In the past few years, the main production metho […]
In the past few years, the main production method of hydrochloric acid was to absorb by-product hydrogen chloride by water. This is not only a part of the circular economy, but also an effective measure for enterprises to improve economic efficiency and reduce production costs. Below we briefly introduce the industrial by-product acid extraction method.
With the gradual popularization of the hydrochloric acid desorption method, the process of producing hydrogen chloride by by-product acid desorption has been widely used in production. It is a by-product hydrogen chloride which is absorbed by the dilute acid in the absorption of organic chloride in the adiabatic absorption tower. After concentration, it enters the desorption column to decompose high-concentration hydrogen chloride gas. The purity of the hydrogen chloride gas produced by this method is above 99.99~(mass fraction).
The process is as follows: the by-product hydrogen chloride is countercurrently contacted with 20% dilute hydrochloric acid sent by the dilute acid pump through the packed adiabatic absorption tower, and the by-product hydrogen chloride is made into hydrochloric acid by adiabatic absorption. More than 31% of concentrated acid can be obtained from the bottom of the tower, and the dilute acid is preheated by the graphite heat exchanger and then sent to the concentrated acid tank, and sent to the packed or plate type desorption tower by the concentrated acid pump.
The material discharged from the bottom of the desorption tower is heated by the externally introduced steam by means of a reboiler connected thereto, so that hydrogen chloride and a small amount of water vapor are evaporated to exchange heat and mass with concentrated hydrochloric acid flowing downward from the top of the column, and the acid is exchanged. The hydrogen chloride gas is desorbed. The hydrogen chloride gas is cooled from the top of the graphite into the graphite primary cooler and cooled to room temperature, then enters the graphite secondary cooler, cooled to 12-18 ℃ with chilled brine, and the entrained acid is removed by an acid mist trap. fog.
The dilute acid coming out from the bottom of the analytical column is an azeotrope of hydrogen chloride and water with a volume fraction of 20%-22%. After heat exchange with a dilute acid cooler or concentrated acid, it is cooled to below 40 ℃ and enters the dilute acid The acid is pumped by a dilute acid to absorb the absorption tower to obtain concentrated acid.