A hydrochloric acid regeneration flue gas emission system and emission method

Abstract

The present application relates to a kind of hydrochloric acid regeneration flue gas emission system and emission method, belong to waste hydrochloric acid regeneration technical field, solve the existing hydrochloric acid regeneration device process backward, cannot guarantee the hydrogen chloride content in the emission to atmosphere is lower than 20mg / m 3 , dust particulate matter concentration is lower than 10mg / m 3 .The system includes absorption unit, cooling unit, separation unit, exhaust unit and washing unit in turn along the flue gas flow direction;Monitoring device is provided on washing unit, for monitoring the pollutant content of emission flue gas;Absorption unit is used to absorb hydrogen chloride in flue gas, forms regenerated hydrochloric acid;Separation unit is used to separate the dust particles and liquid beads above 1 μm in flue gas.The system not only realizes that the hydrogen chloride content in the emission to atmosphere of cold-rolled steel hydrochloric acid regeneration unit is lower than 20mg / m 3 , dust particulate matter concentration is lower than 10mg / m 3 , and the water vapor content in flue gas is greatly reduced, and emission flue gas temperature is not higher than 60 DEG C.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of waste hydrochloric acid regeneration, and particularly relates to a hydrochloric acid regeneration flue gas emission system and an emission method. BACKGROUND

[0002] In the field of waste hydrochloric acid treatment, the steel industry generally adopts a spray roasting method to recycle and regenerate waste hydrochloric acid. In this method, concentrated waste hydrochloric acid liquid is sprayed into a high-temperature zone of a roasting furnace reactor, and after chemical heat treatment, high-temperature flue gas is cooled and dedusted by a Venturi pre-concentrator. After cooling, the flue gas is purified by absorption and then discharged into the atmosphere through a chimney. The general flue gas absorption and purification process is as follows: the flue gas is first cooled, and then introduced into a primary absorption tower and / or a secondary absorption tower. After absorption, the flue gas enters a gas-liquid separator through a waste gas fan. After gas-liquid separation, the liquid is introduced into a dechlorination tower or directly introduced into a washing tower.

[0003] Although some units are now conducting research on ultra-low emission of hydrochloric acid regeneration flue gas, most of these researches use heat exchangers to cool the absorption tower and washing tower absorption liquid to improve the absorption effect. These processes can to some extent reduce the content of hydrogen chloride in the flue gas, but the content of dust particulate matter often exceeds the standard, and it is impossible to achieve a hydrogen chloride content of not higher than 20 mg / m 3 and a dust particulate matter concentration of not higher than 10 mg / m 3 . SUMMARY

[0004] In view of the above analysis, the embodiments of the present application aim to provide a hydrochloric acid regeneration flue gas emission system and an emission method to solve the technical problem of substandard treatment of hydrogen chloride and dust in the existing flue gas absorption and purification process.

[0005] The hydrochloric acid regeneration flue gas emission system of the present application comprises, in sequence along the flow direction of the flue gas, an absorption unit, a cooling unit, a separation unit, an exhaust unit and a washing unit. A monitoring device is arranged on the washing unit to monitor the pollutant content of the emission flue gas.

[0006] The absorption unit is used to absorb hydrogen chloride in the flue gas to form regenerated hydrochloric acid. The separation unit is used to separate dust particles and liquid beads with a size of more than 1 μm in the flue gas. The washing unit is used to wash and purify the flue gas.

[0007] Further, the washing unit is a washing tower, the bottom of the washing tower is a packing section, the middle part is provided with a water film absorption section, and the top is provided with a mist removal device. The flow direction of the flue gas is from bottom to top.

[0008] Further, the separation unit is a gas-liquid cyclone separator, and the gas-liquid cyclone separator comprises a plurality of gas-liquid cyclone sub-assemblies.

[0009] Further, the hydrochloric acid regeneration system further comprises a collection unit, the collection unit being connected with the absorption unit and the gas-liquid cyclone separator respectively, and the gas-liquid cyclone separator stores the liquid beads generated by the gas-liquid cyclone separator in the collection unit through the first reflux branch.

[0010] Further, the absorption unit comprises a first absorption tower and a second absorption tower, and the collection unit is connected with a spraying layer at the top of the second absorption tower through a second reflux branch, and is connected with a spraying layer at the top of the first absorption tower through a third reflux branch.

