Process for Hydrotreating a Diesel Fuel Feedstock with a Feedstock of Natural Occurring Oil(s), Hydrotreating Unit for the Implementation of the Said Process, and Corresponding Hydrorefining Unit

Abstract

The invention relates a process for the catalytic hydrotreating of a feedstock of petroleum origin of diesel fuel type introduced into a stationary bed hydrotreating unit upstream of a feedstock of natural occurring oil(s) characterized in that the feedstock of natural occurring oil(s) contains acyl-containing compounds having 10 to 24 carbons including fatty acid esters and free fatty acids and said feedstock of natural occurring oil(s) is submitted to a refining by a hydrodynamic cavitation before its introduction into the stationary bed processing.

Claims

1.-15. (canceled)

16. A process for catalytic hydrotreating comprising: introducing a feedstock of petroleum origin of diesel fuel type into a stationary bed hydrotreating unit upstream of a feedstock of natural occurring oil(s), wherein the feedstock of natural occurring oil(s) contains acyl-containing compounds having 10 to 24 carbons including fatty acid esters and free fatty acids; refining the feedstock of natural occurring oil(s) before its introduction into the stationary bed, wherein the refining comprises a hydrodynamic cavitation processing in the presence of water under conditions efficient to generate cavitation features and to transfer at least a part of impurities contained in the natural occurring oil(s) into an aqueous phase, and separating the aqueous phase from an oil phase and recovering the oil phase as a refined oil; and pre-treating the refined oil to further remove impurities and to obtain a pre-treated oil.

17. The process according to claim 16, characterised in that the pre-treatment performed is chosen among a bleaching process in which the refined oil is contacted with an absorbent, a process in which the refined oil is contacted with an ion-exchange resin, a mild acid wash of the refined oil, a process using guard-beds, filtration, solvent extraction.

18. The process according to claim 16 wherein the natural occurring oil(s) contain(s) one or several oils chosen among vegetable oil, animal fat, waste food oils, by-products of the refining of vegetable oil(s) or of animal oil(s) containing free fatty acids, tall oils, and oil from produced by bacteria, yeast, algae, prokaryotes or eukaryiotes.

19. The process according to claim 16, characterised in that at least one degumming agent is added to the natural occurring oil(s) in the hydrodynamic cavitation processing.

20. The process according to claim 20, characterized in that the degumming agent is chosen from among water, steam, acids and complexing agents.

21. The process according to claim 16, characterized in that the feedstock of petroleum origin is injected into a first catalytic region of the hydrotreating unit and in that the feedstock of natural occurring oil(s) refined is injected into a second catalytic region of the hydrotreating unit situated downstream of the first catalytic region.

22. The process according to claim 16, characterized in that the hydrotreating unit is formed of a single reactor into which the feedstocks of petroleum and the feedstock of natural occurring oil(s) refined are injected.

23. The process according to claim 16, characterized in that the hydrotreating unit is formed of two separate reactors and in that the feedstock of petroleum origin is injected into the first reactor and the the feedstock of natural occurring oil(s) refined is injected into the second reactor as a mixture with the liquid effluent exiting from the first reactor.

24. The process according to claim 16, characterized in that the space velocity (LHSV) of the feedstock of petroleum origin is less than the space velocity of the the feedstock of natural occurring oil(s) refined, as a mixture with the effluent resulting from the treatment of the feedstock of petroleum origin.

25. The process according to claim 16, in which the feedstock of petroleum origin of diesel fuel type is chosen from the diesel fuel fractions originating from the distillation of a crude oil and/or of a synthetic crude resulting from the treatment of oil shales or of heavy and extra heavy crude oils or of the effluent from the Fischer-Tropsch process, the diesel fuel fractions resulting from various conversion processes, in particular those resulting from catalytic and/or thermal cracking (FCC, coking, visbreaking, and the like).

