Resource recycling system and process for waste sulfuric acid

Abstract

The invention relates to the technical field of waste sulfuric acid recovery, and particularly discloses a waste sulfuric acid resource recovery system and process, which comprises a separation and concentration treatment system, a methanol removal system and a waste gas treatment system, the separation and concentration treatment system comprises a dilute sulphuric acid cooler, a hydrogen peroxide storage tank, a desalted water feeding pipeline, a dilute sulphuric acid flash tank, a multi-stage sulphuric acid heater and a first-stage quench tower, the inlet end of the dilute sulphuric acid cooler is connected with a dilute sulphuric acid hydrolysis tank, and the outlet end of the dilute sulphuric acid cooler is connected with a dilute sulphuric acid intermediate tank; an outlet of the dilute sulphuric acid hydrolysis tank is connected with a methanol removal system through a pipeline, an inlet end of the hydrogen peroxide storage tank is connected with a desalted water feeding pipeline, an outlet end is connected with the dilute sulphuric acid intermediate tank through a pipeline, and a lower end outlet of the dilute sulphuric acid intermediate tank is connected with a waste siloxane collecting tank through a pipeline. According to the invention, methanol in waste sulfuric acid is pre-removed through the methanol removal system; the waste sulfuric acid is separated and concentrated through the separation and concentration treatment system, so that the concentration of the concentrated sulfuric acid reaches 96%.

Description

Technical Field

[0001] The invention belongs to the technical field of waste sulfuric acid recovery, and in particular relates to a waste sulfuric acid resource recovery system and process. Background Art

[0002] In the production process of organosilicon methyl chloride or methane chloride, concentrated sulfuric acid is needed to wash and purify the harmful substances in the methyl chloride gas, dichloromethane gas or chloroform gas: dimethyl ether, methanol, water vapor and silicon oxide, thereby producing dilute sulfuric acid containing organic matter as a by-product (the concentration of the waste sulfuric acid produced after drying is about 80wt%). Since the dilute sulfuric acid contains a large amount of organic matter, it cannot be recycled into the production system without treatment; However, during the reuse process, waste sulfuric acid has high viscosity and poor fluidity, which makes filtration difficult. If effective pretreatment is not carried out, it will affect subsequent processes and may clog pipelines. Secondly, the organic substances methyl chloride and methanol in dilute sulfuric acid are flammable and explosive substances. If they are not purified, there will be great safety hazards during storage, transportation and secondary utilization. Therefore, it is urgently necessary to invent and design a waste sulfuric acid resource recovery system and process to solve the above problems. Summary of the Invention

[0003] The purpose of the present invention is to provide a waste sulfuric acid resource recovery system, which solves the above-mentioned problem that waste sulfuric acid has high viscosity and poor fluidity, resulting in difficulty in filtration. If it is not effectively pretreated, it will affect subsequent processes and may clog pipelines. The organic substances methyl chloride and methanol in dilute sulfuric acid are both flammable and explosive substances. If they are not purified, they will pose a great safety hazard during storage, transportation and secondary utilization.

[0004] In order to solve the above technical problems, the present invention provides a waste sulfuric acid resource recovery system, including a separation and concentration treatment system, a methanol removal system and an exhaust gas treatment system, wherein the separation and concentration treatment system includes a dilute sulfuric acid cooler, a hydrogen peroxide storage tank, a desalted water feed pipeline, a dilute sulfuric acid flash tank, a multi-stage sulfuric acid heater and a primary quenching tower, the inlet end of the dilute sulfuric acid cooler is connected to a dilute sulfuric acid hydrolysis tank, and the outlet end is connected to a dilute sulfuric acid intermediate tank, the outlet of the dilute sulfuric acid hydrolysis tank is connected to the methanol removal system through a pipeline, the inlet end of the hydrogen peroxide storage tank is connected to the desalted water feed pipeline, and the outlet end is connected to the dilute sulfuric acid intermediate tank through a pipeline, and the dilute sulfuric acid intermediate tank is connected to the dilute sulfuric acid intermediate tank. The lower end outlet is connected to the waste siloxane collection tank through a pipeline, and the one side outlet is connected to the organic separation tower through a pipeline. The inlet end of the organic separation tower is connected to a gas pipeline, and the bottom outlet end is connected to the dilute sulfuric acid flash tank through a pipeline. The outlet end on the side wall is connected to two separation tower condensers arranged in series through a pipeline. The dilute sulfuric acid flash tank is connected in series with a multi-stage sulfuric acid heater through a pipeline. A sulfuric acid concentration tank is integrally formed on the sulfuric acid heater of each stage. Each sulfuric acid concentration tank is respectively connected to a dilute sulfuric acid washing tower and the first-level quenching tower through a pipeline. The dilute sulfuric acid washing tower and the first-level quenching tower are respectively connected to the exhaust gas treatment system through a pipeline.

