Recovery system and method for treating waste sulfuric acid waste liquid containing hydrogen peroxide

Abstract

The invention provides a recycling system and method for treating waste sulfuric acid waste liquid containing hydrogen peroxide. The recycling system for the waste sulfuric acid waste liquid comprises a preheating subsystem, a reaction circulation control subsystem and a cooling subsystem. The preheating subsystem heats the waste sulfuric acid liquid to a preset temperature in a circulating heat exchange mode, and then the temperature is increased to a target temperature through an acid-resistant heater. The reaction circulation control subsystem monitors the sulfuric acid concentration, the hydrogen peroxide content, the reaction temperature and the nitrate compound content of the waste sulfuric acid liquid and determines the adding amount and the adding mode of the nitrate-containing reaction accelerant. And the cooling subsystem exchanges waste heat to the initial sulfuric acid waste liquid through a cooling heat exchanger for recycling the waste sulfuric acid waste liquid, and then the waste sulfuric acid waste liquid after reaction is cooled below the recovery temperature through another cooling heat exchanger, so that the work safety doubt of overheating is avoided.

Description

Technical Field

[0001] The invention relates to a system for recovering waste sulfuric acid liquid containing hydrogen peroxide, which can effectively shorten the treatment time of waste sulfuric acid liquid, reduce the treatment cost and improve the quality of recovered sulfuric acid solution. Background Art

[0002] The prior art uses hydrochloric acid as a promoter, and the reaction time for decomposing hydrogen peroxide is about 11 hours. Since the treatment of waste sulfuric acid waste liquid and the reaction promoter are exothermic reactions, the treatment temperature is too high, and the high temperature leads to industrial safety concerns such as explosion or gas explosion. In addition, the prior art also has the problem of low recovery rate or poor recovery quality. It is impossible to ensure that the waste sulfuric acid waste liquid meets the standards when it flows out, so it cannot be directly recycled and used, and can only be treated as waste liquid and exiled.

[0003] In summary, the inventors of the present invention have thought about and designed a waste sulfuric acid and waste liquid recovery system to improve the deficiencies of the prior art and solve the problems faced by the industry. Summary of the invention

[0004] In view of the above problems existing in the prior art, the present invention proposes a mode of replacing the waste sulfuric acid and waste liquid recovery system with a mode of adding nitric acid and circulating heat exchange, which can achieve the effects of improving reaction efficiency, ensuring recovery quality and avoiding excessive temperature during the treatment process.

[0005] The present invention provides a system for recovering waste sulfuric acid waste liquid containing hydrogen peroxide, comprising:

[0006] A preheating subsystem comprises a waste sulfuric acid preheating treatment tank and an acid-resistant heater, wherein the waste sulfuric acid preheating treatment tank is connected to the acid-resistant heater; a reaction cycle control subsystem comprises a reaction tank, wherein the reaction tank is connected to the acid-resistant heater, and the reaction tank is used to receive a reaction accelerator; a cooling subsystem comprises a first cooling heat exchanger and a second cooling heat exchanger, wherein one end of the first cooling heat exchanger is connected to the reaction tank, and the other end is connected to the second cooling heat exchanger; and a sulfuric acid storage tank is connected to the second cooling heat exchanger; wherein initial waste sulfuric acid waste liquid is injected into the preheating subsystem from a waste sulfuric acid supply source, flows through the reaction cycle control subsystem, reacts with the reaction accelerator to form a sulfuric acid solution, and then flows through the cooling subsystem for treatment to become a recovered sulfuric acid solution and is stored in the sulfuric acid storage tank.

[0007] Preferably, the preheating treatment waste sulfuric acid tank is used to preliminarily heat the injected initial waste sulfuric acid waste liquid to a preheating temperature of 50-60°C, and then flows into the acid-resistant heater, and the acid-resistant heater is used to heat to a target temperature of 70-80°C.

[0008] Preferably, the waste sulfuric acid waste liquid recovery system further includes: a first cold exchange pipeline, which is connected to the waste sulfuric acid supply source and extends through the first cooling heat exchanger and then connected to the preheat treatment waste sulfuric acid tank, so that the sulfuric acid solution in the first cooling heat exchanger is cooled by circulating the initial waste sulfuric acid waste liquid at room temperature in the first cold exchange pipeline.

[0009] Preferably, the waste sulfuric acid waste liquid recovery system further includes: a second cold exchange pipeline, which is connected to cooling water and extends outside the second cooling heat exchanger, so that the second cooling heat exchanger uses the cooling water to cool the sulfuric acid solution to be recovered to the recovery temperature to form the recovered sulfuric acid solution.

