NVP production tubular reactor

Abstract

The utility model provides a tubular reactor for NVP production, and relates to the technical field of chemical industry and medicine industry. Aiming at the problems of difficulty in reaction heat control, short gas-liquid contact time, non-uniform gas distribution and the like in the NVP synthesis process, efficient gas-liquid mixing is realized through the Venturi ejector, the reaction conversion rate and selectivity are improved by utilizing the series connection of the multi-stage tubular reactors, the reaction temperature and pressure are accurately controlled, and the production safety is ensured. Experimental results show that the NVP synthesis efficiency and the product quality are remarkably improved.

Description

TECHNICAL FIELD

[0001] The utility model relates to the technical field of chemical and pharmaceutical industry, specifically relates to a NVP production tubular reactor. BACKGROUND

[0002] N-vinyl pyrrolidone (NVP) is an important chemical and pharmaceutical intermediate, which is widely used in the fields of medicine, cosmetics, paint, adhesive and the like.

[0003] At present, the production process of NVP is mainly acetylene method. The acetyylene method uses acetylene and 2-pyrrolidone (2-P) as raw materials, and generates NVP under the action of catalyst (2-pyrrolidone potassium) by addition reaction. However, in the production process of NVP, gas-liquid two-phase reaction is a key link and also a technical difficulty.

[0004] In the related art, the gas-liquid two-phase counterflow bubble reactor has obvious deficiencies in the NVP synthesis process. Due to the intense release of reaction heat, the temperature is difficult to stabilize and control; the gas-liquid contact time is short, which affects the reaction conversion rate; the length-diameter ratio of the reactor is large, which increases the back mixing and brings difficulty to the subsequent rectification separation. In addition, the NVP synthesis reaction also has the difficulties of unstable activity of pyrrolidone potassium, low solubility of acetylene, flammability and explosiveness. INVENTION CONTENTS

[0005] (I) Technical problems solved

[0006] In view of the deficiencies of the prior art, the utility model provides a NVP production tubular reactor, which solves the technical problems of low heat transfer efficiency, difficult temperature control and low safety in the traditional NVP synthesis process.

[0007] (II) Technical scheme

[0008] To achieve the above purposes, the utility model realizes the following technical scheme:

[0009] A NVP production tubular reactor, comprising a raw material acetylene gas conveying device and at least one series structure, wherein the series structure comprises a Venturi ejector, a static mixer, a cooler, a tubular reactor and a pressure control tank;

[0010] The inlet of the Venturi ejector is connected with the raw material acetylene gas conveying device and the corresponding pipeline for conveying pressurized 2-pyrrolidone liquid material or NVP crude product respectively, and the outlet is connected with the static mixer; wherein the 2-pyrrolidone liquid material or NVP crude product both contain catalyst pyrrolidone potassium;

[0011] The cooler is connected with the static mixer for cooling the pressurized 2-pyrrolidone liquid material or NVP crude product;

[0012] The tubular reactor is composed of a plurality of tubular reaction units connected in series for carrying out the NVP synthesis reaction of the gas-liquid mixture delivered from the cooler;

[0013] The pressure control tank is used for controlling the pressure of the NVP crude product generated by the reaction and is connected with the next-stage Venturi ejector in series.

[0014] Preferably, the NVP production tubular reactor comprises a three-stage series structure.

[0015] Preferably, the series structure further comprises a 2-P metering pump and a 2-P pressure control tank;

[0016] The 2-P metering pump is used for pressurizing the 2-pyrrolidone liquid material once and pumping it to the 2-P pressure control tank, which is used for controlling the pressure of the 2-pyrrolidone liquid material and is connected with the inlet of the Venturi ejector through a pipeline.

[0017] Preferably, the series structure further comprises an inlet buffer tank, a metering pump and a preheater;

[0018] The inlet of the inlet buffer tank is connected with the cooler, and the top thereof is connected with the raw material acetylene gas delivery device;

[0019] The metering pump is connected with the outlet of the inlet buffer tank and is used for pressurizing the 2-pyrrolidone liquid material or NVP crude product twice and pumping it to the preheater;

[0020] The preheater is used for steam preheating the 2-pyrrolidone liquid material or NVP crude product pressurized twice and is connected with the inlet of the tubular reactor.

