EP0142043A2 - Process for the recuperation of vaporizable oils from hydrogenation residues of heavy oils, bitumen, tars etc. - Google Patents

Abstract

The residues from the hydrogenation of heavy oils or very heavy oils, bitumen, tar, oils from oil shale or tar sand and the like, are subjected to a vacuum distillation at pressures from 0.01 to 0.6 bar. For an improved process engineering procedure in the vacuum distillation of such hydrogenation residues, these are subjected to a distillation under reduced pressure in a single- or multi-shaft screw machine. <IMAGE>

Description

For the hydrogenation of heavy and heavy oils, bitumen, tar, oils from oil shale or tar sand and the like. Methods are known in which these feedstocks at temperatures of 250-550 ° C., preferably 350-490 ° C. and pressures of 50-700 bar , preferably 100-350 bar, optionally in the presence of catalysts. The hydrogenation of these high-boiling feedstocks at normal pressure produces, in addition to gaseous hydrocarbons and viscous or solid hydrogenation residues at room temperature, in particular lower-boiling liquid products in the gasoline and medium-oil boiling range as products (see W. Krönig, "The Catalytic Hydrogenation of Coals, Tar and Mineral Oils" , Springer Verlag, Berlin, Göttingen, Heidelberg 1950, in particular pp. 77 - 91).

The corresponding technologies were developed and used for technical maturity in the years 1920 to 1965. The basic process was the hydrogenation technology according to BERGIUS-PIER. Building on this process, special technologies have recently been developed and applied on a pilot or large-scale scale. H-OIL technology, LC-FINING, are newer developments as well as the VEBA COMBI CRACKING process (VCC) (see below RM Eccles, "Recent Technical Advances in H-OIL Upgrading of Heavy Crudes", Proc., Vol. II, 2nd World Congress of Chemical Engineering, 1981, p. 520 - 537); U. Graeser, K. Niemann, "Proven hydrogenation processes for upgrading residua being revived in Germany", Oil and Gas J., March 22, 1982, pp. 121, 122, 125-127).

All of these processes have in common that the separation of the hydrogenation residues from the gaseous or condensable products takes place in hot separators, the phase separation being carried out under reaction pressure at reaction temperature or at temperatures below it. The processing of the hydrogenation residues presents difficulties. In addition to solids such. B. catalysts and non-evaporable liquid or pasty components such. B. Asphaltenes valuable vaporizable product oils, the separation of which is imperative for economic reasons.

Various processes such as filtration, spinning, vacuum distillation, etc. were used to separate these evaporable oil admixtures. The oils obtained in the boiling range of the vacuum gas oil are e.g. B. converted into marketable, lower-boiling products by further hydrogenation. However, the amounts of oil separated by filtration or spinning contain e.g. T. considerable admixtures of difficult to hydrogenate oil-soluble high molecular weight laren substances such. B. asphaltenes, which adversely affect further hydrogenation or whose degradation requires more stringent hydrogenation conditions.

The aforementioned difficulties are overcome by using vacuum distillation. The oils obtained by vacuum distillation can be hydrated to higher quality products under relatively mild conditions. The process engineering of vacuum distillation of such hydrogenation residues is known, but the handling of the vacuum residue poses considerable problems. In particular, the discharge from the vacuum column and the transport for further processing are extremely difficult due to the high viscosity of the vacuum residue.

The object of the present invention is to overcome these difficulties. According to the invention, this is done by subjecting the residue to the hydrogenation of heavy or heavy oils, bitumen, tar, shale oils and the like in a single- or multi-shaft screw machine distillation under reduced pressure. The hydrogenation residue, which constantly increases its viscosity during the distillation, is continuously circulated by the screw and is thereby passed through the distillation zone of the screw machine, so that the evaporable constituents are removed from it.

