Applications
Steam/heat differential
(Heating)
Application areas
Calculation of a steam mass circuit (mass flow) and the amount of heat contained that is then
transferred to a heat exchanger. Here the condensate contained the heat energy is taken into
account, i.e. heat energy used = heat energy up to the steam condensation plus heat energy
removed from the condensate during cooling.
Measurements
Measurement of: operating volume, pressure and temperature in a steam circuit directly before a
heat exchanger (in the inflow) as well as measurement of the condensate temperature directly
after the heat exchanger (in the return).
Inputs
• Steam circuit: Super-heated steam: Flow (q), pressure (p), temperature (T
D
)
Saturated steam: Flow (q), pressure (p) or
Flow (q), temperature (T
D
)
• Condensation circuit: Temperature (T
W
)
Calculated values
• Calculation of: mass flow, heat differential (heat contents steam minus heat contents
condensate), density, specific Enthalpy, (IAPWS–IF97 Standard).
•
Only 2 inputs are required for saturated steam calculations (flow, pressure/temperature), the
missing input is calculated using the internally memorised saturated steam curves.
Note!
For higher accuracy or for control purposes, it is recommended to calculate the steam condition using 3 inputs
(super heated steam). This is recommended because in this operating mode the wet steam alarm function (see
outputs) can be used.
Output values /display at unit
• Heat flow, mass flow, flow (operating volume), temperature, pressure, density, Enthalpy
difference
• Heat quantity sum, mass sum, flow sum
Outputs
• All output values can be transmitted using the output terminals, this means both unchanged
inputs as well as calculated values. Please note that the number of outputs available is
dependent on the unit type.
• If a relay is set up for the “wet steam alarm”, this will operate as soon as the super-heated
steam reaches 2% of the saturated steam curve. An alarm message also appears in the display.
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