What are the disadvantages of excessive phosphate levels in the drum water?
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Recently, a certain unit has not paid enough attention to chemical dosing in the steam drum; too much chemical was added, resulting in a phosphate level of 39. 8mg/L; please share your views on the potential hazards.
It may lead to a deterioration in steam quality and the formation of deposits in the superheater and turbine flow passages.
The salt content in the steam increases. Affects the pH value of the boiler water.
There are the following disadvantages: 1. It causes waste of phosphates. 2. If the pH level of the boiler water is too high, above 11, it may cause corrosion to the boiler tubes. 3. An increase in salts carried by the steam affects its quality, leading to scaling in equipment that uses this steam.
1. The amount of medication discharged along with the wastewater increases. 2. This leads to an increased consumption of medication. 3. It raises the salt content in the boiler water, affecting the quality of the steam. 4. It easily forms magnesium phosphate precipitates in combination with magnesium ions. 5. If the iron content in the boiler water is high, there is a risk of the formation of iron phosphate scale as well.
An increase in the salt content of the steam water may cause foaming in the steam drum.
Excessive phosphate levels not only result in waste of raw materials but also affect the lifespan of equipment; furthermore, it increases wastewater generation, leading to waste of deoxygenated water and a lower steam-to-water ratio. We also assess the steam-to-water ratio on a monthly basis – the ratio of deoxygenated water to steam should be between 1.02 and 1.05
We also evaluate the water-vapor ratio on a monthly basis; the required value for deoxygenated water per unit of steam produced is 1.02–1.05. ====================================== The evaluation of the water-vapor ratio mentioned above is referred to as water consumption per ton of steam produced. A high value indicates water waste, which is not conducive to energy savings, while a low value suggests that the processes for continuous and periodic wastewater discharge are not properly managed. Based on the values you provided, I think it’s too low. Although water is being conserved, the waste discharge rate is insufficient, and it is likely difficult to ensure the quality of the boiler water and steam. All types of boilers have requirements regarding the sludge discharge rate. In the case of industrial boilers, the water quality is often not properly treated, so this value should not be lower than 1.05; in other words, the sludge discharge rate should be around 5%. When I calculated this indicator, it was around 1.20 at first; through various measures, I managed to get it down to 1.07. In any case, I won’t go any lower than that.