The three effect evaporative crystallizer is suitable for the evaporation and crystallization of solutions with crystal precipitation, and is widely used in the chemical industry, metal mining smelting, acid washing waste liquid of large steel mills, wet desulfurization waste liquid treatment of power plants, etc. (sodium chloride, phenylpropanoic acid, sodium sulfate, ammonium chloride, glycine; barium chloride, zinc sulfate, calcium chloride, ammonium sulfate, sodium hydroxide).
Common faults and solutions of three effect evaporative crystallizer:
1、 Abnormal vacuum degree
1. Vacuum too low
Phenomenon: The temperature of the secondary steam increases, the evaporation rate decreases, and the boiling point of the material loses control.
Reason:
Insufficient cooling water or high temperature (>35 ℃), resulting in insufficient condensation of secondary steam;
Equipment sealing failure (flange, weld leakage) or vacuum pump failure;
Excessive steam pressure (>0.4MPa) increases the load on the cooling system.
Solution:
Check the blockage of cooling water valves and pipelines to ensure a flow rate of ≥ 3m ³/h;
Use soapy water to detect leaks and tighten the seals. If necessary, replace the vacuum pump seal ring;
Adjust the steam pressure reducing valve to a stable range of 0.2-0.3MPa.
2. Vacuum too high
Phenomenon: Sudden decrease in evaporation and increase in steam consumption.
Reason: The cooling water temperature is too low (<15 ℃) or the steam supply is insufficient.
Solution: Adjust the temperature of the cooling water mixing valve to 20-25 ℃ and check the pressure of the steam pipeline.
2、 Decreased evaporation efficiency
1. Scaling blockage
Phenomenon: The heat transfer coefficient decreases, and the evaporation rate decreases by more than 50%.
Reason: High salt materials crystallize and deposit on the heating tube wall (such as CaSO ₄ NaCl)。
Solution:
Perform acid washing every 72 hours (5% citric acid cycle for 2 hours);
Upgrade anti scaling materials (such as titanium alloy heating tubes) or add scale inhibitors.
2. Condensation water backflow
Phenomenon: Water enters the vacuum system and the material is diluted.
Reason: The vacuum pump stopped and did not destroy the vacuum in a timely manner, or the condensate pipe was blocked.
Solution:
Urgently close the steam valve, drain the condensed water, and then restart;
Install check valves and regularly clean the condenser scale.
3、 Mechanical malfunction
1. Pump body vibration/abnormal noise
Reason: Corrosion or cavitation of axial flow pump impeller, insufficient cooling of mechanical seal.
Solution:
• Stop the machine and replace the corrosion-resistant impeller (such as Hastelloy material);
Ensure that the sealing cooling water pressure is ≥ 0.4MPa.
2. Leakage accident
High risk points: flange gaskets, expansion joints, welds.
Prevention:
Conduct a 0.3MPa air pressure leak test and regular ultrasonic thickness measurement before driving;
High temperature pipelines use corrugated pipes to compensate for thermal stress.