DE2335558A1 - METHOD AND APPARATUS FOR THE PRODUCTION OF SULFUR ACID - Google Patents

Description

The invention relates to a process for the production of sulfuric acid in which gases containing sulfur dioxide are present a catalyst are oxidized, the sulfur trioxide formed in an intermediate absorption tower with the formation of Sulfuric acid is absorbed, the remaining gases a subjected to further oxidation in the presence of a catalyst and thus formed further sulfur trioxide in one Final absorption tower is absorbed with the formation of sulfuric acid. Such a process is called the intermediate absorption process designated.

0988 5/1085

In this process, they usually become the intermediate absorption tower leaving gases heated by heat exchange to their temperature at a suitable high level for to increase the second oxidation step. The procedure points a significant disadvantage in that acid vapors and mists from the intermediate absorption tower with the gases can be transported. This causes severe corrosion on the heat exchangers.

The invention is directed to a process for the production of sulfuric acid, by means of which the disadvantages mentioned are avoided can be.

According to the invention, this object is achieved by a method of the type mentioned at the outset, in which two sulfur dioxide gullies be used, which contain the gases at high or low temperatures, with the source at low temperature is introduced into the intermediate absorption tower via a catalytic system and that coming from the intermediate absorption tower Remainder of the same mixed with the high temperature source is added to the final absorption tower via another catalytic system to be introduced, and with no heat exchange means between the intermediate absorption tower and the further catalytic system is provided.

The invention is also directed to a device or system for carrying out the above method.

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The invention is explained in more detail in the following description, reference being made to the drawing, which in exemplary form a flow diagram of an embodiment of the apparatus for carrying out the method of the invention shows.

According to the drawing, the device essentially comprises an air drying tower 10, a sulfur burner 11, a converter 12 having a plurality of catalyst beds, an intermediate absorption tower 13 and a final absorption tower 14..

Air is introduced at the bottom of the drying tower 10. The air is compressed (packed) in a known manner via a line 15 in order to be passed in the upward direction through the tower, specifically in countercurrent to the sulfuric acid which is introduced at the top of the tower via a line 16. The dry air leaves the tower 10 via a line 17 and is passed on to the sulfur burner 11. In the air supplied via line 17, liquid sulfur is burned to obtain a composite gas mixture containing sulfur dioxide, oxygen and nitrogen. A portion of this composite gas mixture leaves the sulfur burner 11 via a line 18 and has a high temperature of the order of magnitude of 1000 ^° C. or more. The remainder of this 2. usar.i; 7iengeset2-th gas mixture leaves the sulfur burner 11 via a line Λ-) after passing through a waste heat boiler

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and has a temperature in the order of 380 ⁰ C. This cooler composite gas mixture is introduced into the top of the converter 12 via line 19 to flow over a first catalytic bed 12a. The reaction that takes place on the catalytic bed 12a is the combination of sulfur dioxide with oxygen to form sulfur trioxide. This reaction is exothermic. The gases leaving bed 12a are cooled in a heat exchanger 21 before being passed to a second catalytic bed 12b to allow the reaction to continue. The gases leaving the bed 12b, consisting essentially of sulfur trioxide, sulfur dioxide, oxygen and nitrogen, have a temperature of the order of 480 ° C. and are passed through a line 22 via a heat exchanger 23 which brings them to a temperature of the order of 200 ° C cools, introduced at the foot of the intermediate absorption tower 13. Sulfuric acid coming from a conduit 24 is sprayed downwardly through the tower 13 which is packed or sealed in a known manner to absorb the sulfur trioxide in a known manner. The remainder of the gas stream exiting tower 13 via line 25 at a temperature of approximately 70 C is mixed with the high temperature composite stream exiting sulfur burner 11 via line 18 to give a combined stream which has a temperature of the order of 380 ° C. and is passed via a line 26 to a third catalytic bed 12c in the converter 12 in order to

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to form teres sulfur trioxide. The gases leaving the bed 12c via a line 27 are heated by means of a heat exchanger, e.g. a waste heat boiler 28, before being returned to the tower 12 to pass through a fourth catalytic To flow bed 12d for further oxidation of sulfur dioxide. The gas stream exiting catalytic bed 12d is conducted via a line 29 to the base of the final absorption tower 14 via a heat exchanger 30. The gases flow in the upward direction through the tower 14, which is packed or sealed in a known manner, in countercurrent to sulfuric acid, which is introduced at the top of the tower via a line 31 to absorb the sulfur trioxide. That head The exhaust gas leaving the tower 14 consists essentially of oxygen and nitrogen as well as residual sulfur dioxide. It is blown into the atmosphere by means of an exhaust chimney 20.

