DE1669326C - Process for cleaning coking plant raw gases - Google Patents

Description

achieved, in which the ammonia to be removed mixture of ammonia crude

for the simultaneous removal of hydrogen sulfide water (condensate) and am-

fes used, the refrigerated and de-tarU; Raw gas from waste water containing monia

bottom up through a ground-level gas wash to the third washing level about 0.85 l / Nm ^{: |} Raw gas

Scher and its top washing stage with the 5 _{Enls acidified} circulating water

During the previous cooling of the gas, _the scrubbing stage ... about 0.7 1 / Nm = 'raw gas is used to coat the ammonia-raw water condensate. The

The method according to the invention is thereby the soft point of the two method variants for the label, that you get the drainage water from this (third turn, should - as already said - in erten) Washing stage on top of the lowest (first) io ster line from an economic point of view from washing stage gives up, while the middle (second) will be pending, with prices for the generated am-washing stage with deacidified circulating water operating sulphate, for the generated and used sulfur where the first and second washing acid and the cost of steam are the deciding factors accruing run-off water should be separated from one with soil-silting factors.

are supplied to the stripping column provided, 15 The method of operation according to the invention should be based on hand in such a way that the flow diagram shown in the figure in the first wash still The level that occurs in relation to the air monia content is explained in more detail. This flow sheet contains Ab- for a better overview only those for the implementation running water in the upper part of the stripping column of the process according to the invention essential Eineineleitei is, while one is relatively with less 20 directions; Ancillary facilities, such as heat exchangers Circuit water of the shearers, pumps, etc., loaded with constituents, are therefore not listed, second scrubbing stage the lower part of the aborter- likewise sind.alle upstream and downstream columns in the gas path supplied and, after at least partial removal of facilities, omitted, acidification back into the second scrubbing stage - the cooled and tarred raw gas passes through pumps, and that one from the three-stage gas washer 25 the line 1 from below into the three-stage gas scrubber escaping gas in a downstream washer 2. its individual stages through the separating shear With water or acidic ammonium sulphate solution, walls 3 and 4 are gas-permeable, but liquid-tight treated. are separated from each other. At the head of the gas

The shear emerging from the three-stage gas scrubber is discharged through line S

Gas still has a residual ammonia content of about 30 hours cooling of the gas accumulating condensate

0.8 to 1.0 gNH. / Nm ³ gas. This value must be given up (ammonia raw water). This flows on

even further down to about 0.01 gNH., / Nm ^;) Gas removed from the internals of the top (third) washing stage

be lowered. The method according to the invention descends and is carried out at the bottom of this washing stage

it allows two variants of the method to be deducted from the line 6 through which it is turned upside down

to bring about 35 the lowest (first) washing stage to achieve this goal. Here flows

pass. it also descends again on the internals and becomes

In the case of the first variant, the output from the line 7 of the abortion co-

three-stage gas scrubber escaping gas is fed in a lonne 8. This column, which is direct or in-

downstream washer with acid ammonium sulphate is heated directly with steam and the with floors 9

solution until the desired lowering of the Ammo 40 has been achieved. has the function of a combined

niakwert treated. The incurred washer-drier deacidifier. The upper part acts as a development

Solution is then in a saturator with the addition of acidic and the lower part as an aborter. The column

further ammonia to ammonium sulphate is processed in a manner known per se with steam

tet. ect or indirectly heated. Since the line 7

When using this process variant, the 45 running drainage water from the first washing stage is in the

average feed quantity of the ammonia raw water ratio to its ammonia content stronger with

on the third scrubbing stage at about 0.51 / Nm ^;) raw gas enriched with acidic components (CO. ,, H., S and HCN)

and that of the deacidified circuit water is on the chcrt, it is on the upper part (deacidifier) of the

second washing stage at about 0.91 / Nm ³ raw gas. Abortion column 8 out.

Recently, however, it has been shown that the 5 ° Das is collected at the bottom of the second washing stage.

