## 4 Results and Discussion
### Experimental Results and Analysis
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Factors** & & \(w\) **(m)** & \(l\) **(m)** & \(\beta\) (\({}^{\circ}\)) & \(\alpha\) (\({}^{\circ}\)) \\ \hline  & K1 & 1,514,275 & 1,506,447 & 1,510,055 & 1,509,803 \\  & K2 & 1,508,032 & 1,508,205 & 1,506,781 & 1,506,954 \\  & K3 & 1,501,155 & 1,508,810 & 1,506,626 & 1,506,705 \\  & k1 & 504,758.33 & 502,149 & 503,351.67 & 503,267.67 \\  & k2 & 502,677.33 & 502,735 & 502,260.33 & 502,318 \\  & k3 & 500,385 & 502,936.67 & 502,208.67 & 502,235 \\  & R & 4373.33 & 787.67 & 1143 & 1032.67 \\  & Superior level & \(1\) & 3 & 1 & 1 \\  & Order of factors & & \(w>\beta>\alpha>l\) & & \\ \hline  & K1 & 24,926 & 21,620 & 23,460 & 22,683 \\  & K2 & 21,643 & 22,206 & 21,934 & 22,525 \\  & K3 & 20,530 & 23,273 & 21,705 & 21,891 \\  & k1 & 8308.67 & 7206.67 & 7820 & 7561 \\  & k2 & 7214.33 & 7402 & 7311.33 & 7508.33 \\  & k3 & 6843.33 & 7757.67 & 7235 & 7297 \\  & R & 1465.34 & 551 & 585 & 264 \\  & Superior level & 3 & 1 & 3 & 3 \\  & Order of factors & & \(w>\beta>l>\alpha\) & & \\ \hline \hline \end{tabular}
\end{table} 
Table 7: Analysis of experimental results. The flow characteristics of the sinter in the obtained suitable Venturi furnace were studied. To improve the calculation efficiency, the discharge rate of the sinter was appropriately increased. The results are shown in Figure 6. It can be seen that after 90 s of discharge, the flow pattern of the sinter did not change much from that at 80 s. When the discharge of the material was continued for 100 s, the flow pattern of the sinter was still similar to that at 90 s. Therefore, it is believed that the downward movement of the sinter after 90 s of discharge reached a stable state. From Figure 6a, it can be seen that in the vertical section of the Venturi furnace obtained from the orthogonal experiments, the downward movement of particles in the sidewall area was suppressed, and the minimum _MFI_ of particles was only 0.43. This is because the friction force on the particles in the central area of the vertical section was less than that in the sidewall area, making the downward movement of the particles in the central area smoother. After the Venturi structure was used, the width of the cavity for the downward movement of the material became narrow, causing particles in the sidewall area to be squeezed by particles in the central area and making it difficult for them to flow into the mainstream area, resulting in particle accumulation. Therefore, an attempt was made to install a baffle in the central area of the vertical section to increase the friction of the particles in the central area and balance the downward movement of the particles, as shown in Figure 6b. At this point, the downward distances of the particles in the sidewall area and central areas were basically the same. The minimum _MFI_ of the particles in the vertical section was calculated to be 0.71, indicating that the fluidity of the sinter was significantly improved. Figure 5: Influence of structural parameters. (a) \(w\); (b) \(\beta\); (c) \(\alpha\); (d) \(l\). Under the same heat exchange conditions, the sensible heat recovery of the existing furnace type was compared with that of the improved Venturi furnace type, as shown in Figure 7. It can be seen that the improved Venturi furnace type could recover 504,864 ] and reduce the pressure drop to 7053 Pa during the heat transfer time, both of which are higher than the existing furnace type's 493,976 ] and 4088 Pa. Compared with the results of the orthogonal experiment, the sensible heat recovery was second only to scheme 1 in Table 6, but the pressure drop was lower than that of scheme 1. This is because the influence of \(l\) on the pressure drop of the gas was greater than that on the sensible heat recovery. The above results show that the improved Venturi furnace was effective in improving the gas-solid heat transfer and controlling the increase in the gas pressure drop. Figure 6: Comparison of material flow patterns in steady state.