The Petrochemical industry

The petrochemical industry, that branch of the chemical industry which is based on the exploitation of the crude-oil distillation products, has turned 

Acetylene is derived from carbide, the latter obtained by a reaction between lime and coke (the major solid fraction obtained from coal pyrolysis). The basic chemical reactions are as follows  

Just another step leads to the manufacture of one of the oldest monomers—vinylchloride—along with other vinyl derivatives (including acrylonitrile). 

Ethylene, which serves as a source of many other monomers, can also be synthesized by the hydrogenation of acetylene. 

Methanol is obtained in another process, by oxidizing coke with steam to form a mixture of carbon monoxide and hydrogen, as follows  

In Chapter 2 we sketched the processes by which petroleum is refined and polyester is made from petroleum fractions and natural gas liquids. In Chapter 3 we sketched the history of the major petrochemical companies and looked at several important single-reaction systems. In this chapter we will consider the evolution of feedstocks and intermediates in the petroleum and chemical industries. 

Recall that the petroleum refining industry involves multiple reactions because crude oil contains an almost infinite number of molecules, and almost the same number of product molecules is produced by each of the reactors we described in Chapter 2. However, in a sense the petroleum refining industry is simply a sophisticated cooking of large molecules to crack them down to smaller molecules. 

The chemical industry typically involves much more high technology but smaller reactors because one usually desires to produce a single molecule as an intermediate to make a particular product. These molecules usually can be sold for a much greater price than gasoline so the extra value added in the petrochemical processing industry justifies the increased sophistication and cost of these reactors. The costs of separating the desired product from reactants and undesired products can dominate the economics of petrochemical processes. 

Even more than the petroleum industry, the petrochemical industry defmes the chemical engineering profession. The evolution of this industry has produced the changes in the country s needs for engineers and continues to evolve and employ most chemical engineers. The raw materials used in chemical synthesis have made the transitions 

The transition from petroleum to light alkanes as direct chemical feedstocks is stiU in progress. 

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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. 

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... 

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 ). 

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. 

A. V. Hahn, The Petrochemical Industry-Markets and Economics, McGraw-HiU Book Co., Inc., New York, 1970. 

Until the end of World War II, coal tar was the main source of these aromatic chemicals. However, the enormously increased demands by the rapidly expanding plastics and synthetic-fiber industries have greatly outstripped the potential supply from coal carbonization. This situation was exacerbated by the cessation of the manufacture in Europe of town gas from coal in the eady 1970s, a process carried out preponderantly in the continuous vertical retorts (CVRs), which has led to production from petroleum. Over 90% of the world production of aromatic chemicals in the 1990s is derived from the petrochemical industry, whereas coal tar is chiefly a source of anticorrosion coatings, wood preservatives, feedstocks for carbon-black manufacture, and binders for road surfacings and electrodes. 

The pattern of commercial production of 1,3-butadiene parallels the overall development of the petrochemical industry. Since its discovery via pyrolysis of various organic materials, butadiene has been manufactured from acetylene as weU as ethanol, both via butanediols (1,3- and 1,4-) as intermediates (see Acetylene-DERIVED chemicals). On a global basis, the importance of these processes has decreased substantially because of the increasing production of butadiene from petroleum sources. China and India stiU convert ethanol to butadiene using the two-step process while Poland and the former USSR use a one-step process (229,230). In the past butadiene also was produced by the dehydrogenation of / -butane and oxydehydrogenation of / -butenes. However, butadiene is now primarily produced as a by-product in the steam cracking of hydrocarbon streams to produce ethylene. Except under market dislocation situations, butadiene is almost exclusively manufactured by this process in the United States, Western Europe, and Japan. 

M. Gans and B. J. Ozero, Hydrocarbon Process. 55(3), 73 (1976) B. DeMaghe, Hydrocarbon Process. 55(3), 78 (1976) D. E. Field and co-workers. Engineering and Cost Study ofAirPollution Controlfor the Petrochemical Industry, Vol. 6, EPA Report No. EPA-450/3-73-006-1, Environmental Protection Agency, Washington, D.C., June, 1975. 

