Petroleum cokes

Coal tar contains an estimated 10,000 compounds, many of which are important organic chemicals. The use of coal tar as a source of these compounds has been largely relegated to a position below numerous synthetic processes, primarily based on petroleum. Fractionation of coal tar yields the following (approximate temperatures and yields given)  

5% Light oil syn. coal tar distillates, coal tar solvents, or coal tar oil. a highly flammable mixture of toluene, xylene, cumenes, etc. 

a dark brown or black residue of toxic aromatic hydrocarbons and other compounds often used as road and roofing tar. Prilled coal tar is coal tar pitch manufactured into small globules or granules. 

Coal tar naphtha (71-43-2) is an indefinite term generally applied to the flammable coal tar distillates extracted at around 160 to 220°C. The term naphtha, however, is mostly applicable to petroleum products. Cresol (1319-77-3) is a mixture of methyl phenyl isomers extracted from the middle- to heavy-oil fractions (it is also derived from petroleum). Cresol is a toxic irritant and corrosive to skin and mucous membranes, which explains its common use as a disinfectant. 

Blau gas syn. Fischer-Tropsch gas, synthesis gas, water gas is a mixture of carbon monoxide and hydrogen gas generated from passing steam over hot coal (the word blau, an obsolete word for blow, is derived from this action). The mixture is used to generate liquid or gaseous hydrocarbons and was developed by German chemists, Fischer and Tropsch. 

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Petroleum coke is in reality a hydrocarbon whose C/H ratio is very high it is usually higher than 20 and can attain 1000 after calcination. It is not, therefore, elementary carbon. 

Petroleum coke is an excellent fuel, and that is its main use, especially for the coke from fluid coking". There are some other markets that have to do with calcined coke electrodes for aluminum production or for all other electrolytic cells, carbons for electro-mechanical equipment, graphite, and pigments. 

The major portion of sait is found in residues as these streams serve as the bases for fuels, or as feeds for asphalt and petroleum coke production, the presence of salt in these products causes fouling of burners, the alteration of asphalt emulsions, and the deterioration of coke quality. Furthermore, calcium and magnesium chlorides begin to hydrolyze at 120°C. This hydrolysis occurs rapidly as the temperature increases (Figure 8.1) according to the reaction i. ... 

As a whole, a given crude is generally used to make products most of which have positive added values. This is particularly the case for motor fuels and specialty products. However, some of the products could have negative added values, as in the case of unavoidable products like heavy fuels and certain petroleum cokes. 

Naphthalene, anthracene, carbazole [86-74-8] phenol [108-95-2] and cresyUc acids are found in the tar. Phenol and cresyUc acids are useful as chemical and resin intermediates. The aromatic chemicals are useful in the manufacture of pharmaceuticals, dyes, fragrances, and pesticides. Various grades of pitch are made from residues of tar refining. Coal-tar pitch is used for roofing and road tar, and as a binder mixed with petroleum coke to produce anodes for the aluminum industry. 

In 1984, the Ube Ammonia Industry Co. began operating the largest Texaco coal gasification complex to date. This faciUty is located in Ube City, Japan, and has a rated gasification capacity of 1500 t/day of coal, and production capacity of 1000 t/day of ammonia. The plant has successfully gasified coals from Canada, AustraUa, South Africa, and China. At the present time the plant uses a mixture of petroleum coke and coal (43). 

The Ube plant consists of four complete trains of Texaco quench-type gasifiers. During normal operation, three gasifiers are on line and one is on standby. Each gasifier consumes 500 t/day of coal to generate syngas for 350 t/day of ammonia. Up to the middle of 1990 the Ube plant gasified 2.2 million t of coal and petroleum coke. 

Heavy oil, ie, grade nos. 4, 5, and 6, and residual fuel oils light oils, ie, no. 2 heating oil, kerosene, and jet fuel and petroleum coke are deflvered at... 

Chloride Process. The flow chart of the chloride process is presented in Figure 4. In the chloride process, finely ground mtile reacts with chlorine in the presence of calcined petroleum coke. At a temperature between 800 and 1200°C, the following reaction occurs ... 

The barium sulfide needed for the reaction is prepared by the reduction of barite [13462-86-7] BaSO, with petroleum coke in a rotary furnace ... 

Piebaked anodes aie produced by molding petroleum coke and coal tar pitch binder into blocks typically 70 cm x 125 cm x 50 cm, and baking to 1000—1200°C. Petroleum coke is used because of its low impurity (ash) content. The more noble impurities, such as iron and siUcon, deposit in the aluminum whereas less noble ones such as calcium and magnesium, accumulate as fluorides in the bath. Coal-based coke could be used, but extensive and expensive prepurification would be required. Steel stubs seated in the anode using cast iron support the anodes (via anode rods) in the electrolyte and conduct electric current into the anodes (Fig. 3). Electrical resistivity of prebaked anodes ranges from 5-6 Hm anode current density ranges from 0.65 to 1.3 A/crn. ... 