When selling the ammonium sulphate proceeds achieved often melting circulating water, however, shows a relative

are not cost-covering. It can therefore consist of a low content of acidic components and

economic reasons make sense, on the generation is therefore through the line 10 to the lower part

of ammonium sulfate as a by-product to be completely forgiven (stripper) of column 8, in which a de-

th. 55 acidification of the circulating water takes place. At least that

The second process - partially deacidified circulating water is about eight - contributes to this point of view

Variant invoice. This is done from the three-stage floors below the inflow through line 11

Gas escaping from the gas scrubber was drawn off in one step and switched back to the second scrubbing stage Washer given with water until the lowering of the. Through line 12 steam is in the

Ammonia content to the desired end value loading 60 column 8 introduced while at the same time through the

acts. The resulting drainage water, the we line 13 water with an ammonia content of

Because of its ammonia content, about 40 mg / 1 is not released, after heat exchange and can, the ammonia raw water (condensation cooling) is repelled as waste water or other

sat) and can be widely used with this together with the third. Those in column 8 Wash stage of the gas scrubber supplied. With this Ar- 65 rising vapors, especially ammonia

Beitsweise however the amount of deacidified and hydrogen sulfide contained are due to the Reduced circulation water, so that this fol- line 14 withdrawn and in a known manner

The following mean task quantities result in: sent for further utilization.

After passing through the three-stage scrubber 2, the gas exits at the top through the line 15 and reaches the downstream scrubber 16, in which the ammonia content of the gas is to be reduced to a residual value of about 0.01 g / Nm ^{: l} gas. Depending on the mode of operation, acidic ammonium sulfate solution or water is added through line 17. The cleaned gas leaves the washer 16 through the line 18, through which it reaches the benzene washer, which is no longer shown, for the purpose of further cleaning. The ammonia-enriched washing solution flows through line 19 from the washer 16. If acidic ammonia solution was used as the washing solution, the three-way valve 20 is set so that the flowing solution passes through line 21 to the saturator 22, in which, with the addition of more ammonia, before the ammonium sulfate is precipitated and withdrawn from the process at 24.

If, on the other hand, the washer 16 is operated with water, the three-way valve 20 is set so that the drainage water flowing off through the line 19 arrives in the line 25, which in turn enters the line 5 flows out. This means that the drainage water with the

ίο ammonia raw water (condensate) combined and fed to the third washing stage of the gas scrubber 2. Finally, the method of operation according to the invention will be demonstrated using two examples, each of which ^{relates to the purification of 1000 Nm '1} in the raw gas.

example 1

relates to the method in which the washer 16 is operated with acidic ammonium sulfate solution and the process that is running Washing solution is processed further in the saturator 22 to form ammonium sulfate. Table 1 gives the gas composition in the various stages of the process, while Table 2 shows the composition the individual process water concerns.

Table 1

NH, H ₂ S
g / Nm » HCN CO ₂
Volume percentage Raw gas upstream of the scrubber 2
Gas after the first washing stage
Gas after the second washing stage
Gas after the third washing stage
Gas after the washer 16 8.0
3.5
3.5
1.0
0.01 10.0
7.0
2.0
1.0
1.0 1.5
1.1
0.4
0.3
0.3 2.5

Table 2

NH ₃ H ₁ S

HCN

CO,

NHj raw water in line 5

NHJ raw water in line 6

NH ₃ raw water in line 7

Deacidified circuit water in line 11

Enriched circuit water in line 10 ..

3.5

8.5

17.5

20.0

20.0 0.6
2.6
8.6
2.5
8.1

0.1
0.3
1.1
0.6
1.4

2.5
3.5
6.2
2.6
6.0

0.5
0.5
0.5
0.9
0.9

Example 2

deals with the process in which the washer 16 is operated with water and the drain water together is fed to the third washing stage of the gas scrubber 2 with the raw ammonia water. Table 3 gives again shows the gas composition at the various points in the process, while Table 4 shows the Composition of the individual process water concerns.

table

NH, H ₁ S
g / Nm » HCN ; CO,
Volume percentage Rohfias in front of the washer2 8.0
3.0
3.5
0.8
0.01 10.0
6.0
2.5
1.2
1.0 1.5
1.0
0.5
0.4
0.3 2.5 Gas after the first washing stage Gas after second wash Gas after the third washing stage - Gas after the washer 16

3092

Table 4

NH,

HCN

CO ₁

Fresh water in front of the washer 16

Drain through line 25

Inlet through line 5

Process through line 6

Process through line 7

Deacidified circuit water in line 11

Enriched circuit water in line 20 ..

