Oxidation Unit

Fig. 6. Snapshot from a dynamic density functional simulation of the self-organisation of the block copolymer PL64 (containing 30 propylene oxide rmd 26 ethylene oxide units (EO)i3(PO)3o(EO)i3) in 70% aqueous solution. The simulation was carried out during 6250 time steps on a 64 x 64 x 64 grid (courtesy of B.A.C. van Vlimmeren and J.G.E.M. Praaije, Groningen).

The number of ethylene oxide units added to the phenoxide depends on the apphcation of the ethoxylate. This chemistry is closely related to the reaction between an alkylphenol and epichlorohyddn which is used ia epoxy resias (qv). 

Synthetic organic chemical manufacturing industry air oxidation unit processes (Subpart III)... 

Polyall lene Oxide Block Copolymers. The higher alkylene oxides derived from propjiene, butylene, styrene (qv), and cyclohexene react with active oxygens in a manner analogous to the reaction of ethylene oxide. Because the hydrophilic oxygen constitutes a smaller proportion of these molecules, the net effect is that the oxides, unlike ethylene oxide, are hydrophobic. The higher oxides are not used commercially as surfactant raw materials except for minor quantities that are employed as chain terminators in polyoxyethylene surfactants to lower the foaming tendency. The hydrophobic nature of propylene oxide units, —CH(CH2)CH20—, has been utilized in several ways in the manufacture of surfactants. Manufacture, properties, and uses of poly(oxyethylene- (9-oxypropylene) have been reviewed (98). 

Diborane reacts with ethylene oxide at —80° C to form diethoxyborane and a soHd polymer containing approximately eight ethylene oxide units per molecule (88). Potassium thiocyanate or thiourea react ia aqueous solution with ethylene oxide to give ethylene sulfide (89). 

Silver-containing catalysts are used exclusively in all commercial ethylene oxide units, although the catalyst composition may vary considerably (129). Nonsdver-based catalysts such as platinum, palladium, chromium, nickel, cobalt, copper ketenide, gold, thorium, and antimony have been investigated, but are only of academic interest (98,130—135). Catalysts using any of the above metals either have very poor selectivities for ethylene oxide production at the conversion levels required for commercial operation, or combust ethylene completely at useful operating temperatures. 

Process Safety Considerations. Unit optimization studies combined with dynamic simulations of the process may identify operating conditions that are unsafe regarding fire safety, equipment damage potential, and operating sensitivity. Several instances of fires and deflagrations in ethylene oxide production units have been reported in the past (160). These incidents have occurred in both the reaction cycle and ethylene oxide refining areas. Therefore, ethylene oxide units should always be designed to prevent the formation of explosive gas mixtures. 

Relative to the process streams, emissions from auxiUary equipment and flares are small. Some ethylene oxide units use gas-fired turbines to feed air or ethylene (109). These result in unbumed hydrocarbon and possible NO emissions. Also, most ethylene oxide units have flares to vent the process gas during upsets. Data is scarce, but estimates indicate that flaring of process gas occurs once to twice a year (109). 

Some catalysts exposed to air stripping off-gas were subject to deactivation. However, using a catalytic oxidizer at a U.S. Coast Guard faciUty (Traverse City, Mich.) for the destmction of benzene, toluene, and xylene stripped from the groundwater, the catalytic oxidization unit operated at 260 to 315°C, and was able to achieve 90% destmction efficiency (see Groundwatermonitoring). 

Seeding Introduction of microorganisms (such as ALKEN CLEAR-FLO 1000 series for aquaculture, 4000 series for grease, and 7000 series for industrial and municipal wastewater) into a biological oxidation unit to minimize the time required to build a biological sludge. Also referred to as inoculation with cultured organisms. 

At Site I, hazards associated with the thermal oxidation unit had not been discussed in site-specific training. In addition, the Site I subcontractor s SSAHP lacked a description of the types of potential emergencies associated with site operations. 