[0010] Preferably, the waste sulfuric acid waste liquid recovery system further includes: a heat exchange pipeline, which is connected to the first cooling heat exchanger and extends through the preheat treatment waste sulfuric acid tank and then connected to the second cooling heat exchanger, so that the initial waste sulfuric acid waste liquid in the preheat treatment waste sulfuric acid tank is heated by circulating the high-temperature sulfuric acid solution in the heat exchange pipeline.

[0011] Preferably, the waste sulfuric acid waste liquid recovery system further comprises: a detection device, which is connected to the reaction tank, and is used to monitor the sulfuric acid concentration, hydrogen peroxide content, reaction temperature and nitrate compound content of the waste sulfuric acid waste liquid, and determine the addition amount and addition mode of the reaction accelerator.

[0012] Preferably, the reaction accelerator is a nitric acid additive, such as nitric acid, and an auxiliary agent may be added as required.

[0013] Preferably, the reaction accelerator is 70% nitric acid purchased from the market, so that the sulfuric acid waste liquid contains 500-600 ppm of nitric acid, and the residual nitric acid in the final product after the reaction is <300 ppm.

[0014] Preferably, the adding mode includes: a first mode and / or a second mode, wherein the first mode is to simultaneously inject the heated initial waste sulfuric acid waste liquid and the reaction accelerator into the reaction tank for reaction, and the second mode is to first inject the heated initial waste sulfuric acid waste liquid to the liquid level, and then add the reaction accelerator into the reaction tank for reaction.

[0015] Preferably, the sulfuric acid concentration of the waste sulfuric acid waste liquid is greater than 55wt.%, and the hydrogen peroxide concentration of the waste sulfuric acid waste liquid is below 10wt.%.

[0016] Preferably, the permissible residual amount of hydrogen peroxide in the sulfuric acid solution is below 30 ppm, and the permissible residual amount of nitric acid is below 200-400 ppm.

[0017] Preferably, the waste sulfuric acid waste liquid recovery system further includes: at least one backup waste sulfuric acid waste liquid recovery system, which includes: a backup preheating subsystem, a backup reaction cycle control subsystem and a backup cooling subsystem, which are used to circulate and cool the overheated sulfuric acid solution or serve as a backup system.

[0018] Preferably, the backup preheating subsystem is connected to the reaction cycle control subsystem, and the preheating subsystem is connected to the backup reaction cycle control subsystem.

[0019] The present invention also provides a method for recovering waste sulfuric acid waste liquid containing hydrogen peroxide, which comprises: injecting initial waste sulfuric acid waste liquid containing hydrogen peroxide from a waste sulfuric acid supply source into a preheating waste sulfuric acid tank of a preheating subsystem, heating the initial waste sulfuric acid waste liquid to a preheating temperature by a circulating heat exchange method, and then injecting the acid-resistant heater of the preheating subsystem to raise the temperature to a target temperature; injecting the heated initial waste sulfuric acid waste liquid into a reaction barrel tank in a reaction cycle control subsystem, and adding a reaction accelerator to react to form a sulfuric acid solution; and injecting the sulfuric acid solution into the first cooling heat exchanger of the cooling subsystem to cool the low-temperature initial waste sulfuric acid waste liquid through circulation, and cooling the sulfuric acid solution to be recovered to a recovery temperature through the second cooling heat exchanger with cooling water to form a recovered sulfuric acid solution.

[0020] Preferably, the method for recovering waste sulfuric acid waste liquid further includes: the waste sulfuric acid supply source is connected to the first cold exchange pipeline and extends through the first cooling heat exchanger and then connected to the preheat treatment waste sulfuric acid tank, so that the sulfuric acid solution in the first cooling heat exchanger is cooled by circulating the low-temperature initial waste sulfuric acid waste liquid in the first cold exchange pipeline.

[0021] Preferably, the method for recovering waste sulfuric acid waste liquid further includes: the first cooling heat exchanger is connected to a heat exchange pipeline and extends through the outside of the preheat treatment waste sulfuric acid tank and then connected to the second cooling heat exchanger, so that the initial waste sulfuric acid waste liquid in the preheat treatment waste sulfuric acid tank is heated by circulating the high-temperature sulfuric acid solution in the heat exchange pipeline.

