Precipitator3 Data Sections

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Precipitation3 Model Theory - Growth Model Theory - PSD Model Options Data Sections Dynamic Mode Batch Operations (Probal)

Latest SysCAD Version: 26 October 2021 - SysCAD 9.3 Build 139.29722

Related Links: Alumina 3 Bayer Species Model


Precipitator3 Tab

Unit Type: Precipitator3 - The first tab page in the access window will have this name.

Tag (Long/Short) Input / Calc Description/Calculated Variables / Options
Tag Display This name tag may be modified with the change tag option.
Condition Display OK if no errors/warnings, otherwise lists errors/warnings.
ConditionCount Display The current number of errors/warnings. If condition is OK, returns 0.
GeneralDescription / GenDesc Display This is an automatically generated description for the unit. If the user has entered text in the 'EqpDesc' field on the Info tab (see below), this will be displayed here.
If this field is blank, then SysCAD will display the unit class ID.

Requirements

On Tick Box This can be used to take a precipitator off line. When a precipitator is not ON, the input stream will act as though it has bypassed the precipitator, thus no change will occur in this unit. This option is useful for feasibility studies of flowsheet configuration.
TankBypass Tick box Feed bypasses entirely to Product, tank contents continue to react. Dynamic only
Bypass Tick box Allows bypassing of a fraction of feed directly to outlet. Bypassing for more information.
In Dynamic mode, this represents short-circuiting of feed to product, so will only occur while the tank is overflowing, else all feed is added to tank contents.
BypassFraction Input How much of the feed to bypass, visible if Bypass is on.
TankVol Input The precipitation tank volume, used to calculate the residence time.
LevelControl Tick Box Enable tank level control. Dynamic only with Underflow connection.
Level.Spt Input Target level for level control. Dynamic only with LevelControl enabled.
Level.QvMin Tick Box Minimum underflow flowrate for level control. Dynamic only with LevelControl enabled. Default 0.
Level.QvMax Tick Box Maximum underflow flowrate for level control. Dynamic only with LevelControl enabled. Default '*' (unrestricted).
BatchMode Tick Box Adds the Batch & Cycle tabs. The precipitator model will operate in a pseudo-dynamic batch mode, simulating a tank which is filled with separate feed and seed streams, allowed to precipitate, then drained. See Batch Mode for more information.
Cooling None No cooling required.
Embedded Uses embedded cooler for cooling. User do not need to add the cooler unit. A Cooler Tab becomes visible and can be configured. See also Cooler Options for more information.
External Uses external cooler for cooling. User will need to add the cooler unit separately. A Cooler Tab tab becomes visible and can be configured. See also Cooler Options for more information.
Reactions Off No extra reactions
On This allows the user to add extra reactions to the model. Note that THA precipitation and Soda co-precipitation are built-in reactions, user do not need to specify these. When this option is on, RB becomes visible and may be configured. See Reactions for more information.
Classification Tick Box Adds the Classif tab. Allows Solid and liquid separation using an internal General Separator model. See Classification for more information.
ThermalOverride None Don't override.
TempDrop Overall heat loss based on Temperature Drop. Note that calculated HOR and cooling effects are ignored as this temperature drop is applied as an overall override.
ProductT Specify the product temperature.
TempDropReqd / TDropReqd Input The overall temperature drop required, visible with the TempDrop ThermalOverride Method.
TemperatureReqd / T_Reqd Input The overall exit temperature required, visible with the ProductT ThermalOverride Method.
ThermalLossMethod
(Only visible if the ThermalOverride
is set to NONE.)
None No additional heat loss to the environment or thermal balance overrides.
TempDrop Additional heat loss based on Temperature Drop. In this case the temperature drop is applied on top of HOR and cooling effects.
FixedLoss Additional heat loss is expressed as a fixed amount of energy.
Ambient Additional heat loss is expressed as Energy/degree of temperature difference to ambient.
WindAmbient More detailed ambient model accounting for wind speed. See Thermal Loss Method for equation and limits.
WindAmbient2 More detailed ambient model accounting for wind speed. See Thermal Loss Method for equation and limits.
TempDropReqd / TDropReqd Input The temperature drop required (for energy loss not necessarily the overall tank temperature drop), visible with the TempDrop Method.
ThermalLossReqd Input The amount of energy to be lost to the environment, visible with the FixedLoss method. (Positive for heat outflow)
ThermalLossAmbient Input The amount of energy per degree to be lost to the environment, visible with the Ambient method.
LocalWindSpeed Tickbox Visible with the WindAmbient ThermoLossMethod. Selecting this option allows user to use a local wind speed, this could be different than that specified in the Plant Model - Environment tab. If it is not selected, then the value specified in the Plant Model - Environment will be used.
WindSpeedUsed Result Displays the actual wind speed used.
WindLossRateK Input Rate, visible if WindAmbient option for thermal loss is selected.
TankSurfaceArea Input Tank external surface area including both top and side, visible if WindAmbient option for thermal loss is selected.
LocalAmbientT Check Box Allow individual tank specification of ambient temperature. If off, PlantModel.Environment.T is used.
AmbientT.Reqd Input Local ambient temperature for thermal loss and evaporation calculations using Ambient. Visible if LocalAmbientT is enabled.
 
Evaporation None No evaporation loss to the environment.
Fixed Fixed evaporation rate. Suggested values are in the range 0.25 to 1.0 t/h.
Ambient Fixed evaporation rate per degree of temperature. Suggested values are in the range of 0.005 to 0.025 t/h.K.
Evap.Rate Input The evaporation rate required, visible with the Fixed Method.
Evap.Per.degK Input The evaporation rate required per degree of temperature, visible with the Ambient method, or overall constant for detailed model.
ProdGasEntrainment Input The fraction of vapours which report to the Product stream rather than the Vent. This includes any vapours from the feed stream or gasses evolved from reactions. This excludes water from evaporation. Default 0%.
 
