Method for removing nitrogen dioxide in dimethyl sulfoxide crude product

Abstract

The invention discloses a method for removing nitrogen dioxide in dimethyl sulfoxide, and particularly relates to a method for removing nitrogen dioxide in a dimethyl sulfoxide crude product in the process of producing dimethyl sulfoxide from dimethyl sulfide, oxygen and nitrogen dioxide. A dimethyl sulfoxide crude product is introduced into the reactor, and the high-purity dimethyl sulfoxide can be separated and recovered from the crude product by circularly and repeatedly blowing off the dimethyl sulfoxide crude product in a closed device through nitrogen. The production method is suitable for a technology for producing dimethyl sulfoxide through nitrogen dioxide liquid phase oxidation, nitrogen dioxide in the crude product dimethyl sulfoxide is removed, the loss amount of nitrogen dioxide in the air stripping treatment process is greatly reduced, the operation process is easy and convenient to control, and the production method is suitable for modification and upgrading of an existing similar dimethyl sulfoxide production technology.

Description

Technical Field

[0001] The invention discloses a method for removing nitrogen dioxide from dimethyl sulfoxide, and particularly relates to a method for removing nitrogen dioxide from dimethyl sulfoxide crude product in the process of producing dimethyl sulfoxide from dimethyl sulfide, oxygen and nitrogen dioxide. Background Art

[0002] Dimethyl sulfoxide (DMSO for short) is a widely used organic solvent. The mainstream production process in the industry is the liquid-phase emulsification oxidation process with dimethyl sulfide, nitrogen dioxide and oxygen as the main raw materials. A large amount of nitrogen dioxide is dissolved in the crude dimethyl sulfoxide produced by this production process. It is generally necessary to treat the nitrogen dioxide dissolved in the dimethyl sulfoxide by means of stripping, neutralization, etc. The treatment process has safety and technical problems that need to be solved urgently, such as large exhaust gas treatment volume, serious nitrogen dioxide loss, and great safety hazards in waste salt treatment.

[0003] With the continuous improvement of the concepts of green development, energy conservation, emission reduction and inherent safety, improving the utilization rate of oxidants and reducing the emission of three wastes are major challenges facing the industry. Summary of the invention

[0004] The invention discloses a method for removing nitrogen dioxide from crude dimethyl sulfoxide in the process of producing dimethyl sulfoxide from dimethyl sulfide, oxygen and nitrogen dioxide.

[0005] To achieve the above object, the technical solution adopted by the present invention is:

[0006] A method for removing nitrogen dioxide from a crude dimethyl sulfoxide product comprises the steps of introducing the crude dimethyl sulfoxide product into a reactor and repeatedly stripping the crude product with nitrogen gas to separate and recover high-purity dimethyl sulfoxide from the crude product.

[0007] Furthermore, the gas in the reactor is replaced by nitrogen, and the crude product is circulated and pumped into the reactor through a heat exchanger, and the crude product is repeatedly stripped by the internal circulation of nitrogen in the reactor. After the stripping, the gas flows into a condenser for condensation to separate nitrogen dioxide and nitrogen, and the nitrogen dioxide is recovered, and the nitrogen is returned to the reactor for recycling; the liquid recovered after the stripping is high-purity dimethyl sulfoxide.

[0008] More specifically:

[0009] (1) After the internal system of the reactor in the removal system is replaced with nitrogen, crude dimethyl sulfoxide containing nitrogen dioxide is quantitatively added, the circulation pump is turned on, the heat exchange medium temperature control of the heat exchanger is turned on, and the heat exchange medium temperature control of the condenser is turned on. The crude product is pumped into the heat exchanger through the circulation pump, and the crude product is kept in liquid under the action of the heat exchange medium. Then, the crude product flows into the reactor from the top of the reactor through the pipeline flow, and the nitrogen used is introduced into the reactor through the nitrogen inlet 7, and then the nitrogen inlet 7 is closed, so that the nitrogen gas reciprocates through the pipelines 12 and 18 and enters the bottom of the packing layer of the reactor through the gas-liquid mixer 19;

[0010] (2) The crude product flows into the reactor, and the nitrogen used for displacement in the reactor removes the nitrogen dioxide in the crude dimethyl sulfoxide product. The nitrogen strips the reaction liquid. The stripping gas (a mixture of nitrogen dioxide and nitrogen, with a small amount of dimethyl sulfoxide) is condensed in a condenser to separate the nitrogen dioxide and nitrogen. The nitrogen dioxide and the entrained dimethyl sulfoxide are recovered to a storage tank. The nitrogen returns to the reactor for recycling and returns to the bottom of the packing layer to continue stripping the reaction liquid. This cycle repeats.

