DE2410411C2 - Process for the elimination of ammonia, in particular coking ammonia - Google Patents

Description

The invention relates to a method for removing ammonia, in particular coking ammonia, by burning the ammonia vapors expelled with water vapor in the presence of air.

It is known that the ammonia contained in it must be removed from the coke oven gas, since the same in interaction with the other accompanying substances of the coke oven gas causes corrosion in the pipelines and equipment.

Various methods are therefore already available for removing the ammonia from the coke oven gas been applied. For example, the coke oven gas can be passed through a saturator in which the Ammonia in the gas is converted into ammonium sulfate by means of sulfuric acid and then this is crystallized from the solution.

In another method, the coke oven gas is washed in an absorption tower (scrubber) with a suitable scrubbing liquid that dissolves the ammonia and removed from the gas. A particularly suitable washing liquid in this process is water used, the ammonia from the laden with ammonia water by simple distillation with Water vapor can be driven off. The resulting ammonia vapors can either Ammonium sulphate are converted, but they can also be converted to strong ammonia water or to compressed water Ammonia are worked up.

For the products just mentioned, however, the sales opportunities have increased in recent years has deteriorated very much, and it is hardly possible today to sell these products at a price which Manufacturing costs have therefore been increasing in recent times Use has been made of the method known for several decades, the ammonia vapor in the presence of air to burn. In addition to nitrogen and water, nitrogen oxides are also formed, which together with the rest Components get into the atmosphere as smoke gases. The ever stricter environmental protection regulations make it necessary, however,

ίο to reduce the nitrogen oxide content of the flue gases resulting from ammonia combustion as drastically as possible.

The invention was therefore based on the object Process for the elimination of ammonia, in particular r * of coking ammonia, by burning in To develop the presence of air in which the flue gases resulting from the ammonia combustion contain as little nitrogen oxides as possible.

This goal is achieved in a method of the introduction

described type achieved according to the invention in that the ammonia vapors are initially ^{partially burned with an oxygen deficit at a temperature of 950 0} C to 1150 ⁰ C and then completely with an oxygen surplus at a temperature of 950 ⁰ C to 1050 ⁰ C are burned, the optimum combustion temperature being set in the second stage by adding recirculated flue gas accordingly and where the sensible heat of the flue gases produced during combustion is used to generate steam is used.

Further details of the method according to the invention are given below with reference to the in the figure reproduced flow charts are explained. The flow diagram only shows the explanations for the Process necessary plant parts, during ancillary facilities as well as the associated dimensional and Control systems are not shown.

The ammonia vapors intended for combustion are passed through line 1 to burner 2 fed. In order to achieve the temperature of 950 ° C to Maintain 1150 ° C and ensure stable flame formation to be able to achieve, a heating medium, such as coke oven gas, in addition, through the line 3 burner 2 are initiated. However, another heating medium such as natural gas, oil or the like can also be used can be used. The necessary combustion air is supplied via line 4 and fan 5. Lines 6, 7 and 6 branch off from line 4 8 from.

In the first combustion stage, an excess of oxygen is used. That is, through the lines 6 and 7 so much air is introduced into the burner 2 that the partial combustion of the ammonia vapor and of the heating medium in the first stage at one

Amount of oxygen takes place that is 90 to 99.9% of that for that

complete combustion of ammonia to nitrogen and water required theoretical value.

After the flames have burned out in the front part

ω of the combustion chamber 9 is still through the line 8 further air is introduced into the middle to rear part of the combustion chamber 9. Simultaneously takes place through the lines 15 and 16 nor the addition of recirculated flue gas. This is measured in this way sen that in the second combustion stage, which is at a Temperature should run between 950 ° C and 1050 ° C, the optimal combustion temperature is maintained will. Since the second combustion stage under acid

Substance surplus is to be carried out, the addition of air through line 8 and from recirculated flue gas through lines 15 and 16 can also be adjusted so that the middle and rear part of the combustion chamber 9, an amount of oxygen is supplied that is between 100.1 to 110% of that for the complete combustion of ammonia to nitrogen and water is required

Directly on the combustion chamber 9 is the waste heat boiler 10, in which the during the combustion accruing smoke. These are cooled in the waste heat boiler 10, with their sensible heat is used to generate steam. The required feed water supply to the waste heat boiler 10 takes place through line 17, while the generated steam is withdrawn through line 18. To maintain a constant boiler water quality, the waste heat boiler 10 is drained and the resulting Waste water withdrawn through line 19.

