Liquid simulation outputs

To complete the construction of the Y-X diagram from simulation results, the feed line must be drawn. The intersection with the diagonal of a straight line drawn through the feed composition determines one point on the q-line. One other point is determined by the feed equilibrium vapor and liquid compositions at the feed tray conditions. If the feed is a saturated liquid, the equilibrium liquid composition is the same as the feed composition, and the equilibrium vapor composition is the bubble point composition on the equilibrium curve. In this case the q-line is vertical. For a saturated vapor feed, the equilibrium vapor composition is the same as the feed composition, the equilibrium liquid composition is the dew point composition, and the q-line is horizontal. For a mixed-phase feed, the c/ line slope is determined by the feed thermal condition (Section 5.2.2). Note that, for a multi-component mixture, the feed equilibrium vapor and liquid compositions from the simulation output may not lie exactly on the equilibrium curve because of the discrepancies resulting from lumping the light components in one pseudocomponent. 

The first data-file version is a system of seven components Zn-K-Fe-He-0-Cl-H. It contains the gas phase, the liquid salt phase, which is composed of four constituents KCl, ZnCl2, FeCl2, FeCl3, and several condensed phases (oxides, chlorides, etc.) and the metal phase (Fe). As the interaction between the salt and the metal is very dependent on the interaction between the salt and the gas, it was reasonable to devise a model that could calculate the whole system. The first simulation output for the case described in Figs 29.5 and 29.6 is presented in Figs 29.8, 29.9 and 29.10. The main components in the salt are KCl (initial value 50 mol.%) and ZnCl2 (initial value 50 mol.%). The simulation conditions, explained in detail in [12], are ... 

The module FLASH simulates the reformer flash separator by using a modified Chao-Seader method. The necessary constants for the Chao-Seader correlation have been developed for the lumped components. The output from this module determines the liquid yield and the composition of recycle gas. 

Here is our MATLAB routine absorbtoweriterXe.m that finds the output liquid concentration Xe for the simulation problem (a) according to Figure 6.23. 

WARNING There is no valve immediately downstream o( the liquid outlet stream. A liquid level control will not be added automatically as Its output can not be connected You should check whether a level controller is needed for a stable dynamic simulation. 

Table 1 gives the components present in the crude DDSO and their properties critical pressure (Pc), critical temperature (Tc), critical volume (Vc) and acentric factor (co). These properties were obtained from hypothetical components (a tool of the commercial simulator HYSYS) that are created through the UNIFAC group contribution. The developed DISMOL simulator requires these properties (mean free path enthalpy of vaporization mass diffusivity vapor pressure liquid density heat capacity thermal conductivity viscosity and equipment, process, and system characteristics that are simulation inputs) in calculating other properties of the system, such as evaporation rate, temperature and concentration profiles, residence time, stream compositions, and flow rates (output from the simulation). Furthermore, film thickness and liquid velocity profile on the evaporator are also calculated. 

In order to understand the differences between the results of the different models, the authors also calculated the interaction energies between water and the ions of the ionic liquid. The results are reproduced in Table 3. The table shows at first that the variation in the interaction energies for the different computational approaches is small. This demonstrates that even small inaccuracies can have significant effects on the output of a simulation. Moreover, the table shows also that the TIP5P model... 

The curves show the output concentration of CA in the sweeping stream of inert liquid as a function of clock time during temperature ramping. The shape of the curves is typical ofTPD signals. The curve on the left represents desorption in a TS-CST-SSR with zero void volume Vv so that VfVv = oo. The next line shows desorption for the system at the same run conditions in a reactor with V/Vv = 0.1. The remaining curve repeats the simulation for VfVv = 0.01. One can readily envision several desorption peaks combining to give a TPD spectrum. 

Fig. 5. Output power characteristics of a liquid-junction solar cell with n-CuInSe2 photoanode and KI-KI3-CUI-HI electrolyte under 100 mW/cm solar simulated irradiation [7].

The I structure in liquid water cannot be inferred from the experimental methods listed in Table 2.1 because those methods provide data that are time averages over many I structure configurations. However, the technique of molecular dynamics (MD) computer simulation has led to reliable information about the I structure. In this technique, a computer is used to solve the classical mechanical equations of motion with a chosen intermolecular potential function for a few hundred water molecules constrained in space to maintaining the equilibrium liquid density, with data on the instantaneous position and velocity of the molecules provided both as numerical output and in the form of stereoscopic pictures. The principal features of the I structure determined in this fashion are ... 

This chapter presents brief descriptions and some theoretical background of the most widely used pumps for liquids, and compressors and expanders for gases, all of which are modeled in simulators. Heuristics for the application of these devices during the synthesis of a chemical process are presented in Chapter 5. Further information on their selection and capital cost estimation is covered in Chapter 16. More comprehensive coverage of the many types of pumps, compressors, and expanders available is presented in Sandler and Luckiewicz (1987) and in Perry s Chemical Engineers Handbook (1997). After studying this chapter and the materials on pumps, compressors, and turbines on the multimedia CD-ROM that accompanies this book, the reader should be able to explain how the more common types of pumps, compressors, and expanders work and how a simulator computes their power input or output... 

Figure 18.7 gives results for a 30% increase in the setpoint of the feed flow controller at 0.5 h. The flow controller output signal (OP FC) increases. The integral time of the feed flow controller in this simulation is 5 min. The level increases, which opens the liquid... 

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