Project Information

 

Background:

The ReFood facility processes 120,000 TPA of waste food using an anaerobic digestion plant, to generate 5 MW of renewable energy which is injected into the National gas grid.

Application:

Pre-treatment of biogas to remove high H₂S and VOCs prior to the gas entering the gas to grid upgrading system. The challenges at Widnes are unique and required a large amount of study and up front design to produce a bespoke system capable of dealing with the variable gas constituents and loads that may fluctuate on a day to day basis. Additionally the system had to operate on a very low oxygen level of 0.4% to ensure that there was no more than 1% Oxygen in the biomethane when injected into the grid.

Solution:

To design, manufacture, supply, install and commission a Biogas Desulphurisation System to remove high levels of H₂S and VOC compounds. Due to the lack of available oxygen, which biological systems rely on to work effectively, the odour control system selected to remove the bulk of the H₂S is unique and specifically designed to operate at low oxygen concentrations with minimal water consumption.

Performance:

The biological system reduced the incoming 1200 ppm H₂S levels down to <200ppm, an activated carbon scrubber then lowers to <50 ppm H₂S, however because of the presence of VOC’s in the system a further polishing stage of activated carbon was installed to prevent any VOC related odours from impacting the odour of the biomethane.

Data:

Flow Rate:                     2000 Nm³/hr

H₂S Loading:                1,200 ppm

Other Contaminants:   VOC’s

Oxygen Content:           0.2%