The gas turbine is a power plant that produces a great amount of energy for its size and weight. The gas turbine has round increasing seiwice in the past 15 years in the petrochemical industry and utilities throughout the world. It is the power source of the aircraft industry. In this section we deal with land-based gas turbines. 

R. K. Goyal, Practical Examples of CPQRA from the Petrochemical Industries, Trans. IChemE, 71, Part B, 117-23, 1993. 

In the petrochemical industry close to 80% of reactions are oxidations and hydrogenations, and consequently very exothermic. In addition, profitability requires fast and selective reactions. Fortunately these can be studied nowadays in gradientless reactors. The slightly exothermic reactions and many endothermic processes of the petroleum industry still can use various tubular reactors, as will be shown later. 

Various experimental methods to evaluate the kinetics of flow processes existed even in the last centuty. They developed gradually with the expansion of the petrochemical industry. In the 1940s, conversion versus residence time measurement in tubular reactors was the basic tool for rate evaluations. In the 1950s, differential reactor experiments became popular. Only in the 1960s did the use of Continuous-flow Stirred Tank Reactors (CSTRs) start to spread for kinetic studies. A large variety of CSTRs was used to study heterogeneous (contact) catalytic reactions. These included spinning basket CSTRs as well as many kinds of fixed bed reactors with external or internal recycle pumps (Jankowski 1978, Berty 1984.)... 

In spite of all these problems and difficulties, tubular reactors are the most important equipment for organic intermediate production in the petrochemicals industry. 

Both the Power Industry and the petrochemical industries use the aircraft-type turbine. The Power Industry uses these units in a combined cycle mode for power generation especially in remote areas where the power requirements are less than 100 MW. The petrochemical industry uses these types of turbines on offshore platforms especially for gas re-injection, and as power plants for these offshore platforms, mostly due to their compactness and the ability to be easily replaced and then sent out to be repaired. The aeroderivative gas turbine also is used widely by gas transmission companies and petrochemical plants, especially for many variable speed mechanical drives. These turbines are also used as main drives for Destroyers and Cruise Ships. The benefits of the aeroderivative gas turbines are ... 

In a radial-inflow turbine the problems of erosion and exducer blade vibration are prominent. The size of the particles being entrained decreases with the square root of the turbine wheel diameter. Inlet filtration is suggested for expanders in the petrochemical industry. The filter usually has to... 

With the constant competitive pressures on the petrochemical industry, it is important to operate all plant equipment at the best performance level possible. This is certainly true for compressors. 

The world-wide growth of the petrochemical industry which enabled plastics to be produced at lower cost than from other materials such as coal. 

The development of natural gas as a fuel source in the UK has led to reductions in tar acid supplies and this has prompted the petrochemicals industry to make... 

Ammonium sulfate is produced as a caprolactam by-product from the petrochemical industry, as a coke by-product, and synthetically through reaction of ammonia with sulfuric acid. Only the third process is covered in our discussion. The reaction between anunonia and sulfuric acid produces an ammonium sulfate solution that is continuously circulated through an evaporator to thicken the solution and to produce ammonium sulfate crystals. The crystals are separated from the liquor in a centrifuge, and the liquor is returned to the evaporator. The crystals are fed either to a fluidized bed or to a rotary drum dryer and are screened before bagging or bulk loading. 

In chemical laboratories, small flasks and beakers are used for liquid phase reactions. Here, a charge of reactants is added and brought to reaction temperature. The reaction may be held at this condition for a predetermined time before the product is discharged. This batch reactor is characterized by the varying extent of reaction and properties of the reaction mixture with time. In contrast to the flasks are large cylindrical tubes used in the petrochemical industry for the cracking of hydrocarbons. This process is continuous with reactants in the tubes and the products obtained from the exit. The extent of reaction and properties, such as composition and temperature, depend on the position along the tube and does not depend on the time. 

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