问题 问答题 简答题

废热锅炉安全运行的影响因素有哪些?

答案

参考答案:

在高温、高压下运行的废锅出现损坏事故的几率相对说来比较大,而损坏事故大多集中在废锅炉管上,废锅炉管爆破损坏的因素很多,情况复杂,归纳起来有以下几个方面:

(1)管壁过热,这是炉管爆破损坏主要的常见的原因。引起炉管管壁过热的主要因素有:热流强度过大,热负荷不均匀,水循环不良和热阻增大等。

(2)管壁腐蚀。炉管管壁腐蚀的主要形式有炉水的酸碱腐蚀,沉积物下的局部腐蚀以及冲刷腐蚀等。

(3)机械损伤和非稳定性热应力损坏。例如制造材料的缺陷,操作中出现的水击、管束震动,热冲击所引起的非稳定性热应力损坏等。

阅读理解

阅读理解。

     Before you go to another country, it's great helpful if you know the language and some of the customs

of that country.

     When people meet each other for the first time in Britain, they say "Hello" or "Nice to meet you" and

shake hands. Usually they don't shake hands when they just meet or say goodbye. But they shake hands

after they haven't met for a long time or when they'll be away from each other for a long time.

     Last year a group of German students went to English for a holiday. Their teacher told them the English

people hardly shake hands. So when they met their English friends at the station, they kept their hands

behind their backs. The English students had learned that the Germans shake hands as often as possible,

so they put their hands in front and got ready to shake hands with them.It made both of them laugh.

1. If you want to travel, it's            for you to know the language and some of the customs of the country

    you're going to visit. [ ]

A. not useful

B. not helpful

C. very helpful

2. English people usually shake hands when they           .[ ]

A. meet every time

B. meet for the first time

C. say goodbye to each other

3. Usually English people don't shake hands           .[ ]

A. when they'll be away for a long time

B. when they just meet or say goodbye

C. after they haven't met for a long time

4. Which of the following is not true? [ ]

A. The Germans shake hands as often as possible

B. The English people hardly shake hands

C. The Germans hardly shake hands

5. This story is about            .[ ]

A. languages

B. customs

C. bowing

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