482 CURRENT TOPICS. [J. F. I.

The Combustion Turbine. (Power, Vol. 79, no. 2. W. E. TRUMPLBR.) The combustion turbine, once deemed economically impracticable, demands new consideration in the light of today's higher turbine and compressor efficiencies and the ability of modern turbine blades to withstand high temperatures. An arrangement is described which promises a satisfactory solution of the combustion turbine. It has to do with a constant pressure cycle with regener- ation of the exhaust heat. The compressor is coupled directly to the turbine. Preheater and burner are interposed between compressor and turbine. The driven machine is also coupled to the turbine. Air is compressed in the compressor, heating it slightly, and enters the preheater which heats it nearly to turbine exhaust temperature. From the preheater it enters the burner where fuel is injected and burned with a continuous flame. The fully heated combustion gas enters the turbine, expands through nozzles and wheel, imparting power to the shaft. The partly cooled gas at practically atmospheric pressure leaves the turbine and enters a second passage of the preheater, running counterflow to the first passage. After giving up most of its heat to the compressed air, exhaust leaves the preheater at a slightly higher temperature than that of air at the end of compression. Calculations show that the proposed turbine can compare with steam and oil engine plants. As a possible application it is suggested as particularly adaptable to variable speed drive for centrifugal pump or booster in gas distribution systems.

R. H. O.