A continuous purification method and production equipment for hydrochloric acid, a byproduct of acyl chloride production.

Abstract

This invention discloses a continuous purification method and equipment for hydrochloric acid, a byproduct of acyl chloride production, belonging to the field of separation and purification technology. The method uses an extractant to extract crude hydrochloric acid. Since sulfur and sulfur dioxide are readily soluble in extractants such as carbon disulfide, but these extractants have very low solubility in water, and the presence of hydrogen chloride makes it easy for sulfur dioxide in the hydrochloric acid to be extracted into the extractant, this invention utilizes this property to achieve a continuous extraction, separation, and purification method for hydrochloric acid during acyl chloride production. Compared to traditional batch methods for purifying hydrochloric acid, the continuous extraction and separation method significantly increases the hourly product yield, resulting in higher efficiency. Furthermore, the use of flash evaporation makes it more efficient and energy-saving than traditional filtration and distillation methods.

Description

Technical Field

[0001] This invention belongs to the field of separation and purification technology, specifically relating to a continuous purification method and production equipment for hydrochloric acid, a byproduct of acyl chloride production. Background Technology

[0002] Acyl chlorides are important organic synthesis intermediates, mainly used in the synthesis of fine chemicals such as pharmaceuticals and pesticides, as well as in the synthesis of organic intermediates. Among common acyl chloride synthesis methods, the synthesis of acyl chlorides from thionyl chloride and organic acids is a frequent approach. The byproduct hydrogen chloride is often absorbed by water, becoming hydrochloric acid. However, the main components of this byproduct hydrochloric acid are typically 21%-30% hydrogen chloride (mass fraction), 1.5%-3.8% sulfur dioxide, and 0.5%-2% sulfur, with the remainder being water. It can be seen that the impurities such as elemental sulfur and dissolved sulfur dioxide in this type of hydrochloric acid reduce its quality and significantly limit its application. Therefore, purification is necessary. For ordinary hydrochloric acid, methods such as distillation, adsorption, and washing are commonly used for purification. For example, in patent CN104211013B, a combination of adsorption, washing, and condensation is used to prepare hydrochloric acid that meets the requirements for superior grade in the high-purity hydrochloric acid industry standard HG / T2778-2009. However, this method is not applicable to hydrochloric acid containing sulfur. Since sulfur is dispersed in the hydrochloric acid system in the form of extremely fine particles, it is difficult to separate it using common filtration methods. Furthermore, the fine sulfur particles can easily clog the filtration device and filter cloth. Therefore, the filtration method has significant drawbacks in industrial applications.

[0003] Of course, for sulfur dioxide in hydrochloric acid, a byproduct of acyl chloride production, numerous published documents have used absorption or distillation methods for separation and purification. For example, CN110898618A discloses a separation system and method for a mixture of hydrogen chloride and sulfur dioxide. The separation system includes an absorption tower, a condenser, and a pump. This invention uses a reflux pipeline to return a portion of the bottom liquid to the top of the tower, where it is mixed with process water and used as an absorbent, essentially using dilute acid as the absorbent to inhibit the transfer of sulfur dioxide into the liquid phase. This invention also dilutes and heats the gas phase containing a high amount of sulfur dioxide in the lower section of the tower by directly passing steam through the bottom of the tower, while simultaneously stripping the liquid phase with steam, significantly reducing the sulfur dioxide content in the bottom liquid. However, the hydrochloric acid produced using this method still contains a certain amount of sulfur dioxide impurities. Alternatively, there are technical solutions that utilize oxidants such as hydrogen peroxide to oxidize sulfur dioxide in hydrochloric acid to sulfuric acid, followed by distillation to separate the hydrochloric acid and sulfuric acid.

