Sulphur exists in process and industrial gases in the form of hydrogen sulphide. Process industries produce chemicals by chemical reactions using catalyst. Most catalyst poisoned by sulphur and thus affects the conversion rate. Hydrogen sulphide should be removed before the process gas enters in to the manufacturing units. Some of the standard reaction and reagent remove hydrogen sulphide and the reagents regenerated again for the removing sulphur compound continuously.
Sulphur removal methods for gases with chemical reactions:
- The Girbotol process use NH2 compound to react with hydrogen sulphide and can be regenerated by steam stripping.
- 2RNH2 + H2S ↔ (RNH3)2S
- Phosphate (Shell) process uses K3PO4, steam stripping is done for
- regeneration,K3PO4 + H2S ↔ KHS + K2HPO4
- Iron oxide reagent application to the sulphur containing gas reacts as,
- Fe2O3.xH2O + 3H2S → Fe2S3 + (x+3) H2O
- By oxidation with air iron oxide regenerated.
- 2Fe2S3 + 3O2 +xH2O → 2Fe2O3.xH2O +6S
- Alkazid method use the reaction,
- RCHNH2COONa +H2S ↔ RCHNH2COOH + NaHS , steam stripping performs the regeneration process.
- Seaboard developed by the application sodium carbonate,
- Na2CO3 + H2S ↔ NaHCO3 + NaHS , Air blowing is the effective method for regeneration.
- Lime the Ca(OH)2 process work by the reactions,
- Ca(OH)2 + H2S → CaS + 2H2O
- Caustic Soda the NaOH reagent treatment system.
- 2NaOH +H2S → Na2S + 2H2O
Large quantities of industrial gases contain sulphur compound that cause harm to environment. On this concern, sulphur must be recovered and safely disposed or consumed as fertilizer after treating with other elements (fertilizer components).
Industrial gases treatment by thermal oxidizer:
As the safety equipment in the chemical industry thermal oxidizer is best options to prevent leak of harmful gases into atmosphere. As the Bhopal tragedy the harmful gases when leaked from the rupture disc the organic chemicals can burned out in thermal oxidizer.