26. The process according to claim 16, in which the level of the feedstock of natural occurring oil(s) refined is up to 15% by weight with respect to the feedstock of petroleum origin and the feedstock of natural occurring oil(s).

27. The process according to claim 16, in which a light fraction comprising C4-C15 hydrocarbons, is added to the natural occurring oil(s) in the hydrodynamic cavitation processing step.

28. The process according to claim 16, characterised in that a gas stream comprising dihydrogen, carbondioxide, dihydrogensulfide, methane, ethane, propane or mixtures thereof, is added to the natural occurring oil(s) in the hydrodynamic cavitation processing step.

29. The process according to claim 16, in which the light fraction is a naphtha fraction, optionally recovered from the fractionation of the effluent of the hydrotreating process.

Description

[0248] The invention is now described with reference to the appended nonlimiting drawings, in which:

[0249] FIG. 1 is a simplified diagram of a unit 1 for the conventional hydrorefining of a feedstock of diesel fuel type;

[0250] FIG. 2 is a simplified diagram of a separation section of a conventional hydrorefining unit;

[0251] FIG. 3 is a simplified diagram of a hydrotreating unit according to a first embodiment of the invention comprising a single reactor;

[0252] FIG. 4 is a simplified diagram of a hydrorefining unit comprising a hydrotreating unit according to a second embodiment of the invention comprising two reactors.

[0253] FIG. 5 represents table 1

[0254] FIG. 1 represents a simplified diagram of a unit 1 for the conventional hydrorefining of a feedstock of diesel fuel type. This unit 1 comprises a reactor 2 into which the feedstock to be treated is introduced by means of a line 3. This reactor comprises one or more hydrorefining catalyst beds.

[0255] A line 4 recovers the effluent at the outlet of the reactor 2 and conveys it to a separation section 5.

[0256] A heat exchanger 6 is placed downstream of the reactor on the line 4 in order to heat the feedstock moving in the line 3 upstream of the reactor.

[0257] Upstream of this heat exchanger 6, a line 7, connected to the line 3, supplies an H.sub.2-rich gas to the feedstock to be treated.

[0258] Downstream of the heat exchanger 6 and upstream of the reactor 2, the feedstock mixed with the H.sub.2-rich gas moving in the line 3 is heated by a furnace 8.

[0259] Thus, the feedstock is mixed with the hydrogen-rich gas and then brought to the reaction temperature by the heat exchanger 6 and the furnace 8 before it enters the reactor 2. It subsequently passes into the reactor 2, in the vapour state if it is a light fraction and as a liquid/vapour mixture if it is a heavy fraction.

[0260] At the outlet of the reactor, the mixture obtained is cooled and then separated in the separation section b, which makes it possible to obtain: [0261] an H.sub.2S-rich sour gas G, a portion of which is reinjected into the H.sub.2-rich gas mixed with the feedstock by means of a line 9, [0262] light products L which result from the decomposition of the impurities. This is because the removal of sulphur, nitrogen, and the like, results in the destruction of numerous molecules and in the production of lighter fractions, [0263] a hydrorefined product H with a volatility similar to that of the feedstock but with improved characteristics.

[0264] Conventionally, the effluent exiting from the reactor 2 is cooled and partially condensed and then enters the separation section 5.

[0265] Such a separation section 5 generally comprises (FIG. 2): [0266] a first high-pressure knockout vessel 10 which makes it possible to separate a hydrogen-rich gas G(H.sub.2) from the effluent, it being possible for this gas to be recycled, [0267] a second low-pressure (10 bar) knockout vessel 11 which separates the liquid and vapour phases obtained by reducing in pressure the liquid originating from the high-pressure knockout vessel 10. The gas G(H.sub.2, L, H.sub.2S) obtained comprises mainly hydrogen, light hydrocarbons and a large part of the hydrogen sulphide formed in the reactor, [0268] a stripper 12, the role of which is to remove the residual and light hydrocarbons L from the treated feedstock. The hydrorefined product H is withdrawn at the base of this stripper,

[0269] a dryer 13, which makes it possible to remove the water dissolved by the hot hydrorefined product in the stripper.

