A new method for efficiently regenerating waste acid and using the regenerated acid

Abstract

The invention discloses a highly efficient waste acid regeneration and utilization device and a new method for using regenerated acid, comprising a reactor, an acid-resistant and temperature-resistant pump, an inlet of which is connected to a waste acid storage tank, an outlet of which is connected to the reactor, an inlet of an acid-resistant and temperature-resistant pump, which is connected to the bottom of the reactor through a liquid outlet pipe, an outlet of the pump, which is connected to a liquid inlet of a gas-liquid mixer, a gas-liquid mixer or a gas-liquid mixer, or a plurality of mixers, an outlet of the gas-liquid mixer, a gas-liquid mixer or a gas-liquid mixer, or a plurality of mixers, and the reactor, the gas-liquid mixer is connected to an acid activator storage tank, the gas-liquid mixer is connected to a catalyst tank, an air outlet pipe is connected to the upper end of the reactor, the air outlet pipe is connected to the gas-liquid mixer, the gas-liquid mixer or a gas-liquid mixer, or a plurality of mixers, an air outlet pipe at the top of the reactor is connected to the catalyst tank in parallel with a low-pressure port of the gas-liquid mixer, a liquid outlet pipe is connected to the bottom of the reactor, the acid-resistant and temperature-resistant pump is connected to the liquid outlet pipe, and the liquid outlet pipe is connected to the acid-resistant and temperature-resistant pump. The equipment can effectively oxidize ferrous ions in the solution without gas leakage, and oxygen is fully utilized. After the waste acid treated by the equipment is regenerated and part of the new acid is prepared, it can be recycled as pickling liquid.

Description

Technical Field

[0001] The invention relates to the technical field of waste acid regeneration, and in particular to a highly efficient waste acid regeneration equipment and a new method for using the regenerated acid. Background Art

[0002] There is a layer of rust on the metal surface, which must be removed during use. Usually, pickling is used to remove rust. The pickling solution is generally made of hydrochloric acid, sulfuric acid, nitric acid, and hydrofluoric acid in a certain proportion. The pickling solution can be a single acid or a mixed acid. For example, carbon steel pickling is mostly a single acid, hydrochloric acid or sulfuric acid; stainless steel pickling is a mixed acid pickling of nitric acid + hydrofluoric acid. When the metal ion concentration in the pickling solution is too high, it will inhibit the dissolution of metal oxides, which will affect the pickling speed and effect, resulting in low production efficiency, so it is discharged as waste acid and new acid is re-prepared for pickling.

[0003] The pickling process is the process of removing the oxide layer on the metal surface. The reaction principle of pickling is as follows (taking hydrochloric acid in the carbon steel pickling process as an example):

[0004] FeO + 2HCl ==== FeCl2 + H2O (main reaction), Fe + 2HCl ==== FeCl2 + H2 (side reaction), the ionic equation is: FeO + 2H + ====Fe 2+ +H2O (main reaction), Fe+2H + ====Fe 2+ +H2 (side reaction). In the side reaction stage, as the substrate is corroded, the oxide on the surface of the substrate naturally peels off and gradually dissolves in the pickling solution to form ferrous salts. When the concentration of ferrous salt is high, it will cause the chemical equilibrium to proceed to the left, affecting the elution of metal oxides, such as ferrous chloride in the hydrochloric acid system mentioned above. Under high acidity conditions, the side reaction is more intense, consuming a large amount of metal substrate and acid, and generating a large amount of ferrous chloride. Therefore, how to control the side reaction is an important factor in reducing pickling consumption. Waste acid is a highly corrosive hazardous waste with a large amount of production. Generally, 30-50kg of waste acid will be produced when one ton of carbon steel is treated. A large amount of high-salt wastewater will be produced by neutralization treatment, which is difficult and has high treatment costs. Summary of the invention

