modelKettleReboilerEq

equilibrium model

Extends from ThermalSeparation.Icons.Color.Reboiler.

Information

Kettle reboiler - shell side

The reboiler is modelled as an evaporator with one liquid input and one liquid and vapour output respectively. The model consideres only the shell side of a kettle reboiler. On the inside the reboiler contains a weir which determines the maximum liquid level. Once the liquid level rises above the weir height a liquid stream starts to exit the reboiler. To model this process the francis-weir-formula is used.

Mass and ernergy balances contain both liquid and vapour phases together. This means both phases are at thermodynamic equilibrum at any time.

For now no startup processes from empty and cold states are considered. This means at t=0s the reboiler is already partially filled with liquid that has a temperature near the boiling point.

So far no heat transfer resistance is considered for the heating. The amount of heat introduced into the reboiler is supplied by a real Input and directly accounted for in the energy balance. Also no pressure loss is calculated at the moment.

The model can handle inert substances in the liquid phase. In case the liquid phase contains an inert the user has to specify which substances of the component vector are inert. If any chemical reactions occur they can also be taken into account. Reaction model and correlation for vapour-liquid equilibrium can both be selected via a dropdown menu.

For initialisation the user can opt for either standalone operation or usage in larger systems because in standalone operation it is not possible to initialise the pressure since it is already given by the vapour sink.

Parameters

TypeNameDefaultDescription
Booleaninit_standalonetruechanges number of initial values if used in standalone operation
Modelica.Units.SI.HeatFlowRateQ_loss0heat loss to ambience
Integer[nS,2]mapping{{1, 1}, {2, 2}}parameter to map the different medium vectors one to another
IntegernS2number of omspecies which are equal in vapour and liquid phase
IntegernLnSL - nSnumber of additional substances which are only in liquid phase
IntegernVnSV - nSnumber of additional substances which are only in the vapour phase
IntegernSLMediumLiquid.nSubstance
IntegernSVMediumVapour.nSubstance
Boolean[nSL]inert_Liquidfill(false, nSL)true for inert components in liquid phase
RealRModelica.Constants.R
Modelica.Units.SI.AreaA_HTheat exchange area
Modelica.Units.SI.AreaA0.5area of reboiler
Modelica.Units.SI.HeightH1.3height of reboiler
Modelica.Units.SI.Lengthh_w0.13
Modelica.Units.SI.Lengthh_lw0.35
Initialization
ThermalSeparation.Components.Reboiler.InitOptionEqinit_optionEnumerations.InitializationOption.init_xinitialization options
Realeps_liq_initinitial value for eps_liq
Modelica.Units.SI.TemperatureT_initinitial value fr Temperature
Modelica.Units.SI.Pressurep_initinitial value for pressure
Realfixed_mol_initmolarity of solvent
Modelica.Units.SI.MoleFraction[nS]x_total_startmole fraction of component in vapour and liquid
Advanced
Modelica.Units.SI.TemperatureT_refsystemTS.T_refreference temperature
Initialization › Init. from constant value
Booleaninit_const_vdotfalseinitialise from constant vapour volume flow rate
Modelica.Units.SI.VolumeFlowRatevdot_v_const0.08volume flow rate
Realomega_k0.05large value if change between constant and variable shall be steep
Realomega_time50inflexion point of tanh function

Connectors

TypeNameDefaultDescription
ThermalSeparation.Interfaces.GasPortOutgasPortOut
ThermalSeparation.Interfaces.LiquidPortInliquidPortIn
ThermalSeparation.Interfaces.LiquidPortOutliquidPortOut
Modelica.Thermal.HeatTransfer.Interfaces.HeatPort_aheatPort

Components

TypeNameDefaultDescription
ThermalSeparation.SystemTSsystemTS
Modelica.Units.SI.HeatFlowRateQ_inheat flow to evaporate liquid
Modelica.Units.SI.TemperatureT_l_in
Modelica.Units.SI.MoleFraction[nSL]x_l_in
Modelica.Units.SI.Concentration[nSL]c_l_in
Modelica.Units.SI.VolumeFlowRatevdot_l_in
Modelica.Units.SI.Pressurep_sys
Modelica.Units.SI.MolarFlowRateF_in_l
Real[nS]K
Modelica.Units.SI.MolarFlowRateF_out_l
Modelica.Units.SI.MolarFlowRateF_out_v
Modelica.Units.SI.AmountOfSubstanceHU_l
Modelica.Units.SI.AmountOfSubstanceHU_v
MediumVapour.BasePropertiesmediumVapour
MediumLiquid.BasePropertiesmediumLiquid
MediumLiquid.BasePropertiesmediumLiquidIn
ThermoEquilibriumthermoEquilibrium
Modelica.Units.SI.MolarFlowRate[nSL]Ndot_l_transfer
Reactionreaction
Col_Geometry.BasicGeometrygeometry
InnerHTinnerHT
Modelica.Units.SI.TemperatureT
Modelica.Units.SI.MoleFraction[nSL]x_l
Modelica.Units.SI.MoleFraction[nSV]x_v
ThermalSeparation.Units.MolarEnthalpyh_l_in
ThermalSeparation.Units.MolarEnthalpyh_vmediumVapour.h
ThermalSeparation.Units.MolarEnthalpyh_l
ThermalSeparation.Units.MolarEnthalpyh_feed0
ThermalSeparation.Units.MolarEnthalpyu_lmediumLiquid.u
ThermalSeparation.Units.MolarEnthalpyu_vmediumVapour.u
Modelica.Units.SI.MolarMassMM_lmediumLiquid.MM
Modelica.Units.SI.MolarMassMM_vmediumVapour.MM
Modelica.Units.SI.MolarMassMM_l_inmediumLiquidIn.MM
Modelica.Units.SI.Densityrho_lmediumLiquid.d
Modelica.Units.SI.Densityrho_vmediumVapour.d
Modelica.Units.SI.Densityrho_l_inmediumLiquidIn.d
Modelica.Units.SI.Pressure[nSL]p_sat
Modelica.Units.SI.VolumeV_vap
Modelica.Units.SI.VolumeV_liq
Modelica.Units.SI.VolumeV_abs
Modelica.Units.SI.Concentration[nSL]c_l
Realdummy_c_lc_l[2]
Modelica.Units.SI.Concentration[nSV]c_v
Modelica.Units.SI.VolumeFlowRatevdot_l
Modelica.Units.SI.VolumeFlowRatevdot_v
Modelica.Units.SI.SpecificHeatCapacitycp_col500
Modelica.Units.SI.Massm_col100
Modelica.Units.SI.Heighth_liq
Realeps_liq(liquid volume) / (absolute volume)
Realeps_vap(vapour volume) / (absolute volume)
Modelica.Units.SI.Pressurep_bubbubble point pressure
RealcheckMoleBal
Modelica.Units.SI.MassFlowRatemdot_lvdot_l*rho_l
Modelica.Units.SI.MassFlowRatemdot_vvdot_v*rho_v
Modelica.Units.SI.MassFlowRatemdot_l_invdot_l_in*rho_l_in
Modelica.Units.SI.MassFlowRatemdot_checkmdot_l_in - mdot_l - mdot_v
Realomega0.5*tanh(omega_k*(time - omega_time)) + 0.5

Contents

NameDescription
MediumVapour
MediumLiquid
ThermoEquilibrium
Reaction
Col_Geometry
InnerHT