[0004] The aforementioned existing technologies employ complex equipment for distillation processes, including multiple distillation columns and numerous pipelines. Furthermore, the mixture of sulfur dioxide and hydrogen chloride is a highly protic acid, requiring expensive corrosion-resistant materials for the equipment, resulting in high equipment costs. Additionally, the distillation process inevitably necessitates vacuuming, consuming significant amounts of electricity and hindering carbon reduction. Therefore, finding a simple and efficient method to purify this type of hydrochloric acid is a pressing and crucial technical challenge in acyl chloride production. Summary of the Invention

[0005] In order to overcome the shortcomings of the prior art, the present invention aims to provide a continuous purification method and production equipment for hydrochloric acid, a byproduct of acyl chloride production, so as to solve the technical problem that sulfur-containing hydrochloric acid, a byproduct of acyl chloride production, cannot be continuously and efficiently purified.

[0006] To achieve the above objectives, the present invention employs the following technical solution:

[0007] This invention discloses a continuous purification method for hydrochloric acid, a byproduct of acyl chloride production, comprising the following steps:

[0008] 1) At room temperature, the extractant and crude hydrochloric acid produced during the production of acyl chloride are thoroughly mixed and extracted to obtain a mixed extract;

[0009] 2) Centrifuge the mixed extract to separate the lighter product, which is the purified hydrochloric acid product, and collect it; heat the heavier extract containing sulfur and sulfur dioxide after centrifugation and flash evaporate it. The gas components after flash evaporation are condensed and the resulting extractant is returned to step 1) for reuse. The uncondensed sulfur dioxide gas is absorbed by alkaline solution to become sodium bisulfite solution, a byproduct. The remaining substance after flash evaporation is sulfur.

[0010] Preferably, the mass percentage of crude hydrochloric acid produced from the production of acyl chloride is 21% to 30%.

[0011] Preferably, in step 1), the feed volume ratio of the extractant to the crude hydrochloric acid produced from the production of acyl chloride is 1:(1.3 to 2.6).

[0012] Preferably, the extractant is one of carbon disulfide, vinyl sulfite, propylene sulfite, dimethyl sulfite, and diethyl sulfite.

[0013] Preferably, in step 1), the mixing and extraction is carried out in a microchannel reactor, the pressure in the microchannel reactor is 0.8MPa-1.8MPa, and the mixing and extraction temperature is 5-18℃.

[0014] Preferably, in step 2), the centrifugal rotation speed is 1300-1550 rpm.

[0015] Preferably, in step 2), the heating temperature is 52-65℃.

[0016] The present invention also discloses production equipment for realizing the above-mentioned continuous purification method for producing hydrochloric acid, a byproduct of acyl chloride production, including: an extractant storage tank, a crude hydrochloric acid storage tank, a microchannel reactor, a centrifuge, a pure hydrochloric acid storage tank, a heating tank, a flash tank, a condenser, an extractant product collection tank, and a sulfur dioxide absorption tank.

[0017] The extractant from the extractant storage tank and the hydrochloric acid from the crude hydrochloric acid storage tank are continuously fed into a microchannel reactor for thorough mixing and extraction. After extraction, the immiscible hydrochloric acid and extractant are centrifuged. The less dense hydrochloric acid is discharged from the light component outlet and transported to the pure hydrochloric acid storage tank, achieving continuous separation of hydrochloric acid. The more dense heavy component extract is discharged from the heavy component outlet and sent to a heating tank for heating treatment. The heated mixture is continuously transported to a flash tank, where sulfur dioxide in the mixture is converted into gas and evaporated. The extractant is condensed into liquid by a condenser and collected in the extractant product collection tank, and then transported to the extractant storage tank for reuse. The uncondensed gaseous sulfur dioxide enters the sulfur dioxide absorption tank and is absorbed as the byproduct sodium bisulfite solution. The remaining substance in the flash tank is solid sulfur, which is heated and melted before being discharged as a byproduct for recovery.

[0018] Preferably, the pressure in the microchannel reactor is maintained at 0.8MPa-1.8MPa, the temperature required for mixing and extraction is provided by the refrigerant in the jacket located outside the microchannel reactor, and the condensation temperature is maintained at 5-18℃.