[0011] Further, the cooling unit is provided with a circulating cooling water pipeline, and a variable frequency circulating water pump is arranged on the circulating cooling water pipeline, and the variable frequency circulating water pump is used for adjusting and controlling the flue gas cooling amount of the system.

[0012] Further, the cooling unit is a flue gas cooler, the flue gas cooler adopts a modified graphite heat exchanger, and the flue gas flow direction is from top to bottom.

[0013] The hydrochloric acid regeneration flue gas emission method of the application adopts the above-mentioned hydrochloric acid regeneration system, and the hydrochloric acid regeneration method comprises the following steps:

[0014] S1. The flue gas of the calcination furnace is introduced into the first absorption tower, the absorption liquid is used to absorb the hydrogen chloride in the flue gas, the regenerated acid is formed and discharged from the first absorption tower, the treated flue gas is introduced into the second absorption tower, and the second absorption tower is used to absorb the hydrogen chloride and dust particles;

[0015] S2. The flue gas in the step S1 is introduced into the separation unit after being cooled by the cooling unit, and the separation liquid collected by the separation unit is refluxed to the spraying layer at the top of the first absorption tower and the second absorption tower through the first reflux branch and the second reflux branch respectively;

[0016] S3. The flue gas treated by the separation unit is introduced into the washing unit through the exhaust unit, the washing unit adopts a circulating washing mode to wash the flue gas, and the flue gas is discharged into the atmosphere after being purified by the washing unit.

[0017] Further, the packing section of the washing unit adopts pickling rinsing water as the washing water to wash the flue gas, and the spraying flow of the washing water is adjusted according to the monitoring device, and when the detection value exceeds the set value, the pickling rinsing water is supplemented.

[0018] Further, the water film absorption section of the washing unit adopts industrial water or desalted water as the water film absorption water to wash the flue gas, and the spraying flow of the water film absorption water is adjusted according to the monitoring device, and when the detection value exceeds the set value, the industrial water or desalted water is supplemented.

[0019] Compared with the prior art, the application can at least achieve one of the following beneficial effects:

[0020] (1) This invention uses a gas-liquid cyclone separator to separate dust particles and liquid droplets larger than 1μm from the flue gas, greatly reducing the dust particle content in the flue gas; in addition, the gas-liquid cyclone separator is assembled from ceramic cyclones, which has good corrosion resistance and high separation efficiency, and can discharge 5g / m³ of dust particles. 3 With low liquid separation and pressure loss, it conveniently and reliably removes water droplets and iron oxide particles condensed from the flue gas cooler, reducing the purification load on the final stage scrubbing tower.

[0021] (2) The scrubbing tower of the present invention adopts a three-section tower body. The lower part is a packing section. The packing has the advantages of large specific surface area, high porosity and low bulk density, and is particularly suitable for the removal of low-concentration pollutants at the end. The middle part is a water film absorption section with a water film absorption layer. The flue gas in this section is in full contact with the water film, and the mass transfer and heat transfer effect is good. The top is equipped with a demisting device (e.g., a demister). The demister is used to ensure that the flue gas is less entrained by water mist.

[0022] (3) The flue gas cooler of the present invention adopts a self-cleaning plum blossom-shaped modified graphite heat exchanger. The plum blossom-shaped modified graphite tube has a large heat exchange area, good heat transfer effect, and excellent mechanical properties. The online self-cleaning structure design ensures the long-term reliable operation of the cooler.

[0023] In this invention, the above-described technical solutions can be combined with each other to achieve more preferred combinations. Other features and advantages of this invention will be set forth in the following description, and some advantages may become apparent from the description or be learned by practicing the invention. The objects and other advantages of this invention can be realized and obtained from what is particularly pointed out in the description, claims, and drawings. Attached Figure Description

[0024] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts.

[0025] Figure 1 A schematic diagram of a hydrochloric acid regeneration flue gas emission system is provided for this invention.

[0026] Figure label:

[0027] 1- Primary absorption tower; 2- Secondary absorption tower; 3- Flue gas cooler; 4- Gas-liquid cyclone separator; 5- Exhaust gas fan; 6- Scrubber; 7- Chimney; 8- Flue gas online monitoring instrument; 9- Water collection tank. Detailed Implementation

[0028] Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which form part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not intended to limit the scope of the present invention.

