EBSILON®Professional Online Documentation
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Line connections |
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1 |
Gas or raw gas inlet |
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2 |
Gas or raw gas outlet |
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3 |
Steam / Water feed |
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4 |
Heat of reaction needed |
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General User Input Values Characteristic Lines Physics Used Displays Example
Component 95 can model a reformer or a shift-reactor.
The basis of the model is a complete equilibrium calculation based on maximization of the irreversible percentage of entropy. The component takes into account the components CO, CO2, H2, H2O, O2, CH4, C2H2, C2H6, methanol and solid carbon. All other components of the C, H, O system are set to zero.
This description is identical to the solution of the element balance for H, C, O and the solution of the other equilibrium references via the independent reaction equations, e.g.
CO + H2O = CO2 + H2
C + CO2 = 2 CO
C + H2O = CO + H2
CO +3 H2 = CH4 +H2O
C + 2 H2 = CH4
CO + H2 = C + H2O
C2H2 +2H2O = 2CO + 3 H2
C2H6 +2H2O = 2CO + 5 H2
The solution of these equations also fulfils all the possible equilibrium references of the C, H, O system.
The specification values enable the specification of different conditions for
which covers most of the applicable configurations.
It is possible to take out individual (or all) components from the thermodynamic equilibrium, in order to be able to take into account the kinetic effects in this way.
The components of the shift-reaction (H2, CO, H2O and H2O) can either be calculated together from the equilibrium, or else no equilibrium is calculated at all. In this case, the H2-, CO-, H2O- or CO2-concentration must be specified alternately at the outlet. The other components then result respectively from the element balances for C, H and O.
When the components of the shift-reaction are calculated in equilibrium, one can then define individually for methane, acetylene, benzene, methanol and solid carbon, whether this substance should also be calculated in the equilibrium, be passed on unchanged or should achieve a specific outlet concentration.
In order to record all the deviations from the thermodynamic equilibrium in one go, an approach-temperature can be specified. This is defined as the difference between the temperature to be used for calculating the equilibrium and the actual temperature.
Flexible Treatment of Errors
In this component, a flag FERR has been implemented that allows the user to select how the component is to react if a desired specification for the material concentration cannot be adhered to:
The substance concentration is set to the value that is just possible (this can be the minimum or maximum value, depending on the case).
When specifying values for the substances of the water gas reaction (CO, CO2, H2 and H2O), however, the case may arise that there is no solution, for example if the inlet flows are more C than O (material balance violated). In this case, the material balance is closed by elementary C or free O2.
A message on this is output that lies one level below the message level set in FERR, i.e. by default a warning.
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FSPEC |
Flag for calculating the components of the shift-reaction (H2, CO, H2O, CO2) Like in Parent Profile (Sub Profile option only) Expression =0: Calculation of the components from the thermodynamic equilibrium =1: Specification of the H2-mass fraction in XOUT, calculation of the remaining elements from the element balance =2: Specification of the CO-mass fraction in XOUT, calculation of the remaining elements from the element balance =3: Specification of the H2O-mass fraction in XOUT, calculation of the remaining elements from the element balance =4: Specification of the CO2-mass fraction in XOUT, calculation of the remaining elements from the element balance |
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XOUT |
Outlet concentration of the components according to FSPEC |
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FEQ |
Flag for equilibrium temperature (= Temperature at which the C is calculated): Like in Parent Profile (Sub Profile option only) Expression =1: T- equilibrium = T1 + TAPP =2: T- equilibrium = T2 + TAPP =3: T- equilibrium = T3 + TAPP =4: T- equilibrium = TEQ |
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TAPP |
Approach Temperature |
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FC |
Flag for handling the elementary carbon: Like in Parent Profile (Sub Profile option only) Expression =0: calculated from the thermodynamic equilibrium =1: is passed on unchanged =2: outlet concentration specified by XC |
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XC |
Outlet concentration for elementary carbon (for FC = 2) |
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FCH4 |
Flag for handling Methane: Like in Parent Profile (Sub Profile option only) Expression =0: calculated from the thermodynamic equilibrium =1: is passed on unchanged =2: outlet concentration specified by XCH4 |
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XCH4 |
Outlet concentration for Methane (for FCH4 = 2) |
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FETH |
Flag for handling Ethane: Like in Parent Profile (Sub Profile option only) Expression =0: calculated from the thermodynamic equilibrium =1: is passed on unchanged =2: outlet concentration specified by XETH |
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XETH |
Outlet concentration for Ethane (for FETH = 2) |
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FMETHL |
Flag for handling Methanol: Like in Parent Profile (Sub Profile option only) Expression =0: calculated from the thermodynamic equilibrium =1: is passed on unchanged =2: outlet concentration specified by XMETHL |
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XMETHL |
Outlet concentration for Methanol (for FMETHL = 2) |
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FACET |
Flag for handling Acetylene Like in Parent Profile (Sub Profile option only) Expression =0: calculated from the thermodynamic equilibrium =1: is passed on unchanged =2: outlet concentration specified by XACET |
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XACET |
Outlet concentration for Acetylene (for FACET = 2) |
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FSPECM |
Flag for specifying the mass flows Like in Parent Profile (Sub Profile option only) Expression =1: Mass flow M1 and M3 given =2: Mass flow M1 or M3 given, calculation of the other mass flow via RH2OC |
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FSPECT |
Flag for specifying the outlet temperature Like in Parent Profile (Sub Profile option only) Expression =1: Temperature T2 given from outside =2: Temperature given via T2SET |
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FGIBBS |
Gibbs potential (not used) |
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RH2OC |
Molar ratio H2O to C |
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T2SET |
Outlet temperature T2 |
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TEQ |
Temperature for calculation of equilibrium |
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FERR |
Flag for notification if requested outlet concentration is not possible Like in Parent Profile (Sub Profile option only) Expression =0: No notification |
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
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All cases (no separate off-design mode) |
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Pressure calculation P1 = P2 P3 greater than P1,P2
Mass flow calculation M2 = M1+M3 Element composition Calculation of the element composition (EL(I)) of the element I from the weight fractions (GAT(J)), of the components via the element-component matrix A(I,J) (element I in component J), M molecular weight EL(I) = SUM via J((GAT(J)*A(I,J)*M(I)/M(J))
PARAMETER -------------------------------------------- IF FSPECM= 1 THEN -------------------------------------------- M1 and M3 defined via other components -------------------------------------------- ELSEIF FSPECM = 2 THEN -------------------------------------------- M3ZUM1 = RH2OC*MH2O/MC*EL(C) M3 = M3ZUM1*M1 FSPECM END -------------------------------------------- IF FSPECT = 1 THEN T2 via H2 from outside ELSEIF FSPECT = 2 T2 = T2SET H2 = H2(P2,T2) FSPECT END -------------------------------------------- IF FSPEC = 1 Tequilibrium = T1 IF FSPEC = 2 Tequilibrium = T2 IF FSPEC = 3 Tequilibrium = T3 IF FSPEC = 4 Tequilibrium = TEQ -------------------------------------------- Calculation of the composition according to the method of maximization of the (irreversible) entropy at Pequilibrium = P1 and Tequilibrium, components are described above -------------------------------------------- Balance of energy (Calorific value calculation Line 2) Q4 = M2*(H2+HU2)-M1*(H1+HU1)-M3*H3 |
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Display Option 1 |
Click here >> Component 95 Demo << to load an example.
