DE2303755A1 - METHOD OF TREATMENT OF COOKER GAS - Google Patents

Description

Dr. W. P. Radt

Dipl.-Ing. E. E. Finkener Dr. G. Otto & Comp.

Dipl.-Ing. W. Ernesti society with "limited

Patent attorneys

463 Bochum liability

Heinrich-Koenig-Strasse 12

Telephone 4 IS 50.42327 4-650 BOC h U IH

Telegram address: Radtpatent Botftum

31/72
WPE / IK

Method of treating coke oven gas

The invention relates to a method for treating the coke oven gas, "in which it is initially indirectly cooled, is then treated with an aqueous solution in such a way that the ammonia content is below a predetermined value lies, and from the resulting aqueous solution the ammonia is driven off by means of water vapor.

In this way of working, which is generally referred to as the indirect method, in most cases of use of the coke oven gas, which was purified in this way, the requirement made that the ammonia content the value of 2 g / 100 Nm ^ gas does not exceed. That sets you Sufficiently low ammonia content of the washing solution in advance at least in the last stage of the ammonia washing; around To secure this, you must either constantly! fresh water in sufficient quantity to the last stage of the Ατηπιoniakwasiiers given or the aqueous solution remaining when the ammonia is driven off must be worked up in such a way that it is suitable for scrubbing the gas with ammonia.

The ammonia obtained when the aqueous solution is driven off can be converted into usable products in many ways further processed; if economic utilization is not possible, it can also be done after separation burn the steam and the addition of suitable fuels at high temperatures in such a way that this creates harmless substances that can be released into the atmosphere.

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Fresh water that is used for the last stage of the ammonia washer is only available in limited quantities in some areas. It is therefore in many ways there is a need that "when the ammonia is driven off from the aqueous solution is still in such water Way to treat it again to scrub the ammonia Coke oven gas can be used, for which of course a sufficiently low content of free ammonia in the aqueous Solution condition is.

In some of them the ammonia expeller can be used Drained aqueous solution cannot simply be poured into the receiving water because it has too high a content of toxins and in particular still contains too much ammonia. To harm the toxins contained in this water To make it, it can be used in a known manner to extinguish the hot coke during its manufacture the coke oven gas is obtained. The water is evaporated and the substances it contains are carried through the heat of the coke partially decomposes, partially they are attached to the coke, partially they form no longer harmful vapors} the presence of phenols in the extinguishing vapors can be counteracted by that the ammonia-containing water before the expulsion of the Ammonia is one of the well-known dephenolation processes is subjected or that the phenol is removed from the wastewater itself. Those that were deposited on the coke when it was extinguished Substances remove the silvery appearance of the coke, but they do not degrade its quality and become when the coke is burned or when it is used in the blast furnace, it is largely converted into harmless substances.

The elimination of the pollutants contained in the wastewater however, by using the waste water when extinguishing the hot coke has a limit as that when indirect method of gas treatment in the coking plant

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The amount of water that accumulates is greater than that which "is evaporated when the coke is extinguished. It falls regularly a certain amount of water from the natural moisture of the coal, also from the formation water. Added to this is the water used for the ammonia scrubbing " of which only a part "evaporates when the ammonia is driven off, and finally that during the various processes accumulating steam condensates. Even if, therefore, a certain amount of wastewater is generated by extinguishing the hot coke can be rendered harmless, there is still a need to render harmless in this way To keep the amount of water below a certain amount.

It is the aim of the present invention to reduce the amount of waste water containing harmful substances as much as possible to be kept low and, if necessary, that for ammonia leaching to save the necessary amount of fresh water in whole or in part by removing the ammonia expeller draining water at least partially such a treatment is subjected to that again for ammonia scrubbing is usable.

This is done according to the invention in such a way that the process of the abortionist, that is, the one after the abortion of the ammonia remaining aqueous solution is cooled and at a suitable temperature with an OOp-containing Bringing gas into contact in such a way that the partial pressure of the remaining free ammonia in the aqueous solution increases a value suitable for leaching the ammonia from the coke oven gas drops. Because it was already by G. Eymann (GWT Volume 90, page 506) found that the ammonia pressure of a solution that contains not only ammonia but also carbon dioxide is reduced to a fraction of that of carbonic acid free solution is decreased. In the case of a MoI

ratio 3 of 1.0, the ammonia partial pressure goes to CO.,

'2

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about 10% Has zurücko the drained from the stripper water, for example, an ammonia partial pressure, the g an ammonia content of the gas of for example 12 in 100 corresponds only, so it is possible, through appropriate aeration of the aqueous ammoniakalisehen solution at the thus treated gas, the ammonia content to a below of the prescribed value of 2 g ammonia in

Nnr gas to reduce the amount lying.

The most varied of types can be used as COp-containing gas Gas mixtures are used, if possible those that occur in sufficient quantities on the plant in question, to which the coking plant belongs. Requirement is, that they do not contain admixtures that are used for the ammonia scrubbing of the gas by inclusion aqueous solution bring unwanted components into the coke oven gas.

A suitable gas containing COp is, among other things the purified coke oven gas. As a rule, a partial flow of the same is sufficient, which after contact with the aqueous, from the draining solution is returned to the raw gas stream.

The COp-containing gas is advantageously pressurized brought into contact with the aqueous solution running off from the aborter} this creates the CO «pressure during the gassing process elevated.

The gassing may be carried out in the remaining ammonia at the temperature of laundry or a higher temperature, for example at 40 ⁰ C. This requires a stronger or weaker cooling of the abortion drain before the gassing. The temperature mentioned has an influence on the speed with which CO 2 forms ions in the aqueous solution, as a result of which the partial pressure of the ammonia

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is reduced.

