Energy & Power Generation Consulting,
Engineering & Management Services



Hydrogen Sulfide Abatement System

PROJECT: Hydrogen Sulfide Incinerator Replacement for Geothermal Generation

A large number of generating units were installed in the Geysers area around Clear Lake, CA, while PG&E owned these facilities. A by-product of using the steam out of the ground is the off gassing of hydrogen sulfide (H2S) gas which has a strong odor of rotten eggs. While PG&E owned these units, the local air pollution control district implement regulations to control release of H2S gas. PG&E had their Department of Engineering Research build a pilot incinerator at one of the generating site's location. In the year 2000, this pilot incinerator was at least 5 years old and was failing. An independent power producer (IPP) purchased the majority of PG&E's geysers units and also bought a used incinerator of much larger capacity to replace the pilot incinerator. The used incinerator system consisted of a simple antiquated hardwired analog control system using basic control theory to maintain combustion and quenching water flow rates.

The IPP requested that the control system be upgraded to an Allen-Bradley ControlLogix PLC including building the burner management system in a stand-alone ControlLogix PLC. The IPP specified that process safety and stability were a premium due to past challenges from the original prototype incinerator. Therefore, process and control engineering design, testing, construction, and startup services were provided for a completely new and upgraded control system. Included in these services was the development and finalization of the functional process organization for H2S abatement.


• Completely characterized and established the initial and final tuning parameters for all the PLC controlled processes for the H2S incineration process. Unit was commissioned as the most stable incinerator owner had in service.