Conversion process

These are the major processes in refining and petrochemicals. In this large group of processes, the following are distinguished  

We will examine hereafter these four large process categories. 

A kinetic model for coal conversion needs to take into account the following conversion processes  

These processes can occur in parallel or subsequently, depending strongly on the process configuration. All of them would require dedicated kinetic expressions. In practice, assumptions are taken to simplify the formulation of the kinetic model (e.g., neglecting tars, inert ash, one pyrolysis gross reaction). 

Because it is decisive for the overall carbon conversion, special emphasis should be placed on the most important conversion process during coal gasification the char conversion. The intention is to establish a coal-adapted kinetic submodel for a CFD case study. 

The techniques used to convert polymer granules to final products are well established, and the main inputs are electricity, thermal fuels, and cooling water. Table 3.3 gives values of these parameters for a selection of processes. At the conversion stage various additives and fillers are usually incorporated into the product. In Table 3.3 these are included in the column headed resin. 

The data of Table 3.3 cannot be regarded as definitive because of the nature of the conversion industry. In particular, note should be taken of the following points  

Materials losses are typically 1-2% and mainly arise from contaminated waste generated during startup, maintenance, and machine pnrging. For injection molding there is also a loss arising from the removal of flashing and sprues such waste can only sometimes be recycled back into the process. 

Few operators monitor separately the energy consumption of the machines and the energy used in space heating and lighting. Conseqnently, the data of Table 3.3 refer to plant performance rather than machine performance. 

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Normally absent or in trace amounts in crude oil, products of conversion processes such as diolefins, acetylenes, etc., are encountered. Table 1.4 gives the physical properties of some of them. Noteworthy is 1-3 butadienerC ( l)... 

Incidentally, numerous petroleum products, particularly those coming from conversion processes, are unstable with respect to oxidation and oxygen analysis is meaningful only if great precautions are taken during sample withdrawal and storage. 

Separation of families by merely increasing the resolution evidently can not be used when the two chemical families have the same molecular formula. This is particularly true for naphthenes and olefins of the formula, C H2 , which also happen to have very similar fragmentation patterns. Resolution of these two molecular types is one of the problems not yet solved by mass spectrometry, despite the efforts of numerous laboratories motivated by the refiner s major interest in being able to make the distinction. Olefins are in fact abundantly present in the products from conversion processes. 

Conversion Processes that generate new molecules having properties adapted to the product s end use. 

Vacuum distillation of the atmospheric residue complements primary distillation, enabli r.ecoyery of heavy distillate cuts from atmospheric residue that will un r o further conversion or will serve as lube oil bases. The vacuum residue containing most of the crude contaminants (metals, salts, sediments, sulfur, nitrogen, asphaltenes, Conradson carbon, etc.) is used in asphalt manufacture, for heavy fuel-oil, or for feed for others conversion processes. 

As a complementary process to reforming, isomerization converts normal paraffins to iso-paraffins, either to prepare streams for other conversions nCi —> /C4 destined for alkylation or to increase the motor and research octane numbers of iight components in the gasoiine pooi, i.e., the C5 or Cs-Ce fractions from primary distillation of the crude, or light gasoline from conversion processes, having low octane numbers. 

Feedstocks are light vacuum distillates and/or heavy ends from crude distillation or heavy vacuum distillates from other conversion processes visbreaking, coking, hydroconversion of atmospheric and vacuum residues, as well as deasphalted oils. 

Due to the conversion process an absorbed photon give rise to less than one electron generated in the CCD. This phenomenon, also called a "quantum sink" shows that the detector is degrading the S/N ratio of the image. The quality of an image being mainly limited by the quantum noise of the absorbed gamma this effect is very important. 

Zeolites are tire product of a hydrotliennal conversion process [28]. As such tliey can be found in sedimentary deposits especially in areas tliat show signs of fonner volcanic activity. There are about 40 naturally occurring zeolite types. Types such as chabazite, clinoptilolite, mordenite and phillipsite occur witli up to 80% phase purity in quite large... 