[0022] Preferably, the waste sulfuric acid waste liquid recovery method further includes: connecting at least one backup waste sulfuric acid waste liquid recovery system to the waste sulfuric acid supply source, connecting the backup preheating subsystem of the backup waste sulfuric acid waste liquid recovery system to the reaction cycle control subsystem, and connecting the backup reaction cycle control subsystem of the backup waste sulfuric acid waste liquid recovery system to the preheating subsystem, thereby circulating the overheated sulfuric acid solution for cooling or using it as a backup system. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 Shown is a schematic diagram of a system for recovering waste sulfuric acid waste liquid containing hydrogen peroxide according to the present invention;

[0024] Figure 2 Shown is a schematic diagram of a system for recovering waste sulfuric acid waste liquid containing hydrogen peroxide according to the present invention;

[0025] Figure 3 Shown is a flow chart of the method for treating waste sulfuric acid waste liquid containing hydrogen peroxide and recovering the same according to the present invention.

[0026] Reference numerals:

[0027] 1. Main waste sulfuric acid waste liquid recovery system; 2. Preheating subsystem; 3. Reaction cycle control subsystem; 4. Cooling subsystem; 5. Backup waste sulfuric acid waste liquid recovery system; 6. Backup preheating subsystem; 7. Backup reaction cycle control subsystem; 8. Backup cooling subsystem; 9. Waste sulfuric acid supply source; 10. Preheating waste sulfuric acid tank; 11. Acid-resistant heater; 12. Reaction tank; 120. Detection device; 13. First cooling heat exchanger; 14. Second cooling heat exchanger; 1 5. Sulfuric acid storage tank; 20. Spare preheat treatment waste sulfuric acid tank; 21. Spare acid-resistant heater; 22. Spare reaction tank; 220. Spare detection device; 23. Spare first cooling heat exchanger; 24. Spare second cooling heat exchanger; 25. Spare sulfuric acid storage tank; 31. First cold exchange pipeline; 32. Heat exchange pipeline; 33. Second cold exchange pipeline; 41. Spare first cold exchange pipeline; 42. Spare heat exchange pipeline; 100. Waste sulfuric acid waste liquid recovery system. DETAILED DESCRIPTION

[0028] Several examples are listed below to illustrate the implementation of the system for recovering sulfuric acid waste liquid containing hydrogen peroxide of the present invention, so those skilled in the art can simply understand the advantages and effects that can be achieved by the present invention through the contents of the following examples. It should be understood that the examples listed in this specification are only used to illustrate the implementation of the present invention, and are not used to limit the scope of the present invention. Those skilled in the art can make various modifications and changes based on common knowledge without departing from the spirit of the present invention to implement or apply the content of the present invention.

[0029] Please refer to Figure 1 , which is a schematic diagram of a system 100 for recovering waste sulfuric acid waste liquid containing hydrogen peroxide according to the present invention. Figure 1As shown, the waste sulfuric acid waste liquid recovery system 100 of the present invention comprises a main waste sulfuric acid waste liquid recovery system 1 and at least one backup waste sulfuric acid waste liquid recovery system 5, wherein the main waste sulfuric acid waste liquid recovery system 1 comprises: a preheating subsystem 2, a reaction cycle control subsystem 3 and a cooling subsystem 4; the backup waste sulfuric acid waste liquid recovery system 5 comprises: a backup preheating subsystem 6, a backup reaction cycle control subsystem 7 and a backup cooling subsystem 8. In order to make the description concise and easy to understand, the present invention takes the above-mentioned backup waste sulfuric acid waste liquid recovery system as an example, but is not limited thereto, and two, three or more backup waste sulfuric acid waste liquid recovery systems can actually be set.

[0030] The preheating subsystem 2 comprises a waste sulfuric acid preheating treatment tank 10 and an acid-resistant heater 11 , wherein the waste sulfuric acid preheating treatment tank 10 is connected to the acid-resistant heater 11 ; the backup preheating subsystem 6 comprises a backup waste sulfuric acid preheating treatment tank 20 and a backup acid-resistant heater 21 , wherein the backup preheating treatment waste sulfuric acid tank 20 is connected to the backup acid-resistant heater 21 .

[0031] The reaction cycle control subsystem 3 has a reaction tank 12, which is connected to the acid-resistant heater 11 and is also connected to a detection device 120; the backup reaction cycle control subsystem 7 has a backup reaction tank 22, which is connected to the backup acid-resistant heater 21 and is also connected to a backup detection device 220.