[0029] On the one hand, the present invention provides a hydrochloric acid regeneration flue gas emission system, see appendix. Figure 1 The hydrochloric acid regeneration system includes, in sequence along the flue gas flow direction, an absorption unit, a cooling unit, a separation unit, an exhaust unit, and a washing unit. The washing unit is equipped with a flue gas monitoring device to monitor the pollutant content of the flue gas emitted into the atmosphere. The absorption unit is used to absorb hydrogen chloride in the flue gas to form regenerated hydrochloric acid. The separation unit is used to separate dust particles and liquid droplets larger than 1μm in the flue gas.

[0030] During hydrochloric acid regeneration, the flue gas from the calcination furnace is first introduced into the bottom of the absorption unit. The absorbent liquid inside the absorption unit is sprayed down from the top. During the counter-current convection between the flue gas and the absorbent liquid, most of the hydrogen chloride is absorbed by the absorbent liquid. The flue gas treated by the absorption unit is then introduced into the cooling unit. After cooling to the set temperature, the flue gas is introduced into the separation unit. The separation unit separates dust particles and liquid droplets larger than 1μm from the flue gas. The treated flue gas is then introduced into the scrubbing unit through the exhaust unit. The scrubbing unit further reduces the hydrogen chloride content and significantly reduces the water vapor content in the flue gas, while ensuring that the exhaust gas temperature does not exceed 60℃ and the hydrogen chloride content does not exceed 20mg / m³. 3 The concentration of particulate matter is not higher than 10 mg / m³ 3 .

[0031] The washing unit in this invention is a washing tower 6. The bottom of the washing tower 6 is a packing section, the middle is a water film absorption section, and the top is a demister. The airflow direction of the flue gas is from bottom to top.

[0032] Specifically, the scrubbing tower 6 of the present invention adopts a three-section tower body. The lower part is a packing section, which has the advantages of large specific surface area, high porosity and low bulk density, and is particularly suitable for the removal of low-concentration pollutants at the end. The middle part is a water film absorption section with a water film absorption layer. The flue gas in this section has sufficient contact with the water film and good mass and heat transfer effect. The top is equipped with a demister (e.g., a demister) to ensure that the flue gas is less entrained with water mist.

[0033] To significantly reduce the hydrogen chloride and particulate matter content in the flue gas from the calcining furnace, the separation unit in this invention is a gas-liquid cyclone separator 4. The gas-liquid cyclone separator 4 includes multiple gas-liquid cyclone components (e.g., ceramic cyclones), and these components are capable of discharging 5g / m³ of gas-liquid cyclone gas. 3 Separation liquid.

[0034] Specifically, the flue gas from the roasting furnace absorbs most of the hydrogen chloride in the absorption unit. After absorption and cooling, the flue gas enters the gas-liquid cyclone separator 4. The gas-liquid cyclone separator 4 separates dust particles and liquid droplets larger than 1μm from the flue gas. The liquid droplets are collected to form a separation liquid, while the dust particles are directly disposed of. The gas-liquid cyclone separator 4 of this invention is assembled using ceramic cyclones, which have good corrosion resistance and high separation efficiency, and can discharge 5g / m³ of gas. 3 With low liquid separation and pressure loss, it conveniently and reliably removes water droplets and iron oxide particles condensed from the flue gas cooler 3, reducing the purification load of the final stage scrubbing tower 6.

[0035] In order to store the separated liquid separated from the gas-liquid cyclone separator 4, the hydrochloric acid regeneration system of the present invention also includes a collection unit, which is connected to the absorption unit and the gas-liquid cyclone separator 4 respectively. The gas-liquid cyclone separator 4 collects the separated liquid droplets (the liquid droplets are concentrated together to form the separated liquid) in the collection unit through the first return branch.

[0036] Specifically, the flue gas is introduced into the cooling unit through the absorption unit. The flue gas is cooled by the cooling unit, causing the hydrogen chloride and water vapor in the flue gas to condense into liquid droplets. The liquid droplets adhere to the iron oxide particles. The liquid droplets and iron oxide particles enter the gas-liquid cyclone separator 4 together with the flue gas and are separated by the gas-liquid cyclone separator 4. The separated liquid enters the collection unit (e.g., water collection tank 9), and the purified flue gas is introduced into the washing unit.

