DE2537640B2 - Process for driving off bound ammonia from the aqueous condensates and effluents from carbonization and coking - Google Patents

Description

The Krfindiing concerns a procedure / to Abireiben of ammonia from aqueous liquids, especially from the aqueous condensates of carbonization and coking of coal or brown coal. Bitumen slate or I orf, as well as the wastewater from the work-up of the smoldering and coking gases. in which that Ammonia of low volatility. Brand acids is bound, the aqueous .1 I liis gkciten with aqueous Solutions or suspensions of milfidium, alkaline Substances are mixed, ι e to absorb hydrogen sulfide from oases of the Verschweliing oiler Coking have served and then the mixture is heated.

Treatment of condensates from coke oven gas and the waste water from gas scrubbing with milk of lime b / w. Calcium hydroxide is known and described in detail at »(). Oroskinsky. Manual of the coking plant "Volume II, Düsseldorf 14'3H. Ropes Ή and the following.

Working with calcium hydroxide in the form of Lime milk is cumbersome and it is known that it also requires a special column, mainly because of the low solubility of calcium hydroxide in water. Since in -: len aqueous condensates of the Smelting and coking, usually with the effluents of the scrubbing of the raw coke oven gas are worked up together, carbonals are always present, is the formation of almost insoluble Calciunikarbonat hardly avoidable, which is easy cause / 11 There are blockages in pipes. The economic management of the company allows at this point but usually not the use of a more valuable hydroxide, e.g. an alkali hydroxide such as sodium hydroxide, which forms a water-soluble carbonate instead of calcium hydroxide.

It has been proposed in a process to drive off bound ammonia from ammonia water in an ammonia stripping column in which a strong base is added to the ammonia water, to use a sodium sulfide waste liquor as a strong base (DE-PS 24 12 026) and it is still good has been proposed in a method for the purification of coke oven gas, in which from the de-tarred and cooled raw gas the ammonia with water, if necessary with the addition of sulfuric acid, and scrubbing the hydrogen sulfide through a scrubbing circuit containing sodium or potassium carbonate from which the hydrogen sulfide is expelled with carbonic acid and that for the purpose To keep the washing solution clean, certain amounts of caustic soda or potassium hydroxide are constantly supplied and appropriate Quantities of washing liquid are withdrawn from the hydrogen sulfide scrubbing cycle

M) to mix the scrubbing liquid removed with the waste water of the ammonia scrubbing and then the released Drive off ammonia (DE-PS 25 05 459).

In the proposed method, large amounts of expensive alkalis are now always in use. the

i °> Amounts are great that for clearing the in that Condensate coal water and the ammonia washing water of the raw gas of coking only a small amount Part of it is needed. Even the ones to keep the Stoichiometrically often stoichiometric amounts of hydrogen sulfide scrubbing solution to be rejected from the circuit are adhered to even more alkaline substances than for releasing deep total fixed ammonia in the combined coal sub Washing water is needed.

It is the underlying task of the invention

2J now. the required amount of alkali increases significantly decrease and s ;: the one to free the ammonia to adjust the necessary quantities.

To achieve the object, according to the invention, in a method of the type defined at the outset, as

m> aqueous, alkaline, sulfidic solutions such as sodium-potassium oiler Liiliiiim-Ahfall-I.aiigen used the the hydrogen sulphide washing of ammonia have already served pre-cleaned coke oiler carbonization gases. The pre-cleaned gases only contain

> '■ a fraction of the original hydrogen sulfide content and consequently it is alkaline for the washing out of the rest is less and comes the alkali requirement for the! - "travel sec of the bound Ammonia from coal and ammonia wash water

i "closer.

It has proven to be particularly expedient to carry out a conventional pre-cleaning of the gas according to the principle of Nlli-H.'S-Krcislaiif scrubbing. Here about H (VAt ties are contained in the raw gas

■ f 'hydrogen sulfide washed out and it succeeds without special additional expenditure, / .. B. from gaseous ammonia, to produce a pre-cleaned gas that maintains about 1.0 g I I_> S per Nm ¹ . If the remaining 11> S content is now removed with an alkali lye wash,

ϊ ·> men should be so wiril because of the inevitable simultaneous absorption of carbon dioxide as well as other acids the alkali in the amount required and implemented, which is also responsible for the release of the total bound ammonia contained in the combined

^r >> th sewage, Kohlcwasscr and Ciaswaschwasser is contained. In the case of an economically managed operation, the waste liquor from the H ₂ S -Cias scrubbing does not contain any free hydroxide, as stated above, but only reaction products. the especially for

μ ('' travel of bound ammonia are suitable. An additional pollution of the Kokerci waste water with salts does not occur due to the sulfur purification of the gas.