Figure C3.5.2. VER transitions involved in the decay of vibration Q by cubic and quartic anhannonic coupling (from [M])- Transitions involving discrete vibrations are represented by arrows. Transitions involving phonons (continuous energy states) are represented by wiggly arrows. In (a), the transition denoted (i) is the ladder down-conversion process, where D is annihilated and a lower-energy vibration cu and a phonon co are created.

The formation of a liquid phase from the vapour at any pressure below saturation cannot occur in the absence of a solid surface which serves to nucleate the process. Within a pore, the adsorbed film acts as a nucleus upon which condensation can take place when the relative pressure reaches the figure given by the Kelvin equation. In the converse process of evaporation, the problem of nucleation does not arise the liquid phase is already present and evaporation can occur spontaneously from the meniscus as soon as the pressure is low enough. It is because the processes of condensation and evaporation do not necessarily take place as exact reverses of each other that hysteresis can arise. 

Conventional crude oils Conventional petroleum Convergence methods Conversion processes Convertal... 

Chemical conversion processes can also be used for moisture and oxygen removal. These tend to be the same ones developed for the smaller point-of-use purifiers. Consequently there is Httle economy of scale and they are seldom able to be regenerated. 

Synthesis gas is obtained either from methane reforming or from coal gasification (see Coal conversion processes). Telescoping the methanol carbonylation into an esterification scheme furnishes methyl acetate directly. Thermal decomposition of methyl acetate yields carbon and acetic anhydride,... 

Produced from Co l. Estimates of the cost of producing methanol from coal have been made by the U.S. Department of Energy (DOE) (12,17) and they are more uncertain than those using natural gas. Experience in coal-to-methanol faciUties of the type and size that would offer the most competitive product is limited. The projected costs of coal-derived methanol are considerably higher than those of methanol produced from natural gas. The cost of the production faciUty accounts for most of the increase (11). Coal-derived methanol is not expected to compete with gasoline unless oil prices exceed 0.31/L ( 50/bbl). Successful development of lower cost entrained gasification technologies could reduce the cost so as to make coal-derived methanol competitive at oil prices as low as 0.25/L ( 40/bbl) (17) (see Coal conversion processes). 

A new countercurrent continuous centrifugal extractor developed in the former USSR (214) has the feature that mechanical seals are replaced by Hquid seals with the result that operation and maintenance are simplified the mechanical seals are an operating weak point in most centrifugal extractors. The operating units range between 400 and 1200 mm in diameter, and a capacity of 70 m /h has been reported in service. The extractors have been appHed in coke-oven refining (see Coal conversion processes), erythromycin production, lube oil refining, etc. 

Synthetic Fuel. Solvent extraction has many appHcations in synthetic fuel technology such as the extraction of the Athabasca tar sands (qv) and Irish peat using / -pentane [109-66-0] (238) and a process for treating coal (qv) using a solvent under hydrogen (qv) (239). In the latter case, coal reacts with a minimum amount of hydrogen so that the solvent extracts valuable feedstock components before the soHd residue is burned. Solvent extraction is used in coal Hquefaction processes (240) and synthetic fuel refining (see Coal conversion processes Fuels, synthetic). 

Coal is used ia industry both as a fuel and ia much lower volume as a source of chemicals. In this respect it is like petroleum and natural gas whose consumption also is heavily dominated by fuel use. Coal was once the principal feedstock for chemical production, but ia the 1950s it became more economical to obtain most industrial chemicals from petroleum and gas. Nevertheless, certain chemicals continue to be obtained from coal by traditional routes, and an interest in coal-based chemicals has been maintained in academic and industrial research laboratories. Much of the recent activity in coal conversion has been focused on production of synthetic fuels, but significant progress also has been made on use of coal as a chemical feedstock (see Coal CONVERSION processes). 

The term feedstock in this article refers not only to coal, but also to products and coproducts of coal conversion processes used to meet the raw material needs of the chemical industry. This definition distinguishes between use of coal-derived products for fuels and for chemicals, but this distinction is somewhat arbitrary because the products involved in fuel and chemical appHcations are often identical or related by simple transformations. For example, methanol has been widely promoted and used as a component of motor fuel, but it is also used heavily in the chemical industry. Frequendy, some or all of the chemical products of a coal conversion process are not isolated but used as process fuel. This practice is common in the many coke plants that are now burning coal tar and naphtha in the ovens. 

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