[0021] Preferably, the series structure further comprises a product cooler;

[0022] The product cooler is connected with the outlet of the tubular reactor and is used for cooling the NVP crude product generated by the reaction and is connected with the pressure control tank.

[0023] Preferably, the raw material acetylene gas delivery device comprises a raw material acetylene gas main pipe, a compressor, a high-pressure acetylene circulating gas pipe, an inlet cooler and a low-pressure acetylene circulating gas pipe;

[0024] The acetylene gas from the raw material acetylene gas main pipe is partially pressurized by the compressor to the high-pressure acetylene circulating gas pipe and is connected with the inlet of the Venturi ejector, and the other part is cooled by the inlet cooler and is depressurized to the low-pressure acetylene circulating gas pipe and is circulated with the compressor.

[0025] Preferably, the NVP production tubular reactor further comprises a crude product tank, and the pressure control tank of the last stage of the series structure is connected to the crude product tank.

[0026] (III) Beneficial Effects

[0027] The utility model provides a kind of NVP production tubular reactor. Compared with prior art, it has the following beneficial effects:

[0028] In each stage of the series structure, the Venturi ejector generates negative pressure, which sucks in acetylene gas and 2-pyrrolidone liquid material or NVP crude liquid for preliminary mixing, and the static mixer is used for further mixing gas and liquid to form a uniform mixture for cooling in the cooler. The high-pressure and low-temperature conditions improve the solubility of acetylene. Then, the tubular reactor composed of multiple series-connected tubular reaction units is used for gas-liquid two-phase reaction, the residence time of the reaction is accurately controlled, the shell-side heat transfer oil is circulated for heating, which facilitates accurate control of the reaction temperature, and the pressure control tank is used to accurately control the liquid phase pressure of the next stage of the series structure. Moreover, the multi-stage series structure overcomes the disadvantage of difficult control of reaction heat, increases the gas-liquid contact time, and significantly improves the reaction conversion rate and selectivity of NVP by optimizing gas distribution. BRIEF DESCRIPTION OF DRAWINGS

[0029] To more clearly illustrate the technical solutions in the embodiments of the present utility model or the prior art, the drawings needed in the embodiment or prior art description will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present utility model, and other drawings can be obtained by those skilled in the art without creative labor.

[0030] Figure 1 A process schematic diagram of a NVP production tubular reactor provided by the embodiments of the present utility model;

[0031] Figure 2 An equipment structure schematic diagram of a tubular reactor provided by the embodiments of the present utility model;

[0032] Figure 3 A Figure 2 plan view of the A-A' side in

[0033] Figure 4 A Figure 2 plan view of the B-B' side in

[0034] Figure 5 A Figure 2 partial sectional view of C in

[0035] Figure 6 A process schematic diagram of a NVP production tubular reactor based onFigure 1 The production process flow chart of the NVP production tubular reactor is shown.

[0036] Wherein, 10, raw material acetylene gas main pipe; 01, compressor; 08, high-pressure acetylene circulating gas pipe; 02, inlet cooler; 09, low-pressure acetylene circulating gas pipe; 03, 2-P metering pump; 04, 2-P pressure control tank; 20, 2-P stirred tank; 11, 1# venturi ejector; 12, 1# static mixer; 13, 1# inlet buffer tank; 14, 1# metering pump; 15, 1# preheater; 16, 1# reactor; 17, 1# product cooler; 18, 1# pressure control tank; 19, 1# cooler; 21, 2# venturi ejector; 22, 2# static mixer; 23, 2# inlet buffer tank; 24, 2# metering pump; 25, 2# preheater; 26, 2# reactor; 27, 2# product cooler; 28, 2# pressure control tank; 29, 2# cooler; 31, 3# venturi ejector; 32, 3# static mixer; 33, 3# inlet buffer tank; 34, 3# metering pump; 35, 3# preheater; 36, 3# reactor; 37, 3# product cooler; 38, 3# pressure control tank; 39, crude product tank; 40, 3# cooler; 41, rectification device; 100, material inlet; 200, hot oil inlet; 300, oil outlet; 400, material outlet; 500, hot oil outlet; 600, exhaust port; 700, temperature measuring port; 800, pressure measuring port. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical scheme and advantages of the embodiments of the utility model clearer, the technical scheme in the embodiments of the utility model is described clearly and completely, obviously, the described embodiments are part of the embodiments of the utility model, not all the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by the person skilled in the art without creative labor belong to the scope of protection of the utility model.

