Module4Tnew13讲解.ppt

* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * Traveling grate Fluidized bed incinerator The bed material can be plain sand or limestone (CaCO3), it can remove the acid gases. Lower operational temperature 1450-1750oF (790-950oC) Lower ignition loss Limit particle size Fluidized bed incinerator Fluidized bed incinerator for combustion of wastewater sludge,RDF and wood waste Review Combustion 1.General Advantages: (1)Reduce the volume (85-95% reduction) and weight of wastes. (2)Recover energy Disadvantages: air pollution factors influence on combustion(3T) 2. Description of Combustion Process Review Types of Combustion Systems Mass-Fired combustion systems (Mechanical-grate incinerator) RDF-Fired combustion systems Fluidized bed incinerator Rotary kiln incinerator Pyrolysis 4 Definition Destructive Distillation thermo-cracking reaction to convert thermally unstable organic substances to gas, liquid, and solid fractions (stable) under oxygen free environment The pyrolysis systems use an external source of heat to derive the endothermic reaction in an oxygen-free environment. 5 Reaction Products Reaction Example (cellulose) 3C6H10O5 ? 8H2O +C6H8O +2CO + 2CO2 +CH4 +7C Products Gas stream - CO, CO2, H2, CH4, C2H6, C2H4 Tar/oil - acetic acid, acetone, methane, complex oxygenated hydrocarbons Char - pure carbon, other inert material 6 Description of the pyrolysis process In contrast to combustion and gasification processes, which are highly exothermic, the pyrolytic process is highly endothermic, requiring an external heat source. 7 GASIFICATION SYSTEMS Gasification is the partial combustion of solid waste under substoichiometric conditions to generate a combustible gas containing carbon monoxide, hydrogen, and some gaseous saturated hydrocarbons. 8 ENVIRONMENTAL CONTROL SYSTEMS （环境控制系统） Particulates: ESP (Electrostatic Precipitator), fabric filter颗粒物：静电除尘，布袋除尘 NOx: selective catalytic reduction (选择性催化还原脱硝SCR), selective non-catalytic r