[0005] The purpose of the present invention is to provide a highly efficient waste acid regeneration equipment and a new method for using regenerated acid. The equipment can activate and shield the ferrous ions in the pickling solution, greatly reduce the concentration of ferrous ions in the waste acid solution, so that the chemical reaction is conducive to the right. The trivalent iron ions in the activated acid can replace part of the acid solution. In particular, the trivalent iron has a strong corrosive effect on the substrate, and will not react with the iron substrate like acid to produce hydrogen bubbles. There is a layer of isolation film on the microscopic level to block the hydrogen ions from further corroding the substrate. Under the same acidity, its pickling speed is significantly faster than that of a single acid, and the pickling quality is better than that of a single acid. This technology has created a new pickling method, a method for pickling with a trivalent iron ion solution instead of an acid solution. Taking hydrochloric acid as an example, its chemical formula is: Fe+2FeCl3====3FeCl2 or the ionic formula is: Fe+2Fe 3+ ====3Fe 2+ , under normal circumstances, the concentration of ferrous ions reaches 100-150g / l, the pickling speed obviously decreases, the production efficiency obviously decreases, and the equipment capacity is reduced. At this time, the pickling solution can only be discharged as waste acid. If the waste acid is used to produce ferric chloride or ferrous chloride solid, the concentration is 20-30%, and further concentration treatment is required. Compared with the normal pickling process, the present invention uses the activated regeneration pickling solution, and the ferrous concentration in the waste acid solution will rise rapidly. When the ferrous ion concentration after enrichment reaches more than 200g / l, the discharged waste acid does not need to be evaporated, and there is no need to add solid ferrous salt or add iron filings to increase the ferrous content. The ferric chloride produced can reach 38-40% concentration. The product meets the requirements of "Water Treatment Agent Ferric Chloride" GB4482-2006, or the ferrous ions in the pickling solution are enriched to a saturated state, and the ferrous chloride product is produced by direct freezing and crystallization, so that the resource utilization of waste acid is achieved, and the energy-saving and emission-reduction effect is remarkable, and a large amount of equipment investment is saved, and the product production cost is greatly saved, and there is excellent economic benefit and good social and environmental benefits.

[0006] The above technical objectives of the present invention are achieved through the following technical solutions:

[0007] The invention discloses an efficient waste acid regeneration and utilization equipment and a new method for using regenerated acid, comprising a reactor, a mixing reactor, an acid activator storage tank, a catalyst tank, a waste acid storage tank and a regenerated acid storage tank, characterized in that the waste acid storage tank is connected with an acid-resistant and temperature-resistant pump 1, the acid-resistant and temperature-resistant pump 1 is connected to the reactor and serves as a waste acid feed pump, the acid-resistant and temperature-resistant pump 2 is used as a circulation pump or a discharge pump, and the waste acid circulation input of the reactor or the activated and regenerated regenerated acid discharge is realized by connecting the inlet and outlet liquid pipelines at the bottom of the reactor, the outlet of the acid-resistant and temperature-resistant pump 2 is connected to the liquid inlet of a gas-liquid mixer 1 or a gas-liquid mixer 2 or a plurality of mixers, the outlet of the gas-liquid mixer 1 or a gas-liquid mixer 2 or a plurality of mixers is connected to the reactor, the mixer is a venturi gas-liquid or liquid-liquid mixing reactor, the reactor has good atomization mixing effect and good reaction characteristics, the number of connections depends on the size of the reactor and the amount of waste acid regeneration per unit time, and the selected acid-resistant and temperature-resistant pump 2 should match the installed venturi gas-liquid reactor. The liquid outlet of the gas-liquid mixer reactor is connected to the reactor. The gas-liquid mixer 1, gas-liquid mixer 2, or multiple gas-liquid mixers are arranged on both sides of the reactor, two in a group, and one, two or more groups are selected according to the amount of waste acid to be treated. The acid activator storage tank, the catalyst tank and the unused acid activator (oxygen or chlorine) on the top of the reactor are respectively connected to the low-pressure suction port of the venturi gas-liquid mixing reactor, and the unreacted oxygen or chlorine is recycled until the reaction is completed. The upper end of the reactor is connected to an air outlet pipe, which is connected to gas-liquid mixer one and gas-liquid mixer two, and the air outlet pipe is connected to an activator tank or a catalyst tank. The bottom of the reactor is connected to a liquid outlet pipe, which is connected to acid-resistant and heat-resistant pump one or acid-resistant and heat-resistant pump two through a tee. The acid-resistant and heat-resistant pump one is connected to the liquid outlet pipe for pumping waste acid into the reactor, and the liquid outlet pipe is connected to the acid-resistant and heat-resistant pump two for activating a cyclic reaction of waste acid or pumping the activated regenerated acid into a regeneration acid tank. A tee is installed between the acid-resistant and heat-resistant pump two and the gas-liquid mixer two, and the other end of the tee is connected to the regeneration acid tank.

