Coker Gas Oil Research Articles

Sulphur-containing polynuclear aromatic hydrocarbons from petroleum : Examination of their possible statistical formation in sediments

Two procedures are described for the determination of sulphur-containing polynuclear aromatic hydrocarbons (SPAHs) in petroleum and in its derived industrial products. As a general clean-up procedure, the total aromatic fractions were obtained after partition of the sample between dimethyl sulphoxide (DMSO) and pentane, followed by liquid—liquid extraction of the DMSO layer. In the first method, SPAHs were oxidized to sulphones, isolated selectively and back-reduced to SPAHs. The second approach was the direct determination of SPAHs in the aromatic fractions from the clean-up, by gas chromatography with selective detection using a flame photometric detector and gas chromatography—mass spectrometry with selected ion monitoring. The determination of SPAHs in four crude oils and a coker gas oil is reported. The various isomers are assumed to have been formed in sediments by random alkylation and degradation mechanisms, although specific substances with an increased stability compared with that of other isomers accumulated preferentially. For dibenzothiophene congeners, the number of GC peaks observed in a capillary column chromatogram is close to the maximum number of peaks that could be observed, as predicted by the statistical theory of Giddings. For benzothiophene congeners, the observed number is smaller. SPAHs are concluded to result from severe transformation mechanisms of the organic precursors occurring in sediments.

Comparative Hydrodesulfurization of Athabasca Oil Sands Coker Gas Oil Over Ni‐Mo and Co‐Mo Catalysts

AbstractThe hydrodesulfurization of Athabasca oil sands coker gas oil has been compared over Ni‐Mo and Co‐Mo catalysts on the basis of rate constants at 400°C, 10.3 MPa (H2) and at an LHSV of 12.0 h−1. Both catalysts were cylindrical extrudates of 3.5 mm × 1.6 mm. A Berty Continuous Stirred Tank Reactor (CSTR) was used for the hydroprocessing. Although the Ni‐Mo catalyst had higher activity per gram of catalyst, on the basis of the rate constant per gram of molybdenum, the Co‐Mo catalyst was slightly more active with lower activation energy than the Ni‐Mo catalyst for HDS.

Identification of carbazole derivatives in a hydrotreated coker gas oil by gas chromatography and gas chromatography—mass spectrometry

Non-basic nitrogen-containing polyaromatic hydrocarbons (NPAHs) were determined in a hydrotreated coker gas oil using gas chromatography and combined gas chromatography—mass spectrometry. The abundant NPAHs are alkylated benzologues of carbazole. The relative distribution of the carbazole derivatives in the sample is characterized by the presence of alkylcarbazoles with up to four carbon atoms in the substituents and alkylbenzocarbazoles branched by chains with two carbon atoms or less. Substances with polymethyl structures are the most abundant. Although severe hydrotreating conditions were applied to the feedstock, the observed NPAHs could not be eliminated. Their resistance is probably a function of the position of the alkyl groups on the aromatic nuclei.

Catalytic cracking of light coker gasoil

Results are presented from experiments on the catalytic cracking of light gas-oil produced by delayed coking of a low-sulfur vacuum resid. A proposal is given for the utilization of these products. The physicochemical properties of the light gas-oil are analyzed. Results of the study show that cat cracking of vacuum gas-oil together with light coker gasoil in a two-stage unit gives substantial increases in the resources of cat cracker feed--in the capacity of the unit, and in the output of light products.

Catalytic cracking of heavy coker gasoil

In delayed coking units, considerable amounts of heavy gasoil are produced along with the electrode coke. Because of the predicted increase in totalinstalled capacity in delayed coking units, the total amounts of heavy gasoil available will be considerably greater. In almost all delayed coking units, heavy gasoil is a byproduct; and in most cases, it is worked off as boiler fuel. However, various approaches are being examined for better utilization of this material [1-6].

Identification of carbazoles and benzocarbazoles in a coker gas oil and influence of catalytic hydrotreatment on their distribution

Fractions highly enriched in pyrrole benzologues have been extracted from a coker gas oil before and after hydrotreatment under selected operating conditions. Carbazole, methyl- and dimethylcarbazoles and benzocarbazoles have been identified by means of g.c. coelutions with standards. The study of these compounds after catalytic hydrotreatment has shown that benzocarbazoles are more effectively removed than carbazoles in highly hydrogenating conditions (partial pressure of hydrogen, 10 MPa; temperature, 360 °C) whereas alkyl carbazoles and more particularly 1-methyl derivatives are more altered at a high temperature (380 °C, partial pressure of hydrogen, 5 MPa).

Identification of nitrogen bases in a coker gas oil and influence of catalytic hydrotreat ment on their composition

The investigation of nitrogen bases occurring in a coker gas oil before and after catalytic hydrotreatment has shown important differences in reactivity of azaarenes. Compounds with a low degree of aromaticity are relatively resistant compared with higher benzologues. Particularly stable are α-methylated azaarenes, which are also major nitrogen bases found in crude oils. Alkyl anilines, the last intermediates before denitrogenation, are the most abundant bases in hydrotreated samples.

