METHOD FOR PRODUCTION OF AVIATION FUEL

Abstract

A process plant and a process for production of a hydrocarbon fraction suitable for use as jet fuel from an oxygenate feedstock, which may be a feedstock being a renewable feedstock, including combining the feedstock with a diluent hydrocarbon stream to form a hydrotreatment feed stream to contact a material catalytically active in hydrotreatment under hydrotreating conditions to provide a hydrotreated intermediate product, directing at least an amount of said hydrotreated intermediate product to contact a material catalytically active in hydrocracking under hydrocracking conditions to provide a hydrocracked intermediate product, separating the hydrocracked intermediate product in a hydrocracked intermediate liquid fraction and a gaseous fraction, directing at least an amount of said hydrocracked intermediate liquid fraction to contact a material catalytically active in hydrodearomatization under hydrodearomatization conditions to provide a treated product comprising the hydrocarbon fraction suitable for use as jet fuel.

Claims

1. A process for production of a hydrocarbon fraction suitable for use as jet fuel from an oxygenate feedstock, comprising the steps of a. combining the feedstock with a diluent hydrocarbon stream to form a hydrotreatment feed stream to contact a material catalytically active in hydrotreatment under hydrotreating conditions to provide a hydrotreated intermediate product, b. directing at least an amount of said hydrotreated intermediate product to contact a material catalytically active in hydrocracking under hydrocracking conditions to provide a hydrocracked intermediate product, c. separating the hydrocracked intermediate product in a hydrocracked intermediate liquid fraction and a gaseous fraction, d. directing at least an amount of said hydrocracked intermediate liquid fraction to contact a material catalytically active in hydrodearomatization under hydrodearomatization conditions to provide a treated product comprising the hydrocarbon fraction suitable for use as jet fuel.

2. The process according to claim 1, wherein an amount of said hydrocracked intermediate liquid fraction is directed as said diluent hydrocarbon stream.

3. The process according to claim 1 wherein step c comprises separating the hydrocracked intermediate product according to boiling point, providing a hydrocracked intermediate jet product having T10 above 205° C. and final boiling point below 310° C. according to ASTM D86.

4. The process according to claim 1, wherein step b or d further comprises directing a stream for isomerization being either said hydrotreated intermediate product, said hydrocracked intermediate product or said treated product to contact a material catalytically active in isomerization under isomerization conditions, to provide an isomerized stream being used in step b or d as said hydrotreated intermediate product, said hydrocracked intermediate product or said treated product respectively.

5. The process according to claim 1 wherein an amount of the hydrocracked intermediate product optionally after separation according to boiling point, and at least comprising a hydrocarbon fraction boiling above 310° C., is directed to be combined with either said feedstock or said hydrotreated intermediate product.

6. The process according to claim 1 wherein step b comprises separating the hydrotreated intermediate product in a liquid hydrotreated intermediate product and a gaseous fraction, and optionally the further step of separating the liquid hydrotreated intermediate product according to boiling point, providing a hydrotreated intermediate jet product having T10 above 120° C. and final boiling point below 310° C. according to ASTM D86.

7. The process according to claim 1 wherein the process conditions are selected such that the conversion, defined as the difference in the amount of material boiling above 310° C. in said hydrocracked intermediate product and the amount of material boiling above 310° C. in said hydrotreated intermediate product, relative to the amount of material boiling above 310° C. in said hydrotreated intermediate product, is above 20%.

8. The process according to claim 1 wherein said treated product comprises less than 1 wt/wt % aromatics, calculated by total mass of aromatic molecules relative to all hydrocarbons in the stream.

9. The process according to claim 1 wherein a hydrogen rich stream comprising at least 90 vol/vol % hydrogen is directed to contact the material catalytically active in hydrodearomatization, and wherein an amount of said gaseous fraction is optionally purified and directed to contact the material catalytically active in hydrotreatment.