[0005] Furthermore, the methanol removal system includes a methanol tower reboiler, a first-level methanol condenser of a methanol distillation tower, a second-level methanol condenser and a methanol collecting tank. The inlet end of the methanol tower reboiler is connected to a saturated steam pipeline, and the outlet end is connected to the methanol distillation tower. The top of the methanol distillation tower is connected to a nitrogen inlet pipeline, and the bottom is connected to a wastewater cooler. The inlet end of the first-level methanol condenser is connected to the methanol distillation tower through a pipeline, and the outlet end is connected to the second-level methanol condenser through a pipeline. The first-level methanol condenser and the second-level methanol condenser are respectively connected to the methanol collecting tank through pipelines, and the second-level methanol condenser is connected to the multi-stage sulfuric acid heater through pipelines.

[0006] Furthermore, the exhaust gas treatment system includes a primary exhaust gas cooler, a wastewater circulation tank, a wastewater collecting tank, a secondary exhaust gas cooler and a steam jet vacuum pump. The inlet end of the primary exhaust gas cooler is connected to the primary quenching tower, the lower outlet end is connected to the wastewater circulation tank, the top outlet end is connected to a water ring vacuum pump unit, the inlet end of the water ring vacuum pump unit is connected to an alkali solution metering tank, the wastewater circulation tank is connected to the wastewater collecting tank, the inlet end of the secondary exhaust gas cooler is connected to the dilute sulfuric acid washing tower through a pipeline, the outlet end is connected to the steam jet vacuum pump through a pipeline, and the steam jet vacuum pump is connected to the wastewater collecting tank.

[0007] Further, the outlet of the sulfuric acid concentration tank is connected with a concentrated sulfuric acid circulating tank, the concentrated sulfuric acid circulating tank is connected with a concentrated sulfuric acid cooler, and the outlet end of the concentrated sulfuric acid cooler is connected with a concentrated sulfuric acid oxidation system.

[0008] Further, a plurality of partitions are arranged in each of the sulfuric acid concentration tanks, and the partitions divide the inner cavity of the sulfuric acid concentration tank into a plurality of concentration chambers, and the last concentration chamber is communicated with the dilute sulfuric acid washing tower.

[0009] Further, the dilute sulfuric acid cooler is connected with a first circulating water pipeline, the separation tower condenser is connected with a second circulating water pipeline, the first-stage tail gas cooler is connected with a third circulating water pipeline, the first-stage methanol condenser is connected with a fourth circulating water pipeline, the wastewater cooler is connected with a fifth circulating water pipeline, the steam-jet vacuum pump is connected with a sixth circulating water pipeline, and the concentrated sulfuric acid cooler is connected with a seventh circulating water pipeline.

[0010] A waste sulfuric acid resource recycling system is used to operate a waste sulfuric acid resource recycling process, and the specific steps of the recycling process are as follows: S1, saturated steam with a mass flow of 130 kg / h and a pressure of 0.3 MPa is transported into the methanol tower reboiler through a saturated steam pipeline, and waste sulfuric acid solution is introduced into the methanol tower reboiler to evaporate and remove water and part of the methanol in the waste sulfuric acid solution, and the evaporated solution is transported into the methanol rectification tower through a pipeline, before which nitrogen is transported into the methanol rectification tower from a nitrogen inlet pipeline, the methanol rectification tower rectifies the solution, the waste liquid rectified out of the methanol rectification tower is cooled in the wastewater cooler, and the wastewater solution containing sulfuric acid in the wastewater cooler is cooled and then transported into the wastewater tank through a pipeline; The rectified solution containing methanol is sequentially transported into the first-stage methanol condenser for condensation, the methanol liquid produced by the methanol condenser is transported into the methanol collection tank to collect the produced methanol liquid, and the waste water solution containing sulfuric acid produced by condensation is transported into the second-stage methanol condenser for condensation, the waste water solution containing sulfuric acid produced when the methanol is collected in the methanol collection tank is also mixed into the second-stage methanol condenser and condensed, and the condensed waste water solution containing sulfuric acid is transported into the sulfuric acid concentration tank of the multi-stage sulfuric acid heater for heating and concentration; S2, adding industrial water to the dilute sulfuric acid hydrolysis tank for hydrolysis, the wastewater solution after hydrolysis is transported to the dilute sulfuric acid cooler through a pipeline for cooling, and the cooled wastewater solution is then transported to the dilute sulfuric acid intermediate tank through a pipeline. Prior to this, desalted water, industrial water and hydrogen peroxide are introduced into the hydrogen peroxide storage tank through the desalted water feed pipeline, and the mixed hydrogen peroxide is transported to the dilute sulfuric acid intermediate tank to mix with the wastewater solution, and the free waste siloxanes on the mixed solution are transported to the waste siloxane collection tank through a pipeline, and transported out of the system from the waste siloxane collection tank; The solution produced by the mixed reaction enters the organic separation tower for separation treatment. At the same time, nitrogen is used as an inert protective gas and is transported to the organic separation tower through a gas pipeline. The solution flows downward in the packing layer in the organic separation tower by gravity and transfers heat and mass with the water vapor in the tower in the packing layer. The purified dilute sulfuric acid liquid in the organic separation tower flows by gravity into the dilute sulfuric acid flash tank for flash evaporation. The water vapor flashed out under vacuum is concentrated into the multi-stage sulfuric acid heater. The dilute sulfuric acid liquid flashed out flows by gravity into the corresponding concentrated sulfuric acid tank. The sulfuric acid concentration tank mixes the condensed sulfuric acid-containing wastewater in S1 with the dilute sulfuric acid solution obtained by flash distillation. Under vacuum conditions, the dilute sulfuric acid solution in multiple concentration chambers in the sulfuric acid concentration tank boils and evaporates at a lower temperature, and the concentration increases step by step. The partitions of each concentration chamber in the previous stage prevent the backflow of the dilute sulfuric acid solution to balance the temperature difference between the heating tubes and the acid solution in the multi-stage sulfuric acid heater. The dilute sulfuric acid solution flows out of the last concentration chamber and is transported to the sulfuric acid collection tank. The concentration of the concentrated sulfuric acid is measured and found to be 96%; S3. The water vapor evaporated from the primary sulfuric acid concentration tank enters the primary quenching tower for cooling and demisting, and then enters the primary tail gas cooler of the exhaust gas treatment system for condensation. The generated non-condensable gas enters the water ring vacuum pump unit, and the condensed wastewater containing dilute sulfuric acid enters the wastewater circulation tank and is then collected in the wastewater collection tank. The wastewater containing dilute sulfuric acid in the wastewater collection tank is sent to the outside of the boundary area for use; The water vapor and dilute sulfuric acid vapor evaporated from the primary sulfuric acid concentration tank enter the dilute sulfuric acid scrubber for washing. The water vapor after washing in the dilute sulfuric acid scrubber enters the secondary tail gas cooler for condensation. The non-condensable gas after cooling enters the steam jet vacuum pump. The condensed sulfuric acid-containing wastewater is collected in the wastewater collection tank. The sulfuric acid-containing wastewater in the wastewater collection tank is transported to the wastewater treatment station for centralized treatment through the wastewater circulation pump. The non-condensable gas in the tail gas is discharged through the steam jet vacuum pump and washed in the tail gas scrubber before being emptied. The water vapor and dilute sulfuric acid vapor evaporated from the rear-stage sulfuric acid concentration tank enter the dilute sulfuric acid washing tower for washing. The washed dilute sulfuric acid overflows the dilute sulfuric acid washing tower and enters the primary sulfuric acid concentration tank. The dilute sulfuric acid concentrated in the primary sulfuric acid concentration tank reaches a certain concentration and is returned to the system in the previous process for use.

