Page tab

Now we need to install feed and product lines with valves and a pump. Clicking the Pressure Changers page tab produces a display of compressors, pumps, valves, and other components (see Fig. 2.30). Clicking the appropriate icon and inserting the device on the flowsheet produces the flowsheet shown in Figure 2.31 with three valves and one pump. The valves and pump have been renamed. 

Clicking the Kinetics page tab opens the window shown in Figure 2.52. The dropdown arrow on the first line lets you select one of the three reactions. The kinetic parameters for reaction 1 are shown in Figure 2.52. The Reacting Phase is selected as Liquid. The Rate basis is selected as React (vol). The concentration fCi] Basis is selected as... 

Click on the reactor block and then on Setup. The window shown in Figure 2.55 opens on which the operating temperature and pressure are set, as well as the reactor volume and the valid phases (Liquid-Only). Instead of setting temperature, other options could be selected such as reactor heat transfer rate. Selecting the Reactions page tab under Setup opens the... 

To convert a steady-state simulation into a dynamic simulation, the Dynamic button on the top toolbar shown at the top of Figure 3.56 is clicked. If this button is not showing, go to the top toolbar and click View and Toolbars. The window shown at the bottom of Figure 3.56 opens, on which the box in front of Dynamic is clicked. Then the Dynamic item under the reactor block R1 is clicked, which opens the window shown in Figure 3.57. The Heat Transfer page tab lists six possible options that can be used in the dynamic simulation. In our discussion of these alternatives, we will consider the... 

Figure 3.58 shows the window when Constant temperature is selected on the Heat Transfer page tab. We specify a Medium temperature of 400 K. With the reactor at 430 K, this gives a 30 K differential driving force. 

Click the Closed loop ATV bullet, start the simulation mnning, and click the Start test button. After several cycles, click the Pause button to stop the simulation and click the Finish test button at the bottom of the Tune window (see Fig. 3.79). The ultimate gain (3.73) and the ultimate period (4.8 min) are displayed, as shown in the left side of Figure 3.80. To calculate the controller tuning constants, click the Tuning parameters page tab on the Tune window and select either Ziegler-Nichols or Tyreus-Luyben. 

Now we are ready to set up the reactor. Figure 4.26 shows the Setup window for the reactor block with the Specifications page tab open. There are several alternative... 

In Figure 4.26 a temperature profile has been specified. The reactor starts at 300 K at time equal zero, and the temperature is ramped to 400 K at 10 min. Then it is ramped to 430 K at 20 min and remains at this temperature for the rest of the 120-min batch. Figure 4.27 shows that the Reactions page tab permits the installation of reactions in the normal way, as discussed in Chapter 2. The primary reaction is ethylene and benzene forming ethylbenzene. 

The Stop Criteria page tab opens the window shown in Figure 4.28, on which one or more criteria for ending the batch cycle can be specified. We select a Time variable and set the Stop value to 7200 s (2 h). Other criteria could also be specified, such as a maximum reactor temperature and a desired concentration. 

Figure 4.29 shows the Operating Times page tab. The Batch feed time bullet is clicked and specified to be 1 h. This means that the 50 kmol/h specified for the FE feedstream is on an hourly basis. To help clarify this none-too-intuitive aspect of the feedstream, if a value of 2 h is specified for the Batch feed time, the flowrate of the FE stream will be set at 50 kmol/2 h. Several other straightforward parameters are also set on this page tab. Figure 4.30 shows the Continuous Feeds page tab, on which a fiow-versus-time profile can be specified. 

The tubular reactor in Aspen Plus is called RPLUG and is installed on the flowsheet as shown in Figure 5.21. Two different tubular reactors with their feed and product streams are shown. The five possible types of reactors are listed on the Specifications page tab when Setup under the reactor block is clicked. 

