问题 问答题 简答题

简述加氢催化剂钝化主要步骤?

答案

参考答案:(1)当需要进行催化剂钝化时,改好催化剂钝化相关流程,急冷塔建立水循环,钝化过程保持连续最大送水和补水,防止酸腐蚀。

(2)保持HIC-2252关闭,在HIC2252后连续给氮气,PC-2426自动控制在5kPa,多余的气体通过PC-2426排至尾气焚烧炉。

(3)启动喷射器,在线炉、反应器和急冷塔建立氮气循环;通过调节喷射器蒸汽量,使循环气流量稳定在4000m3/h以上,在线炉熄火且反应器床层温度降至60~70℃。

(4)打开在线炉入口空气阀,引少量空气进入系统,并控制循环气中O2为0.1%。

(5)进入系统的氧气与催化剂成份硫化钴、硫化钼及催化剂上的硫化铁发生反应,转变稳定的氧化钴、氧化钼及氧化铁,使催化剂得到钝化,钝化过程应有控制地进行,通过分析反应器出口气中的O2和SO2含量,确定催化剂的钝化进度,在此期间反应器床层温度不得大于100℃。

(6)急冷塔通过加入净化水,控制急冷水PH为6~8。

(7)逐渐加大循环气中空气加入量,使反应器入口气体中O2含量达到2%(V),反应器床层温度无升高,并通过分析反应器出入口气体组分,确认无化学反应发生。

(8)缓慢加大循环气中空气加入量,使循环气中O2含量达到20%(V),钴/钼催化剂钝化完成。

阅读理解

阅读理解。

     Never try to do your homework when you are hungry. If you decide to do your homework right after

school, you'd better get something to eat before getting to work. Always do your homework before you

get too tired. Don't wait until very late in the evening, or your work will seem much harder than it really is.

     If you have more than one hour's work, give yourself a break after an hour. On the other hand, don't

rest too much or you can't get anything done. You should be able to work about half an hour at a time

without stopping.

     Don't wait to do your homework until the last minute. If you do like this, you will have it on your mind

and you won't enjoy your free time so much. Finishing your everyday homework in time will be enough

to follow what is going on in school and this will give you chance to do well in your exams.

     Do your homework at the same time every evening. This will help you make it a habit. It will make it

easier to do and it will make your free time more enjoyable.

1. What is a better way to do your homework?

A. Eat something before you start doing it.

B. Dd it even if you are hungry.

C. Do it when you are tired.

D. Do it when you have enough sleep. 

2. If you wait very late to do your homework in the evening, it will _____.

A. become very easy

B. seem much harder

C. make you sleep early

D. make you enjoy your free time

3. According to the passage, you can't enjoy your free time because _____.

A. you have to do your homework each night

B. you want to do your homework without mistakes

C. you haven't finish your homework

D. you want to know what's going on in school

4. How many main things are talked about in the passage?

A. 2.

B. 3.

C. 4.

D. 5.

5. What is the main idea of the passage?

A. How to get good marks in school.

B. How to enjoy your free time.

C. Try to do your homework faster and better.

D. Some advice for doing your homework.

材料分析题