[0032] The cooling subsystem 4 has a first cooling heat exchanger 13 and a second cooling heat exchanger 14, one end of the first cooling heat exchanger 13 is connected to the reaction tank 12, and the other end is connected to the second cooling heat exchanger 14; and a sulfuric acid storage tank 15, connected to the second cooling heat exchanger 14; the backup cooling subsystem 8 has a backup first cooling heat exchanger 23 and a backup second cooling heat exchanger 24, one end of the backup first cooling heat exchanger 23 is connected to the backup reaction tank 22, and the other end is connected to the backup second cooling heat exchanger 24; and a backup sulfuric acid storage tank 25, connected to the backup second cooling heat exchanger 24.

[0033] The detection device 120 and the backup detection device 220 monitor the sulfuric acid concentration of the waste sulfuric acid waste liquid by the specific gravity method known in the art, detect the hydrogen peroxide content by the titration method known in the art, detect the nitrate compound content by the spectrophotometry method known in the art, measure the reaction temperature by a thermometer, and determine the addition amount and addition mode of the reaction accelerator. The initial sulfuric acid concentration of the waste sulfuric acid waste liquid is greater than 55wt.%, the concentration of the hydrogen peroxide solution is below 10wt.% or between 2wt.% and 6wt.%, and the concentration of nitric acid is about 500 to 600ppm. The detection device 120 and the backup detection device 220 adjust the addition amount and addition mode of the reaction accelerator until the sulfuric acid concentration of the sulfuric acid solution after the final reaction is 55wt.% to 85wt.%, the concentration of the hydrogen peroxide solution is below 30ppm, and the concentration of nitric acid is below 200 to 400ppm.

[0034] like Figure 1 As shown, the initial waste sulfuric acid waste liquid will be injected from the waste sulfuric acid supply source 9 into the preheating subsystem 2 for heating, and then flow through the reaction cycle control subsystem 3 to form a sulfuric acid solution, and then flow through the cooling subsystem 4 for cooling to become a recovered sulfuric acid solution stored in the sulfuric acid storage tank 15; the initial waste sulfuric acid waste liquid can also be injected from the waste sulfuric acid supply source 9 into the backup preheating subsystem 6 for heating, and then flow through the backup reaction cycle control subsystem 7 to form a sulfuric acid solution, and then flow through the backup cooling subsystem 8 for cooling to become a recovered sulfuric acid solution stored in the backup sulfuric acid storage tank 25.

[0035] In addition, the backup waste sulfuric acid waste liquid recovery system 5 can circulate and cool the overheated sulfuric acid solution in the main waste sulfuric acid waste liquid treatment system 1 or be used as a backup system.

[0036] Please refer to Figure 2 The main waste sulfuric acid waste liquid recovery system 1 of the present invention is to inject the initial waste sulfuric acid waste liquid containing hydrogen peroxide (i.e., the waste acid to be treated) at room temperature from the waste sulfuric acid supply source 9 into the preheating waste sulfuric acid tank 10, and then flow into the acid-resistant heater 11 to be heated to the target temperature of 80°C, and then flow into the reaction tank 12, and inject a reaction accelerator at the same time. Since the reaction heat is released instantly during the reaction of hydrogen peroxide, while the temperature rises rapidly, the newly injected waste sulfuric acid waste liquid with a lower temperature will cool down, so that the instantaneous temperature rise will be slowed down.

[0037] After the reaction, the high-temperature sulfuric acid solution is heat recovered by the first cooling heat exchanger 13. The first cooling heat exchanger 13 is connected to the heat exchange pipeline 32, so that the high-temperature sulfuric acid solution after the reaction circulates through the heat exchange pipeline 32 through the outside of the preheating treatment waste sulfuric acid tank 10, and the room temperature waste sulfuric acid waste liquid in the preheating treatment waste sulfuric acid tank 10 is heated to the preheating temperature (i.e., 50-60°C) by the high-temperature sulfuric acid solution to achieve equilibrium, thereby reducing the preheating time. At the same time, the high-temperature sulfuric acid solution in the heat exchange pipeline 32 is cooled due to heat exchange. Then, the heat exchange pipeline 32 and the first cooling heat exchanger 13 will inject the cooled sulfuric acid solution into the second cooling heat exchanger 14 for cooling again.

[0038] Cooling recovery water is introduced into the second cold exchange pipeline 33 and flows through the outside of the second cooling heat exchanger 14 through the second cold exchange pipeline 33 to cool the high-temperature sulfuric acid solution in the second cooling heat exchanger 14 to the recovery temperature, and finally the recovered sulfuric acid solution is formed and injected into the sulfuric acid storage tank 15 for storage.