[0008] The reactor is the core component of the equipment, and its structure needs to be resistant to acid, alkali, temperature and pressure. In the field of carbon steel pickling, when the waste acid treated is mostly hydrochloric acid or sulfuric acid, steel-lined PTFE or enamel or fiberglass materials can be used. In the field of stainless steel pickling, nitric acid and hydrofluoric acid mixed acid are mostly used, and it is more appropriate to choose steel-lined PTFE materials for the reactor.

[0009] By adopting the above technical scheme, the waste acid storage tank is used to store the filtered waste acid, and the waste acid is transported to the reactor through the acid-resistant and temperature-resistant pump 1. The low-pressure port of the venturi gas-liquid mixing reactor connected to the acid-resistant and temperature-resistant pump 2 introduces the gas in the acid activator storage tank and the waste acid entering in the gas-liquid mixer 1 for mixed reaction, generating a large number of microbubbles, which enter the reactor together. The gas-liquid contact surface is large, which accelerates the reaction speed. After the reaction, the unconsumed gas comes out from the gas outlet pipe, and the liquid after the reaction comes out from the liquid outlet pipe. The acid-resistant and temperature-resistant pump 2 sucks the liquid in the reactor through the gas-liquid mixer again to circulate the unconsumed activator into the mixing reactor, and re-enters the reactor after mixing with the liquid. Under the closed circulation system, the gas in the acid activator storage tank will not overflow, and can circulate in the entire equipment all the time, and the activator is efficiently utilized in the circulation. After the reaction is complete, the acid-resistant and temperature-resistant pump 2 is used to pump the regenerated acid liquid into the regenerated acid tank. The inlet of the acid-resistant and temperature-resistant pump 2 is connected to the acid inlet and outlet pipes of the reactor, and the outlet is connected to the liquid inlet of the mixer or the acid discharge pipe through a tee, and the acid discharge pipe is connected to the regeneration acid tank. One or several groups of mixing reactors can be selected according to the size of the equipment. The outlets of the acid-resistant and temperature-resistant pump 1 or the acid-resistant and temperature-resistant pump 2 are both equipped with matching one-way valves to prevent the liquid in the reactor from flowing back.

[0010] Preferably, the gas-liquid mixer 1 and the gas-liquid mixer 2 are both Venturi reactors.

[0011] With the above technical solution, when gas or liquid flows in the Venturi reactor, the dynamic pressure reaches the maximum value and the static pressure reaches the minimum value at the narrowest part of the reactor, and the velocity of the gas (liquid) increases due to the reduction of the cross-sectional area of ​​the flow. The entire flow must undergo the process of pipeline contraction at the same time, so the pressure also decreases at the same time. Then a pressure difference is generated, which is used to measure or provide an external suction force to the fluid.

[0012] Preferably, the acid activator storage tank may contain oxygen or chlorine. From a safety perspective, we prefer oxygen as the acid activator, which is both safe, environmentally friendly and inexpensive. The catalyst tank contains a sodium nitrite aqueous solution, which may be prepared into a concentration of 5-20%.

[0013] By adopting the above technical solution, oxygen or chlorine can be used as an activator. When chlorine is used, there is no need to add sodium nitrite as a catalyst. When oxygen is used, sodium nitrite is added as a catalyst, which is beneficial to the conversion of ferric chloride.

[0014] Preferably, the outlets of the acid-resistant and temperature-resistant pump 1 and the acid-resistant and temperature-resistant pump 2 are both installed with one-way valve 1 or 2, and a one-way valve 3 is installed between the catalyst tank and the gas-liquid mixer 1.

[0015] By adopting the above technical solution, the one-way valve effectively prevents the solution in the reactor from flowing back.

[0016] Preferably, a pressure reducing valve and a flow valve are installed between the acid activator storage tank and the gas-liquid mixer.

