NVP production tubular reactor and production process

Abstract

The invention provides an NVP production tubular reactor and a production process, and relates to the technical field of chemical and pharmaceutical 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 series connection of multiple stages of tubular reactors, meanwhile, the reaction temperature and pressure are accurately controlled, and the production safety is ensured. Experimental results show that the synthesis efficiency and the product quality of the NVP are remarkably improved.

Description

Technical Field

[0001] The invention relates to the technical field of chemical and pharmaceutical industries, and in particular to a NVP production tubular reactor and a production process. Background Art

[0002] N-vinylpyrrolidone (NVP) is an important chemical and pharmaceutical intermediate, widely used in medicine, cosmetics, coatings, adhesives and other fields.

[0003] At present, the production process of NVP is mainly based on the acetylene method. The acetylene method uses acetylene and 2-pyrrolidone (2-Pyrrolidone, hereinafter referred to as 2-P) as raw materials, and performs an addition reaction under the action of a catalyst (potassium 2-pyrrolidone) to produce NVP. However, in the production process of NVP, the gas-liquid two-phase reaction is a key link and also a technical difficulty.

[0004] In the related technology, the gas-liquid two-phase countercurrent bubbling reactor has obvious shortcomings in the NVP synthesis process. Due to the violent release of reaction heat, the temperature is difficult to control stably; the gas-liquid contact time is short, which affects the reaction conversion rate; the reactor has a large aspect ratio, which leads to increased backmixing, making subsequent distillation separation difficult. In addition, the NVP synthesis reaction also has difficulties such as unstable activity of potassium pyrrolidone, low solubility of acetylene, and flammability and explosion. Summary of the invention

[0005] 1. Technical issues to be resolved

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

[0007] (II) Technical solution

[0008] To achieve the above objectives, the present invention is implemented through the following technical solutions:

[0009] A tubular reactor for NVP production, comprising a raw material acetylene gas conveying device and at least one stage of 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 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;

[0011] The cooler is connected to the static mixer and is used to cool 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 and is used for carrying out the NVP synthesis reaction of the gas-liquid mixture transported by the cooler;

[0013] 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 ejector of the next stage series structure.

[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 to pressurize the 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 the 2-pyrrolidone liquid material and is connected to the inlet of the venturi injector 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 to the cooler, and the top is connected to the raw material acetylene gas conveying device;

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

[0020] The preheater is used to steam preheat the secondary pressurized 2-pyrrolidone liquid material or NVP crude product, and is connected to the inlet of the tubular reactor.

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

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

[0023] Preferably, the raw material acetylene gas conveying 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] Part of the acetylene gas from the raw acetylene gas main is pressurized by the compressor to the high-pressure acetylene circulation gas pipe and connected to the inlet of the Venturi injector; the other part is cooled by the inlet cooler, decompressed to the low-pressure acetylene circulation gas pipe, and 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] A production process for producing a tubular reactor based on NVP as described above, characterized in that it comprises:

[0027] S1. The raw material acetylene gas and nitrogen mixed gas is compressed to a pressure of 1.3-1.8Mpa by a compressor, and then decompressed and circulated to a flow rate of 20-60m3 by an imported cooler. 3 / h; the volume proportion of acetylene in the mixed gas is 45% to 55%;

[0028] S2, adding raw material 2-P to a preparation kettle, adding solid potassium hydroxide to dissolve and remove water in vacuo, preparing a qualified potassium pyrrolidone liquid and putting it into a 2-P stirring kettle, and pumping it into a 2-P pressure control tank through a 2-P metering pump, and the pressure is controlled at 3.5-4.5Mpa; wherein the potassium pyrrolidone liquid material contains 2-pyrrolidone with a mass fraction of 98%-99.5% and potassium pyrrolidone with a mass fraction of 0.5%-2%;

[0029] S3, at the first stage of the series structure:

[0030] The 2-P flow rate delivered from the bottom of the 2-P pressure control tank is controlled to be 280-320L / h. The mixed gas with acetylene gas and nitrogen delivered from the high-pressure acetylene circulating gas pipe is mixed with gas and liquid in the 1# Venturi ejector and the 1# static mixer and cooled in the 1# cooler before entering the 1# inlet buffer tank. The pressure is maintained at 1.5-2.5Mpa. The decomposed gas at the top of the 1# inlet buffer tank returns to the high-pressure acetylene circulating gas pipe and is regularly replaced and vented to the flare.

