Smelting flue gas sulfuric acid purification dilute acid concentration system

Abstract

The utility model belongs to the technical field of waste acid concentration or purification equipment, and particularly relates to a dilute acid concentration system for purifying sulfuric acid in smelting flue gas. The system comprises a secondary absorption tower, a dilute acid discharge tank, a dilute acid concentration tower, a desulfurization tower, a wet-type electric dust remover and a chimney, the lower part of the side wall of the secondary absorption tower is provided with a first gas inlet end, the first gas inlet end is externally connected with a first gas inlet pipe, and the acid-making flue gas enters the secondary absorption tower through the first gas inlet pipe and the first gas inlet end; a second gas inlet end and a liquid inlet end are arranged on the side wall of the dilute acid concentration tower; a first gas outlet end at the top of the secondary absorption tower is communicated with the second gas inlet end on the side wall of the dilute acid concentration tower through a second gas inlet pipe; a liquid outlet end is arranged at the lower part of the dilute acid discharge tank and is connected with a first dilute acid discharge pipe. The device is suitable for the acid-making process in the smelting industry, solves the problems of low dilute acid concentration, large discharge capacity and high treatment cost of a purification system, and realizes the purposes of waste acid concentration and acid-making tail gas heat recovery of a smelting acid-making system.

Description

Technical Field

[0001] This utility model belongs to the technical field of waste acid concentration or purification equipment, specifically relating to a dilute acid concentration system for sulfuric acid purification of smelting flue gas. Background Technology

[0002] Raw materials used in the copper smelting industry often contain moisture, which can easily lead to an increase in moisture content in the flue gas. When high-temperature flue gas is sent to the sulfuric acid purification system after dust removal, it enters the next treatment system after being cooled by wet dust removal. However, because the flue gas contains moisture, some moisture and dust are collected in the purification system, causing an increase in the water volume and dust concentration. This necessitates continuous replenishment of fresh water to replace the circulating liquid in the purification system. After replacement in the purification system, the resulting waste acid is sent to the wastewater treatment system. However, due to the continuous increase in moisture in the purification system, the water volume needs to be continuously discharged for replacement. This results in a decrease in the acidity and an increase in the acid quantity of the discharged waste acid, increasing the difficulty of wastewater treatment, increasing the pressure on system water reuse, and ultimately increasing the cost of waste acid treatment and the overall production cost of the process.

[0003] Based on this, this utility model designs a dilute acid concentration system for sulfuric acid purification of smelting flue gas. By utilizing the residual heat of the flue gas during the drying process and recovering the heat of the flue gas, it is used to concentrate the waste acid, thereby increasing the acidity of the waste acid. At the same time, this utility model system can also recover the water in the waste acid treatment process to reduce production costs. Utility Model Content

[0004] Based on the technical problems existing in the prior art, this utility model proposes a dilute acid concentration system for sulfuric acid purification of smelting flue gas, which is applicable to the acid production process in the smelting industry. It solves the problems of low dilute acid concentration, large discharge volume and high treatment cost in the purification system, and realizes the purpose of concentrating waste acid in the smelting acid production system and recovering heat from the acid production tail gas.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A sulfuric acid purification and dilute acid concentration system for smelting flue gas includes a secondary absorption tower, a dilute acid discharge tank, a dilute acid concentration tower, a desulfurization tower, a wet electrostatic precipitator, and a chimney.

[0007] The lower part of the side wall of the second absorption tower is provided with a first air inlet end, and the first air inlet end is connected to a first air inlet pipe. The acid production flue gas enters the second absorption tower through the first air inlet pipe and the first air inlet end.

[0008] The dilute acid concentration tower has a second air inlet and a liquid inlet on its side wall. The first air outlet at the top of the second absorption tower is connected to the second air inlet on the side wall of the dilute acid concentration tower through the second air inlet pipe.

[0009] The lower part of the dilute acid discharge tank is provided with a liquid outlet and is connected to a first dilute acid discharge pipe. The first dilute acid discharge pipe has two branches, namely the first branch and the second branch. The first branch is connected to the liquid inlet on the side wall of the dilute acid concentration tower. The second branch is connected to an external sewage treatment system.

[0010] The bottom of the dilute acid concentration tower contains dilute acid, and the side wall of the dilute acid concentration tower is connected to a second dilute acid discharge pipe. The second dilute acid discharge pipe has two branches, namely the third branch and the fourth branch.