Selective isolation of nitrogen bases from petroleum

A method has been designed for the rapid separation of nitrogen bases from petroleum by trapping their quaternary ammonium salts on hydrochloric acid treated silica. A chromatographic column filled with this adsorbent and equipped with a solvent recycling system allows a selective and quantitative extraction of basic compounds from large amounts (>100 g) of crude oil. The procedure has been tested with reference compounds, a coker gas-oil, and a heavy biodegraded crude and applied to 15 different oil samples. 22 references, 3 figures, 4 tables.

Hydrodesulfurization of coker feed

This article presents data on the hydrodesulfurization of heavy coker gasoils, a distillate from the tar obtained in the thermal cracking of resid, heavy vacuum gasoil (350-520/sup 0/C), and blends of these stocks in various ratios. A single-pass flow unit was used with a fixed bed of commercial alumina-cobaltmolybdenum catalyst. Hydrodesulfurization of the gasoils was studied at temperatures of 360-400/sup 0/C, feedstock space velocities of 0.7-1.5h/sup -1/, a pressure of 5 MPa, and a hydrogen circulation ratio of 800 m/sup 3//m/sup 3/. The heavy gasoils obtained in destruction processes were hydrodesulfurized in blends with heavy vacuum gasoil (350-520/sup 0/C) in weight ratios of 70:30 and 50:50. It is determined that dilution with the heavy vacuum gasoil (350-520/sup 0/C) has very little effect on the conditions for hydrodesulfurization of a feedstock of secondary origin. The degree of hydrodesulfurization shows a slight increase only when the distillate from the cracked tar is diluted in a 50:50 weight ratio. When the coker gasoil is diluted with a light vacuum gasoil (350-478/sup 0/C), the same degree of desulfurization is achieved with a 70:30 dilution ratio and a hydrotreating temperature of 380/sup 0/C. The primary coke-forming components in the examined feedstocks are polycyclic aromatic hydrocarbonsmore » and resins. Includes 3 tables.« less

Effect of pressure on coke yield in delayed coking

This paper presents data on the effect of pressure, in a coking straight-run and secondary resids from West Siberian crudes, on the yield and quality of the coke that is obtained. Increasing the pressure has a very marked effect on the coke yield, increasing the gas yield, and reducing the relative amount of coker gas oil. Pressure also changes the hydrocarbon composition of the distillates, though it has no effect on the content of sulfur in the coke. In general, by increasing the pressure in delayed coking of various types of feeds, the coke yield can be increased.

Chemical composition of heavy coker gasoil and products from its adsorptive treatment

Chemical composition of heavy coker gasoil and products from its adsorptive treatment

Quality of marine boiler fuel obtained by the use of coker gas oil from samotlor crude

Quality of marine boiler fuel obtained by the use of coker gas oil from samotlor crude

Influence of pyrolysis process conditions on yield and quality of products obtained with coker gas oil as feedstock

Influence of pyrolysis process conditions on yield and quality of products obtained with coker gas oil as feedstock

Process mechanisms in coking a distillate feedstock

1. The coking mechanism for distillate feedstocks has been studied in the example of an extract from a coker gas oil. 2. In contrast to the coking of residual stocks, the coking of a distillated feedstock that is essentially asphaltene-free, within the limits of the process conditions investigated, brings about a continuous accumulation of asphaltenes in the residue. 3. Another difference observed with distillate feedstock is that the drop in oil quantity is considerably less. For this type of feedstock, the resins do not have any significant role in carboid formation, so that coke may be formed in accordance with the following scheme: polycyclic hydrocarbons→asphaltenes→coke.

Methods of decreasing the volatiles content of coke obtained by the delayed coking process

To obtain coke of minimum volatiles content and maximum mechanical strength by the delayed coking process, the following measures are necessary: 1) Preheating of the feed to a sufficiently high temperature so that its temperature at the reactor inlet will be not lower than 480°C. 2) Effecting “cementation” of the coke in the reactor by use of coker gas oil vapors or superheated steam at 500°C or higher, a “cementation” time of 3–5 h, and gas oil and gas oil vapor consumption rates of 20–25 and 3–5 tons/h, respectively, or a saturated steam consumption rate of 0.3–0.6 tons/h; 3) Adding 3.8 ppm (based on converted feed) of polymethyl siloxane (or polydimethylsiloxane) liquid over a 2–3 h period until all the feed has been supplied to the reactor.

Unicracking-JHC Process

Unicracking-JHC is a modern regenerative fixed-bed catalytic process for selectively converting high boiling hydrocarbons such as virgin, steam cracked and coker gas oils and catalytic cycle oils to lower boiling products-gasoline, jet fuel and diesel oils-with a net consumption of hydrogen. Various conversion levels are possible including total conversion to gasoline and lighter. With complete conversion, liquid yield of 120-130 volume percent of feed are common.Unicracking-JHC process utilizes a high activity catalyst which has excellent activity maintenance in the presence of nitrogen and sulfur compounds. Typical reaction temperatures are 500-800°F and operating pressures range from 800-2, 000 psi, exact conditions being fixed by feed stock propeties and processing objectives. Either singlestage or two-stage hydrocraking may be employed. The choice depends on feed rate, feedproperties, processing objectives. For most stocks, recent technological develop-ments permit economic conversion to gasoline and lighter products in a single stage.Eight Unicracking-JHC units totaling 90, 000 BPSD of capacity are now on stream, and other units under construction or announced will bring the total to about 200, 000 BPSD by the end of 1968.