[0011] (3) The liquid after stripping and separation is sampled through the sampling port 11 at the bottom of the reactor to detect the acid value of the material. After the removal requirement is met, it is discharged through the sample discharge port of the pipeline to obtain pure dimethyl sulfoxide.

[0012] The temperature control range of the heat exchange medium of the heat exchanger is between 20 and 200° C.; the heat exchange medium used is hot oil.

[0013] The temperature control range of the heat exchange medium of the condenser is between -20 and 30°C; the heat exchange medium used is 50% ethylene glycol aqueous solution.

[0014] The reactor pressure is controlled between -0.1 and 0.1 MPa (gauge pressure).

[0015] The straight section of the reactor body is cylindrical, a heat exchange jacket is arranged outside the kettle body, the top of the kettle body is a gas phase section, the middle of the kettle body is a packing section, the bottom of the kettle body is a gas-liquid mixing section, and a liquid level gauge is arranged outside the kettle body;

[0016] The packing is a structured packing, which may be a mesh corrugated packing, a plate hole corrugated packing, etc.;

[0017] A removal system of the method comprises a circulation pump 2, a heat exchanger 4, a reactor 8, a gas-liquid mixer 19 and a condenser 13, wherein the circulation pump 2, the heat exchanger 4, the gas-liquid mixer 19 and the reactor 8 are sequentially connected in series to form a closed loop, and a feed pipeline 1 is provided on the pipeline between the reactor 8 and the circulation pump 2, a second interface and a nitrogen inlet 7 are provided at the upper end of the reactor 8, and the input end of the condenser 13 is connected to the second interface through a condenser input pipeline 12; and the output end of the condenser 13 is connected to a first interface provided on the gas-liquid mixer 19 through a condenser output pipeline.

[0018] The gas-liquid mixer 19 is inserted into the reactor 8 .

[0019] A rotating shaft is provided inside the condenser 13, and a sliding scraper 13-3 is provided on the rotating shaft. A motor 13-1 is provided outside the condenser 13, and the rotating shaft is driven to rotate by the motor 13-1. A condenser jacket 13-2 is provided on the outer wall of the condenser 13, and a first heat exchange medium inlet 14 is provided at one end of the condenser jacket 13-2, and a first heat exchange medium outlet 15 is provided at the other end. A pressure control port 17 is provided at the output end of the condenser 13, and the pressure control port 17 is connected to the condenser receiving tank 16 through a pipeline.

[0020] A first temperature sensor, a first pressure sensor and a discharge port 3 are sequentially arranged on the pipeline between the circulation pump 2 and the heat exchanger 4 along the material flow direction;

[0021] The heat exchanger 4 is provided with a second heat exchange medium inlet 5 at one end and a second heat exchange medium outlet 6 at the other end;

[0022] A second temperature sensor is provided on the pipeline between the heat exchanger 4 and the reactor 8 .

[0023] A heat preservation jacket is provided on the outside of the reactor, and a third heat exchange medium inlet 9 is provided on one side of the heat preservation jacket, and a third heat exchange medium outlet 10 is provided on the other side. A second pressure sensor is provided on the upper end of the reactor 8.

[0024] A sampling port 11, a third temperature sensor and a third pressure sensor are sequentially arranged on the pipeline between the reactor 8 and the circulation pump 2 along the material transmission direction.

[0025] The crude liquid is pumped into the system through a circulation pump, and pure dimethyl sulfoxide is separated from the crude product after stripping and then discharged by the circulation pump, which serves as a cycle; the crude liquid circulation flow rate is adjusted within a range of 10-100 times / h.

[0026] The condenser is a sliding vane condenser.

[0027] The removal method of the invention has the following advantages: the removal of nitrogen dioxide in the crude dimethyl sulfoxide product in the process of producing dimethyl sulfoxide from dimethyl sulfide, oxygen and nitrogen dioxide is realized, the nitrogen is reciprocatedly stripped in the kettle for recycling, the stripped nitrogen dioxide and dimethyl sulfoxide are condensed and recovered through a condenser, the loss of nitrogen dioxide in the stripping and separation process is greatly reduced, and the cost of three wastes treatment in the dimethyl sulfoxide production process is reduced, thereby improving the production competitiveness of the process. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 The present invention provides a process flow chart of a method for removing nitrogen dioxide from dimethyl sulfoxide.