[0037] In order to fully separate hydrogen chloride from flue gas and achieve ultra-low emissions of hydrogen chloride, the absorption unit of the present invention includes a primary absorption tower 1 and a secondary absorption tower 2. The collection unit is connected to the spray layer at the top of the secondary absorption tower 2 through a second reflux branch; the collection unit is connected to the spray layer at the top of the primary absorption tower 1 through a third reflux branch.

[0038] Specifically, the primary absorption tower 1 and the secondary absorption tower 2 are connected in series before the cooling unit. The flue gas from the roasting furnace at 89-97°C is introduced into the bottom of the primary absorption tower 1. The flue gas flows from the bottom to the top of the primary absorption tower 1. The absorbent liquid in the spray layer at the top of the primary absorption tower 1 is sprayed downwards from the top, and the flue gas and absorbent liquid form convection. During the convection, the absorbent liquid fully absorbs hydrogen chloride and some dust particles in the flue gas to form regenerated acid. The dust particles dissolve in the regenerated acid at the bottom of the primary absorption tower 1. The regenerated acid is discharged through the pipe at the bottom of the primary absorption tower 1 and sent to other processes for treatment or utilization. The flue gas treated by the primary absorption tower 1 enters the bottom of the secondary absorption tower 2. Similarly, the secondary absorption tower 2 is equipped with a spray layer at the top. The absorbent water in the spray layer is sprayed downwards from the top, forming convection with the flue gas flowing upwards from the bottom. The absorbent water absorbs the residual hydrogen chloride and dust particles in the flue gas, and the absorbed absorbent liquid is transported to the water collection tank 9 through the bottom pipe.

[0039] In order to better cool down the flue gas drawn from the secondary absorption tower 2, the cooling unit is equipped with a circulating cooling water pipeline, and a variable frequency circulating water pump is installed on the circulating cooling water pipeline. The variable frequency circulating water pump is used to adjust the flue gas cooling capacity of the control system.

[0040] Specifically, the flue gas treated by the secondary absorption tower 2 is introduced into the cooling unit. The variable frequency circulating water pump automatically adjusts the circulating water flow rate according to the processing capacity of the hydrochloric acid regeneration unit to ensure that the flue gas temperature at the outlet of the cooling unit is controlled at 55-60℃. The cooling unit can perform periodic online self-cleaning according to the operating time of the hydrochloric acid regeneration unit, with a self-cleaning cycle of 240-360 hours.

[0041] The cooling unit used in this invention is a flue gas cooler 3, which employs a modified graphite heat exchanger with the flue gas flowing from top to bottom. The flue gas cooler 3 of this invention uses a self-cleaning, plum-shaped modified graphite heat exchanger. The plum-shaped modified graphite tube has a large heat exchange area, good heat transfer effect, and excellent mechanical properties. The online self-cleaning structure design ensures long-term reliable operation of the cooler.

[0042] On the other hand, the present invention also provides a method for ultra-low emission of hydrochloric acid regeneration flue gas, which employs the above-mentioned ultra-low emission system for hydrochloric acid regeneration flue gas. The method specifically includes the following steps:

[0043] S1. The flue gas from the 89-97℃ roasting furnace is introduced into the bottom of the top of the first-stage absorption tower 1. At the same time, the absorbent liquid from the top spray layer of the first-stage absorption tower 1 is sprayed downwards. As the absorbent liquid and the flue gas form convection, the absorbent liquid can fully absorb the hydrogen chloride in the flue gas to form regenerated acid. The regenerated acid is discharged from the pipe at the bottom of the first-stage absorption tower 1 and collected.

[0044] S2. The flue gas treated by the primary absorption tower 1 enters the bottom of the secondary absorption tower 2. Similarly, the absorbent water in the top spray layer of the secondary absorption tower 2 is sprayed downwards and forms a convection with the flue gas flowing upwards from the bottom. During the convection process, the absorbent water fully absorbs the residual hydrogen chloride and dust particles in the flue gas. After absorbing the hydrogen chloride and dust particles, the absorbent water is discharged from the bottom of the secondary absorption tower 2 and enters the collection tank. The outlet temperature of the flue gas in the secondary absorption tower 2 is 82-85℃.

