The heating surface of the water tube boiler is composed of many small tubes, and the thermal expansion compensation performance is good, and can be arbitrarily arranged as needed. The increase in boiler pressure and capacity is not limited by the drum. The flow of steam and water can be naturally circulated, or it can be forced circulation or water vapor to pass through the heated surfaces in turn, not only can the heating surfaces be well cooled, but also the heat absorbed by the unit heating surface increases. The heating surface is all outside the drum, and the boiler of the water tube boiler is relatively small. The DC boiler is used, and the drum can be eliminated, so the metal usage rate of the water tube boiler is low.
After the water tube boiler adopts superheater, economizer and air preheater, the exhaust gas temperature can be reduced to 100~150°C, and the boiler efficiency can reach over 90%. In addition to high thermal efficiency, water tube boilers have the following advantages:
1.The water tube boiler furnace is placed outside the cylinder, and the volume of the furnace can be large or small, which can meet the requirements of combustion and increase of evaporation.
2.The water tube boiler drum is generally not directly heated, and the tube for containing water vapor is placed in the furnace and the flue as a heating surface, and the heat transfer performance and safety performance are significantly improved.
3.The preheating, soda and steam superheating of the water tube boiler water is completed in the economizer, the water wall and the convection tube bundle, and the superheater on the heating surface.
4.The water vapor system, combustion system and auxiliary system of the water tube boiler are relatively complicated, but the structure of the single pressure-bearing part of the water tube boiler is relatively simple.
5.Because the water boiler preheating, soda water and steam superheat are all completed in the pipe, the pipe fouling is difficult to remove. Therefore, the water pipe boiler has higher requirements on water quality and requires higher operation, operation and management level.