Acid regeneration operation system and method

Abstract

The invention provides an acid regeneration operation system and method. The acid regeneration operation system comprises a treated acid collecting device, a treated acid concentrating device, a roasting device, a furnace gas pre-washing device and a hydrogen chloride absorbing device; the treated acid collecting device is connected with the treated acid concentrating device, the treated acid concentrating device is connected with the roasting device, the roasting device is connected with the furnace gas pre-washing device, the furnace gas pre-washing device is connected with the treated acid concentrating device, and the treated acid concentrating device is connected with the hydrogen chloride absorbing device. According to the invention, excessive iron oxide powder can be prevented from entering the treated acid concentration device, the carrying amount of the iron oxide powder in the concentrated treated acid is reduced, the large concentration ratio of the treated acid caused by too high furnace gas temperature can be avoided, and the problems that an absorption tower is easy to damage and the acid regeneration efficiency is relatively low can be solved; in addition, the energy utilization rate is high, and the content of hydrogen chloride in discharged gas is low.

Description

Technical Field

[0001] This invention relates to the field of acid regeneration, and more particularly to an acid regeneration operating system and method. Background Technology

[0002] Before continuous pickling and rolling, steel strip needs to undergo pickling and rinsing sequentially. The pickling solution obtained after pickling is pretreated to obtain treatment acid, which contains ferrous chloride. This treatment acid is then concentrated and roasted in an iron oxide powder roasting furnace to obtain iron oxide powder and furnace gas. The furnace gas contains hydrogen chloride gas and may contain some iron oxide powder. Currently, the furnace gas and treatment acid are typically subjected to heat and mass exchange in a Venturi pre-concentrator to concentrate the treatment acid. The furnace gas after heat and mass exchange is then sent to an absorption tower. In the absorption tower, the furnace gas and the rinsing water obtained from the aforementioned rinsing process generate regenerated acid, which can be used for pickling the steel strip.

[0003] During the acid regeneration process described above, the furnace gas undergoes heat and mass exchange with the treated acid, causing some iron oxide powder to enter the concentrated treated acid along with the furnace gas. This increases the probability of blockage in the roasting furnace supply pipe and the roasting furnace spray assembly due to iron oxide powder. Furthermore, by only installing a Venturi pre-concentrator to allow heat and mass exchange between the furnace gas and the treated acid, the high-temperature furnace gas undergoes a large concentration ratio, which easily leads to a high probability of crystallization blockage in the roasting furnace supply pipe and nozzles. In addition, the furnace gas discharged from the Venturi pre-concentrator directly enters the hydrogen chloride absorption tower. At this point, the furnace gas temperature is still relatively high, which not only affects the absorption efficiency of hydrogen chloride but also easily damages the absorption tower.

[0004] Therefore, it is necessary to provide an acid regeneration operation system and method to solve the technical problems of easily carrying iron oxide powder in concentrated acid, large acid concentration ratio, easy damage to the absorption tower by furnace gas, and low acid regeneration efficiency. Summary of the Invention

[0005] The main objective of this invention is to provide an acid regeneration system and method, which aims to solve the technical problems of easily carrying iron oxide powder in concentrated acid, large acid concentration ratio, easy damage to the absorption tower by furnace gas, and low acid regeneration efficiency.

[0006] To achieve the above objectives, the present invention provides an acid regeneration operation system, which includes an acid collection device, an acid concentration device, a roasting device, a furnace gas pre-washing device, and a hydrogen chloride absorption device. The treated acid collection device is connected to the treated acid concentration device and supplies treated acid to the treated acid concentration device. The treated acid contains ferrous chloride. The treated acid concentration device is connected to the roasting device and supplies concentrated acid to the roasting device. After roasting, roasting furnace gas and iron oxide powder are obtained. Some iron oxide powder is mixed in the roasting furnace gas. The roasting device is connected to the furnace gas pre-washing device and supplies roasting furnace gas to the furnace gas pre-washing device. The roasting furnace gas comes into contact with the first rinsing water in the furnace gas pre-washing device to obtain pre-washing liquid and pre-washed furnace gas. The furnace gas pre-washing device is connected to the treated acid concentration device and supplies pre-washed furnace gas to the treated acid concentration device. The pre-washed furnace gas comes into contact with the treated acid in the treated acid concentration device to obtain concentrated acid and furnace gas to be absorbed. The treated acid concentration device is connected to the hydrogen chloride absorption device and supplies furnace gas to be absorbed to the hydrogen chloride absorption device. The furnace gas to be absorbed comes into contact with the absorption liquid containing the pre-washing liquid to obtain regenerated acid and furnace gas to be washed.

[0007] Furthermore, the absorbent includes a pre-wash solution and a second rinse water; the acid regeneration operating system also includes a rinse water collection device, the furnace gas pre-wash device is connected to the rinse water collection device, and the pre-wash solution is supplied to the rinse water collection device; the rinse water collection device is connected to the hydrogen chloride absorption device, and the absorbent is supplied to the hydrogen chloride absorption device; the rinse water collection device is also connected to a rinse water supply device to receive the second rinse water supplied by the rinse water supply device; The first rinsing water entering the furnace gas pre-washing device includes a pre-washing liquid and a second rinsing water. The rinsing water collection device supplies the pre-washing liquid and the second rinsing water to the furnace gas pre-washing device. The second rinsing water originates from the rinsing water supply device. Alternatively, the first rinsing water entering the furnace gas pre-washing device has the same source as the second rinsing water, and both the first and second rinsing water originate from the rinsing water supply device.