[0045] S3. The flue gas treated by the secondary absorption tower 2 enters the flue gas cooler 3. The flue gas cooler 3 adjusts its circulating water volume by controlling the variable frequency circulating water pump according to the flue gas treatment volume of the hydrochloric acid regeneration unit. The outlet flue gas temperature of the flue gas cooler 3 is 55-60℃. At the same time, the flue gas cooler 3 can perform online self-cleaning periodically according to the operating time of the hydrochloric acid regeneration unit. The working cycle of the flue gas cooler 3 is 240-360 hours.

[0046] S4. The flue gas cooled by the flue gas cooler 3 enters the gas-liquid cyclone separator 4. The separated liquid produced by the gas-liquid cyclone separator 4 is discharged into the water collection tank 9. The separated liquid contains a high concentration of hydrogen chloride and iron oxide. After the liquid droplets condensed by the flue gas cooler 3 are processed by the gas-liquid cyclone separator 4, particles and liquid droplets larger than 1μm are 100% separated and removed from the flue gas.

[0047] S5. The flue gas treated by the gas-liquid cyclone separator 4 is introduced into the scrubbing tower 6 through the exhaust gas fan 5, and the temperature of the flue gas entering the scrubbing tower 6 is controlled to be 60-65℃.

[0048] S6. In the scrubbing tower 6, acid rinsing water is used as the scrubbing water, and the flue gas is scrubbed using a circulating scrubbing method. The spray flow rate of the circulating scrubbing water is adjusted according to the data of the online detector in the chimney 7. When the detection value exceeds the set value, rinsing water is added.

[0049] S7. Demineralized water is used as a water film to absorb water in the scrubbing tower 6. The flue gas is purified by water film absorption using a circulating absorption method. The water film absorption water spray flow rate is adjusted according to the data measured by the flue gas online monitoring instrument 8 installed on the chimney 7. When the detected value exceeds the set value, industrial water or demineralized water is added.

[0050] S8. After being purified by scrubbing tower 6, the flue gas is discharged into the atmosphere through chimney 7.

[0051] The ultra-low emission system and method for hydrochloric acid regeneration provided by this invention ensure that the hydrogen chloride content emitted into the atmosphere from the hydrochloric acid regeneration unit of cold-rolled steel does not exceed 20 mg / m³. 3 The concentration of particulate matter is not higher than 10 mg / m³ 3 (National standard specifies 30mg / m³) 3 This significantly reduces the water vapor content in the flue gas and ensures that the temperature of the emitted flue gas does not exceed 60°C, truly achieving the requirements for ultra-low emissions.

[0052] Example 1

[0053] The ultra-low emission system for hydrochloric acid regeneration provided by this invention can be used to process flue gas with a capacity of 3.5 m³. 3 The system processes the hydrochloric acid regeneration flue gas using a hydrochloric acid regeneration unit with a capacity of / h. The parameters of the equipment involved in the ultra-low emission system for hydrochloric acid regeneration flue gas are shown below:

[0054] The inlet temperature of the primary absorption tower 1 is 88–96℃, and the flue gas inlet flow rate of the primary absorption tower 1 is 8700–9500 Nm³. 3 / h, the instantaneous spraying volume is 3.5m³. 3 / h of absorbent water; the area of ​​flue gas cooler 3 is 350m² 2 The cooling capacity is 1,300,000 kcal / h; the gas-liquid cyclone separator 4 is equipped with 30 units with a rated flow rate of 300 m³ / h.3 / h ceramic cyclone; flue gas outlet temperature of flue gas cooler 3 is 55-60℃, outlet gas temperature of chimney 7 is 60℃, and hydrogen chloride content is 13.8mg / m³. 3 Dust particulate matter concentration 9.5 mg / m³ 3 It achieves ultra-low emission standards.

[0055] The ultra-low emission system and method for hydrochloric acid regeneration flue gas provided by this invention reduce the hydrogen chloride content emitted into the atmosphere from cold-rolled steel hydrochloric acid regeneration units to only 13.8 mg / m³. 3 The concentration of particulate matter was 9.5 mg / m³. 3 It is far below the national standard of 30 mg / m³. 3 This significantly reduces the water vapor content in the flue gas, ensuring that the temperature of the emitted flue gas does not exceed 60℃, thus truly achieving the requirements for ultra-low emissions.

