Component 104: Coupled rectifying column

Specifications

Line connections
1	Inlet
2	Steam Outlet (rich in cooling-medium)
3	Fluid Outlet (poor in cooling-medium)
4	Added Heat in Expeller
5	Extracted Heat in Dephlegmator

General User Input Values Physics Used Displays Example

General

This component serves to reclaim the cooling agent from the solution rich in cooling agent coming from the absorber. The solution is fed from the side. Thereby, the fluid flows down via several intermediate bottoms. This area is called the extractor. Heat is fed bottom-up and brings the fluid to the boil. Here the fact is utilized that at first mainly the cooling agent will vaporize. It will rise up and sparkle through the intermediate bottoms, whereupon an equilibrium is reached in each bottom. This way, the gaseous cooling agent accumulates to the top and the solvent accumulates downward. The area above the injection is called the dephlegmator.

The extractor temperature can be fixed in the specification value T3, but it can also be calculated using a kernel expression ET3.
Flag FT3 has to be used to set whether T3 or ET3 is to be used.

User Input Values

XI2	Target refrigerant content in vapour outlet
EFF	Rectifier efficiency
FT3	Method for specification of generator outlet temperature Like in Parent Profile (Sub Profile option only) Expression =0: By specification value T3 =1: by Kernel Expression ET3
T3	Generator outlet temperature
ET3	By Kernel expression ET3 function evalexpr:REAL; // result must in °C begin evalexpr:=95.0; end;

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

Results

HDPH	(hypothetical) Dephlegmator pole (actual value)
HDPHMIN	Dephlegmator pole (theoretical minimum)
HGEN	Generator pole
DHDPH	Specific dephlegmation heat (actual value)
DHDPHMIN	Specific dephlegmation heat (theoretical minimum)
DHGEN	Specific generator heat
T3MIN	Theoretical minimum for generator temperature

Physics Used

Equations

All cases

The share of refrigerant of the liquid discharged on boiling conditions at given temperature T3:
XI3 = f(P3, T3)

Splitting ratios:
M2M1=(XI1-XI3)/(XI2-XI3)
M3M1=1 - M2M1

M3 - M3M1 * M1 = 0                                          (1)
M2 - M2M1 * M1 = 0                                          (2)
M5 = 1 (dummy value)                                           (3)

P1 - P2  = 0                                                         (4)
P1 - P3 = 0                                                         (5)
P5 = 0.01 (Dummy value)                                        (6)

for FBIN = NH3/H2O:

Gas emerging mixture is under saturated steam conditions

H2 = f(P2) (7)

for FBIN = H2O/LiBr:

Outlet temperature is equal to the desorbers temperature:
H2 = f(P2, T3) (7)

H3 = f(P3, T3)

for FBIN = NH3/H2O:

Calculation of the specific dephlegmator heat:

Case 1: Entry is still sub cooled

   HA = H'(P1,XI1)           boiling enthalpy
   HB = H_aux(P1,XI1)    auxiliary lines enthalpy in the h,xi-Diagram
   XIA = XI1                    Refrigerant fraction at the inlet
   XIB = XI"(P1,XIA)         XI the vapour phase

Case 2: Entry is wet steam (2-phase mixture)

   T1 = f(P1,H1)               temperature wet steam isotherm
   XIA = XI'(P1,T1)           XI of the liquid=
                                       starting point wet steam isotherm
   XIB = XI"(P1,T1)           XI the vapour phase=
                                       endpoint wet steam isotherm
   HA = H'(P1,XIA)           boiling enthalpy
   HB = H_aux(P1,XIA)     auxiliary lines enthalpy in the h,xi-Diagram

HDPHMIN = HA+(HB-HA)/(XIB-XIA)*(XI2-XIA)
DHDPHMIN=HDPHMIN-H2
DHDPH=DHDPHMIN/EFF

for FBIN = H2O/LiBr:
DHDPH = 0

H5 = DH_DPH * M2 (9)

-M1*H1+M2*H2+M3*H3-M4*H4+M5*H5=0 (10)

Component Displays

Display Option 1

Example

Click here >> Component 104 Demo << to load an example.

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