0.0

2.3

3.0

6.2

12.1

19.8

19.1

0.0 0.6 0.6 2.1 6.8 2.3 7.3

0.0
0.3
0.2
0.3
0.9
0.6
1.3

0.0 1.5 2.1 3.0 5.0 2.6 6.0

0.35 0.35 0.85 0.85 0.85 0.70 0.70

1 sheet of drawings

309616/263

3092

Claims (5)

Claims: * ^ e present invention relates to a method for cleaning coke oven raw gases according to the prin- 1. Process for cleaning coking plant raw zip the ammonia cycle wash, whereby the degassing according to the principle of ammonia circuit - removing ammonia for simultaneous removal washing in which the ammo 5 of the hydrogen sulfide to be removed is used. niak for the simultaneous removal of the sulfur. Hydrogen is used, the cooled and tarred so that the raw gas first passes in a so-called raw gas from bottom to top through a multiple hydrogen sulfide scrubber using a stage gas scrubber and the uppermost ammonia-containing washing water from the main washing stage with that of the previous cooling io amount of the Hydrogen sulphide is freed, whereby the raw water condensate produced by the gas sends the ammonia-containing washing water after the abortion, characterized in that the water from this (third) washing (deacidification) is returned to the water sulphide at the top of the lowest ( First) scrubber "is returned. The degassed in the raw gas, while the middle (second) 15 held ammonia is in this process in the scrubbing stage with deacidified circulating water in one of the hydrogen sulfide scrubber, the in the first and second kills Washer washed out with water, this washing stage draining water obtained separately washing water then being carried in a stripper from the stripping column provided with bottoms and the ammonia taken at the same time, in such a way that the hydrogen sulfide and CO ₂ washed out in ao are freed The vapors from the deacidifier (waste water enriched with hydrogen sulphide in the upper driver) and from the ammonia stripper are introduced into the stripping column, wäh - Generally put into a saturator, in which the circulating water of the second sulphate, which is relatively less acidic with the help of sulfuric acid, is converted into ammonia to ammont parts. The scrubbing stage emerging from the saturator feeds gases which contain a great deal of hydrogen sulfide to the lower part of the stripping code and, after at least partial removal, can advantageously be worked up to sulfuric acid and returned to the second scrubbing stage. pumps, and that the three-stage 30 from German Patent 351633 is also Gas scrubber (2) leaking gas is known in a subsequent process in which the two sulfur switches Washer (16) with water or acidic hydrogen washer with the ammonia from the ammonium sulfate solution treated. condensate obtained from the driver. the 2. The method according to claim 1, characterized in that the washing water running off from the three-stage gas 35 shear is scrubber (2) escaping gas in the downstream jointly withdrawn and initially a deacidifier scrubber (16) with acidic Ammonia sulfate solution is added and then the ammonia expeller is dealt with until the ammonia content of the gas is discharged to a value of about 0.01 g / Nm ³ gas for the purpose of obtaining the ammonia-containing condensate. is sunken, whereby the resulting, with Am- 4 ° From the journal »Chemische Technik«, Vol. 2, monia-laden washing solution in a saturator No. 9, p. 300, it is also known in one of the- (22) with the addition of more ammonia to-like process in which the ammonium sulfate to be removed is further processed. moniak for the simultaneous removal of the sulfur 3. The method according to claim 1 or 2, characterized in that hydrogen is used, a multi-stage weighing system indicates that the average feed amount 45 shear to be used. The topmost wash of the ammonia raw water on the third wash stage of the washer fulfills two functions, namely the stage at around 0.51 / Nm ^s raw gas and the treatment of the gas with the circulating water acidified in the pre-cooling stage on the second wash - recovered ammonia raw water from the middle of the stage is around 0.91 / Nm ³ raw gas. Washing stage off and the post-washing of the gas with 4. The method according to claim 1, characterized ge 5 ° fresh water in the upper part of this washing stage,
indicates that the gas from the three-stage gas is The disadvantage of the known working methods is in the washer (2) escaping gas in the downstream its relatively high steam consumption to the deacidifier (16) is treated with water until the tion and the expulsion of the ammonia. As a result, the ammonia content of the gas is heavily burdened up to a value on the economic viability of this process, from about 0.01g / Nm ^s gas, where 55 is especially when there is no cheap vapor for the gas, laden with ammonia drainage. water (about 0.351 / Nm ^s gas) the ammonia The present invention therefore aims to Raw water added and together with this to keep the steam consumption as low as possible and the third washing stage of the gas scrubber (2) thus increases the efficiency of the purification of coke will. 60 to improve rei raw gases. To achieve this goal 5. The method as claimed in claim 4, characterized in that the detergent should be as small as possible, so that the average feed amount is used, which in the sulfur water mixture of raw ammonia water and hydrogen leaching has a high level of selectivity and, in the case of waste water containing ammonia, the third ammonia leaching a high intensity cr scrubbing stage at about 0.851 / Nm ^s raw gas and the 65 calls. of the deacidified circulating water to the second Washing stage is about 0.7 1 / Nm ³ raw gas. Appropriate procedures for cleaning raw coking gas sen according to the principle of the ammonia cycle scrubbing