JPS5932511B2 - Hydrogenation method for high-boiling hydrocarbons - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to hydrogenation processes, and in particular to processes for hydrogenating high boiling hydrocarbon materials to produce valuable low boiling materials.

High-boiling hydrocarbon materials derived from petroleum or coal feedstocks, typically petroleum bottoms or solvent-refined coal, are hydrogenated in a boiling (expanding) catalyst bed to produce further valuable low-boiling materials. .

The conversion rate of such operations is generally limited by the tendency of the catalyst to form heavy carbonaceous deposits which cause agglomeration.

This limit is a varying amount of conversion for each feedstock.

As a result, there is a need to improve such hydrogenation processes in order to enable them to operate at high conversions.

According to the invention, an improvement in a process for upgrading high-boiling hydrocarbon materials to valuable low-boiling materials in a hydrogenation operation comprising at least two ebulated bed hydrogenation zones in series is provided. wherein recycle material is recovered from the upgraded product such that at least 25% by volume of the recycle material consists of the 950'F+ component of the product.

The recycle material is contacted with a solid adsorbent to remove the coke precursor therefrom and the recycle material is fed to at least the end of the at least two hydrogenation zones.

The inventors have found that by feeding recycle material in this manner, the operational range of the hydrogenation reaction zone can be expanded, thereby allowing operation at high conversions.

The solid adsorbent used to remove coke precursor from recycled material is 1-200m/? It has the surface area of a pedestal.

Representative examples of suitable adsorbents include activated alumina,
Examples include bauxite, calcined coke, etc.
Calcined coke is preferred.

Generally, calcined coke has a surface area on the order of 1-5 m''/g.

Coke precursor adsorption is generally at least 400
°F, generally not exceeding 700'F, preferably not exceeding 600'F.

Adsorption is generally carried out at a temperature above the bubble point pressure of the recycle material, which pressure is below the pressure used for hydrogenation.

As mentioned above, at least 25% by volume of the recycled material is 9
Boils above 50'F.

In most cases, the 5% by volume distillation temperature of the recycled material is at least 4500F, preferably at least 550'F.
and most preferably at least 600 or less.

Conveniently, the recycled material is obtained by recovery from the product of the 550'F+ cut.

However, the recycle material has a higher boiling point, e.g.
00°F + distillate (5% by volume distillation temperature is at least 600°F)
°F, at least 25% by volume boils above 950'F), or 1000°F+distillate (5% by volume distillation temperature is at least 1000'F).

The recycled material is in the form of a liquid phase in the last hydrogenation zone.
Feed as high boiling recycle material to minimize the ratio of ~500 bottom distillate to 1000 bottom bottom.

Recycled material, after being treated to remove coke precursors as described above, is fed to at least the last of the two hydrogenation zones.

Recycled material can be fed to the last zone by introducing it directly into the adult zone, or all or part of it can be introduced into the previous zone, thereby providing recycled material to the last zone. It is also possible to supply all or part of the effluent from the preceding zone in series.

Upgrading of high boiling hydrocarbon materials by hydrogenation in two or more expanding non-catalytic hydrogenation zones is generally carried out catalytically at temperatures and pressures as known to those skilled in the art.

However, by practicing in accordance with the present invention, it is possible to operate at higher conversion rates than conventionally used in the art without adversely affecting overall operation.

Generally the hydrogenation is carried out at a temperature on the order of about 650 to about 900°F, preferably from about 750 to about 850°F, from about 500 to about 4
At an operating pressure of 1,000 psig, the hydrogen partial pressure is typically about 500 psig.
-3000 ps+a.

The catalyst used can be any one of a wide variety of catalysts for the hydrogenation of heavy materials, representative examples of such catalysts being cobalt molybdate, nickel molybdate, cobalt-nickel molybdate. Such catalysts, which may include acid salts, tungsten-nickel sulfide, tungsten sulfide, etc., are generally supported on a suitable support such as alumina or silica-alumina.

Such catalysts are maintained in the hydrogenation reactor as expanded or boiling beds as known to those skilled in the art.

The recycled material provided by the present invention has a ratio of recycled material to total fresh feedstock (to hydrogenation) of about 0.2:1 to about 1.
0:1, preferably from about 0.4:1 to about 1.0:1.

Each hydrogenation zone may or may not contain internal recycle material depending on the total flow rate to that zone.

If any, the amount of internally recycled material is adjusted by the amount of externally recycled material provided by the present invention.

The feedstock to this process is one that has high boiling components to be converted to more valuable lower boiling components.

Typically such hydrocarbon feedstocks will have at least 25% by volume of materials that boil above 950°F.

Such feedstocks are derived from petroleum and/or coal sources; generally the feedstock is petroleum, such as atmospheric column bottoms, vacuum column bottoms, heavy crude oil, or tar containing small amounts of materials boiling below 650'F. This is residual liquid or solvent-refined coal.

Preferred specific examples of the present invention shown in the drawings will be further explained.

Referring to FIG. 1, the hydrocarbon feedstock to be upgraded in line 10 is combined with recycled material in line 11 if used as described below.

The combined streams in line 12 pass through heater 13 where the combined streams are heated to a suitable hydrogenation inlet temperature, such as a temperature on the order of 600-800'F.

