A kind of acetic anhydride production waste gas neutralization treatment equipment

Abstract

The invention discloses a neutralization treatment device for waste gas from acetic anhydride production, which belongs to the technical field of waste gas treatment and comprises a plurality of reaction tanks, a containing tank, a reflux component and a gas-liquid mixing component. The plurality of reaction tanks are connected to each other through a gas transmission pipe, and a spray pipe for spraying alkali solution is arranged inside the reaction tank, which is used to contact with waste gas and perform graded neutralization treatment on the waste gas. The plurality of containing tanks correspond to the plurality of reaction tanks one by one and are connected through a connecting pipe. The plurality of containing tanks are respectively used to contain alkali solutions of different concentrations, and the reflux component is used to re-transport the alkali solution in the containing tank to the spray pipe. The invention can react more fully with acidic components in the waste gas by passing the waste gas into alkali solutions of different concentrations in sequence, thereby improving the neutralization effect and reducing the content of acidic substances in the waste gas, and recycling the alkali solution after the neutralization reaction to save resources and reduce costs.

Description

Technical Field

[0001] The invention relates to the technical field of waste gas treatment, and in particular to a waste gas neutralization treatment device for acetic anhydride production. Background Art

[0002] Waste gas containing acetic acid, acetic anhydride and other organic compounds may be generated during the production of acetic anhydride. If these waste gases are directly discharged without treatment, they will pollute the air quality and the surrounding environment. The waste gas generated during the production of acetic anhydride usually needs to be treated with corresponding treatment measures to ensure the health and safety of workers and protect the environment. One method of waste gas treatment is to use alkaline solution for neutralization. This is because acetic acid is an acidic substance, and acetic anhydride also exhibits acidity in aqueous solution. The use of alkaline solution (such as sodium hydroxide or potassium hydroxide solution) can react chemically with these acidic substances to generate corresponding salts and water, thereby reducing harmful components in the waste gas.

[0003] During the production process, the concentration of the acetic anhydride waste gas may fluctuate due to the influence of factors such as the quality of raw materials, the control of reaction conditions, and the performance of equipment. At present, when the acetic anhydride waste gas is neutralized, the waste gas is generally passed into a washing tower to contact with alkali solution, wherein the concentration of the alkali solution is specific. As the neutralization reaction proceeds, the alkali solution will gradually be diluted and the concentration will decrease, thereby affecting its ability to absorb and neutralize acetic anhydride. If a specific concentration of alkali solution is used to treat all waste gases at one time, the concentration of some alkali solutions may be higher than the required neutralization capacity, resulting in a waste of alkali solution. Failure to effectively treat the acetic anhydride waste gas will result in excessive pollutant emissions, and as the neutralization reaction proceeds, the concentration of the alkali solution will change. If it is not adjusted in time, when the neutralization degree of the alkali solution reaches saturation, it may affect the neutralization effect of the waste gas. For this reason, we propose an acetic anhydride production waste gas neutralization treatment equipment to solve the above-mentioned problems. Summary of the invention

[0004] The embodiment of the present invention provides a neutralization treatment device for waste gas from acetic anhydride production to solve the above-mentioned technical problems.

[0005] The embodiment of the present invention adopts the following technical scheme: it includes multiple reaction tanks, storage tanks, reflux components and gas-liquid mixing components. The multiple reaction tanks are connected by an air supply pipe, and the interior of the reaction tank is provided with a spray pipe for spraying alkali solution, which is used to contact with the exhaust gas to perform graded neutralization treatment on the exhaust gas. The multiple storage tanks correspond to the multiple reaction tanks one by one and are connected by a connecting pipe. The multiple storage tanks are respectively used to hold alkali solutions of different concentrations. The reflux component is used to re-transport the alkali solution in the storage tank to the spray pipe. The gas-liquid mixing component is used to fully contact and mix the exhaust gas output by the air supply pipe with the alkali solution sprayed by the spray pipe.

[0006] Furthermore, the gas-liquid mixing component includes a spiral air outlet pipe, the spiral air outlet pipe is connected to the output end of the air supply pipe, and the spiral air outlet pipe is provided with a plurality of air outlets opening downward.

[0007] Furthermore, the gas-liquid mixing assembly includes a water supply ring connected to the output end of the spray pipe and a drainage column installed inside the reaction tank, and a plurality of water spray pipes are equidistantly arranged below the water supply ring, and the plurality of water spray pipes are equidistantly arranged around the axis of the drainage column.

[0008] Furthermore, the gas-liquid mixing assembly includes a spiral water spray pipe connected to the output end of the spray pipe, a plurality of spray heads are provided on the water spray pipe, and the output end direction of the gas supply pipe is tangent to the circumferential inner wall of the reaction tank.

