Water tube boiler refers to an industrial boiler in which a combustion chamber and a heating surface are provided outside the drum, causing water and steam to flow in the tube. The structure is more complicated. The soda water system mainly includes drums (drums), headers, water-cooled walls, convection pipes, economizers, and superheaters. The combustion system mainly includes burners, furnaces and flues, and air preheaters. . Structures include water tube boilers, straight water tube boilers, and curved water tube boilers.
Overview of water tube boilers
Because the cross section inside the tube is smaller than the outside of the tube, the flow rate of the soda water is greatly increased, and the steam generated on the heated surface is immediately washed away, which improves the heat absorption rate of the boiler water. Compared with the shell boiler, the diameter of the water tube boiler tube is small, the working pressure is high, and the water capacity of the boiler is small. In the event of an accident, the disaster is lighter, the boiler water circulation is good, the evaporation efficiency is high, the performance to adapt to load changes is good, and the thermal efficiency is high. . Therefore, boilers with higher pressure and larger evaporation capacity are all water tube boilers. The so-called water tube boiler is a boiler in which water, steam, or steam-water mixture flows inside the tube, and flame or flue gas burns and flows outside the tube.
Advantages and disadvantages of water tube boiler
The heating surface tubes of early water tube boilers were mostly straight tubes in order to facilitate the removal of scale. With the advancement of water treatment technology outside and inside the furnace, the boiler can be guaranteed to run for a long time and there is little fouling in the tube, so a bent-tube boiler has appeared. The heating surface tube of the bent-tube boiler can be made into a more complicated shape as required, so the various performances of the boiler are greatly improved. The heating surface of the water tube boiler is composed of many small tubes, and the thermal expansion compensation performance is good, which can be arbitrarily arranged according to needs. The increase in boiler pressure and capacity is not limited by the drum. The flow of soda and water can be naturally circulated, forced circulation, or water vapor can pass through each heating surface in turn. Not only can each heating surface be well cooled, but it also increases the heat absorption per unit heating surface. The heating surface is all outside the drum, and the drum of a water tube boiler is relatively small. With a DC boiler, the drum can be eliminated, so the metal tube utilization rate is lower. The water tube boiler adopts superheater, economizer and air preheater, the exhaust temperature can be reduced to 100 ~ 150 ℃, and the boiler efficiency can reach more than 90%. The disadvantage of the water tube boiler is that the structure is relatively complicated and the volume is large, which is not suitable for mobile equipment. The relative water capacity of the boiler is small and requires high levels of automation control and operation. According to the above characteristics of water tube boilers, water tube boilers are suitable for large and medium-sized factories and power plants.