EP0116180A1 - Process for smoldering hydrogenation residues - Google Patents

Abstract

The residues resulting from the hydrogenation of oil, in particular heavy oil or coal, are smoldered in a drum, in particular a rotating drum, at temperatures from 400 ° C. to 600 ° C., with carbonization gas after separating off the condensable components and heating to 600 ° C. to 950 ° C is led into the smoldering drum. The gas is particularly indirectly by means of the combustion of oil or gas, e.g. B. heated by excess carbonization gases from the flue gases to the temperatures of 600 ° C to 950 ° C. The residue to be smoldered is introduced into the hot gas in a particularly fine distribution, preferably by atomization.

Description

In the hydrogenation of coal and mineral oils, in particular distillation residues of mineral oils and heavy and heavy oils at temperatures from 400 ° C to 520 ° C and pressures from 100 bar to 700 bar in the bottom phase, the hydrogenation product contains the desired reaction temperature volatile components non-volatile residues such as asphaltenes, catalysts and unreacted coal in the hydrogenation of coal or coal or coke as a catalyst carrier in the hydrogenation of oil. The residues are separated from the gaseous product in one or more hot separators and have to be worked up. In the coal hydrogenation process used in Germany until the end of World War II, the residues, possibly after increasing the solids content by centrifuging, were placed in a smoldering plant in which the non-volatile constituents were decomposed into gas, oil and coke.

A common smoldering plant for the hydrogenation residues consisted of a slightly inclined rotating drum, heated from the outside with gas burners, into which the pasty residue, preheated to around 400 ° C to 450 ° C, was introduced and smelted at temperatures of around 550 ° C to 600 ° C . (compare W. Krönig "The catalytic pressure hydrogenation of coal, tars and mineral oils", Berling / Göttingeri Heidelberg 1950, especially pages 44/45 and 188/189 as well as M. Höring and EE Donath in "Ullmanns Encyclopedia of Technical Chemistry" 3rd edition , Volume 10, Munich / Berlin 1958, especially pages 518/519.) To prevent coke build-up on the drum, it contained steel balls that knocked off the build-up when it was circulated. About 100 kg of water vapor per ton of feed product were passed into the drum as the purge gas.

In this known method, the specific throughput of the smoldering drum was essentially determined by the heat to be introduced into the drum per m ^{2 of} drum surface. By preheating the residue to be smoldered as far as possible to the cracking temperature, the heated area of the drum could be reduced accordingly or the throughput of the drum increased. However, since the preheating temperature was limited by the start of cracking reactions during heating, this type of throughput increase was limited.

Because of the indirect heating of the smoldering drums over their walls, this process was very energy-intensive and not very economical, the noise caused by the steel balls falling inside the drum was considerable and the cleaning of the smoldering water produced during the condensation from the water vapor introduced as a purge gas was very expensive. Therefore, experts believed that such smoldering furnaces or smoldering processes would no longer be possible in the future (see Winnacker-Küchler, "Chemical Technology", Munich / Vienna 1981, Volume 5, page 457).

Surprisingly, it has now been found that these disadvantages of the drum swelling of hydrogenation residues can be avoided if the drum contents, the carbonized material, are heated directly by means of a heating gas heated to temperatures of 600 ° C. to 950 ° C. Smelting gas, in particular, serves as the heating gas after its condensable components have been removed. The heating gas is therefore at a higher temperature than the steam used previously; it acts not only like that as a purge gas, but also in particular as a heating medium for the smoldering of the hydrogenation residues.

The carbonizing gas serving as the heat transfer medium is circulated between smoldering drum, condensation and reheating. The condensation takes place in a customary manner, with the absence of water vapor compared to the earlier process simpler conditions which lead to less environmental pollution. The condensation stage can also be made smaller and the coolant consumption reduced. The heat generated during the combustion of the carbonization gas not required as a cycle gas, which is indirectly transferred to the cycle gas via a heat exchanger, can be used for the reheating of the cycle gas.

The method according to the invention enables a specific throughput increase of 50% for a given drum size and a lower specific heating gas requirement compared to the known method with carbonization preheating. For a certain throughput, the drum can be downsized with direct heating by circulating gas.

Since the smoldering does not take place on the drum wall, as in the earlier method, but rather inside the drum, the tendency to form coke deposits on the drum walls is lower. The caking can be further countered by the fact that the char is in a fine distribution, for. B. atomized, is introduced into the heating gas. It is therefore not necessary to use steel balls in the drum. However, it may be appropriate to use solids, e.g. B. fine coke particles, which arose in the earlier course of smoldering, as germs for further coke deposits with the char.

As already mentioned, the heat necessary for the smoldering of the hydrogenation residues is essentially introduced into the smoldering drum by the smoldering gas circulated brings. The heating of the drum shell is therefore unnecessary; however, it has proven to be expedient to return the heat lost through radiation to it. This can be done by additional heating, the z. B. is operated with excess flue gas.

The method according to the invention is explained below with reference to the accompanying drawing.

The hydrogenation residue 6 is z. B. with a temperature of 370 ° C in the rotary drum 1, where the smoldering takes place. The drum is inclined, mounted on rollers and driven by a motor. The heat required for smoldering is directly by recycled smoldering gas 7 with z. B. a temperature of 600 ° C - 950 ° C. In the embodiment of the method shown, carbonized material 6 and heating gas 7 are conducted in cocurrent. Both can also be performed in countercurrent. The coke 12 formed during the smoldering is discharged from the drum via a suitable device.

The carbonization gases 11 are led to the condensation 2, in which the carbonization oil 13 is separated. The uncondensed portions of the carbonization gas are drawn off with the blower 3, a partial flow 14 being conveyed back to the rotary drum 1 for further processing and a partial flow 7 via the heat exchanger 4. The flue gases 15 produced in the combustion chamber 5 by burning heating gas 10, in particular carbonization gases 14 not required as recycle gas, with air 9 are cooled in the heat exchanger 4 against the recirculated carbonization gas 7, the heat required for direct heating of the drum being obtained.

Indirect heating of the drum by means of the flue gases 15 generated by combustion of heating gas 10, in particular carbonization gas 14, with air 9 in the combustion chamber 5 serves to compensate for the heat loss and to start the process.

Solids 8, in particular lime and / or coke, can be added to the rotary drum to incorporate pollutants during the smoldering process and to favor the coke separation.

Claims (3)

1. A process for smoldering in the hydrogenation of oil, especially heavy oil, or coal accumulating residues in a heated drum, in particular a rotating drum, at temperatures of 400 ° C to 600 ° C with the supply of a hot gas in the smoldering drum, characterized that as the hot gas carbonization gas is used after separating the condensable components and heating to 600 ° C to 950 ° C. 2. The method according to claim 1, characterized in that the heating of the low-temperature gas carried as recycle gas to 600 ° C to 950 ° C indirectly by means of the combustion of oil or gas, e.g. B. occurs from excess carbonization smoke gases. 3. The method according to claim 1 or 2, characterized in that the residues are introduced in a fine distribution in the hot gas, in particular atomized.

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