[0008] Furthermore, the furnace gas pre-washing device includes a first Venturi pre-concentrator, the acid treatment concentration device includes a second Venturi pre-concentrator, and the hydrogen chloride absorption device includes an absorption tower.

[0009] Furthermore, the roasting apparatus includes an iron oxide powder roasting furnace; the iron oxide powder roasting furnace is connected to the acid concentration device via a liquid supply pipeline; the top of the iron oxide powder roasting furnace is provided with a spraying assembly for downward spraying concentrated acid; the iron oxide powder roasting furnace is also provided with a first heating assembly and a second heating assembly for supplying heat to the furnace cavity, the first heating assembly being positioned above the middle of the furnace cavity, and the second heating assembly being positioned below the middle of the furnace cavity; the first heating assembly horizontally sprays combustion gas, and the second heating assembly obliquely sprays combustion gas downward.

[0010] Furthermore, the iron oxide powder roasting furnace has a roasting furnace gas outlet at the top and a residual furnace gas outlet at the bottom side position; the roasting furnace gas is discharged outward from the roasting furnace gas outlet and enters the furnace gas pre-washing device; the residual furnace gas at the bottom of the iron oxide powder roasting furnace is discharged from the residual furnace gas outlet.

[0011] Furthermore, the acid regeneration operation system also includes a suction device; the suction device draws the roasting furnace gas into the furnace gas pre-washing device.

[0012] Furthermore, the acid regeneration operation system also includes a dust collector, which is installed on the pipeline connecting the roasting device and the furnace gas pre-washing device; the dust collector partially separates the iron oxide powder mixed in the roasting furnace gas and returns it to the roasting device.

[0013] Furthermore, the acid regeneration operation system also includes a filtration device, which is installed on the pipeline connecting the treated acid collection device and the treated acid concentration device to filter the treated acid; The acid regeneration operation system also includes a furnace gas scrubbing device; the hydrogen chloride absorption device is connected to the furnace gas scrubbing device and supplies furnace gas to be scrubbed to the furnace gas scrubbing device; the furnace gas scrubbing device includes a furnace gas scrubbing tower.

[0014] The present invention also provides an acid regeneration method, which uses an acid regeneration operating system as described above to regenerate acid and obtain regenerated acid.

[0015] The present invention also provides an acid regeneration method, comprising: collecting treated acid containing ferrous chloride; concentrating the treated acid to obtain concentrated acid; and calcining the concentrated acid to obtain iron oxide powder and calcination furnace gas, wherein the calcination furnace gas contains some iron oxide powder. The roasting furnace gas is contacted with the first rinsing water to obtain a pre-washing liquid and pre-washing furnace gas; the temperature of the pre-washing furnace gas is lower than that of the roasting furnace gas; the pre-washing furnace gas is used to treat the concentration of acid to obtain concentrated acid and furnace gas to be absorbed; the temperature of the furnace gas to be absorbed is lower than that of the pre-washing furnace gas; the furnace gas to be absorbed is contacted with the absorbent liquid to obtain regenerated acid and furnace gas to be washed; the absorbent liquid includes the pre-washing liquid and the second rinsing water.

[0016] Compared with the prior art, the present invention has at least the following advantages: This invention provides an efficient, energy-saving, and environmentally friendly operating system and method for acid regeneration. It avoids excessive iron oxide powder entering the acid concentration unit, reducing the amount of iron oxide powder carried over in the concentrated acid. It also prevents a high concentration ratio of the treated acid due to excessively high furnace temperature, and solves the problems of easy damage to the absorption tower and low acid regeneration efficiency. Furthermore, this invention has high energy utilization and low hydrogen chloride content in the exhaust gas, meeting environmental protection requirements.

[0017] This invention incorporates a furnace gas pre-washing device between the roasting apparatus and the acid concentration apparatus. The roasting furnace gas first contacts the first rinse water, concentrating the rinse water which has a high heat capacity and absorption capacity. The first rinse water absorbs a portion of the hydrogen chloride and heat from the roasting furnace gas, as well as most of the impurities of iron oxide powder, yielding a pre-washing liquid. This first rinse water is acidic, and its acidity increases further after absorbing hydrogen chloride from the roasting furnace gas. The pre-washing liquid then enters a hydrogen chloride absorption device where it contacts the cooled furnace gas to obtain regenerated acid. In a preferred embodiment, when the pre-washing liquid and the second rinse water are used together as the absorbent, the temperature, acidity, and volume of the absorbent can be controlled, and the rinse water can be fully reused. Furthermore, after the pre-washing liquid and the second rinse water are mixed, the heat from the pre-washing liquid remains in the absorbent and is subsequently transferred to the regenerated acid, without causing significant energy loss.

[0018] The pre-washed furnace gas, obtained after contacting the roasting furnace gas with the first rinsing water, enters the acid concentration unit. This is equivalent to the furnace gas undergoing preliminary cooling and cleaning before contacting the acid to be treated in the concentration unit. Therefore, the concentration ratio of the acid to be treated can be reduced, avoiding blockage of pipelines and nozzles caused by an excessively high concentration ratio. It can also reduce the amount of iron oxide powder in the concentrated acid, avoiding blockage of pipelines and nozzles due to the incorporation of iron oxide powder. The furnace gas to be absorbed, obtained after the pre-washed furnace gas contacts the acid to be treated, has essentially undergone two cooling processes. When it enters the hydrogen chloride absorption unit, it will not be damaged by excessive temperature. Moreover, the lower furnace gas temperature can better ensure the absorption of hydrogen chloride, thereby improving the efficiency of acid regeneration and helping to solve the environmental problems caused by the incorporation of hydrogen chloride in the exhaust gas. Furthermore, this invention utilizes rinsing water for two-stage absorption of hydrogen chloride in the furnace gas. During pre-washing, the rinsing water absorbs some of the hydrogen chloride in the furnace gas and is concentrated, increasing the acid concentration in the rinsing water. Subsequently, it comes into contact with the cooled furnace gas for secondary absorption of hydrogen chloride, making it easier to increase the acid concentration and improving the acid production efficiency of the regenerated acid. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of an acid regeneration system according to one embodiment of the present invention; Figure 2 This is a schematic diagram of an acid regeneration system according to another embodiment of the present invention.

