What are the reasons for the insufficient vacuum level in the evaporation system? (CO2 stripping method)

The free ammonia level is high, the steam pressure for pressure increase is low, the urine concentration is relatively low, and the pressure difference between stage 1 and stage 2 is low. If a vacuum cannot be created in stage 2, the pressure booster can be used; however, the ammonia tank might fill up quite quickly

1. Excessive evaporation load. 2. High levels of free ammonia in the urine or low urine concentration. 3. Low steam pressure in the jet pump. 4. Poor condensation of secondary steam in the surface cooler (high temperature of the circulating water, presence of inert gases, etc.). 5. Leaks in equipment and pipelines. 6. Too low a liquid level in the ammonia tank, resulting in no water seal. 7. Problems with the instruments. 8. Issues with the flushing valves, which may not be closed properly, as well as problems with the various water addition valves. 9. Crystallization in the pressure guiding tubes, as well as crystalline blockages in the throat tubes and separators (these can be resolved by cleaning)

I’d also like to mention the main reasons: 1. High circulation pressure leads to incomplete decomposition in the distillation tower, which increases the load on the evaporation system; furthermore, it causes the liquid seal at the outlet of the distillation tower to fail, resulting in gas leakage； 2. The pressure gauge’s pressure transfer tube is blocked, causing problems with the gauge ； 3. Insufficient steam pressure (with water) ； 4. The evaporation system has a leak ； 5. Low urine concentration, resulting in a decrease in the concentration after washing and recovery ； 6. High circulating water temperature, resulting in poor surface cooling effect ； 7. Poor gas flow in the evaporator, poor gas flow in the evaporation condenser, poor gas flow in the surface cooler, and so on ； 8. High levels of free NH3 in urine ； 9. The evaporation amount is set too high, resulting in excessive load ； 10. Leakage from the water inlet valve of the urine pump ； 11. The flash condenser has poor condensing efficiency; crystallization of the liquid at the bottom of the flash condenser causes blockages, and accumulation of liquid occurs in the evaporation condenser and surface coolers. 12. Circulating water supply is interrupted, or pressure drops ； 13. Problems with the steam ejector pump nozzles, which prevent it from meeting vacuum pumping requirements ； This is just a simple list; in actual production, there may be other situations as well. For example, if the steam used for purging the gas phase in the flash condenser is not completely turned off, it could also prevent a vacuum from being established.