[0031] The 1# metering pump pressurizes the steam to 3.5-4.5Mpa and pumps it into the 1# preheater. The steam is preheated to 100-130°C and enters the 1# tubular reactor. The reaction temperature is 160-180°C and the reaction pressure is 3.5-4.5Mpa.

[0032] After the reaction, it enters the 1# product cooler, cools to 30-45°C, and then enters the 1# pressure control tank, where the pressure is stabilized at 3.5-4.5Mpa, and enters the secondary series structure;

[0033] S4, at the second-stage series structure:

[0034] The crude NVP product flow rate from the bottom of the 1# pressure control tank is controlled to be 280-320L / h, and the mixture gas with acetylene gas and nitrogen sent from the high-pressure acetylene circulating gas pipe is mixed with gas and liquid in the 2# Venturi ejector and the 2# static mixer, and then cooled in the 2# cooler before entering the 2# inlet buffer tank. The pressure is maintained at 1.5-2.5Mpa, and the top of the 2# inlet buffer tank is returned to the high-pressure acetylene circulating gas pipe, and is regularly replaced and vented to the torch; the crude NVP product contains 10%-40% NVP by mass and 0.5%-2% of the catalyst potassium pyrrolidone;

[0035] The 2# metering pump pressurizes the steam to 3.5-4.5Mpa and pumps it into the 2# preheater. The steam is preheated to 100-130°C and enters the 2# tubular reactor. The reaction temperature is 160-180°C and the reaction pressure is 3.5-4.5Mpa.

[0036] After the reaction, it enters the 2# product cooler, cools to 30-45°C, and then enters the 2# pressure control tank, where the pressure is stabilized at 3.5-4.5Mpa, and enters the three-stage series structure;

[0037] S5. At the third-level series structure:

[0038] The crude NVP product flow rate from the bottom of the 2# pressure control tank is controlled to be 280-320L / h. The crude NVP product is mixed with the acetylene gas and nitrogen from the high-pressure acetylene circulating gas pipe. After being mixed with gas and liquid by the 3# Venturi ejector and the 3# static mixer and cooled by the 3# cooler, it enters the 3# inlet buffer tank. The pressure is maintained at 1.5-2.5Mpa. The decomposed gas at the top of the 3# inlet buffer tank returns to the high-pressure acetylene circulating gas pipe and is regularly replaced and vented to the flare.

[0039] The 3# metering pump pressurizes the steam to 3.5-4.5Mpa and pumps it into the 3# preheater. The steam is preheated to 100-130℃ and enters the 3# tubular reactor. The reaction temperature is 160-180℃ and the reaction pressure is 3.5-4.5Mpa.

[0040] After the reaction, it enters the 3# product cooler, and after being cooled to 30-45°C, it enters the 3# pressure control tank, where the pressure is stabilized at 3.5-4.5Mpa. It then enters the distillation device through the crude product tank to be purified into fine products.

[0041] Preferably, the S1 is compressed to a pressure of 1.4-1.6 MPa by a compressor;

[0042] Preferably, the 1# cooler in S3 cools to less than 40°C and then enters the 1# inlet buffer tank, and the pressure at the 1# pressure control tank is 3.8-4.3Mpa;

[0043] The 2# cooler in S4 cools to less than 40°C and then enters the 2# inlet buffer tank, and the pressure at the 2# pressure control tank is 3.8-4.3Mpa;

[0044] After the 3# cooler in S5 cools to less than 40°C, it enters the 3# inlet buffer tank, and the pressure at the 3# pressure control tank is 3.8-4.3Mpa.

[0045] Preferably, the 2-P pressure at the inlet of the 1# Venturi injector in S3 is 0.5 to 2.5 MPa higher than the pressure of the acetylene gas and nitrogen mixed gas;

[0046] The NVP crude product pressure at the inlet of the 2# Venturi injector in S4 is 0.5-2.5 MPa higher than the pressure of the acetylene gas and nitrogen mixed gas;

[0047] The NVP crude product pressure at the inlet of the 3# Venturi injector in S5 is 0.5 to 2.5 MPa higher than the pressure of the acetylene gas and nitrogen mixed gas.

