FI59810B - FOER FRAMSTAELLNING AV BRAENSLE FOER JETMOTOR - Google Patents

Description

-tffo- r \ rRl «« ANNOUNCEMENT r Λ Λ. _ 4¾¾ L] (1) UTLÄQCNINGSSKRIFT 5 981 0 (^ 5) Pa tent r.,: J. j 1: i t '* ^ (51) K * jL3 / nta3 C 10 6 45/44 FINLAND — FINLAND (H) Putnttihtkemui - Patmtamekninf 2312/72. (22) Hak «nl» cloud - Anaeknln | * dag 21.08 * 72 * "(23) Alkupllvl —GIMgh« ttdtg 21.08.72 (41) Tullut kiikikuksi - Bllvlt off «ntll | 03.03-73

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Patent- och rtgiataratyralsan '' ArwOkan utltjd och utl. * Krift # n publlcarad 30.06.8l (32) (33) (31) Requested ttuolkuui —Bujird prlorttut 02.09 · 71 USA (US) 177362 (71) Hie Lummus Company, 1515 Broad Street, Bloomfield, New Jersey 07003, USA (72) Morgan Chuan-Yuan Wed, Upper Montclair, New Jersey, James William Reilly, Westfield, New Jersey, USA (7U) Berggren 0y Ab (5 ^) The present invention relates to the production of jet fuel from hydrocarbon feedstocks. In general, a large number of methods have been proposed for the production of jet fuel from a wide variety of feedstocks, in some processes different petroleum fractions or products are treated by hydrocracking, reforming, alkylation, etc. processes, in various combinations. U.S. Patent No. 3,513Ο85, which describes the preparation of jet fuel from hydrocarbons and petroleum by hydrocracking, solvent extraction, fractionation and hydrogenation, is typical of these processes. Other methods of producing jet fuel have used the hydration of aromatic feedstocks in various ways, sometimes in conjunction with other processes such as hydrocracking. For example, U.S. Patent No. 3,110,210 describes the preparation of jet fuel by catalytic hydrogenation of high boiling aromatic hydrocarbons, preceded by a "hydrofining" step. The sulfur compounds are removed from the feedstock downstream of the hydrogen added thereto, in a first step, the hydrogen sulfide is boiled off after the first step, and the liquid thus purified is subjected to catalytic hydrogenation countercurrently with hydrogen in a second step.

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Detailed quality requirements for various types of jet fuel have been published by the U.S. Defense Forces and ASTM. There are currently three jet fuel fuels in common use, marked JP- ^ 1, JP-5 and ASTM D-1655 Jet A-l fuel. As regards the most critical properties, the quality requirements include a maximum sulfur content of 2000 ppm (0.2%) by weight, an IPT smoke point of at least 25 mm and an aromatic content of no more than 20% by volume. In addition to methods such as those described in the previous paragraphs, attempts have also been made to use various fuel oil fractions directly as jet fuel. Although these fractions meet many quality requirements for jet fuel, they often do not meet the IPT smoke point requirement.

In addition, some Fire Oils contain more aromas than quality standards allow.

It is therefore an object of the present invention to provide a process for producing jet fuel from a hydrocarbon feedstock which does not require the use of expensive process steps such as hydrocracking.

The invention therefore relates to a process for the production of jet fuel by hydrogenating in two stages a hydrocarbon feedstock having a boiling range of about 150-290 ° C and substantially free of sulfur-containing impurities, and the process is characterized in that (a) the feedstock is passed in downstream contact with a hydrogen-rich gas through a first hydrogenation zone operating at a temperature of about 120-300 ° C and elevated pressure, in contact with a hydrogenation catalyst to at least partially hydrogenate the feedstock; (b) removing a gas phase effluent comprising hydrogen and vaporized liquids and a partially hydrogenated liquid phase hydrocarbon stream from the first hydrogenation zone; (c) hydrogenating said liquid phase hydrocarbon stream in a second hydrogenation zone operating at a temperature of about 90-260 ° C and elevated pressure, directing it to the second hydrogenation zone upstream of the hydrogen-rich gas, in contact with the hydrogenation catalyst; which contains hydrogen and vaporized liquids, and a liquid phase effluent which is jet fuel.

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Other objects and features of the invention will become apparent from the following description, the accompanying drawing and the claims.

The accompanying drawing is a schematic representation of the process according to the invention.