[0039] When the temperature of the sulfuric acid solution after the reaction in the first cooling heat exchanger 13 is too high, the waste sulfuric acid supply source 9 is connected to the first cold exchange pipeline 31, so that the initial waste sulfuric acid waste liquid at room temperature circulates through the first cold exchange pipeline 31 through the outside of the first cooling heat exchanger 13, and the superheated sulfuric acid solution in the first cooling heat exchanger 13 is cooled down to equilibrium by the initial waste sulfuric acid waste liquid at room temperature. At the same time, the initial waste sulfuric acid waste liquid in the first cold exchange pipeline 31 is heated due to heat exchange, and the initial waste sulfuric acid waste liquid in the first cold exchange pipeline 31 is finally injected into the preheating treatment waste sulfuric acid tank 10, thereby making full use of the waste heat of the sulfuric acid solution after the reaction, reducing the energy consumption and cost of heating and cooling, and achieving the effect of energy saving and carbon reduction.

[0040] In addition, the waste sulfuric acid waste liquid recovery system 100 is designed to have two or more production lines, namely, a main waste sulfuric acid waste liquid recovery system 1 and at least one backup waste sulfuric acid waste liquid recovery system 5. When the temperature of one of the production lines is too high, the waste sulfuric acid waste liquid recovery system 100 can be circulated to the second production line for cooling, and can also serve as a backup production line to avoid complete shutdown of production due to failure.

[0041] Specifically, the acid-resistant heater 11 is further connected to the backup reaction tank 22, and the backup acid-resistant heater 21 is further connected to the reaction tank 12. When the reaction tank 12 of the main production line stops due to overheating or failure, the waste sulfuric acid waste liquid in the acid-resistant heater 11 can flow to the backup reaction tank 22, and vice versa, thereby avoiding a complete shutdown of production due to overheating or failure.

[0042] In addition, having more than one backup production line can avoid complete shutdown of production due to overheating or failure, and can improve recycling capacity and efficiency.

[0043] Please refer to Figure 3, which is a flow chart of the method for recovering waste sulfuric acid waste liquid containing hydrogen peroxide according to the present invention.

[0044] like Figure 3 As shown, in step S100, the initial waste sulfuric acid waste liquid to be treated is pumped into the waste sulfuric acid preheating treatment tank 10 and is preheated to a preheating temperature of 50-60°C.

[0045] In step S110, the initial waste sulfuric acid waste liquid is directly heated by the acid-resistant heater 11, and the temperature of the initial waste sulfuric acid waste liquid in the acid-resistant heater 11 is raised to the target temperature of 70-80°C, and then injected into the reaction tank 12. In step S120, the waste sulfuric acid waste liquid recovery system 100 sets the processing time according to the temperature of the waste sulfuric acid waste liquid in the reaction tank 12 and the concentration of hydrogen peroxide, calculates the amount of reaction promoter added, and determines the addition mode of the reaction promoter according to the sulfuric acid concentration; the detection device 120 in the reaction tank 12 monitors whether the system temperature is higher than the safety value, and controls the waste sulfuric acid waste liquid solution to be transported to the first cooling heat exchanger 13. In step S130, a cooling cycle is performed to control the waste sulfuric acid waste liquid solution below 90°C. In step S140, the second cooling heat exchanger 14 outputs the recovery temperature to the sulfuric acid storage tank 15 close to room temperature or low temperature.

[0046] When the reaction process reaches equilibrium, the addition mode of the reaction accelerator is determined by the concentration of hydrogen peroxide: the first addition mode is to replenish the waste sulfuric acid waste liquid and add the reaction accelerator at the same time, and the second addition mode is to replenish the waste sulfuric acid waste liquid to the liquid level first, and then add the reaction accelerator for reaction.

[0047] The first addition mode simultaneously injects waste sulfuric acid liquid and adds a reaction accelerator, which has the advantage of accelerating the reaction time.

[0048] The second addition mode is to first inject the waste sulfuric acid and waste liquid, and then add the reaction promoter at one time to react. The advantage is that the dosage is better controlled.

[0049] The concentration of hydrogen peroxide in the reaction is inversely proportional to the reaction temperature, wherein the concentration of sulfuric acid in the reaction must be at least greater than 55%. The present invention can adjust the initial temperature of the reaction according to the initial temperature of the reaction tank 12, the sulfuric acid concentration of the waste sulfuric acid waste liquid, and the concentration of hydrogen peroxide, and control the maximum temperature of the treatment process below 100°C, and can reduce the concentration of hydrogen peroxide to 1%, thereby ensuring the recovery quality, treatment efficiency, recovery rate, and avoiding excessive temperature.