[0019] Preferably, the centrifuge speed is maintained at 1300-1550 rpm; the sulfur dioxide absorption tank is filled with sodium hydroxide solution for absorbing gaseous sulfur dioxide.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] This invention discloses a continuous purification method for hydrochloric acid, a byproduct of acyl chloride production. Extraction is performed using an extractant. Since sulfur and sulfur dioxide are readily soluble in extractants such as carbon disulfide, but these extractants have very low solubility in water, and the presence of hydrogen chloride facilitates the extraction of sulfur dioxide from the hydrochloric acid into the extractant, this invention utilizes this property to achieve a continuous extraction, separation, and purification method for hydrochloric acid during acyl chloride production. Compared to traditional batch methods for purifying hydrochloric acid, the continuous extraction and separation method significantly increases the hourly product yield, resulting in higher efficiency. Furthermore, the use of flash evaporation makes it more efficient and energy-saving than traditional filtration and distillation methods. The hydrochloric acid prepared using this method has high purity, making it suitable for applications in pharmaceuticals and other fields requiring high purity hydrochloric acid.

[0022] This invention also discloses production equipment for implementing the above-mentioned continuous purification method, employing devices such as microchannel reactors, centrifugal separation, and flash evaporation. This allows hydrochloric acid to be rapidly, energy-efficiently, and effectively mixed and separated from impurities such as sulfur and sulfur dioxide throughout the purification process. Furthermore, compared to traditional distillation columns, the microchannel reactor, centrifuge, and flash evaporation devices in this invention are small in size and contain a small amount of liquid, resulting in a smaller footprint for the entire production equipment. Even in the event of a leak, the consequences are significantly less severe than with traditional equipment. Therefore, this invention offers advantages such as high safety, small footprint, and high degree of automation. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the continuous purification production equipment for the production of hydrochloric acid, a byproduct of acyl chloride, according to the present invention.

[0024] Wherein: 1-Hydrochloric acid inlet; 2-Carbon disulfide inlet; 3-Mixed inlet; 4-Mixed extract material outlet; 5-Centrifuge inlet; 6-Light component outlet; 7-Pure hydrochloric acid storage tank inlet; 8-Heavy component outlet; 9-Heating tank inlet; 10-Heating tank outlet; 11-Flash tank inlet; 12-Flash tank gas outlet; 13-Gas inlet; 14-Condensate reflux inlet; 15-Condensate outlet; 16-Carbon disulfide outlet; 17-Sulfur dioxide gas absorption inlet; 18-Sulfur dioxide absorbent outlet; 19-Microchannel reactor refrigerant inlet; 20-Microchannel reactor refrigerant outlet; 21-Heating tank heat medium inlet; 22-Heating tank heat medium outlet; 23-Flash tank heat medium inlet; 24-Flash tank heat medium outlet; 25-Condenser refrigerant inlet; 26-Condenser refrigerant outlet; 27-Hot and cold medium inlet; 28-Heat medium outlet; 29-Sulfur discharge outlet;

[0025] V1 - Extractant storage tank; V2 - Crude hydrochloric acid storage tank; V3 - Heating tank; V4 - Flash evaporator; V5 - Extractant product collection tank; V6 - Sulfur dioxide absorption tank; V7 - Pure hydrochloric acid storage tank; R1 - Microchannel reactor; C1 - Centrifuge; E1 - Condenser. Detailed Implementation

[0026] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0027] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0028] The present invention will now be described in further detail with reference to the accompanying drawings:

[0029] This invention discloses a continuous purification method for hydrochloric acid, a byproduct of acyl chloride production, comprising the following steps:

[0030] 1) At room temperature, the extractant and crude hydrochloric acid produced from the production of acyl chloride are thoroughly mixed and extracted in a preset ratio to obtain a mixed extract;

[0031] 2) Centrifuge the mixed extract to separate the less dense product, which is the purified hydrochloric acid product, and collect it;

[0032] The extract containing sulfur and sulfur dioxide separated by centrifugation is heated and then flash-evaporated. The gas components after flash evaporation are condensed to obtain the extractant, which is returned to step 1) for reuse. The uncondensed sulfur dioxide gas is absorbed by alkaline solution to obtain sodium bisulfite solution as a byproduct. The remaining substance after flash evaporation is sulfur as a byproduct.