[0011] The upper part of the dilute acid concentration tower is equipped with two-stage spray pipes; both the upper and lower spray pipes are equipped with atomizing nozzles on their side walls.

[0012] The side wall of the dilute acid concentration tower is also equipped with a level gauge to measure the level of dilute acid inside the tower.

[0013] The second air outlet at the top of the dilute acid concentration tower is connected to the third air inlet on the side wall of the desulfurization tower through the third air inlet pipe;

[0014] The third outlet at the top of the desulfurization tower is connected to the fourth inlet of the wet electrostatic precipitator via the fourth inlet pipe. The fourth outlet at the top of the wet electrostatic precipitator is connected to the fifth inlet of the chimney via the fifth inlet pipe, and environmental emissions are emitted from the top of the chimney.

[0015] Furthermore, the middle section of the second suction tower is provided with a packing layer and a first spray pipe from bottom to top. The input end of the first spray pipe extends out of the second suction tower and is connected to an external spray liquid storage tank.

[0016] Furthermore, a dilute acid discharge valve is provided on the first dilute acid discharge pipe, and a dilute acid discharge pump is also provided at the connection between the first dilute acid discharge pipe and the liquid outlet of the dilute acid discharge tank.

[0017] Furthermore, a first electric valve is installed on the first branch road.

[0018] Furthermore, a second electric valve is installed on the second branch.

[0019] Furthermore, the input ends of both the upper and lower spray pipes extend outside the dilute acid concentration tower, and the third branch is connected to the input end of the lower spray pipe, while the fourth branch is connected to the input end of the upper spray pipe. The flue gas entering the dilute acid concentration tower is atomized and sprayed through the upper and lower spray pipes, thereby increasing the evaporation of water in the waste acid.

[0020] Furthermore, a first dilute acid concentration circulation pump is installed on the third branch, and a second dilute acid concentration circulation pump is installed on the fourth branch.

[0021] Furthermore, the fourth branch is also equipped with a first bypass pipe, which is connected to the second branch; the first bypass pipe is equipped with a third electric valve; the third branch is also equipped with a second bypass pipe, which is connected to the first bypass pipe.

[0022] Furthermore, to enhance ease of use and increase the automation level of the system described in this application, the liquid level gauge is an ultrasonic liquid level gauge with a signal transmitting end and a digital signal output method, such as RS485, Modbus, HART, Foundation, Fieldbus, etc. The liquid level gauge can be a conventional ultrasonic liquid level gauge in the prior art, such as Uson-11, Uson-21, Uson-31, 7ML1201-1EF00, SITRANS Probe LU 7ML5221, etc., and its structure is not the inventive point of this utility model, so it will not be described in detail.

[0023] Furthermore, the system described in this application also includes a PLC controller, which can be installed inside or outside the level gauge; the level gauge measures the liquid level in the dilute acid concentration tower and sends a corresponding digital signal of the liquid level to the PLC controller; the PLC controller performs interlocking control on the opening or closing of the first electric valve, the second electric valve, and the third electric valve respectively. The connection method between the PLC controller and the level gauge in this utility model can adopt existing technology and is not the inventive point of this utility model, so it will not be described in detail.

[0024] Furthermore, the PLC controller includes a digital signal receiving unit, a CPU, an analog signal / digital signal conversion unit, and an analog signal transmitting unit; the first electric valve, the second electric valve, and the third electric valve are all equipped with analog signal receiving terminals;

[0025] Since the PLC controller's CPU has set the highest and lowest threshold values ​​for the liquid level, the PLC controller compares the received digital signal with the highest and lowest threshold values, and then sends an open or close digital signal. The open or close digital signal is then converted into an analog signal and sent to the first, second, and third electric valves, thereby realizing the interlocking cascade control of the first, second, and third electric valves by the DCS control module.

[0026] Specifically, the model and structure of the PLC controller, the model and structure of the first electric valve, the second electric valve and the third electric valve, and the signal connection method between the PLC controller and the first electric valve, the second electric valve and the third electric valve can all adopt conventional settings in the prior art, and are not the inventive point of this utility model, so they will not be described in detail.

