Chlorine processing pressure

The process involving aHyl alcohol has not been iadustriaHy adopted because of the high production cost of this alcohol However, if the aHyl alcohol production cost can be markedly reduced, and also if the evaluated cost of hydrogen chloride, which is obtained as a by-product from the substitutive chlorination reaction, is cheap, then this process would have commercial potential. The high temperature propylene—chlorination process was started by SheH Chemical Corporation ia 1945 as an iadustrial process (1). The reaction conditions are a temperature of 500°C, residence time 2—3 s, pressure 1.5 MPa (218 psi), and an excess of propylene to chlorine. The yield of aHyl chloride is 75—80% and the main by-product is dichloropropane, which is obtained as a result of addition of chlorine. Other by-products iaclude monochioropropenes, dichloropropenes, 1,5-hexadiene. At low temperatures, the amount of... 

Hexachloroethane is formed in minor amounts in many industrial chlorination processes designed to produce lower chlorinated hydrocarbons, usually via a sequential chlorination step. Chlorination of tetrachloroethylene, in the presence of ferric chloride, at 100—140°C is one convenient method of preparing hexachloroethane (142). Oxychlorination of tetrachloroethylene, using a copper chloride catalyst (143) has also been used. Photochemical chlorination of tetrachloroethylene under pressure and below 60°C has been studied (144) and patented as a method of producing hexachloroethane (145), as has recovery of hexachloroethane from a mixture of other perchlorinated hydrocarbon derivatives via crystalH2ation in carbon tetrachloride. Chlorination of hexachlorobutadiene has also been used to produce hexachloroethane (146). 

Refining and Isomerization. Whatever chlorination process is used, the cmde product is separated by distillation. In successive steps, residual butadiene is stripped for recycle, impurities boiling between butadiene (—5° C) and 3,4-dichloto-l-butene [760-23-6] (123°C) are separated and discarded, the 3,4 isomer is produced, and 1,4 isomers (140—150°C) are separated from higher boiling by-products. Distillation is typically carried out continuously at reduced pressure in corrosion-resistant columns. Ferrous materials are avoided because of catalytic effects of dissolved metal as well as unacceptable corrosion rates. Nickel is satisfactory as long as the process streams are kept extremely dry. 

Detailed guidelines are presented for the correct moulding of TempRite chlorinated PVC industrial moulding compounds. Information is included for the correct selection of equipment and operating conditions, and includes details of melt preparation, mould design, processing, pressures, startup, process upsets, and troubleshooting. 

Example 17.11 A flow of 25,000 m /d of treated water is to be disinfected using chlorine in pressurized steel cylinders. The raw water comes from a reservoir where the water from the watershed has a very low alkalinity. With this low raw-water alkalinity, coupled with the use of alum in the coagulation process, the alkalinity of the treated water when it finally arrives at the chlorination tank is practically zero. Calculate the amount of alkalinity required to neutralize the acid produced during the addition of the chlorine gas. 

Some of the important but expensive rare metals are usually extracted as by-products of other metal separation processes. Selenium and tellurium are recoverable from copper refinery slime by pressure leaching (M40), scandium from uranium plant iron sludge (R15), uranium from gold cyanida-tion residues (G3), silver from aqueous chlorination process for the treatment of slimes, and gravity concentrates from gold ores (V2). A host of other processes are in use. 

Material Balance of a Chlorination Process with Recycle 5 Data of a Steam Generator for Making 250,000 Ib/hr at 450 psia and 650°F from Water Entering at 220°F 9 Steam Plant Cycle for Generation of Power and Low Pressure Process Steam 11... 

The practical advantages of textile plasma exposure have been documented by Rakowski [9], who compared conventional chlorination process with a new process based on the exposure of wool to a low pressure plasma using the apparatus shown schematically in Fig. 14-6. Wool tow is fed continously into a vacuum... 