[0021] Reference numerals in the attached drawings: 1. Acid collection device; 2. Acid concentration device; 3. Roasting device; 4. Spraying assembly; 5. First heating assembly; 6. Second heating assembly; 7. Furnace gas collection tank; 8. Screw conveyor; 9. Furnace gas pre-washing device; 10. Hydrogen chloride absorption device; 11. Rinsing section; 12. Rinsing water collection device; 13. Suction device; 14. Dust collector; 15. Filter device; 16. First furnace gas scrubbing tower; 17. Second furnace gas scrubbing tower; 18. Regenerated acid tank.

[0022] The realization of the objective, functional characteristics and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0023] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] Furthermore, the technical solutions of the various embodiments of the present invention can be combined with each other, but only if they are based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0025] When numerical ranges are given in the embodiments, it should be understood that, unless otherwise stated in the present invention, both endpoints of each numerical range and any value between the two endpoints may be selected. Unless otherwise defined, all technical and scientific terms used in this invention, as well as the prior art known to those skilled in the art and the description of this invention, may be implemented using any prior art methods, devices, and materials similar to or equivalent to those described, used, or made of materials in the embodiments of this invention.

[0026] In existing technology, the acid is first filtered and then pumped to the top of a Venturi pre-concentrator. There, it is circulated by a Venturi circulation pump, exchanging heat with the furnace gas from the roasting furnace and becoming concentrated. The concentrated and heated acid is then pumped under pressure to a spray gun at the top of the roasting furnace, where it is sprayed into the furnace. Inside the furnace, the concentrated acid reacts with air and water to produce iron oxide powder and furnace gas. The spray gun has nozzles that extend into the furnace cavity. When the pressure rises, the spray gun can be withdrawn for cleaning the nozzles to remove blockages. The concentrated acid is sprayed into a mist from the upper part of the furnace. Three main gas burners are evenly arranged in the middle of the furnace to heat the furnace cavity.

[0027] The furnace gas generated during roasting spirals upwards into the top of the roasting furnace due to the combined effects of the furnace gas fan (located between the absorption tower and the scrubbing tower) and the tangential entry of combustion gases into the furnace waist. The furnace gas exits through the top side opening of the roasting furnace and first passes through a double cyclone dust collector, where centrifugal force and gravity separate a portion of the entrained iron oxide powder. The separated iron oxide powder is then returned to the roasting furnace via a rotary valve at the bottom of the double cyclone. Next, the furnace gas enters the top of the Venturi pre-concentrator to concentrate the acid being processed, while simultaneously cooling the gas. After exiting the Venturi pre-concentrator, the furnace gas enters the absorption tower, where it combines with rinsing water to generate regenerated acid, which is then sent to the regenerated acid tank. Afterward, the furnace gas enters a scrubbing device for two-stage washing, using demineralized water. The washed furnace gas is then discharged into the atmosphere through a chimney.

[0028] In existing technologies, the placement of the gas burner at the furnace waist increases the load on the blower, leading to increased power consumption and a heavier blower load. Furthermore, the ingestion of large amounts of newly generated fine iron oxide powder into subsequent processes causes numerous problems. Current technology uses a single venturi to exchange heat and mass with the furnace gas and the treatment acid (pH 3.5-4.4, no free acid). Some iron oxide powder enters the concentrated treatment acid, increasing the probability of iron oxide powder clogging the supply pipe and nozzles of the roasting furnace. Additionally, with only one venturi, the high-temperature furnace gas undergoes a high concentration ratio during heat and mass exchange with the treatment acid, resulting in a high probability of crystallization clogging of the supply pipe and nozzles of the roasting furnace. For example, before concentration, the treatment acid contains approximately 280-310 g / L of ferrous chloride. If the concentration ratio is high, crystallization clogging will be more severe. If the nozzle becomes clogged, the spray gun must be removed for cleaning and then reinserted into the furnace. Each cleaning causes fluctuations in the quality of the iron oxide powder and wastes energy during acid regeneration. Furthermore, existing technologies use only one venturi, and the temperature of the furnace gas exiting the venturi often exceeds the temperature tolerance of the PP plastic material, causing damage to the absorption tower and its packing material. This, in turn, affects the absorption of hydrogen chloride in the furnace gas, resulting in non-compliance with environmental protection standards.

[0029] See Figure 1-2 To understand this, the present invention provides an acid regeneration operating system, which includes an acid collection device, an acid concentration device, a roasting device, a furnace gas pre-washing device, and a hydrogen chloride absorption device.

[0030] In this invention, the treated acid collection device and the treated acid concentration device are connected, and the treated acid collection device supplies treated acid to the treated acid concentration device; the treated acid is concentrated and heated in the treated acid concentration device to obtain concentrated acid. The treated acid concentration device includes a second Venturi pre-concentrator; the treated acid collection device includes a treated acid storage tank, and the treated acid contains ferrous chloride; in this invention, the source of the treated acid includes: desilication treatment of the pickling solution after steel strip pickling to obtain treated acid; the steel strip pickling uses hydrochloric acid solution, and the source of the hydrochloric acid solution may include the regenerated acid in this invention.