OperatingP - NOTE: this pressure is applied to the (combined) feed, before sub-models (if any).
Method AutoDetect If there are any liquids AND no vapours present in the feed, outlet streams will take the highest pressure of the feeds. Else (eg. some vapours present) outlet streams will take the lowest pressure of the feeds.
LowestFeed Outlet streams will take the lowest pressure of the feeds.
HighestFeed Outlet streams will take the highest pressure of the feeds.
Atmospheric Outlet streams will be at Atmospheric Pressure. The atmospheric pressure is calculated by SysCAD based on the user defined elevation (default elevation is at sea level = 101.325 kPa). The elevation can be changed on the Environment tab page of the Plant Model.
RequiredP Outlet streams will be at the user specified pressure.
IgnoreLowMassFlow / IgnoreLowQm Tick Box This option is only visible if the AutoDetect, LowestFeed or HighestFeed methods are chosen. When calculating the outlet pressure and temperature of the tank, SysCAD will ignore the low flow feed streams should this option be selected. The low flow limit is set in the field below.
LowMassFlowFrac / LowQmFrac Input This field is only visible if the IgnoreLowQm option is selected. This is the amount any stream contributes to the total flow. For example, if the total feed to the tank is 10 kg/s, and this field is set to 1%. Then any feed streams with less than 0.1 kg/s will be ignored in the pressure calculations.
PressureReqd / P_Reqd Input This field is only visible if the RequiredP method is chosen. This is user specified pressure.
Result Calc The actual pressure used for the sum of the feeds which will also be the outlet pressure (unless further model options change the pressure).

PresetData

(Dynamic Only)

UsePresetImg Tickbox Selecting this option will add the Preset + DSp Tabs, allowing user to define a pre-made mixture to be used to preset the contents of the precipitator.
Temperature / T Input User specified preset Temperature, used when the preset tank command is executed.
Level / T Input User specified preset level, used when the preset tank command is executed.

Options

ShowQFeed Tick box Switches on the QFeed tab pages to display the total feed stream properties into the Precipitator. This is useful if more than one Feed streams are connected to the precipitator. See Material Flow Section.
ShowQTank Tick box Visible if Bypass is on. Switches on the QTank tab pages to display the tank contents exit stream properties before adding the bypass to give the exit stream (QProd). See Material Flow Section.
ShowQEvap Tick box Visible if Evaporation method selected. Switches on the QEvap tab pages to display stream details of the evaporated water. See Material Flow Section.
ShowQVent Tick box Visible with Vent connection. Switches on the QVent tab pages to display the vent stream properties from the Precipitator. This may include water vapour from evaporation. See Material Flow Section.
ShowQProd Tick box Switches on the QProd tab pages to display the product stream properties from the Precipitator. This may include vent gasses if no Vent stream connected. See Material Flow Section.
ShowQTubeIn Tick box Visible if embedded cooling. Switches on the QTubeIn tab pages to display cooling tubes inlet stream properties. See Material Flow Section.
ShowQTubeOut Tick box Visible if embedded cooling. Switches on the QTubeOut tab pages to display cooling tubes outlet stream properties. See Material Flow Section.

Results Tank

ResidenceTime Calc The calculated residence time of the slurry in the unit.
TotalMass / Mt Calc The total mass of the slurry in the unit.
SolidMass / SMt Calc The mass of the solid in the unit.
Eff.ResidenceTime Calc Effective solids residence time from Classification. Note: when classification is used, solids have a longer residence time due to internal recycle.
Level Calc Tank level as fraction of volume. Dynamic Only
QmAcc Calc Nett inflow rate Dynamic Only
MtAcc Calc Nett inflow Dynamic Only
SuperSat Calc The Supersaturation = Product A/C divided by Equilibrium A/C = (A/C) / (ASat@ProdcutT / C@25).
Solids.Conc Calc The solids concentration in the unit referenced to 25°C.

Yield

(in grams Al2O3 per liter liquor @ 25C)

Yield Calc The calculated Yield = Gibbsite precipitated as equivalent Alumina per unit volume of feed liqour at 25°C. Note: in Dynamic, this is the difference in THA between feed and product streams, and may be negative or meaningless if tank is filling or in batch operation.
YieldRate Calc Rate of increase in THA solids (gpl/hr) Dynamic Only
THA.Precip Calc The mass of Trihydrate Alumina Al[OH]3 precipitated in the unit.
Al2O3.Precip Calc The mass of Trihydrate Alumina Al[OH]3 precipitated in the unit, expressed as Al2O3.
Solids.Precip Calc The mass of solids precipitated in the unit, includes THA, bound soda and bound organics.

Oxalate

(Only visible if the oxalate precipitation is on.)

Oxalate.Precip Calc The mass of oxalate precipitated in the unit.
Oxalate.Yield Calc The mass yield of oxalate in the tank (g Na2C2O4 / L liquor). Only shown in Steady State.
Oxalate.Solubility Calc The oxalate solubility at equilibrium (g Na2C2O4 / L).
Oxalate.SSN Calc The oxalate relative super saturation level (Ox / Ox* - 1).

Results

MassFlowIn / Qmi Calc The mass flowrate at the inlet conditions.
MassFlowOut / Qmo Calc The mass flowrate at the Product Stream. Note: If the classification option is on, this shows the classifier overflow (product) flowrate. The underflow flowrate is shown under the Results Underflow section.
MassFlowLoss / QmLoss Calc This shows the mass flow difference between inlet and outlet streams. If vapour is present (due to reactions or evaporation) and the vent stream is not connected, then the vapour will be discarded, the mass imbalance value will be shown here.
VolFlowIn / Qvi Calc The volumetric flowrate at the inlet conditions.
VolFlowOut / Qvo Calc The volumetric flowrate at the outlet conditions.
BypassQm Calc The mass flowrate of the bypass material.
BypassQv Calc The volumetric flowrate of the bypass material.
TemperatureIn / Ti Calc The inlet temperature.
TemperatureOut To Calc The outlet Temperature.
ACin Calc The A/C ratio at the inlet conditions.
ACout Calc The A/C ratio at the outlet conditions.
ACequil / ACSat Calc The Asat/C ratio at the outlet conditions.
BoundSodaFraction Calc (The bound soda and bound organics precipitation rate expressed as Na2O) / (THA precipitation rate expressed as Al2O3).
BoundSodaPrecip Calc The bound soda precipitation rate. If NaOH*(s) is present in the project, this will show the bound soda as NaOH, otherwise this will show bound soda expressed as Na2O.
  • The total bound soda/organic precipitated = BoundSodaPrecip + BoundOrganicsPrecip
BoundSodaPerTHA Calc (The bound soda precipitation rate expressed as "boundsodaspecies") / (THA precipitation rate expressed as Al[OH]3).
BoundOrganicsPrecip Calc The bound organic precipitation rate - expressed as the bound organic species, such as Na2C5O7*(s).
  • The total bound soda/organic precipitated = BoundSodaPrecip + BoundOrganicsPrecip

Results Underflow

Only visible with Classification option selected.

