Due to its structural characteristics, tube and tube heat exchangers are prone to dirt“haven”, when the ash content of the flue gas is large, the flow rate of the flue gas is low, or dew point corrosion occurs, a large thermal resistance of dirt will be formed.
When the fouling thermal resistance accounts for an excessively large proportion of the total heat transfer thermal resistance, the design calculation of the heat exchanger will be meaningless. Because the dirt thermal resistance is estimated and selected, while other thermal resistances are calculated through various formulas and correlations.
In addition, the thermal resistance of dirt is too large, which will causeTube and tube heat exchangerThe area increases, which increases the operating and investment costs of the equipment. If the heat transfer performance of the equipment is good in the initial operation stage, but after a period of operation, the heat transfer effect is found to be reduced, the main reason is probably due to dust and dirt accumulation.
At the design stage, it is recommended to set a numerical range that can tolerate fouling thermal resistance, for example, take20%. If the thermal resistance of dirt is greater than this value, the designer should take appropriate measures to control it.
Countermeasures:
1, Increase the flow rate of the fluid so that the fluid has good self-blowing ability.
2, Adjust the structure, such as increasing the spacing between components and tubes, or using other components that are less likely to accumulate dust.
3. Install a soot blowing device and adopt a good active descaling method.