Recovery treatment method and recovery treatment equipment for waste sulfuric acid in pharmaceutical industry

Abstract

The invention discloses a recovery treatment method and recovery treatment equipment for waste sulfuric acid in the pharmaceutical industry, and the method comprises the following steps: (1) diluting the waste sulfuric acid in the pharmaceutical industry, and then filtering to obtain filtrate and a filter cake; (2) preheating the filtrate, and then carrying out atomization decomposition treatment to obtain decomposed gas; (3) carrying out catalytic combustion treatment on the decomposed gas to obtain combustion gas, and then carrying out dust removal treatment on the combustion gas to obtain dust-removed gas; (4) cooling the dedusted gas, then introducing the dedusted gas into a sulfuric acid absorption tower for absorption to obtain a sulfuric acid crude product, and introducing the residual gas which is not absorbed by the sulfuric acid absorption tower into a tail gas absorption tower for absorption; and (5) carrying out evaporation stripping treatment on the sulfuric acid crude product to obtain a liquid phase, namely a sulfuric acid product, and introducing a gas phase obtained by stripping into a tail gas absorption tower for absorption. The method is low in energy consumption, not only can remove organic matters in the waste acid and prepare qualified sulfuric acid products, but also is simple in process, easy to operate and convenient for industrial application.

Description

Technical Field

[0001] The invention relates to the technical field of waste acid treatment, and in particular to a recovery and treatment method and recovery and treatment equipment for waste sulfuric acid in the pharmaceutical industry. Background Art

[0002] In the pharmaceutical industry, concentrated sulfuric acid is often used as a reactant and catalyst for sulfonation, nitration and esterification reactions. As the reaction proceeds, the concentration of concentrated sulfuric acid gradually decreases and its performance gradually deteriorates. When the acidity drops to a certain level, it needs to be discharged. The discharged waste sulfuric acid is generally in the form of a black, viscous colloid, which contains a large amount of organic matter, including some high-molecular-weight alkanes, halogenated hydrocarbons and aromatic compounds, as well as a small amount of insoluble solid impurities, incompletely reacted nitric acid and water, etc. It has a pungent odor and will cause serious pollution to the environment if not properly disposed of.

[0003] At present, the processes for treating this type of waste sulfuric acid include extraction, neutralization, decolorization, etc. The extraction method uses an organic phase to extract organic matter from sulfuric acid, which requires a large amount of extractant and is costly. The neutralization method uses alkali solution and sulfuric acid for neutralization, but the sulfuric acid concentration of this type of waste acid is high, which requires a large amount of liquid alkali and generates sulfate containing organic matter. There is a lot of inferior waste, resulting in high disposal costs. Summary of the invention

[0004] The main purpose of the present invention is to provide a method and equipment for recovering waste sulfuric acid from the pharmaceutical industry, which has simple process, low energy consumption and can obtain sulfuric acid products with higher purity.

[0005] To achieve the above object, the present invention provides a method for recovering waste sulfuric acid in the pharmaceutical industry, comprising the following steps: (1) Dilute the waste sulfuric acid from the pharmaceutical industry and then filter it to obtain a filtrate and a filter cake; (2) preheating the filtrate and then performing atomization decomposition treatment to obtain decomposition gas; (3) subjecting the decomposed gas to catalytic combustion to obtain combustion gas, and then subjecting the combustion gas to dust removal to obtain dust-removed gas; (4) Cooling the dust-removed gas and then passing it into a sulfuric acid absorption tower for absorption to obtain crude sulfuric acid. The remaining gas not absorbed by the sulfuric acid absorption tower is passed into a tail gas absorption tower for absorption; (5) The crude sulfuric acid is subjected to evaporation and stripping treatment. The liquid phase obtained by stripping is the sulfuric acid product. The gas phase obtained by stripping is introduced into a tail gas absorption tower for absorption.

[0006] Furthermore, in step (1), the sulfuric acid content of the waste sulfuric acid from the pharmaceutical industry is 60 to 80 wt %, the COD value is 60 to 100 g / L, and the dilution multiple of the waste sulfuric acid from the pharmaceutical industry is 2 to 4 times.

[0007] Furthermore, in step (2), the preheating temperature is 30-80°C, and the temperature of the atomization decomposition treatment is 350-400°C.

