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Rigorous definition: Basic Specification Forms Components. Electrolytes Reliable design of new components. Kinetic CSTR

DIP_simu_04.ppt. Rigorous definition: Basic Specification Forms Components. Electrolytes Reliable design of new components. Kinetic CSTR reactors. 300 kg/h 30ºC, 1bar 10% W NA2CO3 . 10 stages. 200 m 3 /h 70ºC, 1 bar AIR + 2% MOL SH2. Components: Electrolytes.

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Rigorous definition: Basic Specification Forms Components. Electrolytes Reliable design of new components. Kinetic CSTR

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  1. DIP_simu_04.ppt • Rigorous definition: Basic Specification Forms • Components. • Electrolytes • Reliable design of new components. • Kinetic CSTR reactors.

  2. 300 kg/h30ºC, 1bar10%W NA2CO3 10 stages 200 m3/h70ºC, 1 barAIR + 2%MOL SH2 Components: Electrolytes EXAMPLE: Absorption of a stream, mixture of air and SH2, in an aqueous Na2CO3 solution. Check if the concentration of SH2 in the exit stream goes bellow 50 ppm. • Template: General with metric units. • Process flow diagram • Setup: • Title: Absorption of SH2 • Specify ‘molar flows’ and ‘mole fractions’ in the stream table.

  3. EXAMPLE: • Components: • DefinE: N2, O2, SH2, AGUA, NA2CO3 (AIR can not be defined as such because N2 and O2 have different Henry constants) • [Elec Wizard] • Include salt formation: OFF • Include water dissociation: ON • True component approach • Review Henry components: N2, O2, SH2, CO2.

  4. [Review generated Henry-comps list]: check the content of the GLOBAL group creado in /Componentes/Henry comps • Check: • /Properties/Specifications • Properties/ Parameters/ Binary interaction/ HENRY-1 , NRTL-1, VLCLK-1 • Properties/ Parameters/ Electrolyte Pair/ GMELCC-1, GMELCD-1, GMELCE-1, GMELCN-1

  5. Stream 1: • 200 m3/h, 70ºC, 1 bar, • AIRE + 2%MOL SH2 • Air: O2=0.98*0.21=0.206, • N2=0.98*0.79=0.774 • Stream 3: • 300 kg/h, 30ºC, 1bar, • 10%W NA2CO3 • D-110: • Configuration: 10 stages • Run • Results Available with errors •  DIP_04a.apw

  6. Errors are caused by a wrong choice of the convergence algotithm (default). • Ask for help for absorbers • EXAMPLE: DIP_04b.apw • /D-110/ Setup: Configuration: Convergence=Custom (in order to allow change the algorithm). • /D-110/ Convergence: Basic: Algorithm=Sum-Rates • Run •  DIP_04b.apw

  7. Try the alternative suggested solution: • /D-110/ Setup: Configuration: Convergence: Standard • /D-110/ Convergence: Advanced: Absorber=Yes /Run /Reinitialize [OK] [Aceptar] /Run /Start )  DIP_04c.apw

  8. Initial estimates: • /D-110/Estimates: Temperature Run  DIP_04d.apw

  9. /Blocks/D-110/Profiles: Compositions 10 ppm de SH2

  10. Benzene chlorination Design a plant to produce 10.000 Tm/year of monochlorobenzene (MCB). Maximum allowed production of polychlorinated products is 1.000 t/yr. • Literature: Ullmann and Kirk-Othmer encyclopaedias. • The reaction takes place in a stirred tank with liquid benzene and Cl2 gas. Low temperatures are used (20 - 80ºC).

  11. BEN 1 (82) MCB 2 (4.16) 3 (3.89) ODCB PDCB 4 (1.0) 6 (0.32) 5 (0.275) 123TCB 124TCB

  12. New component definition • A non-databank component is defined (123TCB is assumed to be a non-databank component) by the conventional procedure (not the Wizard). The reliability of the estimated values will be verified later. • Available data of 123TCB: MW = 181.45, Tb = 218.5 • Define all components: HCL, CL2, BEN, MCB, PDCB, ODCB, 124TCB y 123 TCB. • /Setup /Specifications: Run Type = Property Estimation • /Properties /Estimation /Input /Setup: Estimate all missing parameters. • /Properties /Molecular Structure: 123TCB .................. Define. • /Properties /Parameters /Pure Component: New , Scalar: MW = 181.45, Tb = 218.5 • Run DIP_MCB_a.apw /Properties /Molecular Structure: General /Properties/Parameters/Pure components/PURE-1: Input

  13. /Properties /Parameters /Pure component /PCES-1 /Properties /Estimation /Results: 123TCB Results may be displayed in /Properties /Estimation /Results, or in /Properties /Parameters /Pure components • NOTE: After estimation parameters are saved in the databank of the project file. The estimation form may be then disabled. The ‘Reinitialize’ command will no delete these values saved in the databank.

