|Place of Origin:||Jiangsu , China|
|Model Number:||Superheater and Reheater|
|Minimum Order Quantity:||1 Set|
|Delivery Time:||30 days after deposit|
|Payment Terms:||L/C, T/T|
|Supply Ability:||500 Tons per Month|
|Structure:||Electric Elements||Pressure:||Low/High Pressure|
|Color:||Red / Blue / Grey||Material:||Carbon Steel|
|Usage:||Power Plant/CFB Boiler|
Steel Tube Boiler Economizer for Thermal Power Station Boilers with Natural Circulation
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).
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.
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.
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.
The structure of boiler economizers
No matter it is boiling or non-boiling type, their structures are the same. They are made of horizontal surpentine pipes, with inlet and outlet headers in parallel. The connection of surpentine pipes and headers are usually finished by welding. Headers are generally places outside of boiler's flue system. If there are lots of heating surfaces in economizer, the general height is quite high. We can divide them into several sections. Shown in picture 3-1, it is divided into two sections, each height is about 1-1.5m, their distance is 0.6-0.8m as overhaul room. In addition, it is needed to set aside 0.8-1m of space for overhaul and clearance of accumulated dust on the heating surfaces.
|Material||Alloy steel, Carbon steel, SA210C ,SA213T22, etc.|
|Material standard||ASTM, EN or ISO etc.|
Min: 10 ton
|Smelting Process:||EF+LF + VD|
|Process||Material→Ingot → Hot/Cold-Rolling→ Heat treatment (Normalizing+ tempering) → Inspection →rough machining→UT →2nd Heat treatment →finishing machining →Inspection|
|UT standard||ASTM A388 or EN10228, etc|
Send us required technical data, such as steam capacity, presure, required temperature etc. We will design accordingly.
Established in 1985,Zhangjiagang Hua Dong Boiler Co.,Ltd.(trading as HD Boiler),produces power plant; industrial; waste heat; waste incineration; biomass; organic heat carrier and electric steam boilers. Coupled with a comprehensive range of heating surfaces, HD Boiler brings to the market a unique service including boiler design , fabrication, installation, maintenance and replacement of boiler pressure parts.
1. Fabrication area of 200,000 square meters
2. 150 Engineers
3. 600 Coded welders
4. 60 Licensed Inspectors(NDT Level-III instructors)
5. Class-A Licenses for Design and Manufacture Boiler
6. ISO 9001:2008 Quality System
7. ASME Certificate of Power Boilers
8. ASME 'S','U' and NB stamp authorization
Contact Person: Wendy