[0027] Furthermore, the desulfurization tower has a packing layer and a second spray pipe arranged sequentially from bottom to top in the middle; the bottom of the desulfurization tower is equipped with circulating liquid, and the side wall of the desulfurization tower is connected to the circulating liquid discharge pipe; the input end of the second spray pipe extends out of the desulfurization tower, and the circulating liquid discharge pipe is connected to the input end of the second spray pipe; a desulfurization circulating pump is installed on the circulating liquid discharge pipe.

[0028] Compared with the prior art, the beneficial effects of this utility model are:

[0029] The sulfuric acid purification and dilute acid concentration system for smelting flue gas described in this invention can, to a certain extent, solve the problems of low acidity of dilute acid and high load and difficulty in handling waste acid in existing flue gas purification systems in the smelting industry. It is suitable for acid production systems with low acidity of dilute acid, large waste acid treatment volume, and no heat recovery from dry flue gas. This invention can achieve the purpose of purifying and concentrating dilute acid, reducing the amount of waste acid treated, and simultaneously realizing the recovery and utilization of heat from the dry flue gas outlet.

[0030] This invention designs an acid production system suitable for situations where the heat of the flue gas at the outlet of the second absorption tower cannot be recovered, the treatment of discharged waste acid is difficult, and the acidity of the waste acid is low.

[0031] This invention, by installing a PLC controller, a first electric valve, a second electric valve, and a third electric valve between the dilute acid discharge tank and the dilute acid concentration tower, allows switching the flow of waste acid into the dilute acid concentration tower or an external wastewater treatment system. When the dilute acid concentration tower has a high level or is under maintenance, the electric valves can be switched directly, allowing the waste acid to be discharged directly into the waste acid treatment system. This invention can treat the waste acid generated during the acid production process at any time, solving the problems of low acidity and large discharge volume.

[0032] The system described in this utility model can handle the waste acid generated by the acid production system during the copper smelting process at any time, and can achieve automated operation, control the acid concentration and quantity, discharge the acid quantitatively, and realize online maintenance of the atomizing spray device.

[0033] The system described in this invention is suitable for flue gas with a temperature of 40℃~100℃ and dry flue gas. When the acid production flue gas enters the system described in this invention, it is atomized and sprayed through the upper and lower spray pipes in the dilute acid concentration tower, so that the dilute acid is atomized and comes into contact with the dry flue gas, causing the water in the dilute acid to vaporize, thereby achieving the concentration of dilute acid.

[0034] The system described in this invention is suitable for dry flue gas with high flue gas temperature. It can utilize the characteristics of dry flue gas and the presence of heat to evaporate water in dilute acid, recover and reuse the water in dilute acid, and at the same time achieve effective utilization of heat in flue gas.

[0035] The system described in this invention is suitable for low-acidity dilute acid with a waste acidity of 2% to 10%, and the concentrated acidity can be adjusted according to the volume of flue gas and the water consumption of subsequent processes.

[0036] The system described in this invention can handle flue gas volumes ranging from 0 to 500,000 m³. 3 / h, wherein the first and second dilute acid concentration circulation pumps can be variable frequency pumps, and the spray volume can be adjusted according to the amount of dilute acid and the liquid level, so as to achieve energy saving while meeting the liquid level balance in the dilute acid concentration tower.

[0037] The desulfurization tower in the system of this utility model can recover the water carried away by the flue gas in the dilute acid concentration tower, and at the same time, it can recover part of the dilute acid carried away by the flue gas; the system of this utility model also includes a wet electrostatic precipitator, which can effectively remove acid mist and particulate matter in the flue gas. Attached Figure Description

[0038] Figure 1 This is a schematic diagram of the sulfuric acid purification and dilute acid concentration system for smelting flue gas described in Example 1.

[0039] Among them, 1. Second suction tower, 2. Dilute acid discharge tank, 3. Dilute acid discharge pump, 4. Dilute acid concentration tower, 5. Level gauge, 6. Second dilute acid concentration circulation pump, 7. First dilute acid concentration circulation pump, 8. Desulfurization tower, 9. Desulfurization circulation pump, 10. Wet electrostatic precipitator, 11. Chimney, 12. First electric valve, 13. Second electric valve, 14. Third electric valve, 15. Dilute acid discharge valve, 16. Second branch, 17. Fourth branch, 18. First bypass pipe, 19. Second bypass pipe. Detailed Implementation

[0040] To facilitate understanding of this utility model, the following description will be provided in more comprehensive and detailed manner with reference to the accompanying drawings and preferred embodiments. However, the scope of protection of this utility model is not limited to the following specific embodiments.

