FR2503732A1 - Hydrocracking of heavy oils esp. tar-sand bitumen - in form of slurry contg. coal - Google Patents

Abstract

Hydrocracking of heavy hydrocarbon oils contg. a large amt. (usually more than 50 wt.%) of material boiling above 524 deg.C is carried out by (a) passing a slurry comprising 2-50 wt.% coal in the feed oil through a hydrocracking zone at 400-500 deg.C and more than 200 psig, with a LHSV of 0.5-4.0, in the presence of 500-50,000 scf of H2 per bbl of oil; and (b) sepg. the effluent into a gas stream contg. H2 and hydrocarbon vapours and a liq. stream contg. heavy hydrocarbons. The process is esp. applicable to tar-sand bitumen. The bitumen acts as an H-donor solvent for liquefying the coal and the ash content of the coal acts as a catalyst promoting hydrocracking and desulphurisation of the bitumen and suppressing coke deposition in the reactor.

Description

 The invention relates to hydrocracking and, more particularly, to the simultaneous hydrocracking of coal and a heavy hydrocarbon oil, such as bitumen from asphalt sands.

 Hydrocracking processes are well known for transforming heavy hydrocarbon oils into light and intermediate naphthas of good quality, in order to obtain a reforming charge, fuel oil and gas oil. These heavy hydrocarbon oils can be substances such as crude petroleum, atmospheric or vacuum residues of (n, schste oil nsyiXes, fluids derived from cbarboei, crude petroleum residues, headless crudes and heavy oils bituminous oils extracted from asphalt sands. Particularly interesting are oils extracted from asphalt sands, which contain substances with a wide boiling range, ranging from naphthas to kerosene, gas oil, pitch, etc., and which contain a large proportion, usually greater than 5096 by weight, of substances with a boiling point greater than 5240C, equivalent boiling point under atmospheric pressure.

 Heavy hydrocarbon oils of the above type tend to contain nitro and sulfur compounds in very large concentrations. In addition, these heavy hydrocarbon fractions often contain excessive amounts of polluting organometallic compounds, which tend to be extremely harmful to various catalytic processes which can be carried out thereafter, such as catalytic hydrogenation. Among the metallic pollutants, those containing nickel and vanadium are the most common, although other metals can often be present. These and other metallic pollutants are presently present in the bituminous substance in the form of organometallic compounds of relatively high molecular weight. A considerable amount of the organometallic complexes is attached to the asphaltene substance and contains sulfur. Of course, when a catalytic hydrocracking is carried out, the presence of large quantities of asphaltenic substance and of organometallic compounds considerably hinders the activity of the catalyst with regard to the elimination by destruction of the nitrogenous, sulfurous and oxygenated compounds. A typical Athabasca bitumen may contain 53.76% by weight of substance boiling above 524QC, 4.74% by weight of sulfur, 0.59% by weight of nitrogen, 162 parts of vanadium per million and 72 parts of nickel per million.

 As conventional crude oil reserves decrease, these heavy oils need to be upgraded to meet demand. During this improvement, the heavier substance is transformed into lighter fractions and most of the sulfur, nitrogen and metals have to be removed. This is usually done by a coking process, such as delayed or fluidized coking, or by a hydrogen addition process, such as thermal or catalytic hydrocracking. The distillation yield, by the coking process , is about 70% and this process also provides about 23% by weight of coke as a by-product, which cannot be used as fuel due to the low hydrogen to carbon ratio, and the high content of mineral product and sulfur. Depending on the operating conditions, the hydrogenation processes can give a distillation yield greater than 87% by weight.

Canadian Patent 1,073,389 and the United States Patent
United States of America 4,214,977, addition of carbon or a carbon-based catalyst has been shown to decrease the deposition of coke during hydrocracking and generally improve operation.

The added carbon serves as an "absorbent" for coke deposits and prevents any accumulation of coke.

It is also possible that the coal mineral acts as a catalyst to prevent the formation of coke.

In these prior processes, only secondary attention is paid to the hydrogenation of carbon.

In the hydrocracking of coal, the hydrogen: coal process involves the suspension of coal in an oil derived from coal and the subsequent reaction on hydrogen at high temperatures and at high pressures in the presence of a Co-Mo / alumina catalyst. Other processes for transforming carbon, such as the SRC process (refined solvent carbon), EDS (Exxon donor solvent) and the Synthoil process also recycle distilled fractions from coal as solvents. These processes are described for example by Richardson, FW "Oil From Coal",
Noyes Data Corporation, Parkridge, New Jersey, 1975, page 386.