UF.MassFlow / UF.Qm Calc The mass flow of the underflow stream.
UF.SolidMassFlow / UF.SQm Calc The solid mass flow of the underflow stream.
UF.SolidFrac / UF.Sf Calc The solid mass fraction of the underflow stream.
UF.VolFlowOut / UF.Qv Calc The volumetric flow of the underflow stream.

Precip Tab

Tag (Long/Short) Input / Calc Description/Calculated Variables / Options
Precip.On Tickbox Enable precipitation chemistry functionality. Dynamic only
Precip.Method SSA Uses the specified seed surface area estimated from the input stream conditions. User can specify a SSA value by ticking the OverrideSSA option. NOTE: If there is a PSD in the feed, it will be removed from the outlet stream.
PSD Use the Full Particle Size Distribution (PSD). Refer to Alumina3 Precip - Full PSD for more information.

Hydrate Precipitation

GrowthMethod Fixed User specifies a fixed alumina precipitation rate (as a mass flow rate).
FixedRate The alumina precipitation rate is calculated from a fixed user specified growth rate.
White-Bateman The alumina precipitation rate is calculated using the White Bateman correlations [2]. See Growth Rate Theory for information.
Veesler-Boistelle The alumina precipitation rate is calculated using the Veesler Boistelle correlations [7]. See Growth Rate Theory for information.
SSA Yield The alumina precipitation rate is calculated taking into account factors of free caustic, total organic carbon, soda concentration and SSA. See Growth Rate Theory for information.
GrowthAsDeposition Input Removed in Build 139. Defines growth rate as radial/crystal growth (true) or diametric/particle growth (false).
UseCorrectedGrowthRate Input Added in Build 139 (may be visible if upgrading from 138). Removes GrowthAsDeposition option - radial and diametric growth are both calculated and applied as required by different growth and agglomeration methods. Recommend this box be checked and model retuned if necessary.
GrowthRateCorr Input Growth rate correction factor, applied to all methods except Fixed.
VolumeCorrection Tickbox Reduces precipitation rate for alumina and bound soda to account for excess volume in Dynamic calculation step. May be useful for large time steps. Default off. Dynamic only
OverrideSSA Tickbox visible with Precip.Method set to SSA. Allows user to specify a SSA value for the precipitation tank. Any feed stream value will be ignored.
AdjustProdSSA Tickbox Adjust product stream SSA to account for particle growth (using spherical model).
  • When using the SSA method, the adjusted product SSA = FeedSSA * [(FeedSolidMass/ProductSolidMass)^(1/3)]
  • If unchecked, the product SSA will be the same as the feed SSA (when Precip.Method is StreamSSA) or the user specified SSA (when Precip.Method is UserSSA).
  • Not visible when Precip.Method is FullPSD. In a full PSD model, the SSA may increase or decrease depending on the initial size distribution and the effects of nucleation and agglomeration, so this should be used with care.
UserFeedSSA / SSA Input The seed surface area specified directly by the user. Any SSA value, if present, in the feed stream is ignored. Visible when Precip.Method is SSA.
SSAin Calc The current SSA value from feed stream.
SSAUsed Calc The SSA value used in the calculations as per the above inputs.
THA.Density Calc The THA species solids density (used in GrowthRate calculation).
Variables for the Fixed GrowthMethod
Precip.Rate Input The user specified precipitation rate.
Variables for the FixedRate GrowthMethod
FixedGrowthRate Input The user specified growth rate.
Variables for the White-Bateman GrowthMethod
ER_White Input The Activation Energy (E) divided by the Gas Constant (R).
K_White Input The Constant used in the Growth Rate Factor correlation.
gF_White Input This allows the user to tune the growth rate based on a factor.
Variables for the Veesler-Boistelle GrowthMethod
ER_VB Input The Activation Energy (E) divided by the Gas Constant (R).
K_VB Input Overall growth rate constant.
Beta.Critical Input Critical supersaturation (nominally 1), must be exceeded for growth to occur
N_VB Input Exponent g for relative supersaturation term [math](\beta-\beta_c)^g[/math]
Variables for the SSA Yield GrowthMethod
ActivationEnergy/R Input The Activation Energy (E) divided by the Gas Constant (R).
K0 Input The Constant used in the Growth Rate Factor correlation. Default value for K_0 is 2.2*1011. This value is typically tuned for plant conditions. It may need adjustment as additional terms described below are adjusted.
n_TOC Input Organics term = [math]e^{-n_{TOC} \quad \times \; TOC}[/math]. Using zero for n_TOC will remove TOC dependence.
n_s Input Total Soda effect = Sn_s. Using zero for n_s will remove the precipitation dependence on soda.
n_fc Input Free Caustic – Free caustic is the sodium hydroxide in solution that is not associated with dissolved alumina. KFreeCaustic = FCn_fc.Using zero for n_fc will remove the precipitation dependence on free caustic.
n_C Input Additional Caustic effect term Cn_C. The default value is zero.
n_AC Input This is the n factor for the supersaturation driving force term. [math] \left( \frac{A_{out} - A^*}{C} \right)^n [/math]. The default value is 2.
n_ssa Input Specific Surface Area, SSA. This correction accounts for the fact that the effective surface area for precipitation may not scale linearly with SSA. Kssa = SSAnssa. The default value for nssa is 1.0 (making precipitation rates linearly proportional to SSA).
GrowthMethod Results
kG Calc kG constant for the GrowthMethod
GrowthRateFactor Calc Product of kG and [math] e^{-E/RT} [/math]
GrowthRateR Calc Radial (i.e. crystal) growth rate. This is the growth rate term multiplied against particle surface area to determine precipitation rate. See Growth Rate Methods for more details.
GrowthRateD Calc Diametric (i.e. particle) growth rate. GrowthRateD = 2 x GrowthRateR
Precip Heat of Reaction
UserHOR Tickbox Option for User to enter Heat of Reaction for Gibbsite Precipitation reaction (kJ/kg-Gibbsite). The default value is -252.3 kJ/kg-Gibbsite at 0°C. NB this is an exothermic reaction and energy is released as Gibbsite precipitates. For reference, please refer to Heat of Dissolution of Gibbsite and Boehmite
User.GibbsiteHOR@0C Input The Gibbsite precipitation HOR value to be used. Only available when UserHOR is selected. NB a positive entry generates a warning message as the HOR shold be negative. For reference, please refer to Heat of Dissolution of Gibbsite and Boehmite
GibbsiteHOR@0C Calc The Gibbsite precipitation HOR value used. -252.3 kJ/kg-Gibbsite at 0°C if UserHOR is not selected. For reference, please refer to Heat of Dissolution of Gibbsite and Boehmite

