Treatment system for tail gas generated during acid and water conversion in cold rolling acid-washing acid-regenerating process

Abstract

The invention relates to a treatment system for tail gas generated during acid and water conversion in a cold rolling acid-washing acid-regenerating process, belonging to the technical field of cold rolling acid-washing acid-regenerating devices in metallurgical industry. The technical scheme is as follows: a bypass pipeline is additionally arranged by the side of an acid charge regulating valve (10) of a pre-concentration device and is provided with a regulating valve (11); and the regulating valve is not controlled by an acid operation mode and a water operation mode and can be randomly opened or closed, and the regulating valve is opened when the system carries out the conversion in advance and is closed in a normal acid operation mode or rinsing water operation mode. The treatment system directly converts a new water operation into an acid operation when carrying out acid and water conversion in advance so as to solve an atmosphere pollution problem because the tail gas contains iron ions when acid and water are converted during acid regeneration. During conversion, waste acid returns to a waste acid pot so as to be saved, thus acid pollution is avoided; and in addition, acid-including waste water discharged to water to be treated is reduced due to acid regeneration, and water treatment cost is reduced.

Description

technical field [0001] The invention relates to a treatment system for tail gas produced by conversion of acid and water in a cold-rolled pickling acid regeneration process, and belongs to the technical field of cold-rolled pickling acid regeneration equipment in the metallurgical industry. Background technique [0002] At present, all the waste acid produced by the pickling unit in the metallurgical industry is sent to the acid regeneration process. The acid regeneration device works independently of the pickling unit. Its principle is to regenerate the waste acid from pickling through roasting, dust removal, cooling and absorption, and return it to the pickling unit to obtain iron oxide powder. For the process flow, see the attached figure 1 , The process is divided into four operation modes: 1. Fresh water operation mode: after pressurized, domestic water is controlled by a valve and directly enters the spray gun to completely clean the roaster. 2. Rinsing water operatio...

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Problems solved by technology

[0003] The problem in the background technology is: when the liquid level of the pre-concentrator drops to the set value (the program is automatically set without operation), the acid inlet valve of the pre-concentrator is automatically set at the operating position, and the acid liquid is replenished to the pre-concentrator; Although the system switches to acid operation at this time, the liquid sprayed in the roaster is still water or the mixed liquid of acid and water; since the amount of liquid delivered to the roaster is constant, the amount of spent acid added to the pre-concentrator is also constant

In the initial stage of acid operation, the liquid in the pre-concentrator is a mixed liquid with less acid and more water. The combustion hot gas in the roaster contains HCL and iron ions. The HCL content in the pre-concentrated circulating liquid is low and cannot absorb iron ions in the combustion hot gas. , or iron ions cannot be dissolved in the acid-water mixture. Although the combustion hot gas containing iron ions is partly blocked by the packing of the absorption tower and the washing tower, the iron ions that cannot be completely absorbed are discharged into the atmosphere along with the tail gas through the chimney. Due to the high concentration of iron ions, the exhaust gas is red, which seriously pollutes the environment

As the acid operation of the system continues, the liquid in the pre-concentrator is gradually replaced by water to acid, and the iron ions in the tail gas gradually decrease until they disappear. It takes a certain amount of time. During the time when the liquid is completely replaced with acid, the color of the exhaust gas from the outside is the process of gradually changing from red to white. The red exhaust gas discharged during this process contains a large amount of iron ions, which seriously pollutes the environment and needs to be treated urgently.

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