SU1583351A1 - Method of producing sulfuric acid - Google Patents

Abstract

The invention relates to the production of sulfuric acid by a contact method using technical sulfur as a raw material, and can be used in the chemical industry and allows an increase in the yield of the product by reducing the loss of sulfur with sludge. Sulfuric acid is obtained by multistep oxidation of sulfuric anhydride to sulfuric acid with intermediate absorption of the latter to form sulfuric acid and gas separation after the first oxidation stage into two streams. At the same time, one of the gas streams, along with a stream of hot air, is directed above a layer of sulfur slurry at 430-520 ° C at a speed of 1300-1600 nm 3 / h per 1 m 2, which is a waste product of sulfuric acid production. The volume ratio of sulfuric anhydride and oxygen in the gas mixture is (6.9-5.2): (10.9-13.4), respectively, and the temperature and speed are sufficient to ignite the sulfur slurry and maintain the stability of the formation of sulfuric anhydride. At this time, another separated gas stream is cooled to a temperature sufficient to conduct intermediate absorption, which is carried out after mixing the streams before being fed to the next oxidation step. 1 tab., 1 Il.

Description

The invention relates to the production of sulfuric acid by a contact method using technical sulfur as a raw material and can be used in the chemical industry.

The aim of the invention is to increase the yield of the product by reducing the loss of sulfur from the sludge.

In the process involving the multistep oxidation of sulfur dioxide to sulfur with intermediate absorption of the latter with the formation of sulfur

acid and gas separation after the first stage of oxidation into two streams, followed by their mixing before feeding to the next oxidation stage, one of the gas streams along with a stream of hot air is directed above a layer of sulfur slurry - waste sulfuric acid, in a volume ratio of sulfuric anhydride: oxygen in the gas mixture 6.9 - 5.2: 10.9 - 13.4, respectively, at 430 - 520 ° C at a rate of 1300 315

1600 nmE / h per 1 MJ, and the other gas stream is cooled to a temperature sufficient to perform intermediate absorption, which is carried out after mixing the streams before being fed to the next oxidation stage. The speed of 1300-1600 Nm3 / h on

The 1m surface of the sludge sludge and the temperature of the gas stream 430-520 C Q allow for the self-ignition of the sludge sludge and stable formation reactions of the sulfurous anhydride without additional maintenance of the temperature of the atura.

The drawing shows a scheme implementing the method.

Example. Pipeline 1 is pumped into the dryer at 287550 Nm3 / h previously cleaned from dust 20

Atmospheric air with a temperature of 20 ° С, dried with 94-95% sulfuric acid with a temperature of 65 ° С. Through the drip tray 3 through the duct 4 dried air with a temperature of 70 ° C 25 and under a pressure of 2300 nm of water. heated in heat exchangers 5–9 to a temperature of 416 ° C, are directed along a gas line 10 to a cyclone furnace 11, providing a SO: 07 ratio of 6.9: 10.9 at a speed of 1600 per 1 m 2 of surface sulfur slurry and jointly passed over a layer of sulfur slurry. When this occurs, the upper layers of the sludge are self-igniting, as a result of which the sulfur burns in accordance with the chemical reactions:

S +

ABOUT,

+ 2SO u

SO,

3SOa

Since a large amount of heat is generated as a result of combustion, the lower layers of sulfur slurry are heated, where, when the temperature reaches 444 ° C, sulfur sublimation occurs, which accelerates the processes of its combustion in the sulfur flame. The process lasts until complete burnout of sulfur, i.e. periodic. The resulting gas mixture enters the gas duct 24 and then with the main flow into the mixer 23, where after mixing two streams, gases with a temperature of 200 ° C flow into the intermediate absorber in the amount of 10,110 kg / h Q ber 27, which is irrigated with 98.3%

liquid sulfur, where it burns to form 10.4% by volume SO3 at 1200 ° C. Gas from the cyclone furnace in the amount of 97600 Nm3 / h is cooled in the evaporation unit 12 to 420 C and fed through the duct 13 to the first contact shelf 14 of the contact apparatus 15, and then through the heat exchanger 16 to the second and through the heat exchanger 9 to the third contact shelves, Gases after the first stage of contact at 465 ° C in the amount of 97600 nm / h and the degree of contact, 94% through the duct 17 leave the contact apparatus 15 and are divided into two streams. One gas stream in the amount of 71600 Nm3 / h is directed along. gas duct 18 for cooling to heat exchangers 19, 20, 5 to a temperature of 200 ° C, then to intermediate absorber 21, which is irrigated with 24% oleum at 556С, and through gas duct 22 to mixer 23. The second gas flow is in the amount of 26000 nm A.h. through the duct 24 is sent to the mixer 23. A part of this gas flow 1070 Nm3 / h is sent along the bypass 25, into which air is fed through the duct 26 in an amount of 530 with a temperature of 41 6 ° C,

sulfuric acid at 70 ° C. The degree of absorption SOj 99.9%.

