Carbon Steel Boiler Economizer Bank High Heat Transfer Of H Fin Tubes Anti Corrosion

High Heat Transfer Carbon Steel Boiler Economizer bank of H Fin Tubes Anti-Corrosion

Economizer Functions

H-type finned tube heat exchanger elements maintain a high capacity for heat transfer, possess superior self-cleaning properties and retain the ability to effect flue gas waste heat recovery in boiler renovations. Convective heat transfer coefficient is proportional to fin pitch, but inversely proportional to fin height and fin width. Integrated heat transfer capacity is related to fin efficiency, convective heat transfer coefficient and finned ratio. Pressure drop increases with the increase of fin height and fin width.
The primary effect of economizer is to absorb waste heat of flue gas to heat boiler water supply, reduce smoke exhaust temperature and advance boiler thermal efficiency. Feed water temperature forward and backward into the drum, reduce the temperature difference between the water pipe and the drum wall, thus reducing the thermal stress of the drum wall, is conducive to prolong the service life of the drum. In addition, the water supply is heated in the economizer before entering the transpiration heating surface, reducing the heat absorption of water in the transpiration heating surface, which is equivalent to replacing some of the transpiration heating surface with the economizer. The cost of economizer heating surface is much lower than that of transpiration heating surface. Therefore, it is economical to install economizer from the perspective of boiler manufacturing economy.

Economizer Types
If according to materials, economizers can be divided into steel tube economizers and iron economizers. At present, most large and medium volume boilers widely use steel tube made economizers, because they have high strength and reliable working ability, and are able to withstand impacts, meanwhile they have good performance of heat transfer, small structure and low cost. One weak point is bad corrusion resistance, but now the modern boiler feed water are strictly treated, so the problem is almost solved.
If according to heating extension of the working fluid, economizers can be divided into non-boiling and boiling types.
1. Boiling economizers: the outlet water temperature not only can reach the surnatured temperature, but also can make some water vapourized, the proportion is about 10-15% of total feed water, not more than 20% in case of much flow resistance caused to the working fluid.
2. Non-boiling economizers: the outlet temperature is 20-25 degrees lower than the boiling point under pressure given.
Most of medium-presssure boilers use boiling type economizers. This is because the latent heat of vaporization of water in medium-pressure boilers is high, and the heat of the heated water is smal. Thus it is necessary to send some water to be vaporized in boiler economizer so as to prevent unstable combusion in funaces and prevent increased consumption of metal in the heating surfaces as superheaters caused by too low outlet flue gas temperature. In addition, it can help to play the role of economizers.
Superhigh pressure boilers mostly use non-boiling type economizers. This is because when the pressure is higher, the latent heat of vaporization is decreased, while heat of the heated water is getting more, so it is necessary to send some water to be heated in water wall panels so as to prevent the slagging on the heating surfaces of the furnace outlets and the furnace inside caused by too high temperatures in furnaces and of outlet flue gas. So usually superhigh pressure boilers use non-boiling type economizers.
The main factor to consider which type of economizers is boiler's parameters. When the boiler parameters differ, the ratio of heat absorption needed in three stages to heat the working fluid make differences. So the corresponding arrangements of three heating surfaces need to change, too. To large units with high parameters, their evaporative heat absorption is less, while the heat absorption of water by heating, the heat absorption of steam by superheating, the heat absorption by reheating are quite big. Thus, non-boiling type economizers are the main type for superhigh pressure unit boilers.

Specifications

Quality Control

1. Impact test and Strength calculation report with applied materials information.
2. 100%NDT(non-destructive inspection) report of steel plate, tube and electrode
3. X-ray, γ-ray and liquid penetrant test inspection report (welding seam): to ensure the quality of the entire boiler
4. Hydraulic test report: ensure the standard working pressure and safety