The Distillation_Column is a separation equipment which simulates a rigorous multi-stage multi-component single distillation column. It allows up to four feeds connected to different stages of the column and up to two optional side extractions. Total or partial condenser and partial reboiler are implemented. When partial condenser is selected, the distillate is withdrawn  vaporized. Murphree efficiency allows for non-equilibrium behavior on each stage. The total condenser and the reboiler are considered equilibrium stages and therefore the Murphree efficiency is taken 1.        The liquid and vapor phases flow rates and properties are listed in the Report tab and can be optionally exported in a text file format by click on the Export to .txt File button.       The Sizing tab optionally calculates the diameter, height and tray layout parameters for the maximum vapor loaded tray by click on the Evaluate Diameter & Height button. The calculations can be optionally exported in a text file format by click on the Evaluate &  Export All button. At least one run of the column is needed to accomplish these.             At least one feed stream should be connected and filled with solvents at Feed1, Feed2, Feed3 or Feed4 connector. The Distillate_Out, Bottom_Out and the utilities streams Coolant_In, Coolant_Out, Steam_In, Condensate_Out are not optional. The Input Data and Side Streams Tabs should be properly filled in before run. What do you want to see? Data Description Equipment Properties Example Method&Equations Warnings Errors

Data Description

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Equipment Properties

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Input Data tab. Specifies the main input data for the equipment.  No of Stages mandatory dialog box represents the actual number of stages (trays) inside the column. The condenser and the reboiler are not taking into account.  Reflux Ratio mandatory dialog box represents the fraction of the top product returned from the condenser as liquid phase on the upper tray inside the column.  Distillate Rate mandatory dialog box represents the total flow rate extracted as top product.  Heat Losses mandatory dialog box represents the total heat loss of the column as fraction of the reboiler heat duty.  The distillate will be delivered as liquid phase at boiling point if Total Condenser is selected or vaporized, if Partial condenser is selected.  The Initial Estimates for the column profiles used by  the solver algorithm are displayed in the Stages dialog grid. You can modify any value and then click the Refresh button with the mouse or select it with [TAB] and press [ENTER].  To fill a column with the same value you have to select the desired parameter in the Fill Grid Column combo box, input the value below and click the Refresh button.  Increasing the number of Max Iterations the computational time will increase. Decreasing it, the model might not converge. The final results are the ones obtained at the end of the last iteration.

Side Streams tab. Specifies the input data for the side streams actually connected to the equipment.   At least one feed stream should be connected to the equipment. Then the appropriate mandatory dialog box should be filled with assigned number of stage to the connected streams. Maximum 4 feed streams can be connected. The feed connectors are placed on the same side of the equipment.   Maximum 2 optional Side streams can be connected to the equipment to extract distillation product from intermediate stages, either from the liquid or from the vapor phase. The Side Draw 1 from Stage No. and Side Draw 1 from Stage No. are mandatory dialog boxes. They should be filled in to may perform an appropriate run of the equipment, if side streams are connected.

Reports tab. Display the output results and column parameters profiles from the distillation process calculation. The grid display the mass flow rates on each tray: total flow, liquid phase flow, vapor phase flow, each solvent flow and cumulated total flow of all the other components if exist. The units of measure are displayed at the bottom of the grid.   Select either Mole Basis or Mass Basis

Chart tab. Display a number of output column parameter profiles in a friendly graphical form. The following parameters' profiles: Temperature, Pressure, Total Loading, Liquid Loading, Vapor Loading can be selected in the combo box.  The Temperature parameter is selected by default.    The enhanced features of the chart can be selected from the tool bar. Chart saving, printing, copying to the Clipboard in several formats to export in other applicatications, font type and format changing, Data Editing, 3D/2D display, gallery options and help using the chart are now available.

