NOVELTY - Fermentation device comprises fermentation reactor, liquid supply pipeline, heating device, stirring device, temperature measuring device, humidity measuring device, and bracket. The fermentation reactor comprises upper layer fermentation reactor and lower layer fermentation reactor. It has cuboid boxtype structure and is fixed to bracket. The upper layer fermentation reactor and lower layer fermentation reactor are identical in structure and size.    USE - Fermentation device used for biomass fermentation reaction (claimed).    ADVANTAGE - The fermentation device has low energy consumption, low cost, easy to operate, safe, and reliable. It allows fully stirring of material to achieve aerobic reaction. It improves processing capability for materials using double-layer reactor design. It improves fermentation efficiency of materials.    DETAILED DESCRIPTION - Fermentation device comprises fermentation reactor, liquid supply pipeline, heating device, stirring device, temperature measuring device, humidity measuring device, and bracket. The fermentation reactor comprises upper layer fermentation reactor and lower layer fermentation reactor. It has cuboid boxtype structure and is fixed to bracket. The upper layer fermentation reactor and lower layer fermentation reactor are identical in structure and size. The front and back walls of fermentation reactor form interlayer structure. The fermentation reactor is provided with material inlet and material outlet, inlet of liquid supply pipe, inlet and outlet of heating pipe, outlet of heating pipe, and exhaust fan. The exhaust fan is embedded on cover of reactor. The liquid supply pipeline is provided with valve for respectively controlling addition of bacterial liquid and water by identical pipeline. The outlet of liquid supply pipeline after entering into fermentation reactor is provided with atomizing nozzle. The heating device is solar water heater. The two heat exchangers of solar water heater are located in interlayer between front and back walls of upper layer fermentation reactor and lower layer fermentation reactor, and are connected with inlet of heating pipeline and outlet heating pipeline of fermentation reactor by pipeline. The stirring device comprises motor, transmission belt, and two spiral stirrers. The motor is fixed to bracket. The two spiral stirrers are identical in structure. The spiral stirring blades of each spiral stirrer are symmetrically distributed in opposite direction by regarding center of rotating shaft as boundary. The rotating shafts of two spiral stirrers are fixed in two fermentation reactors by bearing bases in centers of lateral plates on two sides of fermentation reactor, respectively. The motor is connected with belt wheels of two spiral stirrers by transmission belt. The two groups of temperature measuring device sensor probes and two groups of humidity measuring device sensor probes are located in two fermentation reactors and are connected with temperature measuring instrument and humidity measuring instrument of control chamber by lead wire. An INDEPENDENT CLAIM is included for application of fermentation device in performing biomass fermentation reaction by adding crushed biomass in upper layer fermentation reactor; starting stirrer and exhaust fan; adding bacterial liquid and water in upper layer fermentation reactor by liquid supply pipeline while stirring; sequentially stirring for 3-8 minutes, in which aperture of spray head of liquid supply pipeline when adding bacterial liquid is 3 mm and aperture of spray head of liquid supply pipeline when adding water is 1 mm; closing stirrer and exhaust fan; displaying temperature and humidity of material by thermo detector and moisture meter; supplying heat to upper layer fermentation reactor by solar heater to keep temperature at 40-50 degrees C; supplying water by liquid supply pipeline and keeping humidity at 35-55%; stirring for 12 hours by stirring; holding stirring for 15 minutes including 10 minutes of positive stirring and 5 minutes of inverted stirring at 5-18 revolutions per minute; starting exhaust fan until finishing stirring; fermenting for 3-6 days; completely putting rotten plastic in upper layer fermentation reactor; closing material outlet of upper layer fermentation reactor; putting raw materials in upper layer fermentation reactor again; repeating fermentation reaction; putting materials in lower layer fermentation reactor when fermentation reaction process is completed in upper layer fermentation reactor; performing fermentation for 2-4 days in lower layer fermentation reactor; and discharging final fermentation product.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic view of fermentation device.