[0009] Furthermore, the water spray pipe and the spray head are embedded in the interior of the reaction tank, and the output end of the spray head is flush with the inner wall of the reaction tank.

[0010] Furthermore, it also includes a liquid adding component, which is used to add alkali solution into the container so that the alkali solution reaches a set concentration. The liquid adding component includes a pH sensor and a controller arranged inside the container. The container is provided with a filling pipe for adding alkali solution into the container. The filling pipe is provided with a first water pump. The controller is used to control the opening and closing of the first water pump after receiving the detection signal of the pH sensor.

[0011] Furthermore, a pre-storage tank containing alkali solution of set concentration is provided below the containing tank, and the output end of the filling pipe extends into the pre-storage tank.

[0012] Furthermore, the reflux assembly includes a reflux pipe connected to the containing tank and a second water pump arranged on the reflux pipe, and the output end of the second water pump is connected to the input end of the spray pipe.

[0013] At least one of the above technical solutions adopted in the embodiments of the present invention can achieve the following beneficial effects:

[0014] 1: By first mixing the waste gas with the alkali solution with lower concentration and then passing it into the alkali solution with higher concentration in turn, when the waste gas contacts the alkali solution with lower concentration, most of the acetic acid and acetic anhydride are absorbed, which can reduce the energy consumption and treatment cost caused by excessive alkali concentration. After the initial absorption, the waste gas enters the alkali solution with higher concentration for remixing to further absorb the residual acetic acid and acetic anhydride. Finally, for those trace organic compounds that have not been completely absorbed in the first two stages, they will enter the subsequent reaction tank containing higher concentration alkali solution for deep reaction absorption, so that alkali solutions of different concentrations can react more fully with the acidic components in the waste gas, thereby improving the neutralization effect and reducing the content of acidic substances in the waste gas.

[0015] 2: A holding tank is provided under each level of the reaction tank to recycle the sprayed alkali solution and monitor the concentration of the alkali solution. When the concentration of the alkali solution gradually decreases below the set range as the reaction and neutralization work proceeds, the first water pump can be used to add alkali solution into the holding tank to increase the concentration of the alkali solution to reach the set threshold to avoid affecting the neutralization effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0017] Figure 1 An isometric structural schematic diagram provided by the present invention;

[0018] Figure 2 A schematic diagram of a cross-sectional structure provided by the present invention;

[0019] Figure 3 A schematic structural diagram of the first embodiment provided by the present invention;

[0020] Figure 4 A schematic diagram of a second embodiment of the present invention;

[0021] Figure 5 A schematic structural diagram of a third embodiment of the present invention;

[0022] Figure 6 This is a schematic diagram of the cross-sectional structure of a single reaction tank provided by the present invention.

[0023] Reference numerals:

[0024] 1. Reaction tank; 11. Air pipe; 2. Spray pipe; 3. Container; 31. Connecting pipe; 32. Air outlet; 4. Air outlet pipe; 41. Water supply ring; 42. Drainage column; 43. Water spray pipe; 45. Spray head; 5. pH sensor; 51. Controller; 52. Filling pipe; 53. First water pump; 6. Pre-storage tank; 7. Reflux pipe; 71. Second water pump. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the specific embodiments of the present invention and the corresponding drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0026] The technical solutions provided by various embodiments of the present invention are described in detail below in conjunction with the accompanying drawings.

[0027] The embodiment of the present invention provides a device for neutralizing and treating waste gas from acetic anhydride production, such as Figure 1-6 As shown, it includes a reaction tank 1 for mixing and neutralizing waste gas and alkali solution and a container 3 for containing the alkali solution after the reaction and neutralization in the reaction tank 1. The number of reaction tanks 1 and container 3 is multiple, and the reaction tanks 1 correspond to the container 3 one by one, and are connected through a connecting pipe 31. The interior of the reaction tank 1 is provided with a spray pipe 2 for spraying alkali solution. The preferred number of reaction tanks 1 is three, and the three reaction tanks 1 are connected through an air supply pipe 11. The air supply pipe 11 located on the input end reaction tank 1 can be connected to the external waste gas output pipe for conveying waste gas into the reaction tank 1. The reaction tank 1 located at the rear end can be provided with an exhaust pipe for discharging the gas that meets the standard after the neutralization reaction. The concentration of the alkali solution contained in the container 3 gradually increases from the input end to the output end of the air supply pipe 11 to form primary treatment, intermediate treatment and deep treatment. First, the waste gas After being mixed with the alkali solution of lower concentration in the first reaction tank 1, most of the acetic acid and acetic anhydride can be absorbed, reducing the energy consumption and treatment cost caused by excessive alkali concentration. The waste gas after preliminary absorption and neutralization enters the intermediate treatment reaction tank 1 through the gas pipeline 11. The concentration of alkali solution in this reaction tank 1 is relatively increased to further absorb the residual acetate rods and organic compounds such as esters and ketones. After that, the waste gas enters the ultimate neutralization treatment reaction tank 1 for deep treatment. The concentration of alkali solution in this reaction tank 1 is higher than that of the first two stages of reaction tanks 1, so that those trace organic compounds that have not been completely absorbed in the first two stages are deeply neutralized and absorbed, so that the content of harmful substances is reduced until it meets the emission standards. The alkali solution of different concentrations can react more fully with the acidic components in the waste gas, thereby improving the neutralization effect and reducing the content of acidic substances in the waste gas.

