Technology and equipment for preparation of synthetic gas by two-stage high temperature biomass gasification

[0019] The present invention will be further described below in conjunction with the drawings.

[0020] The present invention provides a two-stage high-temperature biomass gasification process for preparing synthesis gas. The method includes the following steps:

[0021] The biomass raw materials such as rice husk, straw, wood chips, etc. are crushed into powder, and two storage bins I and II connected in series are used for feeding to realize continuous feeding while ensuring system sealing. A valve is arranged between the two sealed storage bins; the storage bin is connected with the air compressor 1 through a pipeline to provide balance gas. Then the raw materials are fed into the gasification furnace I through the screw feeder 2 for the primary gasification reaction, and the feed rate is controlled and adjusted by the rotation speed of the screw feeder 2;

[0022] The gasification reaction is carried out in two stages. The raw materials first enter the furnace through the feed port located in the lower part of the gasification furnace I, and participate in the initial gasification reaction at a temperature of 700~800℃. The gasification medium is provided by the air compressor 1. Compressed air enters from the bottom of the furnace, the airflow direction is from bottom to top, and the gas flow is measured by a flow meter on the pipeline; biomass gas, unreacted solids and tar (gas at high temperature) and other gas-solid mixtures produced by the initial gasification At high temperature, the gas-solid mixture exits directly into the gasifier II from the top. The gas-solid mixture enters the gasifier II from the gas-solid fuel nozzle 7 on the top of the gasifier II, and at the same time, adds an appropriate amount of water vapor and air from the top of the gasifier II, mixes with air in the gasifier II, and burns at a high temperature. High-temperature gasification reaction with water vapor to generate syngas fuel; the high-temperature gasification reaction temperature is between 1000~1200℃, which is higher than the tar cracking temperature and lower than the ash melting temperature, which can avoid ash melting or slagging, and pass The incoming high-temperature water vapor promotes the tar in the gas-solid mixture input from the gasifier I to be cracked more completely at high temperature. The amount of water vapor introduced is measured by the flow meter on the water vapor input pipeline; the gasification reaction process must Control the appropriate S/B, the ratio is 1.00~1.65; the ER ratio is 0.18~0.32; the reaction pressure is 0.1~1.2MPa, and the gasification reaction is carried out; in this process, the carbon-containing solids are combined with air and water vapor High temperature gasification reaction occurs. At the same time, tar cracks and reacts with water vapor at a high temperature of 1000~1200℃, and both CO and H 2 Wait for combustible gas, thereby increasing the calorific value of the gas and reducing the tar content in the gas.

[0023] The high-temperature fuel gas generated by the gasification reaction first passes through the gas-solid separator 10 to remove larger solids, and the solid ash falls into the two series-connected ash and slag bins I and II, which are connected to the gas-solid separator 10. There is a valve between them to achieve continuous slag discharge and ensure system sealing; then the gas passes through the heat recovery heat exchanger 11 and exchanges heat with the cooling water pumped in by the water pump 12. The gas is cooled and high temperature water vapor is generated at the same time. The pipeline is fed into the gasifier II to realize heat recovery; the cooled gas finally passes through the circulating water scrubber 13 to further cool and remove smaller dust and impurities to obtain clean synthesis gas.

[0024] The system pressure of the process is adjusted and controlled by a valve at the gas outlet.

[0025] In addition, the synthesis gas prepared by the present invention can not only be used for liquid fuel synthesis, but also can be used as a gas fuel for heating or power generation due to its high calorific value.

[0026] A two-stage high-temperature biomass gasification process equipment for syngas preparation, including: air compressor, feeding device, gasification device, purification cooling device; feeding device, gasification device, purification device arranged in series, air compression The machine is respectively connected with the feeding device and the gasification device. The gasification device is composed of a gasification furnace I and a gasification furnace II in series. The bottom of the gasification furnace I is provided with a compressed air inlet, and the lower part is provided with a feed inlet and a top There is a gas-solid mixture outlet. The upper part of the gasifier II is equipped with a gas-solid fuel nozzle. The gas-solid fuel nozzle is equipped with a gas-solid mixture inlet, a compressed air inlet and a water vapor inlet. The lower part of the gasifier II is equipped with a gas outlet. , There is a ash outlet at the bottom.

[0027] The purification cooling device is mainly composed of a gas-solid separator, a heat recovery heat exchanger, and a washing device in series. The cooling water inlet of the heat recovery heat exchanger is connected with a water pump, and the steam outlet is connected with the gasifier II. The washing device includes a circulating water scrubber 13, a water tank 14, and a circulating pump 15, and the above-mentioned devices are connected through a pipeline.