Water quality regulation in the drum
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Sea friends, I really can’t deal with this anymore. Specifically, the phosphate content in the water of the 1.0 MPa drum in our atmospheric and vacuum distillation unit is quite puzzling. For about 2 weeks, the phosphate level remained at only 0-3 mg/L. We then continued to add phosphate – initially using 4 KG of trisodium phosphate together with 1.5 KG of sodium hydroxide, with a dosing rate of 40 liters per hour. Yet the phosphate level didn’t increase; even when the amount of trisodium phosphate used was increased to 5.5 KG along with 1.5 KG of sodium hydroxide and the dosing rate was set at 100%, the phosphate level was still around 2 mg/L. This concentration remained unchanged for about 5 or 6 days, with the phosphate level staying very low throughout that time. Then, one day suddenly, the phosphate level soared to 60+ mg/l, and sometimes it even reached over 100. . . . . ), that’s the case with phosphate levels – they fluctuate outside the range of 10-30, either being very low or extremely high. . . . By the way, our steam generation is stable at 8 t/h. The feedwater and drum liquid levels don’t pose any issues; the feedwater flow rate fluctuates frequently between 5–9 T/h. The liquid levels are regulated automatically based on the feedwater flow, but they still keep fluctuating, remaining within the range of 55–65%. . . . Dear sea friends, please give me some advice. . . . .
I would like to add a few more points for reference: 1. Adjusting the quality of water and steam in the boiler system is a relatively long-term process, or it must be such a process; otherwise, there will be significant fluctuations, similar to the lag in PID control. 2. The variation in sulfate levels is closely related to the amount of chemical added and the amount of wastewater discharged; if these levels are too low, the usual approach is to increase the amount of chemical added appropriately. After an increase is made, it is necessary to allow the levels to stabilize for a while. If you wait until the quality meets the standards, the phosphate content in the boiler water will increase sharply thereafter. So this is what I mentioned in the first point: it must be a long process; otherwise, it’s like running back and forth. 3. Additionally, in most cases, adding trisodium phosphate can be used to adjust the pH as well as to regulate the level of phosphates, while sodium hydroxide is generally used only as a means to adjust the pH. Provided that the pH is within the acceptable range, generally only trisodium phosphate needs to be added. If the phosphate level is within the acceptable range but the pH is not, an appropriate amount of sodium hydroxide can be added. 4. Speaking of waste discharge, continuous discharge is a continuous process, and adjustments must be made on a small scale. Regular drainage is primarily used to remove the sedimentary impurities inside the boiler, and it is necessary to control the frequency and duration of this process. 5. If the steam generation remains stable, the entire boiler system should be relatively stable as well. The fluctuations in your liquid level are quite significant; these can be adjusted by fine-tuning the PID settings. Here, under normal circumstances, the boiler liquid level fluctuates within plus or minus 2%. Even if there are fluctuations, it can return to normal with just about three waves.