| Title | Design of an H2S Absorption Column at the Hellisheiði Powerplant |
|---|---|
| Authors | Ari INGIMUNDARSON, Magnús Þór ARNARSON, Húni SIGHVATSSON, Teitur GUNNARSSON |
| Year | 2015 |
| Conference | World Geothermal Congress |
| Keywords | NGC abatement, H2S disposal, absorption column, |
| Abstract | Environmental regulations in Iceland impose conditions on disposal and abatement of H2S release from geothermal power plants. At the Hellisheiði power plant several methods of H2S disposal have been under investigations. After an initial screening the most suitable methods were determined to be absorption either with amine solvents or water. The water absorption method was selected due to cost and elimination of danger due to spills. Currently a system based on a water absorption column and reinjection is being built to handle NCG from one 45MW unit with plans to add similar systems for the other units as the technology is proven. This article discusses the main issues in the design and operation of the system. Mannvit handled the design of the system. Important experience was gained during the research project Carbfix where the aim was to optimize industrial methods for storing CO2 in basaltic rocks. A basic system description is the following. Cooled condensate is used for the absorption. It is cooled with ground water which is plentiful in the Hellisheiði area before being lead to the absorption column. The water from the absorption column is then lead to a booster pump where the pressure is increased before reinjection. Two system aspects reduce the risk of depressurization of the gas rich water during reinjection. The pipeline into the reinjection well is extended down into the well. Secondly a separate water pipeline supplies water to the well head to maintain pressure in the well. It is assumed that 98% of the H2S will be cleaned with this method. Lighter gases, not absorbed and part of the CO2 are vented at the top of the absorption column. The other part of the CO2 is dissolved in the water in the absorption column and injected with the H2S. |