[0041] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of protection of this invention.

[0042] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0043] Example 1

[0044] like Figure 1 As shown, a dilute acid concentration system for sulfuric acid purification of smelting flue gas mainly solves, to a certain extent, the problems of the inability to recover flue gas and heat at the outlet of the secondary absorption tower in the existing technology, as well as the difficulty in treating the discharged waste acid and the low acidity of the waste acid. The system includes a dry absorption secondary absorption tower 1 for acid production, a dilute acid discharge tank 2 (made of fiberglass), a dilute acid concentration tower 4 (made of fiberglass), a desulfurization tower 8 (made of fiberglass), a wet electrostatic precipitator 10, and a chimney 11.

[0045] The middle part of the second absorption tower 1 is provided with a packing layer and a first spray pipe from bottom to top. The input end of the first spray pipe extends out of the second absorption tower 1 and is connected to an external spray liquid storage tank. The spray liquid storage tank contains 98% concentrated sulfuric acid. The 98% concentrated sulfuric acid is sprayed through the first spray pipe to absorb sulfur trioxide in the flue gas.

[0046] The lower part of the side wall of the second absorption tower 1 is provided with a first air inlet end, and the first air inlet end is connected to a first air inlet pipe. The acid production flue gas enters the second absorption tower 1 through the first air inlet pipe and the first air inlet end.

[0047] The dilute acid concentration tower 4 has a second air inlet and a liquid inlet on its side wall. The first air outlet at the top of the second absorption tower 1 is connected to the second air inlet on the side wall of the dilute acid concentration tower 4 through the second air inlet pipe.

[0048] The lower part of the dilute acid discharge tank 2 is provided with a liquid outlet and is connected to a first dilute acid discharge pipe. The first dilute acid discharge pipe is provided with a dilute acid discharge valve 15. A dilute acid discharge pump 3 is also provided at the connection between the first dilute acid discharge pipe and the liquid outlet of the dilute acid discharge tank 2. The first dilute acid discharge pipe is provided with two branches, namely the first branch (not shown in the figure) and the second branch 16. The first branch is connected to the liquid inlet of the side wall of the dilute acid concentration tower 4. A first electric valve 12 is provided on the first branch.

[0049] The second branch 16 is connected to an external sewage treatment system, and the second branch 16 is equipped with a second electric valve 13.

[0050] The bottom of the dilute acid concentration tower 4 contains dilute acid (the composition of the dilute acid is dilute sulfuric acid with a mass fraction of 2% to 10%). The side wall of the dilute acid concentration tower 4 is connected to the second dilute acid discharge pipe at the position corresponding to the dilute acid. The second dilute acid discharge pipe has two branches, namely the third branch (not shown in the figure) and the fourth branch 17.

[0051] The upper part of the dilute acid concentration tower 4 is equipped with two-stage spray pipes, and the side walls of both spray pipes are equipped with atomizing nozzles. The input ends of both spray pipes extend outside the dilute acid concentration tower 4, and the third branch is connected to the input end of the lower spray pipe, and the fourth branch 17 is connected to the input end of the upper spray pipe. The flue gas entering the dilute acid concentration tower 4 is atomized and sprayed through the two-stage spray pipes to increase the evaporation of water in the waste acid.

[0052] The third branch is equipped with a first dilute acid concentration circulation pump 7, and the fourth branch 17 is equipped with a second dilute acid concentration circulation pump 6.

[0053] In a further preferred embodiment, the fourth branch 17 is also provided with a first bypass pipe 18, which is connected to the second branch 16; the first bypass pipe 18 is provided with a third electric valve 14; the third branch is also provided with a second bypass pipe 19, which is connected to the first bypass pipe 18.

[0054] A level gauge 5 is also installed on the side wall of the dilute acid concentration tower 4, corresponding to the position of the bottom dilute acid, to measure the level of dilute acid in the dilute acid concentration tower 4.

[0055] Furthermore, to enhance ease of use and increase the automation level of the system described in this application, the level gauge 5 is an ultrasonic level gauge with a signal transmitting end and a digital signal output method, such as RS485, Modbus, HART, Foundation, Fieldbus, etc. The level gauge can be a conventional ultrasonic level gauge in the prior art, such as Uson-11, Uson-21, Uson-31, 7ML1201-1EF00, SITRANS Probe LU 7ML5221, etc., and its structure is not the inventive point of this utility model, so it will not be described in detail.

