Gas distribution between main gas inlet and three auxiliary inlets at 0.25 m, 0.5 m and 0.75 m was also simulated to study
possible improvement in heat recovery. Making use of results of previous sections, gas distribution ratios between the four inlets were varied in the range of 1:1:1:7 to 1:1:7:1. Results are shown in Fig. 6 and it is evident that the optimum gas distribution ratio is 1:1:1:7. Maximum solid temperature obtained with optimum four gas inlet system is 2 °C greater than that achieved with three gas inlet system. For a gas to solid mass flow ratio of 5, the optimum gas distribution ratio is found to be 1:1:0.5:2.5, which gives a solid temperature at 1 m, around 1 °C greater than that achieved with three inlet system, as evident from Fig. 7. Changes in gas distribution affect the final solid temperature very little for a gas to solid mass flow ratio of 5, since the various ratios simulated are not much different.