[0038] The embodiments of the present application provide an NVP production tubular reactor, which solves the technical problems of low heat transfer efficiency, difficult temperature control and low safety in the traditional NVP synthesis process, and improves the reaction conversion rate, selectivity and safety.

[0039] The technical scheme in the embodiments of the present application is as follows to solve the above technical problems:

[0040] The reactor provided by the embodiment of the utility model adopts a multi-stage series connection structure, and each stage of the reactor is composed of a plurality of series connected tubular reaction units. The inner diameter of each reaction unit is moderate (15-50 mm), which can not only ensure good heat transfer efficiency, but also effectively prevent blockage. Compared with a bubble reactor (diameter 300-750 mm) and a micro reactor (diameter < 1 mm), the reactor has at least the following significant technical advantages:

[0041] 1. High heat transfer efficiency: The multi-stage series connection structure increases the total heat transfer area, and the tubular reactor design ensures good heat transfer efficiency, which is especially suitable for severe exothermic reactions, can effectively avoid heat accumulation, reduce side reactions, and improve product selectivity.

[0042] 2. Precision of temperature control: The parameters of the cooling medium can be independently adjusted for each reaction unit, thereby realizing precise temperature control. This helps to ensure the quality of the raw materials during the reaction process, thereby improving the purity of the product.

[0043] 3. Uniform mixing of materials: The tubular design promotes the thorough mixing of materials, which is beneficial to improve the reaction conversion rate and obtain high-quality products.

[0044] 4. High safety: The multi-stage series connection structure design facilitates the control of the reaction process, reducing the risk of reaction runaway.

[0045] 5. Wide application range: The number and arrangement of the reaction units can be adjusted according to different reaction requirements, which is suitable for various gas-liquid two-phase reactions.

[0046] 6. Low operating cost: The reactor adopts a modular design, which is convenient for maintenance and replacement, thereby reducing the operating cost.

[0047] In summary, the tubular reactor performs outstandingly in heat transfer, temperature uniformity, control precision, and industrial application adaptability, and is suitable for reactions with large heat effects. The reactor should be selected according to the reaction characteristics, material properties, and production scale to achieve the best results and economic benefits. The embodiment of the utility model adopts a Venturi ejector and a multi-stage series connection reactor, effectively solving the problem of difficult control of reaction heat in the prior art, while improving the gas-liquid contact time, optimizing the gas distribution, and significantly improving the production efficiency and product quality of NVP.

[0048] In order to better understand the above technical solutions, the above technical solutions will be described in detail in combination with the drawings of the specification and specific embodiments.

[0049] In a first aspect, the embodiment of the utility model provides a tubular reactor for NVP production, which comprises a raw material acetylene gas conveying device and at least one series connection structure, wherein the series connection structure comprises a Venturi ejector, a static mixer, a cooler, a tubular reactor and a pressure control tank.

[0050] The inlets of the Venturi ejectors are connected to the raw acetylene gas delivery device and the corresponding pipeline for delivering the pressurized 2-pyrrolidone liquid material or NVP crude product, respectively, and the outlets are connected to the static mixers; wherein the 2-pyrrolidone liquid material or NVP crude product both contain the catalyst potassium pyrrolidone.

[0051] The cooler is connected to the static mixer for cooling the pressurized 2-pyrrolidone liquid material or NVP crude product.

[0052] The tubular reactor is composed of a plurality of serially connected tubular reaction units for performing the NVP synthesis reaction of the gas-liquid mixture delivered by the cooler.

[0053] The pressure control tank is used for controlling the pressure of the NVP crude product generated by the reaction and is connected to the next-stage serially connected Venturi ejector.

[0054] It should be noted that the throat diameter of the Venturi ejector can be adjusted to adapt to different gas and liquid flow rates for generating negative pressure to suck in the reaction gas and mix with the liquid; the static mixer is used for further mixing the gas and liquid to form a uniform mixture; the tubular reactor is used for performing the gas-liquid two-phase reaction, and the jacket therein circulates heating conduction oil to accurately control the reaction temperature; and the pressure control tank is used for controlling the liquid phase pressure of the next-stage serially connected structure.

