Claims
- 1. In a method of hydrotreatment in at least two stages, of a heavy hydrocarbon fraction containing asphaltenes, sulfur impurities and metallic impurities, wherein:
- (a) in at least one first hydrodemetallization stage, the hydrocarbon charge and hydrogen are passed over a hydrodemetallization catalyst in a hydrodemetallization zone or zones, and
- (b) in at least one subsequent hydrodesulfurization stage, the product of stage (a) and hydrogen are passed over a hydrodesulfurization catalyst,
- the improvement wherein the hydrodemetallization zone or zones is or are preceded by two protective zones in parallel, each containing a fixed bed of a hydrodemetallization catalyst, the two protective zones operating only alternately, one off-stream and one on-stream, and wherein the volume of each protective zone has sufficient demetallization capacity to provide sufficient time to permit the off-stream protective zone to be treated and placed on-stream, so as to permit the exchanging of the protective zones without stopping the unit or decreasing the capacity of the unit.
- 2. The method of claim 1, wherein each of said protective zones has substantially the same volume as a hydrodemetallization zone.
- 3. The method of claim 1, wherein the volume of feed per volume of catalyst per hour in the working protective zone is from 0.5 to 1.5.
- 4. The method of claim 3, wherein the volume of feed per volume of catalyst per hour is from 0.8 to 1.2.
- 5. The method of claim 1, wherein the catalyst used in the protective zones contains a carrier and from 0.1 to 30% by weight, counted in metallic oxides, of at least one metal or metal compound from at least one of groups V, VI or VIII of the Periodic Table, in the form of a plurality of juxtaposed conglomerates each formed by a plurality of acicular tips, the tips of each conglomerate being directed generally radially of one another and radially of the center of the conglomerate.
- 6. The method of claim 1, wherein a processing section is associated with the protective zones and enables them to be exchanged while in operation, without stopping the unit, said section being regulated so as to process the catalyst contained in the off-stream protective zone at a pressure of 10 to 50 bars.
- 7. The method of claim 6, wherein said pressure is from 15 to 25 bars.
- 8. The method of claim 1, for treating a charge comprising a heavy oil or a heavy oil fraction containing asphaltenes, wherein the charge is first subjected to hydroviscoreduction conditions, mixed with hydrogen, before being passed into the protective zones.
- 9. The method of claim 1, wherein the charge has a metal content of 100-400 ppm.
- 10. The method of claim 9, wherein the charge has a metal content of more than 250 ppm.
- 11. The method of claim 6, wherein the charge has a metal content of 100-400 ppm.
- 12. The method of claim 11, wherein the charge has a metal content of more than 250 ppm.
- 13. A method according to claim 1, comprising an upstream hydrodemetallization and at least one downstream hydrodemetallization zone operating continuously in series, wherein each hydrodemetallization zone is conducted in a separate reactor, the upstream zone being preceded by said two protective zones conducted in separate reactors.
- 14. The method of claim 13, wherein the charge has a metal content of 100-400 ppm.
- 15. The method of claim 13, wherein the charge has a metal content of more than 250 ppm.
- 16. A process according to claim 1, wherein the hydrodemetallization stage operates at a continuous 100% capacity until the hydrodesulfurization stage is shut down.
Priority Claims (1)
Number |
Date |
Country |
Kind |
90 04153 |
Mar 1990 |
FRX |
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Parent Case Info
This is a continuation of U.S. Ser. No. 07/677,179, filed Mar. 29, 1991, now abandoned.
US Referenced Citations (9)
Foreign Referenced Citations (2)
Number |
Date |
Country |
0113297 |
Jul 1984 |
EPX |
2124252 |
Jul 1983 |
GBX |
Continuations (1)
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Number |
Date |
Country |
Parent |
677179 |
Mar 1991 |
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