Fabrication, Optimization and Purification of Syngas from Rice Husks; A Value Chain Addition Strategy for Rice Farmers in Mwea, Kenya

Abstract

Thermal gasification of biomass provides a potential renewable energy resource in rural areas in Kenya. Rice husk obtained from Mwea, Kenya was converted into combustible gas (syngas) using a locally assembled modified updraft gasifier. The optimal gas production was achieved at a temperature of 700 oC with injection of limited supply of air, the resultant gas was purified using series of gas cleaning and cooling devices; namely concurrent spray water tower, countercurrent spray water tower, a cyclone separator, a venturi scrubber, a solid adsorbent loaded with fine wood dust and series of coarse and fine fabric filters. The raw and upgraded gases were analyzed for compositional analysis. The upgraded gas was used for direct heating in a modified stove and to run a modified internal combustion engine coupled with an electricity generator for electricity generation. Process water recycled and treated before discharge. Spent rice husks which are fully carbonized were used to make energy briquettes and part of it applied to the rice growing pads to improve soil properties. The technology provides energy solutions to off grid communities and also aids in the abatement of climate change. The project was thus qualified as a value chain addition
project for rice growers since extra income can be generated through syngas production and sales. The upgraded gas can be utilized in direct heating applications as well as in combined heat and power (CHP) systems. The carbonized husks can be used on rice growingpads to promote soil permeability and porosity. The project can also be used as a Clean Development Mechanism (CDM) for climate change mitigation and abatement since it provides a permanent carbon sink.