[0048] (III) Beneficial effects

[0049] The present invention provides a tubular reactor and a production process for NVP production. Compared with the prior art, the present invention has the following beneficial effects:

[0050] The present invention uses a venturi ejector to generate negative pressure in each stage of the series structure, sucks acetylene gas and 2-pyrrolidone liquid material or NVP crude liquid for preliminary mixing, uses a static mixer to further mix the gas and liquid to form a uniform mixture and send it to a cooler for cooling, and improves the solubility of acetylene through high pressure and low temperature conditions; then uses a tubular reactor composed of multiple series-connected tubular reaction units to carry out gas-liquid two-phase reaction, accurately controls the reaction residence time, and heats the shell side heat transfer oil in a circulating manner, which is convenient for accurately controlling the reaction temperature; and uses a pressure control tank to accurately control the liquid phase pressure of the next stage of the series structure. In addition, the designed multi-stage series structure overcomes the disadvantage that the reaction heat is difficult to control, while increasing the gas-liquid contact time, and significantly improves the reaction conversion rate and selectivity of NVP by optimizing the gas distribution. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0052] Figure 1 A schematic diagram of a process flow of a NVP production tubular reactor provided in an embodiment of the present invention;

[0053] Figure 2 A schematic diagram of the equipment structure of a tubular reactor provided in an embodiment of the present invention;

[0054] Figure 3 for Figure 2 The plan view of the A-A' side;

[0055] Figure 4 for Figure 2 The plan view of the B-B' side;

[0056] Figure 5 for Figure 2 Partial cross-section at point C in the middle;

[0057] Figure 6 A method based on the embodiment of the present invention is provided Figure 1 The production process flow chart of the NVP production tubular reactor is shown.

[0058] Among them, 10, raw material acetylene gas main pipe; 01, compressor; 08, high-pressure acetylene circulation gas pipe; 02, imported cooler; 09, low-pressure acetylene circulation gas pipe; 03, 2-P metering pump; 04, 2-P pressure control tank; 20, 2-P stirring kettle; 11, 1# Venturi ejector; 12, 1# static mixer; 13, 1# imported 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# imported buffer tank; 24, 2# metering pump; 2 5. 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# import 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. distillation unit; 100. material inlet; 200. hot oil inlet; 300. oil discharge port; 400. material outlet; 500. hot oil outlet; 600. exhaust port; 700. temperature measuring port; 800. pressure measuring port. DETAILED DESCRIPTION

[0059] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are clearly and completely described. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0060] The embodiments of the present application provide a NVP production tubular reactor and a production process, thereby solving the technical problems of low heat transfer efficiency, difficult temperature control, and low safety in the traditional NVP synthesis process, and improving the reaction conversion rate, selectivity, and safety.

[0061] The technical solution in the embodiment of the present application is to solve the above technical problems, and the overall idea is as follows:

[0062] The reactor provided in the embodiment of the present invention adopts a multi-stage series structure, and each stage of the reactor is composed of multiple tubular reaction units connected in series. 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 the bubbling reactor (diameter 300-750 mm) and the microreactor (diameter <1 mm), the reactor has at least the following significant technical advantages:

[0063] 1. High heat transfer efficiency: The multi-stage series structure increases the total heat transfer area, and the tubular reactor design ensures good heat transfer efficiency, which is especially suitable for violent exothermic reactions. It can effectively avoid heat accumulation, reduce side reactions, and improve product selectivity.

[0064] 2. Accuracy of temperature control: Each reaction unit can independently adjust the parameters of the cooling medium to achieve precise temperature control. This helps to ensure the quality of the raw materials during the reaction process and thus improve the purity of the product.

[0065] 3. Even mixing of materials: The tubular design promotes the full mixing of materials, which is beneficial to improving the reaction conversion rate and obtaining high-quality products.

[0066] 4. High safety: The multi-stage series structure design facilitates the control of the reaction process and reduces the risk of reaction runaway.

