# A Feasibility Study of Utilizing Nuclear Energy for an Existing MED-TVC Desalination Plant
## 3 Simulation of MED-TVC Desalination Plant  
An existing MED-TVC desalination plant located on the west coast of Saudi Arabia with a water production capacity of 91,200 m\({}^{3}\)/day and ten effects [15], was simulated using Aspen Plus software. Table 1 shows the desalination plant's specific information. Figure 2 depicts the flow sheet of the MED-TVC desalination plant. Medium pressure (MP) steam, which is generated using crude oil as a heat source, enters a steam generator (SG) and exchanges its latent heat with the distillate coming from the first effect to generate motive steam at MP condition. The entrained vapor used for the thermal vapor compression device is extracted from the vapor stream produced in the sixth effect and mixed with the motive steam before it enters the first effect. After successive evaporation occurs in the ten effects, the vapor that comes out of the last effect is sent to a total condenser where it exchanges its heat of condensation with the seawater feed. The produced distillate is then mixed with other distillates generated from other effects, collected, and pumped to the post-treatment facility. The heated seawater feed, after leaving the condenser, is split in a parallel arrangement and preheated between effects before it enters into the effect evaporators. Figure 1: Schematic diagram of the research methodology. An electrolyte model with metric units was selected in Aspen Plus, with the ELECT-NRTL property package, to simulate the seawater desalination plant. Each effect in the desalination plant is modeled in Aspen Plus as a combination of a heat exchanger and a simple flash drum, as shown in Figure 3. The vapor generated from each effect is entered into the tube-side of the heat exchanger and condensed to become a distillate. The resultant heat of condensation or the condenser duty is added as a heat stream to the adjacent flash drum. The feed seawater stream is entered into the flash drum, where the generated vapor from flashing exits from the top of the drum, and the rest of the seawater exits as brine from the bottom. \begin{table}
\begin{tabular}{c c} \hline
**Location** & **West Coast on Red Sea Shores** \\ \hline Capacity & 91,200 m\({}^{3}\)/day \\ \hline Energy source & Crude oil \\ \hline Number of effects & 10 \\ \hline Configuration & Parallel \\ \hline Distillate (kg/h) & 376,8000 \\ \hline Brine (kg/h) & 944,2708 \\ \hline Performance ratio (PR) & 14.62 \\ \hline \end{tabular}
\end{table} 
Table 1: Existing MED-TVC Desalination Plant’s Specific Information. Figure 3: Modules that are used to simulate the MED Effect in Aspen Plus. Figure 2: Schematic diagram of the existing MED-TVC. The following mathematical expressions represent the model shown in Figure 3. The water feed to each effect (\(\rm F_{i}\)) can be calculated from the mass flow rate of the seawater intake (\(\rm M_{f}\)) and the total number of effects (n), as given in Equation (1):  
\[\rm F_{i}=\frac{M_{f}}{n} \tag{1}\]  
The mass balance around the effect is calculated as follows:  
\[\rm F_{i}=V_{i}+(B_{i}-B_{i-1}) \tag{2}\]  
where \(\rm V_{i}\) is the generated vapor from the effect as a result of seawater being flashed and evaporated on the surface of the tube bundle inside the effect. \(\rm B_{i}\) denotes the brine flow rate. The energy balance around the effect is given by Equation (3):  
\[\rm V_{i-1}Lv_{i-1}=F_{i}C_{pf}(T_{i}-T_{f})+V_{i}Lv_{i} \tag{3}\]  
where (Lv) is the latent heat of vaporization inside the effect, and (\(\rm C_{pf}\)) is the heat capacity of the seawater. The salt balance around the effect can be calculated by Equation (4):  
\[\rm F_{i}X_{fi}=B_{i}X_{Bi} \tag{4}\]  
where \(\rm X_{fi}\) and \(\rm X_{Bi}\) are the concentration of salt in seawater and brine, respectively.