Hydrodynamics Of A New Multiple-phase Reactor Suitable For Calcium Carbide

With the rapid development of the economy, the demand of the calciumcarbide is increasing. However, the traditional production process of calciumcarbide consumes a large amount of energy and its yield is relatively low. Inview of unbalanced energy structure, exploring a new approach to synthetizecalcium carbide will be an important way to solve the energy problem.According to Zhenyu Liu’s work, we envisaged two kinds of reactors, slurrybubble column reactor and entrained flow reactor, to study the underlyingbasic hydrodynamic properties, which might give useful reference for furtherresearch.Hydrodynamics of bubble was investigated in SBCR with an innerdiameter of0.15m and a height of1.5m by cold model tests. In thisexperiment, tap water as a substitution of liquid CaC2; air and chlorinatedpolyvinyl chloride (CPVC) particles were used as gas phase and solid phase,respectively. The influence of factors, such as superficial gas velocity, liquidheight, internals and feeding rate of solid particles, on flow characteristics,including the average gas holdup, the local average gas holdup, the bubblesize and solid holdup distribution along the axial location was investigated. Important conclusions obtained were:(1) Average bed gas holdup increased with superficial gas velocity. Whenthe hydrostatic height H=0.6m, the average gas holdup would reach themaximum; when internals were existed, the overall average gas holdup of bedlayer was higher than that of bed layer without internals.(2) The local average gas holdup increased with the increase of gasvelocity. According to the experiment, when the hydrostatic height H=0.8m,the local average gas hold reached the highest value.(3) In accordance with the experiments, the local average gas holdupfirstly increased and then decreased along the bed axis at the same superficialgas velocity. The local average gas holdup become maximum when thehydrostatic height H=0.6m.(4) With the increase of superficial gas velocity, the small bubble contentgradually increased while the large bubble content gradually decreased; withthe increase of hydrostatic height, the large bubble content firstly increasedand then decreased; the small bubble content in reactor equipped withinternals was relatively high, besides the content of small bubble increasedwith the pore size of internals decreased.(5) In the certain range of superficial gas velocity, the superficial gasvelocity tended to be uniform when the solid holdup along the axis of thereactor increased. Reduced solid feed rate would optimize axial distribution ofthe solid holdup. The higher the solid feeding rate was, the larger the axial gradient of the solid holdup along the reactor would be.The latter experiment was taken in entrained flow reactor. The reactorwith the diameter of0.2m and height of1.3m. Air was used as gas phase, andchlorinated polyvinyl chloride (CPVC) particle, calcium phosphate were usedas coke power and calcium oxide powder, respectively. In the superficial gasvelocity of29.17~143.75m/s and at the feed rate of0~19.83kg/h, the bedpressure drop, the axial and radial distribution of the local gas velocity andparticle concentration were investigated. Important conclusions obtained were:(1) When gas was the only fiow phase, bed pressure drop increased withthe decrease of the jet gas velocity; the bed pressure drop increased as the jetvelocity increased; when the solid particles feeding rate increase, the bedpressure drop became smaller.(2) Bed local gas velocity along the reactor axis decreased with theincreased jet velocity, when the axial height was at H=0.90m, the localgas speed reached a minimum; at the same gas velocity, bed local gas velocitydecreased with the increase of r/R, the radial distributions of the local gasvelocity in the three regions were uniform.(3) The solid particle concentrations at different axial positions in thereactor was associated with gas velocity: at lower gas velocity, the lower axialposition of the particle concentration distribution was more uniform, with theincrease of the axial position, the concentration of solid particles reduced;when the gas velocity Ug>68.8m/s, the concentration of solid particles along the axial position firstly increased and then decreased and the concentration ofsolid particles reached the peak, when hydrostatic height H=0.4m.(4) Concentration of solid particles in the radial distribution of the reactordecreased as the gas velocity increased. At center of the bed the solidsconcentration was the lowest, while at the side wall, solids concentration wasthe largest. The highest reacting zone, transition zone and preheating zone hadthe same trend.(5) The solid particle concentration at different axial position increasedwith the increased solid feed rate. The radial concentration of solid particleincreased with increased the feed speed; at the same feeding rate, theconcentration of solid particle in three regions monotonically increased fromthe center of the bed to the wall surface of the bed.