It is understood that the are diluted from the feet of the towers 10 and 14 collected acid streams to the extent necessary to add the product to give sulfuric acid and provide the required for the process of sulfuric acid, which is introduced these towers in öede * ^1.

The catalyst used in the converter 12 is selected to facilitate the reaction in the temperature ranges given above supports. Typically, a vanadium pentoxide based catalyst is used.

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Typical conditions for carrying out the process described above are given in the following examples.

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EXAMPLE I

In this example, the situation is considered in which the sulfur burner 11 is operated so that the gases delivered by it 11 contain volume -? *) Sulfur dioxide.

^ X _n POSITION
ANALYSIS\
Vol. -96 \ sulfur
burner 11 Exit-
Waste heat boiler
Line 19 Exit 2.
converter
passage
Management 2.2 Heating gas
current
Line 18 Entrance 3
converter
passage
Line 26 (. »■» ■■ rmimini »
Exit 4.
converter
passage
Line 29 SO ₂
O ₂
SO ₃
N ₂ . 11
10
79 11
10
79 1.2
5.1
9.8
83.9 11
10
79 4.6
7.3
88.1 0.1
5.2
4.6
90.1 ⁰ C
Total-
conversion % 1050 ° 380 ° 516 ° 1050 ° 380 ° 436 °
99.2 total
volume 100 70 30th
r, r-itrimr amiiiKOiim. '■ ti -

cn αϊ cn 00

EXAMPLE II

O (O CD

In this example, the situation is considered in which the sulfur burner 11 is operated in this way is that the gas streams originating from it contain 12% by volume of sulfur dioxide.

\POSITION
AnalvseV
Voi .-% \ ^ sulfur
burner 11 exit
Waste heat boiler
Line 19 Exit 2.
converter
passage
Line 22 Heating gas
current
Line 18 I.
Entrance 3
converter
passage
Line 26 Exit 4.
converter
passage
Line 29 SO ₂
° 2
SO ₃
N ₂ 12th
9
79 12th
9
79 1.9
4.1
10.8
33.2 12th
9.
79 5.2
6.0
88.8 0.1
3.6
5.2
90.1 ⁰ C
total
conversion% 1100 ° 380 ° 526 °
39 1100 ° 380 ° 443 °
99.2 total
volume 100 72 - 28 - -

cn cn cn co

Claims (4)

Claims (T) Process for the production of sulfuric acid, in which gases containing sulfur dioxide in the presence of a catalyst are oxidized, the sulfur trioxide formed is absorbed in an intermediate absorption tower with the formation of sulfuric acid the remaining gases are subjected to further oxidation in the presence of a catalyst and further sulfur trioxide thus formed is absorbed in a final absorption tower with the formation of sulfuric acid, characterized in that two sulfur dioxide sources are used, which the gases at high resp. contain low temperatures, with the source with low temperature via a catalytic system in the intermediate absorption tower is introduced, and the remainder of the same coming from the intermediate absorption tower with the source high temperature is mixed to be introduced into the final absorption tower via a further catalytic system and there is no heat exchange means between the intermediate absorption tower and the further catalytic one System is provided. 2. The method according to claim 1, characterized in that the sources for the sulfur dioxide Derive gases from a sulfur burner. 3 09885/1085 233bb58 3. The method according to claim 1 or 2, characterized in that the sulfur dioxide-containing gases have temperatures in the order of magnitude of 1100 ⁰ C or 375 ° C. 4. Device for performing the method according to one of claims 1 to 3, characterized through facilities to provide two sources of sulfur dioxide with high or low temperatures ,, lines to Introducing the low temperature sources through a first catalytic system into an intermediate absorption tower and Lines for introducing the orption tower with the intermediate absorption tower coming remainder of the source at low temperature mixed source at high temperature over a second catalytic system, with no heat exchange means between the intermediate absorption tower and the second catalytic system are provided. - 10 - 309885/1 085