Scale directly threatens the safety and service life of the steam generator device because the thermal conductivity of scale is very small. The thermal conductivity of scale is hundreds of times smaller than that of metal. Therefore, even if not too thick scale is formed on the heating surface, the heat conduction efficiency will be reduced due to the large thermal resistance, resulting in heat loss and waste of fuel.
Practice has proved that 1mm of scale on the heating surface of the steam generator can increase coal consumption by about 1.5~2%. Due to the scale on the heating surface, the metal pipe wall will be partially overheated. When the wall temperature exceeds the allowable operating limit temperature, the pipe will bulge, which may seriously cause a pipe explosion accident and threaten personal safety. Scale is a complex salt containing halogen ions that corrodes iron at high temperatures.
Through the analysis of iron scale, it can be seen that its iron content is about 20~30%. Scale erosion of metal will cause the inner wall of the steam generator to become brittle and corrode deeper. Because removing scale requires shutting down the furnace, it consumes manpower and material resources, and causes mechanical damage and chemical corrosion.
The Nobeth steam generator has an automatic scale monitoring and alarm device. It measures the scaling on the pipe wall by monitoring the exhaust temperature of the body. When there is slight scaling inside the boiler, it will automatically alarm. When the scaling is severe, it will be forced to shut down to avoid scaling. The risk of pipe bursting better extends the service life of the equipment.
1. Mechanical descaling method
When there is scale or slag in the furnace, drain the furnace water after shutting down the furnace to cool the steam generator, then flush it with water or use a spiral wire brush to remove it. If the scale is very hard, it can be cleaned with a pipe pig driven by high-pressure water jet cleaning or hydraulic power. This method is only suitable for cleaning steel pipes and is not suitable for cleaning copper pipes because the pipe cleaner can easily damage the copper pipes.
2. Conventional chemical scale removal method
According to the material of the equipment, choose a safe and powerful descaling cleaning agent. Generally, the solution concentration is controlled to 5~20%, which can also be determined according to the thickness of the scale. After cleaning, first release the waste liquid, then rinse with clean water, then fill up the water, add a neutralizer with about 3% of the water capacity, soak and boil for 0.51 hours, after releasing the residual liquid, rinse once or twice with clean water.
Scale build-up in the steam generator is very dangerous. Regular drainage and descaling is required to ensure the normal operation of the steam generator.
Post time: Nov-08-2023