  14. Verification • Can we trust these estimates? The suitability of the methods used by Aspen Plus must be verified. Estimation methods are used for a databank component with similar molecular structure: 124TCB. • Two parameters are used to show the procedure: • Critical temperature (TC). • Standard enthalpy of formation for ideal gas (DHFORM). • Estimate TC y DHFORM by all available methods for 124TCB. • Compare with values in Aspen databank. •  DIP_MCB_b.apw /Properties /Estimation /Input: Pure Component: TC /Properties /Estimation /Input: Pure Component: DHFORM /Properties /Estimation /Input: Setup /Properties /Estimation /Compare: Setup

  15. Many errors are reported: • TC may not be estimated by MANI method becuse of missing parameters: Remove. • Molecular structure is required: Supply. • Run DIP_MCB_c.apw /Properties /Estimation /Results: Pure Component: 124TCB /Properties /Estimation /Compare Results: Pure Comp: 124TCB • While TC is correctly predicted by any method, DHFORM is always wrong, especially when the default method is used. • To continue the simulation disable the estimate input form and change the Run Type to Flowsheet mode.

  16. BEN 1 (82) MCB 2 (4.16) 3 (3.89) ODCB PDCB 4 (1.0) 6 (0.32) 5 (0.275) 123TCB 124TCB Reactor design • Choice of the reactor: • Considering reactions (mixed in series for MCB and in parallel for CL2) the choice of reactor may be elucidated: • A gas-liquid stirred tank reactor will be used for the reaction. Therefore several CSTR in series will be used, where BEN will flow in series, while CL2 will be fed in parallel to all reactors. • A low proportion of CL2 will also lead to higher selectivity. Furthermore, CL2 should react completely to avoid its mixture with hydrogen chloride at the outlet gas stream.

  17. /Properties /Estimation /Input: Setup: Do not estimate any parameters • /Setup/Specifications: Global: Runtype=Flowsheet • /Properties /Specifications: Global: Base Method=NRTL • /Properties /Specifications: Global: Henry components: <New> HC-1 [OK] • /Components /Henry components /HC-1: HCL, CL2 • /Properties /Parameters /Binary Interaction /NRTL-1: Input: Estimate all missing parameters by UNIFAC • Process flow diagram: • Stream 1: 20ºC, 1 bar, 100 kmol/h BEN • Stream 2: 20ºC, 1 bar, 200 kmol/h CL2 (use now CL2 in excess, to avoid errors, since kinetics are CL2 independent. A more realistic flow will be entered later). • CSTR: 0 bar, 20ºC (lower temperatures increase selectivity: Ea1<Ea2), Vapour-Liquid, Residence Time, 5 hours. • Reactions: define in /Reactions/Reactions: [New] (R-1, POWERLAW).

  18. BEN 1 (82) MCB 2 (4.16) 3 (3.89) ODCB PDCB 4 (1.0) 6 (0.32) 5 (0.275) 123TCB 124TCB Kinetics • All reactions show first-order kinetics with respect to the aromatic reactive and zero-order with respect to CL2 (liquid phase is saturated of CL2). • Parameters are available in literature for the two main reactions (1 and 2). For the other polychlorination reactions the same Ea that in reaction 2 will be assumed. The exponential factor will be calculated from K conversion factors reported in Kirk-Othmer encyclopaedia.

  19. /Blocks/R-130 /Setup: Specifications REACTIONS: /Reactions/Reactions: [New], R-1, Powerlaw /Reactions/Reactions/R-1: Kinetic Fill out the form for the 6 reactions • DIP_MCB_d.apw

  20. RUN /Data /Results Summary /Streams R-310: Results

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