 Not only bitumen, but coal also contains heavy asphaltenes and mineral matter which quickly poison the catalyst. This results in excessive consumption of the catalyst and high operating costs. Both for the bitumen improvement process and for the coal improvement process, the fixed bed catalytic processes are not economical due to bed blockages which lead to costly downtime. A boiling catalyst bed is best suited for hydrocracking bitumen or coal. Both the hydrogen: coal process and the hydrogen-oil process use this operating mode. In the boiling bed, the upward passage of liquid and gaseous materials keeps the catalyst in the fluidized state. Catalyst can be added and removed continuously to maintain constant activity. But the hydrogen: coal or hydrogen: oil process uses an expensive Co-Mo / alumina catalyst, which deactivates quickly at high conversions, which leads to excessive operating costs.

As has been demonstrated in the above-mentioned patents, the operating costs can be reduced by using cheap catalysts of the disposable type and this is the case, for example, in the patent of
United States of America 4,214,977, describes the use of a carbon-iron catalyst which allows operation at lower pressures and with higher conversions. The use of carbon and Co, Mo and Al catalysts on carbon is described in Canadian Patent 1,073,389.

 The invention aims to take advantage of the solvent and hydrogen-generating action of a bitumen charge as well as the catalytic action of a carbonaceous mineral material in order to obtain a new, more economical hydrocracking process.

The subject of the invention is therefore a process for hydrocracking a heavy hydrocarbon oil, a large portion of which has a boiling point above 5240C, which consists
a) passing a suspension of this heavy hydrocarbon oil and from 2 to 50% by weight approximately of coal in the presence of 14 to 1400 m3 of hydrogen per 0.16 m of the hydrocarbon oil in a zone of confined hydrocracking, maintained at a temperature between about 400 and 500 "C and at a pressure of at least 1.4
MPa, at a space velocity of between approximately 0.5 and 4 volumes of hydrocarbon oil per hour per volume of the capacity of the hydrocracking zone,
b) withdrawing from the hydrocracking zone a mixed effluent containing a gaseous phase comprising hydrogen and hydrocarbons in the form of vapor and a liquid phase comprising heavy hydrocarbons, and
c) to subdivide this effluent into a gaseous stream containing hydrogen and hydrocarbons in the form of vapor and into a liquid stream containing heavy hydrocarbons.

 This process provides simultaneous hydrocracking of the heavy oil and the carbon, the heavy oil serving as a good solvent vehicle and the carbon of the catalyst avoiding coke formation reactions.

 Although the process according to the invention is particularly suitable for the treatment of bitumen, it is also very well suited for the treatment of topped bitumen or pitch. it can be implemented at quite moderate pressures, for example between 1.4 and 24 MPa, without formation of coke in the hydrocracking zone.

 The hydrocracking process according to the invention can be carried out in a wide variety of known upward or downward reactors. Thus, the area of the hydrocracking reactor can be a non-lined tubular reactor, a boiling bed reactor or a fluidized bed reactor. The non-lined tubular reactor has proven particularly convenient when the effluent from the top is subdivided into a hot separator and when the gas stream from the hot separator is sent to a low pressure high temperature separator where it is subdivided into a gas stream containing hydrogen and lesser amounts of gaseous hydrocarbons and in a stream of produced liquid containing light oils produced. It is also possible to have reactors in stages, the first reactor being a tubular reactor not filled while the second contains a boiling bed of extruded catalytic products.

 Any type of coal, such as lignite, sub-bituminous, bitumen, etc., can be used as charcoal in the charge suspension. Coal can be used as it is without additive or it can be coated with up to about 10% by weight of metallic sex, such as iron, iron, cobalt, molybdenum, zinc , tin, tungsten, nickel or other catalytically active salts. The use of catalytic substances improves the conversion of coal and bitumen as well as the ability of the process to work, but the metallic charge must depend on the material costs, the acceptable ash content and the optimal activity of the catalyst.

 The catalyst can be applied to carbon by spraying carbon particles using the aqueous solution of the metal salt. The carbon is then dried to reduce the moisture content before mixing it with the load.

 The particles of carbon used must be quite small, for example less than 0.25 mm.

The coal must be mixed with the bitumen so as to avoid any formation of aggregates and if necessary, homogeneous or heterogeneous catalysts can be added to the suspension of coal and bitumen.

