The Numerical Simulation Research On Biomass Flow Characteristics In Rotatory Pyrolysis Gasifier

Existing biomass resources reserve of our country is very large, so effic ientbiomass energy could be used through biomass conversion technology. At present,biomass pyrolysis and gasification technology are commonly used in bio-energyconversion technology. But there are some problems in traditional pyrolysis andgasification technologies, such as high tar content in biomass gas, imperfect tarremoval, difficult wastewater treatment. Today’s biomass pyrolysis andgasification are facing the main problem of the high tar content in the biomassgas. In this thesis we use one of the most effective methods to solve the problem.That is biomass high-temperature thermal cracking in the segmentedgasifier(Composition by the rotatory pyrolysis reactor and the rotatorygasification reactor).First, the segmented high-temperature pyrolys is gasifier used in1MWinternal combustion generator set was designed. The basic structure and the sizeof the segmented pyrolysis gasifier have been designed.Numerical simulation of the isothermal gas phase flow fie ld of rotatorypyrolysis reactor with different high-temperature gas flow entrance angle wascarried out by FLUENT software. Found that, when the high-temperature gasflow entrance angle of20°-40°, high-temperature gas flow stream in the rotatorypyrolysis reactor rotated more deeply, the gas phase flow fie ld mixed better. Thennumerical simulation study on adding the discrete phase to the convergent gasflow fie ld in the rotatory pyrolysis reactor has been carryed out. The results showwhen the rotatory pyrolysis reactor’s high-temperature flue gas entrance angle of20°-30°, high-temperature gas flow inlet velocity of40m/s-80m/s, the biomassparticles in the pyrolysis reactor have longer residence time and better mixingdepth.The two-phase flow field coupled calculation was carried out in thesegments high-temperature Pyrolysis gasifier within high temperature gas flowentrance angle of20°-40°.The numerical simulation results show that jetting425K steam in the rotatory gasification reactor has a large influence on the flowdistribution in the rotator pyrolys is reactor;When the high-temperature gas flowwith the velocity of40m/s injecting into the segmented high-temperature Pyrolysis gasifier with entrance angle of20°-40°,The segmented high-temperature pyrolysis gasifier’s collection efficiency of the particulate phase andarrested particals’ residence time changes smaller with entrance angle bigger.In order to investigate non-uniform size of particles’movement in thesegmented high-temperature pyrolysis gasifier, we took the rotatory pyrolys isreactor’s high-temperature gas flow entrance angle of20°for example. The resultshowed that particles of diameter less than0.3mm basically escape from the exit.Particle of diameter more than1mm basically be able to exercise to the bottom ofthe gasifier.