Influence of the Air Distributor form on Flaky Particles Fluidization Characteristics in a Fluidized Bed

Abstract： In this paper, the deceleration method was proposed to investigate the combined effects of particle size, density and air distributor structure on fluidization features of flaky particles. It is shown that the average relative error of the minimum fluidization velocity ( ${{\rm{u}}_{{\rm{mf}}}}$ ) between the experimental and theoretical results found from literature is 12.08 %; as to cone-shaped air distributor, the ${{\rm{u}}_{{\rm{mf}}}}$ of particle in the case of 15° ∧-shaped air distributor is smaller than those in the case of horizontal and 30° ∧-shaped air distributors, while the particles fail to form stable fluidization by using ∨-shaped air distributor. Besides, the experimental correlation formula of flaky particles is derived for the ${\rm{}}{{\rm{u}}_{{\rm{mf}}}}$ using some of experimental data. Meanwhile, the hydrodynamics of 3D gas-solid flaky particles fluidized bed were studied computationally, the computational results show that the bed pressure drop and concentration distribution of particles with different form of air distributor are well in accordance with the experimental results.

Geometrical Design Of Stand Pipe Air Distributors For The Combustion Of Municipal Solid Waste In A Fluidised Bed

Reka bentuk geometri bagi penyalur udara untuk pembakaran sisa buangan sampah perbandaran telah dihasilkan. Reka bentuk baru ini membolehkan bahan tidak terbakar dikeluarkan dengan mudah melalui ruang antara penyalur udara. Turus terbendalir dihasilkan menggunakan turus Perspex di mana udara disalurkan melalui penyalur udara di bawahnya. Untuk mendapatkan reka bentuk geometri yang sesuai, beberapa parameter reka bentuk telah dikaji. Kesan saiz bukaan, kesan jarak antara antara bukaan dan kesan jarak antara penyalur udara telah dikaji untuk mendapatkan reka bentuk geometri yang paling sesuai dan berdasarkan kepada kualiti perbendaliran di dalam turus terbendalir. Saiz bukaan yang dikaji adalah 1.5 mm, 2 mm, 3 mm dan 5 mm. Hasil kajian menunjukkan bukaan 3 mm menghasilkan kualiti perbendaliran yang stabil. Jarak antara bukaan yang dikaji adalah 10 mm, 20 mm, 30 mm dan 40 mm dan didapati buih udara yang terhasil adalah stabil apabila menggunakan jarak antara bukaan 10 mm. Jarak antara penyalur udara yang dikaji adalah 30 mm, 40 mm, 50 mm, 60 mm dan 70 mm. Hasil kajian menunjukkan jarak terbaik dari segi kestabilan buih udara bagi penyalur udara adalah 70 mm. Kata kunci: Penyalur udara; turus terbendalir; saiz bukaan; jarak antara bukaan; jarak penyalur udara The new geometrical design of stand–pipe air distributor for the combustion of the municipal solid waste was presented. The new design of the air distributors enables penetration of incombustible and unburnt carbon through opening between the air distributors, thus providing easy maintenance work. The fluidized bed experimental rig was constructed using Perspex column in which air was supplied through the distributors below it. In order to establish the final geometrical design of the air distributors, several design parameters were investigated. The effect of orifice size, distance between orifice and distance between distributor pipes on the fluidization behaviour were studied. Investigation on the effects of various orifice sizes of 1.5 mm, 2 mm, 3 mm, 4 mm and 5 mm showed that the 3 mm orifice size exhibited the most stable fluidization behaviour. Investigation on some selected orifice distances of 10 mm, 20 mm, 30 mm and 40 mm also found that the 10 mm orifice distance exhibited stable growths of bubbles. Various pipe distances of 30 mm, 40 mm, 50 mm, 60 mm and 70 mm were also investigated and the most suitable pipe distance was 70 mm. Key words: Air distributor; fluidized bed; orifice size; orifice distance; pipe distance