Recycling technology features

Description The Uhde (Edeleanu) technology features a two-stage reactor system of which the first reactor is operated in the recycle mode. With this method, a slight expansion of the catalyst bed is achieved that ensures very uniform concentration profiles in the reactor and, most important, avoids hot spot formation. Undesired side reactions, such as the formation of di-ethyl ether (DEE), are minimized. 

Typical products are elastomer modified heterophasic copolymers (heco), as compounded or reactor TPOs. Talc, typically below 20%, is added for higher stiffness and lower coefficient of thermal expansion (LCTE). The latter is an important condition for zero-gap concepts, in which the bumper follows very closely the line of the body fascia. Now that bumpers painted in body colors have become a standard feature, paint adhesion and enhanced surface finish have become important criteria. These can be influenced by optimizing the polymer structure and rubber content. The recycling aspects are treated in the chapter on Bumper recycling technology in this book. 

P r ho. The Paraho retorting technology is similar to the PETROSIX technology except that it can be operated in the direct heat (DH) mode. The unique feature of the Paraho technology is the two levels of heat input (Fig. 4). In the IH mode, the air blower shown in Figure 4 is replaced by a recycle gas heater. The Paraho DH operation has been carried out neat Rifle, Colorado since the 1970s operations to produce asphalt (qv) from shale oil are continuing. 

UNISHALE B. The UNISHALE process, like the Paraho process, uses lump feed and countercurrent flows, and can be operated ia either the DH or IH mode. The UNISHALE B process is an IH process that uses hot recycled gas as the heat-transport medium (Fig. 6). The unique feature of the UNISHALE processes is the rock pump. The soflds move upward through the retort as the vapors are moving downward. The rock pump was used ia the UNISHALE technology at Parachute, Colorado to produce more than 0.64 x 10 m (four million battels) of cmde shale oil. Operations were shut down in 1991. 

A key feature of the DeCaF technology is the recovery and recycling of reagent chemicals, thereby reducing overall chemical consumption and operating costs. 

The recovery of the photocatalyst from the reaction environment represents one of the main problems of the photocatalytic process that limits its industrial application. Although this process step can be obviated by the use of immobilized catalyst, the suspended system has more attractive features [76]. Therefore, the separation of the photocatalyst from the treated solution and its recycle is one of the challenges in further development of this technology. 

Figure 7.13 presents a simplified flowsheet, which concentrates the essential features the balanced VCM technology, as conceptually developed in the previous sections, but this time with the three plants and recycles in place chlorination of ethylene (Rl), thermal cracking of EDC (R2) and oxyclorinahon of ethylene (R3). As mentioned in Section 7.3, from plantwide control three impurities are of particular interest (I]) chloroprene (nbp 332.5 K), (12) trichloroethylene (nbp 359.9K), and (13) tetrachloromethane (nbp 349.8). I, and 12 are bad , since the first can polymerize and plug the equipment, while the second favors the coke formation by EDC pyrolysis. On the contrary, I3 has a catalytic effect on the VCM formation, in some patents being introduced deliberately. 

A reactive distillation (RD) process would bring evident technological and ecological advantages. An important feature is that the reactants can be fed in the stoichiometric ratio ensuring in this way the maximum efficiency of raw materials. Unlike a batch process, where the excess of alcohol is recovered by costly distillation, higher reaction rate can be achieved by internal alcohol recycle. However, the presence of water as a byproduct makes this wish much more difficult than it appears. 

One option from UOP for olefin reduction is the revamp of an FCC unit to RxCat technology (10). In the RxCat process, Figure 4.6, a portion of coked catalyst is recycled to mix with regenerated catalyst at the bottom of the riser reactor. This feature allows the unit to run at a higher catalyst-to-oil ratio and a lower catalyst contact temperature. Moreover, ZSM-5 additive is more effective with RxCat because coked ZSM-5 retains more activity than coked Y zeolite. 

Urea Technologies Inc. (Maxrovic), which offers the Heat Recycle Urea Process (HRUP), whose main feature is the hot recirculation of the aqueous carbamate solution, which enhances the energy balance. This is a conventional technique, operating at 20 to 22.10 Pa absolute. 190 to 200 C, N/C ratio s 4, and once througb CO2 conversion s 71 to 72 per cent... 

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