An explosion and fire (March 13, 1991) occurred at an ethylene oxide unit at Union Carbide Chemicals Plastics Co. s Seadrift plant in Port Lavaca, TX, 125 miles southwest of Houston. The blast killed one, injured 19, and idled the facility, that also produces ethylene, ethylene glycol, glycol ether ethanolamines, and polyethylene. Twenty-five residents were evacuated for several hours as a safety precaution. The plant lost all electrical power, for a few days, because its cogeneration unit was damaged. The Seadrift plant, with 1,600 workers, is capable of making 820 million lb per year of ethylene oxide which is one-third of Carbide s worldwide production of antifreeze, polyester fibers, and surfactants Seadrift produces two thirds of Carbide s worldwide production of polyethylene. 

This group has also developed two ring-contraction systems of potential use in crown synthesis. In the first of these, extrusion of a phenylphosphine oxide unit results from treatment with alkoxide ion. In the second, similar conditions initiated decarbonyla-tion of a bis-pyridyl ketone Despite the apparent potential of these methods for crown synthesis, direct formation of crowns by processes which involve them do not appear to have enjoyed great success thus far. 

It is well known that pMMA and pSty in THF follow ideal GPC behavior on many common GPC columns. However, many commercially important acrylate polymers contain a wide array of other monomers. In general, acrylic polymers composed of monomers that do not contain polar groups will yield well-behaved polymers, giving ideal GPC separations. Monomers that contain polar groups should prompt the analyst to carefully evaluate the possibility of adsorption of the analyte onto the column. The most common functionalities of concern are hydroxyl groups, amine groups, ethylene oxide units, and carboxylic acids. In many cases, such monomers can be tolerated. However, the acceptable level can vary considerably with even apparently minor changes in... 

Nowadays economy and ecology render the reuse of the sulfite solution increasingly important. Normally the scrubber liquor is recovered as dilution water directly in the neutralization of sulfonation plant or in the slurry preparation unit of synthetic detergent plants. In some special cases, when the presence of sulfites is incompatible with the slurry composition, it is possible to install as optional a sulfite oxidation unit. This oxidation takes place with atmospheric air. 

Recycle of HBr to bromine is highly desirable both from an economic and an environmental standpoint. Catalytic oxidation offers the potential to recycle HBr from contaminated waste streams to bromine. We have demonstrated that the oxidation catalyst is stable against deactivation by a wide range of contaminants found in waste HBr streams. Strategies to deal with the contaminants will depend on the recycle applications in which the catalytic oxidation unit serves. 

For the organic contaminants, the required bromine product quality wilt also be site specific. If the catalytic oxidation unit is dedicated to a single bromination process, phase separation and drying may be the only purification required. Contaminants in the recovered bromine which are either the starting materials or products of the original bromination reaction should not present a problem if present in bromine recycled to the bromination reactor. In this case, the catalytic reactor would be operated to minimize the formation of undesirable brominated byproducts. For example, if phenol is present in the waste HBr from a tribromo-phenol manufacturing process, minor tribromophenol contamination of the bromine recycled to the reactor should not be a problem. Similarly, fluorobenzene in bromine recycled to a fluorobenzene bromination process should not present a problem. 

A liquid absorption process for the removal of SO2 involves the absorption of the S02 into a solution of ammonia and water with resultant formation of ammonium sulfide. The liquid is then sent to an oxidizing unit to form ammonium sulfate, which can be sold as a by-product or reacted with milk of line to regenerate the ammonia and produce gypsum.28... 

Some related work has been undertaken with aluminum cations150 for purposes of comparison to the anion work. Bimolecular rate constants were measured for the disappearance of Al+ through Aljj. We did not observe a slow rate for the reaction of AI3 which would be expected to have a closed electronic shell and hence would be expected to be comparatively unreactive. However, in the case of the cations, oxidation often leads to the retention of an oxide unit on the cation in contrast to the anion work. 

A plant is producing nitric acid by oxidizing ammonia with air. The gases leaving the oxidation unit are cooled to condense out essentially... 

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