TECHNOLOGY FOCUS - CHEMICAL ENGINEERING - Preferred Method: Processing the agricultural waste into combustible gas comprises(A) drying the agricultural waste and crushing into 1-2 cm long;(B) adding silica material as catalyst to crushed material in a ratio of 0.005:1;(C) introducing the mixture to a biogasification furnace to react at 800?oC, where heat dissipation and carbonization of the mixture can be carried out naturally after absorbing heat and combustible gases, e.g. carbon monoxide (CO), hydrogen (H2) and methane (CH4) can be generated in the carbonization process;(D) introducing the combustible gases to a desulfurizer through a blower; and(E) introducing desulfurized gases to a gas container.Processing plastic garbage into combustible gas comprises(A) removing surface moisture of waste plastic by laundry dryer and then completely removing moisture in plastic by a dryer;(B) placing dried plastic in an extruder and introducing to a mixing tank at 250-300?oC to melt the plastic and carry out thermal decomposition;(C) neutralizing hydrogen chloride (HCl) gas generated by thermal decomposition by absorbing in spray tower through a suction fan and then adsorbing by active carbon for removing chlorine gas and simultaneously controlling harmful gas dioxin generated in the next step;(D) introducing a small quantity of dioxin through the spray tower, adding a strong base catalyst to spray solution to oxidize and decompose dioxin and generate harmless steam, carbon dioxide and chloric acid gas;(E) introducing the melted plastic into a thermal decomposition tank at 380-450?oC, where generated gases are collected and then oxidized by the catalyst in washing tower and thermal decomposition gas without harmful components is further cracked by contacting with the catalyst in a catalytic cracking tower; and(F) converting the cracked gas after condensation and fractionation to combustible gas and industrial oil, where the combustible gas is stored and the combustible gas comprises 1-4C hydrocarbon and industrial oil comprises 5-12C light oil and 12-18C heavy oil.