[0050] The recovery time and temperature rise required for the waste sulfuric acid waste liquid recovery system of the present invention will be determined by comparing different reaction promoters. The comparative example uses hydrochloric acid as the reaction promoter, while the example uses nitric acid as the reaction promoter.

[0051] Comparative Example 1: Efficiency of using hydrochloric acid to recover waste sulfuric acid waste liquid

[0052] Table 1

[0053]

[0054] As shown in Table 1, when the system reaction process is near the end, the concentration of hydrogen peroxide and the concentration of the reaction promoter in the system are both at a low level, and the final temperature of the waste sulfuric acid waste liquid is the main factor affecting the reaction time. In this comparative example, when the initial concentration of hydrogen peroxide in the waste sulfuric acid waste liquid is 3wt.%, the final temperature of the waste sulfuric acid waste liquid does not reach 75°C, and when the initial concentration of hydrogen peroxide in the waste sulfuric acid waste liquid is 5wt.%, the final temperature of the waste sulfuric acid waste liquid rises to a high temperature of 80-90°C, and the time required for the reaction to reach a hydrogen peroxide concentration of less than 30ppm is 20Hr, which is very inefficient.

[0055] Example 1: Temperature rise of decomposing hydrogen peroxide in waste sulfuric acid waste liquid

[0056] Table 2

[0057] Hydrogen peroxide decomposition concentration 1.0wt.% 2.0wt.% 3.0wt.% 4.0wt.% 5.0wt.% 6.0wt.% Minimum stacking temperature 90℃ 100℃ 110℃ 120℃ 130℃ 140℃ Maximum stacking temperature 93.7℃ 107.4℃ 121.1℃ 134.8℃ 148.5℃ 162.2℃

[0058] Table 2 shows the superposition of the temperature rise when 1.0wt.% of hydrogen peroxide is removed from the waste sulfuric acid waste liquid. According to the calculation of the heat of decomposition reaction of hydrogen peroxide, the temperature of the mixed solution of the waste sulfuric acid waste liquid and the reaction accelerator can rise by 13.7°C during the decomposition process of each 1wt.% of hydrogen peroxide. The actual value of the temperature rise will be affected by the environmental heat dissipation factor. The actual temperature rise is about 10-13.7°C. The main factors include weather, insulation method, and overall reaction time, which will affect the temperature change.

[0059] If the initial reaction temperature is 80°C and the initial concentration of hydrogen peroxide is 6.0%, it is estimated that under normal decomposition of hydrogen peroxide, the maximum temperature rise can be 82.2°C, and the final temperature of the system is 80+82.2=152.2°C. This high temperature will affect the service life of various equipment and components of the waste sulfuric acid and waste liquid recovery system. Therefore, the higher the hydrogen peroxide concentration, the lower the safety cooling cycle temperature control point needs to be, so that the sulfuric acid at which the final reaction is completed is <40°C.

[0060] In addition, for high-concentration waste sulfuric acid waste liquid (greater than 55wt.%), the reaction efficiency can be improved by intermittently adding a reaction promoter and stirring, but it is not applicable to low-concentration waste sulfuric acid waste liquid (less than 55wt.%). Therefore, it is recommended to increase the system sulfuric acid concentration to >55% for better reaction efficiency.

[0061] Example 2: Efficiency of using nitric acid to recover sulfuric acid waste liquid

[0062] Table 3

[0063]

[0064] As shown in Table 3, adding nitric acid to the hydrogen peroxide catalytic reaction will accelerate the overall reaction efficiency to 222 minutes (i.e., 3.9 hours) at the latest. In general, if the reaction promoter is changed to adding nitric acid, the recovery reaction can be accelerated to complete, the temperature rises quickly, and the starting temperature needs to be increased. The maximum temperature can reach about 113°C according to the test results. The rapid high-temperature reaction in a short time makes the temperature means more important.

[0065] The waste sulfuric acid waste liquid recovery system of the present invention can recover waste sulfuric acid waste liquid with sulfuric acid concentration between 35wt.% and 80wt.%, and the hydrogen peroxide concentration of the waste sulfuric acid waste liquid is usually below 10wt.%. The recovered sulfuric acid solution is an industrial-grade sulfuric acid solution, wherein the residual allowable amount of hydrogen peroxide is below 30ppm, and the residual allowable amount of nitric acid is between 200 and 400ppm.