[0008] Furthermore, in step (3), the catalyst for catalytic combustion treatment is Pt / Al2O3 or Pd / Al2O3, and the temperature is 400-500°C.

[0009] Furthermore, in step (4), the absorbent of the sulfuric acid absorption tower is waste sulfuric acid from pickling in the semiconductor industry with a sulfuric acid content of 40 to 60 wt% and a hydrogen peroxide content of 2 to 10 wt%.

[0010] Furthermore, in step (4), the absorbent of the tail gas absorption tower is a sodium hydroxide solution or a potassium hydroxide solution.

[0011] Furthermore, in step (5), the evaporation temperature is 120-160°C.

[0012] Furthermore, the heat of the dust-removed gas in step (4) is transferred to the filtrate in step (2) through a heat exchanger, thereby achieving cooling of the dust-removed gas and preheating of the filtrate.

[0013] The present invention also provides a recycling and processing equipment for implementing the above-mentioned recycling and processing method, including a raw material tank, a filter, a heat exchanger, an atomizer, a burner and a dust collector connected in sequence, and also including a cooler, a sulfuric acid absorption tower, a reboiler, a separator and a tail gas absorption tower connected in sequence, the filter and the atomizer are respectively connected to the two ends of the tube side of the heat exchanger, and the two ends of the shell side of the heat exchanger are respectively connected to the dust collector and the cooler.

[0014] Furthermore, the sulfuric acid absorption tower is also connected to the tail gas absorption tower, and a compressed air inlet is provided at the bottom of the separator.

[0015] Furthermore, the nozzle of the atomizer is made of ceramic material, and the dust collector is a cyclone dust collector, and the interior is made of 2205 material, which can resist high temperature corrosion.

[0016] The beneficial effects of the present invention are embodied in: After the waste sulfuric acid is diluted, the viscosity is reduced, which is convenient for filtering and removing organic solid impurities therein, reducing the pressure of the subsequent catalytic combustion stage, and the filtered solid impurities are treated as secondary waste. The filtrate is further atomized and decomposed. During the atomization and decomposition process, sulfuric acid is decomposed into SO3, SO2 and H2O, and acid-soluble organic matter is decomposed into short-chain high-molecular organic matter and a small amount of water and carbon dioxide, which is convenient for subsequent catalytic combustion and degradation; then the decomposed gas is catalytically combusted, and the organic matter generates carbon dioxide, water, hydrogen halide and small carbon-containing particles after catalytic combustion, and nitrogen in the air generates a small amount of nitrogen oxides during the combustion process. After dust removal and cooling, the obtained combustion gas enters a sulfuric acid absorption tower to absorb SO2 and SO3, and carbon dioxide, nitrogen oxides and hydrogen halide are absorbed to generate carbonic acid, nitric acid and hydrogen halide liquid. The obtained crude sulfuric acid uses the characteristics that the impurity acid (such as nitric acid, hydrogen halide, carbonic acid, etc.) has a different boiling point from sulfuric acid, and the impurity acid in the crude sulfuric acid is removed through an evaporation and stripping process, thereby obtaining a sulfuric acid product with higher purity.

[0017] Preheating the filtrate before atomization and decomposition can reduce energy consumption. Preheating the filtrate by exchanging heat between the dust removal gas and the filtrate can further reduce energy consumption.

[0018] The hydrogen peroxide in the waste sulfuric acid from pickling in the semiconductor industry is easy to decompose and produce bubbles. When its content is high, it will cause difficulties in its transportation and storage. Therefore, it is necessary to reduce its content. The absorption reaction is: SO2+H2O2--H2SO4, SO3+H2O--H2SO4. Using the waste sulfuric acid from pickling in the semiconductor industry as an absorbent can reuse the waste and reduce the content of hydrogen peroxide in the waste acid, which is convenient for storage and transportation.

[0019] The invention has low energy consumption, can not only remove organic matter in waste acid and prepare sulfuric acid product with high purity, but also has simple process, easy operation and convenient industrial application. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic structural diagram of a recycling and processing device according to an embodiment of the present invention.

[0021] Explanation of the accompanying drawings: 1. Raw material tank; 2. Filter; 3. Heat exchanger; 4. Atomizer; 5. Burner; 6. Dust collector; 7. Cooler; 8. Sulfuric acid absorption tower; 9. Reboiler; 10. Separator; 11. Tail gas absorption tower. DETAILED DESCRIPTION

[0022] The present invention is further described in detail below in conjunction with specific embodiments. Those of ordinary skill in the art will be able to implement the present invention based on these descriptions. In addition, the embodiments of the present invention involved in the following description are generally only embodiments of a part of the present invention, rather than all embodiments. Therefore, based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative work should fall within the scope of protection of the present invention.

