Is the ammonia nitrogen level in the purified water not up to standard?
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It is a single-tower pressurized side-line extraction process; the plant is designed for a capacity of 50 T/h. Due to the low amount of acidic water, the operation load has always been around 25 T/h. The ammonia extraction temperature in the side line is 150 degrees, with a flow rate of 4000–5000. The ammonia nitrogen content in the acidic water entering the plant is around 3000, while that in the purified water is around 50 (with a requirement of less than 60). The condensates from the first, second, and third separation tanks are returned to the raw water tank. The pressure at the top of the tower is around 4 MPa; the pressure in the first section is around 3.5 MPa at a temperature of 120 degrees, the pressure in the second section is around 3 MPa at a temperature of 90 degrees, and the pressure in the third section is around 1.5 MPa at a temperature of 40 degrees. However, the ammonia nitrogen content in the raw water tank has been increasing continuously, and it is now around 10,000. The ammonia nitrogen content in the purified water is around 100. I wonder if it’s because the amount of ammonia extracted through the side line is too large, causing a large amount of water vapor to not be properly separated in the separation tanks and thus returning to the raw water tank What actions should be taken at this stage to ensure that the purified water meets the standards? I’m a beginner; thank you all for your advice!
Reply 1# qrcl was sent by mistake! :For level L, the pressure at the top of the tower should be around 0.4 MPa; at level 1 it’s about 0.35 MPa with a temperature of 120 degrees. At level 2, the pressure is around 0.3 MPa and the temperature is 90 degrees. At level 3, the pressure is about 0.15 MPa and the temperature is 40 degrees
The side line temperature decreases, the amount of purified water sent out is too low, and the circulation volume is too high
How long has your equipment been running without maintenance? This is important. Since the operation of our 60t/h wastewater stripping unit began 7 months ago, the quality of the treated water has been excellent; the ammonia level in this water is generally around 10 only. But in the past 5 or 6 days, the purified water has had an ammonia level between 50 and 100. Our fractional condensate is added directly and as hot material enters the tower. Temperature and pressure remain unchanged from before. We are adjusting the operations, hoping for a longer operating time. Our previous 80t/h sewage treatment system required maintenance 2-4 times a year. I wonder what the operating cycle of your wastewater treatment systems is like?
Try setting the temperature and pressure for primary separation a bit higher; it’s very important to control the parameters for this stage properly!
After conducting adjusted inspections, we found that the excessive discharge of waste alkali from the amine solution purifier has a significant impact on the quality of the purified water. After the purifier was shut down for 2–3 days, the quality of the purified water gradually returned to normal.
An important aspect of the single-tower side-stream process is high-temperature water separation and low-temperature sulfur fixation; otherwise, the levels of sulfides and ammonia nitrogen in the feed water will increase, thereby affecting the quality of the purified water.
Personally, I think the side stream extraction rate and side stream temperature should be increased