How should the process parameters be controlled after adding a flash heater?
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It is understood that in many aqueous urea production plants, in order to save steam, a heater is installed below the flash tank to reduce the loading on the first and second evaporation stages. However, please take into account the operation status of your own equipment or the information you have available, and explain how to control the process parameters after installing a flash heater (Vaporizer outlet liquid, vaporizer vacuum level, etc.)
This post was last edited by Xieshui on 2009-9-19 at 21:01. The original poster: Not only is this approach used in water-based urine treatment, but many large-scale CO2 stripping systems also employ it to increase their production capacity (1800–2200 tons per day); this is known as pre-evaporation or preliminary evaporation. As for the temperature and vacuum levels, these depend first on the heat source and second on the desired concentration. Generally, the concentration should not be too high, as this can lead to side reactions and crystallization issues. Here, the concentration is controlled at 80–85%, the temperature around 105 degrees, and the vacuum level can be determined by referring to the phase diagram of “urea–water”. This method reduces the load on the first and second stages; no changes are needed to the equipment in those stages, yet the production capacity increases.
Dear Xishui Haiyou: Does your urea production plant have a flash heater installed? If so, is the outlet liquid temperature of your flash tank set at 105°C? Has the corresponding urine concentration been analyzed?
May I ask, if a flash heater is added, is it necessary to add a flash condenser as well?
Flash heater, flash condenser, flash separator. Our company controls the flash vacuum at 50 MMHg; the current temperature is set at 104 degrees. Valves are installed before and after the flash condenser to control the inflow and outflow of gas in both directions.