[0023] Unless otherwise specified, the raw materials, reagents or devices used in the following examples can be obtained from conventional commercial sources or by existing known methods; unless otherwise specified, the methods used in the examples of the present invention are methods known to those skilled in the art. The catalysts Pt / Al2O3 and Pd / Al2O3 are existing catalysts in the art, formed by loading Pt or Pd on Al2O3 by impregnation, and the mass ratio of Pt or Pd to Al2O3 is 1:50.

[0024] See also Figure 1 The present invention is equipped with a set of recycling and processing equipment for implementing the recycling and processing method of waste sulfuric acid in the pharmaceutical industry of the present invention. The equipment includes a raw material tank 1, a filter 2, a heat exchanger 3, an atomizer 4, a burner 5 and a dust collector 6 connected in sequence, and also includes a cooler 7, a sulfuric acid absorption tower 8, a reboiler 9, a separator 10 and a tail gas absorption tower 11 connected in sequence. The filter 2 and the atomizer 4 are respectively connected to the two ends of the tube side of the heat exchanger 3, and the two ends of the shell side of the heat exchanger 3 are respectively connected to the dust collector 6 and the cooler 7. The sulfuric acid absorption tower 8 is also connected to the tail gas absorption tower 11. A compressed air inlet is provided at the bottom of the separator 10, and the dust collector 6 is a cyclone dust collector.

[0025] Example 1 Recovery and treatment of waste sulfuric acid in the pharmaceutical industry The steps are as follows: (1) 2 kg of waste sulfuric acid from the pharmaceutical industry containing 60 wt% sulfuric acid and a COD value of 60 g / L was put into a raw material tank 1, diluted by 2 times with water, and then passed through a filter 2 for filtration to obtain a filtrate and a filter cake; (2) The filtrate is passed through the heat exchanger 3 to be preheated to 30°C, and then passed through the atomizer 4 for atomization decomposition treatment. The atomizer temperature is 350°C, the atomizer atomizes instantly, and the residence time is about 5 seconds to obtain the decomposition gas; (3) The decomposed gas is passed into the burner 5 for catalytic combustion treatment, the catalyst is Pt / Al2O3, the catalytic combustion temperature is 400°C, the residence time is 10s, and combustion gas is obtained. The combustion gas is then passed into the dust collector 6 for dust removal treatment to obtain dust-removed gas; (4) The dust-removed gas passes through the heat exchanger 3 and then enters the cooler 7. After being cooled to 80°C, it is passed into the sulfuric acid absorption tower 8 for spraying and absorption with an absorbent to obtain a crude sulfuric acid product. The remaining gas not absorbed by the sulfuric acid absorption tower is passed into the tail gas absorption tower 11 for spraying and absorption with alkali solution; The absorbent of the sulfuric acid absorption tower is the semiconductor industry pickling waste sulfuric acid with a sulfuric acid content of 40wt% and a hydrogen peroxide content of 2wt%; the spray alkali solution of the tail gas absorption tower is a sodium hydroxide solution; (5) The crude sulfuric acid is introduced into a reboiler 9 and heated to 120°C, and then introduced into a separator 10 for stripping treatment. During stripping, compressed air is introduced from the compressed air inlet at the bottom. The liquid phase obtained by stripping is the sulfuric acid product. The gas phase obtained by stripping is introduced into a tail gas absorption tower 11 and sprayed with alkaline solution for absorption. The absorption liquid at the bottom of the tail gas absorption tower 11 is subsequently neutralized.

