EFFECT O F MOLECULAR STRUCTURE ON COMBUSTION BEHAVIOR.
L. C. Gibbons, H. C. Barnett, and Melvin Gerstein
2150
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2160
AIRCRAFT TURBINE FUEL PROPERTIES AFFECTING COMBUSTOR CARBON.
D. P. Barnard a n d Lamont Eltinge
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CORROSION AND DEPOSIT I N GAS TURBINES. B. 0. Buckland .
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STABILITY OF AIRCRAFT TURBINE FUELS.
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C. R. Johnson, D. F. Fink, and A. C. Nixon
Although the gas turbine had limited application 25 years ago, its rapid development, based on liquid fiiels, has really occurred during the last 10 years. The turbojet engine for airplanes and the more recent turboprop engine have received the most coverage in the news, but the heavy land-based turbine, liquid fuel fired, has also been publicized recently. This symposium outlines the fuel problems of both engines and the fuel quality restrictions imposed by these problems. The turbojet engine of 10 years ago seemed to be a relatively simple device compared w-ith the aircraft reciprocating engine. Designers of conventional engines referred to it rather contemptuously as “a can, built w-ith tin snips and pliers.” It was originally built to run on kerosine, but the idea grew t h a t it w-as really omnivorous-that it would run on practically anything. Offhand, burning a fuel in the combustor of a turbojet engine seems a good deal like burning it i n a furnace firebox, but the analogy breaks down rather quickly when the volume of fuel burned and heat released in a given volume of combustor are considered. It is the enormous heat release requircment that makes the turbojet engine so particular about its fuel. The original jet fuel i n the United States was a kerosinelike fuel, known as JP-1. Unlike kerosine, however, it had to remain liquid a t temperatures as low as -76“ F. Not many crudes will produce this type kerosine, and it was almost immediately evident that the limited availabilit5 of such a fuel made it impractical for military purposes. However, a kerosine-type fuel is still the choice for commercial aircraft turbines.
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2166
O n the theory that the jet engine could be designed to burn any clean petroleum fraction, provided i t was moderately well standardized, the JP-3 fuel was developed. This fuel was of maximum availability from the crude, considering the tw-o basic requirements that it be completely liquid a t -76“ F. and that i t have a vapor pressure corresponding to that of aviation gas-about 7 pounds. The original JP-3, introduced i n 1947, therefore included practically everything i n petroleum products from pentanes to fractions boiling a t 600’ F. Since 1947, engine development has indicated other restrictions that had to be applied to jet fuel to ensure both proper combustion and proper handling in the airplane. One of these restrictions developed because the engine liked the high vapor pressure fuel but the fuel handling system of the airplane did not. Accordingly, the JP-4 specification, issued in 1931, provided for a vapor pressure of 2 to 3 pounds or a largely depentanized fuel. The heavy land-based (or marine) gas turbine has presented different problems. The heat release per cubic foot is not so important as the combustor can easily be made big enough to take care of combustion problems. The gas turbine must be economically competitive with the Diesel and the steam turbinh. This means that i t must be capable of running on a cheap fuel-viz., residual fuel. The turbine, therefore, must handle the ash and metallic Constituents of the fuel along with the combustion gases. The corrosion and deposits resulting from these constituents are the real problem of heavy turbines.
J. BENNETT HILL
Presented before the Division of Petroleum Chemistry, 125th Meeting, ACS, Kansas City, Mo.
October 1954
INDUSTRIAL AND ENGINEERING CHEMISTRY
2149