[0270] According to a first embodiment, a catalytic hydrotreating unit according to the invention is formed of a single reactor 20, as represented in FIG. 3. This reactor 20 is provided with a first inlet 21 for the introduction of a feedstock of petroleum origin (ep) of diesel fuel type and a second inlet 22 for the introduction of a feedstock of biological origin (Cb) refined by hydrodynamic cavitation, the second inlet 22 being situated downstream of the first inlet 21.

[0271] Preferably, the inlet 21 for the feedstock of petroleum origin is conventionally situated at the top of the reactor.

[0272] The reactor 20 comprises several catalytic beds which are divided into two catalytic regions: a first region situated upstream of the second inlet 22, intended for the treatment of the feedstock of petroleum origin, and a second region B situated downstream of this second inlet 22, intended for the treatment of the feedstock of biological origin refined by hydrodynamic cavitation.

[0273] The first catalytic region A will preferably comprise a catalyst which promotes the hydrodesulphurization of the feedstock of petroleum origin.

[0274] The second catalytic region B will preferably comprise a catalyst which promotes the deoxygenation of the feedstock of biological origin refined by hydrodynamic cavitation. Advantageously, this region B comprises at least one first bed comprising an NiMo-based catalyst and a final bed comprising a catalyst with an isomerizing role which makes it possible to improve the low-temperature properties of the product.

[0275] Furthermore, the reactor 20 comprises an inlet 23 for the introduction of hydrogen 142 in the first catalytic region A and preferably a second inlet 24 for introduction of hydrogen H.sub.2 in the second catalytic region B, these injections of 112 acting as gaseous quench.

[0276] Finally, it is possible to allow an inlet 25 for the introduction of water in the catalytic region B, this injection B making it possible to promote the conversion to CO.sub.2 of the CO which may have been formed.

[0277] The reactor forming the catalytic hydrotreating unit 20 according to the invention can be used in a conventional hydrorefining unit such as that described with reference to FIG. 1, as replacement for the reactor 2 of this unit.

[0278] According to a second embodiment, a catalytic hydrotreating unit according to the invention is formed of two reactors 30, 31. FIG. 4 represents a hydrorefining unit equipped with such a catalytic hydrotreating unit.

[0279] The diagram of this hydrorefining unit is very similar to that of the unit represented in FIG. 1.

[0280] The first reactor 30 of the catalytic hydrotreating unit according to the invention is preferably identical to the reactor 2 of FIG. 1. The feedstock of petroleum origin Cp is conveyed to the top of this reactor by means of a line 32 but the liquid effluent exiting from this first reactor, instead of being directed to a separation section, is sent to the top of the second reactor 31 by means of a line 33.

[0281] A line 34 conveying the feedstock of biological origin refined by hydrodynamic cavitation Cb joins the line 33 before it enters the top of the second reactor 31.

[0282] A line 35 recovers the liquid effluent at the outlet of the second reactor 31 and conveys it to a separation section.

[0283] Just as for a conventional unit, a heat exchanger 36 is placed downstream of the first reactor 30 on the line 33 in order to heat the feedstock Cp moving in the line 32 upstream of the first reactor 30.

[0284] Preferably, the hydrorefining unit according to the invention additionally comprises a second heat exchanger 37 placed downstream of the second reactor 31 on the line 35 which also heats the feedstock Cp moving upstream of the first reactor 30, this second exchanger 37 being, for example, placed upstream of the first exchanger 36.

[0285] Upstream of these heat exchangers 36 and 37, a line 38 connected to the line 32 supplies an H.sub.2-rich gas to the feedstock Cp to be treated.

