Petrochemical industries

At petrochemical plants there are numerous gas streams that contain valuable components which need to be recovered and reused. These are typically non-reacted monomers, by-products from reactors, inerts, solvents and carrier gas. There is a nice potential for using CMS membranes for many of these applications, and thereby also save money if complicated systems with columns, refrigeration and compressors can be avoided. A study on separation of alkanes-alkenes was performed by Hagg et alP Their systems were the separation of propane-propene and propan-ethene. As the alkanes-alkenes are chemically and physically quite similar compounds with almost identical critical properties, they must be separated on the basis of their molecular size. The Lennard-Jones diameter is 4.7 A and 5.1 A for propene and propane, respectively hence, a carefully tailored CMS membrane would be able to separate these two components according to the molecular sieving mechanism. A selectivity of 23 for this gas pair was documented at 30 °C, and even much higher selectivity at 50 °C this is believed to be a result of a transition of separation mechanisms for propane at lower temperature propane will 

The largest scale on which membrane technology has been introduced in organic processes so far is in petrochemistry, more specifically in the refining of lubri- 

The solvent dewaxing process involves addition of solvent during the chilling of the waxy feed. The chilling process induces crystallization of the wax and the solvent is added to maintain the fluidity. The wax crystals are filtered by rotating drum filters, resulting in a lube oil filtrate and a slack wax with entrained solvent and oil. In both fractions, the solvent is recovered by successive vaporization and distillation. 

Furfural is another extraction solvent of interest. Hardly permeating through common silicones, the lube oil was concentrated in the permeate stream to such an extent that demixing occurred owing to the limited solubility of the oil in furfural, thus allowing easy solvent recovery [44]. 

In the refining of gasoline, the removal of elemental sulfur from gasoline has been patented. The formed insoluble polysulfides were easily removed by UF or even MF [45]. 

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Many processes, particularly in the petrochemical industries, produce a reactor efiiuent which consists of a mixture of low-boiling components such as hydrogen and methane together with much less... 

There are little or no olefins in crude oil or straight run (direct from crude distillation) products but they are found in refining products, particularly in the fractions coming from conversion of heavy fractions whether or not these processes are thermal or catalytic. The first few compounds of this family are very important raw materials for the petrochemical Industry e.g., ethylene, propylene, and butenes. 

Benzene, toluene and xylenes are used either as solvents or as basic intermediates for the chemical and petrochemical industries. 

T. Sevel, N.HaldPedersen, S. Genders - FORCE Inst., Denmark. CHEMICAL, PETROCHEMICAL INDUSTRY... 

Ethylene is the cornerstone of the world s mam moth petrochemical industry and is produced in vast quantities In a typical year the amount of ethylene produced in the United States (5 x 10 ° lb) exceeds the combined weight of all of its people In one process ethane from natural gas is heated to bring about its dissociation into ethylene and hydrogen... 

Dimerization in concentrated sulfuric acid occurs mainly with those alkenes that form tertiary carbocations In some cases reaction conditions can be developed that favor the formation of higher molecular weight polymers Because these reactions proceed by way of carbocation intermediates the process is referred to as cationic polymerization We made special mention m Section 5 1 of the enormous volume of ethylene and propene production in the petrochemical industry The accompanying box summarizes the principal uses of these alkenes Most of the ethylene is converted to polyethylene, a high molecular weight polymer of ethylene Polyethylene cannot be prepared by cationic polymerization but is the simplest example of a polymer that is produced on a large scale by free radical polymerization... 

T. T. Shih and W. J. Khngebiel, paper presented to The First Shanghai International Sjmposium on Technology of Petroleum and Petrochemical Industry, May 16—20,1989, Shanghai, China. 

The rotating-disk contactor (RDC), developed in the Netherlands (158) in 1951, uses the shearing action of a rapidly rotating disk to interdisperse the phases (Eig. 15b). These contactors have been used widely throughout the world, particularly in the petrochemical industry for furfural [98-01-1] and SO2 extraction, propane deasphalting, sulfolane [126-33-0] extraction for separation of aromatics, and caprolactam (qv) [105-60-2] purification. Columns up to 4.27 m in diameter are in service. An extensive study (159) has provided an excellent theoretical framework for scale-up. A design manual has also been compiled (160). Detailed descriptions and design criteria for the RDC may also be found (161). 

