The Harm and Countermeasures of Boiler Scale

Tail heating surface:

(1) Equal flow velocity variable cross-section design of the tail heating surface to ensure that the minimum smoke velocity of the flag heating surface is more than 6m/s.

(2) The tail heating surface of each stage is reserved for soot blower interface and installation of soot blower.

Air preheater:

(1)The smoke speed of air preheater shall be guaranteed to be 10 ~ 12 m/s.

(2)Using of large diameter pipes to prevent ash blockage.

1. Waste fuel and reduce boiler thermal efficiency

Because the thermal conductivity of scale is tens to hundreds of times higher than that of steel. Therefore, when the boiler has 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 taken away by the flue gas, resulting in an increase in exhaust temperature, an increase in exhaust 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 estimate that there is a 1mm thick scale on the heating surface of the boiler, which wastes about 3% to 5% of the fuel.

2. Impact on the safe operation of the boiler

Boiler scale is often generated 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 significantly increases. When the temperature exceeds the allowable temperature that the metal can withstand, the metal creeps due to overheating and its strength decreases. Under the working pressure of the boiler, the metal will experience bulging, perforation, and fracture, which affects the safe operation of the boiler.

3. Scale can cause metal corrosion under the scale

Under the condition of scale adhering to the heating surface of the boiler, the boiler water that seeps into the pores and gaps of the scale rapidly evaporates 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 serious corrosion to the heating surface of the boiler under high temperature and concentration conditions. The mutual promotion of scaling and corrosion processes can quickly lead to damage to the metal heating surface, leading to boiler tube explosion accidents.

4. Reduce boiler output

After boiler scaling, due to poor heat transfer, it needs to consume more fuel to reach the rated evaporation or rated heat production of the boiler. But as the thickness of fouling increases and the grate area of the furnace volume is fixed, fuel consumption is limited, so the output of the boiler will decrease.

5. Scaling will reduce the service life of the boiler

The scale on the heating surface of the boiler must be thoroughly removed to ensure safe and economical operation. Whether manual, mechanical, or chemical descaling is used, 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 softened water treatment equipment to protect the boiler. At the same time, it is necessary to regularly inspect the boiler to ensure its normal operation.

The above is Jiangsu Sifang Clean Energy Equipment Manufacturing's answer to this question. If you have any questions about other boiler related issues, please consult Jiangsu Sifang Clean Energy Equipment Manufacturing's online customer service or call 0516-85532690. Jiangsu Sifang Clean Energy Equipment Manufacturing's professional technicians will answer your questions in time.