[0029] Figure 2 A schematic structural diagram of a sliding vane condenser used in the method of the present invention.

[0030] Among them, 1-dimethyl sulfoxide crude product metering feed, 2-circulation pump, 3-discharge port, 4-heat exchanger, 5-heat exchange medium inlet, 6-heat exchange medium outlet, 7-nitrogen inlet, 8-reactor body, 9-heat exchange medium inlet, 10-heat exchange medium outlet, 11-sampling port, 12-condenser gas phase inlet, 13-condenser, 14-cooling medium inlet, 15-cooling medium outlet, 16-condenser receiving tank, 17-pressure control port, 18-condenser gas phase outlet, 19-gas-liquid mixer, 13-1 rotating motor, 13-2 condenser jacket, 13-3 sliding scraper. DETAILED DESCRIPTION

[0031] The technical scheme and features of the present invention are described in detail through specific embodiments. The specific embodiments are included in but not limited to the present invention.

[0032] The present invention adopts the method of nitrogen internal circulation in the kettle to remove nitrogen dioxide in the crude dimethyl sulfoxide product, nitrogen is used to blow off the reaction liquid, and the gas separated by the blow-off (a mixture of nitrogen dioxide and nitrogen, and a small amount of dimethyl sulfoxide is entrained) is condensed by a condenser to separate nitrogen dioxide and nitrogen, and nitrogen dioxide and entrained dimethyl sulfoxide are recovered to the condenser receiving tank, and nitrogen is returned to the reactor for recycling in the kettle. By adopting this method, the loss of nitrogen dioxide in the blow-off treatment process is greatly reduced, and the operation process is simple to control, which is suitable for the transformation and upgrading of existing similar dimethyl sulfoxide production processes.

[0033] The invention uses nitrogen to circulate and blow off the reaction liquid in a reactor equipped with fillers under the conditions of pressure of -0.1 to 0.1Mpa, temperature of 20 to 200°C and circulation volume of 10 to 100 times / h. The nitrogen is circulated in the process, and the nitrogen dioxide in the crude dimethyl sulfoxide product is removed by adjusting the temperature and pressure of the equipment system and the circulation volume of the liquid. The acid value of the material can be lower than the index range of the technical requirements in the dimethyl sulfoxide product standard, and the loss of the oxidant in the blowing and stripping process is greatly reduced.

[0034] Example 1

[0035] like Figure 1 and 2 As shown,

[0036] A removal system of the method comprises a circulation pump 2, a heat exchanger 4, a reactor 8, a gas-liquid mixer 19 and a condenser 13, wherein the circulation pump 2, the heat exchanger 4, the gas-liquid mixer 19 and the reactor 8 are sequentially connected in series to form a closed loop, and a feed pipeline 1 is provided on the pipeline between the reactor 8 and the circulation pump 2, a second interface and a nitrogen inlet 7 are provided at the upper end of the reactor 8, and the input end of the condenser 13 is connected to the second interface through a condenser input pipeline 12; and the output end of the condenser 13 is connected to a first interface provided on the gas-liquid mixer 19 through a condenser output pipeline.

[0037] The gas-liquid mixer 19 is inserted into the reactor 8 .

[0038] A rotating shaft is provided inside the condenser 13, and a sliding scraper 13-3 is provided on the rotating shaft. A motor 13-1 is provided outside the condenser 13, and the rotating shaft is driven to rotate by the motor 13-1. A condenser jacket 13-2 is provided on the outer wall of the condenser 13, and a first heat exchange medium inlet 14 is provided at one end of the condenser jacket 13-2, and a first heat exchange medium outlet 15 is provided at the other end. A pressure control port 17 is provided at the output end of the condenser 13, and the pressure control port 17 is connected to the condenser receiving tank 16 through a pipeline.

[0039] A first temperature sensor, a first pressure sensor and a discharge port 3 are sequentially arranged on the pipeline between the circulation pump 2 and the heat exchanger 4 along the material flow direction;

[0040] The heat exchanger 4 is provided with a second heat exchange medium inlet 5 at one end and a second heat exchange medium outlet 6 at the other end;

[0041] A second temperature sensor is provided on the pipeline between the heat exchanger 4 and the reactor 8 .

[0042] A heat preservation jacket is provided on the outside of the reactor, and a third heat exchange medium inlet 9 is provided on one side of the heat preservation jacket, and a third heat exchange medium outlet 10 is provided on the other side. A second pressure sensor is provided on the upper end of the reactor 8.

[0043] A sampling port 11, a third temperature sensor and a third pressure sensor are sequentially arranged on the pipeline between the reactor 8 and the circulation pump 2 along the material transmission direction.

