The WNS oil-fired gas boiler adopts a horizontal three-pass wet-back structure. The internal water of the boiler reports fire, the heating area is large, and the heat exchange effect is good. So, what is a wet back boiler and what are its characteristics? The steam boiler runs for a long time and needs to be cleaned. What are the cleaning methods for the boiler? Zozen Boilers will give you a detailed introduction.
"Wet-back" boiler means that the flue gas chamber of the boiler is moved into the barrel of the corresponding boiler model. The tube plate, back plate and cylinder of the flue gas chamber are all surrounded by boiler water (that is, immersed in the boiler water), so it is called "Wet back type" (also called water back type).
After the flue gas of this type of steam boiler enters the human smoke pipe (the first return smoke pipe) through the transfer smoke chamber, the temperature of the smoke is already low when it reaches the front smoke box (usually about 450 ℃), which makes the structure of the front smoke box manufactured It becomes simple, generally use a steel structure lined with thermal insulation material. The "wet-back" structure not only can adapt to high temperatures, has good airtightness, and its volume is much smaller than that of the "dry-back" smoke transfer chamber. Therefore, the shortcomings of the "dry back" structure can be avoided, the normal operation period of the boiler can be extended, and the maintenance cost can be reduced, so it has been widely used.
Cleaning method of wet back steam boiler
1. Water treatment outside the pot----lime + soda ash softening method:
This method is applicable to various boilers. At present, the effect of water treatment outside the pot is reliable. During boiler operation, avoid water shortage in the boiler. The lime + soda ash softening method is to add a proper amount of quicklime and soda ash to the clarified water to achieve the purpose. There are two softening methods of lime + soda ash: cold method and hot method. The cold treatment is performed at room temperature to reduce the residual hardness in the water to 1.5 to 2 meq/l. The thermal method is to heat the water to 20-80°C to reduce the residual hardness in the water to 0.3-0.4meq/L.
Therefore, thermal methods should be used as much as possible to improve the softening effect. The ion exchange softening method mainly relies on the softening treatment of the exchange resin in the sodium ion exchanger. Due to the strong adsorption capacity of the exchange resin, it can adsorb free calcium and magnesium ions in the water, so that the hardness of the boiler feed water reaches the qualified standard. There are two major types of ion exchangers, inorganic and organic. Inorganic exchange resins can only be used for surface exchange, with poor softening effect and less use. The organic exchange resin is characterized in that the core structure of the particles is loose, and the exchange reaction can be carried out on the surface and inside of the particles at the same time, and the softening effect is good, so it is used more.
2. Water treatment in the pot----adding chemical reagents:
This method is mainly to add chemicals to the boiler water to form loose sediments. Calcium and magnesium salts form scale in the boiler water, and then discharge the sediments out of the furnace through sewage discharge, thereby preventing (or reducing) boiler fouling. The furnace chemical water treatment is generally used in small low-pressure fire tube boilers. The commonly used drugs in pot water treatment are: trisodium phosphate, sodium carbonate (soda), sodium hydroxide (such as caustic soda, also known as caustic soda) and organic colloid (silica gel).
When adding medicines, various medicines should be prepared into a solution first, and then added to the pot. Generally, the solution concentration of trisodium phosphate is 5 to 8%, the solution concentration of sodium carbonate is not more than 5%, and the concentration of sodium hydroxide is not more than 1 to 2%. Both quantitative and continuous dosing can be used in the 1653 dosing method. The regular dosing mainly relies on the metering tank for dosing; the water is continuously added before the watering device. For steam boilers, it is better to use a continuous metering method to keep the liquid in the furnace uniform. Anyone who uses water treatment in the boiler should strengthen the boiler discharge, so that the formed sludge and mud can be discharged out of the furnace, and good results have been achieved.
The above introduces the cleaning methods of wet back boilers and wet back steam boilers. When using industrial boilers, attention should be paid to adopting scientific and reasonable operation methods, and the boiler should be maintained regularly, and the water quality should be tested to ensure the operation effect and service life of the boiler.
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