Apparatus and Method for Multistage Hierachical Pyrolysis and Gasification of Solid Fuels

An apparatus for multistage hierarchical pyrolysis and gasification of solid fuels, wherein said apparatus for pyrolysis and gasification of solid fuels comprises a feeding device, a multistage fluidized bed reactor, a residue discharging valve, a cyclone and a condenser, comprising:

• a gas inlet is provided at the bottom of the multistage fluidized bed reactor, which is used for injecting gasification agent to the multistage fluidized bed reactor where coal pyrolysis and char gasification reactions occur to obtain pyrolysis and gasification gas with high temperature;
• the multistage fluidized bed reactor consists of a number of stages of fluidized bed which are separated by a number of perforated distributors in the multistage fluidized bed reactor, the top stage fluidized bed being connected with the feeding device;
• the coal fed to the top stage fluidized bed is heated by the char obtained from pyrolysis process in this stage and the mixture of high temperature ascending pyrolysis and gasification gas to be pyrolyzed at a low temperature to generate preliminary pyrolytic solid particles;
• the preliminary pyrolytic solid particles flow downwards through an overflow standpipe;
• the distributor to the next stage fluidized bed to be pyrolyzed further by being heated by high temperature char and the mixture of ascending pyrolysis and gasification gas;
• then the solid particles pass into the next stage fluidized bed to undergo pyrolysis until complete pyrolysis of the coal is realized, thereby obtaining pyrolytic gas and char;
• the char obtained from coal pyrolysis enters into the bottom stage fluidized bed and reacts with gasification agent provided from the bottom of the multistage fluidized bed reactor to implement gasification reactions for producing high temperature gasification gas and solid residue;
• a residue discharging valve is provided at the bottom of the multistage fluidized bed reactor, for discharging the char obtained from pyrolysis or the solid residue obtained from gasification;
• a cyclone is provided at the top of the multistage fluidized bed reactor, for separating the fine powder entrained in the mixture of pyrolysis and gasification gas, wherein the fine powder is returned from the bottom outlet of the cyclone to the multistage fluidized bed reactor through a returning inlet at the bottom of the multistage fluidized bed reactor so as to form a circulation.