10. The process according to claim 1 wherein the treated product is directed to a gas/liquid separator to provide a second stage gaseous fraction and a treated intermediate jet product which is directed to a further means of separation to provide said hydrocarbon fraction suitable for use as jet fuel and a treated product off gas.

11. The process according to claim 1, wherein hydrotreatment conditions involve a temperature in the interval 250-400° C., a pressure in the interval 30-150 Bar, and a liquid hourly space velocity in the interval 0.1-2 and wherein the material catalytically active in hydrotreatment comprises one or more sulfided metals taken from the group of nickel, cobalt, molybdenum or tungsten, supported on a carrier comprising one or more refractory oxides.

12. The process according to claim 1, wherein hydrocracking conditions involve a temperature in the interval 250-400° C., a pressure in the interval 30-150 Bar, and a liquid hourly space velocity in the interval 0.5-4, optionally together with intermediate cooling by quenching with cold hydrogen, feed or product and wherein the material catalytically active in hydrocracking comprises (a) one or more active metals taken from the group platinum, palladium, nickel, cobalt, tungsten and molybdenum, (b) an acidic support taken from the group of a molecular sieve showing high cracking activity, and (c) a refractory support.

13. The process according to claim 4, wherein isomerization conditions involves a temperature in the interval 250-350° C., a pressure in the interval 30-150 Bar, and a liquid hourly space velocity in the interval 0.5-8 and wherein the material catalytically active in isomerization comprises an active metal taken from the group comprising platinum, palladium, nickel, cobalt, tungsten and molybdenum, an acidic support, and an amorphous refractory support comprising one or more oxides taken from the group comprising alumina, silica and titania.

14. The process according to claim 1, wherein hydrodearomatization conditions involve a temperature in the interval 200-350° C., a pressure in the interval 20-100 Bar, and a liquid hourly space velocity (LHSV) in the interval 0.5-8 and wherein said material catalytically active in hydrodearomatization comprises an active metal taken from the group comprising platinum, palladium, nickel, cobalt, tungsten and molybdenum, and a refractory support.

15. A process plant for production of a hydrocarbon suitable for use as a jet fuel from a feedstock being a renewable feedstock or an oxygenate feedstock, comprising a hydrotreatment section, a hydrocracking section and a hydrodearomatization section, said process plant being configured for e. directing the feedstock to the hydrotreatment section to provide a hydrotreated intermediate product, f. directing at least an amount of the hydrotreated intermediate product to the hydrocracking section to provide a hydrocracked intermediate product, directing at least an amount of said hydrocracked intermediate product to a hydrodearomatization section to provide a treated product comprising the hydrocarbon fraction suitable for use as a jet fuel.

Description

FIGURES

[0063] FIG. 1 shows a process according to the present disclosure.

[0064] FIG. 2 shows a simplified illustration of a process according to the present disclosure.

[0065] FIG. 3 shows a simplified illustration of a process according to the prior art.

