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Show Preliminary Results of C W M Combustion Tests The CWM used at PETC is made in existing mix tanks by combining preweighed water and pulverized coal. The original agitators with turbine blades are used in the 700-hp Test Facility, while the original turbine blade in the 100-hp Test Facility replaced with propeller blades. Unlike the special CWM preparation methods employed elsewhere, PETC utilizes a simple mixing method; the CWM contains approximately 60 percent Pittsburgh seam coal, pulverized by the Williams coal pulverizer to a size consist of 90 percent minus 200 mesh, and 0.5 percent Lomar D (a viscosity-reducing agent), and the remainder is water. The viscosities of CWM prepared at PETC range from 150 to 250 cp at room temperature, depending on the shear rate. The CWM shakedown tests were conducted with a standard commercial oil burner in the 100-hp boiler without additional refractory lining in the furnace tube and without any supplemental fuel. The boiler was operated at its full capacity (3450 pounds of steam per hour), at a preheated combustion air temperature above 235 F, and at flue gas oxygen levels ranging from 1.1 to 3.5 percent. Subsequently, a series of CWM parametric combustion tests was conducted at full load with two flue gas oxygen levels (2.0 and 3.0 percent) and two preheated combustion air temperatures (500 and 300°F), and at half load with a flue gas oxygen of 2 percent and preheated combustion air temperatures of 500° and 400°F. After a number of shakedown tests were conducted with supplemental fuel (natural gas), stable CWM combustion without gas assist was achieved in the 700-hp watertube boiler in September 1981. A modified Coen burner nozzle employed previously for COM combustion was used. The boiler was operated at 2/3 load (16,000 pounds of steam per hour), at 0.4 percent flue gas oxygen, and with 585°F combustion air. A bright, stable CWM flame was achieved that was very similar in appearance to an oil flame. A combustion test with CWM containing 60 percent coal was then performed to determine performance and pollutant emissions when the boiler was 14-15 |