 The simultaneous hydrogenation process produces pitch which contains asphaltenes, ash and residues of both bitumen and coal. Depending on the type of coal used and the charge used, the properties of the pitch vary. For example, low-sulfur sub-bituminous coals from Western Canada produce low-sulfur pitch. This decreases the cost of purifying the stack gases, while increasing the ash content of the pitch.

 The presence of large amounts of carbon in the suspension, as mentioned above, suppresses the formation of coke during hydrocracking. The result is that the hydrocracking of coal and bitumen can be carried out simultaneously under very low pressures. However, in certain situations, it is desirable to operate at higher pressures so as to maximize the liquid yields as well as the quality of the product.

 According to a preferred variant, the bitumen and the coal are mixed in a loading tank and they are sent by pumping along with hydrogen, in an vertical tube reactor which is not packed. The liquid-gas mixture from the top of the hydrocracking zone is subdivided in a hot separator maintained at a temperature of between 200 and 4700C approximately and at the pressure of the hydrocracking zone. The heavy hydrocarbon produced from the hot separator can be partially recycled to the hydrocracking zone or sent for secondary treatment.

 The gas stream from the hot separator containing a mixture of gaseous hydrocarbon and hydrogen is further cooled and subdivided into a low pressure high temperature separator. Using this type of separator, the output gas stream obtained contains most of the hydrogen with some impurities, such as hydrogen sulfide and light gaseous hydrocarbons. This gas stream is passed through a washer and the washed hydrogen is recycled as part of the hydrogen feed to the hydrocracking process. The purity of the recycled hydrogen gas is maintained by regulating the washing conditions and by adding a make-up of hydrogen.

 The liquid stream coming from the high pressure low temperature separator represents the light hydrocarbon produced by the process according to the invention and can be sent to a secondary treatment.

 Part of the coal can be entrained with the heavy oil produced from the hot separator and end up in the pitch fraction whose boiling point is above 5240C. We can burn this coal or gasify it with pitch.

 The single figure of the accompanying drawing is a diagram illustrating a preferred embodiment of the method according to the invention.

 In a loading tank 10, a load of heavy hydrocarbon oil and coal is mixed to obtain a suspension. This suspension is pumped out using a pump II and an inlet conduit 12 at the bottom of an unsupported tower 13. At the same time, recycled hydrogen and make-up hydrogen from a conduit 30 are sent to the tower 13 via the conduit 12. A gas-liquid mixture is drawn from the top of the tower via a conduit 14. is introduced into a separator 15 hot. In the hot separator, the effluent from tower 13 is subdivided into a gas stream 18 and a liquid stream 16. The liquid stream 16 is in the form of a heavy oil which is collected at 17.

 The hydrogen-rich stream 22 is sent to a washing tower 23 which is washed with a washing liquid 24 which is recycled in the tower using a pump 25 and a recycling loop 26. The washed hydrogen-rich stream leaves the washer through a line 27 and is supplied with fresh make-up hydrogen, added through a line 28 and recycled by a pump 29 for the recycled gas and a line 30 going to the tower 13 .

 The following examples illustrate the invention.

Example 1
Sub-bituminous coal is obtained from the White Wood coal mine and has the following properties
Calorific value *, kJ / kg 25,900
Carbon *, weight percentage 67.1
Hydrogen *, percentage by weight 4.0
Sulfur *, weight percentage 0.2
Nitrogen *, weight percentage 0.9
Ash *, weight percentage 9.5
Oxygen, percentage by weight
(by difference) 18.3
Humidity (as received),
weight percentage 9.6
Insoluble in pentane,
weight percentage 94.8
Insoluble in toluene,
weight percentage 91.6
* Properties of carbon in dry matter.

 The above carbon is ground and sieved in order to obtain a substance whose particle size is less than 0.250 mm.