[0056] Meanwhile, the system described in this application also includes a PLC controller, which can be installed inside or outside the level gauge 5. The PLC controller can interlock the opening and closing of the first electric valve 12, the second electric valve 13, and the third electric valve 14 respectively. The connection method between the PLC controller and the level gauge 5 can be achieved using existing technology and is not the inventive point of this utility model, so it will not be described in detail.

[0057] In practical use, the PLC controller includes a digital signal receiving unit, a CPU, an analog signal / digital signal conversion unit, and an analog signal transmitting unit; the first electric valve 12, the second electric valve 13, and the third electric valve 14 are all equipped with analog signal receiving terminals;

[0058] The liquid level in the dilute acid concentration tower 4 is measured by the level gauge 5, and a digital signal of the corresponding liquid level is sent to the PLC controller. Since the CPU of the PLC controller has a maximum and minimum threshold for the liquid level, the PLC controller compares the received digital signal with the maximum and minimum thresholds, and then sends an open or close digital signal. The open or close digital signal is then converted into an analog signal and sent to the first electric valve 12, the second electric valve 13, and the third electric valve 14 to achieve interlocking cascade control of the first electric valve 12, the second electric valve 13, and the third electric valve 14 by the DCS control module.

[0059] Specifically, the model and structure of the PLC controller, the model and structure of the first electric valve 12, the second electric valve 13 and the third electric valve 14, and the signal connection method between the PLC controller and the first electric valve 12, the second electric valve 13 and the third electric valve 14 can all adopt conventional settings in the prior art, and are not the inventive point of this utility model, so they will not be described in detail.

[0060] The second air outlet at the top of the dilute acid concentration tower 4 is connected to the third air inlet on the side wall of the desulfurization tower 8 through the third air inlet pipe;

[0061] The desulfurization tower 8 has a packing layer and a second spray pipe arranged sequentially from bottom to top in the middle section; the bottom of the desulfurization tower 8 is equipped with circulating liquid (the circulating liquid is 0.2%-1% hydrogen peroxide, and the acidity is 5%-10%), and the side wall of the desulfurization tower 8 is connected to the circulating liquid discharge pipe; the inlet end of the second spray pipe extends out of the desulfurization tower 8, and the circulating liquid discharge pipe is connected to the inlet end of the second spray pipe; a desulfurization circulating pump 9 is installed on the circulating liquid discharge pipe;

[0062] The third air outlet at the top of the desulfurization tower 8 is connected to the fourth air inlet of the wet electrostatic precipitator 10 through the fourth air inlet pipe. The fourth air outlet at the top of the wet electrostatic precipitator 10 is connected to the fifth air inlet of the chimney 11 through the fifth air inlet pipe. Environmental emissions are emitted from the top of the chimney 11.

[0063] The wet electrostatic precipitator 10 can be a conventional model of equipment in the existing technology, and it is not the point of invention of this utility model, so it will not be described in detail.

[0064] In the system described in this utility model, the waste acid discharged from the copper smelting process purification system enters the dilute acid discharge tank 2 and is then sent to the dilute acid concentration tower 4. The waste acid is atomized by the first dilute acid concentration circulation pump 7 and the second dilute acid concentration circulation pump 6 into the upper and lower spray pipes. The atomized waste acid comes into full contact with the dry flue gas that enters the dilute acid concentration tower 4. The water in the waste acid vaporizes and is carried by the flue gas into the subsequent desulfurization tower 8 as makeup water for the desulfurization tower 8.

[0065] After the waste acid is concentrated by the moisture carried away by the flue gas, it can be sent to the sewage treatment system for further treatment through the first bypass pipe 18, the second bypass pipe 19, and the second branch pipe 16.

[0066] The dilute acid level in the dilute acid concentration tower 4 is measured by the level gauge 5. The level gauge 5 is interlocked with the first electric valve 12, the second electric valve 13 and the third electric valve 14 through the PLC controller. When the level in the dilute acid concentration tower 4 is too low or too high, the PLC controller controls the opening or closing of the first electric valve 12, the second electric valve 13 and the third electric valve 14 to adjust the dilute acid level.