Sizing tab. Display the general input data for the hydraulics and layout of the trays inside the column, Sieve, Valve or Bubble Cap input parameters and the caclulated data.   Cross-flow trays with segmental straight or sloped downcomers are considered.   The column inside dimeter  is calculated based on the input fraction of the flooding vapor velocity and the downcomer to tray area fraction.   Leaving blank the Tray diameter dialogue box, the program will estimate the appropriate inside diameter rounded to the above 0.5 ft based on semiempirical and hydraulic correlations. Inserting the desired value, the other calculations will be perform with this input value.   Fair, Kister & Haas and Smith correlations are available for the flood correlations.   Common industrial values can be selected in combo boxes for the Tray spacing and Tray deck thickness.   1 to 5 No of liquid passes can be selected on the cross section of the tray to establish the tray layout.   The System factor is an empirical parameter which takes into account the foaming tendency of the liquid system. The value of 1 is taken for non-foaming liquids. If values are available for the Top inside space above the first tray or Bottom inside space below the last tray, they can be filled in the appropriate dilogue boxes. Leaving them blank, a default 15% supplementary void space with a top to bottom height ratio of 2/3 will be assumed by default.   A click on the Evaluate Diameter & Height button will display in the Sizing Results frame the main sizing and hydraulic parameters for the maximum vapor loaded tray inside the column.   A click on the Evaluate and Export All button will display all the calculated values for each tray inside the column in a text file. The file can be saved or exported in other applications with Select, Copy and Paste options.   The Sizing section is recommended to be studied after the operating condition of the column have been established. The Sizing section uses the results obtained after the run of the column, but it can be seen as an independent option.

The tray layout drawings explain the significance of the parameters used in this section. The flow path length and different areas are detailed for 1 to 5 liquid passes across the tray.

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Example of using equipment

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Method&Equations

• The Distillation_Column equipment simulates the separation of volatile component that takes place in a single distillation column.

• The Boiling Point (Wang & Henke) multi-stage multi-component rigorous algoritm is implemented.
• The required input data are at least 1 and up to 4 feed streams (numbered from top to bottom) containing volatile solvent mixtures, the number of actual stages inside the column, the liquid reflux ratio returned from the condenser to the first stage inside the column and the distillate rate, expressed in kg-moles/hr to be extracted as top product. 
• Up to 2 optional side extractions can be connected to the equipment.
• The total number of stages should be specified in the Input Data tab. In the Side Streams tab each feed needs to be assigned to a stage number. Two feeds cannot be assigned to the same stage. The side extraction stages, flow rates in kg-moles/hr and the phase from which each stream is extracted should be specified in the Side Stream tab.
• The Input Data grid contains the first guess values for the column solver algoritm for pressure, Murphree efficiency, temperature, liquid and vapor flows (in kg-mole/hr) on each tray inside the column. These values can be modified on each stage.  An Automation frame helps the user to fill the same value on each stage by selecting the desired parameter in the Fill Grid Column combo box, inserting the value in the cell below and giving a click on the Refresh button
• Based on the Coolant Out Temperature, Heating Out Temperature and Heat Losses fraction from the Input data tab, the Steam Per Feed, Condenser and Reboiler Duties and Heat Losses are calculated and displayed in the Reports tab. The actual Reflux Rate is calculated and displayed in the Reports tab. The results are expressed in the units of the case model.
• The calculated parameters are displayed in the report grid for each stage. A click on the Export to .txt file will display the column profile in a text file displayed on the screen.
• A 2D or 3D chart will display the column profile for the following parameters: Temperature, Pressure,Total loading, Liquid and Vapor loadings based on the selection made in the combo box from the Chart tab. The Temperature parameter is selected by default.
• A separate sizing module will optionally calculate the diameter and height of the column, together with hydraulic and tray layout parameter. Sieve, Valve or Bubble cap trays can be selected, Fair, Kister & Haas or Smith flodding correlation are available and straight or sloped downcomers can be performed.
• Leaving blank the Tray diameter cell will calculate this value based on the Flood fraction, Flood correlation and Downcomer Area to Tray Area ratio input values. Otherwise the input value will be used to calculate the other parameters on each tray. Leaving blank both the Top and the Bottom Column heights zones will calculate these values based on a 15% volume supplement for the zones above the upper tray and below the lowest tray in the column. The top to bottom height default ratio of 2/3 is considered.
•  After the convergence of the equipment the Sizing tab will perform the calculation by using either the Evaluate Diameter & Height button or the Evaluate & Export All button.  In the first case the diameter will be calculated considering the maximum vapor loaded tray inside the column. In the second case, all the trays will be separately calculated and the results will be exported in a text file displayed on the screen.
• A number of helpful warning messages regarding good engineering practice or exceeding of the sizing correlation limits are displayed specifically for each tray either in the Run output window or at the bottom of each tray sizing calculation in the exprted file
• The bottom recirculation flow temperature is the saturated vapor temperature for the bottom product mixture.
• If are not specified, the cold and the hot utility are used by default:

• Heat duty taken by the condenser is calculated as:

       Qcond = (Toph - Dh) * (D + R)

                where:

       Qcond is the heat duty taken by the condenser

       Toph is the enthalpy of the top stream (inlet hot stream in condenser)

       Dh is the distillate enthalpy

       D is the distillate flow

       R is the reflux flow

• Reflux ratio is:

       R = Rr * D

                where:

      Rr is the reflux ratio, specified by user

• Coolant flow is:

      C =Qcond / (Coh - Cih)

                where:

      C is the coolant flow

      Coh is the coolant outlet enthalpy

      Cih is the coolant inlet enthalpy

• Minimum heat duty required for reboiler (in case that the heat loss is zero) is calculated as:

       Qrebmin = D * Dh + B * Bh + Qcond - Sum (Fi * Fhi )

                where:

       Qrebmin is the minimum heat duty required forreboiler

       Dh is the distillate enthalpy

       B is the bottom product stream flow

       Bh is the bottom product stream enthalpy

       Fi is the feed stream flow

       Fhi is the feed stream enthalpy

• Real heat duty for reboiler is:

       Qreb = Qrebmin * (1+HL)

                where:

       Qreb is the real heat duty for reboiler

       HL is the heat loss fraction in the column

• Steam flow required is:

        S = Qreb / (Sih - Soh)

                where:

       S is the steam flow required

       Sih is the stem inlet enthalpy

       Soh is the steam outlet enthalpy

• The necessary of steam per 100 mass units of feed is calculated as:

       SPF = 100 * S / F

                where:

       SPF is the steam per feed

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Warnings

Coolant outlet temperature higher than the hot stream temperature in condenser!

Coolant inlet temperature higher than the distillate temperature!

Specified coolant outlet temperature lower or equal than the coolant inlet temperature!

Coolant outlet temperature higher than the distillate temperature!

Steam inlet temperature lower than the bottom product temperature!

Condensate outlet temperature higher or equal than inlet steam temperature!

Condensate outlet temperature higher than the condensing temperature. Steam in condensate!

Condensate outlet temperature lower than the bottom temperature!

Condensate outlet temperature higher than the inlet steam temperature!

Pressure drop in reboiler higher than the inlet steam pressure!

* The Total_Column_Height exceeds the maximum recommended safety height of 175 ft. Rare values are up to 190...212 ft).

* The Fair's Flooding Factor is outside the original correlation limits because : FLV Sherwood No < 0. Impossible situation.

* The Fair's Flooding Factor is outside the original correlation limits because: FLV Sherwood No < 0.01. Extrapolation will be used.

* The Fair's Flooding Factor is outside the original correlation's limits because: Tray_Spacing is outside the range [6..36] in. Extrapolation will be used.

* The Smith's Flooding Factor is outside the original correlation limits because: FLV Sherwood No < 0. Impossible situation.

* The Smith's Flooding Factor is outside the original correlation's limits because: FLV Sherwood No < 0.02. Extrapolation will be used.