Bound Soda Calculations

BoundSodaMethod
(Not visible with Fixed GrowthMethod)
Ohkawa Ohkawa, Tsuneizumi and Hirao [5] method with corrections for bound soda as Na2O and NaOH* - now the default method. See Bound Soda Theory for information.
Hunter Armstrong, Hunter, McCormick and Warren. [6] correlation, see Bound Soda Theory for information.
Fixed % Calculates a fixed percentage of soda co-precipitation with the precipitated hydrate. This specifies soda as NaOH as a mass fraction of alumina as THA
K_tuneBS Input The tuning factor for the bound soda calculation.
K1 Input The soda factor. The default value is 1.27*10-3.
E_SODA Input Constant used in the bound soda calculation, default is 2535 K-1
BoundSodaFrac Input Visible when BoundSodaMethod is set to Fixed. The user specified bound soda fraction.
BoundSodaSpecies Text Display the bound soda species used for occlusion. If NaOH* is present, it will be used, if not, the project will use Na2O. If neither is present, the project will force add Na2O(s) to the species list.
BoundSoda_OrgPart Input The percentage of bound soda precipitated as organics. If the bound organic species is not present in the project, a warning message: Organics precipitation and BoundSoda_OrgPart not available:Matching bound organic solid for Na2C5O7(aq) not found will be given. See Bound organics and Bound Soda implementation for more information.

Oxalate Calculations

OxalatePrecip None No oxalate co-precipitation occurs.
Fixed Oxalate co-precipitation will occur at a user specified fixed rate.
Supersaturation The oxalate supersaturation form uses a driving rate proportional to the square of the oxalate supersaturation above an optional metastable value.
Please note that this is only a made up equation with no theory or experimental data to support it. It is added here so the precipitation can be varied based on the tank conditions.
For users with their own correlation data, it will be highly recommended to calculate the rate using general controller or MP file, then set the oxalate precipitation rate using the Fixed Method.
See Oxalate Precipitation Theory for more information.
McKinnon McKinnon, Parkinson and Beckham [8] equation, see Oxalate Precipitation Theory for information. Available in 138 or later.
OxalateReqd Input Visible with OxalatePrecip set to Fixed. User defines the amount of oxalate precipitation as a fixed amount. If user correlation is available, the oxalate precipitation can be calculated in a PGM or MP file using the correlation, then set the calculated rate here.
OxSSatReqd Input Oxalate supersaturation fraction (Ox / Ox* - 1) required for oxalate precipitation, used to account for metastability. Used by the Supersaturation method.
OxSSatK Input Constant used by the Supersaturation oxalate precipitation method.
OxalateRateFactor Input Oxalate precipitation rate tuning factor used by the McKinnon method.

Solution Convergence

(Not visible if using Batch Mode)

UseLastConverged Tickbox If selected, will restart solution iteration at last converged state. If the solution is nearly converged, this will speed up the iteration. If the solution was converged, and nothing else is changed it should immediately converge.
Convergence.Limit Input Global tolerance for testing convergence for iterative calculation in all precipitator tanks. Default is 1.0e-8.
Thermal.Damping Input Damping for energy convergence. Default of 0.
Mass.Damping Input Damping for mass convergence. Default of 0. This value may need to be increased, often significantly 80% plus, for a precip tank with a significant change. Try increasing this when failed to converge error message is shown.
Ext.FlowDamping Input Damping for external cooling volume flow convergence when using external cooling. Default of 0.
ClassifierError Tickbox Include classifier recycle in overall convergence
NumberErrors Tickbox Include PSD numbers in overall convergence
PSDErrScale Input Relative Contribution of PSD Error
MinIterations Input Minimum number of iterations for the convergence loop.
MaxIterations Input Maximum number of iterations for the convergence loop.
Iterations Calc Number of iterations solved.
Yield Error Calc Error in convergence of yield calculations
PSDError Calc Error in convergence of particle numbers.
ClassifyError Calc Error in convergence of classifier recycle.
TotalError Calc Total Error.

Dynamic Time Step

(Options for additional internal iterations at smaller time steps for dynamic calculation. Allows for higher precision precipitation in projects with large step sizes. Note: This may cause increased project solve time. Dynamic Only)

Safety.TimeStep Iteration Count Use a specified number of internal time steps.
E.g. if the Dynamic Solver Step Size is 300s and IntegrationSteps = 5, then 5 internal time steps of 60s each will be used.
Max Time Step Use a specified maximum internal time step. The number of internal iterations will depend on the Dynamic Solver Step Size. Input value is local to the tank.
E.g if the project time step is 300s and MaxTimeStep = 120s, then 3 internal time steps of 100s each will be used.
Max Time Step Global As with Max Time Step but the input value is global.
IntegrationSteps Input Input for Iteration Count.
MaxTimeStep Input Local input for Max Time Step.
Global.MaxTimeStep Input Global input for Max Time Step Global.
IntegrationStepsUsed Calc The number of internal time steps used. Visible with MaxTimeStep or Global.MaxTimeStep.

