Dual component processing

Visualizing the reaction to a load (without time) by such a dual-component interpretation is valuable to our understanding of the creep process but is basically meaningless for design purposes. For this reason the designer is interested in the actual deformation or product failure over a specific time span. Observations of the amount of strain at certain time intervals must be made,... 

FIGURE 19.77 Schematic of the electrophotographic process. Dual component development is shown with hot roll fusing and coronas for charging and cleaning. Source Durbeck, R.C. and Sherr, S. 1988. Hardcopy Output Devices. 

Moulded cushions tend to have slightly better fire retardancy and better resilience properties than slab-stock products. Hot-cure and, more recently, cold-cure moulding techniques have allowed better control of the side reactions (such as formation of isocyanurate and allophanate cross-links). One-shot processing with low-pressure dual-component dispensing equip-... 

Modem approaches in the field of hybrid materials for advanced applications use dual cure processing which, depending on the nature of components, may be (a) a UV-cure followed by a thermal treatment, or (b) a UV-cure followed by a... 

Starch is a polysaccharide found in many plant species. Com and potatoes are two common sources of industrial starch. The composition of starch varies somewhat in terms of the amount of branching of the polymer chains (11). Its principal use as a flocculant is in the Bayer process for extracting aluminum from bauxite ore. The digestion of bauxite in sodium hydroxide solution produces a suspension of finely divided iron minerals and siUcates, called red mud, in a highly alkaline Hquor. Starch is used to settle the red mud so that relatively pure alumina can be produced from the clarified Hquor. It has been largely replaced by acryHc acid and acrylamide-based (11,12) polymers, although a number of plants stiH add some starch in addition to synthetic polymers to reduce the level of residual suspended soHds in the Hquor. Starch [9005-25-8] can be modified with various reagents to produce semisynthetic polymers. The principal one of these is cationic starch, which is used as a retention aid in paper production as a component of a dual system (13,14) or a microparticle system (15). 

Paraffin Isomerization. Another weU-estabhshed commercial process which employs zeoflte catalysts is the isomerization of normal paraffins into higher octane, branched isomers. The catalyst for the Hysomet process of the Shell Oil Co. is dual-functional, and consists of a highly acidic, latge-pote zeoflte loaded with a small amount of a noble-metal hydrogenation component. This catalyst possesses the same... 

The process of designing a pyrotechnic mixture begins with the selection of oxidizer and fuel, and proceeds to incorporate additional components to achieve the exact pyrotechnic effect and bum rate desired in the end item. It is at this point that pyrotechnics takes on the dual nature of an art and science, and experience is often the only thing that can be reHed upon for the solution of a difficult problem. 

Powerforming is basically a conversion process in which catalytically promoted chemical reactions convert low octane feed components into high octane products. The key to a good reforming process is a highly selective dual-function catalyst. The dual nature of this catalyst relates to the two separate catalyst functions atomically dispersed platinum to provide... 

In many cases there is an interaction between the carrier and the active component of the catalyst so that the character of the active surface will change. For example, the electronic character of the supported catalyst may be influenced by the transfer of electrons across the catalyst-carrier interface. In some cases the carrier itself has a catalytic activity for the primary reaction, an intermediate reaction, or a subsequent reaction, and a dual-function catalyst is thereby obtained. Materials of this type are widely employed in reforming processes. There are other cases where the interaction of the catalyst and support are much more subtle and difficult to label. For example, the crystal size and structure of supported metal catalysts as well as the manner in which the metal is dispersed can be influenced by the nature of the support material. 

A dual-bed catalyst system has been developed to tackle the key problems in benzene product impurity during heavy aromatics transalkylation processing over metal-supported zeolite catalysts. It was found that by introducing zeolite H-Beta as a complementary component to the conventional single-bed Pt/ZSM-12 catalyst, the cascaded dual-bed catalyst shows synergistic effect not only in catalytic stability but also in adjustments of benzene product purity and product yields and hence should represent a versatile catalyst system for heavy aromatics transalkylation. 

There is no standard or specification within the industry which specifies the dual redundancy for PLCs used for process control functions. The requirement for control system redundancy is primarily a function of the desired availability or demand of the process control system. Most control sytem availability percentages are in the range of 99 to 99.9%. Depending on the type of PLC system configuration defined, availability generally improves in relation to the amount of redundancy added to the various system components, but does not necessarily improve system reliability. 

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