[0011] The beneficial effects of the present application are as follows: the methanol in the waste sulfuric acid is removed in advance by the methanol removal system; the waste sulfuric acid is separated and concentrated by the separation and concentration treatment system, so as to separate siloxane in the waste sulfuric acid and concentrate the waste sulfuric acid, so that the concentration of the concentrated sulfuric acid reaches 96%; the methanol and siloxane in the waste sulfuric acid are treated by the two treatment forms, so as to solve the problem that the methanol and siloxane in the dilute sulfuric acid are flammable and explosive, and cause a large safety hazard during storage, transportation and secondary utilization; The recovery process adopts the way of heating evaporation, rectification and step-by-step condensation to treat the waste sulfuric acid, so as to collect the methanol gas generated by cooling, so as to avoid the safety hazard caused by high temperature, and the waste water solution after rectification of the methanol is transported to the dilute sulfuric acid hydrolysis tank to be hydrolyzed with industrial water, the waste siloxane in the mixed solution after hydrolysis is removed by cooling and oxidation-reduction reaction, the remaining mixed reaction solution after removal of the waste siloxane is subjected to heat mass transfer with the water vapor in the tower in the packing layer, the sulfuric acid after impurity removal is subjected to multi-stage heating and concentration, part of the tail gas generated by the concentrated sulfuric acid is subjected to quenching through a primary quenching tower, and then subjected to cooling through a primary tail gas cooler, and the other part of the tail gas generated by the concentrated sulfuric acid is mixed with the concentrated sulfuric acid in the concentrated sulfuric acid circulating tank, and then subjected to washing through a dilute sulfuric acid washing tower, and then subjected to cooling, and part of the cooled sulfuric acid is injected into the waste water collection tank through a steam jet vacuum pump, and at the same time, the sulfuric acid after twice cooling is mixed in the waste water circulating tank and then enters the waste water collection tank, so as to improve the purity of the sulfuric acid, so that the concentration of the recovered sulfuric acid reaches 96%, and at the same time, the tail gas generated by concentration, quenching and washing can be effectively treated. The tail gas generated after concentration, quenching and washing is treated by the tail gas washing treatment method, so as to effectively reduce the content of sulfuric acid in the finally evaporated waste water, which can reach 0.01 mg / L at the lowest, and at the same time, the tail gas emission index is also reduced, so that the tail gas can meet the international emission standard. BRIEF DESCRIPTION OF DRAWINGS

[0012] In order to more clearly illustrate the technical solutions of the present application, the drawings needed in the following embodiments or prior art description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creating labor.

