问题 问答题 简答题

本装置的抽提塔和回收塔塔底为什么不控制塔底温度而控制加热蒸汽流量?

答案

参考答案:

苯抽提蒸馏装置的两个塔与一般的精馏塔不同,它们要求塔顶、塔底产品同时合格,而塔底组分较复杂,随着组分和压力变化,温度也变化,如果控制塔底温度为某一数值,以保证产品质量合格将很难,因此采用控制加热介质流量,实际是使通过塔内的气相速率比较稳定,由于加热量是恒定的,它不随进料组成变化而变化,这样可以保证产品质量合格。

阅读理解

Worried about how many calories you will get in that piece of pizza, chocolate cake or bag of chips? A new iPhone application (应用程序) MealSnap may help. Users just need to take a picture of the meal with the phone, and it will give a calorie read-out almost immediately.

MealSnap was developed by DailyBurn, a health social network that focuses on helping its users lead healthier lifestyles. It has created several other health and diet-related iPhone applications. The application gives users a quick reply. To do that, it matches the taken picture to a databank (数据库) with the calorie information of nearly 500,000 kinds of food. Users then get the range of calories for the meal that is photographed.

We started with something simple—an apple. A couple of minutes later, the application replied that it was an apple and between 64 and 96 calories. More impressive was the reply we received after sending a photo of a mixed salad bowl. MealSnap replied that the bowl contained “yellow rice with corn, boiled eggs and beans” and that the food was between 532 and 789 calories.

Mr. Smith, director of DailyBurn, said that usual calorie counting needed a long time, but that the application made it easier to know the calories in food. That is why it is so popular among those who are trying hard to lose weight.

In addition, MealSnap can act as a food diary. No need to write down what they’ve eaten, the photoes will be stored. The users can keep a visual log (视觉的记录). Mr. Smith said, “it’s like a food journey, but easier. All you do is to take the picture. The simple act of recording something can cause a psychological (心理的) change that can help people on their health journey. Knowing the calorie range makes me think more about what I’m eating.”

小题1: The purpose of DailyBurn is to________.

A.help people find ways to lose weight

B.make iPhone more popular

C.persuade people to buy iPhone products

D.help people have a healthy life小题2: What can be learned from the third paragraph?

A.MealSnap is only useful for simple things.

B.The result of MealSnap isn’t always right.

C.MealSnap can also tell what the food is.

D.MealSnap needs a long time to show the calorie range.小题3: Which of the following statements about MealSnap is TRUE?

A.It has been put into the market.

B.People will have a physical change by using it.

C.It’s popular because it was developed by DailyBurn.

D.People have to link iPhone with the Internet to use it.

选择题