Hydrochloric acid waste liquid regenerating method and system

Abstract

The invention relates to a hydrochloric acid waste liquid regenerating method. The method adopts a spray roasting method, and comprises the following steps that part of waste heat of circulating liquid in a first-stage washing mechanism is recycled to be used for preheating at least one part of hydrochloric acid waste liquid entering a venturi preconcentrator. The invention further relates to a hydrochloric acid waste liquid regenerating system. The hydrochloric acid waste liquid regenerating system comprises a roasting furnace, the venturi preconcentrator, an absorption tower and one or more stage washing mechanisms, which are sequentially connected through a flue gas pipeline; a heat exchanging mechanism is arranged on a circulating liquid pipeline of the first-stage washing mechanism; a refrigerant inlet of the heat exchanging mechanism is connected with a hydrochloric acid waste liquid storing tank; a refrigerant outlet is connected with the venturi preconcentrator. The hydrochloric acid waste liquid is preheated by the circulating liquid in the first-stage washing mechanism, so that the energy is saved, the consumption is reduced, and the efficiency of regenerating and recycling hydrochloric acid can be improved; besides, the circulating liquid in the first-stage washing mechanism is cooled, and the heat exchanging capacity between the low-temperature circulating liquid and flue gas is large, so that the washing effect of the first-stage washing mechanism and the absorbing effect of the absorption tower can be improved.

Description

technical field [0001] The invention relates to a hydrochloric acid waste liquid regeneration method and regeneration system. Background technique [0002] The hydrochloric acid pickling waste liquid produced by iron and steel or chemical enterprises generally uses the spray roasting method to regenerate the hydrochloric acid waste liquid, including the following steps: (1) The hydrochloric acid waste liquid directly enters the Venturi pre-concentrator to heat and concentrate, and then passes through the Venturi The circulating pump of the pre-concentrator and the feeding pump of the roaster are pressurized and sprayed into the roaster with mist droplets. After the droplets undergo a chemical reaction in the roaster, HCl, H 2 O, O 2 , CO 2 , N 2 and a small amount of Fe 2 o 3 The high-temperature flue gas of the powder (390-410°C); (2) The above-mentioned high-temperature flue gas enters the Venturi pre-concentrator to exchange heat with the hydrochloric acid waste liqu...

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Problems solved by technology

[0003] The hydrochloric acid waste liquid enters the Venturi pre-concentrator for heating and concentration, and sprays it into the roaster for chemical reaction after reaching a certain concentration. This process requires a lot of heat to be realized; this part of the heat is mainly provided by the roaster system. It takes a lot of fuel to realize it, which does not meet the requirements of energy saving and consumption reduction

However, the temperature of the mixed flue gas discharged from the roaster and Venturi pre-concentrator is still as high as 95-100°C. After conventional cooling and dust removal treatments such as absorption towers and washing equipment, the temperature of the flue gas discharged from the chimney is still as high as 80 ~85°C, under normal ambient temperature conditions, the exhaust gas is generally white, misty water vapor mixture, and the sensory effect is poor, especially in autumn and winter

If the above-mentioned hydrochloric acid waste liquid regeneration unit is close to the residential area, the "white smoke billowing" exhaust gas discharged from the chimney will often become the object of complaints from residents in the surrounding residential areas of the hydrochloric acid waste liquid regeneration unit, which will bring great harm to steel or chemical companies. pressure

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