[0031] In this invention, the acid concentration device and the roasting device are connected. The acid concentration device supplies concentrated acid to the roasting device. The concentrated acid is roasted in the roasting device to obtain roasting furnace gas and iron oxide powder. The roasting furnace gas contains some iron oxide powder. The degree of reaction in the iron oxide powder is not limited. It may contain unreacted reactants and is not entirely iron oxide.

[0032] In a preferred embodiment, the roasting apparatus includes an iron oxide powder roasting furnace; the iron oxide powder roasting furnace is connected to the treatment acid concentration device via a liquid supply pipeline to receive concentrated acid; the top of the iron oxide powder roasting furnace is provided with a spraying assembly for downward spraying of concentrated acid, the spraying assembly receives concentrated acid from the liquid supply pipeline and sprays concentrated acid downward from the top of the furnace cavity to atomize it; the spraying assembly includes a spray gun, the lower end of which is provided with a nozzle; the iron oxide powder roasting furnace is also provided with a first heating assembly and a second heating assembly for supplying heat to the furnace cavity, the first heating assembly being positioned above the middle of the furnace cavity, and the second heating assembly being positioned below the middle of the furnace cavity; the first heating assembly horizontally sprays combustion gas, and the second heating assembly obliquely sprays combustion gas downward, the source of the combustion gas including coal gas and combustion air, and the combustion air having a surplus after being supplied for combustion.

[0033] Furthermore, the iron oxide powder roasting furnace has a roasting furnace gas outlet on the top side and a residual furnace gas outlet on the bottom side; the roasting furnace gas is discharged outward from the roasting furnace gas outlet and enters the furnace gas pre-washing device; the residual furnace gas at the bottom of the iron oxide powder roasting furnace is discharged from the residual furnace gas outlet, which is connected to a furnace gas collection tank. The furnace bottom of the iron oxide powder roasting furnace is connected to a screw conveyor for receiving the iron oxide powder obtained in the iron oxide powder roasting furnace.

[0034] Based on the arrangement of the first heating component and the second heating component, a first reaction zone is formed between the first heating component and the top of the furnace cavity; a second reaction zone is formed between the second heating component and the bottom of the furnace cavity, and an intermediate reaction zone is formed between the first reaction zone and the second reaction zone; the first reaction zone has an upward airflow during the roasting process, and the second reaction zone has a downward airflow during the roasting process. Specifically, both the first heating component and the second heating component inject combustion gas into the furnace cavity in a circulating manner; the upward airflow in the first reaction zone is spiral upward, and the downward airflow in the second reaction zone is spiral downward; the spiral directions of the airflow in the first reaction zone and the second reaction zone are opposite. In the first reaction zone, the upward airflow is clockwise spiral upward; in the second reaction zone, the downward airflow is counterclockwise spiral downward. The upward trend of the upward airflow is generated by the suction action of the suction device. The downward trend of the downward airflow is generated by the downward oblique blowing action of the second heating component; the blowing direction of the second heating component forms an angle of 3-15° with the horizontal direction, and further forms an angle of 3-8°.

[0035] This invention improves the iron oxide powder calcining furnace by positioning the first heating element higher than the furnace waist, creating an upward airflow between the first heating element and the furnace top. Furthermore, the amount of combustion gas injected by the first heating element is lower than that injected only at the initial furnace waist in existing technologies, reducing the load on the suction device and further decreasing the amount of iron oxide powder entrained in the furnace gas. As an implementation, this invention sets up a row of three gas burners (upper row) on a plane 2-5 meters below the injection element, controlling the furnace top temperature at 430-450°C. Combustion air and gas enter the gas burners, tangentially entering the furnace cavity for combustion. The airflow enters the furnace horizontally and clockwise. These three gas burners provide the heat source for the initial reaction and the complete evaporation of the concentrated acid, forming a large amount of furnace gas and initial fine iron oxide powder grains. Due to the combined effect of the suction of the suction device and the tangential entry of the combustion gas into the furnace waist, the calcining furnace gas spirals upwards into the top of the calcining furnace. The other row of three gas burners (lower row) is located about 2 meters below the furnace waist, spraying combustion gas diagonally downwards, forming a spiral airflow downwards.

[0036] Furthermore, the present invention provides the first heating component and the second heating component to form a first reaction zone, a second reaction zone and an intermediate reaction zone, which can also solve the contradiction between chlorine content, water content and particle size growth. This not only allows the iron oxide powder to react fully and reduces the chlorine content and water content, but also inhibits the grain growth of the iron oxide powder, thereby obtaining a high-quality iron oxide powder product. The first reaction zone has an upward airflow, the second reaction zone has a downward airflow, and the intermediate reaction zone provides ample space and time for reaction. Therefore, after the concentrated acid is injected into the first reaction zone, it undergoes a preliminary reaction, forming a large amount of furnace gas and a large number of initially unreacted fine iron oxide powder grains. Under the inertia generated by the injection force, the initial fine iron oxide powder grains enter the intermediate reaction zone and gradually lose their initial inertia. Due to the relative balance between the buoyancy of the gas and the gravity of the fine iron oxide powder grains in the second reaction zone, and the ample reaction space provided by the intermediate reaction zone, the initial fine iron oxide powder grains can fully react in the intermediate reaction zone, achieving relatively complete removal of chlorine and moisture. Once the iron oxide powder grains in the intermediate reaction zone grow, and the gravity exceeds the buoyancy, they fall into the second reaction zone. Since the second reaction zone is close to the furnace bottom and has a downward airflow, the iron oxide powder grains in the second reaction zone will quickly fall to the furnace bottom, reducing the space and time for grain growth and preventing further grain growth.