Alternative Processes for Aluminum Production. In spite of its industrial dominance, the HaH-HAroult process has several inherent disadvantages. The most serious is the large capital investment requited resulting from the multiplicity of units (250 —1000 cells in a typical plant), the cost of the Bayer aluniina-puriftcation plant, and the cost of the carbon—anode plant (or paste plant for Soderberg anodes). Additionally, HaH-HAroult cells requite expensive electrical power rather than thermal energy, most producing countries must import alumina or bauxite, and petroleum coke for anodes is in limited supply. 

Includes petroleum coke, diesel, kerosene, petroleum sludge, and tar. 

Several utility-scale demonstration facilities having power outputs in the 300-MW class have been constmcted in the United States and Europe. These started accumulating operating experience in 1995 and 1996. Other IGCC plants have been constmcted, including units fueled by petroleum coke and refinery bottoms. Advanced 500-MW class IGCC plants based around the latest heavy-duty combustion turbines are expected to be priced competitively with new pulverized-coal-fined plants utilising scmbbers. 

Pitch. The principal outlet for coal-tar pitch is as the binder for the electrodes used in aluminum smelting. These are of two types. Older plants employ Sn derberg furnaces, which incorporate paste electrodes consisting of a mixture of about 70% graded petroleum coke or pitch coke and 30% of a medium-hard coke-oven pitch. This paste is added periodically to the top of the monolithic electrode as it is consumed. The more modem smelters employ prebaked electrodes requiring less binder, about 18%. 

Pitch Coke. The manufacture of pitch coke provides a large toimage oudet for coke-oven pitch in Japan, the CIS and, until more recently, Germany (75,76). Pitch coke is used either alone or mixed with petroleum coke as the carbon component of electrodes, carbon bmshes, and shaped carbon and graphite articles. 

Property Modifiers. Property modifiers can, in general, be divided into two classes nonabrasive and abrasive, and the nonabrasive modifiers can be further classified as high friction or low friction. The most frequently used nonabrasive modifier is a cured resinous friction dust derived from cashew nutshell Hquid (see Nuts). Ground mbber is used in particle sizes similar to or slightly coarser than those of the cashew friction dusts for noise, wear, and abrasion control. Carbon black (qv), petroleum coke flour, natural and synthetic graphite, or other carbonaceous materials (see Carbon) are used to control the friction and improve wear, when abrasives are used, or to reduce noise. The above mentioned modifiers are primarily used in organic and semimetallic materials, except for graphite which is used in all friction materials. 

Thermal Cracking. Heavy petroleum fractions such as resid are thermally cracked in delayed cokers or flexicokers (44,56,57). The main products from the process are petroleum coke and off-gas which contain light olefins and butylenes. This stream also contains a considerable amount of butane. Process conditions for the flexicoker are more severe than for the delayed coker, about 550°C versus 450°C. Both are operated at low pressures, around 300—600 kPa (43—87 psi). Flexicokers produce much more linear butenes, particularly 2-butene, than delayed cokers and about half the amount of isobutylene (Table 7). This is attributed to high severity of operation for the flexicoker (43). 

Ca.rhothermic Reduction. Sihcon carbide is commercially produced by the electrochemical reaction of high grade siUca sand (quartz) and carbon in an electric resistance furnace. The carbon is in the form of petroleum coke or anthracite coal. The overall reaction is... 

Graphitization. Graphitization is an electrical heat treatment of the product to ca 3000°C. The purpose of this step is to cause the carbon atoms in the petroleum coke filler and pitch coke binder to orient into the graphite lattice configuration. This ordering process produces graphite with intermetaHic properties that make it useful in many appHcations. 

The primary constituent is calciaed petroleum coke particles. 

Production of one metric ton of molten aluminum requites about 500 kg of anode carbon and 7.5—10 kg of cathode blocks which is the largest industry usage of carbon materials. Aluminum smelters generally have an on-site carbon plant for anode production. Anode technology is focused on taw materials (petroleum coke and coal-tar pitch), processing techniques, and todding practices (74). 

Carbon black from oil is the main competition for the product from coal, which is used in filters. Carbon for electrodes is primarily made from petroleum coke, although pitch coke is used in Germany for this product. The pitch binder used for electrodes and other carbon products is almost always a selected coal tar pitch. 

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