[0026] Example 2 Recovery and treatment of waste sulfuric acid in the pharmaceutical industry The steps are as follows: (1) 2 kg of waste sulfuric acid from the pharmaceutical industry containing 70 wt% sulfuric acid and a COD value of 80 g / L was put into a raw material tank 1, diluted 3 times with water, and then passed through a filter 2 for filtration to obtain a filtrate and a filter cake; (2) The filtrate is passed through the heat exchanger 3 to be preheated to 50°C, and then passed through the atomizer 4 for atomization decomposition treatment. The atomizer temperature is 380°C, the atomizer atomizes instantly, and the residence time is about 5 seconds to obtain the decomposition gas; (3) The decomposed gas is passed into the burner 5 for catalytic combustion treatment, the catalyst is Pt / Al2O3, the catalytic combustion temperature is 450°C, the residence time is 10s, and combustion gas is obtained. The combustion gas is then passed into the dust collector 6 for dust removal treatment to obtain dust-removed gas; (4) The dust-removed gas passes through the heat exchanger 3 and then enters the cooler 7. After being cooled to 80°C, it is passed into the sulfuric acid absorption tower 8 for spraying and absorption with an absorbent to obtain a crude sulfuric acid product. The remaining gas not absorbed by the sulfuric acid absorption tower is passed into the tail gas absorption tower 11 for spraying and absorption with alkali solution; The absorbent of the sulfuric acid absorption tower is the semiconductor industry pickling waste sulfuric acid with a sulfuric acid content of 50wt% and a hydrogen peroxide content of 6wt%; the spray alkali solution of the tail gas absorption tower is a sodium hydroxide solution or a potassium hydroxide solution; (5) The crude sulfuric acid is introduced into a reboiler 9 and heated to 140°C, and then introduced into a separator 10 for stripping treatment. During stripping, compressed air is introduced from the compressed air inlet at the bottom. The liquid phase obtained by stripping is the sulfuric acid product. The gas phase obtained by stripping is introduced into a tail gas absorption tower 11 and sprayed with alkaline solution for absorption. The absorption liquid at the bottom of the tail gas absorption tower 11 is subsequently neutralized.

[0027] Example 3 Recovery and treatment of waste sulfuric acid in the pharmaceutical industry The steps are as follows: (1) 2 kg of waste sulfuric acid from the pharmaceutical industry containing 80 wt% sulfuric acid and a COD value of 100 g / L was put into a raw material tank 1, diluted 4 times with water, and then passed through a filter 2 for filtration to obtain a filtrate and a filter cake; (2) The filtrate is passed through the heat exchanger 3 to be preheated to 80°C, and then passed through the atomizer 4 for atomization decomposition treatment. The atomizer temperature is 400°C, the atomizer atomizes instantly, and the residence time is 5s to obtain the decomposition gas; (3) The decomposed gas is introduced into the burner 5 for catalytic combustion treatment, the catalyst is Pd / Al2O3, the catalytic combustion temperature is 500°C, the residence time is 10s, and combustion gas is obtained. The combustion gas is then introduced into the dust collector 6 for dust removal treatment to obtain dust-removed gas; (4) The dust-removed gas passes through the heat exchanger 3 and then enters the cooler 7. After being cooled to 80°C, it is passed into the sulfuric acid absorption tower 8 for spraying and absorption with an absorbent to obtain a crude sulfuric acid product. The remaining gas not absorbed by the sulfuric acid absorption tower is passed into the tail gas absorption tower 11 for spraying and absorption with alkali solution; The absorbent of the sulfuric acid absorption tower is the semiconductor industry pickling waste sulfuric acid with a sulfuric acid content of 60wt% and a hydrogen peroxide content of 10wt%; the spray alkali solution of the tail gas absorption tower is a sodium hydroxide solution or a potassium hydroxide solution; (5) The crude sulfuric acid is introduced into a reboiler 9 and heated to 160°C, and then introduced into a separator 10 for stripping treatment. During stripping, compressed air is introduced from the compressed air inlet at the bottom. The liquid phase obtained by stripping is the sulfuric acid product. The gas phase obtained by stripping is introduced into a tail gas absorption tower 11 and sprayed with alkaline solution for absorption. The absorption liquid at the bottom of the tail gas absorption tower 11 is subsequently neutralized.

[0028] Comparative Example 1 In this comparative example, waste sulfuric acid from the pharmaceutical industry was treated in the same manner as in Example 1, except that the temperature of the atomizer was lowered to 330°C.

[0029] Comparative Example 2 In this comparative example, waste sulfuric acid from the pharmaceutical industry is treated in the same manner as in Example 1, except that the catalytic combustion temperature is lowered to 380°C.

[0030] Comparative Example 3 In this comparative example, waste sulfuric acid from the pharmaceutical industry is treated in the same manner as in Example 1, except that the heating temperature of the reboiler is reduced to 100°C.