[0013] Figure 1 is the overall schematic diagram of the waste sulfuric acid resource recovery system of the present application; In the figure: 1-separation and concentration treatment system, 2-methanol removal system, 3-waste gas treatment system, 5-water ring vacuum pump unit, 6-alkali solution metering tank, 20-fifth circulating water pipeline, 21-methanol tower reboiler, 22-methanol rectification tower, 23-first stage methanol condenser, 24-second stage methanol condenser, 25-methanol collection tank, 26-saturated steam pipeline, 27-nitrogen gas inlet pipeline, 28-waste water cooler, 29-fourth circulating water pipeline, 31-first stage tail gas cooler, 32-waste water circulating tank, 33-waste water collection tank, 34-second stage tail gas cooler, 35-steam jet vacuum pump, 36-third circulating water pipeline, 37-sixth circulating water pipeline, 111-dilute sulfuric acid cooler, 112-hydrogen peroxide storage tank, 113-desalted water feeding pipeline, 114-dilute sulfuric acid flash tank, 115-multistage sulfuric acid heater, 116-first stage quenching tower, 117-dilute sulfuric acid hydrolysis tank, 118-dilute sulfuric acid intermediate tank, 119-waste siloxane collection tank, 120-organic matter separation tower, 121-gas pipeline, 122-separation tower condenser, 123-sulfuric acid concentration tank, 124-dilute sulfuric acid washing tower, 125-concentrated sulfuric acid circulating tank, 126-concentrated sulfuric acid cooler, 127-first circulating water pipeline, 128-second circulating water pipeline, 132-seventh circulating water pipeline. DETAILED DESCRIPTION

[0014] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the specification of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0015] In a specific embodiment of the present application, as shown in Figure 1As shown, specifically disclosed is a waste sulfuric acid resource recycling system, comprising a separation and concentration treatment system 1, a methanol removal system 2 and a waste gas treatment system 3. The separation and concentration treatment system 1 comprises a dilute sulfuric acid cooler 111, a hydrogen peroxide storage tank 112, a desalted water feeding pipe 113, a dilute sulfuric acid flash tank 114, a multi-stage sulfuric acid heater 115 and a primary quench tower 116. The inlet end of the dilute sulfuric acid cooler 111 is connected with a dilute sulfuric acid hydrolysis tank 117, and the outlet end is connected with a dilute sulfuric acid intermediate tank 118. The outlet of the dilute sulfuric acid hydrolysis tank 117 is connected with the methanol removal system 2 through a pipe. The inlet end of the hydrogen peroxide storage tank 112 is connected with the desalted water feeding pipe 113, and the outlet end is connected with the dilute sulfuric acid intermediate tank 118 through a pipe. The lower end outlet of the dilute sulfuric acid intermediate tank 118 is connected with a waste silicone collection tank 119 through a pipe, and a side outlet is connected with an organic matter separation tower 120 through a pipe. The inlet end of the organic matter separation tower 120 is connected with a gas pipe 121, the bottom outlet end is communicated with the dilute sulfuric acid flash tank 114 through a pipe, and the outlet end on the side wall is connected with two separation tower condensers 122 arranged in series through a pipe. The dilute sulfuric acid flash tank 114 is connected with the multi-stage sulfuric acid heater 115 through a pipe in series. In this embodiment, the multi-stage sulfuric acid heater 115 is preferably two stages, and a sulfuric acid concentration tank 123 is integrally formed on each stage of the sulfuric acid heater 115. Each sulfuric acid concentration tank 123 is connected with a dilute sulfuric acid washing tower 124 and a primary quench tower 116 through a pipe respectively. The dilute sulfuric acid washing tower 124 and the primary quench tower 116 are connected with the waste gas treatment system 3 through pipes respectively.

[0016] The methanol removal system 2 comprises a methanol tower reboiler 21, a methanol rectification tower 22, a primary methanol condenser 23, a secondary methanol condenser 24 and a methanol collection tank 25. The inlet end of the methanol tower reboiler 21 is connected with a saturated steam pipe 26, and the outlet end is connected with the methanol rectification tower 22. The top of the methanol rectification tower 22 is connected with a nitrogen gas inlet pipe 27, and the bottom is connected with a waste water cooler 28. The inlet end of the primary methanol condenser 23 is connected with the methanol rectification tower 22 through a pipe, and the outlet end is connected with the secondary methanol condenser 24 through a pipe. The primary methanol condenser 23 and the secondary methanol condenser 24 are connected with the methanol collection tank 25 through pipes respectively. The secondary methanol condenser 24 is connected with the multi-stage sulfuric acid heater 115 through a pipe.

[0017] The exhaust gas treatment system 3 comprises a first-stage tail gas cooler 31, a waste water circulating tank 32, a waste water collecting tank 33, a second-stage tail gas cooler 34 and a steam jet vacuum pump 35. The inlet end of the first-stage tail gas cooler 31 is connected with the first-stage quench tower 116, the lower outlet end is connected with the waste water circulating tank 32, and the top outlet end is connected with the water ring vacuum pump set 5. The inlet end of the water ring vacuum pump set 5 is connected with the lye metering tank 6. The waste water circulating tank 32 is connected with the waste water collecting tank 33. The inlet end of the second-stage tail gas cooler 34 is connected with the dilute sulfuric acid washing tower 124 through a pipeline, and the outlet end is connected with the steam jet vacuum pump 35 through a pipeline. The steam jet vacuum pump 35 is connected with the waste water collecting tank 33.

