Proline Prowirl 73 Description of device functions
Endress+Hauser 147
SELECT FLUID
(contd.)
Selected fluid: SATURATED STEAM DELTA HEAT
Prerequisite:
This option requires Prowirl 73 to read in the temperature value of an external
temperature transmitter, which is HART-enabled and set to the burst mode, via the
HART input function. For a detailed connection diagram, see ä 30
Applications:
A0001809
Calculated variables:
1. Calculation of the saturated steam mass flow and the heat withdrawn by a consumer
load, taking the energy remaining in the condensate into account.
2. Calculation of the saturated steam mass flow and the energy supplied to the
condensate in a boiler.
Formulae for calculation:
• Mass flow: m = q · (T73) (at the point of Prowirl 73)
• Delta heat: E = q · (T73) · (h (T73) – h (T2))
m = Mass flow
E = Delta heat
q = Volume flow (measured)
(T73) = Density*
h(T73) = Specific enthalpy of saturated steam*
h(T2) = Specific enthalpy of condensate*
* from water and saturated steam data as per IAPWS-IF97 (ASME) for the measured
temperatures.
!
Note!
• For this type of measurement, it is essential Prowirl 73 be located on the steam side.
• If the algebraic sign of the temperature differential changes, error message "#524 SIGN
DELTA HEAT" is displayed (ä 67).
• Prowirl 73 cannot take a change in the algebraic sign for the temperature differential
into account!
(Continued on next page)
Function description, FLOW COMPUTER group
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