[0066] FIG. 1 shows a process layout for production of a hydrocarbon suitable for use as jet fuel (106) from a renewable feedstock (2) added stepwise (2a, 2b and 2c) to a hydrotreatment section (8). A first amount of the renewable feedstock (2c) is combined with a diluent (6) and directed to a hydrotreatment section (8) where it contacts a material catalytically active in hydrotreatment (10a). Further amounts of renewable feedstock (2b, 2c) and an amount of hydrogen rich gas (12a) are directed to contact individual beds of catalytically active material (10b, 10c, 10d) under hydrotreating conditions. This provides a hydrotreated intermediate product (14). The hydrotreated intermediate product (14) is directed to a hydrocracking section (16) to contact a material catalytically active in hydrocracking comprising a base metal (18a, 18b) under hydrocracking conditions, as well as a material catalytically active in isomerization comprising a base metal (20) providing a hydrocracked intermediate product (22). In a gas/liquid separator (24) the hydrocracked intermediate product (22) is separated into a gaseous fraction (26) and a liquid fraction (34). The gaseous fraction (26) is split in an optional purge (28) and a recycle gas (30) which is pressurized (32) and directed as quench hydrogen supply of the hydrotreatment section (12a) in one or more positions between reactor beds as well as to the hydrocracking section (12b, 12c). The liquid hydrocracked intermediate product (34) is directed to a stripper (36), which also receives a stripping medium (38) and optionally a stripper overhead recycle (40). From the stripper a gaseous stripper product (42) is directed to a gas/liquid separator (44), from which an off-gas (46) and a light naphtha fraction (48) are withdrawn. An amount of the light naphtha is withdrawn as product (50), an amount (52) may optionally be directed as feed (102) to a kerosene stabilizer (100) and an amount is directed as overhead recycle (40) to the stripper (36). The liquid stripper product (54) is directed to fractionator (56), from which a light overhead stream (58) is directed to an overhead vessel (60), from which a heavy naphtha (62) is withdrawn. An amount of heavy naphtha (64) is withdrawn as product and a further amount (66) is directed as fractionator recycle (66). A bottom fraction (68) is split in to a recycle stream (72) and a reboiled stream (74). From a side column (78) a hydrocracked intermediate jet product (80) is combined with a of hydrogen rich stream (84c) and directed as feed (82) to a hydrodearomatization and hydrodewaxing section (86), where it contacts a material catalytically active in isomerization (88) and a material catalytically active in hydrodearomatization (90a, 90b) under hydrodearomatization conditions, receiving further hydrogen rich streams (84a, 84b), providing a treated product (92), which is directed to a product gas/liquid separator (94) from which a second gaseous fraction (96) is withdrawn and combined with the recycle stream (72) and provided as make-up hydrogen in the diluent (76) to the hydrotreatment section (8). An intermediate jet product (98) is withdrawn from the product separator, and directed to a further means of separation (100), such as a kerosene stabilizer, optionally also receiving an amount of light naphtha (102), from which a liquid product (104) is withdrawn and split in a hydrocarbon fraction suitable for use as jet fuel (106) and a reboiler liquid (110). The gaseous overhead from the kerosene stabilizer (108) is combined with the gaseous stripper product (42) and directed to a gas/liquid separator (44).

[0067] In a further embodiment (not shown) the second gaseous fraction (96) is not directed as make-up gas for the hydrotreatment section, but instead directed to the a hydrodearomatization and hydrodewaxing section (86), possibly requiring an additional compressor, but also resulting in added simplicity. In this case make-up hydrogen is then added separately to the hydrotreatment section.

[0068] In a further embodiment the gaseous overhead from the kerosene stabilizer (92) may be handled in a separate overhead circuit with the benefit of simplicity and independence, but at the cost of extra equipment items for cooling, separation and reflux pumps.

[0069] In a further embodiment the separator, fractionation and light ends recovery sections can be configured in multiple ways as it is known to the skilled person. If light materials like LPG or propane are valuable, the recovery of these can be improved by using a sponge oil absorption system e.g. using the heavy naphtha from the fractionator overhead as lean oil and returning the rich oil to the stripper.

[0070] FIG. 2 is a simplified figure showing a layout similar to that of FIG. 1, omitting supply of gaseous streams and details of separation for simplicity. A renewable feedstock (202) is combined with a diluent (226) and directed as a hydrotreatment feed stream (204) together with an amount of a hydrogen rich stream (not shown) to a hydrotreatment section (HDO) where it contacts a material catalytically active in hydrogenation under hydrotreating conditions. This provides a hydrotreated intermediate product (206). The hydrotreated intermediate product (206) is directed to a hydrocracking section (HDC) operating under hydrocracking conditions, providing a hydrocracked intermediate product (212), which is directed to a fractionation section (FRAC) shown for simplicity as a single unit, separating the hydrocracked intermediate product in a light overhead stream (220), a naphtha stream (222), a hydrotreated intermediate jet product (224) and a bottom fraction (226). The bottom fraction (226) is directed as a recycle stream, which, as mentioned, is combined with the renewable feedstock (202). The hydrotreated intermediate jet product (224) is directed as feed to a post treat section (PT), where it contacts a material catalytically active in isomerization (ISOM) and a material catalytically active in hydrodearomatization (HDA) under hydrodearomatization conditions, providing a treated jet fuel product (218).