Thermal and Mass Balance

Env.Thermal.Loss Calc The amount of energy lost to the environment.
Evap.Mass.Loss Calc The evaporation mass rate
Evap.Thermal.Loss Calc The amount of energy lost through evaporation.
Batch.Evap (only visible if both the BatchMode and Evaporation options are ON)
Feed.Evap.T Calc the PGL feed temperature after evaporation (only visible if both the BatchMode and Evaporation options are ON)
Feed.Evap.DeltaT Calc the temperature drop in the feed stream (only visible if both the BatchMode and Evaporation options are ON)
Cooler.Thermal.Loss Calc The amount of energy transferred through the cooler.
Total.Thermal.Loss Calc Total amount of energy loss: Evap + Env + Cooler.
ReactionHeat@0 Calc The amount of energy released by the precipitation reaction at the 0dC temperature.
ReactionHeat(@T) Calc The amount of energy released by the precipitation reaction at the product temperature.

Stream Enthalpy

HzIn Calc Enthalpy flux into Precipitator.
HzEvap Calc Enthalpy flux to Evaporation.
HzOut Calc Enthalpy flux of the product stream. If classifier option is being used, then this will only show the overflow stream, the underflow stream will be shown in UF.HzOut.
UF.HzOut Calc Enthalpy flux of the underflow stream. Only visible if classifier option is being used.
HzBal Calc Enthalpy out minus enthalpy in. This is the net of heat transfer, evaporation loss and reaction heat (NB Rxn heat measured at 0°C reference temperature).
FeedHf Calc The total energy of the feed.
ProdHf Calc The total energy of the product.
EvapHf Calc The total energy of the material evaporated from the precipatator, if evaporation is used.

Cooler Tab

Tag (Long/Short) Input / Calc Description/Calculated Variables / Options

FOR EMBEDDED COOLING OPTION

Cooler.On tick box Switches the cooler on/off
Cooling.Type Fixed.dQ User specifies the energy change required.
Fixed.dT User specifies the temperature change required.
HeatExchange User specifies the HTC, Area and flow for heat exchange.
Variables for the Fixed.dQ method
dQ Input The user specified change of energy.
Variables for the Fixed.dT method
dT Input The user specified change of temperature.
Variables for the HeatExchange method
HX.Area Input The user specified heat transfer area.
HX.HTC Input The user specified heat transfer coefficient.
By.Vol.Flow tick box Slurry to "cooler" can be specified in mass or volumetric flows
Heat Exchanger
Cooling.MassFlow / Cooling.Qm Input / Calc The slurry mass flow to be cooled by the "cooler". Input allowed when By.Vol.Flow is not selected.
Cooling.VolFlow / Cooling.Qv Input / Calc The slurry volumetric flow to be cooled by the "cooler". Input allowed when By.Vol.Flow is selected.
Hx.UA Calc heat exchanger UA.
Hx.LMTD Calc heat exchanger log mean temperature difference.
Liquor.Tin Calc The slurry temperature into the "cooler".
Liquor.Tout Calc The slurry temperature out of the "cooler".
Coolant
Water.Flow Calc Displays the CW mass flow into the "cooler" via the Cool_in connection.
Water.Vol.Flow Calc Displays the CW volumetric flow into the "cooler" via the Cool_in connection.
Water.Tin Calc Displays the CW temperature into the "cooler" via the Cool_in connection.
Water.Tout Calc Displays the CW temperature out of the "cooler" via the Cool_out connection.
Cooling.Rate Calc The rate of cooling.

FOR EXTERNAL COOLING OPTION

By.Vol.Flow tick box Slurry to "cooler" can be specified in mass or volumetric flows
Ext.Cooling.VolFlow / Ext.Cooling.Qv Input / Calc Input or displays the mass flow into the external cooler via the Cool_in connection, depends on the By.Vol.Flow option.
Ext.Cooling.MassFlow / Ext.Cooling.Qm Input / Calc Input or displays the mass flow into the external cooler via the Cool_in connection, depends on the By.Vol.Flow option.
Ext.Cooling.Temperature / Ext.Cooling.T Calc The temperature of the "cooled" side stream returning to the precipitator.
Ext.Cooling.TotHzOut Calc The total energy of the side stream leaving the precipitator.
Ext.Cooling.TotHzIn Calc The total energy of the side stream returning to the precipitator.
Cooling.Rate Calc The rate of cooling.

PSD Tab

Only visible when Precip.Method = PSD. Please See Precipitation using Full PSD for more information on theory and method.

Tag (Long/Short) Input / Calc Description/Calculated Variables / Options
PSDDefinition List Box Any predefined PSD definition in the project configuration file can be selected from this list.

PSD Control

Growth.On Tick Box Selecting this will enable growth rate calculation. Please see also Growth Rate Methods
Agglom.On Tick Box Selecting this will enable agglomeration calculation. Please see also Implementation of a size dependent kernel
Necleation.On Tick Box Selecting this will enable nucleation rate calculation. [math] N = 5.0\times 10^8 \left(\frac{A-A^*}C\right)^2\sigma[/math]
SodaWithNucleation Tick Box When this option is ticked, the bound soda calculations will be based on the total yield (growth + nucleation). If this is not ticked, the nucleation yield will be excluded in the bound soda calculations.
NonPSDSolids Tick Box Selecting this will include Non THA Solids in PSD Mass
AllSolidsDensity Tick Box Selecting this will include Non THA Solids in PSD Density
SeedPSD Tick Box Selecting this will allow SysCAD to auto generate a small quantity of seed if NO THA solid was found in the Precipitation Feed. The generated amount will be sufficient to seed a tank and allow precipitation to occur in the tank. When solids returns to the tank via the proper seed streams, the recycled solids will take over and SysCAD will no longer generate any extra solids. See Using the Full PSD model.
Area.Correction Input Scaling for nonsphericity. See Area Correction

PSD Display

ShowRates Tick Box Selecting this will enable the display of Particle Size Number Data Table on the PSD tab. Please see Show Rates
DisplayAsFraction Tick Box When this option is ticked, the rates (Growth, Agglo etc) are normalized by dividing by the particle numbers: that is, displayed as a fraction of the particle number.
ShowAgglomKernel Tick Box Global option to show Kernel tab with agglomeration kernel beta terms. Note these values are the "raw kernel" before the inclusion of agglomeration rate or collision effects.
TrackUltrafines Tick Box Warn if mass is present in smallest size bin - this is moved to next bin up.