[0044] The straight section of the reactor body is cylindrical, a heat exchange jacket is arranged outside the kettle body, the top of the kettle body is a gas phase section, the middle of the kettle body is a packing section, the bottom of the kettle body is a gas-liquid mixing section, and a liquid level gauge is arranged outside the kettle body;

[0045] Example 2

[0046] The device described in the embodiment is used to separate nitrogen dioxide from crude dimethyl sulfoxide, wherein the heat exchange medium used in the reactor jacket is hot water, the condenser is 50% ethylene glycol, and the heat exchange medium used in the heat exchanger is hot oil; the reactor is a vertical cylindrical kettle structure, and the filler arranged inside is a mesh corrugated regular filler.

[0047] The specific separation is:

[0048] (1) Check the valve switch status of the system, introduce nitrogen into the internal system of the reactor in the removal system through the nitrogen inlet 7 for replacement, close the nitrogen inlet 7 after introducing a corresponding amount, and then quantitatively add 15.00 kg of crude dimethyl sulfoxide with a nitrogen dioxide content of 3.8% (wt), start the circulation pump, start the heat exchanger heat exchange medium to control the temperature to 80°C, start the condenser heat exchange medium to control the temperature to -10°C, and pump the crude product into the heat exchanger through the circulation pump. Under the action of the heat exchange medium, the crude product is kept in liquid form, and then flows from the top of the reactor through the gas-liquid mixer into the middle of the liquid phase area of ​​the reactor for gas-liquid stripping separation, and control the temperature of the crude product liquid added to the reactor to be 60°C, and the pressure of the reactor is 0.00 MPa (gauge pressure), and the circulation rate of the crude product liquid is 50 times / h;

[0049] (2) The crude product flows into the reactor, and the nitrogen used for replacement in the reactor (nitrogen dioxide in the crude dimethyl sulfoxide) is removed. The nitrogen in the reactor is reciprocated through pipelines 12 and 18 through the gas-liquid mixer 19 to enter the bottom of the reactor packing layer to strip the reaction liquid. The stripping gas (a mixture of nitrogen dioxide and nitrogen, with a small amount of dimethyl sulfoxide) is condensed by the condenser to separate nitrogen dioxide and nitrogen. The nitrogen dioxide and the entrained dimethyl sulfoxide are recovered to the storage tank, and the nitrogen is returned to the reactor for recycling, and then returned to the bottom of the packing layer to continue stripping the reaction liquid. This reciprocating cycle is continued for 5 hours;

[0050] (3) The liquid after stripping and separation is sampled through the sampling port 11 at the bottom of the reactor to detect the acid value of the material. The acid value of the material is measured to be 0.021 mgKOH / g, which meets the removal requirement. The liquid is discharged through the sample discharge port of the pipeline, and 14.13 kg of dimethyl sulfoxide with a purity of 99.5% is obtained.

[0051] Example 3

[0052] The system described in Example 1 was used for preparation, which differs from Example 2 in that 15.00 kg of crude dimethyl sulfoxide was added to the reactor 13, the nitrogen dioxide content was 5.0% (wt), the liquid temperature in the reactor was maintained at 60°C, the pressure was -0.05 MPa (gauge pressure), the circulation rate was 50 times / h, the stripping was continued for 3 hours, the acid value of the tested material was 0.016 mgKOH / g, and 13.82 kg of dimethyl sulfoxide with a purity of 99.6% was obtained.

[0053] Example 4

[0054] The system described in Example 1 was used for preparation, which differs from Example 2 in that 15.00 kg of crude dimethyl sulfoxide was added to reactor 13, the nitrogen dioxide content was 4.5% (wt), the liquid temperature in the kettle was maintained at 80°C, the pressure was 0.00 MPa (gauge pressure), the circulation rate was 50 times / h, the stripping was continued for 2 hours, the acid value of the tested material was 0.018 mgKOH / g, and 13.84 kg of dimethyl sulfoxide with a purity of 99.5% was obtained.

[0055] Example 5

[0056] The system described in Example 1 was used for preparation, which differs from Example 2 in that 15.00 kg of crude dimethyl sulfoxide was added to the reactor 13, the nitrogen dioxide content was 2.8% (wt), the liquid temperature in the reactor was maintained at 100°C, the pressure was 0.00 MPa (gauge pressure), the circulation rate was 40 times / h, the stripping was continued for 1.5 hours, the acid value of the tested material was 0.013 mgKOH / g, and 13.96 kg of dimethyl sulfoxide with a purity of 99.6% was obtained.

