Chlorination heat exchanger

In the chemical industry, titanium is used in heat-exchanger tubing for salt production, in the production of ethylene glycol, ethylene oxide, propylene oxide, and terephthaHc acid, and in industrial wastewater treatment. Titanium is used in environments of aqueous chloride salts, eg, ZnCl2, NH4CI, CaCl2, and MgCl2 chlorine gas chlorinated hydrocarbons and nitric acid. 

Water in Industry. Freshwater for industry can often be replaced by saline or brackish water, usually after sedimentation, filtration, and chlorination (electrical or chemical), or other treatments (22). Such treatment is not necessary for the largest user of water, the electric power industry, which in the United States passed through its heat exchangers in 1990 about 40% of the total supply of surface water, a quantity similar to that used for agriculture, and it was 48% of the combined fresh and saline water withdrawals (10). Single stations of 1000 MW may heat as much as 12 Mm /d by as much as 10—15°C. 

Chlorination of Hydrocarbons or Chlorinated Hydrocarbons. Chlorination at pyrolytic temperatures is often referred to as chlorinolysis because it involves a simultaneous breakdown of the organics and chlorination of the molecular fragments. A number of processes have been described for the production of carbon tetrachloride by the chlorinolysis of various hydrocarbon or chlorinated hydrocarbon waste streams (22—24), but most hterature reports the use of methane as the primary feed. The quantity of carbon tetrachloride produced depends somewhat on the nature of the hydrocarbon starting material but more on the conditions of chlorination. The principal by-product is perchloroethylene with small amounts of hexachloroethane, hexachlorobutadiene, and hexachloroben2ene. In the Hbls process, a 5 1 mixture by volume of chlorine and methane reacts at 650°C the temperature is maintained by control of the gas flow rate. A heat exchanger cools the exit gas to 450°C, and more methane is added to the gas stream in a second reactor. The use of a fluidi2ed-bed-type reactor is known (25,26). Carbon can be chlorinated to carbon tetrachloride in a fluidi2ed bed (27). 

Homogeneous reactions. Homogeneous noncatalytic reactions are normally carried out in a fluidized bed to achieve mixing of the gases and temperature control. The sohds of the bed act as a heat sink or source and facihtate heat transfer from or to the gas or from or to heat-exchange surfaces. Reaclious of this type include chlorination of hydrocarbons or oxidation of gaseous fuels. 

Titanium is the only one of the more common structural metals which is not attacked by wet chlorine gas and it is thus widely used as a heat exchange material for cooling the gas after the electrolysis stage. Preheating of sodium chloride brine is carried out in titanium plate heat exchangers, while titanium butterfly valves, demisters, and precipitators handle the chlorine gas produced in the cell. The most important use of titanium in chlorine production is as anodes in place of graphite in the electrolytic process. This is covered in more detail later. 

Hydrochloric acid Production, purification, recovery, processing Bayonet heaters, heat exchangers, coils, condensers, HCl absorbers, synthetic HCl plants, acid coolers, gas coolers, chlorine burners, strippers, thermometer wells... 

Hydrogen is supplied to the burner in 3 per cent excess over the stoichiometric amount. The conversion of chlorine is essentially 100 per cent. The gases leaving the burner are cooled in a heat exchanger. 

In the first step the chlorine from the tail gas and chlorine feed reacts with the caustic in the jet-loop reactor. The advantage of the jet-loop reactor is that it also acts as a suction device for the gas stream. The residence time of the liquid in step one is dependent on the capacity of the hypochlorite production and liquid level in the tank and varies between 1 and 4 h. A heat exchanger in the loop controls the temperatures in steps one and two. The amount of caustic in the feed-tank of step two is the back-up for failure of chlorine liquefaction. 

Chlorine fluorine exchange between alkyl- or arylehloroboranes and antimony(Ill) fluoride proceeds very readily with evolution of heat. The compounds listed in Table 2 have been obtained by this reaction. 

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