问题 单项选择题

天然气的小时流量Q1=5000m3/h,天然气密度ρ1=0.78kg/m3,天然气的压力P1=0.2MPa,天然气温度t=0℃,若选用DN300过滤器,假定△P0=4500Pa时,相应的流量Q0=4400m3/h;若选用DN200过滤器,假定△P0=4500Pa时,Q0=2000m3/h。则填料式过滤器的直径应为()mm。

A.150

B.200

C.250

D.300

答案

参考答案:D

解析:

实际压力△P1可按下式计算。

△P1=1 510.8 Pa<5 000 Pa,因此DN300过滤器可用,但有些偏大;同理可算出DN200过滤器的△P1=7 313 Pa>5 000 Pa,因此DN200过滤器不能满足要求。由于DN200与DN300之间没有标准规格的过滤器,故仍采用DN300过滤器。

选择题
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 Roman Pantheon (万神殿) is one of the greatest achievements of the ancient Romans. The ancient Romans were good architects and they built many wonderful buildings. Another good example of a Roman architectural style is the Roman Coliseum, which is a large building used for public sports events or entertainment. The Roman architectural style has been borrowed by many of the western countries.

The architecture of Pantheon is unique to Rome. In Latin and Greek, pantheon means "Temple of all the Gods". Marcus Agrippa built the original Pantheon in 27 BC. But the Pantheon built by Agrippa was completely destroyed in 80 AD when a fire broke out. The Roman Pantheon that is visited by many tourists today was rebuilt in 125 AD by the Roman emperor Hadrian. Hadrian's architects followed the exact design of Marcus Agrippa. Historians believe that the Pantheon was a place of worship(崇拜) because it housed all the gods and goddesses of the ancient Romans.

The Pantheon of Rome is an amazing example of ancient Roman architecture. This building has been in use for over 2000 years. The Roman Pantheon is famous for its design, size. The most unbelievable feature of this building is its huge concrete dome(圆顶). The Pantheon’s dome was thought to be the largest, until recent times.

Phocas, the Byzantine Emperor presented the Roman Pantheon to Pope Boniface IV to save it from the destruction. In 609 AD, it was turned into a church. During Papal rule, it was used as a burial ground (坟场) for kings and other famous people. There are tombs of Raphael (a painter), King Victor Emmanuel II, King Umberto I and many more in the Pantheon.

Some of the buildings that were constructed on the model of the Roman Pantheon are The Rotunda - University of Virginia, Low Memorial Library - Columbia University, Grand Auditorium - Tsinghua University, Jefferson Memorial - Washington D.C. and Duomo - Florence.

小题1:From the first paragraph, we can learn that _______.

A.the Coliseum was often used for big parties

B.there were different architectural styles in Rome

C.the Roman architectural style was borrowed from many western countries

D.the Pantheon and the Coliseum are examples of Roman architecture小题2:According to historians, the Pantheon was built to _______.

A.exhibit the terrific design of Marcus Agrippa

B.suggest the power of Emperor Hadrian

C.provide a place for Roman gods and goddess

D.show ancient Rome’s unique architectural style小题3:The Pantheon which tourists visit at present was built in _______.

A.27BC

B.80AD

C.about 125AD

D.609 AD小题4:The Pantheon was thought highly of especially because of its _______.

A.strange shape

B.huge dome

C.perfect quality

D.beautiful小题5:The text mainly tells us _______.

A.some facts about the Roman Pantheon

B.the influence of ancient Roman architecture

C.Roman’s lifestyle in ancient times

D.ancient Romans and their architecture