Single- or multi-shaft screw machines with gas or steam discharge are known, for. B. from US Pat. Nos. 1,156,096 and 2,615,199. However, despite the difficulties already encountered in processing the hydrogenation residues of coal in the 1930s and 1940s, they have not been used to extract oil from hydrogenation residues, but e.g. . B. used to remove gases or monomer vapors from plastics (see M. Herrmann "screw machines in process engineering", Berlin / Heidelberg / New York 1972). In the plastics industry, the screw machine thus forms part of the polymerization reactor, the polymerization reaction being terminated by removing the monomers in the vacuum zone, whereas in the case of the hydrogenation of the aforementioned starting materials, the solidification in the hydrogenation residue is expedient.

When distilling the hydrogenation residue in the single- or multi-shaft screw machine, pressures of 0.01-0.6 bar, preferably 0.02-0.1 bar, are used in particular. According to a further development of the invention, the pressure drops from 0.6, preferably 0.1 bar to 0.01, preferably 0.02 bar over the length of the screw machine from the entry of the hydrogenation sludge to its exit. This measure reduces the risk of disturbances in the distillation process in the screw machine.

The distillation of the hydrogenation residue in the screw machine is carried out in particular at temperatures of 200-400 ° C., preferably 250-350 ° C. According to a further embodiment of the invention, the temperature increases from 200 ° C., preferably 250 ° C. to 400 ° C., preferably 350 ° C., over the length of the screw machine from the inlet to the outlet of the hydrogenation residue. This shortens the time during which the hydrogenation residue assumes high temperatures which favor changes and facilitates the further processing of the residue freed from the volatile constituents. Residues up to a final viscosity of approximately 2000 mPas (250 ° C.) can be handled in the distillate removal by the process according to the invention.

The gases withdrawn in gaseous form from the screw machine are expediently mixed with the other hydrogenating oils, e.g. B. combines the hot separator leaving gaseous hydrogenation products and together with these further treatment, for. B. subjected to a hydrogenation. According to a further embodiment of the invention, the non-evaporated material can be introduced from the screw machine into a cooling or granulating device, where it is solidified. The goods that can be stored and transported in this form can e.g. B. can be used as fuel or as a feed of a gasification plant.

According to another embodiment of the invention, the unevaporated material is heated in the screw machine after distillation to higher temperatures, preferably 350-600 ° C., and is smelted at this temperature, in particular at atmospheric pressure or at a pressure below it. For this purpose, the screw machine expediently has a smoldering zone in addition to the distillation zone, into which the hydrogenation residue is conveyed through the screws after passing through the former. The sulfuric vapors generated are extracted separately from the oil vapors. The resulting coke can finally z. B. can be used as fuel.

It is particularly favorable to further compress the material not evaporated in the screw machine after the distillation and to introduce it directly into a gasification reactor in which, for. B. is obtained via synthesis gas of the hydrogen necessary for the hydrogenation of the feed products of the hydrogenation process. For this purpose, in addition to the distillation zone, the screw machine expediently has a compression zone connected to a direct entry system into a gasification reactor.

The present method is suitable for processing all hydrogenation residues which occur in high-pressure hydrogenation processes of heavy or heavy oils, bitumen, tar, oils from oil shale or tar sand and the like, in which the starting material contains Hy Hydrogen hydrogen and optionally in the presence of a catalyst at elevated pressure and elevated temperature, for example by the so-called Bergius-Pier process.

The invention is further explained on the basis of the exemplary embodiment below and the drawing.

The residue from the vacuum distillation of a Venezuelan crude oil with an initial boiling point of above 325 ° C was in a hydrogenation plant, which works essentially on the basis of an advanced Bergius-Pier process, at 300 bar and 450 ° C with the addition of an inorganic catalyst system and with the addition of Hydrogen is hydrogenated and fed via line 1 to a hot separator 2, in which the gaseous reaction products are separated from the liquid and solid components of the reaction mixture at reaction pressure and reaction temperature. The gaseous constituents are drawn off via line 3 and processed further in the usual way. The non-volatile solid and liquid constituents leave the hot separator via line 4 and are fed to the vacuum screw machine 7 after expansion to atmospheric pressure via nozzle 6. In this case, the entry into the vacuum screw machine takes place from below into the liquid space, in order to thereby conclude the feed flow of the products from the hot separator to the vacuum zone of the vacuum screw machine 7. A positive-displacement pump system 5, which also serves as a metering unit, is used as the conveying element for the feed stream.