[0067] When the first dilute acid concentration circulation pump 7 and the second dilute acid concentration circulation pump 6 or the atomizing nozzles of the upper and lower spray pipes fail, the waste acid can be directly discharged through the first bypass pipe 18, the second bypass pipe 19 and the second branch pipe 16, and will no longer enter the dilute acid concentration tower 4.

[0068] The dilute acid concentration tower 4 uses upper and lower spray pipes for atomization, which allows the flue gas to fully contact the waste acid, increasing the evaporation of water from the waste acid. The dilute acid concentration tower 4 has no packing material inside, which reduces system resistance and saves overall system energy consumption.

[0069] In addition, a water collection structure or a filtration structure can be installed at the upper part of the dilute acid concentration tower 4 to prevent unevaporated waste acid from being directly carried away by the flue gas.

[0070] The smelting flue gas sulfuric acid purification and dilute acid concentration system of this utility model, during operation, the waste acid discharged from the purification system enters the dilute acid discharge tank 2 after being filtered by pressure. At this time, the temperature is basically maintained at 40-60℃, and it is directly sent into the dilute acid concentration tower 4 without passing through the heat exchange system. At the same time, after the smelting flue gas passes through the dry absorption system to dry the moisture and absorb sulfur trioxide, the flue gas temperature is basically maintained at 50-70℃, and it can be sent into the dilute acid concentration tower 4. The higher the temperature, the more obvious the evaporation effect.

[0071] Inside the dilute acid concentration tower 4, the temperature of the dry flue gas is slightly higher than that of the waste acid. The waste acid is heated and evaporated by the flue gas, which increases the acidity of the waste acid. The water is carried into the desulfurization tower 8 by the flue gas and used as makeup water for the desulfurization tower 8.

[0072] The concentrated waste acid can be directly discharged through the first bypass pipe 18, the second bypass pipe 19, and the second branch pipe 16, without the need to install a separate discharge pump.

[0073] The dilute acid concentration tower 4 is made entirely of fiberglass, and its supporting pipes, valves, pumps, and upper and lower spray pipes are all made of corrosion-resistant materials to prevent dilute acid from corroding the equipment.

[0074] The operating mode of this utility model is as follows:

[0075] 1) Acid production flue gas (the flue gas temperature before entering the second absorption tower 1 is 170℃, the main components of which include 1% sulfur trioxide and 300mg / Nm³) 3 Sulfur dioxide is absorbed and treated by the second absorption tower 1, and its temperature drops to 50-80℃ before entering the dilute acid concentration tower 4. At the same time, dilute acid at 40-60℃ discharged from the purification system is introduced into the dilute acid discharge tank 2. At this time, the dilute acid discharge valve 15 and the first electric valve 12 are manually opened, and the second electric valve 13 and the third electric valve 14 are closed. The dilute acid discharge pump 3 is used to send the dilute acid through the first dilute acid discharge pipe into the dilute acid concentration tower 4. After entering the dilute acid concentration tower 4, the dilute acid is collected at the bottom of the dilute acid concentration tower 4. The dilute acid is then pumped into the upper and lower spray pipes by the second dilute acid concentration circulation pump 6 and the first dilute acid concentration circulation pump 7, respectively, to perform two-stage atomization spraying on the flue gas entering the dilute acid concentration tower 4 from the second absorption tower 1. The flue gas and dilute acid come into countercurrent contact in the dilute acid concentration tower 4. The dry flue gas causes the water in the dilute acid to vaporize. At this time, the temperature of the acid production flue gas drops to about 40℃.

[0076] 2) The cooled and concentrated flue gas then enters the desulfurization tower 8 through the third inlet pipe for desulfurization. Simultaneously, the circulating liquid in the desulfurization tower 8 is pumped into the second spray pipe by the desulfurization circulation pump 9 to contact the flue gas in a counter-current manner, treating the pollutants in the flue gas (the main component of the pollutants is 300 mg / Nm³). 3 The sulfur dioxide in the flue gas after treatment (including sulfur dioxide) is partially liquefied and collected in desulfurization tower 8, and the sulfur dioxide content in the flue gas after treatment in desulfurization tower 8 is less than 50 mg / Nm³. 3 Then it enters the wet electrostatic precipitator 10 for demisting and dust removal, and finally is sent into the chimney 11 for emission in compliance with standards.