[0017] By adopting the above technical solution, the pressure reducing valve controls the pressure at the outlet of the acid activator storage tank to be maintained within a certain range.

[0018] By adopting the above technical solution, the flow valve of the acid activator storage tank can monitor the oxygen consumption rate. When oxygen is no longer consumed or the consumption rate is very slow, the activation regeneration reaction ends, and the regenerated acid is transported to the regenerated acid storage tank through the acid-resistant and temperature-resistant pump 2.

[0019] Preferably, a safety valve is installed at the upper end of the reactor.

[0020] With the above technical solution, the safety valve is a special valve whose opening and closing parts are in a normally closed state under the action of external force. When the medium pressure in the reactor rises to exceed the set value, the medium (waste gas) is discharged to the outside of the system to prevent the medium pressure in the pipeline or equipment from exceeding the set value.

[0021] Preferably, the inner wall of the reactor is made of steel-lined polytetrafluoroethylene material, enamel material or fiberglass material, and a pressure sensor, a temperature sensor and a liquid level sensor are installed on the upper end.

[0022] By adopting the above technical scheme, the reaction conditions in the reactor are monitored by pressure sensors and temperature sensors to control the dosage and addition speed of the acid activator so that the acid activation speed is kept within the set range, and the liquid level in the reactor is measured by a liquid level sensor.

[0023] Preferably, the regenerated acid tank is connected to an acid-resistant pump for transporting the regenerated acid to the production line.

[0024] By adopting the above technical solution, a plurality of pneumatic valves and electric valves are installed on the equipment pipeline. By opening and closing the valves, the flow direction of liquid or gas is controlled to realize automatic operation of the equipment. The acid-resistant pump provides power to transport the solution in the regenerated acid tank to the production line.

[0025] Preferably, trivalent iron ions partially replace hydrogen ions and are used as a pickling agent in the metal surface treatment industry.

[0026] By adopting the above technical solution, iron can be washed and recycled, which greatly saves resources.

[0027] Preferably, the concentration of trivalent iron ions in the pickling solution may be between 10 g / l and 200 g / l, and the concentration of the acid may be above 10 g / l.

[0028] By adopting the above technical solution, the pickling reaction effect is better under the same acid solubility. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 A schematic structural diagram of an embodiment of the invention;

[0030] Figure 2 It is a structural schematic diagram of another embodiment of the invention.

[0031] Figure numerals: 1, reactor; 2, waste acid storage tank; 3, acid-resistant and temperature-resistant pump 1; 4, gas-liquid mixer 1; 5, acid activator storage tank; 6, gas-liquid mixer 2; 7, air outlet pipe; 8, catalyst tank; 9, liquid outlet pipe; 10, acid-resistant and temperature-resistant pump 2; 11, three-way pipe; 12, regenerated acid tank; 13, one-way valve 1; 14, one-way valve 2; 15, pressure reducing valve; 16, safety valve; 17, pressure sensor; 18, temperature sensor; 19, acid-resistant pump; 20, liquid level sensor; 21, one-way valve 3; 22, flow meter; 23, three-way pipe. DETAILED DESCRIPTION

[0032] The following is only a preferred embodiment of the present invention, and the protection scope is not limited to this embodiment. All technical solutions under the concept of the present invention should belong to the protection scope of the present invention. At the same time, it should be pointed out that for ordinary technicians in this technical field, some improvements and modifications without departing from the principle of the present invention should also be regarded as the protection scope of the present invention.

[0033] Embodiment 1:

