根据气力输送的特点,降低动力消耗,节约能源是一个重要的研究课题,从经验中知,管道内径是关于能耗的重要参数。直观上看,当输送量一定时,管径过小,输送易阻滞,管径过大,虽输送畅通,但又造成能量的浪费。根据经验,把管径分成三组,各组的试验结果如下表所示,试用方差分析法比较各组的效果.
管径(mm) | 单位功耗 |
230 | 0.0308,0.0476,0.0504 |
250~260 | 0.0532,0.032,0.0218,0.028,0.028, 0.042,0.0336,0.042,0.042,0.028 |
280~320 | 0.07,0.07,0.0644,0.0312,0.0756,0.0756, 0.07,0.0588,0.0588,0.042,0.0308,0.0364, 0.0448,0.21,0.154,0.1064,0.1288,0.112, 0.1064,0.1288,0.0756,0.0644,0.0504,0.0644, 0.0504,0.0308 |
A.1.0,2
B.1.5,3
C.2,3
D.3,4
一风动设备系统如图所示。贮气筒的工作压强p=686kN/m2(表压强)已知管径d=0.075m,管长L=100m,管路中有7个弯头(ξ弯=0.2),三个三通(ξ三通=0.3),两个阀门(ξ阀门=0.3),一个活结头(ξ接=1.5)。管道中流动处于紊流阻力平方区,其沿程阻力系数λ=0.019/d1/3(d以米计),忽略沿管长的温度变化,空气的重度γa=77N/m3,问:
A.水冲洗、空气吹扫、蒸汽冲洗、化学清洗
B.水冲洗、空气吹扫、蒸汽吹扫、化学冲洗
C.水冲洗、空气吹扫、蒸汽吹扫、化学清洗
D.水清洗洗、空气吹扫、蒸汽吹扫、化学清洗
A.有明显腐蚀和冲刷减薄的弯头、三通、管径突变部位,不包括相邻直管部位
B.需重点管理的管道,其他没有要求
C.需重点管理的管道,其他管道的弯头、三通、管径突变部位及相邻直管部位
D.需重点管理的管道或有明显腐蚀和冲刷减薄的弯头、三通、管径突变部位及相邻直管部位