[0286] Downstream of the heat exchangers 36, 37 and upstream of the first reactor 30, the feedstock of petroleum origin mixed with the H.sub.2-rich gas moving in the line 32 is heated by a furnace 39.

[0287] The liquid effluent is cooled at the outlet of the second reactor 31 and then separated in a separation section which comprises a first, high-pressure hot knockout vessel 40 which makes it possible to separate, horn the effluent, a hydrogen-rich gas G(H.sub.2) also comprising CO and CO.sub.2. This gas G(H.sub.2) is conveyed to another low-pressure cold knockout vessel 41, then conveyed to a unit 42 for the treatment and separation of CO.sub.2, for example an amine absorber, and then to a unit 43 for the separation and treatment of CO of the PSA type. The CO separated in this unit 43, as well as the other gases separated, such as CH.sub.4, C.sub.2H.sub.6, C.sub.3H.sub.8, and the like, can advantageously be sent to an SMR unit for the production of hydrogen H.sub.2. This hydrogen can then optionally be returned in the line 44 bringing back the recycle gas to the first reactor 30 as gaseous quench and in the line 38 for the treatment of the feedstock Cp.

[0288] The liquid effluent exiting from the first knockout vessel 40 is, for its part, directed to another low-pressure (10 bar) knockout vessel 45 which separates the liquid and vapour phases obtained by reducing in pressure the liquid originating from the high-pressure knockout vessel 40, The gas G(H.sub.2, L, H.sub.2S) obtained comprises mainly hydrogen, light hydrocarbons and a large part of the hydrogen sulphide formed in the reactor. The liquid effluent resulting from this knockout vessel 45 is conveyed to a steam stripper 46, the role of which is to remove the residual H.sub.2S and light hydrocarbons from the treated feedstock. The gaseous effluent exiting from the knockout vessel 45 can be sent to another knockout vessel 47 fed with the liquid effluent exiting from the knockout vessel 41, the liquid effluent of which is also conveyed to the stripper 46. The gas exiting from this knockout vessel 47 can be made use of.

[0289] The hydrorefined product H is withdrawn at the base of this stripper 46.

[0290] The separation unit described above and composed of the knockout vessels 40, 41, 45 and 47, of the stripper 46 and of the treatment units 42, 43 can, of course, be used at the outlet of the single reactor described in FIG. 3. Depending on the conditions, it is also possible to allow only two successive knockout vessels 40 and 41, the liquid effluents of which are directed directly to the stripper 46.

[0291] A portion of the hydrorefined product H can be introduced into the second reactor via a line 48 in order to act as liquid quench. Heat exchangers 49, 50, respectively placed on the lines 34 and 32, can be used for the preheating of the feedstock of biological origin refined by hydrodynamic cavitation and of the feedstock of petroleum origin respectively.

[0292] The hydrorefined product H may be further fractionated into LPG, naphtha, Jet fuel and diesel fractions. The naphtha fraction may be partly recycled to be refined by hydrodynamic cavitation with the feedstock of biological origin. Alternatively, a naphtha fraction from another unit may be refined by hydrodynamic cavitation with the feedstock of biological origin.

[0293] Just as in the preceding embodiment with one reactor, it is possible to allow for injection of water 51 into the second reactor 31.

[0294] This unit thus makes it possible to carry out the hydrorefining of petroleum fractions in the first reactor 30 and to finish the hydrorefining of the petroleum fractions in the second reactor 31, and also to deoxygenate the triglycerides of the feedstock of biological origin refined by hydrodynamic cavitation.

[0295] In addition, it is clearly apparent that the second reactor can be easily isolated from the circuit by means of valves, a bypass line directly conveying the liquid effluent exiting from the first reactor to the separation and treatment devices. Thus, this hydrorefining unit can be used for the hydrotreating of a feedstock of petroleum origin, with or without addition of a feedstock of biological origin refined by hydrodynamic cavitation.

[0296] The following examples illustrate the advantages produced by the process according to the invention.