[0067] 5. Wide range of applications: The number and arrangement of reaction units can be adjusted according to different reaction requirements to adapt to a variety of gas-liquid two-phase reactions.

[0068] 6. Low operating cost: The reactor adopts modular design, which is easy to maintain and replace, reducing operating costs.

[0069] In summary, tubular reactors have outstanding performance in heat transfer, temperature uniformity, control accuracy and adaptability to industrial applications, and are suitable for reactions with large thermal effects. Reactors should be selected based on reaction characteristics, material properties and production scale to achieve optimal effects and economic benefits. The embodiments of the present invention effectively solve the problem of difficult control of reaction heat in the prior art by using a venturi ejector and a multi-stage series reactor, while increasing the gas-liquid contact time, optimizing gas distribution, and significantly improving the production efficiency and product quality of NVP.

[0070] In order to better understand the above technical solution, the above technical solution will be described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0071] In a first aspect, an embodiment of the present invention provides a tubular reactor for NVP production, comprising a raw 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.

[0072] The inlet of the venturi ejector is respectively 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.

[0073] The cooler is connected to the static mixer and is used to cool the pressurized 2-pyrrolidone liquid material or NVP crude product.

[0074] The tubular reactor is composed of a plurality of tubular reaction units connected in series and is used for carrying out NVP synthesis reaction of a gas-liquid mixture transported by a cooler.

[0075] 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 ejector of the next stage series structure.

[0076] It should be noted that the throat diameter of the venturi ejector is adjustable to accommodate different gas and liquid flow rates, and is used to generate negative pressure, inhale the reaction gas and mix it with the liquid; the static mixer is used to further mix the gas and liquid to form a uniform mixture; the tubular reactor is used for gas-liquid two-phase reaction, and the heat transfer oil circulates in its jacket to accurately control the reaction temperature; the pressure control tank is used to control the liquid phase pressure of the next stage of the series structure.

[0077] Exemplarily, the tubular reactor is made of corrosion-resistant and high-temperature-resistant material, preferably stainless steel S31603, and has an inner diameter less than or equal to 50 mm, preferably 32 mm, and a tube length of 200 to 400 m, preferably 250 to 350 m.

[0078] like Figures 2 to 5 As shown, a tubular reactor structure is provided here as an example. Figure 2 , its main structural features are as follows:

[0079] The reactor adopts a shell-and-tube structure design, in which the tube side is composed of a series of tubes arranged in parallel and closely connected end to end, which is mainly responsible for transporting the reaction materials;

[0080] The shell side is composed of parallel tubes, and the heat transfer oil is circulated in a low-in and high-out mode to achieve efficient heat removal of the reaction. The shell side is equipped with baffles, which change the flow path of the fluid, enhance the turbulence effect, thereby improving the heat transfer efficiency and ensuring the uniformity of temperature distribution.

[0081] Temperature measuring points and pressure gauges are set at the front, middle and back sections of the reactor respectively, and these devices are used to accurately control the reaction conditions;

[0082] 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;

[0083] The structural characteristics and applications of this reactor show that it has a simple structure and a convenient manufacturing process, and is suitable for large-scale, continuous chemical production processes, especially for chemical reactions with significant thermal effects.

[0084] In an optional embodiment, the series structure further includes a 2-P metering pump and a 2-P pressure control tank.

[0085] 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. The 2-P pressure control tank is used to control the pressure of the 2-pyrrolidone liquid material and is connected to the inlet of the venturi injector through a pipeline.

[0086] 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.

[0087] In an optional embodiment, the raw material acetylene gas delivery device includes a raw material acetylene gas main pipe, a compressor, a high-pressure acetylene circulation gas pipe, an inlet cooler and a low-pressure acetylene circulation gas pipe;

[0088] Part of the acetylene gas from the raw acetylene gas main is pressurized by the compressor to the high-pressure acetylene circulation gas pipe and connected to the inlet of the Venturi injector; the other part is cooled by the inlet cooler, decompressed to the low-pressure acetylene circulation gas pipe, and circulated with the compressor.

