WNS oil-fired gas boilers use a horizontal three-pass wet back structure. The water inside the boiler reports the 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? Steam boilers run for a long time and need to be cleaned. What are the cleaning methods for boilers?
1. Wet back boilers
1. "Wet back" boilers refer to boilers whose smoke chambers are moved into the drum of the corresponding boiler model. The tube plates, back plates and drums of the smoke chambers are surrounded by boiler water (i.e. immersed in boiler water), so they are called "wet back" (also called water back).
Advantages of "wet back" structure boilers:
2. Advantages of "wet back" boilers:
After the flue gas enters the smoke pipe (first return smoke pipe) through the smoke chamber for heat exchange, the smoke temperature is already low when it reaches the front smoke box (generally around 450℃), making the structural manufacturing of the front smoke box simple, and generally a steel structure lined with insulation material can be used.
The "wet back" structure can adapt to high temperatures, has good sealing, and its volume is much smaller than that of the "dry back" smoke chamber. Therefore, it can avoid the shortcomings of the "dry back" structure, extend the normal operation cycle of the boiler, and reduce maintenance costs, so it is widely used.
2. Wet back steam boiler cleaning method
1. Water treatment outside the boiler-lime + soda ash softening method
This method is suitable for various boilers. At present, the effect of water treatment outside the boiler is reliable. During boiler operation, it is necessary to avoid boiler water shortage. The lime + soda ash softening method is to add an appropriate amount of quicklime and soda ash to the clarified water to achieve the purpose. There are two types of lime + soda ash softening methods: cold method and hot method. Cold treatment is carried out at room temperature to reduce the residual hardness in the water to 1.5 to 2meq/l. The hot 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, hot methods should be used as much as possible to improve the softening effect. The ion exchange softening method mainly relies on the exchange resin in the sodium ion exchanger for softening treatment. 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 meets the qualified standard. There are two major categories of ion exchangers, inorganic and organic. Inorganic exchange resins can only perform surface exchange, with poor softening effect and are used less. The characteristic of organic exchange resins is that the core structure of the particles is loose, and the exchange reaction can be carried out simultaneously on the surface and inside of the particles, and the softening effect is good, so it is used more.
2. Boiler water treatment-adding chemical reagents
This method mainly adds chemical substances to the boiler water to form loose precipitates, calcium salts and magnesium salts form scale in the boiler water, and then discharges the precipitates out of the furnace through sewage discharge, thereby preventing (or reducing) boiler scaling. Boiler water treatment is generally used for small low-pressure fire tube boilers.
Commonly used drugs in boiler water treatment are: trisodium phosphate, sodium carbonate (soda), sodium hydroxide (such as caustic soda, also known as caustic soda) and organic colloids (silica gel).
When adding drugs, various drugs should be prepared into solutions 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 quantitative feeding can use quantitative dosing methods. Regular dosing mainly relies on metering tanks for quantitative feeding; it is continuously added to the water before the watering device. For steam boilers, it is better to use continuous metering methods to keep the liquid in the furnace uniform. Anyone who uses water treatment in the pot should strengthen the boiler discharge so that the sludge and dirt formed are 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, it is necessary to pay attention to the use of scientific and reasonable operating methods, and regularly maintain the boilers, test the water quality, and ensure the operation effect and service life of the boilers.
WNS oil-fired gas boilers use a horizontal three-pass wet back structure. The water inside the boiler reports the 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? Steam boilers run for a long time and need to be cleaned. What are the cleaning methods for boilers?
1. Wet back boilers
1. "Wet back" boilers refer to boilers whose smoke chambers are moved into the drum of the corresponding boiler model. The tube plates, back plates and drums of the smoke chambers are surrounded by boiler water (i.e. immersed in boiler water), so they are called "wet back" (also called water back).
Advantages of "wet back" structure boilers:
2. Advantages of "wet back" boilers:
After the flue gas enters the smoke pipe (first return smoke pipe) through the smoke chamber for heat exchange, the smoke temperature is already low when it reaches the front smoke box (generally around 450℃), making the structural manufacturing of the front smoke box simple, and generally a steel structure lined with insulation material can be used.
The "wet back" structure can adapt to high temperatures, has good sealing, and its volume is much smaller than that of the "dry back" smoke chamber. Therefore, it can avoid the shortcomings of the "dry back" structure, extend the normal operation cycle of the boiler, and reduce maintenance costs, so it is widely used.
2. Wet back steam boiler cleaning method
1. Water treatment outside the boiler-lime + soda ash softening method
This method is suitable for various boilers. At present, the effect of water treatment outside the boiler is reliable. During boiler operation, it is necessary to avoid boiler water shortage. The lime + soda ash softening method is to add an appropriate amount of quicklime and soda ash to the clarified water to achieve the purpose. There are two types of lime + soda ash softening methods: cold method and hot method. Cold treatment is carried out at room temperature to reduce the residual hardness in the water to 1.5 to 2meq/l. The hot 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, hot methods should be used as much as possible to improve the softening effect. The ion exchange softening method mainly relies on the exchange resin in the sodium ion exchanger for softening treatment. 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 meets the qualified standard. There are two major categories of ion exchangers, inorganic and organic. Inorganic exchange resins can only perform surface exchange, with poor softening effect and are used less. The characteristic of organic exchange resins is that the core structure of the particles is loose, and the exchange reaction can be carried out simultaneously on the surface and inside of the particles, and the softening effect is good, so it is used more.
2. Boiler water treatment-adding chemical reagents
This method mainly adds chemical substances to the boiler water to form loose precipitates, calcium salts and magnesium salts form scale in the boiler water, and then discharges the precipitates out of the furnace through sewage discharge, thereby preventing (or reducing) boiler scaling. Boiler water treatment is generally used for small low-pressure fire tube boilers.
Commonly used drugs in boiler water treatment are: trisodium phosphate, sodium carbonate (soda), sodium hydroxide (such as caustic soda, also known as caustic soda) and organic colloids (silica gel).
When adding drugs, various drugs should be prepared into solutions 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 quantitative feeding can use quantitative dosing methods. Regular dosing mainly relies on metering tanks for quantitative feeding; it is continuously added to the water before the watering device. For steam boilers, it is better to use continuous metering methods to keep the liquid in the furnace uniform. Anyone who uses water treatment in the pot should strengthen the boiler discharge so that the sludge and dirt formed are 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, it is necessary to pay attention to the use of scientific and reasonable operating methods, and regularly maintain the boilers, test the water quality, and ensure the operation effect and service life of the boilers.