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FLAME SAFEGUARn CONTRULS phần 2

CompanV. Năm 1969, • Nồi hơi điện cực Hãy ý thức · Enert: Tiếp thị t bao gồm slory, Điện Thế giới, 8ep1801ber "1971. trang 70-72. Faust, Frank H. và Kaufman, lheOOore G. (ed.), Sổ tay của lnslilule dầu đốt dầu nhiệt, America, Inc, 1951. Griswold, John, Nhiên liệu đốt và FurnactJ $. Arst | igịBurnersAndBoilers IỆ FIG.51 -VIBRATING GRATE. FIG. 52 RECIPROCATING GRATE. FIG. 53 OSCILLATING GRATE. amplitude of motion that causes the grate sections to oscillate. The entire assembly is inclined toward the discharge end of the boiler to ensure movement of the coal and dumping of the ash. The TRAVELING GRATE Fig. 54 is the most popular for spreader stokers feeding larger bailers over 75 000 pounds of steam per hour . The grate is made of overlapping clips or bars in the form of a wide endless conveyor belt. It moves at speeds between 4 and 20 feet 1.2 and 6.1 metres per hour depending on steam demand toward the front end of the baiter discharging ash continuously into a hopper. It Is designed to handle a wide range of coals as well as process wastes and municipal refuse. CUTAWAY VIEW FIG. 54 TRAVELING GRATE. CROSSFEED STOKERS FIGS. 55 AND 56 Crossfeed stokers often called mass-burning stokers are well suited for a wide variety of solid fuels including peat lignite subbituminous free-burning bituminous anthracite or coke breeze. Their big advantage Is that they offer smokeless combustion at most loads. Coal is fed onto the grate from a hopper undar control of a sate. The gate establishes the thickness of the foel bed. Furnace heat ignites the coal and distillation begins. As the fuel bed moves slowly the coke formed is burned and the bed gets progressively thinner. By the time the far end is reached nothing remains but ash which falls off the grate into a hopper. Because of the variation in fuel-bed thickness airflow must vary along the bed. The grate Surface Is divided into a series of zones each with individual dampers for close control of airflow. The furnace Itself is usually designed with long rear refractory arches to direct the lean furnace gas forward and to reflect heat to ignite the foel quickly. High-velocity overfire air jets located in front of the furnace above the grate produce the turbulence and mixing required for good combustion GRATE TYPES .