The product used in the vacuum screw machine consists of 0.86 t of oil with a boiling range of 200 - 550 ° C at normal pressure, 0.12 t of residue with a start of boiling of at least 550 ° C at normal pressure and 0.02 t of inorganic constituents.

The vacuum screw machine 7 was equipped with a double screw and, in the case of the present example, was divided into an evaporation zone 8 and a smoldering zone 9 over the length of the screw cylinder.

Over the length of the evaporation zone 8, the hydrogenation residue used is heated to 350 ° C. at 0.1 bar. 0.75 t of volatile constituents are drawn off via the connection piece 10 and passed into the condensate container 12 via line 11 following cooling which is not shown in the flow diagram. The condensate container is connected to the vacuum line 13 and the condensate is drawn off via line 15.

A constant increase in the viscosity of the residue used was observed in the evaporation zone 8. The feared deposits of solids on the screw and on the screw cylinder could not be observed.

The residue obtained from the evaporation zone 8 contained 0.13 t of oil constituents with a boiling range of about 450-500 ° C. under normal pressure, 0.10 t of a residue boiling above 550 ° C. under normal pressure and 0.02 t of inorganic constituents. This residue was heated in the smoldering zone 9 adjoining the evaporation zone 8 from 350 ° C. over the length of the smoldering zone to gradually increase to 600 ° C., the evaporation zone 8 and smoldering zone 9 being separated by a mechanical compression stage 16, thereby compressing the residue he follows.

In the smoldering zone 9, a further 0.21 t of distillate are obtained, which is drawn off via the connection piece 14 and via line 17. The resulting residue essentially contained only 0.02 t of coke-like products and 0.02 t of inorganic constituents and was compressed in a discharge zone 18 and drawn off via nozzle 19 and line 20.

The vacuum screw machine was heated by means of jacket heating by means of superheated steam in the evaporation zone 8 and by means of flue gas in the smoldering zone 9.

In a technically equivalent manner, the heating can also be carried out by means of electrically heated heating jaws or by induction heating or, in the case of jacket heating, by heat transfer oils.

Claims (11)

1. A process for the production of evaporable oils from the residue of the hydrogenation of heavy or heavy oils, bitumen, tar, oils from oil shale or tar sand and the like. By a vacuum distillation, characterized in that the hydrogenation residue in a single or multi-shaft screw machine a distillation is subjected to reduced pressure. 2. The method according to claim 1, characterized in that the distillation is carried out at pressures of 0.01 to 0.6 bar, preferably 0.02 - 0.1 bar. 3. The method according to claim 2, characterized in that the pressure drops from 0.6, preferably 0.1 bar to 0.01, preferably 0.02 bar over the length of the screw machine from the inlet to the outlet of the hydrogenation residue. 4. The method according to any one of claims 1 to 3, characterized in that the distillation is carried out at temperatures from 200 to 400 ° C, preferably 250 to 350 ° C. 5. The method according to claim 4, characterized in that the temperature of 200 ° C, preferably 250 ° C, increases to 400 ° C, preferably 350 ° C over the length of the screw machine from the inlet to the outlet of the hydrogenation residue. 6. The method according to any one of claims 1 to 5, characterized in that the non-evaporated material is introduced after distillation from the screw machine into a cooling or granulating device. 7. The method according to any one of claims 1 to 5, characterized in that the non-evaporated material in the screw machine after the distillation is preferably smoldered at temperatures of 350 to 600 ° C. 8. The method according to claim 7, characterized in that the smoldering takes place at atmospheric pressure. 9. The method according to any one of claims 1 to 5, characterized in that the non-evaporated material is compressed in the screw machine after the distillation and is introduced directly into a gasification reactor. 10. The method according to any one of claims 1 to 9, characterized in that the entry of the liquid hydrogenation residue into the screw machine (7) via a positive pump system (5) from below into the liquid space. 11. The method according to any one of claims 1 to 10, characterized in that the screw machine (7) has an evaporation zone (8) and a smoldering zone (9) which are separated from one another by a mechanical compression stage (16).

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