[0089] It should be noted that on the basis that the pressure control tank / 2-P pressure control tank pressure is used to control the liquid phase pressure of the control tank, the compressor and imported cooler are used to control the gas phase pressure to ensure the pressure difference between the gas and liquid phases (for example, the liquid pressure is 0.5~2.5Mpa higher than the gas pressure) to achieve the Venturi effect negative pressure absorption gas to participate in the reaction.

[0090] In an optional embodiment, the series structure further includes an inlet buffer tank, a metering pump and a preheater;

[0091] The inlet of the inlet buffer tank is connected to the cooler, and the top is connected to the raw material acetylene gas conveying device;

[0092] The metering pump is connected to the outlet of the inlet buffer tank and is used for secondary pressurizing the 2-pyrrolidone liquid material or the NVP crude product and pumping it to the preheater;

[0093] The preheater is used to steam preheat the secondary pressurized 2-pyrrolidone liquid material or NVP crude product, and is connected to the inlet of the tubular reactor.

[0094] 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 imported buffer tank is used to stabilize the reaction pressure and ensure the stability of the reaction process; the preheater is a high-efficiency heat exchanger for quickly adjusting the temperature.

[0095] In an optional embodiment, the series structure further includes a product cooler;

[0096] The product cooler is connected to the outlet of the tubular reactor, is used to cool the NVP crude product generated by the reaction, and is connected to the pressure control tank.

[0097] It should be noted that the product cooler is a high-efficiency heat exchanger used to quickly adjust the temperature.

[0098] In an optional embodiment, the NVP production tubular reactor further includes a crude product tank, and the pressure control tank of the last stage of the series structure is connected to the crude product tank.

[0099] In fact, the reactor provided in the embodiment of the present invention can be used in one or more stages in series, preferably three stages in series to obtain a higher conversion rate, such as Figure 1 As shown:

[0100] The raw material acetylene gas conveying 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 .

[0101] A part of the acetylene gas from the raw material acetylene gas main pipe 10 is pressurized to 1.4-1.5Mpa high-pressure acetylene circulation gas pipe 08 by the compressor 01, and connected to the inlet of the 1# Venturi injector 11; the other part (i.e. the acetylene gas that does not participate in the reaction) is cooled by the inlet cooler 02, and then reduced to 0.05Mpa low-pressure acetylene circulation gas pipe 09 by the pressure control valve, and circulated with the compressor 01.

[0102] Considering that the components of each stage of the series structure are basically the same, the following only describes the first stage of the series structure in detail:

[0103] 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. The 2-P pressure control tank 04 is used to control the pressure of the 2-pyrrolidone liquid material and is connected to the inlet of the 1# Venturi injector 1 through a pipeline.

[0104] The inlet of the 1# Venturi ejector 11 is respectively connected to the high-pressure acetylene circulation 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 the 1# static mixer 12; wherein the 2-pyrrolidone liquid material contains the catalyst potassium pyrrolidone.

[0105] It should be noted that, in contrast, both the 2# Venturi ejector 21 and the 3# Venturi ejector 31 are connected to a pipeline for conveying pressurized NVP crude product; wherein the NVP crude product also contains the catalyst potassium pyrrolidone.

[0106] The 1# cooler 19 is connected to the 1# static mixer 12 and is used to cool the pressurized 2-pyrrolidone liquid material.

[0107] The inlet of the 1# inlet buffer tank 13 is connected to the 1# cooler 19, and the top is connected to the high-pressure acetylene circulation gas pipe 08 of the raw material acetylene gas conveying device.

[0108] The 1# metering pump 14 is connected to the outlet of the 1# inlet buffer tank 13 and is used for secondary pressurizing the 2-pyrrolidone liquid material and pumping it to the 1# preheater 15 .

[0109] The 1# preheater 15 is used to steam preheat the 2-pyrrolidone liquid material after secondary pressurization to 100-130° C., and is connected to the inlet of the 1# tubular reactor 16 .

[0110] It should be noted that, in contrast, the 2# metering pump 24 and the 3# metering pump 34 are both used for secondary pressurization of the crude NVP product, and the 2# preheater 25 and the 3# preheater 35 are both used for steam preheating the crude NVP product after secondary pressurization to 100-130°C.