[0037] In this invention, the roasting device and the furnace gas pre-washing device are connected. The roasting device, driven by a suction device, supplies roasting furnace gas to the furnace gas pre-washing device. The roasting furnace gas and the first rinsing water undergo heat and mass exchange in the furnace gas pre-washing device to obtain a pre-washing liquid and pre-washed furnace gas. The furnace gas pre-washing device includes a first Venturi pre-concentrator. The first rinsing water is acidic. After heat and mass exchange with the first rinsing water, some of the hydrogen chloride in the roasting furnace gas enters the acidic pre-washing liquid. In the furnace gas pre-washing device, the amount, acidity, and temperature of free acid in the output pre-washing liquid are greater than those in the input first rinsing water. Most of the iron oxide powder mixed in the roasting furnace gas is absorbed and dissolved by the acidic pre-washing liquid, and the first rinsing water cools the roasting furnace gas.

[0038] In this invention, the furnace gas pre-washing device and the treated acid concentration device are connected. The furnace gas pre-washing device supplies pre-washed furnace gas to the treated acid concentration device. The pre-washed furnace gas comes into contact with the treated acid in the treated acid concentration device for heat and mass exchange, resulting in concentrated acid and furnace gas to be absorbed. The concentrated acid here is the same concentrated acid that was previously supplied to the roasting device. Since the temperature of the pre-washed furnace gas is lower than that of the roasting furnace gas, excessively high furnace gas temperature can prevent excessive concentration ratio and blockage of pipelines and nozzles. Since most of the iron oxide powder in the pre-washed furnace gas has been removed, the problem of blockage caused by iron oxide powder can be reduced.

[0039] In this invention, the acid concentration device and the hydrogen chloride absorption device are connected. The acid concentration device supplies the furnace gas to be absorbed to the hydrogen chloride absorption device. The furnace gas comes into contact with an absorbent containing a pre-washing solution to obtain regenerated acid and furnace gas to be washed. The hydrogen chloride absorption device includes an absorption tower, and the packing and tower body of the absorption tower are made of PP plastic. Because the furnace gas to be absorbed undergoes two stages of cooling—the pre-washing device and the acid pre-concentration device—damage to the absorption tower can be avoided. Furthermore, the lower temperature of the furnace gas is also beneficial for hydrogen chloride absorption. In addition, since some hydrogen chloride has already been absorbed in the pre-washing solution, it also facilitates a rapid increase in the concentration of the regenerated acid.

[0040] Preferably, the absorbent in this invention comprises a pre-washing solution and a second rinsing water; specifically, the absorbent may include a mixture of the pre-washing solution and the second rinsing water; by mixing the pre-washing solution and the second rinsing water, the temperature, acidity, and volume of the absorbent can be controlled.

[0041] Correspondingly, the acid regeneration operation system also includes a rinsing water collection device; the rinsing water collection device includes a rinsing water tank. The furnace gas pre-washing device is connected to the rinsing water collection device, and the furnace gas pre-washing device supplies pre-washing liquid to the rinsing water collection device; the rinsing water collection device is connected to the hydrogen chloride absorption device, and the rinsing water collection device supplies absorbent liquid to the hydrogen chloride absorption device; the rinsing water collection device is also connected to a rinsing water supply device to receive second rinsing water provided by the rinsing water supply device, and the rinsing water supply device includes a strip rinsing section.

[0042] See Figure 1 As shown, in one embodiment of the present invention, the first rinsing water entering the furnace gas pre-washing device comprises a pre-washing liquid and a second rinsing water. The second rinsing water originates from the rinsing water supply device, and the rinsing water collection device supplies the pre-washing liquid and the second rinsing water to the furnace gas pre-washing device. Specifically, the rinsing water collection device and the furnace gas pre-washing device have bidirectional conveying channels. The rinsing water collection device supplies the aforementioned absorbent containing the pre-washing liquid and the second rinsing water to the furnace gas pre-washing device, which is equivalent to a portion of the absorbent entering the hydrogen chloride absorption device and another portion entering the furnace gas pre-washing device as the first rinsing water; the furnace gas pre-washing device supplies the pre-washing liquid to the rinsing water collection device.

[0043] In this scenario, during the initial operation phase, before the pre-washing liquid has formed, the rinsing water collection device contains only the second rinsing water, and the first rinsing water entering the furnace gas pre-washing device is the second rinsing water. Once the pre-washing liquid is formed, it is transported to the rinsing water collection device, where the pre-washing liquid and the second rinsing liquid mix to form the absorbent. Subsequently, the first rinsing water entering the furnace gas pre-washing device contains both the pre-washing liquid and the second rinsing water. In this embodiment, because some of the pre-washing liquid re-enters the furnace gas pre-washing device, the upper limit of hydrogen chloride concentration in the absorbent can be increased, thereby allowing the absorbent to quickly reach the target concentration in the subsequent hydrogen chloride absorption device.

[0044] See Figure 2 As shown, in another embodiment of the present invention, the first rinsing water entering the furnace gas pre-washing device has the same source as the second rinsing water; both the first and second rinsing water can originate from the rinsing water supply device. In this case, the first and second rinsing water can have the same source, both originating from the strip washing section. Further, the rinsing water supply device can be connected to the furnace gas pre-washing device, and the rinsing water supply device provides the first rinsing water to the furnace gas pre-washing device.

[0045] In this invention, the acid regeneration system further includes a regeneration acid tank, the hydrogen chloride absorption device is connected to the regeneration acid tank, the hydrogen chloride absorption device supplies regeneration acid to the regeneration acid tank, and then the regeneration acid in the regeneration acid tank is used in the steel strip pickling section.