[0066] In summary, the waste sulfuric acid waste liquid treatment system of the present invention recovers industrial-grade sulfuric acid solution within a certain period of time by setting the reaction setting time in the reaction tank. First, before the waste sulfuric acid waste liquid is injected into the reaction tank, it is determined whether to preheat and the preheating temperature according to the concentration of hydrogen peroxide, and an appropriate amount (minimum amount) of reaction accelerator is added, and the temperature after the reaction setting time (reaction end temperature) is estimated, and the cooling system is started to control the end temperature (i.e., the second cooling heat exchanger) to fall below 40°C, and then injected into the recovery tank to avoid harming the system.

[0067] The advantageous effects of the present invention are as follows: (1) the waste heat of the first cooling heat exchanger 13 is circulated to the initial waste sulfuric acid waste liquid by using a circulating heat exchange mode, and no additional hot water supply pump is needed as a heater, thereby reducing the heating cost; (2) two-stage cooling, the initial waste sulfuric acid waste liquid with a relatively low temperature is circulated to the first cooling heat exchanger 13 to reduce the cooling cost, and then the second cooling heat exchanger 14 is used to cool it to room temperature; (3) two addition modes are flexibly selected to improve the reaction efficiency; (4) two addition modes improve the controllability of the reaction temperature; (5) the reaction process is greatly accelerated, and the amount of sulfuric acid recovered is increased; (6) the generation of corrosive chlorine is reduced. In general, the reaction efficiency can be improved, the quality of sulfuric acid solution recovery can be improved, the temperature of the treatment process can be avoided to be too high, the heating and cooling costs can be reduced, and the effects of energy saving and carbon reduction can be avoided, and the safety concerns of overheating can be avoided.

Claims

1. A system for recovering waste sulfuric acid waste liquid containing hydrogen peroxide, characterized in that: Include: A preheating subsystem, comprising a waste sulfuric acid preheating treatment tank and an acid-resistant heater, wherein the waste sulfuric acid preheating treatment tank is connected to the acid-resistant heater; A reaction cycle control subsystem, comprising a reaction tank, the reaction tank being connected to the acid-resistant heater, and the reaction tank being used to receive a reaction accelerator; A cooling subsystem, comprising a first cooling heat exchanger and a second cooling heat exchanger, wherein one end of the first cooling heat exchanger is connected to the reaction tank, and the other end of the first cooling heat exchanger is connected to the second cooling heat exchanger; as well as a sulfuric acid storage tank connected to the second cooling heat exchanger; Among them, the initial waste sulfuric acid waste liquid is injected into the preheating subsystem from the waste sulfuric acid supply source, flows through the reaction cycle control subsystem, reacts with the reaction promoter to form a sulfuric acid solution, and then flows through the cooling subsystem for treatment to become a recovered sulfuric acid solution stored in the sulfuric acid storage tank.

2. The waste sulfuric acid waste liquid recovery system according to claim 1, characterized in that: The preheating waste sulfuric acid tank is used to preliminarily heat the injected initial waste sulfuric acid waste liquid to a preheating temperature of 50-60°C, and then flows into the acid-resistant heater, and the acid-resistant heater is used to heat to a target temperature of 70-80°C.

3. The waste sulfuric acid waste liquid recovery system according to claim 1, characterized in that: Further including: A first cold exchange pipeline is connected to the waste sulfuric acid supply source and extends through the first cooling heat exchanger and then connected to the preheat treatment waste sulfuric acid tank, so that the sulfuric acid solution in the first cooling heat exchanger is cooled by circulating the initial waste sulfuric acid waste liquid at room temperature in the first cold exchange pipeline.

4. The waste sulfuric acid waste liquid recovery system according to claim 1, characterized in that: Further including: The second cold exchange pipeline is connected to cooling water and extends outside the second cooling heat exchanger, so that the second cooling heat exchanger uses the cooling water to cool the sulfuric acid solution to be recovered to the recovery temperature to form the recovered sulfuric acid solution.

5. The waste sulfuric acid waste liquid recovery system according to claim 1, characterized in that: Further including: A heat exchange pipeline is connected to the first cooling heat exchanger and extends through the preheat treatment waste sulfuric acid tank and then connected to the second cooling heat exchanger, so that the initial waste sulfuric acid waste liquid in the preheat treatment waste sulfuric acid tank is heated by circulating the high-temperature sulfuric acid solution in the heat exchange pipeline.

