Petrochemical processing

Many separation problems in the petroleum or petrochemical industry occur in gas or vapor phase and at high temperatures. These gas separation applications will be treated in the next chapter. Only those applications involving liquid phase are reviewed here. 

Many chemical products are produced from crude oil. Initially, little chemistry was involved therefore the petrochemicals were not considered part of the chemical process industry. Today, materials ranging from specialised fuels, plastics and synthetics makes it part of the chemical processing, The petroleum refinery is where the chemical processing of oil begins. 

A refinery separates the many types of hydrocarbons present in cmde oils into related fractions of chemically converted, separated hydrocarbon products, and recovers the wastes that are produced. 

The primary process for separating the hydrocarbon components of crude oil is fractional distillation i.e. separation according to the boiling points of the components. These separated fractions are processed further by catalytic reformers, cracking units, alkylation units, or cokers which have there own fractional distillation towers for its products. 

Modem crude oil distillation units are larger than those in the chemical process industry, producing up to 200,000 barrels per day of product. 

There it is heated to about 698 F -depending on the type of crude oil, and the end products desired. A 

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Example 16.2 A problem table analysis of a petrochemicals process reveals that for a minimum temperature difference of 50°C the process requires 9.2 MW of hot utUity, 6.4 MW of cold utility, and the pinch is located at 550°C... 

Properly speaking, steam cracking is not a refining process. A key petrochemical process, it has the purpose of producing ethylene, propylene, butadiene, butenes and aromatics (BTX) mainly from light fractions of crude oil (LPG, naphthas), but also from heavy fractions hydrotreated or not (paraffinic vacuum distillates, residue from hydrocracking HOC). 

Most higher alcohols of commercial importance are primary alcohols secondary alcohols have more limited specialty uses. Detergent range alcohols are apt to be straight chain materials and are made either from natural fats and oils or by petrochemical processes. The plasticizer range alcohols are more likely to be branched chain materials and are made primarily by petrochemical processes. Whereas alcohols made from natural fats and oils are always linear, some petrochemical processes produce linear alcohols and others do not. Industrial manufacturing processes are discussed in Synthetic processes. 

The Alfa-Laval extractor (213) can give up to 20 theoretical stages in one unit. Depending on the system being handled, the capacity of the standard unit ranges between 5.7 and 21.2 m /h (1500—5600 gal/h). Antibiotic extractions and petrochemical processing are typical appHcations. 

Petroleum and Petrochemical Processes. The first large-scale appHcation of extraction was the removal of aromatics from kerosene [8008-20-6J to improve its burning properties. Jet fuel kerosene and lubricating oil, which requite alow aromatics content (see Aviation and OTHER gas... 

Eatty alcohols, prepared from fatty acids or via petrochemical processes, aldol or hydroformylation reactions, or the Ziegler process, react with ammonia or a primary or secondary amine in the presence of a catalyst to form amines (10—12). 

Most reactors have evolved from concentrated efforts focused on one type of reactor. Some processes have emerged from parallel developments using markedly different reactor types. In most cases, the reactor selected for laboratory study has become the reactor type used industrially because further development usually favors extending this technology. Descriptions of some industrially important petrochemical processes and their reactors are available (74—76). Following are illustrative examples of reactor usage, classified according to reactor type. 

A. K. Jaia and S.. Chopra ia X. Chou, ed.. Proceedings of an International Conference on Petroleum Refining and Petrochemical Processing, International Academic PubHshers, Beijing, China, 1991, pp. 368—374. 

Most refinery/petrochemical processes produce ethylene that contains trace amounts of acetylene, which is difficult to remove even with cryogenic distillation. Frequently it is necessary to lower the acetylene concentration from several hundreds ppm to < 10 ppm in order to avoid poisoning catalysts used in subsequent ethylene consuming processes, such as polymeri2ation to polyethylene. This can be accompHshed with catalytic hydrogenation according to the equation. 

A. Chauvel and co-workers. Manual of Economic Analysis of Chemical Processes Feasibility Studies in Eefining and Petrochemical Processes, McGraw-Hid Book Co., Inc., New York, 1980. 

Most petrochemical processes are essentially enclosed and normally vent only a small amount of fugitive emissions. However, the petrochemical processes that use air-oxidation-type reactions normally vent large, continuous amounts of gaseous emissions to the atmosphere (10). Six major petrochemical processes employ reactions using air oxidation. Table 30-5 lists the atmospheric emissions from these processes along with applicable control measures. 

Most centrifugal compressors in service in petroleum or petrochemical processing plants use vane less diffusers. A vaneless diffuser is generally a simple flow channel with parallel walls and does not have any elements inside to guide the flow. 

Corrosion Probiems in Service. The wide variety of corrosive factors that are present in refining and petrochemical processing (e.g., acids, caustics, chlorides, sulfides, sulfates) give rise to a wide variety of corrosive attacks, some of which act ... 

The various forms in which embrittlement can show up in petroleum refining and petrochemical processing... 

The principal use of the alkylation process is the production of high octane aviation and motor gasoline blending stocks by the chemical addition of C2, C3, C4, or C5 olefins or mixtures of these olefins to an iso-paraffin, usually isobutane. Alkylation of benzene with olefins to produce styrene, cumene, and detergent alkylate are petrochemical processes. The alkylation reaction can be promoted by concentrated sulfuric acid, hydrofluoric acid, aluminum chloride, or boron fluoride at low temperatures. Thermal alkylation is possible at high temperatures and very high pressures. 

Industrial Gases in Petrochemical Processing, Harold Gunardson Clathrate Hydrates of Natural Gases Second Edition, Revised and Expanded, E. Dendy Sloan, Jr. 

What is going to be the first area of broad, commercial ionic liquid application This is probably the question most frequently asked of everybody who is active in developing ionic liquid methodology. The answer is not easy to give. Some petrochemical processes are ready to be licensed or are in pilot plant development (as described in Section 5.2), but there is still some time needed to bring these applications on stream and to claim a broad replacement of existing technologies by ionic liquids in this area. For some non-synthetic applications, in contrast, the lead time from the first experiments to full technical realization is much shorter. 

Ludwig, E. E., Petrochemical Process Engineering, Refin-ingEngr., Mar. i960, p. C-8. 

Pumping of liquids is almosl universal in chemical and petrochemical processes. The many different materials being processed require close attention to selection of materials of construction of the various pump parts, shaft sealing, and the hydraulics of the individual problems. A wide variety of qqtes and sizes of pumps have been developed to satisfy the many special conditions found in chemical plant systems however, since all of these cannot be discussed here, the omission of some does not mean that they may not be suitable for a service. 

Fans (or blowers) of large volumes for industrial applications are usually applied to air service, and essentially all manufacturer s performance data/charts/tables are so referenced to standard air however, they can be readily adapted to chemical/petrochemical process applications in which relatively large volumes of clean gas mixtures are processed at low pressures. ... 

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