问题 问答题 简答题

简述文丘里洗涤器的除尘过程。

答案

参考答案:除尘过程分为雾化、凝聚和分离除尘(脱水)三个阶段,前两个阶段在文丘里管内进行,后一阶段在除雾器内进行。

(1)雾化:含尘气体由进气管进入收缩管后,流速逐渐增大,气流的压力能逐渐转变为动能,在喉管入口处,气速达到最大,一般为50~180m/s,洗涤液(一般为水)通过沿喉管周边均匀分布的喷嘴进入,液滴被高速气流雾化。

(2)凝聚:由于气液两相在喉管中的充分混合,尘粒与水滴开始有效的碰撞.凝并,变成更大的颗粒;当水气进入渐扩管时,由于流通断面逐渐扩大.气流速度逐渐降低,此时尘粒与加速的水雾还会有机会再次碰撞。

(3)脱水:已经凝并的尘粒随气流进入脱水器中。由于颗粒较大,在一般的分离器(如惯性除尘器,旋风院尘器)就可以将其分离出来,使气流得到净化。

阅读理解

阅读理解。    

       When Martin was a little boy, he lived in the little town-Holtham. At that time he thought the town

was very big.    

       Well, Martin came back to the town last night. "It's a small town," he thought.  The town has

changed very little in the past forty years, but Martin has changed a great deal. He has grown into a

man. His thoughts are a man's. He sees things through a man's eyes.    

       Martin stayed in the town for five hours. He walked from street to street, but he knew nobody.

Was Holtham, then a town of strangers? No, he suddenly understood it all. Only he was a stranger in

the town.

1. Martin left the town           .      

A. when he was forty      

B. forty years ago      

C. when he was fourteen      

D. five hours ago  

2. In the past years, Martin has changed                    

A. his face      

B. his clothes      

C. a little        

D. a lot    

3. Martin thought the town was a small town because         ,   

A. he saw things through a stranger's eyes      

B. he had been away from the town for too long      

C. he saw things through a man's eyes now      

D. he didn't like the town any longer   

4. Martin           during his five-hour stay in the own.      

A. met no friends      

B. didn't want to see his friends      

C. saw nobody      

D. saw a lot of friends

5. Which of the following is TRUE?      

A. Martin was not a stranger in the town.      

B. Holtham was a town of strangers to Martin.      

C. Great changes have taken place in the town.  

D. A man's thoughts are better than a child's thoughts.

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