This type is selected in the top window shown in Figure 5.25 on the Specifications page tab. The overall heat transfer coefficient (U = 142 W K-1 m 2) and the coolant temperature (400 K) are specified. Clicking the Configuration page tab opens the window shown at the bottom of Figure 5.25. The number of tubes (250), their length (10 m), and their diameter (0.1 m) are specified. 

Figure 5.28 shows the flowsheet and the Specifications page tab for a cooled tubular reactor with co-current flow of coolant. The flowrate and temperature of the coolant... 

Figure 6.34 shows the Aspen Plus flowsheet with these two adiabatic reactors installed. The empty reactor is 10 m in length. The catalyst-filled reactor is 20 m in length. The reactor effluents for the two cases are identical. Control valves are installed on the gas feedline and the gas reactor effluent line. Figure 6.35 shows the Catalyst page tab window under Setup for the reactor with catalyst. The catalyst properties are specified. 

Figure 6.78 shows how the LHHW kinetics are selected. Figure 6.79 gives the Input window for the reactions R-l with the Stoichiometry page tab selected. Figure 6.80... 

Then a temporary heater was installed to heat the inlet stream to the first reactor to 265°C. The reactor is specified to have a constant coolant temperature (Fig. 6.86) of 260°C and a heat transfer coefficient of 244 kcal h-1 m-2 °C 1. Figure 6.87 gives the Configuration page tab with the physical dimensions of the tubes. Figure 6.88 shows the catalyst loading. 

Figure 1-11. The Page Setup dialog box showing the Page tab.

If the Print Area you selected requires more than one page, you can choose Page Setup and change the value in the Reduce/Enlarge box to less than 100%. Sheets printed with values less than about 60% are difficult to read, though. To obtain the appropriate reduction value automatically, after you ve selected the area to be printed, choose the Page tab and press the Fit To 1 Pages Wide By 1 Tall button. 

Clicking the Columns page tab and clicking the arrow just to the right of RadFrac opens the window shown in Figure 3.3, which contains several types of columns full columns, strippers (with a reboiler but no condenser), rectifiers (with a condenser but no reboiler, absorbers (with neither) and so on. Click the full column button on the top row, second from the left, and move the cursor to the blank flowsheet. The cursor becomes a cross. If we click on the flowsheet, a column icon appears, as shown in Figure 3.4. 

Now click the Streams page tab. A window opens on which the location of the feed tray must be given. For the moment, we set this in the middle of the column on Stage 16 (see Figure 3.28). Later, we will come back to this question and determine the optimum feed tray location by finding the tray that minimizes reboiler heat input. 

The last page tab is Pressure. Clicking it opens the window shown in Figure 3.29 in which we specify the pressure in the reflux drum (condenser) and the pressure drop through each of the trays in the column. As discussed above, we set the reflux drum pressure at 14 atm (be careful to change from N/m ). A reasonable tray pressure drop is about 0.0068 atm per tray (0.1 psi per tray). All the items in the Cl block are now blue, so the column is completely specified. Next, the design parameters of all the valves and pumps must be specified. 

Then, click the second page tab Components. Click the IC4 in the left column under Available components. Clicking the > button moves IC4 over to the right Selected components column (Fig. 3.39b). Click the third page tab Feed/Product Streams, select D1 in the left column and click the > button to move it to the right column. The Design Spec is now completed. Notice that the number 1 in Figure 3.39c is blue. 

The second Design SpecA ary is set up in the same way. Clicking Design Spec opens a window on which you specify a new Design Spec 2 . Then, the mole purity of the bottoms 61 is specified to be 0.01 mol fraction propane. See Figure 3.42 for the three steps on the three-page tabs. 

All the detailed information about the vapor and liquid flows throughout the column can be accessed by clicking the item Report under the Cl block and under Property Options, checking the box in front of Include hydraulic parameters. Then, after the program is run, click the item Profiles and the Hydraulics page tab. The window that opens gives lots of information about liquid and vapor rates and properties, as shown in Figure 3.54. 

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