Chlorine requirement

On the other hand, wet chlorination of refinery slimes has proven to be a rapid and simple method of obtaining high extractions of selenium from slimes. A simple wet chlorination flow sheet is shown in Figure 3. Slimes chlorination per se is not a simple deselenization operation, but rather a process wherein virtually all the constituents of slimes which form soluble chlorides report as a complex solution of mixed chlorides. Thus the use of wet chlorination requires a complete change in the process to recover the metal values in slimes. The first plant to use wet chlorination of slimes was started by Kennecott (Salt Lake City, Utah) in 1995. 

Like many radical reactions in the laboratory, methane chlorination requires three kinds of steps initiation, propagation, and termination. 

Dangerous materials may require special equipment. Chlorination with gaseous chlorine requires quite expensive storage facilities. Chlorination with chlorine, thionyl chloride, sulphuryl chloride, phosphorus oxychloride, phosphorus trichloride, or phosphorus pentachloride, all of which are fairly hazardous, requires off-gas treatment. Some of these reactants can be recycled. Pyrophoric solids such as hydrogenation catalysts, anhydrous aluminium trichloride for Friedel-Crafts reactions, or hydrides used as reducing agents should usually be handled using special facilities. Therefore, all of the above proce.sses are usually carried out in dedicated plants. 

A detailed supply-chain model, which showed that two days inventory was required to supply the forecast market demand, determined chlorine storage tank number and size. The minimum number of drums and cylinders of liquid chlorine required to be held on-site was also calculated from the supply-chain model. This approach was also extended to calculation of the number and size of storage tanks for products such as caustic soda, sodium hypochlorite and hydrochloric acid. 

Triazine is resistant to electrophilic substitution. Chlorination requires vigorous conditions, and yields are low bromination is a more efficient process (Scheme 6). The reagents employed in the attempted sulfonation or nitration preferentially hydrolyze the ring (63AG(E)309). Recently, Korolev and Mal tseva have reported that 1,3,5-triazine is protonated and hydrated to form the cation shown in equation (2) (75ZOR2613). 

Fifty grams of powdered sulfur are introduced into the flask and heated to 150 °C in an oil bath under the hood while a moderately rapid stream (about 5 bubbles/sec) of dry chlorine is led over the molten sulfur. The crude orange-red product distills rapidly into the receiver. The chlorination requires about two hours and is stopped when only a very small amount of sulfur remains in the reaction flask. About 5-8g of sulfur are added to the crude condensate to combine with the excess of dissolved chlorine a redistillation yields over 90% of the dark yellow chloride boiling at 137-140°C. Large amounts of low-boiling materials must be distilled again from a little sulfur. To obtain a pure product, the material may be fractionated once more or distilled in vacuo b.p. 29-30°C (12mm). 

The production and uses of PCNs have been reviewed previously [5-7, 12,33,34] and thus are only briefly described here. PCNs were produced commercially as complex technical mixtures with trade names which included Halowaxes (USA), Seekay Waxes (UK), Nibren Waxes (Germany), and Clonacire Waxes (France). The synthesis involved the chlorination of molten naphthalene using chlorine gas and metal chlorides (iron(III) or antimony(V)) as catalysts. Reaction temperatures ranged from 80-200 °C depending on the degree of chlorination required, and proceeded as nucleophilic and electrophilic reactions favoring substitution in the a-(l,4,5,8) positions on the naphthalene molecule (Fig. 1) [6]. 

Diorgano tellurium compounds can be easily converted to diorgano tellurium dihalides in reactions with sulfuryl chloride, bromide, and iodide. Carbon tetrachloride, dichlorometh-ane, diethyl ether, petroleum ether, or benzene have been used as reaction media. Chlorinations with sulfuryl chloride, a liquid reagent, avoid the use of gaseous chlorine. Required amounts of sulfuryl chloride can be more easily measured than those of chlorine. Sulfur dioxide formed during the reaction escapes the reaction mixture as a gas, thus facilitating the isolation of the product. For these reasons, sulfuryl chloride has been frequently used, whereas sulfuryl bromide and iodide5-6 have been only infrequently employed. 

Because there appears to be no cost data for chlorinators, we will approximate the cost by using a fixed-tube, shell-and-tube heat exchanger. From Table 2.9, the cost of a 1,000 floating-head heat exchanger in January 1990 was 14,000. As indicated in Table 2.4.1, each chlorinator requires 330 fr of surface area. 

Only 1.808 mol of chlorine is actually available for every 1 mol of sulfur instead of the 4 mol of chlorine required by the balanced chemical equation. Therefore, chlorine is the limiting reactant. 

Chlorine in its free state (HOCl + OCl ) is an effective disinfectant and inactivates most microorganisms in a matter of minutes. However, effective disinfection with chlorine requires careful attention to the following factors. 

Chlorine dosage is the amount of chlorine required to oxidize the target substance to be treated (such as water, wastewater, sludge, or septage) plus the desired chlorine residual. The target substance to be treated is termed chlorine demand. Usually the chlorine dosage is computed as mg/L concentration and the chlorine feed system set at the equivalent Ib/d feed rate. 

The fourth step in design is to select chlorine dosage according to the recommended chlorine dosages in this section, and then calculate chlorine requirements ... 

The fifth step in design is to calculate peak chlorine requirements by the following equation ... 

In most cases, control of breakpoint chlorination requires the use of accurate and reliable automatic equipment to reduce the need for manual process control by operators. However, the operator must give special attention to this equipment and monitoring devices in order to ensure their proper operation. Table 3 indicates how the common process shortcomings can be compensated and improved. Table 4 is a wastewater chlorination process trouble-shooting guide for use by practicing environmental engineers. 

An investigation, of the septage chlorination process were conducted at the Lebanon, Ohio, USA treatment plant which addressed chlorine requirements, dewatering rate, and sand bed underdrainage quality (43). The study concluded the following ... 

CD chlorine dosage, mg/L CR chlorine requirement, Ib/d CT contact time at maximum flow, min CTL contact tank length, ft CTW contact tank width, ft PCR peak chlorine requirements, Ib/d average flow, MGD Qp peak flow, MGD RLW length-to-width ratio SA surface area, ft ... 

Hhis equates to the calculated weight of elemental chlorine required to produce the same amount of hypochlorous acid in water as the given disinfectant e.g., for calcium hypochlorite (70.9g/mol X 2mol/mol x 100)... 

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