[0028] The alkali solution sprayed from the spray pipe 2 is flushed back into the container 3 through the connecting pipe 31 for recovery, and a reflux component is also provided between the container 3 and the reaction tank 1. The reflux component is used one by one with the container 3 to realize the reflux of alkali solutions of different concentrations. Figure 2 As shown, the reflux assembly includes a reflux pipe 7 connected to the containing tank 3 and a second water pump 71 arranged on the reflux pipe 7. The output end of the second water pump 71 is connected to the input end of the spray pipe 2. The alkali solution in the containing tank 3 is extracted by the second water pump 71 and input into the spray pipe 2 again, so that the alkali solution is re-sprayed into the corresponding reaction tank 1 to achieve reuse.

[0029] Among them, the exhaust gas entering the reaction tank 1 is fully contacted with the alkali solution sprayed by the spray pipe 2 through the gas-liquid mixing component to increase the contact opportunity between the alkali solution and the exhaust gas and improve the neutralization treatment efficiency. The following is a specific implementation method for achieving full gas-liquid mixing in the present invention;

[0030] like Figure 3 As shown, the first embodiment provided by the present invention is that the gas-liquid mixing component includes a spiral air outlet pipe 4, the spiral air outlet pipe 4 is connected to the output end of the air supply pipe 11, and a plurality of air outlets 32 are opened on the spiral air outlet pipe 4, and the exhaust gas is discharged through multiple points through the multiple air outlets 32, so that the exhaust gas is more evenly distributed in the reaction tank 1, so that the contact with the alkali solution sprayed from the spray pipe 2 is more uniform, and the air outlet 32 ​​opens downward to prevent the alkali solution sprayed from the spray pipe 2 from entering the air outlet pipe 4 through the air outlet 32.

[0031] like Figure 4 As shown, the second embodiment provided by the present invention is that the gas-liquid mixing component includes a water supply ring 41 connected to the output end of the spray pipe 2 and a drainage column 42 installed in the reaction tank 1, and a plurality of water spray pipes 43 are equidistantly arranged below the water supply ring 41, and the plurality of water spray pipes 43 are equidistantly arranged around the axis of the drainage column 42, and the output end of the gas pipe 11 is located directly below the drainage column 42. When the exhaust gas is output from the gas pipe 11, it first passes through the obstruction at the bottom end of the drainage column 42 and then diffuses to the surrounding side of the drainage column 42, so as to fully contact with the water spray pipes 43 equidistantly arranged around the circumference, so that when the exhaust gas is output, the center of the exhaust gas has less contact with the alkali solution, resulting in uneven mixing.

[0032] like Figure 5 As shown, the third embodiment provided by the present invention is that the gas-liquid mixing component includes a spiral water spray pipe 43 connected to the output end of the spray pipe 2, and a plurality of spray heads 45 are provided on the water spray pipe 43. The output end direction of the gas delivery pipe 11 is tangent to the circumferential inner wall of the reaction tank 1. When the gas delivery pipe 11 sprays the exhaust gas, the exhaust gas moves along the circumferential inner wall of the reaction tank 1, so that the gas generates a rotating airflow, which can enhance the flow efficiency of the gas and improve the gas transportation capacity, so as to fully mix with the alkali solution sprayed from the spiral water spray pipe 43, and can absorb and treat harmful substances in the exhaust gas to the maximum extent;

[0033] Among them, Figure 6As shown, the water spray pipe 43 and the spray head 45 are both embedded in the interior of the reaction tank 1, and the output end of the spray head 45 is flush with the inner wall of the reaction tank 1, so that the circumferential inner wall of the reaction tank 1 tends to be smooth, and the water spray pipe 43 and the spray head 45 are prevented from protruding from the inner wall of the reaction tank 1 to cause a large disturbance to the gas rotating in the reaction tank 1, resulting in the gas being unable to rotate. When the alkali solution is sprayed out through the spray head 45, the rotating gas can be properly disturbed to improve the dispersion effect of the gas. Different from the first and second embodiments, the movement path of the exhaust gas and the spray path of the alkali solution in the third embodiment are more dispersed, so that the contact area between the exhaust gas and the alkali solution will be larger and the mixing effect will be better. However, since the spray pipe 2 needs to be placed in the inner layer of the reaction tank 1, the manufacturing and maintenance costs are also relatively large.

