Component 34: Expander

In This Topic

Component 34: Expander

Specifications

Line connections
1	Inlet
2	Saturated steam outlet
3	Extraction of condensate
4	Injection of cooling water

General User Input Values Physics Used Displays Example

General

The inlet condensate introduced into the expander, is eased on a lower pressure level.

You can choose between two working conditions of the expander:

1. The saturated steam arising during the expansion is condensed completely with the help of the cooling water shower and is also extracted sub cooled.

2. The saturated steam arising during the expansion is condensed and the extracted condensate is mixed with cooling water and sub cooled.

This component can also be operated with salt water as the inlet fluid. The evaporation thereby changes the salt content.

The component can be used for modeling simple desalination processes. However, the component 92 (MSF stage) is needed for a more realistic and stable modeling of complex desalination plants.

User Input Values

DPN	Pressure drop (nominal) DPN=P1N-P2N
DT3S3	Sub Cooling temperature difference DT3S3=T3S-T3
FMODE	Flag for calculation mode Like in Parent Profile (Sub Profile option only) Expression =0: GLOBAL =1: Local off-design =-1: Local design
FP	Type of pressure calculation Like in Parent Profile (Sub Profile option only) Expression =1: P2 results from P1 and pressure drop DPN =2: P2 or P3 are specified from outside (e.g. with the components 1, 12, 36: boundary value, controllers and value transmitter respectively)
FSPEC	Water injection Like in Parent Profile (Sub Profile option only) Expression =1: complete condensation of steam and sub cooling of the condensate by M4 to T3=T3S-DT3S3 =2: Steam separation M2=X(P2=P3,H1)*M1, then cooling of the condensate by M4 to T3=T3S-DT3S3
M1N	Mass flow (nominal)

The parameters marked in blue are reference quantities for the off-design mode. The actual off-design values refer to these quantities in the equations used.

Generally, all inputs that are visible are required. But, often default values are provided.

For more information on colour of the input fields and their descriptions see Edit Component\Specification values

For more information on design vs. off-design and nominal values see General\Accept Nominal values

Physics Used

Equations

All cases

if GLOBAL = design, then {

F1 = 1 }

else {

F1 = (M1/M1N)**2 }

DP = DN * F1

P2 = P1-DP

P2 from outside (FP = 2)

P3 = P2

if FSPEC = 1 (no steam outlet), then {

H2 =H’’(P2)

H3 = f (P3,T3S-DT3S3)

M2 = 0

M4 = M1*(H1 - H3) / (H3 - H4)

M1 + M4 - M2 - M3 = 0

}

if FSPEC = 2 (steam outlet), then {

X = f(P2,H1)

H3 = f(P3,T3S-DT3S3)

if X = 1, then {

M2 = M1

M4 = 0

M1 + M4 - M2 - M3=0

H2 = H1

}

if X = 0, then {

M2 = 0

M4 = M1* (H1 - H3) / (H3 - H4)

M1 + M4 - M2 - M3 = 0

H2 = H’’(P2)

}

if 0<X< 1, then {

M2 = M1 * X

M33= M1 * (1 - x)

H33= f(P3,T3S)

M4 = M33* (H33 - H3) / (H3 - H4)

M1 + M4- M2- M3 = 0

H2 = H’’(P2)

}

Component Displays

Display Option 1

Example

Click here >> Component 34 Demo << to load an example.