[0018] The outlet of the sulfuric acid concentration tank 123 is connected with a concentrated sulfuric acid circulating tank 125. The concentrated sulfuric acid circulating tank 125 is connected with a concentrated sulfuric acid cooler 126. The outlet end of the concentrated sulfuric acid cooler 126 is connected with a concentrated sulfuric acid oxidation system.

[0019] A plurality of partitions are arranged in each sulfuric acid concentration tank 123. The plurality of partitions divide the inner cavity of the sulfuric acid concentration tank 123 into a plurality of concentration chambers. The last-stage concentration chamber is in communication with the dilute sulfuric acid washing tower 124.

[0020] The dilute sulfuric acid cooler 111 is connected with a first circulating water pipeline 127 for temperature reduction and stable treatment of the dilute sulfuric acid cooler 111. The separation tower condenser 122 is connected with a second circulating water pipeline 128 for temperature reduction and stable treatment of the separation tower condenser 122. The first-stage tail gas cooler 31 is connected with a third circulating water pipeline 36 for temperature reduction and stable treatment of the first-stage tail gas cooler 31. The first-stage methanol condenser 23 is connected with a fourth circulating water pipeline 29 for temperature reduction and stable treatment of the first-stage methanol condenser 23. The waste water cooler 28 is connected with a fifth circulating water pipeline 20 for temperature reduction and stable treatment of the waste water cooler 28. The steam jet vacuum pump 35 is connected with a sixth circulating water pipeline 37 for temperature reduction and stable treatment of the steam jet vacuum pump 35. The concentrated sulfuric acid cooler 126 is connected with a seventh circulating water pipeline 132 for temperature reduction and stable treatment of the concentrated sulfuric acid cooler 126.

[0021] The saturated steam with a mass flow of 130 kg / h and a pressure of 0.3 MPa is delivered to the methanol tower reboiler 21 through the saturated steam pipeline 26, and the waste sulfuric acid solution is introduced into the methanol tower reboiler 21 to evaporate and remove the water and part of the methanol in the waste sulfuric acid solution, and the evaporated solution is delivered to the methanol rectification tower 22 through the pipeline, before which the nitrogen gas is delivered to the methanol rectification tower 22 from the nitrogen gas inlet pipeline 27, and the methanol rectification tower 22 rectifies the solution, and the waste liquid is introduced into the waste water cooler 28 to cool the waste water solution containing sulfuric acid, and the waste water solution containing a small amount of sulfuric acid in the waste water cooler 28 is cooled and delivered to the waste water tank through the pipeline; The rectified solution containing methanol is sequentially delivered to the first-stage methanol condenser 23 to be condensed, the methanol liquid produced by the methanol condenser 23 is delivered to the methanol collection tank 25 to collect the produced methanol liquid, and the waste water solution containing sulfuric acid produced by the condensation is delivered to the second-stage methanol condenser 24 to be condensed, and the waste water solution containing sulfuric acid produced when the methanol is collected in the methanol collection tank 25 is also introduced into the second-stage methanol condenser 24 to be mixed and condensed, and the condensed waste water solution containing sulfuric acid is introduced into the sulfuric acid concentration tank 123 of the multi-stage sulfuric acid heater 115 to be heated and concentrated; Industrial water is added to the dilute sulfuric acid hydrolysis tank 117 to be hydrolyzed, and the hydrolyzed waste water solution is delivered to the dilute sulfuric acid cooler 111 through the pipeline to be cooled, and the cooled waste water solution is delivered to the dilute sulfuric acid intermediate tank 118 through the pipeline, before which the desalted water, industrial water and hydrogen peroxide are introduced into the hydrogen peroxide storage tank 112 through the desalted water feeding pipeline 113, and the mixed hydrogen peroxide is delivered to the dilute sulfuric acid intermediate tank 118 to be mixed with the waste water solution, and the waste siloxane separated from the mixed solution is delivered to the waste siloxane collection tank 119 through the pipeline and delivered out of the system from the waste siloxane collection tank 119; The above methanol in the waste sulfuric acid is pre-removed through the methanol removal system 2; the waste sulfuric acid is separated and concentrated through the separation and concentration treatment system 3 to separate the siloxane in the waste sulfuric acid and concentrate the waste sulfuric acid to make the concentration of the concentrated sulfuric acid reach 96%; the methanol and siloxane in the waste sulfuric acid are treated through the two treatment forms to solve the problem that the methanol and siloxane in the dilute sulfuric acid are flammable and explosive, which causes a large safety hazard during storage, transportation and secondary utilization.

