Full-scale experience with biological biogas desulfurization using the Thiopaq technology
Driessen, W., van Zessen, E. and Visser, Paques bv, The Netherlands
(free)
Abstract:
There is an increasing interest in the production and utilization of biogas as a source of sustainable energy. However, biogas generated by anaerobic digestion from wastewater, organic resources or landfills, is often polluted with hydrogen sulphide (H2S). Hydrogen sulphide is a toxic and malodorous gas with corrosive properties in moist environments. Depending on the source for anaerobic digestion H2S levels in the biogas generally can range from 100 up to 40,000 ppmv. Besides for health, safety and environmental reasons, there is an increasing need to remove H2S from biogas, for utilizing biogas in combined heat power (CHP) units. Moreover upgrading biogas to bio-methane (vehicle fuel, gas grid injection) is becoming more popular.
In this paper long term full-scale operational data of biological biogas purification by the THIOPAQ® process are presented. The practical examples include biogas purification for utilization of biogas in CHP units as well as for the possible production of biomethane.
Key words:
Biogas, scrubbing, desulphurization, hydrogen sulphide, Thiopaq®, CHP, biomethane
Introduction:
The last 10 years there has been an increasing interest in producing renewable energy through anaerobic digestion. Apart from increased environmental awareness, local legislation and governmental incentives (e.g. UK based RHI, FIT, ROC’s) have been important drivers for the increased investments in biogas production from anaerobic digestion.
The biogas generated from anaerobic digestion of organic resources (biosolids), wastewater, or biogas from landfills is often contaminated with hydrogen sulphide (H2S). Hydrogen sulphide is a flammable, bad smelling (‘rotten egg’ odour) and toxic gas. When in moist environment it also has corrosive properties potentially affecting steel and concrete. Beside for reasons of health, safety and environment, biogas desulphurization is important, as hydrogen sulphide makes the biogas also less suitable for utilization in combine-heat-power plants (CHP), in boilers or for upgrading to biomethane.
Biogas desulphurization with the Thiopaq® technology is based on caustic scrubbing of H2S and separate regeneration of the caustic by autotrophic sulphide oxidizing micro-organism (e.g. Thiobaccilus, Thioalkalivibrio), thereby significantly lowering the specific caustic consumption.
Originally developed at the Wageningen University in The Netherlands the Thiopaq® process was first applied at full-scale at Industriewater Eerbeek in The Netherlands in 1993. Since then over 120 full-scale Thiopaq installations have been started-up treating a large variety of different kinds of biogas.
Although initially developed for desulphurization of biogas the Thiopaq® technology has also successfully been applied for desulphurization of natural gas and refinery gas. More recently research has started to test the Thiopaq technology on synthesis gasses. Though, this application is beyond the scope of this paper.
