We usually do weekly the spot test in the sour water from some vessell of the FCCU gas recovery section in order to detect cyanide. Is it common to do spot test in order to detect cyanide ? Is it reliable ? What is the level cyanide to detect +/- 10 ppm ? We test the sour water from fractionator vessell, interestage vessell and high pressure vessel.
If it is the same spot test we used to run, it will show you if cyanide is present by the bluish color. I would have my chemical supplier run a sour water analysis weekly and make wash water changes according to their recommendations.
Yes. We add some FeCl3 in the paper with sour water and observe if change the colour to blue. How long does it take to change the colour ? In our case is +/- 12 h. We try to keep the wash water +/- 8 % related with the feed. The water is from the SWS (retified sou water). We add 60 % wash water in the interestage gás compressor. We observe that the wash water limit is 6 %. If the spot test show a “positive” we increase the water from 6 to 8 %. How is it the water wash limit ? What Kind of water do you use ?