The pH value issue for circulating fluidized bed boilers.
Thread Content
The 75t industrial boiler uses deionized water from a soft water station. The issue is that the pH of the deionized water is 7–8, while that of the boiler water is 9–11, and that of the steam condensate is also 7–8. In this process, only ammonia with a pH of around 11 is added to the deionized water; no other chemicals are used. What’s most confusing is that the pH level of the boiler water is significantly high; even without adding ammonia, the pH level of the boiler water still rises! Help needed.
This post was last edited by dongjiang1001 on 2012-2-9 at 17:05. The pH level of the water in your boiler is within the acceptable range; if it can be maintained without adding ammonia, then there’s no need to add any more. Additionally, the location where you are adding ammonia isn’t ideal – it’s better to add it after the deaerator’s drain pipe and before the feed pump, in the main pipeline, so that it can mix with the water driven by the pump.
The ammonia dosing point is before the water pump; the question now is why the pH value of the boiler water increases under high-temperature conditions
If the boiler feedwater is of satisfactory quality, after the boiler has been operating for some time, the concentration of certain alkaline ions in the boiler drum will increase, causing the boiler water to become alkaline and the pH value to rise as well. On the contrary, if the water hardness is not up to standard, the boiler water tends to be acidic. If the alkalinity and pH level of the water in the boiler are too high, then the volume of continuous and periodic drainage must be increased.