KEP ES749 - 3.4 Steam Delta Heat

ES749 Flow Computer
14
3.4 Steam Delta Heat
Measurements:
Measures actual volume ow and pressure of the saturated steam in the supply piping
as well as the temperature of the condensate in the downstream piping of a heat
exchanger.
Calculations:
• Calculates density, mass ow as well as the delta heat between the saturated steam
(supply) and condensation (return) using physical characteristic tables of steam and
water stored in the ow computer.
• With square law device measurement the actual volume is calculated from the
differential pressure, taking into account temperature and pressure compensation.
• The saturated steam temperature in the supply line is calculated from the pressure
measured there.
Input Variables:
Supply: Flow and pressure (saturated steam)
Return: Temperature (condensate)
Output Results:
• Display Results
Heat, Mass or Volume Flow Rate, Resettable Total, Non-Resettable Total,
Temperature, Pressure, Density (optional: peak demand, demand last hour,
time/date stamp)
• Analog Output
Heat, Mass or Volume Flow Rate, Temperature, Pressure, Density, Peak
Demand, Demand Last Hour
• Pulse Output
Heat, Mass or Volume Total
• Relay Outputs
Heat, Mass or Volume Flow Rate , Total, Pressure, Temperature Alarms, Peak
Demand, Demand Last Hour
Applications:
Calculate the saturated steam mass ow and the heat extracted by a heat exchanger
taking into account the thermal energy remaining in the condensate.
STEAM DELTA HEAT
Delta Heat Flow
Net Heat Flow = Volume ow • density (p) • [E
D
(p)– E
W
(T)]
E
D
= Specic enthalpy of steam
E
w
= Specic enthalpy of water
Note: Assumes a closed system.
Calculations
Steam Delta Heat
Illustration
Pressure
Transmitter
Flowmeter
Temperature
Transmitter
PRINT
5
0
–
TIME
CLEAR
•
MENU
ENTER
HELP
TEMP
4
PRE 1
3
RATE
2
TOTAL
1
GRAND
6
SCROLL
7
PRE 2
8
DENS
9
Water
Saturated
Steam