SU1152929A1 - Method of concentrating sulfuric acid - Google Patents

Abstract

METHOD OF CONCENTRATING SULFURIC ACID INTO several I - v-v ,. 1 | , -: p-zo-. I -, -. iX.-r;:. .-a t -.-.- a; i LTHOTYED stages by direct contact with the heat-transfer gas in countercurrent mode with separate flow of heat-transfer gas by parallel streams at a stage, characterized in that, in order to reduce the loss of sulfuric acid by reducing fogging and intensifying the process, the heat transfer gas supplied to the last concentration stage is pre-mixed with air in a ratio of 0.24-4 hours of air for 1 hour of gas and the temperature of the mixture is maintained at 200700 ° C below the temperature of the heat carrier gas, given to the penultimate stage.

Description

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The invention relates to methods for the concentration of sulfuric acid and can be used for the concentration of other inorganic acids.

The purpose of the invention is to reduce the loss of sulfuric acid by reducing fogging and intensifying the process.

The essence of the method is that when concentrating sulfuric acid in several stages by direct contact of the heat-transfer gas with the acid in countercurrent mode with separate flow of the heat-transfer gas in parallel streams at the heat-transfer gas stage supplied to the last acid concentration step, it is pre-mixed with air in the ratio of 0.25-4 hours of air for 1 hour of the heat carrier gas and the temperature of this mixture is maintained 200-700 ° C below the temperature of the heat carrier gas supplied to the penultimate stage acid concentration.

Example 1. Sulfuric acid with a temperature of 120 ° C in an amount of 10,650 kg / h enters the concentrator divided into several chambers. In the penultimate stage, the concentration is supplied with heat-transfer gas with a temperature of 800 ° C in an amount of 10,000. At the last stage, a mixture of 2000 gas with a temperature of 900 ° C and 500 atmospheric air is supplied. The temperature of the mixture of gas with air is 700 ° C (200 ° C lower than the gas temperature at the penultimate stage). The proportion of air in the mixture is 0.25 h for 1 h of the heat transfer gas. A 92.5% acid with a temperature of 225 ° C flows out of the concentrator. The loss of acid from the exhaust gases after the electrostatic precipitator is 0.3 kg / ton of acid produced.

Example 2. The concentrator, divided into several chambers, receives sulfuric acid with a concentration of 68% with a temperature of 120 ° C in an amount of 13,500 kg / h. At the penultimate stage of concentration, a heat carrier gas is supplied with a temperature of 1000 ° C in an amount of 10,000. 1250 air and 1250 nm3 / h of heat carrier gas are supplied to the last stage. The temperature of the mixture is 500 ° C (500 ° C (lower than the heat carrier gas in the penultimate stage). The proportion of air in the mixture is 1 hour for 1 hour of heat carrier gas. 92.5% acid flows from the concentrator with a temperature of 215 ° C. The loss of acid from the exhaust gases after the electrostatic precipitator is 0.1 kg / ton.

Example 3. A 68% concentration of sulfuric acid is supplied to a concentrator separated by several chambers with a temperature of

120 ° C in an amount of 14,100 kg / h. At the penultimate stage of concentration, a heat carrier gas is supplied with a temperature of 1100 ° C in an amount of 10,000. At the last stage, a mixture of 500 nm / h (gas a-tep0 carrier with a temperature of 1100 ° C and 12000 air heated to 230 ° C is supplied. The temperature of the mixture is 400 ° C (which is 700 ° C lower than the heat-transfer gas on the last but one stage). The proportion of air in the mixture is 4 hours for 1 hour of heat carrier gas). A 92.5% acid with a temperature of 220 ° C flows out of the concentrator. The loss of acid from the exhaust gases after the electrostatic precipitator is 0.8 kg / ton acid.

Reducing the temperature difference between the gases at the last and the penultimate stages of concentration (less than 200 ° C) and the proportion of injected air in the heat-transfer gas (less than 0.25 nm of air per 1 nm of gas) is impractical due to the increase in losses

5 sulfuric acid with fog.

Exceeding the upper limit of the temperature difference (more than 700 ° C) and the proportion of air concentration introduced at the last stage will lead to an increase in the intensity of the process, however, there will be a simultaneous increase in the loss of sulfuric acid with fog.

Claims (1)

METHOD FOR CONCENTRATION OF SULFURIC ACID in several stages by direct contact with a heat carrier gas in countercurrent mode with separate supply of heat carrier gas in parallel flows at a stage, characterized in that, in order to reduce sulfuric acid losses by reducing fogging and intensifying the process, gas the coolant supplied to the last stage of concentration is pre-mixed with air in a ratio of 0.24-4 hours of air per 1 hour of gas and the temperature of the mixture is maintained at 200700 ° C below the temperature ry coolant gas supplied to the penultimate stage. SI u s u s u