Where is the phenomenon of boiler steam with water?What is the specific reason?

The phenomenon of boiler steam with water is a normal phenomenon in steam boilers.According to the provisions of JB/T10094 "General Technical Conditions for Industrial Boilers", the steam humidity of saturated steam boilers is not more than 3%, which is qualified, but the excessive amount of water must be treated.If the following phenomenon occurs, it should be caused by excessive steaming water.

The boiler feed water volume is much larger than the boiler outlet steam volume, the boiler feed water pump is fully open at the power frequency, the boiler water level continues to drop, a large amount of water flows out of the trap at the sub-drum, and the steam pipeline vibrates in severe cases.Cause analysis: ① Check whether the device in the pot (steam-water separator) is manufactured incorrectly.② Check whether the boiler water is qualified (whether the salt content of the boiler water exceeds the standard).③ Check the operation record of the boiler and understand the steam usage of the owner, whether there is excessive fluctuation in the compliance of steam usage and sudden surge in load.④Whether the water level of the boiler is normal, and the water level of the boiler is kept too high.Beyond the allowable variation range, the accident state false water level.2. What is the reason for the cracking of the smoke pipe of the WNSL fire tube boiler?

The cracking of the smoke pipe is generally caused by insufficient cooling of the pipe section.This problem occurs mainly due to the following three points, which need to be implemented one by one.

①The length of the pipe section protruding from the weld exceeds the standard GB/T16508 "Shell Boiler" standard. When the smoke pipe is located in the area where the smoke temperature is greater than 600 ℃, the length of the pipe end beyond the weld should not be greater than 1.5mm; when used for smoke In the area where the temperature is not higher than 600 ℃, the length of the pipe end beyond the weld can be enlarged to 5mm.For our company's products, the smoke temperature in the back combustion chamber is greater than 600 ℃, and the temperature of the front smoke box is less than 600 ℃.

② Whether the water quality is qualified Check whether there is scaling on the wall of the boiler flue pipe. The scaling causes insufficient cooling of the flue pipe by the working medium, resulting in cracking of the flue pipe.③ The pre-expansion of the smoke pipe does not meet the requirements. The smoke pipe is required to be pre-expanded before welding to eliminate the gap.If the pre-expansion of the smoke pipe does not meet the requirements, there is a gap between the wall of the smoke pipe and the tube sheet.On the one hand, there is a high residual stress in the mouth of the cigarette pipe after expansion, welding, etc., and on the other hand, there is a small gap.These crevices create capillary action that sucks in some of the boiler water, which evaporates below the height.In this way, it is continuously inhaled and evaporated, so that the free NaOH solution in the water remains in the crevice, and this concentrated solution causes alkali corrosion to the metal adjacent to the high residual stress.Corrosion cracks are intergranular corrosion, which develops from the inside to the outside. The appearance is not easy to find, there is no obvious trace of plastic deformation, and the danger is the greatest.Therefore, the pipe end is prone to cracking and leakage.