Combustor development for dual fuel combustion with gas oil and biomass gasification products

A cyclone combustor was designed to enable the use of dual fuels in small gas turbines. Multiple tangential inlets enable gasified products of biomass and gas oil to be introduced separately into the combustion chamber. An integrated vortex collector pocket (VCP) was positioned just before a tangential off take. As the flow moves past the VCP the fine particles are removed from the flow. The tangential off take will draw the flow past the VCP and produce near uniform exit conditions. Results showed the combustor produced a stable swirling flame, with good mixing patterns for all cases, with LCV wood gas, gas oil and when running with a combination of both fuels. Areas of high temperature in the combustor were identified, where refractory material would be needed. The VCP performance was good, collecting particles below 10- 5m. The tangential off-take from the combustor potentially decreases the pressure drop across the system by efficiently funnelling the swirling flow into a square duct with low losses whilst pro ducing a near uniform velocity profile. Although not used in these first trials the addition of an outlet diffuser then offers potential of reducing the pressure drop by some 30 to 40%. Maximum pressure drops across the combustor of 0.1 bar were found which was an acceptable value for the process. Uniform velocity and temperature profiles were present at the combustor exit for all cases with exit temperatures between 1300 and 1350 K. The modelling shows the combustor design is appropriate for use with dual fuels and can change between fuels when running while still maintaining similar combustion patterns and stable exit conditions. The use of a VCP in the combustor removes the finer particles without the need for a further cyclone separator, which would increase the pressure drop of the system. The exhaust gas can be fired directly into an appropriate gas turbine.