[0034] like Figure 1 , an efficient waste acid regeneration and utilization equipment, including a reactor 1, the inner wall of the reactor 1 is made of steel-lined polytetrafluoroethylene material or enamel material or glass fiber reinforced plastic material, a gas-liquid mixer 1 4, a gas-liquid mixer 2 6, an acid activator storage tank 5, a catalyst tank 8, a waste acid storage tank 2 and a regenerated acid tank 12. The waste acid storage tank 2 is connected to an acid-resistant and temperature-resistant pump 1 3, which is connected to the bottom of the reactor through an inlet and outlet liquid pipe 9. The reactor 1 is connected to a gas-liquid mixer 1 4 and a gas-liquid mixer 2 6. The gas-liquid mixer 1 4 and the gas-liquid mixer 2 6 are both venturi reactors. When the gas or liquid flows in the venturi reactor, the dynamic pressure reaches the maximum value and the static pressure reaches the minimum value at the narrowest part of the reactor. The speed of the gas (liquid) increases because the cross-sectional area of ​​the flow is reduced. The entire surging flow must undergo a pipeline contraction process at the same time, so the pressure is also reduced at the same time, thereby generating a pressure difference. This pressure difference is used to measure or provide an external suction force to the fluid to suck in the unconsumed activator gas at the top of the reactor or the gas or catalyst liquid in the activator tank.

[0035] The gas-liquid mixer 4 is connected to an acid activator storage tank 5, a pressure reducing valve 15 and a flow meter 22 are installed between the acid activator storage tank 5 and the gas-liquid mixer 4, the acid activator storage tank 5 can be filled with oxygen or chlorine, and the catalyst tank 8 stores a sodium nitrite solution. Oxygen or chlorine can be used as an activator, and sodium nitrite is used as a catalyst, which is beneficial to the conversion of ferric chloride.

[0036] In the closed reactor 1, a circulating gas-liquid reactor is used to carry out a sufficient gas-liquid mixing reaction. This method uses a Venturi gas-liquid mixing reactor, and the reactants are waste acid, ferrous iron, oxygen or chlorine. Chlorine is more effective where conditions permit. Oxygen is more convenient and safer where conditions prohibit the use of chlorine. Oxygen or chlorine can also be used in combination. In the Venturi ejector, the liquid becomes small droplets, which increases the contact surface with the gas, thereby increasing the chemical reaction rate. The reaction mechanism is as follows (taking the hydrochloric acid system as an example):

[0037] 4FeCl2+4HCl+O2====4FeCl3+2H2O............⑴

[0038] 2FeCl2+Cl2====2FeCl3........................⑵

[0039] The ferrous chloride in the waste pickling solution is converted into ferric chloride, and the new pickling solution is prepared by using the activated regenerated acid, thereby eliminating the ferrous chloride that affects the pickling effect and changing the pickling equilibrium condition. This is a brand-new pickling method using the activated regenerated acid of the present invention.

[0040] The upper end of the reactor 1 is equipped with a safety valve 16, a pressure sensor 17 and a temperature sensor 18. The pressure sensor 17 and the temperature sensor 18 are used to measure the pressure and temperature changes in the reactor 1 to determine the degree of reaction and the amount of activator added. The safety valve 16 is an opening and closing member. The valve is opened or closed under the action of external force. It is in a normally closed state during the acid activation and regeneration process. The safety valve can be a pneumatic valve or an electric valve. It is opened or closed by the reaction process program control. When the medium pressure of the reactor 1 rises to more than the set value, the medium is discharged to the outside of the system to prevent the pipeline or equipment from being damaged. A special valve is provided for the medium pressure in the reactor 1 to exceed the set value. An air outlet pipe 7 is connected to the upper end of the reactor 1. The air outlet pipe 7 is connected to the gas-liquid mixer 1 4 and the gas-liquid mixer 2 6. The gas-liquid mixer 2 6 on one side of the air outlet pipe 7 is connected in parallel with the catalyst tank 8. A one-way valve 3 21 is installed between the mixer 2 6 and the catalyst tank 8. An inlet and outlet liquid pipe 9 is connected to the bottom of the reactor 1. An acid-resistant and temperature-resistant pump 1 3 is connected to the inlet and outlet liquid pipe 9 for pumping and inputting waste acid. The inlet and outlet liquid pipe 9 is also connected in parallel with an acid-resistant and temperature-resistant pump 2 10. The acid-resistant and temperature-resistant pump 2 10 is connected to the gas-liquid mixer 1 4 and the gas-liquid mixer 2 6. A three-way pipe 11 is installed between them, and the liquid enters the Venturi reactor from the inlet of the mixer 1 4 and the mixer 2 6 respectively, and the power source is provided by the acid-resistant and temperature-resistant pump 2. A one-way valve 2 14 is installed on the outlet pipeline. The one-way valve effectively prevents the solution in the reactor 1 from flowing back. The pump 2 10 pumps the activated regenerated acid into the regenerated acid tank 12 through the three-way pipe 23. A one-way valve 13 is installed between the acid-resistant and temperature-resistant pump 1 3 and the reactor 1 to prevent the liquid in the reactor 1 from flowing back to the waste acid tank. A liquid level sensor 20 is installed on the upper part of the reactor 1, and the liquid level sensor 20 is used to measure the liquid level of the reactor. The sensor adopts non-contact liquid level monitoring and transmits data to the control system at the same time. The control system controls the start and stop of the acid-resistant and temperature-resistant pump 3 and the opening and closing of various automatic valves in the pipeline to achieve the goal of automatic operation of the entire acid activation regeneration system. The new pickling solution is FeCl3 + 2HCl system, and the hydrochloric acid concentration can be lower. As long as FeCl3 is not hydrolyzed to precipitate Fe(OH)3, the pickling operation can be carried out. Under normal circumstances, the pH is below 1 (or the hydrochloric acid concentration is above 0.5%), and the pickling operation can be carried out effectively.