6. The waste sulfuric acid waste liquid recovery system according to claim 1, characterized in that: Further including: A detection device is connected to the reaction tank, and is used to monitor the sulfuric acid concentration, hydrogen peroxide content, reaction temperature and nitrate compound content of the waste sulfuric acid waste liquid, and determine the addition amount and addition mode of the reaction accelerator.

7. The waste sulfuric acid waste liquid recovery system according to claim 6, characterized in that: The addition mode includes: a first mode and / or a second mode, wherein the first mode is to simultaneously inject the heated initial waste sulfuric acid waste liquid and the reaction accelerator into the reaction tank for reaction, and the second mode is to first inject the heated initial waste sulfuric acid waste liquid to the liquid level, and then add the reaction accelerator into the reaction tank for reaction.

8. The waste sulfuric acid waste liquid recovery system according to claim 7, characterized in that: The reaction accelerator is nitric acid.

9. The waste sulfuric acid waste liquid recovery system according to claim 1, characterized in that: The sulfuric acid concentration of the waste sulfuric acid waste liquid is greater than 55wt.%, and the hydrogen peroxide solution concentration of the waste sulfuric acid waste liquid is below 10wt.%.

10. The waste sulfuric acid waste liquid recovery system according to claim 1, characterized in that: The permissible residual amount of hydrogen peroxide in the sulfuric acid solution is 30 ppm or less, and the permissible residual amount of nitric acid is 200 to 400 ppm.

11. The waste sulfuric acid waste liquid recovery system according to claim 1, characterized in that: Further including: At least one backup waste sulfuric acid waste liquid recovery system, the backup waste sulfuric acid waste liquid recovery system includes: a backup preheating subsystem, a backup reaction cycle control subsystem and a backup cooling subsystem, which are used to circulate and cool the overheated sulfuric acid solution or serve as a backup system.

12. The waste sulfuric acid waste liquid recovery system according to claim 11, characterized in that: The backup preheating subsystem is connected to the reaction cycle control subsystem, and the preheating subsystem is connected to the backup reaction cycle control subsystem.

13. A method for recovering waste sulfuric acid waste liquid containing hydrogen peroxide, characterized in that: Include: Injecting the initial waste sulfuric acid waste liquid containing hydrogen peroxide from the waste sulfuric acid supply source into the preheating waste sulfuric acid tank of the preheating subsystem, heating the initial waste sulfuric acid waste liquid to the preheating temperature by circulating heat exchange, and then injecting the acid-resistant heater of the preheating subsystem to raise the temperature to the target temperature; Injecting the heated initial waste sulfuric acid waste liquid into the reaction tank in the reaction cycle control subsystem, and adding a reaction promoter to react to form a sulfuric acid solution; as well as The sulfuric acid solution is injected into the first cooling heat exchanger of the cooling subsystem, and the low-temperature initial waste sulfuric acid waste liquid is circulated for cooling, and the sulfuric acid solution to be recovered is cooled to the recovery temperature by cooling water through the second cooling heat exchanger to form a recovered sulfuric acid solution.

14. The method for recovering waste sulfuric acid and waste liquid according to claim 13, wherein: Further including: The waste sulfuric acid supply source is connected to the first cold exchange pipeline and extends through the first cooling heat exchanger and then connected to the preheat treatment waste sulfuric acid tank, so that the sulfuric acid solution in the first cooling heat exchanger is cooled by circulating the low-temperature initial waste sulfuric acid waste liquid in the first cold exchange pipeline.

15. The method for recovering waste sulfuric acid and waste liquid according to claim 13, characterized in that: Further including: The first cooling heat exchanger is connected to a heat exchange pipeline and extends through the preheat treatment waste sulfuric acid tank and then connected to the second cooling heat exchanger, so that the waste sulfuric acid liquid in the preheat treatment waste sulfuric acid tank is heated by circulating the high-temperature sulfuric acid solution in the heat exchange pipeline.

16. The method for recovering waste sulfuric acid and waste liquid according to claim 13, characterized in that: Further including: At least one backup waste sulfuric acid waste liquid recovery system is connected to the waste sulfuric acid supply source, the backup preheating subsystem of the backup waste sulfuric acid waste liquid recovery system is connected to the reaction cycle control subsystem, and the backup reaction cycle control subsystem of the backup waste sulfuric acid waste liquid recovery system is connected to the preheating subsystem, so that the overheated sulfuric acid solution can be circulated and cooled or used as a backup system.

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