the comparison of CO and SO2 trends prooved that they are correlated.