The bitumen used is an Athabasca bitumen having the following properties
Density, 15 / 150C 1.013
Sulfur, weight percentage 4.74
Nitrogen, weight percentage 0.59
Ash, percentage by weight 0.59
Viscosity at 990C, cst 213
Conradson carbon residue,
weight percentage 14.9
Insoluble in pentane
percentage by weight 16.8
Insoluble in benzene,
weight percentage 0.52
Nickel, part per million
(by weight) 72
Vanadium, part per million
(by weight) 162
Pitch content, percentage in
weight 53.75
Sulfur in the part that says
tille below 5240C,
weight percentage 2.96
Sulfur in the pitch which distills
above 5240C, percentage
by weight 6.18
A mixed suspension of bitumen and 10% by weight of coal is prepared and this suspension is used as feed for a pilot hydrocracking installation. The pilot installation uses the reaction sequence illustrated in the accompanying drawing and operates under the conditions following reaction
Reaction pressure 13.8 MPa
Reactor temperature, OC 460
Loading rate, g / h 9000
Gas flow, m3 / h 5.5
Hydrogen concentration
in percent by volume 85.0
Separator temperature at
hot, in OC 370
The results obtained in this test are as follows
Pitch conversion * (boiling above 5240C) percentage by weight 74.85
Sulfur conversion, percentage by weight 45.3
Hydrogen consumed, m3 / 0.16 m3 22.2
Product volume yield in percentage by volume 97.6
Weight yield in product in percentage by weight 90.9
Product density, 15 / 150C 0.943
Sulfur in what distills below 5240C, weight percentage 2.33
Pitch in the product, percentage by weight 16.16
Ash in the pitch produced, percentage by weight 11.0
Sulfur in pitch, weight percentage 3.43 * Includes coal based on the determination of the
load pitch, including coal; and the product
including coal.

Example 2
The above hydrocracking process is repeated under identical conditions, but without adding coal to the bitumen feed. The results obtained are as follows
Pitch conversion (boiling above 5240C), percentage by weight 76.1
Sulfur conversion, percentage by weight 45.4
Hydrogen consumed, m3 / 0.16 m3 23.9
Product density, 15 / 150C 0.928
Sulfur in the distilling part, below 5240C, percentage by weight 2.54
Sulfur in pitch, percentage by weight 5.12
It appears from the above examples that the conversion of pitch in the presence of carbon compares very favorably to that in the process without carbon. The degree of sulfur removal is also similar. The most important difference is the sulfur content of the pitch.

 Based on the balance for sulfur and products insoluble in pentane, it was found that almost 5096 of the coal was transformed into liquid or gaseous products. Based on the carbon content of the coal as received (60.7% by weight), the conversion to liquids is about 82% of the possible conversion of the coal and based on the estimate that only 50% of the added coal remains in the pitch produced, the conversion of the bitumen-pitch fraction is of the order of 82%. This indicates that the presence of carbon significantly increases the liquid yield, which gives a more efficient process with the advantage of a pitch having a lower sulfur content. The conversion of carbon and the qualities of liquid products can be modified by modifying the catalytically active metal salts or the type of carbon used.

Claims (9)

 1) Hydrocracking process for a heavy hydrocarbon oil, a large proportion of which has a boiling point above 5240C, which consists in passing a charge of heavy hydrocarbon oil in the presence of 14 to 1400 m3 of hydrogen 0.16 m3 of hydrocarbon oil in a confined hydrocracking zone, maintained at a temperature between 400 and 5000C approximately and under a pressure greater than 1.4 MPa, at a space speed between approximately 0.5 and 4 , 0 volumes of heavy hydrocarbon oil per hour per volume of capacity of the hydrocracking zone, characterized in that it consists in mixing 2 to 50% by weight of coal with the charge of heavy hydrocarbon oil and in hydrocracking the charge of oil and coal simultaneously in the hydrocracking zone, to draw off a mixed effluent containing a gas phase comprising hydrogen and hydrocarbons in the form of vapor and a liquid phase comprising heavy hydrocarbons from the zone hydrocracking and subdividing this effluent into a gaseous stream containing hydrogen and hydrocarbons in the form of vapor and into a liquid stream containing heavy hydrocarbons. 2) Method according to claim 1, characterized in that the coal has a particle size less than 0.250 mm. 3) Process according to claim 1 or 2, characterized in that the coal is a sub-bituminous coal, a bituminous coal or a lignite. 4) Method according to one of claims 1 to 3, characterized in that it consists in raising the charge suspension in a tubular reactor. 5) Method according to one of claims 1 to 4, characterized in that it consists in coating the carbon with up to 10% by weight of a metal salt forming catalyst. 6) Method according to claim 5, characterized in that the metal salt is an iron salt, a cobalt salt, a molybdenum salt, a zinc salt, a tin salt, a nickel salt or a salt of tungsten. 7) Method according to one of claims 1 to 6, characterized in that it consists in carrying out hydrocracking under a pressure between 1.4 and 24 MPa. 8) Method according to one of claims 1 to 7, characterized in that it consists in subdividing the mixed effluent in a hot separator. 9) Method according to claim 8, characterized in that it consists in cooling and subdividing the gas stream from the hot separator in a low temperature separator into a gas stream containing hydrogen and lesser amounts of hydrocarbons gaseous and in a stream of produced liquid containing produced light oils.