Chlorine processing applications

Aromatic polyamide (aramid) membranes are a copolymer of 1-3 diaminobenzene with 1-3 and 1-4 benzenedicarboxylic acid chlorides. They are usually made into fine hollow fibers, 93 [Lm outer diameter by 43 [Lm inner diameter. Some flat sheet is made for spirals. These membranes are widely used for seawater desalination and to some extent for other process applications. The hollow fibers are capable of veiy high-pressure operation and have considerably greater hydrolytic resistance than does CA. Their packing density in hoUow-fiber form makes them veiy susceptible to colloidal fouling (a permeator 8 inches in diameter contains 3 M fibers), and they have essentially no resistance to chlorine. 

The composition of this alloy (54% nickel, 15% molybdenum, 15% chromium, 5% tungsten and 5% iron) is less susceptible to intergranular corrosion at welds. The presence of chromium in this alloy gives it better resistance to oxidizing conditions than the nickel/molybdenum alloy, particularly for durability in wet chlorine and concentrated hypochlorite solutions, and has many applications in chlorination processes. In cases in which hydrochloric and sulfuric acid solutions contain oxidizing agents such as ferric and cupric ions, it is better to use the nickel/molybdenum/ chromium alloy than the nickel/molybdenum alloy. 

Ni-Cr-Mo Ni-Mo Ni-Cu Chlorination processes Processes involving HCl and nonoxidising acidic chlorides Production and Distillation columns containing acidic chlorides HF alkylation Fluorination Applications where no pitting and no loss of reflectivity are necessary Valves, Bleaching operations Handling Pickling of... 

We have 12 separate filter systems at the site ranging from 333 to 15,000 CFM (Inclosure 23). A typical application is the ADS - the facility used to destroy the nerve agents GB VX by chemical neutralization (Inclosure 2U) GB with NaOH and VX by an acid chlorination process. The actual filter system installation is shown in Inclosure 25 and has a capacity of 15,000 CFM. These filter units consist of a low efficiency particulate prefilter, a high efficiency particulate HEPA filter. 

This section describes the chlorination process, including the physical and chemical factors affecting its efficiency and applicability to specific sites. The equipment, chemical, and operating and maintenance considerations relevant to the three physical forms of chlorine are discussed later. 

This chapter deals with the same topic of chemical oxidation and disinfection, but at the advanced level. Specifically the engineering design and applications of chlorination processes for treatment of wastewater, biosolids, and septage are introduced in detail. 

Mass balance calculations indicate that the sand dewatering beds following the chlorination process were the site of the majority of the organic and nutrient removal. It is possible that after repeated application, the removal capacity of the sand would be exhausted. 

Process applications and limitations Dechlorination process can be used whenever a chlorine residual is undesirable. This usually occurs when the receiving water contains aquatic life sensitive to free chlorine. It is generally required when super-chlorinatiom is practiced or stringent effluent chlorine residuals are dictated. Dechlorination will not destroy chlorinated hydrocarbons already formed in the water or wastewater. It has been reported that about 1% of the chlorine ends up in a variety of stable organic compound when municipal wastes are chlorinated. 

F.Baillou, R. Lisbet,G. Dupre, C. Paillard, J.L. Gustin, "Gas phase explosion of nitrogen trichloride Application to the safety of chlorine plants and chlorination processes , 7 International Symposium on Loss prevention and Safety promotion in the Process Industries. Taormina, Italy, May 1992, Paper n° 106. 

Chlorination has been used to prevent mussel proliferation. The optimisation of the chlorination process depends principally on the mussel growth rate [Whitehouse et al 1985]. At times of low growth rate intermittent chlorination is sufficient, but when mussel growth is rapid the application of chlorine must be continuous or at least semi continuous throughout the growth period. 

There are two crystalline forms widely used in papermaking applications, anatase and rutile. The major difference between the two is crystal uniformity and size, which yields a slightly higher index of refraction in the rutile crystal (Fig. 6.8). There are two chemical processing manufacturing routes commercially viable for titanium dioxide production, the sulphate and the chlorine process. The older sulphate method may be used to produce both anatase and rutile, while the more recent chlorine process is utilised only for rutile crystal production. 

Calendered PE sheet (Crinothene) was used for lampshades. Winothene was a low molecular weight PE made for wax applications. Halothene was a chlorinated PE. None of these proved a growth driver for the PE business. However, a major application for PE was found once ICl Plastics started its first 122 cm (48") film extruder. Today, extmded film (blown film, cast film, extrusion coating) is the major process/application across the main types of PE. 

Gas recycle wastes energy and requires that the machinery be designed for more than the net process flow. The minimum practical amount of recycle is desirable from the standpoint of process efficiency. In chlorine processing, however, safety and process stability perhaps should be given more weight than in many other applications. Most systems have a constant recycle of up to 10% of throughput. 

The presence of amines or any other nitrogen-containing residue in steam condensate restricts its use in process applications. This is especially so when these impurities enter the cells or the chlorine process and eventually form NCI3 (Section 9.1.11.2). 

The present chapter highlights recent developments in photocatalysis that are pertinent to its potential process applicability in water treatment for organic contaminants specifically, (i) mechanism understanding, intermediates and stoichiometry of the overall process (ii) its generality for complete contaminant destruction (mineralization) (iii) some specific contaminant classes of interest (chlorinated aromatics, surfactants, herbicides and pesticides) (iv) kinetics (equations, surface vs. bulk reactions) (v) influence of additional oxidants (vi) use of solar vs. artificial illumination (vii) different catalysts and catalyst s forms (suspended vs. immobilized) (viii) photoreactor design (ix) comparison with other techniques using oxidants and light, with care to the evaluation of efficiency and economics. 

Specific advice was provided regarding ozone feed calculations by Kerwin Rakness (Process Applications Incorporated). Suggestions and comments on chlorine dioxide feed were provided by Kevin Gertig and Grant Jones (both with the City of Fort Collins, Colo.). 

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