Agglomeration Parameters

Agglom.Kernel.Type Size Independent Ilievski size independent kernel (Light Metals, 1982). This assumes that all interactions are equally likely to cause an agglomeration event (i.e. beta = 1 for all size combinations). This option is typically paired with Agglom.Rate.Type Supersaturation.
Ilievski The kernel is of the form: [math] \frac {1}{D_{i}+D_{j}}[/math]. See Size Dependent Kernel for more information. This option is typically paired with Agglom.Rate.Type of form Growth/Beta4.
From Build 139, this is the default selection and [math]D_{i}+D_{j}[/math] is replaced by [math]2.\sqrt[m]{\frac{1}{2}(D_i^m+D_j^m)}[/math], twice the Generalised Mean of the interacting particle sizes with power [math]m[/math] (Agglom.GenMeanPow). At default [math]m=1[/math] this is simply the sum.
User This option allows manual input of the agglomeration kernel on the dKernel tab.
Kernel Builder Enables the Kernel Builder, available on the dKernel tab.
Agglom.Rate.Type Constant The calculated agglomeration rate is set to 1, so in effect agglomeration rate is set directly using Agglom.Rate.Correction. This is equivalent to the option Agglom.RawKernel prior to Build 139.
Supersaturation The agglomeration rate is governed by a single equation dependant on temperature and liquor properties. Agglomeration rate is in the form: [math] 1.77\times 10^{-4} \times \left(\frac{A-A^*}C\right)^4[/math] . This option is typically paired with Agglom.Kernel.Type Size Independent.
Growth/Beta4(T) The agglomeration rate is of the form: [math] \frac {G^n}{\beta_4(T)}[/math] where the calculated [math]\beta_4[/math] is a function of Temperature only. See Size Dependent Kernel for more information. This option is typically paired with Agglom.Kernel.Type Ilievski. From Build 139, this is the default selection.
Growth/Beta4(T,Sh) The agglomeration rate is of the form: [math] \frac {G^n}{\beta_4(T,Sh)}[/math] where the calculated [math]\beta_4[/math] is a function of Temperature and Shear Rate. See Size Dependent Kernel for more information. This option is typically paired with Agglom.Kernel.Type Ilievski.
Agglom.Collision.Type Restricted-in-Space This option assumes a particle can only interact with particles in its immediate vicinity, restricting the number of possible collisions. Applies a division by total particle count [math]N_T[/math] . See Free-in-Space vs Restricted-in-Space.
Free-in-Space This option assumes the agglomeration rate is proportional to the total number of possible collisions between particles, any particle is free to collide with any other particle. Applies a division by 109 (or 1012 prior to Build 139) to maintain a similar order of magnitude as Restricted-in-Space. See Free-in-Space vs Restricted-in-Space.
Agglom.UseCorrectedCollision Tick Box Added in Build 139 for backwards compatibility (may be visible if upgrading projects). Simplifies the FIS and RIS corrections, as described above. Recommend this box be checked and model retuned as necessary.
Agglom.SolidsFracPow Input Power term for effect of solids volume fraction on agglomeration rate. Default 0.
Agglom.GrowthRatePow Input Used with Agglom.Rate.Type of form Growth/Beta4. Power term for effect of growth rate on agglomeration rate. Default 1.
Agglom.Cutoff Tick Box If selected, then particles greater than Agglom.Cutoff.Size will not agglomerate.
Agglom.Cutoff.Size Input Maximum size for agglomerating particles. Only visible when Agglom.Cutoff is selected.
Agglom.Cutoff.Used Input Actual size used for agglomerating particles. Only visible when Agglom.Cutoff is selected.
Agglom.GenMeanPow Input Available with Agglom.Kernel.Type Ilievski. Power term for Generalised Mean of particle size interactions. Default 1 to give arithmetic mean (i.e. proportional to sum).
Agglom.CalcBeta4 Tick Box Used with Agglom.Rate.Type of form Growth/Beta4. Calculate (On) or user supplied (Off) [math]\beta_4[/math] in the Agglomeration Kernel equation.
Agglom.UserBeta4 Input Used with Agglom.Rate.Type of form Growth/Beta4. User specified [math]\beta_4[/math] for use in the Agglomeration Kernel equation. Only visible when Calc.Beta4 is not selected.
Agglom.Beta4 Result Used with Agglom.Rate.Type of form Growth/Beta4. [math]\beta_4[/math] in the Agglomeration Kernel equation. See Size Dependent Kernel
Agglom.Rate.Magnitude Input Overall correction of magnitude for Agglomeration calculations *10n. Default hidden, value 0. Used for coarse tuning only.
Agglom.Rate.Correction Input Overall correction rate for Agglomeration calculations.
Agglom.Rate.FineTuning Input Overall correction rate for Agglomeration calculations. Default hidden, value 1. Recommend to keep this term around 1.0 and use for localised fine-tuning.

Nucleation Parameters

Misra.Nucleation.Rate Input Nucleation Rate term. See Nucleation
Nucl.Rate.Correction Input Correction for Nucleation calculations

Results

Growth.Rate Calc Diametric (i.e. particle) growth rate. Same as GrowthRateD on the Precip tab.
Agglom.Rate Calc The total agglomeration rate factor determined by the selection of Agglom.Rate.Type and Agglomeration.Collision.Type (and associated inputs) as well as Agglom.Rate.Magnitude and Agglom.Rate.Correction. This term is multiplied with the kernel and particle sizes at each particle size combination. See Model Theory - Agglomeration.
Agglom.Degree Calc The degree of agglomeration at -45μm. Calculated as [math]\frac{[-45μm]_{Feed} \quad - \; \; [-45μm]_{Prod}} {[-45μm]_{Feed}}[/math]
Nucleation.Rate Calc Net rate of increase in particle numbers due to nucleation.
GrowthYield Calc The Growth Yield. Total new mass of THA in tank due to Growth.
Nucleation.Yield Calc The Nucleation Yield. Total new mass of THA in tank due to Nucleation.
NumMassIn Calc Mass of PSD Solids into the Precipitation Tank (Excludes Non-PSD solids).
NumMassOut Calc Mass of PSD Solids leaving the Precipitation Tank.