Plants for treating the coke oven gas in accordance with the present invention are shown in the accompanying drawings shown, namely relates

Figure 1 shows a system in which the fumigated discharge of the ammonia expeller in addition to fresh water for Serves to wash the ammonia out of the gases, while,

Figure 2 relates to a system that can be operated without the addition of fresh water.

The same reference symbols denote the same parts in both figures:

The gas entering the receiver 12 from the coke ovens 10 via the riser pipes 11 passes through the pipeline 13, to which a tar separator 14 is connected, into the gas cooler 15 - the ones in the apparatuses 14 and 15 Formnoniakhaltigen condensates are over the Line 16 withdrawn and fed to a dephenolation plant 17.

After passing through the electrostatic precipitator 18, the gas is fed through the line 19 to the lower part of the ammonia washer 20. The gas drawn off at the dome of the ammonia washer through line 21 passes through the gas suction device 22, then the gas aftercooler 23 and is through the line 24 for further treatment or use

In Figure 1 it is provided through the line 25 to the ammonia washer to supply fresh water in the last stage, which is distributed via the nozzles 26 or distributor trays will. A lower stage of the ammonia washer will do this

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dephenolated water or a Part of the same fed through the line 27 and distributed by means of further nozzles.

The drainage of the ammonia washer 20 withdrawn through the line 28 is in the preheated state at 30 in the Aborter 29 introduced, steam enters at 31. Part of the washer drain is - not preheated - by the Line 32 placed on the top floor of the aborter 29 wovimr. The ammonia expeller 29 by the Line 33 leaving vapors consist mainly from ammonia and water vapor. They can be worked up in any way, e.g. the one contained here Ammonia, optionally with the addition of a fuel be burned at such high temperatures that the combustion gases are safely released into the atmosphere can.

The aqueous solution draining through line 34, the still has a considerable ammonia vapor pressure is partially drained through line 35. When the sanitary Regulations permit, this water can be given into the receiving water. You can do it through the line 35 draining water also for extinguishing of hot coke, with the contained therein volatile components are decomposed and go into the atmosphere with the extinguishing steam.

A portion of the flow passing through the conduit 34 aqueous solution is fed via line 36 and a cooler 37 to the aerator 3 ⁸ supplied and handled here in counter-current with a supplied through the conduit 39 part stream of the purified gas. The gas withdrawn at the tip of the fumigator through line 40 is fed to the coke oven gas before the ammonia scrubbing, either via line 41 into line 19 or line 42 into

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line I3. Shut-off and control organs 43 and 44 permit any division of the by, the line 40 withdrawing Fumes. The solution drawn off at the bottom of the fumigator 38 through the line 45 is so low Ammonia partial pressure that it is suitable for sufficient ammonia leaching. You can immediately do the Nozzles 26 or - depending on the amount of fresh water available - also in a previous stage in the ammonia washer 20 are abandoned.

Depending on the amount of fresh water available, one can give a greater or lesser proportion of return gas to the gasifier and the abortion process in abortion 29 and operate the gassing process in the gasifier 38 accordingly.

The system according to FIG. 2 operates under very similar conditions. Here too, gas cooling is the first step intended. Here, too, the gas water is fed to a dephenolation system 17. However, it then arrives not into the ammonia washer, but is fed via line 46 to a further stripper 47, the at 48 steam is supplied.

The expelled vapors reach a line 33 » which also absorbs the vapors from the further aborter 29 to which the ammonia washer 20 drains through the Line 28 is supplied. The procedures of the abortionists 29 and 47 are in the allowable amount of sewer 35 supplied. A part of the abortion process also arrives here via the line 36 and the cooler 37 into the fumigator 38.

The temperature at which the aqueous solution is supplied to the gasifier depends on the extent of the action of the cooler 37 flows in.

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The withdrawn through line 39 from line 24 Purified gas is brought to an increased pressure of e.g. 2 to 5 atmospheres by means of the compressor 49 and so fed to the gasifier.

The withdrawn through line 45 at the bottom of fumigator 38 aqueous solution has such a low ammonia partial pressure that it is used solely for feeding the ammonia washer 20 can serve. A cooler 50 is installed in the line 45, which opens the outlet of the fumigator brings the temperature of the ammonia wash.

The new method is very diverse in its application possibilities, in particular it can be adapted to the maximum amount of allowable wastewater, to the maximum values of toxins that the wastewater may contain, the amount of fresh water available for ammonia washing and the possibility of using the ammonia vapors obtained.

Claims

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Claims (4)

Claims 1. Process for the treatment of the coke oven gas, in which it initially cooled indirectly, then treated with an aqueous solution in such a way that the ΪΠϊ ^ content is below a predetermined value and the ammonia from the resulting aqueous solution by means of water vapor is aborted, characterized in that the remaining after the abortion aqueous solution and cooled with a GOp-containing gas is brought into contact in such a way that the partial pressure of the remaining free ammonia in the aqueous solution drops to a value suitable for leaching the ammonia from the coke oven gas. 2. A method for treating the coke oven gas according to claim 1, characterized in that the COp-containing Gas is part of the purified coke oven gas, which after contact with the aqueous, draining from the aborter Solution is returned to the raw gas stream. 3. The method according to claim 1 or 2, characterized in that that the GO ^ -containing gas under pressure with that of the abortionist running aqueous solution is brought into contact. 4. The method according to any one of the preceding claims, characterized in that the contact with the COp-containing Gas at a temperature above which the ammonia scrubbing of the gas takes place. 409831/0544 Blank page