As can be seen from the drawing, the hydrogenation zones are preferably inside the same hydrogenation vessel, which is in the shape of a vertical cylinder and has convex ends and pressure-resistant walls. The interior of the vessel is divided into a plurality of chambers, i.e. zones, by a horizontal intermediate chamber 12, 14 and 24, preferably torn plates or the like, which are the upper reaction chamber 16, the central vapor separation chamber 20 and the lower reaction chamber 18. The reaction chambers 16 and 18 are filled with 22, which may be any known hydrogenation-dehydrogenation catalyst such as Raney nickel, or nickel, platinum or palladium, preferably with a support such as alumina, silica, diatomaceous earth, magnesium oxide, zirconia or other inorganic oxide. alone or in combination. The catalyst in zone 16 is supported by a midsole 12. The catalyst in zone 18 is supported by a similar midsole 24. The midsole 24 is preferably some distance above the bottom of the reactor, thus forming a lower additional chamber, i.e., the upper boundary of zone 26.

Fresh aromaattipitoista feed, which will be described below, is supplied to the system lead 46 along the extending line 40 of hydrogen stream, and the mixture continue to a line direction 40 of the arrow until this agrees with the line 44 is all the way down added to the condensed recycle liquid mixture was 34. The thus obtained from the separator is then passed through a conduit 42 into a hydrogenation upper end about At a temperature of 122 to about 302 ° C and a pressure of about 28.5 to about 107 aty, depending on the boiling range of the feedstock and the degree of hydrogenation. The lower temperature and pressure correspond to lower boiling feedstocks and a lower degree of hydrogenation.

The mixture of recycled feed liquid and hydrogen passes down through the catalyst bed in zone 16 under Adiabatic reaction conditions where a significant amount of the aromatics present in the total liquid charge are hydrogenated to the corresponding naphthenic compounds, 59810. The reaction mixture coming out of zone 16 is a biphasic mixture. The liquid phase is a mixture of paraffins, naphthenes and some unreacted aromatics. The effluent gas phase is a mixture of hydrogen, inert gaseous impurities and vaporized liquid hydrocarbons having a composition generally similar to that of the effluent liquid phase.

The liquid phase of the effluent flows downwards through the vapor separation zone 20 to the second hydrogenation zone 18 (through the intermediate base 14 which acts as a distribution plate).

In the reaction chamber 18, the hydrogen fed down line 48 and passing through the chamber 26 comes into contact with the liquid phase of the effluent in countercurrent, hydrogenating the remaining aromatics to the corresponding naphthenes. Hydrogen is fed without preheating, at a relatively low temperature compared to the liquid phase of the zone 16 effluent. The temperature of the hydrogen is generally not higher than about 38-49 ° C.

The liquid portion exiting the hydrogenation zone 18 remains briefly in the reactor chamber 26, allowing vapors to separate and closing the line 50 to prevent hydrogen escape. The liquid product is collected in line 50 and contains a very small amount, usually less than 1.5 volume *, of non-hydrogenated aromatics. The gas phase of the hydrogenation zone 18 effluent contains excess hydrogen, inert gaseous impurities, and vaporized hydrocarbons having a composition similar to that of the hydrocarbons contained in the hydrogenation zone 16 effluent gas phase.

The gas phases from the effluent streams of both the first hydrogenation zone 16 and the second hydrogenation zone 18 collect in the vapor separation zone 20. The combined gas phase fraction is discharged down line 28 and first passed through a heat exchanger, waste boiler 52. The steam mixture, which is still hot, is then passed down line 54, preferably first through a condenser 30 where it is used to preheat the mixture fed to the reactor, and then through a condenser 32 in which the remaining vaporized liquid phase components condense back into liquids. The resulting two-phase system, consisting of hydrogen gas, inert gases, and rehydrated hydrocarbons, is passed to a separator 34, where the liquid phase and the gas phase are separated. The liquid phase is passed along line 44 to be mixed with the feedstock to be fed to the hydrogenation zone 16 as described above. The gas phase, which consists of 5,598,810 hydrogen and inert gases, can be partially released into the atmosphere, e.g. up to line 56, to prevent the enrichment of inert contaminants in the system.

The remainder and most of this gas phase is recycled along line 36 for mixing with feedstock from line 1 of hydrogenation zone 16. Fresh feed gas can be passed from line 48 up line 58 to recycle gas if there is not enough recycle hydrogen for the first hydrogenation zone.

