Eurotherm 6100, User Manual

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100/180MM DISTRIBUTED GRAPHIC RECORDER: USER GUIDE
Page 112 HA029324
Issue 11 Oct 14
4.3.11 FUNCTION (Cont.)
SATURATED STEAM HEAT FLOW
Note: The overall accuracy of a fl ow measurement installation depends on a number of fac-
tors outside the control of the recorder manufacturer. For this reason, the recorder manu-
facturer takes no responsibility for the accuracy of the results obtained using the mass fl ow
equations implemented in the maths pack.
The equations solved is:
Function
Flow
Use
Pressure
Dryness
Units
Maths Number
Value
Units
Apply Discard
%
Saturated Steam Heat Flow
Channel 1
10
Units
2) Math 2
987.6543
Pressure
Channel 2
Figure 4.3.11j Typical Saturated Steam Heat Flow confi guration page
PARAMETERS
Flow
Select ‘Constant’ or the number of the channel supplying the measured fl ow rate. If ‘Constant’
selected, a further ‘box’ allows the value for the constant to be entered.
Use Allows the user to select Temperature (˚C) or Pressure (MPa) for the calculation.
Temperature Appears only if Use = Temperature. Select ‘Constant’ or the number of the channel supplying the steam
temperature. If ‘Constant’ is selected, a further ‘box’ allows a value for the constant to be entered.
Pressure (note 3) Appears only if Use = Pressure. Select ‘Constant’ or the number of the channel supplying the steam
pressure. If ‘Constant’ is selected, a further ‘box’ allows a value for the constant to be entered.
Dryness Enter a value between 0 and 100 to represent the dryness of the steam. 0 = no vapour; 100 = no liquid.
Notes:
1 The units of kg/sec and m
3
/sec are used above for simplicity. In fact any time unit can be used.
For example if the measured fl ow is in m
3
/hour, then the Mass fl ow will be in kg/hour.
2. ASME Steam tables 1999, from IAPWF IF97.
3. See ‘
Saturated Steam Mass Flow ’ above for details of pressure unit conversion
where, QE
t
= Heat energy fl ow (in kJ/sec), at time ‘t’ (Note 1)
Flow
t
= Measured fl ow in m 3 /sec (Note 1)
V
LT
= Volume of liquid per kg of steam (m 3 /kg) at temperature T ˚C
ΔV
T
= V
VT
- V
LT
, where V
VT
is the volume of vapour per kg of steam at temperature T ˚C
d = Dryness factor between 0 (no vapour) and 100 (no liquid)
h
LT
= Enthalpy of the liquid in kJ/kg at temperature T ˚C
Δh
T
= h
VT
- h
LT
, where h
VT
is the enthalpy of vapour in kJ/kg vapour at temperature T ˚C
V
LT
and ΔV
T
; h
LT
and Δh
T
are available from published tables (note 2), but the recorder user needs only to enter ‘val-
ues’ for measured fl ow and either the temperature or the pressure of the steam. These ‘values’ can be constants,
input channels or maths channels. Figure 4.3.11j and accompanying parameter descriptions give full details.
QE
t

Flow
t
V
LT
 
V
T
d
100
 








h
LT
 
h
T
d
100
 
 