[0041] The reaction mechanism is as follows:

[0042] 2FeCl3+Fe====3FeCl2(main reaction)...............⑶

[0043] FeO+2HCl====FeCl2+H2O (side reaction)…⑷

[0044] Fe+2HCl====FeCl2+H2(side reaction)............⑸

[0045] From the redox potential, we can also see that the redox potential of ferric chloride and iron is higher than that of hydrochloric acid and iron, and its reaction speed is much faster than that of hydrochloric acid and iron. The results of our application to the pickling production line can greatly improve the working efficiency of the production line. Due to the erosion of trivalent iron on the iron substrate, the oxide layer of the pickling substrate can also be peeled off under low acidity conditions. If the skin is gone, the hair will not be attached. Therefore, under low acidity conditions, a large amount of ferrous oxide can be seen being peeled off. These ferrous oxides are well removed without consuming hydrochloric acid, achieving the pickling effect and greatly improving the utilization rate of the acid in the pickling solution. This is not available in existing pickling technology. This pickling method is a revolution in pickling technology, washing iron with iron and recycling it.

[0046] In the prior art, during the continuous pickling operation, the ferrous ion content in the pickling solution is required to be low. In the intermittent pickling method, in order to save acid and reduce the discharge of waste acid, the ferrous ion content in the pickling solution is relatively high. Generally, the ferrous ion concentration in the waste acid solution is 100-150g / l. If this waste acid is used to produce ferric chloride, solid ferrous chloride or concentrated ferrous chloride dilute solution or iron filings need to be added to react with hydrochloric acid to make the ferrous concentration reach more than 190g / l, so as to produce a product with a ferric chloride content of more than 38% (national standard). From the above reaction formula (3), we can see that each recycling cycle can produce 1.5 times more ferrous ions than the original pickling solution. After several recycling cycles, the ferrous ion content in the waste acid can reach more than 200g / l. The present invention controls the ferrous ion concentration or the total ferrous ion concentration to about 200g / l, and the national standard product of ferric chloride can be obtained. If solid ferrous chloride is required, even a supersaturated state of ferrous ions is reached. Without the need for concentration (or adding solid ferrous chloride), ferrous chloride or frozen crystallized ferrous chloride can be naturally crystallized.

[0047] The chemical reaction of this process is exothermic. As the reaction proceeds, the temperature of the acid activation regeneration system rises. In order to speed up the activation and regeneration, increasing the temperature is conducive to the formation of ferric chloride. The waste acid liquid can also be heated to 40°C and then oxygen or chlorine is introduced to increase the acid activation and regeneration rate. The reaction temperature can be controlled between room temperature and 100°C. When using chlorine as an activator, there is no need to heat the acid waste liquid.

[0048] When oxygen is used as an activator, in order to improve the activation and regeneration efficiency of the spent acid, adding a small amount of nitrite as a catalyst in equation (1) is beneficial to the conversion of ferric chloride.

