Catalytic pyrolytic gasification of biomass for bio-lng production
Because fossil energy sources are limited for heating, cooking, power and small transportation vehicles alternative energy sources are found that are based on sustainable power generation. For large transportation vehicles and aeroplanes liquid fuels are a better sustainable solution.
Research is done for the production of liquid fuels originating from biomass sources. A promising transport fuel is pyrolysis oil. But this has some drawbacks like the low energy content and its corrosive nature.
In this thesis results of research what is done on producing bio-LNG from a methane-rich pyrolysis gas are presented.
An experimental set-up is designed and build for catalysed biomass flash pyrolysis. This set-up incorporates a fluidised bed reactor for the pyrolysis of biomass under controlled conditions with a high heat rate of the biomass. The fluidised bed material consists of only quartz sand or catalyst to increase the methane concentration in the produced gas. The second reactor is a fixed bed reactor containing different catalysts to convert the produced gases even further to methane. The produced gases are cooled and the oil is condensed in a new designed spray condensing system. The capacity of this set-up is 1 kg/hr. The whole chain of the production of LNG from pyrolysis gas is modelled with flowsheeting program Honeywell Unisim Design R410. The model consist of the acid gas removal, dehydration, feed compression and liquefaction steps.
The new experimental set-up operates appropriately. The experiments in the set up showed a maximum CH4 concentration of 26 vol% in the exhaust gas with a nickel catalyst in the fixed bed reactor. The maximum CH4 yield was 11 kg CH4 per kg biomass. The simulations with the model of the bio-gas liquefaction process show that the methane concentration in bio-gas have to be at least 60 vol% to be suitable for liquefaction to bio-LNG.