What are the structures and features of the horizontal double-drum water-tube boiler?
2022-06-22
The double horizontal drum water tube boiler is mainly composed of upper and lower horizontal drums, convection tube bundles, water wall tubes, downcomers and headers and other pressure components. The front part of the boiler is the furnace, and the water walls are arranged around the furnace; the upper and lower horizontal drums are located at the rear of the furnace, and the two drums are connected by curved water pipes. Combustion equipment mostly adopts chain grate, and some are pulverized coal furnace or boiling furnace, equipped with superheater, economizer and air preheater. The high-temperature flue gas flows from the upper part of the furnace through the heater and enters the convection flue, first downward and then upward in an S-shape, scouring the convection tube bundle horizontally, and then folded down into the tail flue after reaching the upper part. The heater is exhausted into the atmosphere by the induced draft fan and the chimney. The boiler evaporation is generally less than 20 tons/hour (t/h), and the working pressure is less than 2.5 megapascals (MPa).
The water cycle of the double horizontal drum water tube boiler is divided into two parts: one part is the water circulation carried out by the convection tube bundle between the upper and lower horizontal drums; the other part is the water circulation carried out by the water wall tubes around the furnace. The soda-water mixture directly enters the upper drum, while the soda-water mixture in the water-cooled wall tubes on both sides needs to enter the upper drum through the upper header and the steam guide pipe. The water in each water-cooled wall pipe is supplied by the descending pipe drawn from the lower drum.
The advantages of the double horizontal drum water tube boiler: reasonable and reliable structure, good load adaptability, high thermal efficiency, convenient operation and maintenance, and low labor intensity. Disadvantages: high volume, high consumption of frame metal; high requirements for water supply quality and the technical level of the stoker.
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