TURBINE fuels), are both in demand. Solvent extraction is also extensively used to meet the growing demand for the high purity aromatics such as ben2ene, toluene, and xylene (BTX) as feedstocks for the petrochemical industry (see BTX PROCESSING FEEDSTOCKS,PETROCHEMICALS). Additionally, the separation of aromatics from aUphatics is one of the largest appHcations of solvent extraction (see Petroleum, refinery processes survey). 

Fan Rating. Axial fans have the capabiUty to do work, ie, static pressure capabiUty, based on their diameter, tip speed, number of blades, and width of blades. A typical fan used in the petrochemical industry has four blades, operates neat 61 m/s tip speed, and can operate against 248.8 Pa (1 in. H2O). A typical performance curve is shown in Figure 11 where both total pressure and velocity pressure are shown, but not static pressure. However, total pressure minus velocity pressure equals static pressure. Velocity pressure is the work done just to collect the air in front of the fan inlet and propel it into the fan throat. No useflil work is done but work is expended. This is called a parasitic loss and must be accounted for when determining power requirements. Some manufacturers fan curves only show pressure capabiUty in terms of static pressure vs flow rate, ignoring the velocity pressure requirement. This can lead to grossly underestimating power requirements. 

It is convenient to divide the petrochemical industry into two general sectors (/) olefins and (2) aromatics and their respective derivatives. Olefins ate straight- or branched-chain unsaturated hydrocarbons, the most important being ethylene (qv), [74-85-1] propjiene (qv) [115-07-17, and butadiene (qv) [106-99-0J. Aromatics are cycHc unsaturated hydrocarbons, the most important being benzene (qv) [71-43-2] toluene (qv) [108-88-3] p- s.y en.e [106-42-3] and (9-xylene [95-47-5] (see Xylenes and ethylbenzene) There are two other large-volume petrochemicals that do not fall easily into either of these two categories ammonia (qv) [7664-41-7] and methanol (qv) [67-56-1]. These two products ate derived primarily from methane [74-82-8] (natural gas) (see Hydrocarbons, c -c ). 

Naphthalene (qv) from coal tar continued to be the feedstock of choice ia both the United States and Germany until the late 1950s, when a shortage of naphthalene coupled with the availabihty of xylenes from a burgeoning petrochemical industry forced many companies to use o-xylene [95-47-6] (8). Air oxidation of 90% pure o-xylene to phthaUc anhydride was commercialized ia 1946 (9,10). An advantage of o-xylene is the theoretical yield to phthaUc anhydride of 1.395 kg/kg. With naphthalene, two of the ten carbon atoms are lost to carbon oxide formation and at most a 1.157-kg/kg yield is possible. Although both are suitable feedstocks, o-xylene is overwhelmingly favored. Coal-tar naphthalene is used ia some cases, eg, where it is readily available from coke operations ia steel mills (see Steel). Naphthalene can be produced by hydrodealkylation of substituted naphthalenes from refinery operations (8), but no refinery-produced napthalene is used as feedstock. Alkyl naphthalenes can be converted directiy to phthaUc anhydride, but at low yields (11,12). 

Several states that have a large number of CPI plants offer various types of tax incentives. Louisiana, for instance, offers a 10-yr tax exemption from property taxes on buildings, equipment, and improvements to land (2). Texas, which has a large petrochemical industry, offers a 7-yr tax abatement program. Neither of these states have a state income tax. Both states offer a tax credit for each job created and provide free worker training. 

Several industries are highly dependent on cheap electric power. These include the aluminum industry, the Portland cement industry, electrochemical industries such as plating and chlorine production, the glass industry, and the pulp and paper industry. Other industries such as the petrochemical industry, which is highly competitive, depend on low priced power. About two-thirds of the cost of producing ammonia is electrical cost. 

Center for Chemical Process Safety. In 1985, the American Institute of Chemical Engineers estabHshed the Center for Chemical Process Safety (CCPS) (New York). The objective of the CCPS was to help prevent catastrophic chemical accidents by compiling information on the latest scientific and engineering practices, safety programs, and adininistrative procedures of the larger members of the chemical industry, so that they can be shared with other (and particularly the smaller) members of the chemical and petrochemical industries. 

Managing Workplace Safety andHealth The Case of Contract Eabor in the U.S. Petrochemical Industry, Appen. 1-A, John Gray Institute, Beaumont, Tex.,... 

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