EXAMPLES

[0297] Examples 1-4 have been performed using a laboratory hydrodynamic cavitation device fabricated by installing a Venturi tube in a hydrodynamic cavitation setup equipped with a pump at the inlet and a pressure controller at the outlet. The Venturi tube has an orifice opening (throat diameter) of 0.75 mm and an orifice length (throat length) of 1 mm, a wall of 25 inclination (related to the flow axe) at the inlet (convergent section) and a wall of 6 inclination (related to the flow axe) at the outlet (divergent section). The pipes to the Venturi convergent and divergent sections have a diameter of 5 mm and a length of 50 mm.

[0298] The phosphorus content of raw rapeseed and hydrodynamic cavitation processed product has been measured by means of ICP (Inductive Coupled Plasma).

Ex. 1

[0299] Raw rapeseed oil (10 kg) was mixed with 2 wt % water, well mixed and pressure increased with, the aid of the pump in order to have a ratio outlet pressure to inlet pressure of less than 0.75. At an outlet pressure of 2 bars the mixture rapeseed, oil and water was passed through the hydrodynamic cavitation device at 40 C. While the raw rapeseed oil had a phosphorus content of 811 wppm the rapeseed product after cavitation treatment and separation of the aqueous phase by centrifugation, has a phosphorus content of 26 wppm.

Ex. 2

[0300] The raw rapeseed oil (10 kg) was mixed with 2 wt % of a water solution containing 10 wt % of citric acid 0.2 wt % citric acid on oil basis) and stirred vigorously for 30 minutes. The pressure was increased with the aid of the pump in order to have a ratio outlet pressure to inlet pressure of less than 0.75. At an outlet pressure of 2 bars the mixture rapeseed oil and water was passed through the hydrodynamic cavitation device at 40 C. While the raw rapeseed oil had a phosphorus content of 811 wppm the rapeseed product after cavitation treatment and separation of the aqueous phase by centrifugation, has a phosphorus content of 1 wppm.

Comparative Ex. 3

[0301] Raw rapeseed oil (10 kg) was mixed, with 2 wt % water, well mixed and heated to 65 C. during 30 minutes in a lab vessel at a stirring speed of 500 rpm. The aqueous phase was separated by centrifugation. The phosphorus content has dropped from 811 wppm to 120 wppm.

Comparative Ex. 4

[0302] Raw rapeseed oil (10 kg) was mixed with 2 wt % of a water solution containing 10 wt % of citric acid (0.2 wt % citric acid on oil basis), well mixed and heated to 65 C. during 30 minutes in a lab vessel at a stirring speed of 500 rpm. The aqueous phase was separated by centrifugation. The phosphorus content has dropped from 811 wppm to 51 wppm.

Ex. 5

[0303] In a small pilot unit, a nickel-molybdenum on alumina catalyst was loaded and presulphurised with DMDS/SRGO mixture under dihydrogen. The product of example 2, having only 1 wppm of remaining phosphorus was processed in order to deoxygenate the triglycerides at about 275 C. and 80 barg (hydrogen to liquid ratio of 900 N1/1). The LHSV was 1 h1. Nearly full deoxygenation could be reached during more than 1000 hours on stream without any deactivation nor plugging of the pilot unit.

Comparison Ex. 6

[0304] In the same small pilot unit, the product of example 4, having still 51 wppm of remaining phosphorus was processed in order to deoxygenate the triglycerides at about 275 C. and 80 barg (hydrogen to liquid ratio of 900 N1/1). The LHSV was 1 h1. Nearly full deoxygenation could be reached during only 20 hours on stream after which plugging of the pilot unit started with increase of inlet pressure. Semi-quantitative analysis (about 10% error) by means of XRF (X-ray fluorescence spectroscopy) showed that the material constituting the plug was significantly enriched in phosphorus (more than 2000 wppm) compared to only 51 wppm in the feedstock.