[0022] The solution produced by the mixed reaction enters the organic separation tower 120 for separation treatment. At the same time, nitrogen is used as an inert protective gas and is transported to the organic separation tower 120 through the gas pipeline 121. The solution flows downward in the packing layer in the organic separation tower 120 by gravity and transfers heat and mass with the water vapor in the tower in the packing layer. The purified dilute sulfuric acid liquid in the organic separation tower 120 flows by gravity into the dilute sulfuric acid flash tank 114 for flash evaporation. The water vapor flashed out under vacuum is concentrated into the multi-stage sulfuric acid heater 115. The dilute sulfuric acid liquid flashed out flows by gravity into the The corresponding sulfuric acid concentration tank 123 is used. The sulfuric acid concentration tank 123 mixes the sulfuric acid-containing wastewater solution condensed in S1 with the dilute sulfuric acid solution obtained by flash distillation. Under vacuum conditions, the dilute sulfuric acid solution in the multiple concentration chambers of the sulfuric acid concentration tank 123 boils and evaporates at a relatively low temperature, and the concentration increases step by step. The partitions of each concentration chamber in the previous stage prevent the dilute sulfuric acid solution from flowing back, thereby balancing the temperature difference between the heating tubes and the acid solution in the multi-stage sulfuric acid heater 115. The dilute sulfuric acid solution flows out of the last concentration chamber and is transported to the sulfuric acid collection tank. The concentration of the concentrated sulfuric acid is measured and found to be 96%. The gas separated by the organic separation tower 120 is separated by two separation tower condensers 122 connected in series, and is collected for later use after separation and condensation; The water vapor evaporated from the primary sulfuric acid concentration tank 123 enters the primary quench tower 116 for cooling and demisting, and then enters the primary tail gas cooler 31 of the exhaust gas treatment system 3 for condensation. The generated non-condensable gas enters the water ring vacuum pump unit 5. The condensed wastewater containing dilute sulfuric acid enters the wastewater circulation tank 32 and is then collected in the wastewater collection tank 33. The wastewater containing dilute sulfuric acid in the wastewater collection tank 33 is sent to the outside of the boundary area for use. The water vapor and dilute sulfuric acid vapor evaporated from the primary sulfuric acid concentration tank 123 enter the dilute sulfuric acid scrubber 124 for washing. The water vapor after washing in the dilute sulfuric acid scrubber 124 enters the secondary tail gas cooler 34 for condensation. The cooled non-condensable gas enters the steam jet vacuum pump 35. The condensed sulfuric acid-containing wastewater is collected in the wastewater collection tank 33. The sulfuric acid-containing wastewater in the wastewater collection tank 33 is transported to the wastewater treatment station for centralized treatment via the wastewater circulation pump. The non-condensable gas in the tail gas is discharged via the steam jet vacuum pump 35 and then washed in the tail gas scrubber before being discharged. The water vapor and dilute sulfuric acid vapor evaporated from the post-stage sulfuric acid concentration tank 123 enter the dilute sulfuric acid washing tower 124 for washing. The washed dilute sulfuric acid overflows the dilute sulfuric acid washing tower 124 and enters the primary sulfuric acid concentration tank 123. The dilute sulfuric acid concentrated in the primary sulfuric acid concentration tank 123 reaches a certain concentration and is returned to the system of the previous process for use. The recovery process adopts heating evaporation, rectification and step-by-step condensation to treat the waste sulfuric acid, to cool and collect the generated methanol gas, to avoid the safety hazards caused by high temperature, and to transport the waste water solution after rectification of the methanol to the dilute sulfuric acid hydrolysis tank 117 to hydrolyze with industrial water, to cool and oxidize the waste water solution after hydrolysis, to remove the free waste siloxane in the mixed solution, to remove the waste siloxane in the mixed reaction solution in the packing layer and heat quality transfer with the water vapor in the tower, to multi-stage heat and concentrate the sulfuric acid after impurity removal, to cool the tail gas generated by the concentrated sulfuric acid through the first-stage quenching tower 116, to cool the tail gas after quenching through the first-stage tail gas cooler 31, to mix the other part of the tail gas generated by the concentrated sulfuric acid with the concentrated sulfuric acid in the concentrated sulfuric acid circulating tank 125, to wash through the dilute sulfuric acid washing tower 124, to cool, to spray part of the cooled tail gas through the steam jet vacuum pump 35 into the waste water collecting tank 33, and to mix the sulfuric acid after twice cooling into the waste water circulating tank 32 and then into the waste water collecting tank 33 to improve the purity of the sulfuric acid, so that the concentration of the recovered sulfuric acid reaches 96%, and the tail gas generated by concentration, quenching and washing can be effectively treated. The tail gas generated by concentration, quenching and washing is treated by the tail gas washing process, which effectively reduces the content of sulfuric acid in the finally evaporated waste water, and the lowest content can reach 0.01 mg / L, and also reduces the tail gas emission index, so that the tail gas can meet the international emission standard.

[0023] The above only discloses one preferred embodiment of the present application, and of course cannot limit the scope of the present application, so equivalent changes made according to the claims of the present application are still within the scope of the present application.