[0056] Example 2

[0057] The ultra-low emission system for hydrochloric acid regeneration flue gas provided by this invention is used to treat a hydrochloric acid regeneration unit with a processing capacity of 6.0 m3 / h. The device parameters involved in the ultra-low emission system for hydrochloric acid regeneration flue gas are as follows:

[0058] The inlet temperature of the primary absorption tower 1 is 88–96℃. The flue gas inlet flow rate of the primary absorption tower 1 is 14000–16000 Nm³. 3 / h, the instantaneous spraying volume is 6.0m³ / h. 3 Absorbed water per hour. The area of ​​flue gas cooler 3 is 600 m². 2 The cooling capacity is 2,300,000 kcal / h. The gas-liquid cyclone separator 4 is equipped with 32 units each with a rated flow rate of 500 m³ / h. 3 / h ceramic cyclone. The outlet gas temperature of flue gas cooler 3 is 55-60℃, the outlet flue gas temperature of chimney 7 is 60℃, and the hydrogen chloride content is 15.4mg / m³. 3 Dust particulate matter concentration: 8.9 mg / m³ 3 It achieves ultra-low emission standards.

[0059] The ultra-low emission system and method for hydrochloric acid regeneration flue gas provided by this invention reduce the hydrogen chloride content emitted into the atmosphere from cold-rolled steel hydrochloric acid regeneration units to only 15.4 mg / m³. 3 The concentration of particulate matter was 8.9 mg / m³. 3 It is far below the national standard of 30 mg / m³. 3 This significantly reduces the water vapor content in the flue gas, ensuring that the temperature of the emitted flue gas does not exceed 60℃, thus truly achieving the requirements for ultra-low emissions.

[0060] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A hydrochloric acid regeneration flue gas emission system characterized by, The application relates to a flue gas emission treatment system for a cold-rolled steel hydrochloric acid regenerator unit; the hydrochloric acid regeneration flue gas emission system comprises, in sequence along the flue gas flow direction, an absorption unit, a cooling unit, a separation unit, an exhaust unit and a washing unit; a monitoring device is arranged on the washing unit and used for monitoring the pollutant content of the emission flue gas; The absorption unit is used for absorbing hydrogen chloride in the flue gas to form regenerated hydrochloric acid; the absorption unit comprises a primary absorption tower and a secondary absorption tower; the outlet temperature of the secondary absorption tower is 82-85 DEG C; The flue gas treated by the secondary absorption tower is introduced into the cooling unit; the cooling unit is provided with a circulating cooling water pipeline; a variable frequency circulating water pump is arranged on the circulating cooling water pipeline; the variable frequency circulating water pump automatically adjusts the circulating water flow according to the treatment capacity of the hydrochloric acid regenerator unit; the flue gas temperature at the outlet of the cooling unit is controlled to be 55-60 DEG C; the cooling unit can be periodically and on-line self-cleaned according to the operation time of the hydrochloric acid regenerator unit; the period of the periodic and on-line self-cleaning is 240-360 hours; The cooling unit is a flue gas cooler, the cooling area of the flue gas cooler is 600m 2 , and the cooling capacity is 2300000Kcal / h; the flue gas cooled by the cooling unit enters a separation unit, the separation unit is used for separating dust particles and liquid beads with a size of 1μm or above in the flue gas; the dust particles are iron oxide particles; the separation unit is a gas-liquid cyclone separator, and the gas-liquid cyclone separator comprises 32 gas-liquid cyclone subassembly combinations with a rated flow of 500m 3 / h. The hydrochloric acid regeneration flue gas emission system further comprises a collecting unit; the collecting unit is connected with the absorption unit and a gas-liquid cyclone separator respectively; the gas-liquid cyclone separator stores the liquid beads generated by the gas-liquid cyclone separator in the collecting unit through a first backflow branch. The gas-liquid cyclone separator is a ceramic cyclone separator; the liquid beads condensed by the flue gas cooler are treated by the gas-liquid cyclone separator; the particles and liquid beads with a size of more than 1 mu m are separated and removed from the flue gas at a rate of 100%; the flue gas is introduced into the cooling unit through the absorption unit; the flue gas is cooled by the cooling unit; the hydrogen chloride and water vapor in the flue gas are condensed into liquid beads; the liquid beads are bonded with the iron oxide particles; the liquid beads and the iron oxide particles are introduced into the gas-liquid cyclone separator together with the flue gas; the liquid beads are separated by the gas-liquid cyclone separator; the separated liquid is introduced into the collecting unit; the purified flue gas is introduced into the washing unit; The washing unit is a washing tower; the washing tower adopts a three-section tower body; the bottom of the washing tower is a filler section; a water film absorption section is arranged in the middle of the washing tower; a water film absorption layer is arranged in the water film absorption section; a mist removal device is arranged at the top of the washing tower; the mist removal device is used for ensuring that the water mist in the flue gas is little; the flue gas flows from bottom to top; in the water film absorption layer, desalted water is used as the water film absorption water; the flue gas is purified by the water film absorption in a circulating absorption mode; the water film absorption water spraying flow is adjusted according to the data measured by the monitoring device; when the detected value exceeds the set value, industrial water or desalted water is supplemented; the filler section is washed by the pickling and rinsing water; the pickling and rinsing water is used as the washing water to wash the flue gas; the spraying flow of the washing water is adjusted according to the monitoring device; when the detected value exceeds the set value, the pickling and rinsing water is supplemented.

