Verfahren zur Regelung der Konzentration der nach dem Verfahren der adiabatischen Chlorwasserstoff-Absorption gewonnenen Salzsaeure

摘要

In the manufacture of hydrochloric acid by the adiabatic absorption in water of a fluctuating supply of impure hydrogen chloride, the concentration of the effluent acid is maintained constant by controlling the water supply in response to said concentration whereby the temperature of the adsorption zone is sufficiently high to entrain impurities in the steam produced. Should the hydrogen chloride concentration decrease, the water supply is increased to form a dilute acid which is withdrawn, stored and fed instead of water in an ensuing period of high hydrogen chloride concentration in the feed gas. The working temperature is preferably 80-100 DEG C. As shown in Fig. 1, hydrogen chloride containing gas passes through pipe 1 into absorption packing 3. When the amount of hydrogen chloride gas is insufficient for the working temperature to be reached, absorption water is supplied through pipe 4, controlled by valve 26, from tank 14. The water level in tank 14 is kept constant. The hydrochloric acid formed passes through into pipe 7, where its electrical conductivity is measured by 8, overflows at 9, passes through gas seal 10, cooler 11, by-passing closed valve 23 and is stored in container 13. When the rate of supply of hydrogen chloride gas is high enough for sufficient heat to be generated by absorption for enough water to evaporate to create a temperature of 80-100 DEG C. at temperature sensing device 16, temperature regulator 27 firstly switches on concentration regulator 29 which now controls the amount of absorption liquid supplied to the absorption tower, secondly opens valve 23 so that pure acid flows into a reservoir (not shown), and thirdly causes contaminated hydrochloric acid to be pumped from tank 13 into tank 14 after a selected lapse of time, which closes valve 25 to stop the flow of water. The level in the tank is controlled by overflow 20. The contaminated hydrochloric acid is now supplied to the absorption tower, and when tank 14 is empty, valve 25 opens and water is again fed in. If the supply rate of hydrogen chloride falls below a certain minimum determined by the flow of water and the size of the column, flow regulator 32 restores the control of the flow of water to remote control 21 and closes valve 23, whereby contaminated acid is again collected in container 13.