* The Smith's Flooding Factor is outside the original correlation's limits because: FLV Sherwood No > 1. Extrapolation will be used.

The Smith's Flooding Factor is outside the original correlation's limits because: The Settling_Height (Tray_Spacing - hw - how) is outside [2..30] in. Extrapolation will be used.

* Froth_Relative_Density abscisa: (uA*(RhoV^0.5)) is out of the range [0..2.5]. Extrapolation will be used.

* The calculated Froth_Relative_Density is outside of the range [0..1].

* Aeration_Factor abscisa: (uA*(Rhov^0.5))is out of range [0..2.5].Extrapolation will be used.

* Aeration_Factor is out of range [0..1].

* The Weir_Constriction_Correction_Factor FW (Bolles) is outside the recomended range limits because: Weir_Length-to-Column_Cross_Section_Diameter ratio (Lw/Dc) < 0.5. Extrapolation will be used.

* The Weir_Constriction_Correction_Factor FW (Bolles) is outside the recomended range limits because: Weir_Length-to-Column_Cross_Section_Diameter ratio (Lw/Dc) > 1. Impossible case. Value is set to zero.

* The Weir_Constriction_Correction_Factor FW (Bolles) exceeds the recomended limit. Extrapolation will be used.

* The FAIR's_Fractional_Entrainment Correlation is outside the recomended range limits because: Flood_Percent < 30%. Extrapolation will be used.

* Flood_Percent > 100%. Flodding regime. Vapor velocity exceeds the estimated flodding velocity. Extrapolation will be used to evaluate the weeping effect.

* Negative pressure drop through tne perforations. Value is set to zero.

The abscisa: Weir_Height + Liquid_Height_Over_the_Weir exceeds the experimental chart range of 4 in. Extrapolated values will be used.

* The Fractional_Hole_Area Af=Ah/Aa is below the experimental chart correlation. Extrapolated values will be used to evaluate the weeping effect.

* The Fractional_Hole_Area Af=Ah/Aa is above the experimental chart correlation. Extrapolated values will be used to evaluate the weeping effect.

* The Chan and Price Dump_Factor is outside the original correlation's limits due to:FLV Sherwood No < 0. Impossible situation.

* The Chan and Price Dump_Factor is outside the original correlation's limits due to: FLV Sherwood No < 0.001. Extrapolation will be used.

* The Chan and Price Dump_Factor is outside the original correlation's limits due to: FLV Sherwood No > 10. Extrapolation will be used.

* The Chan and Price Dump_Factor is outside the original correlation's limits due to: Weir_Hegiht < 1/8 = 0.125 in. Extrapolation will be used.

* The Chan and Price Dump_Factor is outside the original correlation's limits due to: Weir_Height > 5 in. Extrapolation will be used.

* Tray_Spacing is below 24 in. There is inadequate space for manway access on the tray.

* Open(Hole)_Area_Fraction is ouside the recommended range [0.04..0.16]. For Sieve Trays the recommended range is [0.05..0.15], commonly 0.1.

* The Downcomer_Clearence(Seal) should never be under 1/2 in (12.7 mm). Usual Values are {1.5, 1.75, 2, 2.25, 2.5} inches.

* Tray_Deck_Thikness/Hole_Diameter ratio for sieve tray is outside of the recommended range [0.4..0.7].

* The Hole_Pitch/Hole_Diameter ratio for sieve trays is outside the recommended range [2..4.5], with optimum around 3.8 in.

* The Weir_Height should be less than (0.15*Tray_Spacing).The Weir_Height range is [1..4] in and 2..3 in are commonly used.

* The Weir_Height is recommended to exceed the Downcomer_Clearence with at least 1/2 in (12.7 mm). The Weir_Height range is [1..4] in and 2..3 in are commonly used.

* The Top-to-Bottom Sloped_Downcomer_Area ratio is outside the recommended range [1.5..2].