[0077] 3) In this utility model, the liquid level gauge 5, the PLC controller, and the first electric valve 12, the second electric valve 13, and the third electric valve 14 are interlocked to control the liquid inlet and outlet of the dilute acid concentration tower 4, specifically:

[0078] A level gauge 5 is used to detect the liquid level in the dilute acid concentration tower 4 and sends a digital signal of the corresponding liquid level to the PLC controller. Since the CPU of the PLC controller has a maximum and minimum threshold for the liquid level, the PLC controller compares the received digital signal with the maximum and minimum thresholds and then sends an open or close digital signal. The open or close digital signal is then converted into an analog signal and sent to the first electric valve 12, the second electric valve 13 and the third electric valve 14 to achieve interlocking cascade control of the first electric valve 12, the second electric valve 13 and the third electric valve 14 by the DCS control module.

[0079] In the specific control process, the first electric valve 12 and the third electric valve 14 are opened first, and the second electric valve 13 is closed, so that the dilute acid in the dilute acid discharge tank 2 enters the dilute acid concentration tower 4.

[0080] When the level gauge 5 sends the level digital signal to the PLC controller, the PLC controller calculates that when the level value reaches or exceeds the preset maximum threshold, the PLC controller sends an open or close digital signal and converts the open or close digital signal into an analog signal, interlocking the second electric valve 13 to open and the first electric valve 12 and the third electric valve 14 to close, so that the dilute acid is directly discharged to the sewage treatment system through the second branch 16.

[0081] When the level gauge 5 sends the level digital signal to the PLC controller, the PLC controller calculates that when the level value is lower than the preset minimum threshold, the PLC controller sends an open or close digital signal and converts the open or close digital signal into an analog signal, interlocking to close the second electric valve 13 and the third electric valve 14, so that the dilute acid enters the dilute acid concentration tower 4 for self-circulation to increase the acid concentration.

[0082] In addition, when the liquid level in the desulfurization tower 8 is too high, the atomization spraying effect in the dilute acid concentration tower 4 can be controlled by turning on or off the first dilute acid concentration circulation pump 7 and the second dilute acid concentration circulation pump 6, or by adjusting the degree of opening of the first dilute acid concentration circulation pump 7 and the second dilute acid concentration circulation pump 6, thereby reducing the moisture carried away by the flue gas and ensuring the normal operation of the process.

[0083] Application Examples

[0084] Taking a copper smelting production enterprise as an example, the copper smelting sulfuric acid production system has a 10% moisture content in the ore powder. This moisture, introduced into the system at high temperatures, liquefies and accumulates during cooling. Furthermore, the acid purification system requires continuous filtration of waste acid, resulting in excess water in the purification system. Due to constant replacement, the acidity of the dilute acid is low, leading to a large volume of difficult-to-treat wastewater discharged to the sewage treatment system. After modification, the smelting flue gas sulfuric acid purification and dilute acid concentration system described in this application was added to the original sulfuric acid production system, which can reduce the daily discharge of dilute acid from 400 m³ / day. 3 Acidity 2%~10%, reduced to 100m 3 ~200m 3 With an acidity of 6%–30%, it effectively reduces the pressure on the wastewater treatment system, while the downstream desulfurization tower can reduce water consumption by approximately 50 cubic meters per day. 3 This provides an effective guarantee for the normal operation of the system.

[0085] The system described in this utility model has a simple structure and is easy to operate. It can be applied to various smelting flue gas purification systems and acid concentration systems.

[0086] In the description of this utility model, it should be noted that the directional terms such as "center", "horizontal", "longitudinal", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", and "counterclockwise" indicate the orientation and positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. They should not be construed as limiting the specific protection scope of this utility model.

[0087] It should be noted that the terms "first," "second," etc., used in the specification and claims of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be used interchangeably where appropriate for the embodiments of this application described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0088] Finally, it should be noted that the above are merely preferred embodiments and application principles of this utility model. Those skilled in the art will understand that this utility model is not limited to the specific embodiments described herein, and various obvious changes, readjustments, and substitutions can be made without departing from the protection scope of this utility model. Therefore, although the utility model has been described in detail through the above embodiments, it is not limited to the specific embodiments described herein. Many other effective embodiments may be included without departing from the concept of this utility model, and the scope of this utility model is determined by the scope of the appended claims.

