The hazards and countermeasures of boiler scale
The hazards and countermeasures of boiler scale
1. Waste fuel and reduce boiler thermal efficiency
Because the thermal conductivity of scale is tens to hundreds of times lower than that of steel. Therefore, when the boiler forms scale, the heat transfer performance of the heating surface of the boiler deteriorates, and the heat released by fuel combustion cannot be effectively transferred to the boiler water. A large amount of heat is carried away by the flue gas, resulting in an increase in exhaust gas temperature, an increase in exhaust gas heat loss, and a decrease in the thermal efficiency of the boiler. In this case, in order to ensure the parameters of the boiler, more fuel must be added to increase the temperature of the furnace and flue gas, resulting in fuel waste. Some people estimate that there is a 1mm thick scale on the heating surface of the boiler, which wastes about 3% to 5% of fuel.
2. Affects the safe operation of boilers
Boiler scale often forms on the heating surface of boilers with high heat loads. Due to the poor thermal conductivity of scale, the local temperature of the metal pipe wall increases significantly. When the temperature exceeds the allowable temperature that the metal can withstand, the metal will creep due to overheating, and its strength will decrease. Under the working pressure of the boiler, the metal will bulge, puncture, and rupture, which will affect the safe operation of the boiler.
3. Scale can cause corrosion of metals beneath the scale
Under the condition of scale adhesion on the heating surface of the boiler, the boiler water seeping into the pores and gaps of the scale evaporates rapidly between the deposited scale layer and the heating surface of the boiler. Under the scale layer, the pot water can be concentrated to a very high concentration. Some of these substances, such as NaOH, can cause severe corrosion to the heating surface of boilers under high temperature and concentration conditions. The processes of scaling and corrosion mutually promote each other, which can quickly cause damage to the metal heating surface, leading to boiler tube bursting accidents.
4. Reduce boiler output
After boiler scaling, due to the deterioration of heat transfer, it is necessary to consume more fuel to achieve the rated evaporation capacity or rated heat generation of the boiler. But as the thickness of scaling increases and the grate area of the furnace volume remains constant, fuel consumption is limited, resulting in a decrease in boiler output.
5. Scaling will reduce the service life of boilers
The scale on the heating surface of the boiler must be thoroughly removed to ensure safe and economical operation of the boiler. Whether it is manual, mechanical, or chemical descaling, it will affect the service life of the boiler.
In summary, the harm of boiler scale is enormous, and reducing the problem of boiler scale must be our main concern. To remove scale, we must first reduce the hardness of the water. We can choose a set of boiler softening water treatment equipment to protect the boiler. At the same time, it is necessary to regularly inspect the boiler to ensure its normal operation.