[0046] In this invention, the acid regeneration operation system further includes a suction device; the suction device draws the roasting furnace gas into the furnace gas pre-washing device. Specifically, the suction device includes a furnace gas fan; the suction device is located on the pipeline after the hydrogen chloride absorption device, and is used to drive the roasting furnace gas to flow sequentially along the pre-washing device, the treated acid pre-concentration device, and the hydrogen chloride absorption device.

[0047] In this invention, the acid regeneration operation system further includes a furnace gas scrubbing device. The hydrogen chloride absorption device is connected to the furnace gas scrubbing device, and the hydrogen chloride absorption device supplies furnace gas to be scrubbed to the furnace gas scrubbing device. Correspondingly, the suction device is located on the pipeline connecting the hydrogen chloride absorption device and the furnace gas scrubbing device. The furnace gas scrubbing device includes a furnace gas scrubbing tower; the furnace gas scrubbing tower consists of a first furnace gas scrubbing tower and a second furnace gas scrubbing tower connected in sequence.

[0048] Furthermore, the first furnace gas scrubbing tower uses the rinse water from the steel strip washing process to scrub the furnace gas, and the scrub water is then returned to the rinse water tank. The ability of the rinse water to absorb trace amounts of hydrogen chloride in the furnace gas is also necessary to meet environmental protection standards. The second furnace gas scrubbing tower uses demineralized water to scrub the furnace gas, and the scrub water is then returned to the rinse water tank. Since demineralized water does not contain any ions, it has a large absorption capacity for any substances in the furnace gas other than water, making it the final process before the furnace gas is discharged. Based on this, as a preferred embodiment, the absorbent delivered to the hydrogen chloride absorption device may also include the liquid from the first and second furnace gas scrubbing towers after scrubbing with rinse water and demineralized water.

[0049] In this invention, the acid regeneration operation system further includes a dust collector, which is installed on the pipeline connecting the roasting device and the furnace gas pre-washing device. The dust collector partially separates the iron oxide powder entrained in the roasting furnace gas and returns it to the roasting device. The dust collector includes a dual cyclone dust collector. After being separated by the dust collector, the roasting furnace gas still carries some iron oxide powder, thus requiring the pre-washing device to be installed.

[0050] In this invention, the acid regeneration system further includes a filtration device, which is installed on the pipeline connecting the treated acid collection device and the treated acid concentration device to filter the treated acid. The filtration device includes a filter, and the treated acid collection device includes a treated acid tank. The filtration device is capable of removing impurities from the treated acid, removing particulate matter.

[0051] The present invention also provides an acid regeneration method, which uses the acid regeneration operating system described above to regenerate the treated acid and obtain regenerated acid.

[0052] The present invention provides an acid regeneration method comprising: collecting treated acid containing ferrous chloride; concentrating the treated acid to obtain concentrated acid; and calcining the concentrated acid to obtain iron oxide powder and calcination furnace gas, wherein the calcination furnace gas contains some iron oxide powder.

[0053] The roasting furnace gas is contacted with the first rinsing water to obtain a pre-washing liquid and pre-washing furnace gas. The pre-washing liquid absorbs part of the heat, part of the hydrogen chloride, and most of the iron oxide powder in the roasting furnace gas, and the temperature of the pre-washing furnace gas is lower than that of the roasting furnace gas. The pre-washing furnace gas is used to treat the concentration and heating of acid to obtain concentrated acid and furnace gas to be absorbed. The temperature of the furnace gas to be absorbed is lower than that of the pre-washing furnace gas. The furnace gas to be absorbed is contacted with the absorbent liquid, and the absorbent liquid absorbs the hydrogen chloride in the furnace gas to be absorbed to obtain regenerated acid and furnace gas to be washed. The absorbent liquid includes the pre-washing liquid and the second rinsing water.

[0054] As one embodiment of the present invention, the acid regeneration system described above is used for the regeneration of the treated acid. The acid regeneration method specifically includes: collecting the treated acid into the treated acid collection device; concentrating the treated acid in the treated acid concentrator to obtain concentrated acid; roasting the concentrated acid in the roasting device, during which concentrated acid is sprayed from top to bottom to obtain iron oxide powder and roasting furnace gas, the roasting furnace gas containing some iron oxide powder; contacting the roasting furnace gas and first rinsing water in the pre-washing device to obtain pre-washing liquid and pre-washing furnace gas; most of the iron oxide powder contained in the roasting furnace gas enters the pre-washing liquid, and the temperature of the pre-washing furnace gas is lower than that of the roasting furnace gas; concentrating the treated acid in the treated acid concentration device to obtain concentrated acid and furnace gas to be absorbed; the temperature of the furnace gas to be absorbed is lower than that of the pre-washing furnace gas; contacting the furnace gas to be absorbed with the absorption liquid in the hydrogen chloride absorption device to obtain regenerated acid and furnace gas to be washed.