Gases after absorber 27 in the amount of 71550 nm / h with a temperature of 75 °

e, through the flue 28, heat exchangers 19, 20, 16 are heated where they are heated to 430 ° C, after which they are transferred to the second stage of contact, to the contact shelf 29. After the contact apparatus 15, gases with a total degree of contact of 99.5% the flue 30 is fed to the cooling in the heat exchangers 8, 7, the bis temperature of 200 C is fed to the final

45 absorber 31, which sprays 98.3% sulfuric acid at 70 ° C, after the absorber 31 gases with a concentration of sulfur-containing, not exceeding the maximum permissible concentration, in 58000 Nm3 / h at temperatures

40

50

55

75 C are emitted to the atmosphere.

.

The results of the experiments are given in that person.

As can be seen from the data table, when the gas flow rate

over a layer of sulfur slurry less than 1300 nm / h on 1 surface of chamois

providing the ratio of SO: 07, equal to 6.9: 10.9, with a speed of 1600 per 1 m 2 of the surface of the sulfur slurry and together pass over the layer of sulfur slurry. When this happens, self-ignition of the upper layers of sulfuric sludge occurs, as a result of which sulfur burns in accordance with chemical reactions:

+

ABOUT,

+ 2SO u

SO,

3SOa

Since a large amount of heat is released as a result of the combustion of sulfur, the lower layers of sulfuric sludge are heated, where the sublimation of sulfur occurs when the temperature reaches 444 ° C, which accelerates the processes of its combustion in the sulfur flame. The process lasts until complete burnout of sulfur, i.e. periodic. The resulting gas mixture enters the gas duct 24 and then with the main flow into the mixer 23, where after mixing the two streams, gases with a temperature of 200 ° C flow into the intermediate absorber 27, which is irrigated at 98.3%

sulfuric acid at 70 ° C. The degree of absorption SOj 99.9%.

Gases after the absorber 27 in the amount of 71550 nm / h with a temperature of 75 ° C

through the duct 28 are sent to heat exchangers 19, 20, 16 where they are heated to a temperature of 430 ° C, after which they enter the second stage of contact, to the contact shelf 29. After the contact apparatus 15, gases with a total degree of contact are 99.5% through the duct 30 arrive at cooling in heat exchangers 8, 7, bis with a temperature of 200 ° C arrive at the final

the absorber 31, which sprinkles with 98.3% sulfuric acid at 70 ° C, after the absorber 31 gases with a concentration of sulfur-containing, not exceeding the maximum permissible concentration, in the amount of 58,000 Nm3 / h at a temperature

75 C are emitted to the atmosphere.

.

The results of the experiments are given in the table.

As can be seen from the data in the table, when the gas flow rate

over the layer of sulfur slurry less than 1300 nm / h on 1 surface of the sulfur slurry and the volume ratio S03: -: 0-g in the gas mixture over 6.9: 10.9, the time of sulfur burnout increases, i.e. the time during which there is no periodic reduction of the newly formed sulfuric sludge in the continuous process of producing sulfuric acid, which leads to an imbalance in the material balance of the use of the sludge.

With a gas flow rate of more than 1600 nme / h per 1 m 9 of the surface of the sludge, dusting increases, which is dispersed solid residues of the sludge after burning sulfur out of it, which leads to a decrease in the quality of sulfuric acid due to their ingress.

When the volume ratio SOj: 0 in the gas phase is less than 5.2: 13.4, the overall degree of contact in the contact apparatus decreases in connection with increased air extraction, which increases the loss of sulfur-containing substances as they are released into the atmosphere.

Claims (1)

The application of the proposed method in comparison with the known allows to increase the yield of the final product by 0.32% in connection with the use of sulfuric gallam sulfuric acid production waste, which contributes to the improvement of environmental protection. Invention Formula The method of producing sulfuric acid, including the multi-stage oxidation of sulfur dioxide obtained by burning sulfur, the separation of gas after the first oxidation stage into two streams, one of which is directed to intermediate absorption, followed by mixing them before the second oxidation stage, cooling the gas and sulfur trioxide absorption after each oxidation stage, differently in order to increase the product yield beyond by reducing sulfur losses with sludge obtained when burning it, after separation, the second gas stream is passed in a mixture with air at a volume ratio of sulfur trioxide to oxygen of 6.9 -: 10.9 - 13.4 respectively a layer of sulfur slurry at a temperature of 430 - 520 ° C at a speed of 1300 - 1600 nme / h per 1 m 2 of the surface of the slurry, and then mixed with the first stream that passed the intermediate absorption, and the mixture before feeding to the second oxidation stage is directed to additional absorption. 99.5 991.5 99.5 99.5 99.5 99.5 99.5 99.5 99.5 99.5 99.5 99.5 99.45 99.42 99.33 99.30 J