问题 问答题

防止汽轮机超速的措施有哪些?

答案

参考答案:

1.汽轮机大修或调速系统处理缺陷后,应做好调速系统静态试验,调速系统速度变动率迟缓应符合要。

2.机组大修后,甩负荷试验前,运行2000小时以后,都应做超速试验试验。

3.对新装机组或调速系统进行技术改造后,应进行调速系统动态特性试验,甩负荷后的转速飞升值不大于额定转速的6%。

4.汽轮机超速试验时,在调整下不宜停留过长时间,超速试验次数力求减小,试验时,升速应平衡,注意防止转速突升现象。

5.正确调整同步器的调整范围,上限富裕行程不易过大。

6.汽轮机的各项附加保护投入前要严格检查试验动作正常,运行中要保证投入,一旦因故退出运行应有相应的防范措施。

7.高中低压主汽门、调速汽门开关应灵活,严密性合格。

8.按规定定期进行主汽门、调门以及抽汽逆止门活动试验,防止门杆卡涩。

9.主汽门、调门卡涩不动时应及时消除,卡涩不能消除时应停机处理。

10.运行中应检查调门开度与负荷的对应关系,以及调门后的压力变化情况。

11.加强对油质的监督,定期进行油质分析化验。

12.加强蒸汽品质的监督,防止蒸汽带盐使门杆卡涩。

13.运行人员要正确判断机组发生的异常情况(如声音异常,转速指示连续上升,油压升高,振动增大,负荷到零等)遇有转速超过额定转速11%时应紧急停机。

14.在停机时,应注意调门与负荷的对应关系,如有卡涩现象应采取相应的措施,然后再解列停机。

15.汽轮机停运后,应注意防止汽水或杂物进入油系统引起调速系统锈蚀或卡涩。

阅读理解

Many students ask for advice about improving (提高) their English. There are three basic(基本的) questions.

The first question is about real English. Li Hao from Hubei wrote, “I enjoy watching English films and listening to real English songs. But it takes a long time. What do you think?”

This is a great way to learn English! Talk about the film or song with your friends, and guess the meaning of the new words. Just enjoy yourself!

The second question is about speaking. Sam, from Suzhou wrote, “Our school has a foreign teacher. But I'm shy and can’t speak to her. What should I do?”

When I visit China, lots of people in the street say, “Hello! How are you? Where are you from? Do you like China?” These are good questions to start a talk. Many people are shy when they speak English, so before you begin, take a deep breath and smile! Smiling always helps.

The third question is about vocabulary. Oliver, from Anhui wrote, “I want to remember all the new words. I write them down, but I forget them quickly. What should I do?”

Try to remember eight or ten words a day. Write them on pieces of paper and place them in your bedroom. Say the words when you see them, and change them every day. And when you’re shopping, how about counting the English words, or saying the English names for everything you see?

小题1:How many basic questions do the students often ask?

A.Two.

B.Three

C.Four.

D.Five.小题2:What should you do if you are shy to speak English?

A.Watch English films.

B.Write down the words first.

C.Listen to real English songs.

D.Take a deep breath and smile before you begin.小题3:What’s the best title of this passage?

A.How to learn English.

B.Talking about English films.

C.Advice about English writing.

D.The way of beginning an English talk.小题4:Which isn’t a good way to learn English?

A.Listening to English songs.

B.Practising English with a foreigner in the street.

C.Sitting in your bedroom to remember words.

D.Saying the English names for everything you see.

单项选择题 A1/A2型题