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题目：Carbon Dioxide and Global Warming

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Carbon Dioxide and Global Warming

Abstract

Carbon dioxide plays a very important role in the process of global warming. In order to reduce the level of CO2in the atmosphere, two main measures can be taken, carbon dioxide emission reduction and utilization of CO2.

Introduction

Since 1985, scientists" Villach meeting on global warming and its consequent climate change, great efforts have been taken to study global warming (Houghton, 1990). According to their researches, global warming is unequivocal, as is manifested in three internationally global temperature records with the global average temperature rising at a rate of 0.70-0.75 ℃per 100 years during 1910-2009(Wen et al., 2011). Global temperature increase will cause a series of negative effects on natural systems, including snow and ice melting, sea-level rising and intermingle in the hydrological cycle. At the same time the increase in CO2concentrations will lead to the acidification of sea water. Such effects will directly or indirectly threaten terrestrial and marine ecosystems and social systems (FANG Jing-Yun et al, 2011).

As a main greenhouse gas, carbon dioxide has attracted many countries’ attention since 1980. Statistics indicated, because of the burning of the fossil fuels, 185 -242 billion ton CO2were released into the atmosphere per year (YuTian-Jie et al., 2008). Recently, with the development of natural gas, the content of carbon dioxide in the natural gas is also increasing year by year. The large number of CO2emissions, not only causes waste of carbon resource, but also contributes to the global warming. In order to improve the situation, "Kyoto Protocol" was put forward to limit developed countries to reduce the emission of CO2. Therefore, American, Britain and

Germany all researched to make a reduction system. Meanwhile, Japan started to increase the speed of study of CO2, planed to build an independent industry system to take CO2as the chemical material (Yu Tian-Jie et al, 2008).Carbon dioxide is closely related to global warming, its emission reduction and utilization are no delay.

The relationship of carbon dioxide and global warming

Carbon dioxide is an important reactor of global warming. In 2008, Shi Guang-Yu worked in Chinese Academy of S ciences’ Institute of Physics summarized that if double the amount of carbon dioxide in the atmosphere, the density will increase about 3.75W／m2(Shi Guang-Yu, 2008.) . Carbon dioxide affects global warming in many ways, for example it can make the solar short wave radiation passed freely and absorbs the long wave from the surface of earth.

However carbon dioxide is not the only reason resulting in global warming. Cao Gen-Hua and his partners put forward two evidences to prove that global warming was not entirely caused by CO2in their literature “Discussion on the Carbon Dioxide and G reenhouse effect”. Firstly, basing on the long research of climate change, scientists discovered that the records of temperature were not entirely consistent with the content change of carbon dioxide in the atmosphere. Although the carbon dioxide is increasing, the trend was stopped three times by cold period while the increasing of temperature was not stopped. Secondly, if excessive carbon dioxide emissions entirely cause global warming, the cloud cover will also increase and temperature rising will be offset by reducing the earth’s surface heat from the sun. (Cao Hua-Gen et al, 2008)

The utilization technologies of carbon dioxide

Technologies of physics utilization

Carbon dioxide is widely used in psychics, such fire extinguishing agent, refrigerant and cleaning agent. In mid May, 2004, China"s first liquid carbon dioxide dry cleaning machine located in Beijing. As a new cleaning agent, carbon dioxide has

a great effect on cleaning textiles. Compared with traditional methods, it has four main advantages： 1. Using carbon dioxide as the solvent, dry cleaning equipment can realize true green dry cleaning ; 2. The use of liquid carbon dioxide can help dry cleaning machine reduce operating costs and save energy;

3.Liquid carbon dioxide has good washing effect;

4. The mechanical property of liquid carbon dioxide dry cleaning machine is superior. (Qi Da-Tong, 2004)

Carbon dioxide also has many applications in the food industry. They can be summarized three categories.

1. High density of carbon dioxide has great effects on the sterilization disinfection.

2. Carbon dioxide is an inert medium. For it doesn’t damage the various range of food components, the carbon dioxide and carbon dioxide gas in puffed food production are very popular.