[0071] FIG. 3 shows an example of the prior art, in a level of detail similar to FIG. 2, omitting supply of gaseous streams and details of separation for simplicity. A renewable feedstock (302) is combined with a recycle diluent stream (310) and directed as a hydrotreatment feed stream (304) together with an amount of a hydrogen rich stream (not shown) to a hydrotreatment section (HDO) where it contacts a material catalytically active in hydrogenation under hydrotreating conditions. This provides a hydrotreated intermediate product (306), from which gases are separated e.g. in a stripper (SEP), providing a sweet hydrotreated intermediate product (308), which is split into said recycle diluent stream (310) and an isomerization feed (312) which is directed to a hydroisomerization section (ISOM) where it contacts a material catalytically active in isomerization under isomerization conditions, providing a dewaxed intermediate product (314).

[0072] The dewaxed intermediate product (314) is directed to a hydrocracking section (HDC) where it contacts a material catalytically active in hydrocracking under hydrocracking conditions, providing a hydrocracked product (316). The hydrocracked product (316) is directed to a fractionation section (FRAC) shown for simplicity as a single unit, separating the hydrocracked product in a light overhead stream (320), a naphtha stream (322), a jet product (324) and a bottom diesel fraction (326).

EXAMPLES

[0073] The performance of the process layouts shown in FIGS. 2 and 3 have been compared, based on two similar feedstocks, and process conditions optimized for maximum jet yield.

[0074] Table 1 shows the characteristics of a renewable feedstock which is a mixture of 50% used cooking oil and 50% animal fat. The feedstock comprises 6% aromatics and 80% boils above 500° C.; mainly due to the presence of high boiling triglycerides.

[0075] Feedstock A was treated in a process in accordance with FIGS. 2 and 3, and the results of this treatment is shown in Table 2.

[0076] In the hydrotreatment a significant conversion of boiling point is seen due to triglycerides being converted to alkanes. In addition, an amount of conversion is observed in the hydrocracking reactor and the isomerization reactor. The true conversion per pass is however quite low, since the amount of recycle is high.

[0077] The results of both examples show a production of a jet fuel with excellent properties, a low freezing point (−40° C.) and a low aromatics content (<0.5 wt/wt %). The example according to the present disclosure (FIG. 2) has a jet yield of 63 wt/wt %, whereas the Example according to the prior art (FIG. 3) has a jet yield of 58 wt/wt %. In addition, naphtha is produced in both scenarios. In a process designed for production of jet, the yield difference of 5% is of course valuable.

[0078] The configuration of FIG. 2, where the product of hydrodeoxygenation and hydrocracking is split in a light and a heavy fraction and the heavy fraction is recycled, results in a full conversion of heavy feedstock to jet product, and thus a higher yield of jet product compared to the configuration of FIG. 3.

TABLE-US-00001 TABLE 1 SG 0.9209 Aromatics in feed, wt/wt % 6 destillation: SimDist, wt/wt % IBP 340  5% 365 10% 398 20% 533 30% 582 40% 597 50% 601 60% 602 70% 608 80% 610 90% 611 95% 612 FBP 695

TABLE-US-00002 TABLE 2 Example FIG. 2 FIG. 3 P 70 barg 70 barg T(HDO) 320° C. 320° C. T(HDC) 380° C. 310 T(DWX) 325° C. 320 LHSV (DWX) 1 2 LHSV HDC 0.8 1 Freezing pt Jet −40° C. −40° C. Aromatics content in jet boiling range <0.5 wt/wt % <0.5 wt/wt % Naphtha boiling range yield 15 11 (bp. 30-110° C.), wt/wt % Jet boiling range yield 63 58 (bp. 110-310° C.), wt/wt % Heavier than jet yield — 11 (bp. 310-370° C.), wt/wt %