An important feature of this invention is internal temperature control. Reactions of the type in question are exothermic. Low outlet temperatures promote the production of jet fuel of the desired quality. In addition, uncontrolled reactions must be prevented or otherwise the formation of coke and unwanted by-products. Thus, processes for hydrogenating aromatics to jet fuel usually require external temperature control. Instead, the process of the invention provides inherent temperature control, especially in the second hydrogenation zone 18. As the hydrogen supplied from line 58 passes upward through this zone, some of the heat in this chamber is used to heat this hydrogen. Additional heat is consumed to evaporate the reaction product liquid in zone 18 to the extent that it is sufficient to saturate the gas stream exiting this zone to the steam separation zone 20. Similarly, the temperature of the first reaction zone 16 is controlled by the consumption of heat for partial evaporation of the feed liquid. The vaporized liquid is removed from the vapor separation zone 20 down line 28 as described above. A similar process for preparing cyclohexane from benzene using this same internal temperature control is described in Applicant's U.S. Patent No. 3,450,784.

The vaporized hydrocarbons recovered from the vapor separation zone 20 and used for recycling are part of a hydrogenated feed containing up to about 5% aromatics. Due to the low aroma content, the ratio of recycled material to fresh feedstock is less than 1: 1, generally about 0.05: 1 to 0.75: 1, and depends on a number of factors, e.g. the partial pressure and purity of hydrogen, the desired temperature in the reactor, etc.

The feedstock fed to the process is a petroleum fraction having a boiling range of about 57 to about 287 ° C. Fractions with a boiling range of, for example, 57-249 ° C, 177-266 ° C and 149-271 ° C are typical of those fractions in the above-mentioned wide boiling range which are suitable feedstocks for this process. The feed, 59810 b substance may be either straight-run or other petroleum fraction; fractions such as fuel oil, light and heavy naphthas, catalytic cracked cycle oils and heating oils may be used. Particularly suitable is a feedstock which generally boils in the boiling range of the fuel oil, i. between about 149 ° C and about 287 ° C.

When such a feedstock is used, the first hydrogenation zone 16 is operated at a temperature of about 149 to about 301 ° C and the second zone at a temperature of about 122 to about 255 ° C, in the aforementioned pressure ranges.

The process of the invention does not provide for the removal of sulfur compounds for practical purposes; as a result, most feedstocks must be desulfurized before being fed to the process, usually in a separate unit (not shown).

If sulfur compounds are removed from the feedstock just before it is fed to the first hydrogenation zone, it is generally so hot that it does not need to be further heated to bring it to the reaction temperature. If, on the other hand, the feedstock has been obtained from a simple fractional distillation process or has been allowed to cool before being fed into the process, or has been in storage, preheating is not necessary.

In any case, the hydrogen fed to the first hydrogenation zone 16 must be preheated before it is fed to this zone. Liquid recycled to this zone must also be preheated.

The preheating of hydrogen and, if necessary, the feedstock can be achieved in many ways and can be performed separately or together. A convenient method in this process is to utilize the heat content of the vapors flowing along lines 28 and 54 and exiting the vapor separation zone 20. The combined hydrogen (and feedstock as needed) is passed along line 42 along with the recycle liquid from line 44 through a heat exchanger 30 where it preheats to the desired inlet temperature by indirect heat exchange with partially cooled vapors flowing down line 54. This heat exchange may, in some circumstances, have the additional effect of partially condensing some of the hydrocarbons in the combined steam stream, facilitating the separation of the hydrocarbons for recycling from hydrogen and other gases in the separator 34.

If the fresh feed is already hot enough that it does not require preheating, it must be passed past the preheater to avoid overheating and unwanted side reactions. The fresh feed material is then fed into the system, for example down the line 43 instead of the line 46, or can be passed past the preheater in some other known way. In this case, only hydrogen and recyclable liquid hydrocarbons are preheated.

Alternatively, preheating of fresh feedstock, recyclable liquid and hydrogen can be performed in separate heat exchangers and the heated materials can be mixed together before being fed to the reactor. This separate preheating can be performed using any available heat source, including hot steam up to line 5.

The ratio of hydrogen to fresh feed in the mixture fed to zone 16 may range from a stoichiometric ratio of 1 mole of hydrogen per double bond, up to as high as about 300% of the stoichiometric requirement, and the ratio of hydrogen to liquid to reaction zone 18 may range from about , To 0 moles per mole.

L.H.S.V. the first zone 16 is preferably maintained between about 0.5 and about 6.0 based on fresh feed alone, but is generally at a higher level in the second zone 18. Total L.H.S.V. however, it is maintained between 0.5 and 6.0.

The temperature conditions in the second zone must be set so that the temperature of the effluent liquid product remains between about 1M9 and about 260 ° C, depending on the boiling range of the fresh feed, in order to obtain the best possible conditions for hydrogenation of aromatics to naphthenes and close to equilibrium.