[0055] For example, the tubular reactor is made of corrosion-resistant and high-temperature-resistant material, preferably stainless steel material S31603, and has an inner diameter of less than or equal to 50 mm, preferably 32 mm, and a length of 200-400 m, preferably 250-350 m.

[0056] As shown in Figures 2 to 5 , an exemplary structure of a tubular reactor is provided. Referring to Figure 2 , the main structural features are as follows:

[0057] The reactor adopts a shell-and-tube structure design, wherein the tube side is composed of a series of parallelly arranged and closely connected tubes, which are mainly responsible for transporting the reaction materials;

[0058] The shell side is composed of the outer part of the parallel tubes, and the circulation mode of low-in and high-out of the conduction oil is used to achieve efficient heat conduction of the reaction heat; the shell side is provided with baffles, which change the fluid flow path and enhance the turbulent effect, thereby improving the heat transfer efficiency and ensuring the uniformity of the temperature distribution;

[0059] Temperature measuring points and pressure gauges are arranged at the front, middle and rear sections of the reactor, and these devices are used for accurately controlling the reaction conditions;

[0060] In terms of material selection, the reactor body is made of stainless steel S31603, which has excellent corrosion resistance and mechanical strength, and is particularly suitable for use in corrosive environments;

[0061] The structural features and applications of the reactor show that it has a simple structure and a convenient manufacturing process, and is suitable for large-scale and continuous chemical production processes, especially for chemical reactions with significant thermal effects.

[0062] In an optional embodiment, the series structure further comprises a 2-P metering pump and a 2-P pressure control tank.

[0063] The 2-P metering pump is used to pressurize the 2-pyrrolidone liquid material once and pump it to the 2-P pressure control tank, which is used to control the pressure of the 2-pyrrolidone liquid material and is connected to the inlet of the Venturi ejector through a pipeline.

[0064] It should be noted that the 2-P pressure control tank is used to control the liquid phase pressure of the first stage series structure.

[0065] In an optional embodiment, the raw material acetylene gas delivery device comprises a raw material acetylene gas main pipe, a compressor, a high-pressure acetylene circulating gas pipe, an inlet cooler, and a low-pressure acetylene circulating gas pipe.

[0066] The acetylene gas from the raw material acetylene gas main pipe is partially pressurized by the compressor to the high-pressure acetylene circulating gas pipe and connected to the inlet of the Venturi ejector; the other part is cooled by the inlet cooler ， and is depressurized to the low-pressure acetylene circulating gas pipe and circulates with the compressor.

[0067] It should be noted that, based on the pressure control tank / 2-P pressure control tank pressure for controlling the liquid phase pressure of the tank, the compressor and the inlet cooler are used to control the gas phase pressure, ensuring the pressure difference between the gas and liquid phases (e.g., the liquid pressure is higher than the gas pressure by 0.5-2.5 MPa), to achieve the Venturi effect negative pressure absorption of gas to participate in the reaction.

[0068] In an optional embodiment, the series structure further comprises an inlet buffer tank, a metering pump, and a preheater.

[0069] The inlet of the inlet buffer tank is connected to the cooler, and the top is connected to the raw material acetylene gas delivery device.

[0070] The metering pump is connected to the outlet of the inlet buffer tank and is used to pressurize the 2-pyrrolidone liquid material or NVP crude product twice and pump it to the preheater.

[0071] The preheater is used to steam preheat the 2-pyrrolidone liquid material or NVP crude product after secondary pressurization and is connected to the inlet of the tubular reactor.

[0072] It should be noted that the metering pump is used to accurately control the flow and pressure of the reaction liquid, and is preferably a diaphragm metering pump to improve the accuracy of pressure control; the inlet buffer tank is used to stabilize the reaction pressure and ensure the stability of the reaction process; and the preheater is a high-efficiency heat exchanger used for rapid temperature adjustment.

[0073] In an alternative embodiment, the series structure further comprises a product cooler;

[0074] The product cooler is connected to the outlet of the tubular reactor for cooling the NVP crude product generated by the reaction, and is connected to the pressure control tank.

[0075] It should be noted that the product cooler is a high-efficiency heat exchanger used for rapid temperature adjustment.