[0111] The 1# tubular reactor 16 is composed of a plurality of tubular reaction units connected in series and is used for carrying out the NVP synthesis reaction of the gas-liquid mixture transported by the 1# static mixer 12 .

[0112] The 1# product cooler 17 is connected to the outlet of the 1# tubular reactor 16 and is used to cool the NVP crude product generated by the reaction to 20-50° C., and is connected to the 1# pressure control tank 18.

[0113] The 1# pressure control tank 18 is used to control the pressure of the NVP crude product generated by the reaction to 3.5~4.5Mpa, and is connected to the Venturi ejector of the next stage series structure (i.e., the 2# Venturi ejector 21). This is different from the pressure control tank of the last three stages series structure (i.e., the 3# pressure control tank 38) which is connected to the crude product tank 39.

[0114] Second, as Figure 6 As shown, an embodiment of the present invention provides a production process for producing a tubular reactor based on the above-mentioned NVP, comprising:

[0115] S1, the raw material acetylene gas and nitrogen mixed gas is compressed to a pressure of 1.3-1.8Mpa through compressor 01, and then decompressed and circulated to a flow rate of 20-60m through inlet cooler 02. 3 / h; the volume proportion of acetylene in the mixed gas is 45% to 55%.

[0116] S2, adding raw material 2-P into a preparation kettle, then adding solid potassium hydroxide for dissolution reaction and removing water in vacuo, preparing qualified potassium pyrrolidone liquid and putting it into 2-P stirring kettle 20, pumping it into 2-P pressure control tank through 2-P metering pump, and controlling the pressure at 3.5-4.5Mpa; wherein the potassium pyrrolidone liquid material contains 2-pyrrolidone with a mass fraction of 98%-99.5% and potassium pyrrolidone with a mass fraction of 0.5%-2%.

[0117] S3, at the first stage of the series structure:

[0118] The 2-P flow rate delivered from the bottom of the 2-P pressure control tank 04 is controlled to be 280-320L / h, and the mixed gas with the acetylene gas and nitrogen delivered from the high-pressure acetylene circulating gas pipe 08 is mixed with gas and liquid in the 1# Venturi injector 11 and the 1# static mixer 12, and cooled in the 1# cooler 19 before entering the 1# inlet buffer tank 13, with the pressure maintained at 1.5-2.5Mpa. The top of the 1# inlet buffer tank 13 is decomposed and returned to the high-pressure acetylene circulating gas pipe 08, and is regularly replaced and emptied to the flare;

[0119] The steam is pressurized to 3.5-4.5 MPa by the 1# metering pump 14 and pumped into the 1# preheater 15. The steam is preheated to 100-130°C and enters the 1# tubular reactor 16. The reaction temperature is 160-180°C and the reaction pressure is 3.5-4.5 MPa.

[0120] After the reaction, it enters the 1# product cooler 17, and after being cooled to 30-45°C, it enters the 1# pressure control tank 18, where the pressure is stabilized at 3.5-4.5 MPa, and enters the secondary series structure.

[0121] S4, at the second-stage series structure:

[0122] The crude NVP product flow rate from the bottom of the 1# pressure control tank 18 is controlled to be 280-320L / h, and the mixed gas with the acetylene gas and nitrogen sent from the high-pressure acetylene circulating gas pipe 08 enters the 2# inlet buffer tank 23 after gas-liquid mixing through the 2# venturi injector 21 and the 2# static mixer 22 and cooling by the 2# cooler, with the pressure maintained at 1.5-2.5Mpa. The top decomposed gas of the 2# inlet buffer tank 23 returns to the high-pressure acetylene circulating gas pipe 08, and is regularly replaced and emptied to the torch; wherein the crude NVP product contains 10%-40% NVP by mass and 0.5%-2% of the catalyst potassium pyrrolidone;

[0123] The steam is pressurized to 3.5-4.5 MPa by the 2# metering pump 24 and pumped into the 2# preheater 25. The steam is preheated to 100-130°C and enters the 2# tubular reactor 26. The reaction temperature is 160-180°C and the reaction pressure is 3.5-4.5 MPa.