* The abscisa (Liquid_Density-Vapor_Density) is outside the Nutter and Koch correlation chart range [10..75] lbs/ft3.

* Downcomer_Area smaller than (0.05..0.08)*Tower_Cross_Section_Area should be avoided. The recommended range is [0.1...0.2]*Tower_Cross_Section_Area.

* Sloped_Downcomers are not used below 16 in (0.4064 mt) Tray_Spacing. Straight downcomer is recommended to be used.

* The Flow_Path_Length is less then the design limit of 16 in (406.4 mm).It should exceed 16...18 in. There is inadequate space for manway access on the tray.

* The Flow_Path_Length should not exceed (0.64*Column_Diameter) in (good practice guideline).

* The Top_Weir_Length should not be lower than 55% of the Column_Diameter. Tray efficiency might be affected.

* The Top Weir Length-to-Column_Internal_Diameter percent is recommended to be arround 75%, as a common practice.

* The total Top downcomer outlet Weir_Load QL is outside the good practice guideline range [7..13] gpm/in_outlet_weir. Some authors recommend QL values below 8 for sieve trays.

* The total Bottom downcomer outlet Weir_Load QL is outside the good practice guideline range [7..13] gpm/in_outlet_weir.

* The Flow_Path_Length Center-to-Side is less then the design limit of 16 in (406.4 mm). It should exceed 16...18 in. There is inadequate space for manway access on the tray.

* The Flow_Path_Length Center-to-Side should not exceed (0.64*Column_Diameter)(good engineering guideline).

* The Side Top_Weir_Length should not be lower than 55% of the Column_Diameter . Tray efficiency might be affected.

* The Center Top_Weir_Length should not be lower than 55% of the Column_Diameter. Tray efficiency might be affected.

* The Side Top downcomer outlet Weir_Load QL is outside the good practice guideline range [7..13] gpm/in_outlet_weir.

* Total_Tray_Pressure_Drop is ouside the good practice recommendation [3..5] in of liqid; [0.08..0.12] psi.

* Downcomer_Seal might fail. The Clear_Liquid_Height in the Downcomer does not exceed the Downcomer_clearence with at least than 2 inches.

* The Froth_in_Downcomer exceeds the safety limit and may reach the upper tray.

* Risk of choke in the downcomer: Downcomer percent of Choke (Koch correlation) > 90%.

* The Apparent_Residende_Time is lower than the Minimum_Recommended_Residence Time = 3 s.

* The Apparent_Residende_Time is lower than the Minimum_Recommended_Residence Time = 4 s.

* The Apparent_Residende_Time is lower than the Minimum_Recommended_Residence Time = 5 s.

* The FLOOD_Fair percent is below the recommended range [30..80]%.

* Possible Entrainment_(Jet)_Flooding: FLOOD_Fair Correlation > 80%.

* The FLOOD_Percent Kister & Haas Correlation is below the recommended range [30..80]%.

* Possible Entrainment_(Jet)_Flooding: FLOOD_Kister & Haas Correlation > 80%.

* The FLOOD_Smith percent is below the recommended range [30..80]%.

* Possible Entrainment_(Jet)_Flooding: FLOOD_Smith Correlation > 80%.

* Weeping might occur. Weep_Point_Vapor_Load_Percent < 100 %.

* Dumping_Point is reached. Dump_Percent < 100%. All the liquid is weeping through the tray.

* Weeping is significant. The Weep_Fraction > 0.1, the maximum tolerable value.

* The Weir_Height is outside the recommended limits [2...4] in or [(2 - how - 0.5 * hhg), (42 - how - 0.5 * hhg)].

* The Column_Heigt-to-Diameter ratio is outside the optimum range of [20..30].

Errors

Missing utilities stream(s)!

apiMAX full license required!

Calculations cannot be performed!

No feed connected!

No distillate or bottom stream connected!

Empty feed flow!

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