Method and system for regenerating hydrochloric acid waste liquid

Abstract

The invention relates to a method for regenerating hydrochloric acid waste liquid. According to the method, a spray roasting method is adopted, and the hydrochloric acid waste liquid is preheated through circulating liquid in at least one washing mechanism in the second-stage washing mechanism and washing mechanisms behind the second-stage washing mechanism. The invention further relates to a system for regenerating the hydrochloric acid waste liquid. The system comprises a roasting furnace, a Venturi preconcentrator, an absorption tower and multiple stages of washing mechanisms, all of which are sequentially connected through a smoke pipeline, and a third heat exchange mechanism is arranged on a circulating liquid pipeline of at least one of the second-stage washing mechanism and the washing mechanisms behind the second-stage washing mechanism. Refrigerant inlets of all the third heat exchange mechanisms are connected with a hydrochloric acid waste liquid storage tank, and refrigerant outlets are all connected with the Venturi preconcentrator. The hydrochloric acid waste liquid is preheated through the circulating liquid of the corresponding washing mechanisms, energy saving and consumption reducing are achieved, and the regenerating and recycling efficiency of the hydrochloric acid waste liquid can be improved. Meanwhile, the circulating liquid of the corresponding washing mechanisms is cooled, the heat exchange amount of the low-temperature circulating liquid and smoke is larger, and the washing effect of the washing mechanisms can be improved.

Description

Technical field [0001] The invention relates to a regeneration method and a regeneration system of hydrochloric acid waste liquid. Background technique [0002] The hydrochloric acid pickling waste liquid produced by steel or chemical enterprises is currently generally used 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 for heating and concentration, and then passes through the Venturi. The pre-concentrator circulating pump and the roasting furnace feed pump are pressurized and sprayed into the roasting furnace as mist droplets. After chemical reaction in the roasting furnace, the droplets produce HCl and H 2 O, O 2 , CO 2 , N 2 And a small amount of Fe 2 O 3 The high-temperature flue gas of powder (390~410℃); (2) The above-mentioned high-temperature flue gas enters the Venturi preconcentrator and exchanges heat with the waste hydrochloric aci...

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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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