The heated hydrocarbon feedstock in line 14 is in line 1
5 and the combined stream in line 16 is introduced into the bottom of the first of two boiling rice hydrogenation reactors 17 and 18.

Reactors 17 and 18 are of a type known to those skilled in the art, with sufficient internal recycle within the reactors to maintain flow to provide boiling or expanding catalyst in reactors 17 and 18. A pump was installed at the bottom to provide circulating material (
(not shown) may include means 21 in the form of an internal tube.

If the flow of fresh feed and recycle material is sufficient to maintain the expanded catalyst bed, then the internal recycle material pipes and pumps can be omitted.

Reactor 17 operates as is well known to those skilled in the art and at temperatures and pressures as described above.

For example, the feedstock is passed upwardly through reactor 17 where it is contacted with a hydrogenation catalyst.

The effluent is then removed from reactor 17 via line 22 and introduced into second reactor 18.

The effluent in line 22 may be combined with recycle material from line 23, as detailed below, where the recycle material serves to cool the reaction effluent prior to hydrogen quenching.

Alternatively, as discussed below, recycle material may be supplied by line 24 following hydrogen quenching.

The effluent, which may or may not contain recycled material, is then quenched with hydrogen-containing gas in line 25, and the mixed stream in line 26 is then subjected to a second boiling unhydrogenation reaction. Introduce it to the bottom of the vessel 18.

Hydrogenation reactor 18 operates under conditions as described above to hydrogenate the feedstock and upgrade it to lower boiling point components.

As specifically indicated, the reactor 18 is fed with internal recycle material; however, as previously discussed, the internal recycle material is
It can be omitted when the total flow is sufficient to sustain the expanded catalyst bed.

The reaction effluent removed from reactor 18 by line 28 is introduced into gas separation zone 29 for recovery of hydrogen recycle gas from the effluent.

Gas separation zone 29 may include one or more gas-liquid separators and coolers for separation and recovery of hydrogen recycle gas.

Hydrogen recycle gas is recovered in line 31, suitably purged and compressed (not shown) and after addition of make-up hydrogen in line 32, a portion of the hydrogen is fed to reactor 18 via line 25 and a portion is is heated by a heater 33 and then supplied to the reactor 17 via a line 15.

Liquid product from gas separation zone 29 in line 35 is introduced into product separation and recovery zone 36.

Separation and recovery zone 36 may include one or more fractionators and/or separators designed and operated to recover various products and recycle streams from the hydrogenation effluent.

In particular, in accordance with the present invention, a liquid recycle stream is recovered in line 37 having the characteristics described above, i.e., having a 5% by volume distillation temperature of at least 450'F, at least 25% by volume of which has a boiling point above 950'F. do.

Preferably, the recycle material is the 550,000 or 1000° F. fraction recovered from the product.

Recycled material in line 37 is introduced into adsorption zone 38;
The recycled material is then contacted with an adsorbent, preferably calcined coke, to adsorb the coke precursor as described above.

Recycled material from adsorption zone 38 is routed to line 11 and/or 23 to provide recycle material to final reactor 18.
and/or used in 24.

All or part of the recycled material to reactor 18 may therefore be fed directly to reactor 18 or indirectly via reactor 17.

Although this embodiment has been specifically described with reference to the use of two hydrogenation reactors, it should be understood that more than two reactors may be used.

In such a case, the last reactor may be fed with recycled material as described above, such recycled material may be fed directly to the last reactor, or one or more of the preceding reactors may be fed with recycled material. It may also be supplied indirectly by

According to the invention, external recycle material is fed to the last reactor in the series of reactors, such recycle material is pretreated to remove coke precursor, and in the liquid phase of the last reactor, It has boiling point characteristics to minimize the ratio of 300-500°F distillate to under 1000 residue.

The present invention will be explained below with reference to Examples.

The following example shows conditions for the hydrogenation of a prefixed crude oil using three expanded bed reactors in series.

The catalyst was nickel molybdate supported on alumina.

The recirculated material is calcined coke (6~
There was one bottom fraction of 550 ml recovered from the hydrogenation product which was contacted with 20 mesh, bulk density 431 b/ft3).

The recycle material was then heated to 650'F and introduced into the second and third reactors at a ratio of 2:1 to 10:1 of combined recycle material to total fresh feed.

The present invention is particularly advantageous in that for a given feedstock, the range of conversion rates that can be manipulated is expanded.

For example, by operating in accordance with the present invention, high conversion rates can be used without the difficulties hitherto encountered in this art.

The invention therefore allows the hydrogenation of heavy hydrocarbon feedstocks to be carried out at high conversion rates without increased pressure drop or difficulty in controlling the reaction temperature.

[Brief explanation of drawings]

FIG. 1 is a process diagram of a specific example of the present invention.

Claims (1)

[Claims] 1. A method for upgrading a high-boiling hydrocarbon material to a low-boiling material that has value in a hydrogenation operation comprising at least two expanded uncontacted hydrogenation zones in series to produce an improved hydrogenation product, comprising: 5% by volume distillation temperature of at least 450°F from the upgraded hydrogenation product, and at least 25% by volume thereof is 950°F.
The recycle material having a boiling point above F is recovered, the recycle material is contacted with a solid adsorbent having a surface area of 1 to 200 m/9 to remove the coke precursor therefrom, and the recycle material is passed through two hydrogenation zones. A method characterized by introducing at least at the end of.