[0049] NaNO2+FeCl2+2HCl====FeCl3+NO +NaCl+H2O.....⑹

[0050] NO+O2====NO2......................................⑺

[0051] 2FeCl2+NO2+2HCl====2FeCl3+NO +H2O............⑻

[0052] Equations ⑹ and ⑺ are both homogeneous reactions with faster reaction speeds. Equation ⑻ is a heterogeneous reaction. NO2 is mixed evenly in the Venturi reactor, and the amount of NO2 dissolved in the solution is increased, which has more contact opportunities with ferrous ions, thereby increasing the reaction speed. Finally, the oxidation of ferrous ions mainly consumes oxygen. Oxygen is excessive in the reaction system, and it is mixed with NOx and inhaled into the Venturi reactor. When the ferrous ions react completely and no longer consume oxygen, the activation regeneration reaction ends.

[0053] When using chlorine to oxidize ferrous chloride, in order to prevent environmental pollution and production safety caused by excessive chlorine, chlorine is used first to react without excess chlorine, and then oxygen is used to react to ensure that the ferrous ions are completely oxidized to meet the quality requirements of ferric chloride products, and there is no residual chlorine. When the acidity is low and the ferrous content is high, using chlorine as an activator has certain advantages, and no acid is consumed during the reaction. When producing ferric chloride products, the amount of chlorine or oxygen used is determined by measuring the ferrous ion content and acid content in the solution to ensure that the acid concentration in the product is within the product quality control range. For example, it is appropriate to react with chlorine within 80% in production. At this time, the temperature has risen to above 60°C, and then use excess oxygen to react completely, while consuming hydrochloric acid in the waste acid system.

[0054] The other end of the three-way pipe 23 is connected to the regeneration acid tank 12, and the activated regeneration acid is pumped to the regeneration acid tank 12 by the acid-resistant and temperature-resistant pump 2. The regeneration acid tank 12 is equipped with an acid-resistant pump 19 to pump the regeneration acid to the production line for acid preparation.

[0055] Embodiment 2: Figure 2 , Figure 1 and attached Figure 2 Two equipment structures are provided, and their principles are roughly the same, but they are slightly different in processing capacity. For equipment with a larger daily processing capacity, more than two groups of mixer structures can be selected. The principles are consistent and do not constitute the substantive content of the present invention. Therefore, the equipment of the present invention should include equipment with more than two groups of mixers.

[0056] According to the processing capacity of the equipment, one, two or more gas-liquid mixers can be installed on both sides of the reactor, and the design principles are the same.

[0057] It is beneficial to use more regenerated acid to prepare new pickling solution, which is conducive to the recycling of regenerated acid and saves the amount of new hydrochloric acid. It is also possible to directly use activated regenerated acid as pickling solution. Generally, 31% industrial hydrochloric acid: regenerated acid = 1:0.1-2.0 can achieve better pickling effect.

[0058] Example 3: Taking hydrochloric acid as an example, the pickling solution is prepared as follows: 31% industrial hydrochloric acid: regenerated acid = 1:0.1.

[0059] Example 4: Taking hydrochloric acid as an example, the pickling solution is prepared as follows: 31% industrial hydrochloric acid: regenerated acid = 1:0.5.

[0060] Example 5: Taking hydrochloric acid as an example, the pickling solution is prepared as follows: 31% industrial hydrochloric acid: regenerated acid = 1:1.

[0061] Example 6: Taking hydrochloric acid as an example, the pickling solution is prepared as follows: 31% industrial hydrochloric acid: regenerated acid = 1:1.5.

[0062] Example 7: Taking hydrochloric acid as an example, the pickling solution is prepared as follows: 31% industrial hydrochloric acid: regenerated acid = 1:2.

[0063] Example 8: Taking hydrochloric acid as an example, the pickling solution is prepared as follows: 31% industrial hydrochloric acid: regenerated acid = 1:5.

[0064] Example 9: Taking hydrochloric acid as an example, the pickling solution is prepared as follows: 31% industrial hydrochloric acid: regenerated acid = 1:10.

[0065] Example 10: Taking hydrochloric acid as an example, the pickling solution is prepared as follows: 31% industrial hydrochloric acid: regenerated acid = 0:1.

