# Modeling and Simulation of IGCC Considering Pressure and Flow Distribution of Gasifier
## 4 Results and Analysis  
### Gasifier Simulation  
Model validation of the gasifier has been implemented based on the El Cerrejon coal of the Buggenum IGCC, for which the proximate analysis and ultimate analysis are shown in Table 1. The simulation results of the molar fraction are given in Table 2, and they have been compared with the reference data [10; 11; 12; 13; 14; 15; 16; 17; 18; 19; 20; 21].  
It can be seen from Table 2 that the results of the V-R model are almost the same as those of the no-pressure model during the steady-state simulation, which means that the V-R characteristics only influence the dynamic response. The above simulation results show that all three models can  
\begin{table}
\begin{tabular}{c c c c c c c c c c} \hline  & \multicolumn{3}{c}{**Proximate Analysis**} & \multicolumn{6}{c}{**Ultimate Analysis**} \\ \hline Moisture & Ash & Volatatiles & Fixed Carbon & C & H & N & S & CI & O \\
1\% & 7\% & 34\% & 59\% & 75.07\% & 4.49\% & 0.96\% & 0.42\% & 0.01\% & 12.05\% \\ \hline \end{tabular}
\end{table}
Table 1: Proximate analysis and ultimate analysis of coal (dry basis).  
Figure 5: Diagram of data flow direction of the IGCC system.  
predict the gasification process in steady state well. However, with the V-R model, more performance parameters can be calculated. The pressure distribution performance along the axial direction is indicated in Figure 6.  
From the result of the pressure drop, it can be observed that the pressure distribution is not linear. The reason is that the heterogeneous reactions, which increase the flow rate, mainly exist in the first few compartments. Thus, the higher flow rate increases the pressure drop in the following compartments. On the other hand, the pressure drop becomes steady in the last few compartments, showing that only homogeneous reactions occur at this part.  
In this paper, we focus on pressure and flow distribution and its influence on the dynamic performance of the gasifier. The dynamic response when the feedstock undergoes a step change is chosen as the research object. The simulation result is also compared with the no-pressure model in the following text.  
The dynamic responses of the pressure of compartments #1 and #10 are shown in Figure 7, with respect to a +1% step change in the oxygen flow rate at the 10 th second.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Syngas at Outlet/Molar Fraction** & **CO** & **H\({}_{2}\)** & **CO\({}_{2}\)** & **H\({}_{2}\)O** \\ \hline lumped model & 65.3\% & 29.4\% & 0.25\% & 0.42\% \\ No-Pressure model & 66\% & 28.4\% & 0.93\% & 1.25\% \\ V-R model & 65.7\% & 28.6\% & 0.94\% & 1.31\% \\ Experimental result & 63.1\% & 30\% & 0.8\% & 1.5\% \\ \hline \hline \end{tabular}
\end{table}
Table 2: Comparison of steady state results for syngas (El Cerrejon Coal).  
Figure 6: Pressure distribution.  
Figure 7: Pressure dynamic response.  
It can be seen that the pressure dynamic response of compartment #10 is later than that of compartment #1 due to the flow direction of the syngas. Moreover, the range of the pressure response of compartment #10 is much smaller than that of compartment #1. The reason is the same as the steady-state analysis, which is because there are only homogeneous reactions in compartment #10 which do not cause the pressure to change.  
The outlet flow rate is influenced by both the inlet parameter and pressure distribution with the V-R model. Therefore, the flow rate would continue changing until the pressure is steady, which is shown in Figure 8.  
Different from the result of the no-pressure model, the dynamic response of flow rate is influenced by the pressure distribution in the new V-R model; thus, the response is delayed about 20 s compared to the no-pressure model to reach the stable state. The results from the V-R model can reflect the transportation delay as well as the volume inertia characteristics. This will be the advantage for the new gasifier model.