[0076] In an alternative embodiment, the NVP production tubular reactor further comprises a crude product tank, and the pressure control tank of the last stage of the series structure is connected to the crude product tank.

[0077] In fact, the reactor provided in the embodiments of the present application can be used in one or more stages in series, preferably three stages in series to obtain a higher conversion rate, as shown in the following table: Figure 1

[0078] The raw material acetylene gas delivery device comprises a raw material acetylene gas main pipe 10, a compressor 01, a high-pressure acetylene circulating gas pipe 08, an inlet cooler 02, and a low-pressure acetylene circulating gas pipe 09.

[0079] The acetylene gas from the raw material acetylene gas main pipe 10 is partially pressurized to 1.4-1.5 Mpa by the compressor 01 and connected to the inlet of the 1# Venturi ejector 11 through the high-pressure acetylene circulating gas pipe 08, and the other part (i.e., acetylene gas not participating in the reaction) is cooled by the inlet cooler 02 and then reduced to 0.05 Mpa by the pressure control valve and connected to the compressor 01 through the low-pressure acetylene circulating gas pipe 09.

[0080] Considering that the components of each stage of the series structure are basically the same, only the first stage of the series structure will be described in detail below:

[0081] The 2-P metering pump 03 is used to pressurize the 2-pyrrolidone liquid material once and pump it to the 2-P pressure control tank 04, and the 2-P pressure control tank 04 is used to control the pressure of the 2-pyrrolidone liquid material and connected to the inlet of the 1# Venturi ejector 1 through a pipeline.

[0082] ​The inlet of Venturi injector 11 is connected to the high-pressure acetylene circulating gas pipe 08 of the raw material acetylene gas conveying device and the corresponding pipeline for conveying pressurized 2-pyrrolidone liquid material, and the outlet is connected to static mixer 12. The 2-pyrrolidone liquid material contains potassium pyrrolidone catalyst.

[0083] It should be noted that, unlike this, both the #2 Venturi injector 21 and the #3 Venturi injector 31 are connected to the pipeline that transports the pressurized NVP crude product; the NVP crude product also contains the catalyst potassium pyrrolidone.

[0084] Cooler 19 is connected to static mixer 12 and is used to cool pressurized 2-pyrrolidone liquid material.

[0085] The inlet of the No. 1# inlet buffer tank 13 is connected to the No. 1# cooler 19, and the top is connected to the high-pressure acetylene circulating gas pipe 08 of the raw material acetylene gas conveying device.

[0086] The outlet of metering pump 14 is connected to the outlet of inlet buffer tank 13 to pressurize 2-pyrrolidone liquid material for a second time and pump it to preheater 15.

[0087] Preheater 15 is used to preheat the 2-pyrrolidone liquid material after secondary pressurization with steam to 100-130°C, and is connected to the inlet of tubular reactor 16.

[0088] It should be noted that, unlike this, metering pump 24 and metering pump 34 are used for secondary pressurization of NVP crude product, and preheater 25 and preheater 35 are used for steam preheating of the secondary pressurized NVP crude product to 100-130℃.

[0089] The No. 1 tubular reactor 16 consists of multiple tubular reaction units connected in series, used for the NVP synthesis reaction of the gas-liquid mixture delivered by the No. 1 static mixer 12.

[0090] Product cooler 17 is connected to the outlet of tubular reactor 16 to cool the crude NVP product generated by the reaction to 20-50°C, and is connected to pressure control tank 18.

[0091] Pressure control tank 18 is used to control the pressure of the NVP crude product generated by the reaction at 3.5-4.5 MPa. It is connected to the next stage cascaded Venturi ejector (i.e., Venturi ejector 21). This is different from the last three-stage cascaded pressure control tank (i.e., pressure control tank 38) which is connected to the crude product tank 39.

[0092] Secondly, such as Figure 6The utility model embodiment provides a kind of production process based on the NVP production tubular reactor above, it include:

[0093] S1, raw material acetylene gas nitrogen mixed gas is compressed to pressure 1.3~1.8Mpa by compressor 01, is decompressed to flow 20~60m 3 / h by import cooler 02 circulation;Wherein acetylene volume ratio in mixed gas is 45%~55%.

