Experimental studies have been performed to observe the basic phenomena of $1^st$ combustion chamber in MWC. To do this reduced scale apparatus was made and this can simulate the 2-D steady behavior of real plant(direction of the grate and direction of the waste depth) as 1-D(direction of the waste depth) unsteady behavior. Wood was used for waste. LHV of waste, waste particle size and flow rate of combustion air was taken as important parameter of this experiment. Temperature of gas and particle of waste and concentration of $O_2$, CO and $CO_2$ was measured as back data for analysis. For the quantitative analysis, three notation, that is, combustion proceeding rate, total combustion time and time particle combustion time was defined.
As the LHV of waste increase, combustion proceeding rate was increased and in the case of low-quality waste flame couldn't propagated into bottom of bed. As the particle size increase, combustion proceeding rate was decreased and the particle combustion time - this means the time necessary for complete combustion of char - was linearly increased. As the rate of combustion air, until it reaches some critical point combustion proceeding rate was increased. But in the case when too much air was injected, combustion proceeding rate decreased. So in MWC, appropriate selection of combustion air is very important.