Chlorine, removal from refrigerants

Based on the above model for ODP, CH3C1 is removed from the list of refrigerant alternatives together with all other compounds with chlorine. Finally, the two compounds C2H60 and C4H10 are kept for further studies as possible replacements. 

In a suction chiller, chlorine returned from liquefaction boils at compressor suction pressure. Since this pressure is usually close to atmospheric, chlorine will boil at about —34 C, where its heat of vaporization is 288 kJ kg . Returning 15% of the net throughput to the suction chiller can cool the gas to —30°C or lower and allow the compression ratio in the first stage to be increased by about 58%. This technique increases the flow of chlorine through the compressor by the amount of liquid vaporized. In cooling the gas, it removes no heat from the process. The heat load ultimately is transferred to the refrigeration system in liquefaction. 

Chlorine atoms in the stratosphere catalyze the destruction of Earths ozone layer. As we explore further in Chapter 17, evidence tells us that chlorine atoms are generated in the stratosphere as a by-product of human-made chlorofluoro-carbons (CFCs), once widely produced as the cooling fluid of refrigerators and air conditioners. Destruction of the ozone layer is a serious concern because of the role this layer plays in protecting us from the sun s harmful ultraviolet rays. One chlorine atom in the ozone layer, it is estimated, can catalyze the transformation of 100,000 ozone molecules to oxygen molecules in the 1 or 2 years before the chlorine atom is removed by natural processes. 

The products from the primary reactor are cooled in a tubular exchanger and are sent to the main absorber where the major proportion of chlorinated methanes is absorbed in a refrigerated mixture of chloroform and carbon tetrachloride. The stripped gas is scrubbed with dilute muriatic acid to produce a 30-32 per cent HCl solution, thus removing most of the hydrogen chloride. It is then dried. After that it is recycled to the primary reactor. 

The first step in the production of ozone, the photolysis of molecular oxygen [reaction (1)], is rate limiting. While ozone production is slow, there are chemical reactions that can rapidly destroy it. One of the major species that is efficient in the removal of ozone is chlorine. The role of chlorine species in the depletion of ozone has been investigated actively since 1974, when Rowland and Molina [2] drew attention to the potential impact of human-made materials known as chlorofluorocarbons (CFCs) on ozone produced in the stratosphere. Chlorofluorocarbons are widely used in our daily life as refrigerants, aerosol propellants, cleaning solvents, and in fire-extinguishing applications. CFCs are stable, chemically inert, and have low toxicity. These properties make CFCs ideal for many applications and account for their wide use. However, the release of chlorine from the photodissociation of chlorofluorocarbons poses a central threat to ozone produced in the stratosphere ... 

Solvent washing is the removal of organic contaminants from the surface to be cleaned by the use of chlorinated hydrocarbons or other suitable solvents. The solvents frequently used for solvent washing and ultrasonic cleaning are methylene chloride refrigerant 11 (trichlorofluoromethane) refrigerant 113 (trichlorotrifluoroethane) perchloroethylene 1,1,1 -trichlor oethane... 

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