[0033] Furthermore, in step 1) of this technical solution, the applicable hydrochloric acid mass percentage concentration is 21%-30%;

[0034] Furthermore, in step 1) of the technical solution, the feed volume ratio of crude hydrochloric acid to extractant is (1.3-2.6):1.

[0035] Furthermore, in step 1) of the technical solution, the liquid is mixed and extracted in a microchannel reactor, the pressure in the microchannel reactor is 0.8MPa-1.8MPa, and the mixing and extraction temperature is 5-18℃.

[0036] Furthermore, in step 2) of the technical solution, the rotation speed during centrifugation is 1300-1550 rpm.

[0037] Furthermore, in step 2) of the technical solution, the heating temperature is 52-65℃.

[0038] Furthermore, during condensation, the extractant is collected after cooling to below 18°C.

[0039] Furthermore, the extractant is one of carbon disulfide, vinyl sulfite, propylene sulfite, dimethyl sulfite, and diethyl sulfite.

[0040] See Figure 1 The present invention also discloses a reaction apparatus for realizing the continuous purification method of hydrochloric acid, a byproduct of the above-mentioned acyl chloride, comprising an extractant storage tank V1, a crude hydrochloric acid storage tank V2, a microchannel reactor R1, a centrifuge C1, a pure hydrochloric acid storage tank V7, a heating tank V3, a flash evaporator V4, a condenser E1, an extractant product collection tank V5, and a sulfur dioxide absorption tank V6.

[0041] The continuous operation achieved by this device consists of the following steps:

[0042] 1. Continuous mixed extraction

[0043] At a certain temperature, the extractant in the extractant storage tank V1 and the hydrochloric acid (such as crude hydrochloric acid for the production of propionyl chloride) in the crude hydrochloric acid storage tank V2 are simultaneously pumped into the microchannel reactor R1 through the mixing inlet 3 for reaction. The feed volume ratio of hydrochloric acid to extractant is (1.3-2.6):1. The pressure in the microchannel reactor R1 is 0.8MPa-1.8MPa. The mixing extraction temperature is provided by the coolant in the jacket of the microchannel reactor (entering from the coolant inlet 19 and exiting from the coolant outlet 20), and the temperature is maintained at 5-18℃.

[0044] 2. Continuous separation

[0045] After mixing and extraction, the immiscible hydrochloric acid and carbon disulfide are continuously fed into centrifuge C1 through centrifuge inlet 5 via the mixed extraction material outlet 4. As the centrifuge C1 rotates, the denser heavy component, carbon disulfide, is discharged from the outer heavy component outlet 8, while the less dense hydrochloric acid, which is insoluble with carbon disulfide, is discharged from the inner light component outlet 6 and enters the pure hydrochloric acid storage tank V7 through the pure hydrochloric acid storage tank inlet 7, thus achieving continuous separation of hydrochloric acid.

[0046] During the separation process described above, the centrifuge C1 is kept at a speed of 1300-1550 rpm, which can smoothly achieve the continuous separation of two immiscible liquid materials.

[0047] 3. Continuous separation of carbon disulfide extract

[0048] Hot water heating (heat medium inlet 21, heat medium outlet 22) is used to heat the carbon disulfide extractant in heating tank V3 to 52-65℃. The heated extractant is then continuously pumped into flash tank V4 from flash tank inlet 11. The sulfur dioxide in the mixture is converted to gas and evaporates from flash tank gas outlet 12. The carbon disulfide is condensed into liquid by condenser E1 and collected from condensate outlet 15 into product extractant collection tank V5. It is then recycled to extractant storage tank V1 via carbon disulfide outlet 16 for reuse. The remaining substance in flash tank V4 is solid sulfur, which is heated and melted after a period of time and discharged as a byproduct. The uncondensed gaseous sulfur dioxide from condenser E1 enters sulfur dioxide absorption tank V6 containing sodium hydroxide solution and is absorbed as a byproduct sodium bisulfite solution, which is discharged and collected through sulfur dioxide absorption liquid outlet.

