问题 问答题 简答题

压力容器是如何分类的?

答案

参考答案:

压力容器的分类方法很多,常用的有三种。

(l)按容器承受的压力p,可分为内压容器和外压容器。内压容器又分为低压容器(0.1≤p<1.6MPA.、中压容器(1.6≤p<10MPA.、高压容器(10≤p<l00MPA.、超高压容器(p≥1OOMPA.。

(2)根据容器压力高低和介质的危害程度及在生产过程中的重要作用,将容器分为三类。

l)属于下列情况之一者为一类容器非易燃或无毒介质的低压容器;易燃或有毒介质的低压分离容器和换热器。

2)属于下列情况之一者为二类容器中压容器;剧毒介质的低压容器;易燃或有毒介质的中压分离容器和换热器;内径小于lm的低压废热锅沪。

3)属于下列情况之一者为三类容器高压、超高压容器;剧毒介质且最高工作压力pw与容积V的乘积Pw³V≥0.2MPa²m3的低压容器或剧毒介质的中压容器,易燃或有毒介质且Pw³V≥0.5MPa²m3的中压反应容器,或Pw³V≥5MPa²m3的中压贮运容器;中压废热锅炉或内径大于lm的低压废热锅炉。

(3)根据压力容器在生产过程中的作用原理可分为反应容器、换热容器、分离容器、贮运容器四种。具体划分如下。

l)反应容器主要是用来完成介质的物理、化学反应的容器,如反应器、发生器、反应釜、分解锅、分解塔、聚合釜、高压釜、超高压釜、合成塔、变换炉等。

2)换热容器主要用来完成介质的热量交换的容器,如废热锅炉、热交换器、冷凝器、蒸发器等。

3)分离容器主要是用来完成介质的流体压力平衡和气体的净化分离等的容器,如分离器、过滤器、再沸器,吸收塔、汽提塔、分馏塔、干燥塔等。

4)贮运容器主要是用来盛装生产和生活用的原料气体、液体、液化气体等的容器,如各种形式的贮槽、槽车。

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ASK any group of teenagers in the UK what they most like to eat, and foods like pizzas, curries, pasta, burgers and chips are bound to get a mention – and many young people would probably also list hanging out at the local fast-food restaurant as one of their favorite pastimes.

But what teenagers like to eat is not necessarily what they should be eating. According to the National Diet and Nutrition Survey, far too many young people in the UK between the ages of four and 18 consume too much fat, sugar and salt in their diet and take in too many calories. Meanwhile their intake of starchy carbohydrates (淀粉类碳水化合物), fibre, iron, vitamins and calcium is too low.

For a growing body, eating foods containing plenty of calcium, such as milk, yoghurt and cheese, is particularly important as calcium is essential for the development of healthy, strong bones. Similarly, foods that are rich in iron are good for young, rapidly developing bodies, so red meat, bread, green vegetables, dried fruit and fortified (强化的) breakfast cereals (谷类食物) are also recommended.

It is during our teenage years that lifestyle habits can become entrenched (根深蒂固的), so it is important that young people are educated about what foods are good for them. In 2005, in an attempt to change eating habits and open teenagers’ minds to new flavors and new tastes, celebrity chef Jamie Oliver launched a ‘Feed Me Better’ campaign. As part of a television series, ‘Jamie’s School Dinners’, he worked with teachers and cooks in a number of schools across the UK to provide more healthy, nutritious school meal options. Although the campaign was rather resisted at the beginning, it was generally regarded as a huge success and helped to influence governmental policy on nutritional standards for school meals.

No one expects to end the teenage love affair with fast and junk food but, hopefully, if projects like ‘Feed Me Better’ and the Government's own ‘Change4Life’ campaign continue to give out the right messages, more young people will understand the importance of balancing occasional treats with healthier food options.

小题1:What can we conclude from the first two paragraphs?

A.British teenagers eat too much junk food.

B.British teenagers need to take in more calcium.

C.What British teenagers like to eat is probably what their bodies need

D.British teenagers should reduce their intake of starchy carbohydrates.小题2:Young people need calcium and iron ______.

A.to improve their brainpower

B.to build healthy strong bodies

C.to provide energy for their body

D.to help change their eating habits小题3:According to the article, Jamie Oliver launched a campaign at schools to ______.

A.show off his excellent cooking skills

B.teach students how to cook nutritious meals

C.make the public keep an eye on school food

D.improve the children’s diet at school小题4:Which is a point that the article supports?

A.Teenagers should never eat any junk food at all.

B.It’s easy for children to give up unhealthy eating.

C.It’s okay for a healthy eater to have a little junk food.

D.Once developed, our eating habit will never change.