Claims

1. A waste sulfuric acid resource recovery system, characterized in that: The invention comprises a separation and concentration treatment system (1), a methanol removal system (2) and an exhaust gas treatment system (3). The separation and concentration treatment system (1) comprises a dilute sulfuric acid cooler (111), a hydrogen peroxide storage tank (112), a desalted water feed pipe (113), a dilute sulfuric acid flash tank (114), a multi-stage sulfuric acid heater (115) and a primary quenching tower (116). The inlet end of the dilute sulfuric acid cooler (111) is connected to a dilute sulfuric acid hydrolysis tank (117), and the outlet end is connected to a dilute sulfuric acid intermediate tank (118). The outlet of the dilute sulfuric acid hydrolysis tank (117) is connected to the methanol removal system (2) through a pipeline. The inlet end of the hydrogen peroxide storage tank (112) is connected to the desalted water feed pipe (113), and the outlet end is connected to the dilute sulfuric acid intermediate tank (118) through a pipeline. The lower outlet of the dilute sulfuric acid intermediate tank (118) is connected to the dilute sulfuric acid intermediate tank (118) through a pipeline. A waste siloxane collecting tank (119) is provided, and one side outlet is connected to an organic separation tower (120) through a pipeline. The inlet end of the organic separation tower (120) is connected to a gas pipeline (121), and the bottom outlet end is communicated with the dilute sulfuric acid flash tank (114) through a pipeline. The outlet end on the side wall is connected to two separation tower condensers (122) arranged in series through a pipeline. The dilute sulfuric acid flash tank (114) is connected in series with multiple stages of sulfuric acid heaters (115) through pipelines. A sulfuric acid concentration tank (123) is integrally formed on each stage of the sulfuric acid heater (115). Each sulfuric acid concentration tank (123) is respectively connected to a dilute sulfuric acid washing tower (124) and the first-stage quenching tower (116) through a pipeline. The dilute sulfuric acid washing tower (124) and the first-stage quenching tower (116) are respectively connected to the waste gas treatment system (3) through pipelines.

2. A waste sulfuric acid resource recovery system according to claim 1, characterized in that: The methanol removal system (2) comprises a methanol tower reboiler (21), a first-level methanol condenser (23) of a methanol distillation tower (22), a second-level methanol condenser (24) and a methanol collecting tank (25). The inlet end of the methanol tower reboiler (21) is connected to a saturated steam pipeline (26), and the outlet end is connected to the methanol distillation tower (22). The top of the methanol distillation tower (22) is connected to a nitrogen inlet pipeline (27), and the bottom is connected to a wastewater cooler (28). The inlet end of the first-level methanol condenser (23) is connected to the methanol distillation tower (22) through a pipeline, and the outlet end is connected to the second-level methanol condenser (24) through a pipeline. The first-level methanol condenser (23) and the second-level methanol condenser (24) are respectively connected to the methanol collecting tank (25) through pipelines. The second-level methanol condenser (24) is connected to the multi-stage sulfuric acid heater (115) through pipelines.

3. A waste sulfuric acid resource recovery system according to claim 1, characterized in that: The exhaust gas treatment system (3) comprises a primary exhaust gas cooler (31), a wastewater circulation tank (32), a wastewater collecting tank (33), a secondary exhaust gas cooler (34) and a steam jet vacuum pump (35). The inlet end of the primary exhaust gas cooler (31) is connected to the primary quenching tower (116), the lower outlet end is connected to the wastewater circulation tank (32), the top outlet end is connected to a water ring vacuum pump unit (5), the inlet end of the water ring vacuum pump unit (5) is connected to an alkali solution metering tank (6), the wastewater circulation tank (32) is connected to the wastewater collecting tank (33), the inlet end of the secondary exhaust gas cooler (34) is connected to the dilute sulfuric acid washing tower (124) through a pipeline, the outlet end is connected to the steam jet vacuum pump (35) through a pipeline, and the steam jet vacuum pump (35) is connected to the wastewater collecting tank (33).

4. A waste sulfuric acid resource recovery system according to claim 1, characterized in that: The outlet of the sulfuric acid concentration tank (123) is connected to a concentrated sulfuric acid circulation tank (125), the concentrated sulfuric acid circulation tank (125) is connected to a concentrated sulfuric acid cooler (126), and the outlet end of the concentrated sulfuric acid cooler (126) is connected to a concentrated sulfuric acid oxidation system.

5. A waste sulfuric acid resource recovery system according to claim 1, characterized in that: Each of the sulfuric acid concentration tanks (123) is provided with a plurality of partitions, and the plurality of partitions divide the inner cavity of the sulfuric acid concentration tank (123) into multiple stages of concentration chambers, and the last stage of the concentration chamber is connected to the dilute sulfuric acid washing tower (124).

6. A waste sulfuric acid resource recovery system according to claim 1, characterized in that: The dilute sulfuric acid cooler (111) is connected to a first circulating water pipeline (127), the separation tower condenser (122) is connected to a second circulating water pipeline (128), the first-stage tail gas cooler (31) is connected to a third circulating water pipeline (36), the first-stage methanol condenser (23) is connected to a fourth circulating water pipeline (29), the wastewater cooler (28) is connected to a fifth circulating water pipeline (20), the steam jet vacuum pump (35) is connected to a sixth circulating water pipeline (37), and the concentrated sulfuric acid cooler (126) is connected to a seventh circulating water pipeline (132).