Claims

1. A dilute acid concentration system for sulfuric acid purification of smelting flue gas, characterized in that, This includes a secondary suction tower, a dilute acid discharge tank, a dilute acid concentration tower, a desulfurization tower, a wet electrostatic precipitator, and a chimney; The lower part of the side wall of the second absorption tower is provided with a first air inlet end, and the first air inlet end is connected to a first air inlet pipe. The acid production flue gas enters the second absorption tower through the first air inlet pipe and the first air inlet end. The dilute acid concentration tower has a second air inlet and a liquid inlet on its side wall. The first air outlet at the top of the second absorption tower is connected to the second air inlet on the side wall of the dilute acid concentration tower through the second air inlet pipe. The lower part of the dilute acid discharge tank is provided with a liquid outlet and is connected to a first dilute acid discharge pipe. The first dilute acid discharge pipe has two branches, namely the first branch and the second branch. The first branch is connected to the liquid inlet on the side wall of the dilute acid concentration tower. The second branch is connected to an external sewage treatment system. The bottom of the dilute acid concentration tower contains dilute acid, and the side wall of the dilute acid concentration tower is connected to a second dilute acid discharge pipe. The second dilute acid discharge pipe has two branches, namely the third branch and the fourth branch. The upper part of the dilute acid concentration tower is equipped with two-stage spray pipes; both the upper and lower spray pipes are equipped with atomizing nozzles on their side walls. The side wall of the dilute acid concentration tower is also equipped with a level gauge to measure the level of dilute acid inside the tower. The second air outlet at the top of the dilute acid concentration tower is connected to the third air inlet on the side wall of the desulfurization tower through the third air inlet pipe; The third outlet at the top of the desulfurization tower is connected to the fourth inlet of the wet electrostatic precipitator via the fourth inlet pipe. The fourth outlet at the top of the wet electrostatic precipitator is connected to the fifth inlet of the chimney via the fifth inlet pipe, and environmental emissions are emitted from the top of the chimney.

2. The smelting flue gas sulfuric acid purification and dilute acid concentration system according to claim 1, characterized in that, The middle section of the second suction tower is equipped with a packing layer and a first spray pipe, arranged from bottom to top.

3. The smelting flue gas sulfuric acid purification and dilute acid concentration system according to claim 1, characterized in that, The first dilute acid discharge pipe is equipped with a dilute acid discharge valve, and a dilute acid discharge pump is also provided at the connection between the first dilute acid discharge pipe and the liquid outlet of the dilute acid discharge tank.

4. The smelting flue gas sulfuric acid purification and dilute acid concentration system according to claim 1, characterized in that, The first branch road is equipped with a first electric valve; the second branch road is equipped with a second electric valve.

5. The smelting flue gas sulfuric acid purification and dilute acid concentration system according to claim 1, characterized in that, The input ends of both the upper and lower spray pipes extend outside the dilute acid concentration tower, and the third branch is connected to the input end of the lower spray pipe, while the fourth branch is connected to the input end of the upper spray pipe.

6. The smelting flue gas sulfuric acid purification and dilute acid concentration system according to claim 1, characterized in that, The third branch is equipped with the first dilute acid concentration circulation pump, and the fourth branch is equipped with the second dilute acid concentration circulation pump.

7. The smelting flue gas sulfuric acid purification and dilute acid concentration system according to claim 1, characterized in that, The fourth branch is also equipped with a first bypass pipe, which is connected to the second branch; the first bypass pipe is equipped with a third electric valve; the third branch is also equipped with a second bypass pipe, which is connected to the first bypass pipe.

8. The smelting flue gas sulfuric acid purification and dilute acid concentration system according to claim 1, characterized in that, The level gauge is an ultrasonic level gauge with a signal transmitting end and uses digital signal output.

9. The smelting flue gas sulfuric acid purification and dilute acid concentration system according to claim 1, characterized in that, The system also includes a PLC controller; the liquid level in the dilute acid concentration tower is measured by a level gauge and a digital signal of the corresponding liquid level is sent to the PLC controller; the opening or closing of the first electric valve, the second electric valve and the third electric valve are interlocked and controlled by the PLC controller.

10. The smelting flue gas sulfuric acid purification and dilute acid concentration system according to claim 1, characterized in that, The bottom of the desulfurization tower is equipped with circulating liquid, and the side wall of the desulfurization tower is connected to the circulating liquid discharge pipe; the circulating liquid discharge pipe is equipped with a desulfurization circulating pump.

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