| 摘要 |
This disclosure discloses a process and an anaerobic digestion system for crop stalk/straw. The process in one example comprises (A) Feeding, (B) Heating and Digestion at the set temperature, (C) Discharging of Biogas, Sludge and Effluen{grave over ( )}t. The system in one example comprises (I) High Solid Content Digester (II) Hydro-Circulation Digester and (III) Stalk/Straw Feeder. Steps (A), (B) and (C) are accomplished in the devices (I) and (II). The step (A) is accomplished through the stalk/straw feeder (III), a special feeding mechanism, by which the crushed or smashed stalk/straw is pushed into the bottom of digester vessel. After being fermented or digested in the device (I), feedstock that is the mixture of biomass and water flows freely into the device (II) through the feedstock discharge outlet. The stalk feeder (III) is comprised of a hopper (7), a support (14), a control system and a hydraulic system. The hydraulic system comprises a hydraulic cylinder (3), a hydraulic pump station (1), hydraulic pipelines (2), a piston (15), a piston rod (5) and a feedstock input passage (13). The hopper is square shaped on its upper section and conical shaped at its lower bottom part. The hopper has a high-level sensor and is connected to transporting part driven by the hydraulic system at its lower section. The hydraulic system and the level sensor are wired to the control system to provide feeding function to the digester vessel or pressure vessel. Step (B) is accomplished by checking the temperatures in the digester vessels by the temperature sensors mounted on the devices (I) and (II). When the digester vessel temperature is below the set value, the control system of the digester vessels starts automatically to send the mixture of biomass and liquid through the circulation pump into the heat exchanging mechanism; and the heated flow then goes back to the digester vessels. This step is repeated in the digester (II) to keep the digester vessel at the set temperature while material inside the digester (II) is mechanically agitated simultaneously. With being stirred by a mixer, feedstock in device (I) gets mixed sufficiently with anaerobic organisms. In Step (C) the material inside the digester vessel (33) is digested continuously and converted into biogas, sludge and effluent, which run out through its individual outlet. The device (II) comprises a digester vessel (33), a heat exchanging mechanism (27), a feedstock inlet (21), interior and exterior membranes (34 and 35), a safety valve (36), a feedstock output valve (38), a blower (39), temperature sensors (32), a electric valve (31), a circulation pump (29), a backstop valve (30) and a control system (20). The heat exchanging mechanism is mounted outside the digester vessel. The biogas outlet valve (37) and effluent output valve (38) are arranged on another side of the digester vessel (33). The digester vessel (33) is covered with an interior and an exterior membranes (34 and 35). There is a safety valve (36) installed on the top of exterior membrane (35). Between interior and exterior membranes there is an air pocket, which is connected to the blower and pipelines. The temperature sensor (32) is arranged under the digester vessel (33). The control system mounted outside the digester vessel (33) is wired to the circulation pump (29), electric valve (31), temperature sensor (32) and blower (39). In this disclosure, the hydraulic circulation and PLC control system are applied. The digester vessels are used also as biogas storage tank with simple structure. It is safe to operate with low cost. This disclosure also discloses automatic mechanical stirring and feedstock heating outside the digester vessel as well as hydro-stirring that takes place to form the effect of flow turbulence while the feedstock is pumped into and out of the heat exchanging mechanism. The examples in this disclosure can be utilized in the digestion system for crop stalks/straws, livestock manure and sewage. |