[0057] Example 6

[0058] The system described in Example 1 was used for preparation, which differs from Example 2 in that 15.00 kg of crude dimethyl sulfoxide was added to the reactor 13, the nitrogen dioxide content was 3.2% (wt), the liquid temperature in the reactor was maintained at 100°C, the pressure was -0.05 MPa (gauge pressure), the circulation rate was 40 times / h, the stripping was continued for 1 hour, the acid value of the tested material was 0.008 mgKOH / g, and 13.65 kg of dimethyl sulfoxide with a purity of 99.6% was obtained.

Claims

1. A method for removing nitrogen dioxide from crude dimethyl sulfoxide, characterized in that: The crude dimethyl sulfoxide is introduced into a reactor, and nitrogen is circulated and repeatedly blown off in a closed device, so that the crude product can be separated and recovered into high-purity dimethyl sulfoxide.

2. The method for removing nitrogen dioxide from crude dimethyl sulfoxide according to claim 1, characterized in that: The gas in the reactor is replaced by nitrogen, and the crude product is circulated and pumped into the reactor through a heat exchanger, and the crude product pumped in is repeatedly stripped by the internal circulation of nitrogen in the reactor. After stripping, the gas flows into a condenser for condensation to separate nitrogen dioxide and nitrogen, and the nitrogen dioxide is recovered, and the nitrogen is returned to the reactor for recycling; the liquid recovered after stripping is high-purity dimethyl sulfoxide.

3. The method for removing nitrogen dioxide from the crude dimethyl sulfoxide according to claim 2, characterized in that: The temperature control range of the heat exchange medium of the heat exchanger is between 20 and 200°C; The temperature control range of the condenser heat exchange medium is between -20 and 30°C; The reactor pressure is controlled between -0.1 and 0.1 MPa (gauge pressure).

4. A removal system according to the method of claim 1, characterized in that: The invention comprises a circulation pump 2, a heat exchanger 4, a reactor 8, a gas-liquid mixer 19 and a condenser 13, wherein the circulation pump 2, the heat exchanger 4, the gas-liquid mixer 19 and the reactor 8 are sequentially connected in series to form a closed loop, and a feed pipeline 1 is provided on the pipeline between the reactor 8 and the circulation pump 2, a second interface and a nitrogen inlet 7 are provided on the upper end of the reactor 8, and the input end of the condenser 13 is connected to the second interface through a condenser input pipeline 12; and the output end of the condenser 13 is connected to a first interface provided on the gas-liquid mixer 19 through a condenser output pipeline.

5. The removal system according to claim 4, characterized in that: A rotating shaft is provided inside the condenser 13, and a sliding scraper 13-3 is provided on the rotating shaft. A motor 13-1 is provided outside the condenser 13, and the rotating shaft is driven to rotate by the motor 13-1. A condenser jacket 13-2 is provided on the outer wall of the condenser 13, and a first heat exchange medium inlet 14 is provided at one end of the condenser jacket 13-2, and a first heat exchange medium outlet 15 is provided at the other end. A pressure control port 17 is provided at the output end of the condenser 13, and the pressure control port 17 is connected to the condenser receiving tank 16 through a pipeline.

6. The removal system according to claim 4, characterized in that: A first temperature sensor, a first pressure sensor and a discharge port 3 are sequentially arranged on the pipeline between the circulation pump 2 and the heat exchanger 4 along the material flow direction; The heat exchanger 4 is provided with a second heat exchange medium inlet 5 at one end and a second heat exchange medium outlet 6 at the other end; A second temperature sensor is provided on the pipeline between the heat exchanger 4 and the reactor 8 .

7. The removal system according to claim 4, characterized in that: A heat preservation jacket is provided on the outside of the reactor, and a third heat exchange medium inlet 9 is provided on one side of the heat preservation jacket, and a third heat exchange medium outlet 10 is provided on the other side. A second pressure sensor is provided on the upper end of the reactor 8.

8. The removal system according to claim 4, characterized in that: A sampling port 11, a third temperature sensor and a third pressure sensor are sequentially arranged on the pipeline between the reactor 8 and the circulation pump 2 along the material transmission direction.

9. The removal system according to any one of claims 1 to 8, characterized in that: The crude liquid is pumped into the system through a circulation pump, and pure dimethyl sulfoxide is separated from the crude product after stripping and then discharged by the circulation pump, which serves as a cycle; the crude liquid circulation flow rate is adjusted within a range of 10-100 times / h.

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