The cooled flue gases leave the waste heat boiler 10 through the line 12, in the direction of the chimney 20 reach. The smoky cookware is then released into the atmosphere. In front of the fireplace 20 branches off the Line 12, however, from line 13 through which some of the flue gases by means of the fan 14 and via the Lines 15 and 16 are fed back into the combustion chamber 9. But we have already moved on to this has been received above.

The following process example, the ammonia incineration plant a coke oven gas treatment with an output of 135 00ONmVh coke oven gas concerns, is intended to demonstrate the practical usefulness of the method according to the invention. Be there the following data is determined for the individual parts of the system:

a) Ammonia vapor through line 1:
2677 NmVh; t = 7O ⁰ C
containing: NH ₃ approx. 53.8% by volume

H ₂ S approx. 0.8% by volume
CO ₂ approx. 18.4% by volume
HCN approx. 0.2% by volume
H ₂ O approx. 26.8% by volume

b) heating medium through line 3:
400 N mJ coke oven gas / h; t = 25 ° C
containing: CO ₂ approx. 1.5% by volume

CnHm approx. 2.7% by volume
O ₂ approx. 0.5% by volume
CO approx. 6.3% by volume
H ₂ approx. 57.5% by volume
CH ₄ approx. 25.5% by volume
N ₂ approx. 6.0 VOI .-%

c) Air through line 6:
1801 NmVh; t = 25 ° C

d) Air through line 7:
4336 NmVh; t = 25 ⁰ C

e) Combustion temperature in the first combustion stage:

tO5O ° C

f) Amount of oxygen in the first combustion stage: 95% of the theoretical value

g) Air through line 8:
1700 NmVh; t = 25 ° C

h) flue gas through line 15:

9944 NmVh; t = 350 ° C
ίο i) Flue gas through line 16:

736 NmVh; t = 350 ° C

j) Combustion temperature in the second combustion stage:

1020 ° C
k) Amount of oxygen in the second combustion stage:

110% of the theoretical value
1) Flue gas temperature:

in front of the waste heat boiler 10: 1020 ° C

after the waste heat boiler 10: 350 ⁰ C
m) Total amount of flue gas:

21 828 NmVh
n) Flue gas to the chimney 20:

11 148 NmVh-t = 350 ° C

The above data show that the method according to the invention enables combustion of the ammonia resulting from the coke oven gas treatment to be carried out in such a way that the resulting and the flue gases released into the atmosphere contain very little nitrogen oxides. That Process according to the invention requires only slightly higher investment costs because of the flue gas recirculation, than is the case with other prior art methods. Opposite to these known processes, either with a large excess of air or at elevated combustion temperatures work, the method according to the invention is characterized in that the ΝΟ, output to about a third is reduced.

Of course, the applicability of the method according to the invention is not only applicable to the im

_{practically H 2} S-free ammonia vapors applied in the above process example are limited. Rather, ammonia vapors can also be used which have a considerably higher H ₂ S content and which may also come from a source other than the coke oven gas.

containing: CO ₂ approx. 6.0% by volume O ₂ approx. U vol% SO ₂ approx. 0.2% by volume N ₂ approx. 623 vol% H ₂ O approx. 30.2% by volume NO _x approx. 120 ppm ο) Saturated steam through line 18: 93 t / h; 16atu

1 sheet of drawings

Claims (4)

Patent claims: 1. A process for the removal of ammonia, in particular from Kokereiammomak, combustion of the aborted with steam Ammoniakbrüden, in the presence of air, characterized in that the Ammoniakbrüden first partially combusted with oxygen deficiency at a temperature of 950 ⁰ C to 1150 ° C and then with an excess of oxygen be completely burned at a temperature of 950 ⁰ C to 1050 ⁰ C, the optimal combustion temperature being set in the second stage by adding recirculated flue gas accordingly and the sensible heat of the flue gases resulting from the combustion being used to generate steam. 2. The method according to claim 1, characterized. that in the first combustion stage in addition, a suitable heating medium. such as coke oven gas is also burned. 3. Process according to claims 1 and 2, characterized in that the amount of oxygen in the first combustion stage 90 to 99.9% and in the second combustion stage 100.1 to 110% of the theoretical value required for combustion 4. Process according to claims 1 to 3, characterized in that the recirculated flue gas in divided several partial flows and introduced into the combustion chamber at different points.