[0094] S2, raw material 2-P is added to preparation kettle, and then solid potassium hydroxide is added to carry out dissolution reaction and vacuum water removal, and qualified pyrrolidone potassium liquid is placed to 2-P stirred tank 20, is pumped into 2-P pressure control tank by 2-P metering pump, and pressure control is 3.5~4.5Mpa;Wherein pyrrolidone potassium liquid material contains 2-pyrrolidone with mass fraction 98%~99.5% and 0.5%~2% pyrrolidone potassium.

[0095] S3, at the first stage of series structure:

[0096] 2-P flow of 2-P pressure control tank 04 bottom is controlled to 280~320L / h, and acetylene gas nitrogen mixed gas sent by high-pressure acetylene circulating gas pipe 08 is mixed, is mixed by 1# venturi injector 11 and 1# static mixer 12, is cooled after 1# cooler 19, and then enters 1# import buffer tank 13, and pressure keeps 1.5~2.5Mpa, and the top of 1# import buffer tank 13 is analyzed gas and returns to high-pressure acetylene circulating gas pipe 08, and is replaced to flare by periodical displacement;

[0097] by 1# metering pump 14 to 3.5~4.5MpaMpa and is pumped into 1# preheater 15, and steam is preheated to 100~130 DEG C and enters 1# tubular reactor 16, and reaction temperature is 160~180 DEG C, and reaction pressure is 3.5~4.5Mpa;

[0098] After reaction, enter 1# product cooler 17, and cool to 30~45 DEG C, and then enter 1# pressure control tank 18, and pressure is stabilized at 3.5~4.5Mpa, and enter the second stage of series structure.

[0099] S4, at the second stage of series structure:

[0100] The NVP crude product flow rate from the bottom of the 1# pressure control tank 18 is controlled at 280-320 L / h, and mixed with the acetylene-nitrogen mixed gas from the high-pressure acetylene circulating gas pipe 08, and then gas-liquid mixed by the 2# venturi injector 21 and the 2# static mixer 22, cooled by the 2# cooler, and then enters the 2# inlet buffer tank 23, with the pressure maintained at 1.5-2.5 MPa, and the top of the 2# inlet buffer tank 23 is purged into the high-pressure acetylene circulating gas pipe 08, and periodically replaced and vented to the flare;

[0101] The 2# metering pump 24 is pressurized to 3.5-4.5 MPa and pumped into the 2# preheater 25, and the steam is preheated to 100-130℃ and enters the 2# tubular reactor 26, with the reaction temperature being 160-180℃ and the reaction pressure being 3.5-4.5 MPa;

[0102] After the reaction, it enters the 2# product cooler 27, is cooled to 30-45℃, and then enters the 2# pressure control tank 28, with the pressure stabilized at 3.5-4.5 MPa, and enters the third-stage series structure.

[0103] S5, at the third-stage series structure:

[0104] The NVP crude product flow rate from the bottom of the 2# pressure control tank 28 is controlled at 280-320 L / h, and mixed with the acetylene-nitrogen mixed gas from the high-pressure acetylene circulating gas pipe 08, and then gas-liquid mixed by the 3# venturi injector 31 and the 3# static mixer 32, cooled by the 3# cooler 40, and then enters the 3# inlet buffer tank 33, with the pressure maintained at 1.5-2.5 MPa, and the top of the 3# inlet buffer tank 33 is purged into the high-pressure acetylene circulating gas pipe 08, and periodically replaced and vented to the flare;

[0105] The 3# metering pump 34 is pressurized to 3.5-4.5 MPa and pumped into the 3# preheater 35, and the steam is preheated to 100-130℃ and enters the 3# tubular reactor 36, with the reaction temperature being 160-180℃ and the reaction pressure being 3.5-4.5 MPa;

[0106] After the reaction, it enters the 3# product cooler 37, is cooled to 30-45℃, and then enters the 3# pressure control tank 38, with the pressure stabilized at 3.5-4.5 MPa, and the bottom of the 3# pressure control tank 38 is depressurized to normal pressure and enters the crude product tank 39, and finally enters the rectification device 41 for purification into a fine product.

[0107] In an optional embodiment, the S1 is compressed by the compressor 01 to a pressure of 1.4-1.6 MPa.