[0049] The present invention will be further described in detail below with reference to embodiments:

[0050] Example 1

[0051] A continuous purification method for hydrochloric acid, a byproduct of acyl chloride production, includes the following steps:

[0052] Open the valves on the microchannel reactor coolant inlet 19 and the microchannel reactor coolant outlet 20 of the jacket on the microchannel reactor R1 to control the coolant temperature at 5°C. Under stirring, mix carbon disulfide in the extractant storage tank V1 at a rate of 110 L / h and 21% hydrochloric acid in the crude hydrochloric acid storage tank V2 at a rate of 286 L / h (i.e., the volume ratio of hydrochloric acid to carbon disulfide is 2.6:1), and then introduce the mixture into the microchannel reactor R1 through the mixing inlet 3, maintaining the reaction temperature at 5°C and the pressure at 0.8 MPa. The reacted liquid enters centrifuge C1 from the mixed extract outlet 4 via centrifuge inlet 5, maintaining a centrifuge speed of 1300 rpm. The extracted hydrochloric acid is discharged from the light component outlet 6 into the pure hydrochloric acid storage tank V7. The separated heavy component, carbon disulfide extract, is discharged from the heavy component outlet 8 into the heating tank V3, heated to 52°C, and then pumped from the heating tank outlet 10 into the flash tank inlet 11 into the flash tank V4. After flash evaporation, sulfur dioxide, in a gaseous state, is discharged from the flash tank gas outlet 12, cooled to below 18°C ​​by condenser E1, and enters the extractant product collection tank V5, circulating back to the extractant storage tank V1 for reuse. Uncondensed sulfur dioxide enters the sulfur dioxide absorption tank V6 containing a 30% sodium hydroxide solution for absorption as a sodium bisulfite solution byproduct. The remaining substance in the flash tank V4 is sulfur, which is discharged through the sulfur outlet 29 after a period of time.

[0053] Example 2

[0054] A continuous purification method for hydrochloric acid, a byproduct of acyl chloride production, includes the following steps:

[0055] Open the valves on the microchannel reactor coolant inlet 19 and the microchannel reactor coolant outlet 20 of the jacket on the microchannel reactor R1, and control the coolant temperature to 18°C. Under stirring, mix carbon disulfide in the extractant storage tank V1 at a rate of 110 L / h and 30% hydrochloric acid in the crude hydrochloric acid storage tank V2 at a rate of 143 L / h (i.e., the volume ratio of hydrochloric acid to carbon disulfide is 1.3:1), and then enter the microchannel reactor R1 through the mixing inlet 3. Maintain the reaction temperature at 18°C ​​and the pressure at 1.8 MPa. The reacted liquid enters centrifuge C1 from the mixed extract outlet 4 via centrifuge inlet 5, maintaining a centrifuge speed of 1550 rpm. The extracted hydrochloric acid is discharged from the light component outlet 6 into the pure hydrochloric acid storage tank V7. The separated heavy component, carbon disulfide extract, is discharged from the heavy component outlet 8 into the heating tank V3, heated to 65°C, and then pumped from the heating tank outlet 10 into the flash tank inlet 11 into the flash tank V4. After flash evaporation, sulfur dioxide, in a gaseous state, is discharged from the flash tank gas outlet 12, cooled to below 18°C ​​by condenser E1, and enters the extractant product collection tank V5, circulating back to the extractant storage tank V1 for reuse. Uncondensed sulfur dioxide enters the sulfur dioxide absorption tank V6 containing a 30% sodium hydroxide solution for absorption as a sodium bisulfite solution byproduct. The remaining substance in the flash tank V4 is sulfur, which is discharged through the sulfur outlet 29 after a period of time.

