Petroleum coke from delayed coking

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). 

Coke produced from delayed coking is described as delayed sponge, shot, or needle coke depending on its physical structure. Shot coke is the most common when running the unit under severe conditions with sour crude residues. Needle coke is produced from selected aromatic feedstocks. Sponge coke is more porous and has a high surface area. The properties and markets for petroleum cokes have been reviewed by Dymond. Table 3-4 shows the types of petroleum cokes and their uses. ... 

Pitch Coke and Petroleum Coke Pitch coke is made from coal-tar pitch, and petroleum coke is made from petroleum residues from petroleum refining. Pitch coke has about 1.0 percent volatile matter, 1.0 percent ash, and less than 0.5 percent sulfur on the as-received basis. There are two kinds of petroleum coke delayed coke and fluid coke. Delayed coke is produced by heating a gas oil or heavier feedstock to... 

As a follow-up to this work. Walker and Baumbach (148) investigated the effect of heat treatment on the reactivities of carbons produced from 20 different coal tar pitches and one delayed petroleum coke. Heat treatment again produced a marked increase in crystallite size, a marked decrease in impurity content, and only a minor change in surface area. They use the... 

Fig. 29. Effect of heat treatment on the reactivity of carbons derived from coal tar pitch and delayed petroleum coke. Reaction with carbon dioxide at 1150°. [After P. L. Walker, Jr., and D. O. Baumbach, unpublished results 1969.]...

During the past 25 years United States petroleum coke production has increased from less than 1,000,-000 tons per year to 3,400,000. Most of the 1,000,-000 tons were produced in externally fired shell stills and manually removed from the stills. Almost all of the 3,400,000 tons were produced in large "delayed coker" type coke drums and removed mechanically. As was true 25 years ago, the major use for petroleum coke is as a fuel, although the proportion so used is declining. Its use in aluminum production is growing rapidly and currently takes about 18% of the production. 

This particular partial oxidation technique has also been applied to a whole range of liquid feedstocks for hydrogen production (Table 10-2) (Pelofsky, 1977). There is now serious consideration being given to hydrogen production by the partial oxidation of solid feedstocks such as petroleum coke (from both delayed and fluid-bed reactors), lignite, and coal, as well as petroleum residua. 

Since fhey confain fhe impurities from original crude oil, fhe sulfur is usually high and appreciable vanadium sails may be presented. Some main characteristics of fhe fwo fypes of petroleum coke are shown in Table 31.6. Table 31.7 summarize the main chemical and physical properties of fhe green delayed pefroleum coke in terms of ultimate and proximate analyses, inferior calorific value, free swelling index, HGI, and ash fusion femperafure. 

Formation of C8K from Calcined Petroleum Coke. Materials that are less crystalline than metaanthracite do form intercalation compounds. Calcined petroleum cokes are formed by thermolysis at approximately 1400 °C of green petroleum cokes, which in turn are made by thermolysis of aromatic petroleum streams in delayed cokers operating in the range of 400-500 °C (29-32). (Immature cokes of higher H/C ratio are termed green they are not green in color.) The crystallite size, measured both in the direction of aromatic stacking (c axis) and in the in-plane direction (a axis) is of the order 50-60 A, which is less than half the crystallite size of the metaanthracite. However, literature reports indicate that such materials do form intercalation compounds with potassium metal (33, 34). 

Surficial deterioration of alite, amoeboid ragged belite, dendritic and lake periclase, loss of alumina brick Overturning from delayed petroleum coke, producing longer burning zone (Jefferson and Kruse, 1987)... 

The sponge-type regular coke from the delayed coking of petroleum residues (petroleum coke) and coal-tar pitch (pitch coke), along with pitch coke from the horizontal-chamber coking process, are principally used in the manufacture of anodes for the aluminum industry (see Chapter 13.1.3). 

Delayed Coking A continuous process for increasing the yield of petroleum distillates from petroleum and also generating saleable coke, by thermal cracking of the distillation residues ( residuum ) in a complex... 

Delayed coking. Semi-continuous thermal cracking process used in petroleum refineries to upgrade and convert bottoms from atmospheric and vacuum distillation of crude oil into liquid and gas product streams, leaving behind a solid concentrated carbon material, petroleum coke, whose value will depend on its properties such as sulfur, metals, etc. The products of a delayed coker are wet gas, naphtha, light and heavy gas oils, and coke. The coke produced in the delayed coker is almost pure carbon and is utilized as fuel or, depending upon its quality, in the manufacture of anodes and electrodes (Hamilton, 2002 Elliott, 2003 Haniford, 2003 Elliott and Wedlake, 2007). 

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