[0108] In an alternative embodiment, the 1# cooler 19 in S3 is cooled to less than 40℃ and enters the 1# inlet buffer tank 13, the pressure at the 1# pressure control tank 18 is 3.8-4.3 MPa; the 2# cooler 29 in S4 is cooled to less than 40℃ and enters the 2# inlet buffer tank 23, the pressure at the 2# pressure control tank 28 is 3.8-4.3 MPa; the 3# cooler 40 in S5 is cooled to less than 40℃ and enters the 3# inlet buffer tank 33, the pressure at the 3# pressure control tank 38 is 3.8-4.3 MPa.

[0109] In an alternative embodiment, in order to generate a Venturi effect negative pressure to absorb the gas involved in the reaction, the 2-P pressure at the inlet of the 1# Venturi ejector 11 in S3 is higher than the acetylene gas-nitrogen gas mixture pressure by 0.5-2.5 MPa, preferably 1.0-1.5 MPa.

[0110] Similarly, the NVP crude pressure at the inlet of the 2# Venturi ejector 21 in S4 is higher than the acetylene gas-nitrogen gas mixture pressure by 0.5-2.5 MPa, preferably 1.0-1.5 MPa.

[0111] In order to better understand the NVP production tubular reactor provided by the embodiments of the present application, the following specific comparative experiments are provided:

[0112] Comparative Example:

[0113] A traditional bubble reactor is used, and the experimental parameters are as follows: the a~P flow rate is set to 300 L / h; the acetylene flow rate is 30 m 3 / h; the reaction pressure is maintained in the range of 1.4-1.5 MPa; and the reaction temperature is controlled in the range of 140-160℃.

[0114] Example 1:

[0115] A novel reactor provided by the embodiments of the present application is used, and the experimental parameters are as follows: the 2~P flow rate / NVP crude flow rate is 300 L / h, the acetylene flow rate is 30 m 3 / h, the reaction pressure is between 3.5-4.5 MPa, and the reaction temperature is 160-180℃.

[0116] Example 2:

[0117] A novel reactor provided by the embodiments of the present application is used, and the experimental parameters are as follows: the 2~P flow rate / NVP crude flow rate is increased to 310 L / h, the acetylene flow rate is increased to 32 m 3 / h, the reaction pressure is also 3.5-4.5 MPa, and the reaction temperature is 160-180℃.

[0118] Example 3:

[0119] The novel reactor provided by the embodiment of the utility model, experimental parameters: 2~P flow rate / NVP crude product flow rate is reduced to 290L / h, acetylene flow rate is reduced to 28m 3 / h, reaction pressure is kept 3.5~4.5Mpa, reaction temperature is 160~180 DEG C.

[0120] Experimental results comparison

[0121] 1.NVP content in crude product

[0122] The NVP content in the crude product obtained by the traditional bubble reactor is only 42%.

[0123] The novel reactor shows higher NVP content under different embodiments, reaches 65% in embodiment 1, reaches 68% in embodiment 2, reaches 66% in embodiment 3, and the average content is about 66.2%, which is increased by about 57.6% compared with the traditional bubble reactor.

[0124] That is, by optimizing the combination of conditions such as increasing reaction pressure and temperature, the novel reactor greatly improves the NVP content in the crude product. Compared with the traditional bubble reactor, the average content is increased by 57.6%, which means that under the same raw material input, the novel reactor can produce more NVP products, significantly improving production efficiency and product yield.

[0125] 2.NVP synthesis reaction selectivity

[0126] The NVP synthesis reaction selectivity of the traditional bubble reactor is 90%.

[0127] The NVP synthesis reaction selectivity of the novel reactor in embodiment 1 is 94.1%, in embodiment 2 is 95.2%, in embodiment 3 is 95.8%, and the average selectivity is about 95.03%, which is increased by about 5.03% compared with the traditional bubble reactor.

[0128] That is, the novel reactor also has obvious progress in NVP synthesis reaction selectivity, and the average selectivity is increased by about 5.58%. This shows that in the reaction process, the novel reactor can more accurately promote 2-P to react with acetylene to generate NVP, reduce the occurrence of side reactions, and is beneficial to improve product purity and reduce subsequent separation and purification cost.

