Since the cross section inside the pipe is smaller than that outside the tube, the steam flow rate is greatly increased, and the steam generated on the heated surface is immediately washed away, which increases the heat absorption rate of the pan water. Boilers with higher pressure and larger evaporation are water tube boilers. The so-called water tube boiler is a boiler in which water, steam or steam-water mixture flows in the tube, and flame or flue gas burns and flows outside the tube.
Advantages of using industrial water tube boilers：1. The industrial 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 industrial water tube boiler drum is generally not directly heated, and the tube containing the 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 in the industrial water tube boiler is completed in the economizer, the water wall and the convection tube bundle, and the superheater on the heating surface.
4. The industrial water tube boiler water vapor system, combustion system and auxiliary system are more complicated, but the structure of the single pressure-bearing component of the water tube boiler is relatively simple.
5. Because of the preheating of water, steam superheating of industrial water tube boilers, the pipe fouling is difficult to remove. Therefore, water tube boilers have higher requirements on water quality and higher requirements on operation, operation and management.
Disadvantages of using industrial water tube boilers：
1. The structure is complicated, the manufacturing cost is much higher than that of the fire tube type, and the cleaning is troublesome.
2. The impact caused by scale is quite large and the water quality requirements are strict.
3. Due to the small capacity of the steam drum and water drum of the water storage, it is easy to cause the phenomenon of steam and water to rise together and generate steam with high humidity.
4. The water tube is in contact with high-temperature combustion gas for a long time and is easily damaged.
5. The steam storage is small, so the pressure changes greatly.