Heat pipe economizer

Benefits of heat pipe economizer

 

Different with traditional boiler economizer, heat pipe economizer could transfer thermal energy by the evaporation and condensation of working fluid. It is used as flue gas heat recovery system for small industrial boiler.

 

Average thermal efficiency of small industrial boiler fired by coal is only around 67%, about 25% of heat is discharged into atmosphere directly along with flue gas, exhaust temperature is even higher than 200℃. Boiler efficiency will rise 1% when exhaust temperature goes down every 15-18%. Reducing flue gas temperature is an important way to save energy. So, for large capacity boiler, an economizer with serpentine tube is used to preheat boiler feedwater by the heat recovered from hot flue gas. Although traditional economizer improves boiler efficiency to a higher level, it is not suitable for small scale industrial boiler. Heat pipe economizer is a better option.

 

 

 

Heat pipe economizer structure

 

Heat pipe economizer is invented as flue gas heat exchanger for generation of hot water, especially for cases where flue gas desulfurization is required. Water spraying is used to cool down flue gas because hot temperature is bad for FGD performance. In this case, heat pipe economizer could not only reduce flue gas temperature, but also produce hot water.

 

Heat pipe economizer consists of heat pipe, framework, header, casing, etc. Cold water passes through upper section, while hot flue gas passes through lower section. Working fluid transfers heat from one point to another by cyclical evaporation and condensation.

 

 

Features of heat pipe economizer:

 

1. Compact structure, small size, low weight, easy installation.
2. Low resistance below 300Pa.
3. High thermal efficiency. Heat pipe absorbs or releases latent heat by phase change of working fluid.
4. Good Isothermal performance. Temperature difference between hot end and cold end is within 1℃. Wall temperature of heat pipe is higher than dew point temperature.
5. Adjustable wall temperature of heat pipe by changing heat transfer area in hot & cold end.
6. Nickel based infiltrated layer on heat pipe surface to withstand corrosion.
7. Individual heat pipe. Status of heat pipe has no impact on others. Even if some of them are damaged, it will not result in mixing of hot and cold fluid, operation of whole economizer is not influenced.
8. Heat pipe is welded at one end only. It is free of stress caused by thermal expansion and contraction.
9. Heat pipe in flue gas pass is welded with spiral fins to enhance heat transfer efficiency.

 

Specification