不同形状垂直筛板流化床性能

Performance of a Fluidized Bed With Vertical Sieve Trays of Different Shapes

用FCC催化剂和空气对垂直筛板流化床的性能进行实验研究。考察了圆型、方型及倒锥型垂直筛板内构件的板孔气速、帽罩孔面积/板孔面积比等筛板结构和流化条件对流化床床层压力降的影响。结果表明,垂直筛板流化床属快速流化床,床内无气泡,颗粒返混小,气-固流化好。板孔气速、筛板结构等对3种垂直筛板床层压力降的影响规律相同。方型垂直筛板的床层压力降最大,圆型与倒锥型垂直筛板的床层压力降相差不大,床层压力降随板孔气速、帽罩底隙高度增加而增大,随固体循环量增加有一最大值,随帽罩孔面积/板孔面积比、板孔径的增大而减小。适宜的帽罩结构尺寸为,板孔面积与帽罩截面积比为0.42,帽罩底隙高与板孔径比0.36～0.64,帽罩孔面积与板孔面积之比大于1.2。最大板孔气速可达6.4m/s。

An investigation of the fluidized bed with vertical sieve trays was carried out by using FCC catalysts and air, including the influences of the gas velocity in tray hole, area ratio of cap hole to tray hole and other structures of the sieve tray, respectively, of round type, square type and opposite taper, and fluidizing conditions on pressure drop of the fluidized bed. The results showed that the fluidized bed with vertical sieve trays belonged to fast fluidized bed with less bubbles, little back-mixing, good fluidization condition. The impacts of the gas velocity in tray hole and the sieve tray structures on the tray pressure drop in three vertical sieve trays were of similar trends. Among the three shapes of vertical sieve trays, the square vertical sieve tray had the highest pressure drop, and the pressure drop of round vertical sieve tray had little difference from opposite taper vertical sieve tray. Pressure drop of the bed increased with the increase of the gas velocity in tray hole and the increase of the bottom clearance height, and existed a maximum value with the rise of circulation rate of solid and decreased with the rise of area ratio of cap hole to tray hole and the tray hole diameter. The suitable sieve tray structural size was that the ratio of tray hole area to cap sectional area was 0.42, ratio of clearance height to tray hole diameter was 0. 36--0. 64, area ratio of cap hole to tray hole was greater than 1.2. The maximum tray hole velocity could reach 6.4 m/s.