Kellogg Chlorine Process. The Kellogg process uses 1% nitrosylsulfuric acid [7782-78-7] catalyst and a dissimilar material containing a day desiccant having a reversible water content of 0.5 wt% and a crystalline structure stable to at least 760°C (72,73). Montmorillonite [1318-93-0] is the desired clay desiccant. It absorbs water as it forms, shifting the equilibrium of equation 28 to the right. The basic reaction is carried out on a fluidized bed in which the solids run countercurrent to the gaseous reactants at a temperature of 400—500°C and pressures of 300—1200 kPa (3—12 atm). Nitrosylsulfuric acid catalyst is fed into the top of the stripper column where it reacts with HQ to form nitrosyl chloride which then reacts with 02 in the oxidizer to produce Clg. 

Feedstocks for the chlorination process are ethylene and chlorine. The chlorination of ethylene takes place in the liquid phase at 50-100°C (120-212°F) and slightly above atmospheric pressure. Ferric chloride is the homogeneous catalyst for this process. It is very efficient and highly selective. Selectivity to ethylene dichloride is better than 99%. Compared to oxychlo-rination, the chlorination step is more economical and efficient. However, oxychlorination is necessary to consume the hydrochloric acid formed in the EDC pyrolysis step. 

The actual oxygen requirement may vary from 0.127 to 0.190 lb. per pound of vinyl chloride depending on the particular process licensor. The pressure requirement can also vary from 50-80 psig up to 230 psig. The values given in Figure 18, however, are typical and can be used to estimate the capacity and delivery pressure for an on-site oxygen plant for the oxy-chlorination process. 

The next two sections discuss protection against process hazards that are peculiar to chlorine processing. Section 9.1.10 covers emergency pressure relief both before and after the compressors. An important part of the discussion covers the design and operation of vent scrubbers to prevent the release of chlorine to the environment. Section 9.1.11 is dedicated to the explosion hazards presented by hydrogen and nitrogen trichloride. The sources of NCI3 are discussed, as well as its fate in the process. This includes the mechanisms of accumulation and safe decomposition. 

The water seal is installed somewhere on the low-pressure side of the chlorine process, usually between the cell room and the cooling process of Fig. 9.12. It is in communication with the process by a branch on the main chlorine header, as indicated by Fig. 9.44. The branch line terminates inside the seal vessel, slightly below the surface of a pool of water. When the pressure in the gas line exceeds the difference between the water level and the bottom of the branch line, the seal breaks and gas escapes. A source of brine can be used in place of water consideration of the difference in density then is necessary when setting the height of the seal. 

Chlorine under pressure can be destroyed by sparging it into a tank containing an alkaline solution. The absorption process in this case also is liquid-film controlled [92]. 

Returned vehicles and shipping containers frequently are emptied before reuse or to allow maintenance and revalving. Once the operators have established that the chlorine is free of dangerous contaminants, they can rework it at a rate determined by the capability of the process. While the chlorine is nearly always dry and often at or above process pressure, it is a common practice to introduce it to the inlet of the chlorine dryers. Its rate of entry into the process must be limited, and Section 11.3.2.3B describes the need for control and protective systems. 

Mercury process. Pressure control is a bit more difficult than in the low-pressure membrane-cell process but not very much different. The chlorine gas usually is very low in oxygen and hydrogen content, unless a problem in brine treatment allows some metal contaminant to produce unsafe quantities of hydrogen in the chlorine. The presence of hydrogen is most frequently a problem with mercury cells. 

The whole chlorine processing train can be upset if air enters the system through a vacuum break. If the pressure in the chlorine header is close to the point where the vacuum seal opens, the chlorine compressor should be shut down. This will prevent air from being drawn into the whole chlorine handling system. 

C. Local Measurements. Local measurements of wet chlorine gas pressures below 10 or 15 kPa can be made with U-tube manometers filled with water. Process connections should minimize the collection of condensate in the manometers. A simple but not foolproof technique is to make a connection in the upper half of the header and force the tubing to rise for some distance before descending to the manometer. 

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