Descaling of coal-fired steam boilers
Thread Content
This post was last edited by sdwfsgyykai on 2016-1-30 08:44. The company currently has one coal-fired steam boiler with a capacity of 20 t/h. As the weather gets warmer and the production needs of various units increase, this coal-fired boiler has not been shut down for maintenance. There are several issues at present, and I hope experts can offer some advice: the steam output is decreasing gradually; the gas demand of the production units remains unchanged. The lowest temperature reached is -25°C, and the steam pressure has dropped from 0.8 Mpa in October to 0.35 Mpa at present. The temperature inside the furnace is around 950°C, and production can still be maintained to some extent. In my opinion, the main reason for this is that there is almost no negative pressure in the furnace, as the exhaust flue is blocked and not cleaned in time, resulting in very low air supply； The outer wall of the furnace tubes is severely coked; the sulfur content in the coal is around 1-2%. Although desulfurizing agents have been started to be used, their effects are not immediate ； Scaling on the inner wall of the furnace tubes is the most troublesome issue and one that worries me the most. For a period of time, due to damage to the reverse osmosis membranes used for water treatment, the hardness of the water supplied to the boiler remained significantly above the acceptable level (hardness of 1-3, while the normal limit is below 0.03). Although this situation lasted only for a short time, efforts were made to reduce scaling by controlling the alkalinity levels, but it’s not clear whether these measures were actually effective. I would appreciate some guidance from experts! Are there any online methods for cleaning scale?
Cleaning online at such high temperatures is somewhat difficult! I’m waiting for experts to answer!
How did I pass the annual inspection? There is too much scaling and coking.
Based on the owner’s analysis, I personally think there are three issues: 1. The problem of cleaning inside the boiler, which refers to removing scale from the interior heating surfaces of the boiler. The owner can follow the boiler’s operating instructions for cleaning it, but it is recommended to do this after shutting down the boiler. 2. External cleaning of the boiler refers mainly to the removal of slag accumulation on the outside of the boiler’s heat-exchanging surfaces. External cleaning can only be carried out manually after the boiler is shut down. 3. Cleaning and unblocking of the boiler’s smoke and air ducts; if these ducts are not properly ventilated, it will lead to fuel waste, as well as insufficient steam production and pressure – in other words, the boiler cannot deliver the required output. Summary: The first issue has an impact on the safety of the boiler; it is hoped that the original poster will take it seriously. The second and third issues will only affect the operation of the boiler; they will not have an impact on its safety in the short term. However, if used for a long time, the consequences will be...........................
Has the boiler not had its annual inspection? ? It’s really bold to still use boilers of this kind! The steam pressure has dropped from 0.8 Mpa in October to 0.35 Mpa, and the furnace temperature is around 950°C. Are there any risks associated with this? ? ?