3. Carbon dioxide can also be used to produce a king of popular drinks-sodas.

Technologies of chemical utilization

Expect for physics, carbon dioxide is also used in the chemical industry as a chemical martial. For example, the synthesis of urea, urea is a very important fertilizer, under certain conditions. It can be synthesized from NH3and CO2. The chemical equation is as follows:

2 NH3+ CO2→NH2COONH4→CO (NH2) 2+ H2O based on the equation, 740 kg of carbon dioxide will be consumed to produce one ton urea. Because all of the crops’ growths need urea, it is in a great demand. Large amount of carbon dioxide can be consumed. Besides the synthesis of urea, many other developed technologies taking CO2as the material have been used in the Synthesis of salicylic acid, production of sodium carbonate, calcium carbonate and other inorganic carbonate. In addition, as a resource rich in carbon and oxygen, people are also trying to use carbon dioxide in the productions of hydrocarbon, methanol, ethylene carbonate, diethyl carbonate and polycarbonate Etc.

In addition to researching the technologies to use CO2, trying to reduce the emission of CO2is also very helpful to govern global warming.

The emission reduction of carbon dioxide in chemical engineering

The utilization of carbon dioxide in chemical engineering is one of the most important means in the emissions reduction of carbon dioxide, especially in large-scale chemical production, the large use of carbon dioxide playing a decisive role on the emission reduction. Take an example: Currently, the quantity of ammonia plant probably reaches to 500. Take the medium-plant as an object. If the carbon dioxide emissions can be recycle, each plant will get 30000-50000tons carbon dioxide products and the total will reach 1.65-2.75millions ton per year.

The synthesis of urea is the most successful example to fixed and use large mass of carbon dioxide. With the continuous progress of chemical engineering utilization technologies of carbon dioxide, chemical engineering of carbon dioxide has become the main means of carbon dioxide emissions reduction. Then how to use the developed chemical technology to reduce carbon dioxide emissions and how to achieve the reliable combination of the technologies to deal with carbon dioxide and reduce carbon dioxide emissions, are particularly important.

Adjust the process of production and reduce the emission of carbon dioxide One of the main sources of carbon dioxide from the chemical industry is the by-product gas in the production of hydrogen. Synthetic gas with hydrogen, carbon monoxide as main component will be produced after oil, coal and natural gas vaporization at the high temperature. Then the carbon monoxide will be converted into hydrogen and carbon dioxide. In reality, with the chemical industry chain of one carbon keeps on developing, carbon monoxide, as the raw material, will have greater value be used more widely. If people adjust the process and structure of production and utilize the carbon monoxide resource appropriately, the amount of carbon monoxide’s conversion will reduce and the generation and emission of carbon dioxide

will be under control. （Yu Tian-Jie，2008）

Conclusion

Global warming is a huge challenge we mankind are facing today. Reducing the content of carbon dioxide in the atmosphere is one of the important measures to improve global warming. The utilization and emission reduction of carbon dioxide are the two main ways to reduce the level of carbon dioxide in the atmosphere.

Realizing the wide utilization of carbon dioxide is still far away to us.

Currently, making full use of carbon monoxide and reducing the carbon dioxide conversed from carbon monoxide are the two most efficient measures to reduce the emissions of carbon dioxide in the process of chemical industry. At the same time, carbon dioxide from other chemical production can be collected to use in the synthesis of urea, soda ash and carbonates. Because the technologies to produce those chemical productions are very mature, the most important step is to combine those technologies efficiently for the realization of emission reduction and maximum utilization of carbon dioxide.

Reference

Fang Jing-Yun, ZHU Jiang-Ling et al, 2011 Global warming, human-induced carbon emissions and their uncertainties.

Houghton, 1990. Scientific assessment of climate change.

Shi Guang-Yu, 2008. Impacts of CO2and other factors on Global Warming.

Wen Ching-Yang, 2011. Particuology and climate change

Yu Tian-Jie，2008. The Chemical Use and Emissions of Carbon Dioxide

齐大同，2004. 中国洗衣业的突破性进展--浅谈液体二氧化碳干洗机在洗衣业的应用

曹根华、李玉杰等, 2008. 浅谈二氧化碳对温室效应的影响

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