Evaporation Process Improvement, Service, and Training. Let me help you
Angola, New York 14006, United States
De-Superheating
Without a working De-Superheating spray
The need for de-superheating steam entering an evaporator is illustrated here in the above picture. This shows the hot zone of superheated steam which can be as high as 260 F. Generally the steam supplied will be controlled by a pressure transmitter in the steam line after the steam control valve. Remember according to the saturated steam tables, if we know the pressure we know the temperature provided the steam is saturated. The pressure selected for a set point to control the steam valve would represent the maximum temperature for the product to prevent premature fouling and burn on of the product.
If the steam is not de-superheated this hot zone will be a big problem and must be corrected.
Proper de-Superheating illustrated
Apply the correct sized spray nozzle to bring condensate into the oncoming superheated steam. This will saturate the steam and the pressure will now represent the desired temperature and be controlled to prevent the hot zone and subsequent premature fouling.
How do will know if the de-superheating is working? Compare the temperature and pressure in the steam line entering the process to the saturated steam tables and they should line up. If the temperature measured is higher than the steam pressure in the tables then your de-superheating system is not working. Clean the nozzle, make sure the nozzle pressure is adequate for that nozzle, and make sure it is flowing.