Steam & Condensate Introduction
Steam Trap Installed after a Control Valve ... which can cause wide variations of trap inlet pressures and condensate loads.
The flow rate and the steam pressure in the jacketed kettle is determined by the temperature control valve. When the process fluid in the jacketed kettle reaches the desired set temperature, the control valve reduces the flow of steam which, in turn, reduces steam pressure. The Steam pressure can drop down to 0 psig or below (to sub-atmospheric pressures) to maintain just the correct amount of steam flow to keep the kettle at the exact set temperature. With the varying amount of steam that is sent to the process, the amount of condensate that is generated also varies. If the steam demand is high for a given period, more condensate is generated after the steam is used. When there is a low steam demand, less condensate is generated. The appropriate steam trap selected for process applications must be able to adjust to varying condensate loads without oversizing, and have the capability to remove air from the system.
The Control Valve regulates the amount of Steam delivered to the process equipment
Temperature Controller
50 psig
Flash Steam
Temp Sensor
30 psig
30 psig
Steam Pressure pushes condensate through the steam trap
0 psig
2.3 FT.
Flash Steam
0 psig
F&T Trap
Vented Receiver A Vented Receiver maintains a pressure of 0 psig inside the condensate return lines by venting the flash
Hot Condensate
Inlet Pressure (Steam)
Outlet Pressure (Condensate)
–
=
Differential Pressure
steam generated by the hot condensate to the atmosphere
30 psig
–
0psig
= 30 psi
Pump
Why the Steam Trap needs to be placed a minimum distance below Jacketed Kettle
0 psig
When set temperature of the process fluid is reached, the steam pressure inside the jacketed kettle may reduce to 0 PSIG or even go into Vacuum. To promote condensate drainage, the steam trap is placed a certain distance below the process equipment. 2.3 ft. will provide 1 psig of condensate head pressure. As long as the trap discharges into a gravity return line (at 0 psig), there will be 1 psi differential pressure and condensate may freely drain. Pressure = Column Height x 0.433 psi ft 1 psig = 2.31 Ft. x 0.433
Inlet 1 psig
1 psig
2.31 ft. water column
2.3 ft.
2.31 Ft. X 0.433 = 1 psig
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