[0056] Example 3

[0057] A continuous purification method for hydrochloric acid, a byproduct of acyl chloride production, includes the following steps:

[0058] Open the valves on the microchannel reactor coolant inlet 19 and the microchannel reactor coolant outlet 20 of the jacket on the microchannel reactor R1, and control the coolant temperature to 12℃. Under stirring, mix carbon disulfide in the extractant storage tank V1 at a rate of 110L / h and 25% hydrochloric acid in the crude hydrochloric acid storage tank V2 at a rate of 220L / h (i.e., the volume ratio of hydrochloric acid to carbon disulfide is 2.0:1), and then enter the microchannel reactor R1 through the mixing inlet 3. Maintain the reaction temperature at 10℃ and the pressure at 1.2MPa. The reacted liquid enters centrifuge C1 from the mixed extract outlet 4 via centrifuge inlet 5, maintaining a centrifuge speed of 1450 rpm. The extracted hydrochloric acid is discharged from the light component outlet 6 into the pure hydrochloric acid storage tank V7. The separated heavy component, carbon disulfide extract, is discharged from the heavy component outlet 8 into the heating tank V3, heated to 55°C, and then pumped from the heating tank outlet 10 into the flash tank inlet 11 into the flash tank V4. After flash evaporation, sulfur dioxide, in a gaseous state, is discharged from the flash tank gas outlet 12, cooled to below 18°C ​​by condenser E1, and enters the extractant product collection tank V5, circulating back to the extractant storage tank V1 for reuse. Uncondensed sulfur dioxide enters the sulfur dioxide absorption tank V6 containing a 30% sodium hydroxide solution for absorption as a sodium bisulfite solution byproduct. The remaining substance in the flash tank V4 is sulfur, which is discharged through the sulfur outlet 29 after a period of time.

[0059] Example 4

[0060] A continuous purification method for hydrochloric acid, a byproduct of acyl chloride production, includes the following steps:

[0061] Open the valves on the microchannel reactor coolant inlet 19 and the microchannel reactor coolant outlet 20 of the jacket on the microchannel reactor R1, and control the coolant temperature to 14℃. Under stirring, mix the vinyl sulfite in the extractant storage tank V1 at a rate of 110L / h and the 25% hydrochloric acid in the crude hydrochloric acid storage tank V2 at a rate of 220L / h (i.e., the volume ratio of hydrochloric acid to vinyl sulfite is 1.8:1), and then enter the microchannel reactor R1 through the mixing inlet 3. Maintain the reaction temperature at 12℃ and the pressure at 1.2MPa. The reacted liquid enters centrifuge C1 from the mixed extract outlet 4 via centrifuge inlet 5, maintaining a centrifuge speed of 1300 rpm. The extracted hydrochloric acid is discharged from the light component outlet 6 into the pure hydrochloric acid storage tank V7. The separated heavy component extract is discharged from the heavy component outlet 8 into the heating tank V3, heated to 52°C, and then pumped from the heating tank outlet 10 into the flash tank inlet 11 into the flash tank V4. After flash evaporation, sulfur dioxide is discharged as a gas from the flash tank gas outlet 12. Vinyl sulfite is cooled to below 18°C ​​by condenser E1 and enters the extractant product collection tank V5, circulating back to the extractant storage tank V1 for reuse. Uncondensed sulfur dioxide enters the sulfur dioxide absorption tank V6 containing a 30% sodium hydroxide solution for absorption as a sodium bisulfite solution byproduct. The remaining substance in the flash tank V4 is sulfur, which is discharged through the sulfur outlet 29 after a period of time.

