The invention relates to a mutually-cyclical
solid fuel gasification device with double fluidized beds and a
solid fuel gasification method. The method comprises the following steps: performing a
pyrolysis gasification reaction between a
solid fuel and a gas for fluidizations and reactions in a
fluidized bed gasification reactor so as to generate a
combustible gas, as well as solid
coke and semicoke which are not subjected to incomplete
pyrolysis gasification reaction, wherein the heat required by the
pyrolysis reaction is obtained from high-temperature heat-carrying circulating
bed materials; feeding the solid
coke / the semicoke and the heat-carrying circulating
bed materials with heat
discharge into a pneumatic back-feeder through a
cyclone separator or an overflow device according to a running state in the reactor; controllably sending the solid
coke / the semicoke and the heat-carrying circulating
bed materials into a
combustion reactor; reheating the heat-carrying circulating bed materials due to the
combustion of the solid coke / the semicoke in the
combustion reactor; and refeeding the heated heat-carrying circulating bed materials into the gasification reactor through a back-feeding device so as to provide the heat for the pyrolysis gasification reaction. Thus, the device is gasified while the running parameters of the bubbling
fluidization and the fast
fluidization are adapted. As a result, the
solid fuel gasification device provided by the invention has the good adaptability for various combustible solids; and the high running efficiency of the whole device is realized.