[0031] The crude sulfuric acid and sulfuric acid products obtained in the above embodiments and comparative examples were tested for composition, and the results are shown in Table 1: Table 1 It can be seen that the low-temperature atomization effect is poor, resulting in the failure of partial sulfuric acid to be completely atomized, the sulfuric acid recovery rate is reduced, and the catalytic combustion temperature is reduced, resulting in the failure of partial organic matter to be completely burned, and the COD removal rate is low. The evaporation stripping temperature is reduced, resulting in the failure of partial hydrochloric acid and nitric acid to be completely stripped, and the removal effect is poor.

[0032] In addition, increasing the atomization temperature, catalytic combustion temperature, and evaporation temperature based on the process conditions of the present invention can only improve the atomization of sulfuric acid and the decomposition effect of organic matter to a limited extent, but will increase the energy consumption of the entire system.

[0033] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for recovering waste sulfuric acid in the pharmaceutical industry, characterized in that: The following steps are involved: (1) Dilute the waste sulfuric acid from the pharmaceutical industry and then filter it to obtain a filtrate and a filter cake; (2) preheating the filtrate and then performing atomization decomposition treatment to obtain decomposition gas; (3) subjecting the decomposed gas to catalytic combustion to obtain combustion gas, and then subjecting the combustion gas to dust removal to obtain dust-removed gas; (4) Cooling the dust-removed gas and then passing it into a sulfuric acid absorption tower for absorption to obtain crude sulfuric acid. The remaining gas not absorbed by the sulfuric acid absorption tower is passed into a tail gas absorption tower for absorption; (5) The crude sulfuric acid is subjected to evaporation and stripping treatment. The liquid phase obtained by stripping is the sulfuric acid product. The gas phase obtained by stripping is introduced into a tail gas absorption tower for absorption.

2. The method for recycling waste sulfuric acid in the pharmaceutical industry as claimed in claim 1, characterized in that: In step (1), the sulfuric acid content of the waste sulfuric acid from the pharmaceutical industry is 60 to 80 wt%, the COD value is 60 to 100 g / L, and the dilution multiple of the waste sulfuric acid from the pharmaceutical industry is 2 to 4 times.

3. The method for recycling waste sulfuric acid in the pharmaceutical industry according to claim 1 or 2, characterized in that: In step (2), the temperature is preheated to 30-80°C, and the temperature of the atomization decomposition treatment is 350-400°C.

4. The method for recycling waste sulfuric acid in the pharmaceutical industry according to claim 1 or 2, characterized in that: In step (3), the catalyst for catalytic combustion treatment is Pt / Al2O3 or Pd / Al2O3, and the temperature is 400-500°C.

5. The method for recycling waste sulfuric acid in the pharmaceutical industry according to claim 1 or 2, characterized in that: In step (4), the absorbent of the sulfuric acid absorption tower is waste sulfuric acid from pickling in the semiconductor industry with a sulfuric acid content of 40 to 60 wt% and a hydrogen peroxide content of 2 to 10 wt%.

6. The method for recycling waste sulfuric acid in the pharmaceutical industry according to claim 1 or 2, characterized in that: In step (4), the absorbent of the tail gas absorption tower is sodium hydroxide solution or potassium hydroxide solution.

7. The method for recycling waste sulfuric acid in the pharmaceutical industry according to claim 1 or 2, characterized in that: In step (5), the evaporation temperature is 120-160°C.

8. The method for recycling waste sulfuric acid in the pharmaceutical industry according to claim 1 or 2, characterized in that: The heat of the dust-removed gas in step (4) is transferred to the filtrate in step (2) through a heat exchanger, thereby cooling the dust-removed gas and preheating the filtrate.

9. A recycling equipment for implementing the recycling method according to any one of claims 1 to 8, characterized in that: It includes a raw material tank, a filter, a heat exchanger, an atomizer, a burner and a dust collector which are connected in sequence, and also includes a cooler, a sulfuric acid absorption tower, a reboiler, a separator and a tail gas absorption tower which are connected in sequence. The filter and the atomizer are respectively connected to the two ends of the tube side of the heat exchanger, and the two ends of the shell side of the heat exchanger are respectively connected to the dust collector and the cooler.

10. The recycling equipment according to claim 9, characterized in that: The sulfuric acid absorption tower is also connected to the tail gas absorption tower, and a compressed air inlet is provided at the bottom of the separator.

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