Results (Particle Numbers)

NumbersByMassIn Calc Number of particles per mass of slurry entering the Precipitation tank.
NumbersByMassOut Calc Number of particles per mass of slurry leaving the Precipitation tank.
NumbersByMassDelta Calc The number of particles generated in the Precipitation tank per mass of slurry in the tank.
NumbersByVolIn Calc Number of particles per volume of slurry entering the Precipitation tank.
NumbersByVolOut Calc Number of particles per volume of slurry leaving the Precipitation tank.
NumbersByVolDelta Calc The number of particles generated in the Precipitation tank per volume of slurry in the tank.
NumbersBySolidsOut Calc The number of particles generated in the Precipitation tank per mass of PSD solids in the tank.

If ShowRates is selected, the following matrix of data with rates and numbers is shown:

Tag (Long/Short) Description/Calculated Variables / Options

Particle Size Numbers Data

Particle Size Interval Particle size interval as defined in the project configuration file. See Setting up the PSD Definition
MidSize [math]Geometric Mean_i = \sqrt{d_i * d_{i-1}}[/math], See Geometric Mean for more information.
#/kg Sl in Particle numbers in incoming slurry
#/kg Sl tank Particle numbers in the tank
GrowthRate Net rate of increase in numbers due to growth
GrowthRate+ Rate of increase in numbers due to growth in from smaller bins
GrowthRate- Rate of decrease due to growth out to larger bins.
AgglomRate Net rate of increase in numbers due to agglomeration
AgglomRate+ Increase in numbers due to agglomeration from smaller bins
AgglomRate Decrease due to agglomeration to larger bins
Tot.Rate Agglom + Growth + Nucleation rates
Rate*ResT Tot.Rate times Residence Time.
Ascending / Descending Use the Ascending or Descending button to change the display order of the table.

Notes:

  • The model ignores particles in the smallest bin (passing the smallest size), and will never create particles in this size. The feed may have particles of this size if the PSD is created using eg the Rosin-Ramler distribution. The TrackUltrafines option will warn when ultra-fine particles are present, and move them to the next smallest bin.

dKernel and Kernel Tabs

Only visible when Precip.Method = PSD.

Kernel tab only shown when ShowAgglomKernel is selected. This shows the full array of [math]\beta[/math] kernel values.

dKernel tab only shown when Agglom.Kernel.Type = User or Kernel Builder. With Agglom.Kernel.Type = User, [math]\beta[/math] values are manually entered for the entire agglomeration kernel.

With Agglom.Kernel.Type = Kernel Builder, the following fields are available for building a custom kernel function. See Kernel Builder for more details.

Form of each term: [math]a.\left(\cfrac{f(L_i,L_j,[m])}{b}\right)^n+c[/math]

Tag (Long/Short) Input / Calc Description / Calculated Variables / Options
Kernel.Terms Input The number of terms in the agglomeration kernel calculation.
Kernel.Factor Input Overall correction factor for the calculated agglomeration kernel. Typically used to correct magnitude. Note that this term is optional, and has the same effect as Agglom.Rate.Correction.
The following are repeated for each Kernel.Terms. Note that Term# is replaced with Term1, Term2, etc.
Kernel.Term#.Type

Form of [math]f(L_i,L_j,[m])[/math]
Sum Sum of powers [math]L_i^m + L_j^m[/math]
Difference Difference of powers [math]L_i^m - L_j^m[/math]
Product Product [math]L_i.L_j[/math]
Maximum Size of larger particle [math]L_i[/math]
Minimum Size of smaller particle [math]L_j[/math]
Mean Generalised mean [math]\sqrt[m]{\frac{1}{2}(L_i^m+L_j^m)}[/math]
Kernel.Term#.Power Input Overall power n.
Kernel.Term#.PowerB Input Only available with Sum, Difference and Mean. Power on individual terms m.
Kernel.Term#.Coefficient Input Coefficient a.
Kernel.Term#.Divisor Input Divisor b.
Kernel.Term#.Constant Input Constant c.
Kernel.Term#.Denominator Tick Box Whether the term appears on the numerator (off) or denominator (on) of the kernel calculation.

Classif Tab

Only visible when Classification tick box is selected. The full Solid-Liquid Separator is used for General Separator and Evaporator, please see Solid-Liquid Separator for more information on theory and method. The Classification sub model uses most of the solid-liquid separator features. Difference and extra fields are documented here.

Tag (Long/Short) Input / Calc Description / Calculated Variables / Options

Requirements

SplitMethod Solid Separation This is the only available option as the embedded classifier will separate and recycle solids to meet target underflow solids concentration.
Requirements (Solids / Liquids Separation) Please see Solid Separation for all Solid Separation Methods.
The following is available when SolidsSeparaMethod = SolidsPSD.
SolidMethod Whiten This method is based on a model proposed by Whiten. See Whiten for information.
Karra This method is based on a model proposed by V.K Karra and is only valid for screen cut apertures greater than 1mm. See Karra for information.
Rosin-Rammler This method is based on a Rosin-Rammler type of function with the efficiency curve expression derived by Reid and Plitt. See Rosin-Rammler for information.
Lynch This method is based on a Lynch type of function. See Lynch for information.
DelVillar-Finch This method includes a term for the "fish hook" effect for entrainment. See DelVillar-Finch for information.
Partition Curve PartCrv Tab will open where user can define the Fraction of Feed Solids per size interval reporting to the oversize.
Selected Solid Species Calculation Method

This section is used to set species Bypass options, (such as setting oxalate to bypass to O/F) , see Bypass Options for more information.

Results

Temperature Calc The temperature of the material leaving the classification section.
MassFlow / Qm Calc The mass flow feeding the classification section, this includes the internal recycle.
VapourMassFlow / VQm Calc The total flow of vapour to the Underflow and Overflow streams.
UF.BypassMassFlow / UF.BypassQm Calc The mass flow of the material that bypasses the underflow.
OF.BypassMassFlow / OF.BypassQm Calc The mass flow of the material that bypasses the overflow.
BypassMassFlow / BypassQm Calc The mass flow of the solids in the unit that bypasses the separation section.
UF.SolidsTakeoffQm Calc The internal solids recycle amount, displayed as solids mass flowrate. This is equivalent to the solids recycle stream on the Left image in Classification theory.
UF.SolidsTakeoffFrac Calc The internal solids recycle amount, displayed percent solids recycled. This is equivalent to the solids recycle stream on the Left image in Classification theory.
UF.FinalSolidFrac / UF.FinalSF Calc The final underflow solids fraction. This is after the recycle, thus the final underflow leaving the precipitation unit going forward.
Separation Results
UFSolidsRecovery Calc This is the internal classifier's underflow solids recovery, this is BEFORE the solids split to recycle. This is equivalent to the Classifier on the Left image in Classification theory.
UFLiquidRecovery Calc This is the internal classifier's underflow liquid recovery, this is BEFORE the solids split to recycle. This is equivalent to the Classifier on the Left image in Classification theory.