2. The hydrochloric acid regenerative flue gas emission system of claim 1, wherein, The absorption unit comprises a primary absorption tower and a secondary absorption tower; the collecting unit is connected with the spraying layer at the top of the secondary absorption tower through a second backflow branch; the collecting unit is connected with the spraying layer at the top of the primary absorption tower through a third backflow branch.

3. The hydrochloric acid regeneration flue gas emission system of claim 1, wherein, The flue gas cooler adopts a modified graphite heat exchanger; the flue gas flows from top to bottom.

4. A method of regenerating hydrochloric acid from a flue gas emission, characterized in that, The hydrochloric acid regeneration flue gas emission method comprises the following steps: S1. The 89-97℃ calcination furnace flue gas is introduced into the bottom of the top of the first absorption tower, and the absorption liquid of the top spray layer of the first absorption tower is sprayed downward. Due to the convection of the absorption liquid and the flue gas, the absorption liquid can fully absorb the hydrogen chloride in the flue gas to form regenerated acid. The regenerated acid is discharged from the pipe at the bottom of the first absorption tower and collected; S2. The flue gas treated by the first absorption tower enters the bottom of the second absorption tower. Similarly, the absorption water of the top spray layer of the second absorption tower is sprayed downward, and forms convection with the flue gas flowing upward from the bottom. During the convection process, the absorption water fully absorbs the residual hydrogen chloride and dust particles in the flue gas. The absorption water after absorbing hydrogen chloride and dust particles is discharged from the bottom of the second absorption tower and enters the collection tank. The outlet temperature of the flue gas of the second absorption tower is 82-85℃; S3. The flue gas treated by the second absorption tower enters the flue gas cooler. The flue gas cooler adjusts the circulating water volume by controlling the frequency conversion circulating water pump according to the flue gas treatment capacity of the hydrochloric acid regeneration unit. The outlet flue gas temperature of the flue gas cooler is 55-60℃. At the same time, the flue gas cooler can be regularly online self-cleaning according to the running time of the hydrochloric acid regeneration unit. The working cycle of the flue gas cooler is 240-360 hours; S4. The flue gas cooled by the flue gas cooler enters the gas-liquid cyclone separator. The separated liquid produced by the gas-liquid cyclone separator is discharged into the collection tank. The separated liquid contains a high concentration of hydrogen chloride and iron oxide. The liquid beads condensed by the flue gas cooler are treated by the gas-liquid cyclone separator. Particles and liquid beads above 1μm are 100% separated and removed from the flue gas; S5. The flue gas treated by the gas-liquid cyclone separator passes through the waste gas fan and enters the washing tower. The temperature of the flue gas entering the washing tower is controlled to be 60-65℃; S6. In the washing tower, use pickling rinse water as washing water. Use circulating washing method to wash the flue gas. Adjust the spray flow of the circulating washing water according to the data of the chimney online detector. When the detected value exceeds the set value, add rinse water; S7. In the washing tower, use desalted water as water film absorption water. Use circulating absorption method to absorb and purify the flue gas. Adjust the spray flow of the water film absorption water according to the data measured by the flue gas online monitor arranged on the chimney. When the detected value exceeds the set value, add industrial water or desalted water; S8. The flue gas treated by the washing tower is discharged into the atmosphere through the chimney.

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