[0062] Example 5

[0063] A continuous purification method for hydrochloric acid, a byproduct of acyl chloride production, includes the following steps:

[0064] Open the valves on the microchannel reactor coolant inlet 19 and the microchannel reactor coolant outlet 20 of the jacket on the microchannel reactor R1, and control the coolant temperature to 12℃. Under stirring, mix the dimethyl sulfite in the extractant storage tank V1 at a rate of 110L / h and the 25% hydrochloric acid in the crude hydrochloric acid storage tank V2 at a rate of 220L / h (i.e., the volume ratio of hydrochloric acid to dimethyl sulfite is 1.8:1), and then enter the microchannel reactor R1 through the mixing inlet 3. Maintain the reaction temperature at 10℃ and the pressure at 1.2MPa. The reacted liquid enters centrifuge C1 from the mixed extract outlet 4 via centrifuge inlet 5, maintaining a centrifuge speed of 1500 rpm. The extracted hydrochloric acid is discharged from the light component outlet 6 into the pure hydrochloric acid storage tank V7. The separated heavy component extract is discharged from the heavy component outlet 8 into the heating tank V3, heated to 60°C, and then pumped from the heating tank outlet 10 into the flash tank inlet 11 into the flash tank V4. After flash evaporation, sulfur dioxide is discharged as a gas from the flash tank gas outlet 12. Dimethyl sulfite is cooled to below 18°C ​​by condenser E1 and enters the extractant product collection tank V5, circulating back to the extractant storage tank V1 for reuse. Uncondensed sulfur dioxide enters the sulfur dioxide absorption tank V6 containing a 30% sodium hydroxide solution for absorption as a sodium bisulfite solution byproduct. The remaining substance in the flash tank V4 is sulfur, which is discharged through the sulfur outlet 29 after a period of time.

[0065] Example 6

[0066] A continuous purification method for hydrochloric acid, a byproduct of acyl chloride production, includes the following steps:

[0067] Open the valves on the microchannel reactor coolant inlet 19 and the microchannel reactor coolant outlet 20 of the jacket on the microchannel reactor R1, and control the coolant temperature to 12℃. Under stirring, mix the diethyl sulfite in the extractant storage tank V1 at a rate of 110L / h and the 25% hydrochloric acid in the crude hydrochloric acid storage tank V2 at a rate of 220L / h (i.e., the volume ratio of hydrochloric acid to diethyl sulfite is 2.5:1), and then enter the microchannel reactor R1 through the mixing inlet 3. Maintain the reaction temperature at 10℃ and the pressure at 1.5MPa. The reacted liquid enters centrifuge C1 from the mixed extract outlet 4 via centrifuge inlet 5, maintaining a centrifuge speed of 1550 rpm. The extracted hydrochloric acid is discharged from the light component outlet 6 into the pure hydrochloric acid storage tank V7. The separated heavy component extract is discharged from the heavy component outlet 8 into the heating tank V3, heated to 65°C, and then pumped from the heating tank outlet 10 into the flash tank inlet 11 into the flash tank V4. After flash evaporation, sulfur dioxide is discharged as a gas from the flash tank gas outlet 12. Diethyl sulfite is cooled to below 18°C ​​by condenser E1 and enters the extractant product collection tank V5, circulating back to the extractant storage tank V1 for reuse. Uncondensed sulfur dioxide enters the sulfur dioxide absorption tank V6 containing a 30% sodium hydroxide solution for absorption as a sodium bisulfite solution byproduct. The remaining substance in the flash tank V4 is sulfur, which is discharged through the sulfur outlet 29 after a period of time.

[0068] The purity of the hydrochloric acid product obtained in the above examples was tested, and the results are shown in Table 1 below:

[0069] Table 1. Purity of hydrochloric acid products purified in Examples 1-6

[0070]

[0071] The experimental results show that the hydrochloric acid product obtained by using the method of the present invention has high purity and can ensure that the hydrochloric acid product does not contain elemental sulfur or sulfur dioxide. This can effectively solve the technical problem of sulfur impurities in hydrochloric acid during the current acyl chloride production process, thereby effectively improving the quality of hydrochloric acid.