The new method is followed by a

h ^r > Example explained with a schematic sketch.

In a coking plant, 100,000 Nm ^{1 of} raw coke oven gas with a HjS content of 8 g per Nm ¹ are produced every hour. The coke oven gas is of this IbS content and the

Coking plant wastewater must be freed from bound ammonia / u. For this purpose, the raw coke oven gas from line 1 is fed at a temperature of 25-30 "C to pre-desulphurization 2 of desulphurization 2u. igen aqueous Nlli solution up to a content of ^{10g per Nm 1.} Since '·: NHi water enriched with HjS from the circular wash runs from 2 through line 3a and is / is regeneration, ie to drive off the acidic components HjS , COj and HCN. pumped into the Entsaurer. 4 the pre-treated coke oven gas rises aui 2 in the fine cleaner 5 of the desulfurization 2.7 onto which dti ^r ch line 6 hour 12.5 m ¹ sodium hydroxide solution, the JVO kg NaOH r containing abandoned The finely cleaned coke oven gas exiting through line 7 contains less than 0.1 g H..S per Nm '. NaüH solution enriched with H, S. CO .. and HCN collects on the bottom of 5. It only contains insignificant ju amounts of NaOII and they will through L 'ilting t abandoned on öai lower part of NHi-Aborters 4. 45 m 'of hydrocarbon water, d. ι. Aqueous condensate from the Kiiksofengav abandoned, through line 11 about HtI iei / steam. From y, the sump of S, waste water is drawn off through line 12, which only contains traces of ammonia. Otherwise it only contains the sal / quantity. which alone corresponds to ammonia that has been bound to it.

All volatile parts of the coal water passed through the lines 13-14 to deacidification column 4 using steam. The Daiupfmengc introduced by 11 to 9 is calculated in such a way that the acidic proportions of the ammonia water enriched in 2 and reaching through 3; / to 4 are also driven off. Regenerated, ie deacidified ammonia water collects in the sump around 4 and is again introduced by Vuienischweicluiv 2 through line .1. This completes the cycle of the \ iii: in mi.ikvA water. Losses of water are compensated for by means of the connecting piece Ib. At the head by 4 are l.eitung 15 all from the Koksol: _{i) r} '.is and ilen washing liquids taken lluchtigeit and fleeting-made components such as read uisprunuluh free and the originally bound BEEN ammonia, the HJS. the carbonic acid and the IKN in I'onn deducted from Wasserdampfbrüdeii. This wenlcu ir. Aulgearheiiet known manner hamlet. where the hydrogen sulfide and the aniline. "i.ik can be isolated and obtained in n >>, ruΙι · ιη. · ι known form. The NHi can be burned or decomposed according to also known \ etlalKei ;.ιικίι.

The amount given hourly to 5 - .. JTDkL ¹ NaOIi corresponds to siochiometnsLh iei / e ^ i ^ 'iJcnen amount of ammonia which is in the dm> h I

the abortionist
is included.

iiL ¹ H) aül 9 abandoned -4 ">m'.Kohlcwjssjr

For this I Hi.itt drawings

Claims (1)

Palent claim: Process for stripping bound ammonia from aqueous liquids, in particular the aqueous condensates of the smoldering and coking of hard coal and lignite, bituminous shale and peat and the waste water from the processing of the smoldering or coking gases, in where the ammonia is bound to slightly volatile, strong acids, the aqueous liquids are mixed with aqueous solutions or suspensions of sulphidic alkaline substances, which is used to absorb hydrogen sulfide from gases of smoldering or coking and then the mixture is increased, characterized in that as aqueous alkaline solutions such sodium, potassium, lilhium waste alkalis are used, t'ie the Hj-S-Wäii'he of already pre-cleaned with ammonia Have served coke or smoldering oases.