[0034] Preferably, it also includes a liquid adding component, which is used to add alkali solution into the storage tank 3 to make the alkali solution reach a set concentration. As the neutralization reaction of the alkali solution and the exhaust gas continues, corresponding salts (such as sodium acetate) and water will be mainly produced. The approximate chemical equation is as follows: C4H6O3 (acetic anhydride) + NaOH (alkali solution) → C4H5NaO3 (sodium acetate) + H2O (water). The salt and water therein may dilute the concentration of the alkali solution, causing the concentration of the alkali solution to decrease, or because more exhaust gas is processed or the alkali solution has absorbed enough pollutants and cannot continue to be effectively neutralized. In order to maintain the neutralization effect, new alkali solution needs to be regularly replenished, and it is added to the storage tank 3 in time through the liquid adding component, such as Figure 2 As shown, the liquid adding component includes a pH sensor 5 and a controller 51 arranged inside the container 3. The container 3 is provided with a filling pipe 52 for adding alkali solution into the container 3. The filling pipe 52 is provided with a first water pump 53. The controller 51 is used to control the opening and closing of the first water pump 53 after receiving the detection signal of the pH sensor 5. When the pH sensor 5 detects that the concentration of the alkali solution in the corresponding container 3 is lower than the set value, the signal is transmitted to the controller 51. The controller 51 controls the corresponding first water pump 53 to start, so that the filling pipe 52 adds alkali solution into the container 3 to make it reach the set concentration threshold.

[0035] Preferably, a pre-storage tank 6 containing alkali solution of set concentration is provided below the containing tank 3 , and the output end of the filling pipe 52 extends into the pre-storage tank 6 for providing alkali solution of appropriate concentration into the containing tank 3 .

[0036] The above description is only an embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent substitution, improvement, etc. made within the spirit and principle of the present invention should be included in the scope of the claims of the present invention.

Claims

1. A neutralization treatment device for waste gas from acetic anhydride production, characterized in that: include; A plurality of reaction tanks (1), wherein the plurality of reaction tanks (1) are connected to each other via a gas transmission pipe (11), and a spray pipe (2) for spraying alkali solution is provided inside the reaction tank (1) for contacting with the waste gas to perform graded neutralization treatment on the waste gas; A containing tank (3), wherein the plurality of containing tanks (3) correspond one to one with the plurality of reaction tanks (1) and are connected via a connecting pipe (31), and the plurality of containing tanks (3) are respectively used to contain alkali solutions of different concentrations; A reflux component, the reflux component being used to transport the alkali solution in the container (3) back to the spray pipe (2); A gas-liquid mixing component, the gas-liquid mixing component is used to fully contact and mix the waste gas output by the gas transmission pipe (11) with the alkali liquid sprayed by the spray pipe (2); The gas-liquid mixing assembly comprises a spiral water spray pipe (43) connected to the output end of the spray pipe (2), a plurality of spray heads (45) are provided on the water spray pipe (43), and the output end direction of the gas delivery pipe (11) is tangent to the circumferential inner wall of the reaction tank (1); The water spray pipe (43) and the spray head (45) are both embedded in the interior of the reaction tank (1), and the output end of the spray head (45) is flush with the inner wall of the reaction tank (1).

2. The acetic anhydride production waste gas neutralization treatment equipment according to claim 1, characterized in that: The invention also comprises a liquid adding component, the liquid adding component is used to add alkali solution into the container (3) so that the alkali solution reaches a set concentration, the liquid adding component comprises a pH sensor (5) and a controller (51) arranged inside the container (3), the container (3) is provided with a filling pipe (52) for adding alkali solution into the container (3), the filling pipe (52) is provided with a first water pump (53), and the controller (51) is used to control the opening and closing of the first water pump (53) after receiving a detection signal from the pH sensor (5).

3. The acetic anhydride production waste gas neutralization treatment equipment according to claim 2, characterized in that: A pre-storage tank (6) containing alkali solution of a set concentration is provided below the containing tank (3), and the output end of the filling pipe (52) extends into the pre-storage tank (6).

4. The acetic anhydride production waste gas neutralization treatment equipment according to claim 1, characterized in that: The reflux assembly comprises a reflux pipe (7) connected to the container (3) and a second water pump (71) arranged on the reflux pipe (7), wherein the output end of the second water pump (71) is connected to the input end of the spray pipe (2).

Images