[0072] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. A continuous purification method for hydrochloric acid, a byproduct of acyl chloride production, characterized in that, Includes the following steps: 1) At room temperature, the extractant and crude hydrochloric acid produced from the production of acyl chloride are thoroughly mixed and extracted in a microchannel reactor to obtain a mixed extract; 2) Centrifuge the mixed extract to separate the lighter product, which is the purified hydrochloric acid product, and collect it; heat the heavier extract containing sulfur and sulfur dioxide after centrifugation and flash evaporate it. The gas components after flash evaporation are condensed and the resulting extractant is returned to step 1) for reuse. The uncondensed sulfur dioxide gas is absorbed by alkaline solution to become sodium bisulfite solution, a byproduct. The remaining substance after flash evaporation is sulfur.

2. The continuous purification method for hydrochloric acid, a byproduct of acyl chloride production, according to claim 1, is characterized in that, The crude hydrochloric acid produced during the production of acyl chlorides accounts for 21% to 30% by mass.

3. The continuous purification method for hydrochloric acid, a byproduct of acyl chloride production, according to claim 1, is characterized in that, In step 1), the feed volume ratio of the extractant to the crude hydrochloric acid produced from the production of acyl chloride is 1:(1.3~2.6).

4. The continuous purification method for hydrochloric acid, a byproduct of acyl chloride production, according to claim 1, is characterized in that, The extractant is one of carbon disulfide, vinyl sulfite, propylene sulfite, dimethyl sulfite, and diethyl sulfite.

5. The continuous purification method for hydrochloric acid, a byproduct of acyl chloride production, according to claim 1, is characterized in that, In step 1), the pressure in the microchannel reactor is 0.8MPa-1.8MPa; the mixing and extraction temperature is 5-18℃.

6. The continuous purification method for hydrochloric acid, a byproduct of acyl chloride production, according to claim 1, is characterized in that, In step 2), the centrifugation speed is 1300-1550 rpm.

7. The continuous purification method for hydrochloric acid, a byproduct of acyl chloride production, according to claim 1, is characterized in that, In step 2), the heating temperature is 52-65℃.

8. A production apparatus for implementing the continuous purification method for producing hydrochloric acid, a byproduct of acyl chloride production, as described in any one of claims 1 to 7, characterized in that, include: Extractant storage tank (V1), crude hydrochloric acid storage tank (V2), microchannel reactor (R1), centrifuge (C1), pure hydrochloric acid storage tank (V7), heating tank (V3), flash tank (V4), condenser (E1), extractant product collection tank (V5), and sulfur dioxide absorption tank (V6). The extractant in the extractant storage tank (V1) and the hydrochloric acid in the crude hydrochloric acid storage tank (V2) are continuously fed into the microchannel reactor (R1) for thorough mixing and extraction. After extraction, the immiscible hydrochloric acid and extractant are centrifuged in a centrifuge (C1). The less dense hydrochloric acid is discharged from the light component outlet and transported to the pure hydrochloric acid storage tank (V7) to achieve continuous separation of hydrochloric acid. The extract of the more dense heavy component is discharged from the heavy component outlet and sent to the heating tank (V3) for heating treatment. The heated mixture is continuously transported to the flash tank (V4), where the sulfur dioxide in the mixture is converted into gas and evaporated. The extractant is condensed into liquid by the condenser (E1) and collected in the extractant product collection tank (V5), and then transported to the extractant storage tank (V1) for reuse. The uncondensed gaseous sulfur dioxide enters the sulfur dioxide absorption tank (V6) and is absorbed as the by-product sodium bisulfite solution. The remaining substance in the flash tank (V4) is solid sulfur, which is heated and melted and discharged as a by-product for recovery.

9. The production equipment according to claim 8, characterized in that, The pressure in the microchannel reactor (R1) is maintained at 0.8MPa-1.8MPa. The temperature required for mixing and extraction is provided by the refrigerant in the jacket located outside the microchannel reactor (R1), and the condensation temperature is maintained at 5-18℃.

10. The production equipment according to claim 8, characterized in that, The centrifuge (C1) is kept at a speed of 1300-1550 rpm; the sulfur dioxide absorption tank (V6) is filled with sodium hydroxide solution for absorbing gaseous sulfur dioxide.

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