7. A waste sulfuric acid resource recovery process is operated using a waste sulfuric acid resource recovery system according to any one of claims 1 to 6, characterized in that: The specific steps of the recovery process are as follows: S1. Saturated steam with a mass flow rate of 130 kg / h and a pressure of 0.3 MPa is transported to the methanol tower reboiler (21) through the saturated steam pipeline (26), and waste sulfuric acid solution is introduced into the methanol tower reboiler (21) for heating and evaporation to evaporate the water and part of the methanol in the waste sulfuric acid solution. The evaporated solution is transported to the methanol distillation tower (22) through a pipeline. Prior to this, nitrogen is transported from the nitrogen inlet pipeline (27) to the methanol distillation tower (22). The methanol distillation tower (22) distills the solution, and the distilled waste liquid enters the waste water cooler (28) to cool the waste water solution containing sulfuric acid. The waste water solution containing trace amounts of sulfuric acid in the waste water cooler (28) is cooled and transported to the waste water tank through a pipeline. The methanol-containing solution distilled out is sequentially conveyed to the primary methanol condenser (23) for condensation. The methanol liquid generated by the condensation in the methanol condenser (23) is conveyed to the methanol collecting tank (25) to collect the generated methanol liquid. The sulfuric acid-containing wastewater solution generated by the condensation is conveyed to the secondary methanol condenser (24) for condensation. The sulfuric acid-containing wastewater solution generated when the methanol collecting tank (25) collects the methanol also enters the secondary methanol condenser (24) for mixing and condensation. The condensed sulfuric acid-containing wastewater solution enters the sulfuric acid concentration tank (123) of the multi-stage sulfuric acid heater (115) for heating and concentration. S2, industrial water is added to the dilute sulfuric acid hydrolysis tank (117) for hydrolysis, and the wastewater solution after hydrolysis is transported to the dilute sulfuric acid cooler (111) through a pipeline for cooling. The cooled wastewater solution is then transported to the dilute sulfuric acid intermediate tank (118) through a pipeline. Prior to this, desalted water, industrial water and hydrogen peroxide are introduced into the hydrogen peroxide storage tank (112) through the desalted water feeding pipeline (113), and the mixed hydrogen peroxide is transported to the dilute sulfuric acid intermediate tank (118) to mix with the wastewater solution. The free waste siloxane in the mixed solution is transported to the waste siloxane collecting tank (119) through a pipeline, and is transported out of the system from the waste siloxane collecting tank (119); The solution produced by the mixed reaction enters the organic separation tower (120) for separation treatment. At the same time, nitrogen is used as an inert protective gas and is transported to the organic separation tower (120) through a gas pipeline (121). The solution flows downward in the packing layer in the organic separation tower (120) by gravity and transfers heat and mass with the water vapor in the tower in the packing layer. The purified dilute sulfuric acid solution in the organic separation tower (120) flows by gravity into the dilute sulfuric acid flash tank (114) for flash evaporation. The water vapor flashed under vacuum is concentrated into the multi-stage sulfuric acid heater (115). The flashed dilute sulfuric acid solution flows by gravity under the action of gravity. Entering the corresponding sulfuric acid concentration tank (123), the sulfuric acid concentration tank (123) mixes the sulfuric acid-containing wastewater solution condensed in S1 with the dilute sulfuric acid solution flashed out, and under vacuum conditions, the dilute sulfuric acid solution in multiple concentration chambers in the sulfuric acid concentration tank (123) boils and evaporates at a lower temperature, and the concentration increases step by step. The partition of each concentration chamber of the previous stage prevents the backflow of the dilute sulfuric acid solution to balance the temperature difference between the heating tube and the acid solution in the multi-stage sulfuric acid heater (115). The dilute sulfuric acid solution flows out of the last concentration chamber and is transported to the sulfuric acid collection tank. The concentration of the concentrated sulfuric acid is measured, and the measured concentration is 96%; S3, the water vapor evaporated from the primary sulfuric acid concentration tank (123) enters the primary quenching tower (116) for cooling and demisting, and then enters the primary tail gas cooler (31) of the waste gas treatment system (3) for condensation. The generated non-condensable gas enters the water ring vacuum pump unit (5), and the condensed wastewater containing dilute sulfuric acid enters the wastewater circulation tank (32) and is then collected in the wastewater collection tank (33). The wastewater containing dilute sulfuric acid in the wastewater collection tank (33) is sent to the outside of the boundary area for use; The water vapor and dilute sulfuric acid vapor evaporated from the primary sulfuric acid concentration tank (123) enter the dilute sulfuric acid washing tower (124) for washing treatment. The water vapor washed by the dilute sulfuric acid washing tower (124) enters the secondary tail gas cooler (34) for condensation. The non-condensable gas after cooling enters the steam jet vacuum pump (35). The condensed sulfuric acid-containing wastewater is collected in the wastewater collection tank (33). The sulfuric acid-containing wastewater in the wastewater collection tank (33) is transported to the wastewater treatment station for centralized treatment via the wastewater circulation pump. The non-condensable gas in the tail gas is discharged via the steam jet vacuum pump (35) and then emptied after washing in the tail gas washing tower. The water vapor and dilute sulfuric acid vapor evaporated from the rear sulfuric acid concentration tank (123) enter the dilute sulfuric acid washing tower (124) for washing. The washed dilute sulfuric acid overflows the dilute sulfuric acid washing tower (124) and enters the primary sulfuric acid concentration tank (123). The dilute sulfuric acid concentrated in the primary sulfuric acid concentration tank (123) reaches a certain concentration and is returned to the system of the previous process for use.

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