Revised as of 23 November 2020ASPEN软件模拟吸收Design Procedure for an Absorption Unit onthe AspenPlus SoftwareAuthor: Brigitte McNamesThis manual presents all steps necessary to design an absorber using the AspenPlussimulation software. The manual also includes useful tips, recommendations, andexplanations throughout the design procedure. The following example will be used:Example 1Problem Statement: Absorption of Acetone in a Packed TowerAcetone is being absorbed by water in a packed tower having a diameter of m at293 K and kPa (1 atm). The inlet air contains mol% acetone and outlet mol% acetone. The total gas inlet flow rate is kmol/h. The pure water inlet flowis kmol/h. (This example is EXAMPLE taken from reference 1).Schematic:Gas Outletxacetone = Pure Water InletF = kmol/hAbsorberT = 293 KP = 1 atmGas Inletxair = xacetone = F = kmol/hLiquid Outletxacetone = Absorber Design Procedure SDSM&T 2/15ProcedureLogon to the AspenPlus system and start a blank simulation. The flowsheet area shouldappear. (Refer to “AspenPlus Setup for a Flow Simulation” if you need help.)Shown above is the Columns subdirectory. Choose the RateFrac block from thesubdirectory by clicking on it. If you click on the down arrow next to the RateFrac block,a set of icons will pop up. These icons represent the same calculation procedure and arefor different schematical purposes only. Choose the block that best represents the processthat you are designing. For our example we will use the RATEFRAC rectangular blockat the top left corner.RateFrac is a rate-based nonequilibrium model for simulating all types of multistagevapor-liquid operations such as absorption, stripping, and distillation. RateFrac simulatesactual tray and packed columns, rather than the idealized representation of equilibriumstages.A column consists of segments (see schematic for a packedcolumn at right). Segments refer to a portion of packing ina packed column or one or more trays in a tray column.RateFrac performs an initialization calculation where allsegments are modeled as equilibrium stages. The resultsfrom the initialization step are used to perform the rate-based nonequilibrium calculations. To learn more aboutRateFrac and its applications refer to the “RateFrac” helppages.Packed segment n-1Packed segment nPacked segment n+1Absorber Design Procedure SDSM&T 3/15First, create a schematic similar to the one above using the RateFrac block. Refer to“AspenPlus Setup for a Flow Simulation” if you need help. Attach the liquid inlet andgas inlet streams to the feed port. Attach the gas outlet to the vapor distillate port and theliquid outlet to the bottoms port. Once the flow sheet is complete, click the “Next”button ( ) and the title screen should appear (see below). Give the example a title andchange the units from English to Metric on the same screen. Click the button.Absorber Design Procedure SDSM&T 4/15The components screen should appear next. Enter in the species used in the example (seeabove). The “Find” button on the bottom of the screen enables you to quickly search forcomponents in the databanks by formula, name, CAS registry number, molecular weight,and normal boiling point. The “Elec Wizard” button can be used to generate electrolytecomponents and reactions for electrolyte applications from components you entered. Acustom component that is not found in the databanks can be created using the “UserDefined” button. The “Reorder” button will simply reorder the components that arealready defined on the selection sheet. When all components have been entered, click the button.On the next screen, choose a Property Method from the list bypressing on the downbutton to the right of thebox. If you need helprefer to “AspenPlus Setupfor a Flow Simulation.”This example will useNRTL. Then click the button.Absorber Design Procedure SDSM&T 5/15Shown at the left is theinput page for the air/acetone inlet gas.Enter all the data fromthe problem statementfor temperature, pressure, flow rate,and composition.Make sure that unitsand definitions correspond to thevalues that you areentering.The input sheet for the gas inlet stream should appear (see above). Enter the values fromthe problem statement. If values are unknown, leave the respective boxes blank. Whenfinished, click the button. The input sheet for the liquid inlet stream should appear.Once again, enter the respective values from the problem statement, and click the button.The input sheet for the absorber block will appear next. A column consists of segmentsthat are used to evaluate mass and heat transfer rates between contacting phases. Asegment refers to a portion of packing in a packed column or a series of trays in a traycolumn. Enter the number of segments. As a rule of thumb, there should be one segmen