[0055] In this invention, the roasting gas generated by the iron oxide powder roasting furnace carries iron oxide powder. Under the gravity of the double cyclone dust collector, a portion of the iron oxide powder is removed. In the first Venturi (pre-washing device), it undergoes heat and mass exchange with acidic rinsing water, absorbing a portion of the hydrogen chloride in the furnace gas and washing the furnace gas, allowing the majority of the entrained iron oxide powder to enter the acidic rinsing water. Next, the pre-washed furnace gas enters the second Venturi (treatment acid pre-concentration device) and undergoes heat and mass exchange with treatment acid (pH 3.5-4.4, no free acid), allowing the clarified concentrated acid to enter the roasting furnace, reducing crystallization blockage of the liquid supply pipe and nozzles (the concentration ratio is reduced in the second Venturi) and iron oxide powder blockage. It is important to understand that iron oxide powder entering the treatment acid is difficult to dissolve due to the lack of free acid. Even if the treatment acid absorbs a small amount of hydrogen chloride from the furnace gas, the free acid level remains low. Furthermore, within a short timeframe—specifically, during storage in the collection tank at the bottom of the venturi and transport via the supply pipe—the iron oxide powder cannot be dissolved in the treatment acid, easily leading to blockage. In this invention, the furnace gas exiting from the second venturi re-enters the absorption tower. Since the furnace gas is already clean, it will not form oxide scale on the absorption tower packing, thus affecting the absorption tower efficiency. Additionally, the furnace gas temperature has been significantly reduced, resulting in high efficiency of the rinsing water in absorbing the hydrogen chloride mist from the furnace gas. This also protects the absorption tower packing and the absorption tower body (as both are made of PP plastic). The furnace gas to be washed exiting the absorption tower meets emission standards after washing.

[0056] The following is a further explanation of the two-stage Venturi and two-stage absorption in this invention: This invention first concentrates the rinsing water, which has a high heat capacity and absorption capacity, in the first Venturi (pre-washing device). The rinsing water (containing 5-10 g / L of free hydrochloric acid, the remainder being water, which has a high specific heat capacity) absorbs a portion of the hydrogen chloride and most of the iron oxide powder mixed in with the furnace gas. The rinsing water is acidic and has a certain initial temperature. After absorbing the hydrogen chloride from the furnace gas, the acidity increases, and the water temperature also increases. The absorbed iron oxide powder will dissolve in the rinsing water after pre-washing (pre-washing liquid). However, it should be noted that because water in the rinsing water has a high specific heat capacity, the temperature rise of the pre-washing liquid after absorbing the heat from the furnace gas will not be particularly high. The pre-washing liquid flows back to the rinsing water tank, and can then enter the absorption tower to absorb the remaining hydrogen chloride in the furnace gas, obtaining hot regenerated acid (containing 170-190 g / L of free hydrochloric acid), which is then fed into the strip pickling process, resulting in high thermal energy utilization. The pre-washed furnace gas is concentrated in a second venturi (acid concentration unit) to treat the waste acid, reducing the concentration ratio of the waste acid. Simultaneously, the furnace gas entering the second venturi is cleaner, reducing the probability of blockage. After exiting the second venturi, the temperature of the furnace gas decreases further, preventing damage to the absorption tower. The PP plastic absorption tower and its packing equipment remain intact. This invention, through two stages of venturi processes, one absorption tower, and two stages of scrubbing towers, achieves complete and environmentally friendly absorption of hydrogen chloride in the furnace gas, consistently meeting standards of ≤30mg / standard cubic meter.

[0057] In this invention, the amount of concentrated acid solution supplied to the iron oxide powder roasting furnace is usually fixed. The concentration ratio of the treated acid is controlled by adjusting the amount of rinsing water sprayed into the top of the first venturi to meet production needs (more rinsing water is sprayed when the furnace gas temperature at the top of the furnace is high, and less is sprayed when it is low). This adds a control method compared to the existing technology, which cannot control this.

[0058] This invention achieves two-stage absorption of hydrogen chloride in the furnace gas, better ensuring the regenerated acid concentration reaches (170-190 g / L containing free hydrochloric acid). Because the first venturi concentrates the high-heat-capacity and high-absorption-capacity rinsing water to absorb hydrogen chloride from the furnace gas, on the one hand, the rinsing water absorbs a large amount of hydrogen chloride from the furnace gas; on the other hand, the rinsing water is concentrated, increasing its concentration, and then flows back to the rinsing water tank for concentration and temperature homogenization. Subsequently, the absorption tower can focus on absorbing hydrogen chloride from the furnace gas. In this way, the regenerated acid concentration is easily achieved, improving the acid production efficiency, unlike existing technologies that only perform absorption once in the absorption tower until the regenerated acid concentration is reached (increasing the rinsing water concentration from 5-10 g / L to 170-190 g / L in the absorption tower is actually a slow process).

[0059] This invention achieves two-stage absorption. First, it rapidly reaches the concentration of regenerated acid. Second, with the same efficiency as primary absorption, the resulting regenerated acid concentration will be greater than 190 g / L, allowing for the use of this higher-concentration regenerated acid in push-pull pickling lines to meet the requirements of difficult-to-pick steel grades (such as silicon steel, which has higher requirements for the free acid concentration in the pickling solution). Third, if the concentration is only 170-190 g / L, the acid production capacity will be increased, meaning the hourly acid production will be higher (this is a highly feasible solution for improving acid regeneration capacity, provided other conditions are met). Furthermore, regarding the absorption of furnace gas in the second-stage Venturi: the concentration of chloride ions in the treated acid is already relatively high (the capacity for absorbing chloride ions is limited), and the concentration is further increased by concentration, while the temperature also rises, thus creating a balance between the absorption and volatilization of hydrogen chloride. Even if hydrogen chloride dissolves, it will volatilize at the higher temperature of the roasting furnace and enter the first-stage Venturi where it is absorbed by the large-capacity rinsing water, and is further absorbed by the rinsing water in the absorption tower.

[0060] The above technical solutions of the present invention are merely preferred embodiments of the present invention and do not limit the patent scope of the present invention. All equivalent structural transformations made under the technical concept of the present invention using the contents of the present invention specification and drawings, or direct / indirect applications in other related technical fields, are included in the patent protection scope of the present invention.