[0129] In addition, it can be seen from the experimental data that the NVP content and NVP selectivity of the crude product in the new reactor have less fluctuation in different embodiments. For example, the NVP content fluctuates between 65% and 68%, and the NVP selectivity fluctuates between 94.1% and 95.8%, while the conventional bubble reactor may have a larger fluctuation in product quality due to the limitation of its own structure and reaction conditions, and the slight changes in temperature, pressure and other factors during the reaction. The stability advantage of the new reactor makes it more suitable for long-term and large-scale industrial production applications, and can ensure the consistency and stability of product quality.

[0130] In summary, the experimental results show that the reactor provided in the embodiments of the present application improves the synthesis efficiency of NVP, and the crude product content is increased from 40% to 45% to 55% to 75%, which is more than 10% to 30% higher than the prior art, and the selectivity reaches more than 94%, which is significantly better than the prior art.

[0131] It should be noted that in this paper, relational terms such as first and second are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that there is any such actual relationship or order between these entities or operations. Moreover, the terms "include", "contain" or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, method, article or equipment including a series of elements not only includes those elements, but also includes other elements not explicitly listed or inherent to such process, method, article or equipment. Without more limitations, the element defined by the statement "including a" does not exclude the presence of another identical element in the process, method, article or equipment including the element.

[0132] The above embodiments are only used to illustrate the technical solutions of the present application, but not to limit it; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A tubular reactor for NVP production, characterized in that, It includes a raw material acetylene gas conveying device and at least one series structure, wherein the series structure includes a Venturi injector, a static mixer, a cooler, a tubular reactor, and a pressure control tank. The inlet of the Venturi injector is connected to the raw material acetylene gas conveying device and the corresponding pipeline for conveying pressurized 2-pyrrolidone liquid material or NVP crude product, and the outlet is connected to the static mixer; wherein the 2-pyrrolidone liquid material or NVP crude product contains the catalyst potassium pyrrolidone. The cooler is connected to the static mixer and is used to cool the pressurized 2-pyrrolidone liquid material or NVP crude product; The tubular reactor consists of multiple tubular reaction units connected in series, used for NVP synthesis reaction of a gas-liquid mixture supplied by a cooler. The pressure control tank is used to control the pressure of the NVP crude product generated by the reaction and is connected to the Venturi injector in the next stage series structure.

2. The NVP production tubular reactor as described in claim 1, characterized in that, The NVP production tubular reactor comprises a three-stage series structure.

3. The NVP production tubular reactor as described in claim 1, characterized in that, The series structure also includes a 2-P metering pump and a 2-P pressure control tank; The 2-P metering pump is used to pressurize 2-pyrrolidone liquid material once and pump it to the 2-P pressure control tank. The 2-P pressure control tank is used to control the pressure of 2-pyrrolidone liquid material and is connected to the inlet of the Venturi injector through a pipeline.

4. The NVP production tubular reactor as described in claim 1, characterized in that, The series structure also includes an inlet buffer tank, a metering pump, and a preheater; The inlet of the imported buffer tank is connected to the cooler, and the top is connected to the raw material acetylene gas conveying device. The metering pump is connected to the outlet of the inlet buffer tank for secondary pressurization of 2-pyrrolidone liquid material or NVP crude product, and pumps it to the preheater. The preheater is used to preheat the 2-pyrrolidone liquid material or NVP crude product after secondary pressurization with steam, and is connected to the inlet of the tubular reactor.

5. The NVP production tubular reactor as described in claim 1, characterized in that, The series structure also includes a product cooler; The product cooler is connected to the outlet of the tubular reactor to cool the crude NVP produced by the reaction, and is also connected to the pressure control tank.

6. The NVP production tubular reactor as described in claim 1, characterized in that, The raw material acetylene gas conveying device includes a raw material acetylene gas main pipe, a compressor, a high-pressure acetylene circulating gas pipe, an inlet cooler, and a low-pressure acetylene circulating gas pipe. The acetylene gas from the main acetylene gas pipeline is partially pressurized by the compressor and sent to the high-pressure acetylene recirculation pipeline, which is connected to the inlet of the Venturi injector; the other part is cooled by the inlet cooler and then depressurized to the low-pressure acetylene recirculation pipeline, where it circulates with the compressor.

7. The NVP production tubular reactor as described in claim 1, characterized in that, The NVP production tubular reactor also includes a crude product tank, and the final stage of the series-connected pressure control tank is connected to the crude product tank.

Images