Process Innovation Via Supercritical Water Gasification to Improve the Conventional Plants Performance in Treating Highly Humid Biomass

Abstract

The aim of the paper is a comparison among three innovative process layouts for biomethane and power production from humid biomasses: anaerobic digestion (AD), supercritical water gasification integrated in a supercritical steam turbine stages (SCWG + SuST) and a technology that combines these two, AD plus SCWG and SuST. All the solutions were implemented in an ad hoc simulative tool of Aspen Hysis® v.7.0.1. Livestock sludge (LS) with an energy content up to 10 wt% (ashes free) was used as reference biomass to establish and compare the performance of any proposed process scheme. LS feedstocks introduced in the SCWG + SuST increased both biomethane production and power production of about 50 % compared to AD process that produces 25 Nm3/(day t) of pure biomethane. Combining both technologies, the digestate from AD outflow is feeding the SCWG + SuST process, there is an increase of 50 % of power generation with a production of biomethane of about 36 Nm3/(day t). Another advantage of the SCWG + SuST is that, set the fed, it is possible to reduce drastically the volume of the plant because the fermentation step, which usually corresponds to 15–30 days, is not required. Considering that although AD process is a simple and consolidated technology, it does not allow the total recovery of the organic compounds and requires long period for the biomass, the proposed innovative processes could offer new solutions for biomethane and power production.