Claims

1. An acid regeneration operation system, characterized in that, The acid regeneration operation system includes an acid collection device, an acid concentration device, a roasting device, a furnace gas pre-washing device, and a hydrogen chloride absorption device. The treated acid collection device is connected to the treated acid concentration device and supplies treated acid to the treated acid concentration device. The treated acid contains ferrous chloride. The treated acid concentration device is connected to the roasting device and supplies concentrated acid to the roasting device. After roasting, roasting furnace gas and iron oxide powder are obtained. Some iron oxide powder is mixed in the roasting furnace gas. The roasting device is connected to the furnace gas pre-washing device and supplies roasting furnace gas to the furnace gas pre-washing device. The roasting furnace gas comes into contact with the first rinsing water in the furnace gas pre-washing device to obtain pre-washing liquid and pre-washed furnace gas. The furnace gas pre-washing device is connected to the treated acid concentration device and supplies pre-washed furnace gas to the treated acid concentration device. The pre-washed furnace gas comes into contact with the treated acid in the treated acid concentration device to obtain concentrated acid and furnace gas to be absorbed. The treated acid concentration device is connected to the hydrogen chloride absorption device and supplies furnace gas to be absorbed to the hydrogen chloride absorption device. The furnace gas to be absorbed comes into contact with the absorption liquid containing the pre-washing liquid to obtain regenerated acid and furnace gas to be washed.

2. The acid regeneration operation system according to claim 1, characterized in that, The absorbent includes a pre-wash solution and a second rinse water; the acid regeneration operating system also includes a rinse water collection device, the furnace gas pre-wash device is connected to the rinse water collection device, and the pre-wash solution is supplied to the rinse water collection device; the rinse water collection device is connected to the hydrogen chloride absorption device, and the absorbent is supplied to the hydrogen chloride absorption device; the rinse water collection device is also connected to a rinse water supply device to receive the second rinse water supplied by the rinse water supply device. The first rinsing water entering the furnace gas pre-washing device includes a pre-washing liquid and a second rinsing water. The rinsing water collection device supplies the pre-washing liquid and the second rinsing water to the furnace gas pre-washing device. The second rinsing water originates from the rinsing water supply device. Alternatively, the first rinsing water entering the furnace gas pre-washing device has the same source as the second rinsing water, and both the first and second rinsing water originate from the rinsing water supply device.

3. The acid regeneration operation system according to claim 1, characterized in that, The furnace gas pre-washing device includes a first Venturi pre-concentrator, the acid treatment concentration device includes a second Venturi pre-concentrator, and the hydrogen chloride absorption device includes an absorption tower.

4. The acid regeneration operation system according to claim 1, characterized in that, The roasting apparatus includes an iron oxide powder roasting furnace; the iron oxide powder roasting furnace is connected to the acid concentration device via a liquid supply pipeline; the top of the iron oxide powder roasting furnace is provided with a spraying assembly for spraying concentrated acid downwards; the iron oxide powder roasting furnace is also provided with a first heating assembly and a second heating assembly for supplying heat to the furnace cavity, the first heating assembly being positioned above the middle of the furnace cavity, and the second heating assembly being positioned below the middle of the furnace cavity; the first heating assembly horizontally sprays combustion gas, and the second heating assembly obliquely sprays combustion gas downwards.

5. The acid regeneration operation system according to claim 4, characterized in that, The iron oxide powder roasting furnace has a roasting furnace gas outlet at the top and a residual furnace gas outlet at the bottom side position; the roasting furnace gas is discharged outward from the roasting furnace gas outlet and enters the furnace gas pre-washing device; the residual furnace gas at the bottom of the iron oxide powder roasting furnace is discharged from the residual furnace gas outlet.

6. The acid regeneration operation system according to claim 1, characterized in that, The acid regeneration operation system also includes a suction device; the suction device draws the roasting furnace gas into the furnace gas pre-washing device.

7. The acid regeneration operation system according to claim 1, characterized in that, The acid regeneration operation system also includes a dust collector, which is installed on the pipeline connecting the roasting device and the furnace gas pre-washing device; the dust collector partially separates the iron oxide powder mixed in the roasting furnace gas and returns it to the roasting device.

8. The acid regeneration operation system according to claim 1, characterized in that, The acid regeneration operation system also includes a filtration device, which is installed on the pipeline connecting the treated acid collection device and the treated acid concentration device to filter the treated acid. The acid regeneration operation system also includes a furnace gas scrubbing device; the hydrogen chloride absorption device is connected to the furnace gas scrubbing device and supplies furnace gas to be scrubbed to the furnace gas scrubbing device; the furnace gas scrubbing device includes a furnace gas scrubbing tower.

9. A method for acid regeneration, characterized in that, The acid regeneration system described in any one of claims 1-8 is used to regenerate the treated acid, thereby obtaining regenerated acid.

10. A method for acid regeneration, characterized in that, include: Collect the treated acid, which contains ferrous chloride; concentrate the treated acid to obtain concentrated acid; The concentrated acid is roasted to obtain iron oxide powder and roasting furnace gas, and the roasting furnace gas contains some iron oxide powder. The roasting furnace gas and the first rinsing water are brought into contact to obtain pre-washing liquid and pre-washing furnace gas; The temperature of the pre-wash furnace gas is lower than that of the roasting furnace gas; the pre-wash furnace gas is used to treat the concentration of the acid to obtain concentrated acid and furnace gas to be absorbed; the temperature of the furnace gas to be absorbed is lower than that of the pre-wash furnace gas; the furnace gas to be absorbed is contacted with the absorbent liquid to obtain regenerated acid and furnace gas to be washed; the absorbent liquid includes the pre-wash liquid and the second rinse water.

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