(602j) High Pressure, Oxygen Blown Entrained-Flow Gasification of Bio-Oil

The goal of this research is to investigate the gasification of bio-oil in a pressurized entrained flow gasifier.  Gasification at high pressure is essential for integrated gasification combined cycle power (IGCC) and efficient syngas upgrading to fuels and chemicals. Feeding solid fuels into high pressure reactors is one of the most difficult challenges of gasification.  Dual chamber lock hoppers are an expensive and sometimes unreliable option. Among solid fuels, coal is sufficiently hydrophobic to be mixed with water and pumped at high pressure as high-solids slurry.  Biomass is too hydroscopic to be pumped in this fashion.  Bio-oil from fast pyrolysis of biomass is essentially “liquid biomass” that can be pumped at high pressures.  

This gasifier operates with active electric insulation at temperatures of 700^°C to 900^°C and under pressures up to 50 bar to simulate the operation of industrial-scale gasifiers. The gasifier consists of two sections:  the reactor and the quench vessel. The gasification section is constructed of a 1.0 m long, 3.8 cm dia. silicon carbide tube surrounded by several layers of insulation and encased inside a 15.2 cm dia. stainless steel pressure vessel.  Hot syngas entering the quench vessel is sprayed with water to reduce gas temperature to below 100°C followed by pressure let-down and exhaust.  Product gases are analyzed by gas chromatography. The system can gasify up to 2.5 kg/hr of bio-oil in oxygen and steam flows of 1.0 kg/hr.

Tests were performed on two bio-oils from the pyrolysis of switchgrass and cornstover using design of experiment protocols.   This allowed the construction of statistical models to predict the effect of biomass composition, gasification temperature and pressure, and biomass/oxygen equivalence ratio on gas composition.