Content and Preset Tabs (Dynamic Only)

Content Tab: These displays the tank contents (total mass, volume, properties etc) in the standard Tank access window format.

Preset and DSp Tabs: allow the composition and contents to be preset.

Batch Tab (Probal Only)

Batch mode simulates a tank which is filled with separate PGL and Seed feed streams, allowed to precipitate, and then drained. In practice, a plant would have a number of tanks at different stages of the fill/precip/drain cycle, and the net operation is steady state; the contents of the product stream being determined by the composition at the end of batch cycle, and the flow rate determined by the total feed.

See Batch Mode for a more information.

Tag (Long/Short) Input / Calc Description/Calculated Variables / Options

Batch Operating Parameters

TankCount Input Number of Batch Tanks in the Precipitation bank (need not be integer)
Level.SetPoint / Level.Spt Input Operating Level of Batch Tank
PGL.VolFlowReqd / PGL.QvReqd Input PGL Fill Rate. The fill rate parameters can be different to actual PGL flow rates. If they are less, then we are filling multiple tanks simultaneously. If they are greater, then we are filling rapidly from a holding tank which is continuously filled from the feed streams.
Seed.VolFlowReqd / Seed.QvReqd Input Seed Fill Rate. The fill rate parameters can be different to actual seed flow rates. If they are less, then we are seeding multiple tanks simultaneously. If they are greater, then we are filling rapidly from a holding tank which is continuously filled from the feed streams.
Seed.Overlap Input Overlap of PGL and Seed. See Description of Batch Cycle for an illustration of fill time.
Drawoff.VolFlowReqd / Drawoff.QvReqd Input Drawoff Rate.
Drawoff.Overlap Input
MaxResidenceTime Input Maximum residence time in a batch tank.
WaitTime Input After draining, there may be a specified wait time before filling starts again

Feed Flow Conditions

PGL.VolFlow / PGL.Qv Result Volume Flow of PGL.
Seed.VolFlow / Seed.Qv Result Volume Flow of Seed.

Calculated Cycle Times

Seed.Time Result Total Time spent seeding.
Drawoff.Time Result Total Time spent in drawoff.
Recirc.Time Result Total Time spent in precipitation.
AvailableCycleTime / Cycle.Time Result Overall Cycle Time. (Batch Cycle Done)

Waypoints: PGL Filling starts at t=0

PGL.EndTime Result PGL flow stopped.
Seed.StartTime Result Seed flow started.
Seed.EndTime Result Seed flow stopped.
Drawoff.StartTime Result Drawoff started.
Drawoff.EndTime Result Drawoff stopped.
TankFlowTime Result Feed Time per tank.

Levels during fill

SeedEndFirst Result Returns true if the Seed period ends before PGL filling.
Seed.StartLevel Result Level when seed started.
PGL.EndLevel Result Level when PGL stopped.
Seed.EndLevel Result Level when Seed stopped - generally equal to level setpoint.

Tank Masses

Seed.Mass / Seed.Mt Result Total Mass of Seed to tank.
Seed.Volume / Seed.Vt Result Total volume of Seed to tank.
Seed.SolidMass / Seed.SMt Result Total Solid Mass of Seed to tank.
PGL.Mass / PGL.Mt Result Total Mass of PGL to tank.
PGL.Volume / PGL.Vt Result Total volume of PGL to tank.
Total.Mass / Total.Mt Result Total Mass of PGL and Seed to tank.

Cooling

MinLevel Input Level where cooling is started/stopped.
Tank.VolFlow / Tank.Qv Input Flow of Cooling Water to Heat Exchange. This is the per tank cooling water flow.
Total.VolFlow / Total.Qv Result The calculated cooling water flow is determined by the batch model and the specified per tank cooling water flow. For correct prediction of the cooling water return temperature, the actual cooling water flow should be set to this calculated number. See Cooling form more inforamtion.
StartTime Result Cooling Initiated.
EndTime Result Cooling Ended.
Tank.TotalHeatXfer Result Batch Cycle Total Heat Transfer per Tank
Tank.AverageHeatLoad Result Batch Cycle Average Cooling Load per tank
Total.HeatLoad Result Total Cooling Load for all Tanks

EHX

Tank.TotalHeatXfer Result Batch Cycle Total Environmental Heat Loss per tank
Tank.AverageHeatLoad Result Batch Cycle Average Environmental Heat Loss per tank
Total.HeatLoad Result Total Environmental Heat Loss for all tanks.

Batch Control

Fill Steps Input Number of timesteps for fill. (Note: The default batch control parameters give sufficient accuracy for modelling.)
Recirc Steps Input Number of timesteps for recircirculation.
Drawoff Steps Input Number of timesteps for drawoff.

Cycle Tab (Batch Mode)

Tag (Long/Short) Row / Column Heading Description

Batch Data

T1 to T65 Row Heading Time segments during a batch cycle, for each time segment, the following data are displayed.
Time / t Col Heading Time from start of filling
AC Col Heading The ratio of A:C, where A is NaAl[OH]4 concentration, expressed as grams of Al2O3 /L liquor and C is Caustic concentration in NaOH + NaAl[OH]4, expressed as grams Na2CO3/L liquor.
Solids Col Heading solids concentration.
Temp / T Col Heading tank temperature
Lvl Col Heading tank level
HX Col Heading cooling heat transfer
Rx Col Heading precipitation reaction heat
EHX Col Heading environmental heat transfer
SeedSol Col Heading seed solids flow
PrecSol Col Heading solids precipitation
PrecTHA Col Heading THA precipitation (excludes other solids)
TotSol Col Heading tank solids content - cumulative seed + precipitated solids
TotHt Col Heading total heat transfer (cooling + environmental heat transfer)