## 6 Results and Discussion  
### Sequential Optimization  
Sequential optimization involves optimizing the operating conditions of the SOFC-GT system first and then achieving SRC-KC-ORC power generation. The methods adopted for the SOFC system, SRC, KC, and ORC are REFPROP and the Peng-Robinson equation [30]. In the SOFC-GT system, streams 1-2, ammonia from tank 3, 16-17, 22-23 and 34-35 in E-100, E-101, E-102, E-103, E-104, E-105, and E-106 were selected to perform heat integration. The enthalpy values of the inlet and outlet streams were used to compute the heat load of the component. However, for the component stack of the SOFC system, the difference between the inlet and outlet enthalpies of the component is calculated as the sum of the electric power and heat released. Because the heat load of the component stack is small, the component stack is assumed to be ideal for simplifying the calculation, which only produces electricity without heat loss. The power calculations are shown in Equations (21)-(35), respectively: For an SOFC system that does not require thermal utilities, the process parameters of the SOFC system are optimized to maximize the stack power, as shown in Table 7.  
The SRC-KC-ORC was optimized under the optimal operating conditions of the SOFC system. During optimization, the hot/cold identity of streams 1-2 and ammonia from tank 3 in E-100 and E-101 were identified based on the heat load. In this sense, the corresponding constraints were calculated using ASPEN HYSYS V12.1. The temperature difference of the pinch points was assumed to be 5 \({}^{\circ}\)C. Meanwhile, the optimal solution can be obtained in a few loop iterations using a genetic algorithm. At this point, the SRC, KC, and ORC power generation reaches a stable level, and the optimal parameters are listed in Table 8. The detail operational specification of each node is presented on Table 9. \begin{table}
\begin{tabular}{c c} \hline \hline
**Parameter** & **Value** \\ \hline E-100 inlet temperature (\({}^{\circ}\)C) & 203.4 \\ E-100 outlet temperature (\({}^{\circ}\)C) & 492.6 \\ E-101 inlet temperature (\({}^{\circ}\)C) & 29.85 \\ E-101 outlet temperature (\({}^{\circ}\)C) & 492.6 \\ Stack temperature (\({}^{\circ}\)C) & 878.1 \\ Afterburner temperature (\({}^{\circ}\)C) & 1193 \\ \hline \hline \end{tabular}
\end{table} 
Table 7: Detailed operating conditions of the SOFC system under the conditions of maximum power. \begin{table}
\begin{tabular}{l c} \hline \hline
**Parameter** & **Value** \\ \hline SRC evaporating temperature (\({}^{\circ}\)C) & 360.9 \\ \hline SRC evaporating pressure (kPa) & 19,000 \\ \hline SRC power (kW) & 175.8 \\ \hline KC evaporating temperature (\({}^{\circ}\)C) & 175 \\ \hline KC evaporating pressure (kPa) & 6493 \\ \hline KC power output (kW) & 24.37 \\ \hline ORC evaporating temperature (\({}^{\circ}\)C) & 223 \\ \hline \hline \end{tabular}
\end{table} 
Table 8: Simulation results for SRC, RC and ORC. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Parameter** & **Value** \\ \hline ORC evaporating pressure (kPa) & 12,500 \\ \hline ORC power output (kW) & 71.23 \\ \hline Stack power (kW) & 3800 \\ \hline Gas turbine power (kW) & 1114 \\ \hline Total power output (kW) & 5185.46 \\ \hline \end{tabular}
\end{table} 
Table 8: _Cont._  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Node** & **Temperature** & **Pressure** & **Molar Flow** & **Mass Flow** & \ \begin{tabular}{c} **Liquid** \\ **Volume Flow** \\ \end{tabular}  \\ \hline Unit & C & kPa & kgmole/h & kg/h & m\({}^{3}\)/h \\ \hline Air in & 29.85 & 101.30 & 213.38 & 6156.00 & 7.12 \\ \hline \begin{tabular}{c} Ammonia \\ from tank \\ \end{tabular}