Claims

1. An efficient waste acid regeneration equipment, comprising a reaction kettle (1), a gas-liquid mixer 1 (4), a gas-liquid mixer 2 (6), an acid activator storage tank (5), a catalyst tank (8), a waste acid storage tank (2) and a regenerated acid tank (12), characterized in that: The invention also comprises an acid-resistant and temperature-resistant pump 1 (3) and an acid-resistant and temperature-resistant pump 2 (10), wherein the inlet of the acid-resistant and temperature-resistant pump 1 (3) is connected to the waste acid storage tank (2), and the outlet is connected to the reactor (1); the inlet of the acid-resistant and temperature-resistant pump 2 (10) is connected to the bottom of the reactor (1) through a liquid outlet pipe (9); the outlet of the pump is connected to the liquid inlet of the gas-liquid mixer 1 (4) or the gas-liquid mixer 2 (6) or a plurality of mixers; the outlet of the gas-liquid mixer 1 (4) or the gas-liquid mixer 2 (6) or a plurality of mixers is connected to the reactor (1); the gas-liquid mixer 1 (4) is connected to an acid activator storage tank (5); the gas-liquid mixer 2 (6) is connected to a catalyst tank (8); the reactor (1) is connected to the catalyst tank (9); The upper end of the reactor (1) is connected with an air outlet pipe (7), the air outlet pipe (7) is connected with a gas-liquid mixer (4) or a gas-liquid mixer (6) or a plurality of mixers, the air outlet pipe (7) and the catalyst tank (8) are connected in parallel to the low-pressure port of the gas-liquid mixer, the bottom of the reactor (1) is connected with a liquid outlet pipe (9), the acid-resistant and temperature-resistant pump (3) is connected with the liquid outlet pipe (9), and the liquid outlet pipe (9) is connected with an acid-resistant and temperature-resistant pump (10), the other end of the acid-resistant and temperature-resistant pump (10) is connected with a regeneration acid tank (12) through a three-way pipe (11), and the activated regeneration acid of the waste acid regeneration equipment contains a large amount of trivalent iron, and the acid washing liquid is prepared by using the trivalent iron.

2. The efficient waste acid regeneration and utilization equipment according to claim 1 is characterized in that: The gas-liquid mixer one (4) and the gas-liquid mixer two (6) or multiple mixers are all Venturi gas-liquid mixing reactors.

3. The efficient waste acid regeneration and utilization equipment according to claim 2 is characterized in that: The acid activator storage tank (5) contains oxygen or chlorine, and the catalyst tank (8) contains a sodium nitrite solution.

4. The efficient waste acid regeneration and utilization equipment according to claim 1 is characterized in that: A one-way valve (13) is installed between the acid-resistant and temperature-resistant pump (3) and the reactor (1), a one-way valve (14) is installed between the three-way pipe (11) and the gas-liquid mixer (4) or the gas-liquid mixer (6), and a one-way valve (21) is installed between the mixer (6) and the catalyst tank (8).

5. The efficient waste acid regeneration and utilization equipment according to claim 4 is characterized in that: A pressure reducing valve (15) and a flow sensor (22) are installed between the acid activator storage tank (5) and the gas-liquid mixer (4).

6. The efficient waste acid regeneration and utilization equipment according to claim 5, characterized in that: A safety valve (16) is installed at the upper end of the reaction kettle (1).

7. The efficient waste acid regeneration and utilization equipment according to claim 6 is characterized in that: The inner wall of the reaction kettle (1) is made of steel-lined polytetrafluoroethylene material, enamel material or glass fiber reinforced plastic material, and a pressure sensor (17), a temperature sensor (18) and a liquid level sensor (20) are installed on the upper end.

8. The efficient waste acid regeneration and utilization equipment according to claim 7 is characterized in that: The regenerated acid tank (12) is connected to an acid-resistant pump (19) for transporting the regenerated acid to the production line.

9. The efficient waste acid regeneration and utilization equipment according to claim 1, characterized in that: The trivalent iron ions partially replace the hydrogen ions and are used as pickling agents in the metal surface treatment industry.

10. The efficient waste acid regeneration and utilization equipment according to claim 9, characterized in that: The concentration of trivalent iron ions in the pickling solution is between 10g / L and 200g / L, and the concentration of acid is above 10g / L.

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