The invention provides a technology device and method for preparing propylene by dehydrogenating
propane or
propane-enriching low carbon
hydrocarbon. The device comprises a reacting / regenerating part and a product fractionating part. A reacting / regenerating
system is divided into a parallel type arrangement scheme and a coaxial type arrangement scheme by a
fluidized bed reacting / regenerating technology, wherein a raising
pipe of the parallel type reacting / regenerating
system is an internal or external raising
pipe, and a raising
pipe of the coaxial type reacting / regenerating
system is an external raising pipe. The method comprises the steps: leading raw materials and reaction products to enter into a raising pipe reactor after heat exchange; performing a dehydrogenating
conversion reaction under the conditions that the
reaction temperature is 500-700 DEG C, the pressure is 0.1-0.4MPa, and the ratio of a microspherical catalyst to oil is 5-60, wherein the microspherical catalyst consists of
chromium,
rare earth oxides,
alkali metal oxides and a gamma-Al2O3 carrier, preferably, the temperature is 550-670 DEG C, the pressure is 0.1-0.15MPa, and the ratio of the microspherical catalyst to oil is 6-14; leading the reaction products and the raw materials to enter into a gas-oil separator to separate a
gas phase, a
liquid phase from a water phase after heat exchange and cooling; leading the separated gas to enter into a
gas compressor to be compressed and be transported to an absorbing / stabilizing part; pumping the liquid to an absorbing
tower; transporting the liquefied gas from a return tank at the top of a stabilizing
tower to a propylene /
propane separating
tower by a charging pump of a propylene tower; discharging the fine propylene separated from the top of the tower out of the device as a product; discharging the separated byproduct
hydrogen out of the device; and returning products at bottom of the tower to the reacting / regenerating part to be recycled.