Carbon Steel/Stainless Steel Economizer Module with Manifold Header For Coal-fired Boilers

Carbon Steel/Stainless Steel Economizer Module with Manifold Header For Coal-fired Boilers

Summary
There are three stages from the feed water in the boiler heated into superheated steam:feed water preheating, evaporation, and superheating. The three stages are finished on three different heating surfaces. The boiler steam and water circuit are composed of the three different heating surfaces as well as their connecting pipes. Boiler economizers are one of them, and it is right the equipment to preheat the feed water. Thus, it is the heating surface with the lowest temperature for boiler working fluid in the boiler steam and water circuit. The working fluid passing through this equipment is monophasic water(non-boiling economizer).

Functions

The origin to use economizers is to heat the feed water using flue gas waster heat so as to decrease the exhaust temperature and increase boiler efficiency, save fuel consumption, which is how economizer is named. If use boiler economizers, the feed water is already heated here before coming to evaporation heating surface, thus the heat absorted on evaporation heating surface as well as the heating area is definitely decreased. Boiler economizers are countercurrent placed. The working fluid average temperature is lower than that of surnatured water, and apply mandatory flow to create conditions for application of thin wall and small diameter tubes. The whole structure is also very tight. Thus, the heat transfer temperature difference and heat transfer co-efficient is higher than that of convection evaporation tube bundle who has the same smoke temperature range. That boiler economizers to replace convection evaporation tube bundles can decrease metal consumption by a large extend. Further more, the heated feed water comes to steam drum, this way can decrease the temperature difference between the water and the steam drum wall, and ultimately decrease the thermal stress of the steam drum. Due to reasons above, now economizer are the crutial parts of boilers. So we can summerize the functions of economizers as below:

1. fuel saving: the economizers are placed at the rear part of boilers. This way can decrease the smoke and gas temperatures, thus to save fuels.

2.improve the working conditions of steam drums: due to economizers, the feed water temperature is increased when entering the steam drum. It reduces the temperature difference between the feed water and steam drum wall as well as steam drum thermal stress, so that it improve the working conditions of steam drums and increase the service life.

3.reduce the boiler manufacturing cost: for the feed water is heated in the boiler economizers. The use of low temperature spare parts as boiler economizers to replace some of high-priced high temperature water wall panels reduces the cost to manufacture boilers.

Working principle

Boiler economizer is kind of heat exchanger to heat the feed water using the flue gas heat. The flue gas coming from the tube outside is up and down cross-flow scrubbing the tube bundle, passing the heat to the tube wall. The water is flowing from bottom to top, and absorts the heat from the tube wall, and its temperature is getting high. This way not only can countercurrent heat transfer to save metal consumption, but also is good for water/steam to flow and exhaust as well as decreasing corrusion. One more, this way works well for dust cleaning.

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