US2065963A - Process for the operation of retorts and chamber ovens - Google Patents

Description

29, 1936. F. BREITBACH PROCESS FOR THE OPERATION OF RETORTS AND CHAMBER OVENS Fil ed Jan. 5, 1954 rammed- Dec. 29, 1936- 4 PROCESS FOR THE OPERATION OF 'BE- TORTS AND CHAMBER OVENS Fritz Breitbach, Recklinghausen, Germany, assignor to Carl Still Gesellschatt mit bcsch'rinkter Haftnng, Recklinghausen, Germany Application January 3, 1934, Serial No. 705,161 In Germany January 12, 1933 2 Claims.

In the known processes of drawing off the dis-- tillation products of externally heated retorts and chamber ovens in which the distillation products produced inside and outside the mass of fuel are drawn oiI separately by means of detachable outlet tubes which project into the interior of the mass of fuel, or in a known form of construction thus forming in a gas-tight connection with hollow ducts formed in the fuel mass, all the inner gases produced can only be completcly removed to the collecting main for the inner gas in the case of coals forming tar seams which are difficult to pass gas through, when high negative pressures or vacua, which in pn ac tice are not very desirable, are used. The process of coking such coal by the use of the known internal suction devices is carried out insuch a manner that in each particular case only the proportion of the entire quantity of gas which can be collected with a definite maximum vacuum is carried off to the collecting main for the inner gases and the rest is carried ofi through the usual ascending pipe from the gas collecting space into the collecting main for the outer gas which is under a slight vacuum.

The removal of the inner and outer gases together to the collecting main for the inner gas which is under high vacuum has not hitherto been proposed as advantageous because it was assumed that the outer gases-as in the case of the usual high-temperature coking processwere in each stage of the coking, inferior to the inner gases particularly in respectof the lightoil content and the composition of the light oils and for this reason the quality of the inner gas or of the light oils and tars would be impaired if the two were mixed.

Experiments carried out with coke oven batteries provided with the'known internal suction devices have, strange to say, shown that by the use of internal suction the composition of the outer gases during the first part of the coking is afiected in such a manner that the quality of the light oil vapour and tar vapour contained therein is very similar to that in the inner gases and vapours. The duration of this first period of operation, when employing internal suction, during which the light oils and tars of the outer gases agree with the light oils and tars of the inner gases in respect of their specific gravity, amounts, for instance (with a carbonizing period of 34 hours and a coal with 23 per cent. volatile constituents at 11 per cent. water content) to about 4 hours. It-probably depends essentially upon the time required by the oven, after charging with fresh coking-coal, to completely reheat the walls and .particularly the arch of the chamher, as the heat in the masonry is at first considerably withdrawn by charging with the coal. It is also well known that the water content of the coking coal or of the outer gases which pass oil through the gas collecting space (or chamber) in consequence of the low concentration of the light oils or the tar vapours in the mixture of gas and steam, plays an important part in the protection of the gases and oils from pyrogenic decomposition.

Apparatus suitable for carrying out the process disclosed herein is illustrated in the accompanying drawing wherein the figure shown is a vertical longitudinal section through the center of a coke oven chamber, showing only a portion of the length and height of the chamber, and with the novel means for carrying off the gases of distillation.

Now the process according to the present invention consists in that during the first hours of coking all gases are carried off to the collecting.

main 1 for the inner gas, the outer gases being also sucked from the gas collecting space 4 without the interposition of suction tubes 3 to the collecting main 1 for the inner gas which is under partial vacuum. With this object in view, one or more of the gas suction tubes 3 which are distributed over the length of the chamber and which bridge the gas collecting space 4, are not inserted in the fuel mass I, so that the gas removal ways 5 and 6 in the roof of the oven provide a direct connection between the gas collecting space 4 and the collecting main 1 for the inner gas, in which there arebuiltregulating and closing devices [2 which in accordance with the pressure prevailing in the gas collecting space regulate the automatic removal of the outer gases from the gas collecting space or chamber to the collecting main 1 for the inner gas which is.

According to a further feature of the process according to the invention, after the conclusion of the above described first operative stage of coking, the removal of the outer and inner gases oocurs separately, 1. e. the suction tubes I conduct the gas from the interior of the fuel mass I through the known gas collecting pipes I and I to the collecting main 1 for the inner gas, and the previously performed direct removal from the gas collecting space to the collecting main for the inner gas ceases, but in its place the connection I to the collecting main 9 for the outer gas is established by the ascending pipe valve being opened. In this second coking stage-as experiments have shownthe light oils (benzine, benzene) and tars begin to be distributed to the outer and inner gas very differently as regards their amount and specific gravity, so that the carrying out of the withdrawal of the gases from the interior of the fuel and the gas collecting space separately is advantageous.

This second operative stage of the coking period hereinbefore referred to by way of an example embraces approximately the 4th22nd hour of carbonizing. At the end of the 22nd hour of carbonizing of generally after about twothirds of the carbonizing period, the tar seams in the middle of the oven chamber begin to close together-this may even occur with certain kinds of coal and at high coking speed after half the carbonizing time has elapsed. At this moment the gas suction tubes for the internal products are removed from the fuel mass or their gas-tight connection with the hollow channels in the fuel mass is broken and the collecting main for the inner gas disconnected from the respective oven.

Ithas been found that during the coking of the tar seam when using internal suction by premature condensation of tar vapours, the tar in the tar seam becomes enriched and the quality of the gases after the moment of withdrawal of the suction tubes rises temporarily until the tar seam or the tar which has accumulated in the hollow spaces of the fuel mass is evaporated or coked. In order that these valuable gases and vapours themselves may be again collected, according to a further step in the invention, at the end of the second operative stage of the coking period already referred to, the separate removal of inner and outer gas is interrupted and all sucbeing transferred in its full strength to the gas collecting space of the oven chamber.

Example.-In coking a coal having 23 per cent. volatile constituents and 11 per cent. water content within 34 hours, the sucked interior gases during the first three hours contained a light oil of specific gravity 0.74 at 20 and a tar of 0.88 at 20 of which 3l per cent. was distilled over at 180 C. From the 4th to the 12th hour of carbonizing the inner gases were carried on separately from the outer gases, the specific gravity of the light oil in the inner'gas remaining almost unchanged at 0.75 at 20, while that of the light oil in the outer gas rose to 0.87 at 20. The corresponding specific gravity in the case of the inner tar amounted to 0.92 and the outer tar to more than 1.1. Continuing separate removal up to the 22nd hour of carbonizing the specific gravities for benzene and tar in the outer gas remained the same, but those for the inner gas rose to 0.81 for benzlne-benzene and 0.99 or slightly over 1.0 for inner tar.

Of the operative stages described, the third may, of course, be omitted and instead after the withdrawal of the suction tubes from the inte rior of the fuel, all the gases be drawn oil as outer gases by the collecting main under partial vacuum.

What I claim is:

1. In the destructive distillation of a body of coal over a period of hours in a retort, the process comprising separately withdrawing to a common gas collecting main the gases of destructive distillation evolved from the interior of a body of coal and from the exterior thereof during the first hours of distillation, and thereafter independently withdrawing the interior and exterior gases evolved from said body of coal at a later stage to separate gas collecting mains.

2. In the destructive distillation of albody of coal over a period of hours in a retort, the process of independently withdrawing during the later stages of distillation the gases of destructive distillation evolved from the interior of said body of coal and from the exterior thereof to separate gas collecting mains, and this after previous withdrawal of gases evolved from the interior and exterior of the body of coal during the first hours of distillation to the collecting main for the gases evolved from the interior of the body of coal.

FRITZ BREITBACH.

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