Advanced coal based power generation systems such as the British Coal Topping Cycle offer the potential for high efficiency electricity generation with minimum environmental impact. An important component of the Topping Cycle programme is the gas turbine, for which development of a combustion system to burn low calorific value coal derived fuel gas, at a turbine inlet temperature of 1260°C (2300 F), with minimum pollutant emissions, is a key R&D issue.

A phased combustor development programme is underway burning low calorific value fuel gas (3.6–4.1 MJ/m3) with low emissions, particularly NOx derived from fuel bound nitrogen.

The first phase of the combustor development programme has now been completed using a generic tubo-annular, prototype combustor design. Tests were carried out at combustor loading and mach numbers considerably greater than the initial design values. Combustor performance at these conditions was encouraging.

The second phase of the programme is currently in progress. This will assess, initially, an improved variant of the prototype combustor operating at conditions selected to represent a particular medium sized industrial gas turbine. This combustor will also be capable of operating using natural gas as an auxiliary fuel, to suit the start-up procedure for the Topping Cycle.

The paper presents the Phase 1 test programme results for the prototype combustor. Design of the modified combustor for Phase 2 of the development programme is discussed, together with preliminary combustion performance results.

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