NOVELTY - Device for preparing bio-oil from biomass comprises a pyrolysis reactor (1), a gasification reactor (2), combustion reactor (3), a cooler (4), a water heater (5), a biomass dryer, first cyclone dust collector, second cyclone dust collector, a material delivery pipe, return pipe, a storage hopper, a descending pipe, a feeder, and a connecting pipeline. The pyrolysis reactor comprises a biomass feeding port, a gas inlet, a pyrolysis gas outlet and semi-coke outlet. The gasification reactor includes e.g. a semi-coke inlet, steam inlet, a gas product outlet, and a circulating bed material outlet.    USE - Used as a device for preparing bio-oil from biomass.    ADVANTAGE - The device can improve the quality of bio-oil; and has high energy efficiency.    DETAILED DESCRIPTION - Device for preparing bio-oil from biomass comprises a pyrolysis reactor (1), a gasification reactor (2), combustion reactor (3), a cooler (4), a water heater (5), a biomass dryer, first cyclone dust collector, second cyclone dust collector, a material delivery pipe, return pipe, a storage hopper, a descending pipe, a feeder, and a connecting pipeline. The pyrolysis reactor comprises a biomass feeding port and a gas inlet and a pyrolysis gas outlet and semi-coke outlet. The gasification reactor includes a semi-coke inlet, steam inlet, a gas product outlet, a circulating bed material outlet and a slag discharging port. The combustion reactor comprises a gas inlet, an air/oxygen inlet, a circulating bed material inlet, and a smoke/circulation bed material outlet. The cooler comprises a pyrolysis gas inlet, cooling medium inlet, a condensation bio-oil outlet, and a non-condensing gas outlet. The water heater is a dividing wall-type heat exchanger, comprising a high temperature flue gas inlet, a flue gas outlet, a water inlet and a steam outlet. The biomass dryer is a contact-type heat exchanger, comprising a flue gas inlet, a flue gas outlet, a biomass inlet and a dry biomass outlet. The semi-coke outlet of pyrolysis reactor is connected with semi-coke inlet of gasification reactor via material delivery pipe. The pyrolysis gas outlet of pyrolysis reactor is connected with inlet port of first cyclone dust collector. The pyrolysis gas is passed via the pyrolysis gas inlet. The gas product outlet of gasification reactor is connected with the gas inlet of pyrolysis reactor. The circulation bed material outlet of gasification reactor is connected with circulation bed material inlet of combustion reactor via return pipe. The smoke/circulation bed material outlet is connected with second cyclone dust collector inlet. The second cyclone dust collector and a dipleg are directly connected with the combustion reactor. The non-condensing gas outlet of the cooler is connected with the gas inlet of combustion reactor. The gas outlet of second cyclone dust collector is connected with the high temperature flue gas inlet of water heater. The flue gas outlet of water heater is connected with flue gas inlet of the biomass dryer. The steam outlet of water heater is connected with steam inlet of the gasification reactor. The dry biomass outlet of biomass dryer is connected with the storage hopper. The material passes through a hopper outlet into the down pipe and inlet of a feeder, which is connected with the biomass feeding port of pyrolysis reactor. An INDEPENDENT CLAIM is also included for preparing bio-oil from biomass, comprising (i) crushing biomass, conveying into the biomass dryer, and naturally drying the biomass until the moisture content is less than 3%, (ii) conveying the dried biomass orderly into an intermediate storage tank hopper, down pipe and a feeder, and finally conveying it into a pyrolysis reactor, carrying out pyrolysis at a reaction temperature of 400-600 degrees C, where the quick pyrolysis occurs under a reductive atmosphere, and producing biomass pyrolysis gas and pyrolysis semi-coke, (iii) conveying pyrolysis semi-coke via semi-coke outlet of pyrolysis reactor into the gasification reactor by a conveying pipe, and carrying out gasification reaction at 750-900 degrees C to obtain gasification products of hydrogen, carbon monoxide and carbon dioxide, feeding the gasification product into the pyrolysis reactor so that the biomass pyrolysis is carried out in the reduced hydrogen-rich atmosphere, and also provide required amount of heat for pyrolysis, (iv) conveying pyrolysis gases from pyrolysis gases outlet of pyrolysis gases reactor, then conveying gas into a first cyclone dust collector, removing small semi-coke particles carried with the air, and then conveying into a cooler for cooling, separating bio-oil and non-condensing gas after cooling, where one part of is discharged via output device as bio-oil product, and the other part is sent into the cooler via cooling medium inlet and used as bio-oil cooling medium, and (v) conveying the non-condensable gas from the non-condensing gas outlet of cooler into the combustion reactor, which is provided with an air/oxygen inlet, heating the circulating bed material comprising heat carrier of combustion reactor, controlling the operating temperature at 850-1000 degrees C, passing the combustion flue gas from the circulating bed material through the second cyclone dust collector into gasification reactor via dipleg to provide heat for the semi-coke gasification, and conveying the high temperature flue gas from the gas outlet of second cyclone dust collector into the water heater, and then passing into the biomass dryer and discharging.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic representation of the device for preparing bio-oil from biomass.    Pyrolysis reactor (1)    Gasification reactor (2)    Combustion reactor (3)    Cooler (4)    Water heater (5)