The Bureau of Mines is developing a turbine driven by hot gases from burning coal. Primary emphasis so far has been to develop and test new blades designed to resist coal-ash erosion, the major problem confronting earlier developers of a coal-burning turbine. Improved coal preparation and feeding equipment and more efficient combustion and ash separation systems also are being developed. Overall objective of the Bureau is to build and operate a machine to demonstrate the technical feasibility of an open-cycle coal-burning gas turbine power plant. In the early phases of the Bureau turbine program, tests were conducted with a machine initially built by the Locomotive Development Committee of Bituminous Coal Research, Inc. Blade erosion had been revealed as the major problem in the LDC work, so prior to initial operations a gas turbine manufacturer was asked to review the results of the previous tests and recommend a new blade design. Several important changes were recommended, and a set of blades incorporating the new features was designed, fabricated, and installed in the turbine in 1963. The initial test of the turbine was conducted late in 1963. In 878 cumulative hr of operation the blades suffered little from erosion. The rotor blades appear capable of an additional operating period of up to 10,000 hr, and the stator blades (slightly notched at the bases on the last three rows) for at least 5000 hr. The test results indicated that with further research and development blades capable of the 50,000 to 100,000 hr regarded as minimum for commercial power plants are a definite possibility. The major difficulty in the 878-hr test was ash deposition on the blades, especially the first-stage stator blades. Means of preventing or controlling ash deposition are being sought during a second 1000-hr test of the new blades in the summer and fall of 1964. Certain modifications were made in the coal-combustion, ash-separation, and coal-feeding systems prior to this test to improve operability of the turbine plant.

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