It should be noted that it is not necessary to satisfy all the aromatics in the feedstock to produce jet fuel that meets the minimum smoke point requirement. Saturation of aromatics from 90 pounds is usually more than sufficient to meet this requirement; as noted above, up to 1.5% by volume of residual aromatics may remain in the product. However, even much lower aromatic concentrations can be achieved as shown in the example.

Most of the fuels made from the aforementioned feedstocks by the processes of this invention do meet the quality requirements for standard jet fuel, but their freezing point is not low enough to be used in faster airplanes (-49.5 ° 0 or less). In the case of some feedstocks, this quality requirement is also met. For example, it has been found that such jet fuel can be prepared from desulfurized fuel oil from Bachaquero crude oil by the method described herein.

To better illustrate the nature of the invention and its mode of application, the following specific example is set forth.

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Example

Desulfurized straight-run fuel oil having the following characteristics: ASTM distillation ASTM D-86-62

Boiling point at initial ° C 17 ^ 50 vol-? », ° C 199

End point, ° C 238

Aromatics by volume? », ASTM D-1319-65T 16.0

The smoking point, including ASTM D-1322-64 18.2, was mixed with hydrogen, then combined with the recycled liquid in a ratio of 16 parts recycled liquid per 100 parts of bulk feed, preheated in a heat exchanger 30 and fed to the top of the reactor 10. The inlet temperature at the upper end of zone 16 was 20 ° C; the maximum overall temperature of the catalyst bed was 27 ° C. The reaction was performed with an overall L.L.S.V. of 2.40 and a pressure of 64 aty. The hydrogenated product obtained up to line 50 contained aromatics in 0.55 vol. The smoke point improved to 36 mm, which is well above the minimum requirement of 25 mm.

Although the foregoing constitutes a description of the invention, it is in no way intended to limit the invention to the specific aspects mentioned in the description, as alternatives and equivalents will readily occur to those skilled in the art. The present invention is therefore not to be construed as limited by any claims other than the appended claims.

Claims (13)

5981 0 A process for preparing jet fuel fuels by hydrogenating in two stages a hydrocarbon feedstock having a boiling range of about 150 to 290 ° C and substantially free of sulfur-containing impurities, characterized in that (a) the feedstock is passed in co-flow with a first hydrogen-rich gas through a hydrogenation zone operating at a temperature of about 120-300 ° C and elevated pressure, in contact with the hydrogenation catalyst to at least partially hydrogenate the feedstock; (b) removing a gas phase effluent comprising hydrogen and vaporized liquids and a partially hydrogenated liquid phase hydrocarbon stream from the first hydrogenation zone; (c) hydrogenating said liquid phase hydrocarbon stream in a second hydrogenation zone operating at a temperature of about 90-260 ° C and elevated pressure, directing it to a second hydrogenation zone countercurrent to the hydrogen-rich gas stream, in contact with the hydrogenation catalyst, and (d) hydrogen and vaporized liquids, and a liquid phase effluent which is jet fuel. A method according to claim 1, characterized in that sulfur compounds are removed from the feedstock of the first hydrogenation zone before it is fed to said zone. A method according to claim 1, characterized in that the feedstock of the first hydrogenation zone is preheated before it is fed to this zone. A method according to claim 3, characterized in that the gas phase removal streams of the first and second hydrogenation zones are combined and conducted * to exchange heat indirectly with the feed material of the first hydrogenation zone so that the gas phase removal streams cool and said feedstock is preheated. A method according to claim 1, characterized in that the gas phase removal streams of the first and second hydrogenation zones are cooled to such an extent that their vaporized liquid components condense, and these liquid components are separated from the remaining gas components and returned to the first hydrogenation zone. A method according to claim 5, characterized in that most of said remaining gas components are returned to the first hydrogenation zone. 5981 0 ίο Process according to Claim 5, characterized in that the ratio of recycled liquid to fresh feedstock is 0.05: 1 to 0.75: 1. Process according to Claim 1, characterized in that the first hydrogenation zone operates in a temperature range of about 150 to 300 ° C. Process according to Claim 1, characterized in that the second hydrogenation zone operates in a temperature range of about 120 to 260 ° C. A process according to claim 1, characterized in that the second hydrogenation zone operates at a temperature such that the temperature of the liquid phase effluent leaving it is about 150-260 ° C. A method according to claim 1, characterized in that the boiling range of the hydrocarbon feedstock is in the temperature range of about 175 to 265 ° C. A method according to claim 1, characterized in that the boiling range of the hydrocarbon feedstock is in the temperature range of about 150-270 ° C. Process according to Claim 1, characterized in that the hydrocarbon feedstock is a straight-run fuel oil from which sulfur compounds have been removed. n 59810