[0124] After the reaction, it enters the 2# product cooler 27, and after being cooled to 30-45°C, it enters the 2# pressure control tank 28, where the pressure is stabilized at 3.5-4.5 MPa, entering a three-stage series structure.

[0125] S5. At the third-level series structure:

[0126] The crude NVP product flow rate from the bottom of the 2# pressure control tank 28 is controlled to be 280-320L / h, and the mixed gas with the acetylene gas and nitrogen sent from the high-pressure acetylene circulating gas pipe 08 is mixed with gas and liquid in the 3# Venturi injector 31 and the 3# static mixer 32, and cooled in the 3# cooler 40 before entering the 3# inlet buffer tank 33, with the pressure maintained at 1.5-2.5Mpa. The top of the 3# inlet buffer tank 33 is decomposed and returned to the high-pressure acetylene circulating gas pipe 08, and is regularly replaced and emptied to the flare;

[0127] The steam is pressurized to 3.5-4.5 MPa by the 3# metering pump 34 and pumped into the 3# preheater 35. The steam is preheated to 100-130°C and enters the 3# tubular reactor 36. The reaction temperature is 160-180°C and the reaction pressure is 3.5-4.5 MPa.

[0128] After the reaction, it enters the 3# product cooler 37, and after being cooled to 30-45°C, it enters the 3# pressure control tank 38, where the pressure is stabilized at 3.5-4.5Mpa. The bottom material of the 3# pressure control tank 38 is decompressed to normal pressure and enters the crude product tank 39, and finally enters the distillation device 41 to be purified into fine products.

[0129] In an optional embodiment, the S1 is compressed to a pressure of 1.4-1.6 MPa by a compressor 01.

[0130] In an optional embodiment, the 1# cooler 19 in S3 is cooled to less than 40°C and then enters the 1# inlet buffer tank 13, and 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°C and then enters the 2# inlet buffer tank 23, and 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°C and then enters the 3# inlet buffer tank 33, and the pressure at the 3# pressure control tank 38 is 3.8-4.3 MPa.

[0131] In an optional embodiment, in order to generate sufficient negative pressure to absorb the gas to participate in the reaction due to the Venturi effect, the 2-P pressure at the inlet of the 1# Venturi injector 11 in S3 is 0.5 to 2.5 MPa higher than the pressure of the acetylene gas and nitrogen mixed gas, preferably 1.0 to 1.5 MPa.

[0132] Similarly, the pressure of the NVP crude product at the inlet of the 2# Venturi ejector 21 in S4 is 0.5-2.5 MPa higher than the pressure of the acetylene gas and nitrogen mixed gas, and preferably 1.0-1.5 MPa.

[0133] In order to better understand the NVP production tubular reactor and production process provided by the embodiment of the present invention, the following specific comparative experiments are provided:

[0134] Comparative Example:

[0135] A traditional bubbling reactor was used, and the experimental parameters were: the α~P flow rate was set to 300L / h; the acetylene flow rate was 30m 3 / h; the reaction pressure is maintained in the range of 1.4-1.5Mpa; the reaction temperature is controlled in the range of 140-160℃.

[0136] Embodiment 1:

[0137] The novel reactor provided in the embodiment of the present invention is used, and the experimental parameters are: 2~P flow / NVP crude product flow is 300L / h, acetylene flow is 30m 3 / h, the reaction pressure is between 3.5 and 4.5 MPa, and the reaction temperature is between 160 and 180°C.

[0138] Embodiment 2:

[0139] Using the novel reactor provided in the embodiment of the present invention, the experimental parameters are as follows: 2~P flow / NVP crude product flow is increased to 310L / h, acetylene flow is increased to 32m 3 / h, the reaction pressure is also 3.5-4.5Mpa, and the reaction temperature is 160-180°C.

[0140] Embodiment 3:

[0141] Using the novel reactor provided in the embodiment of the present invention, the experimental parameters are as follows: 2~P flow / NVP crude product flow is reduced to 290L / h, acetylene flow is reduced to 28m 3 / h, the reaction pressure is maintained at 3.5-4.5Mpa, and the reaction temperature is 160-180°C.

[0142] Comparison of experimental results

[0143] 1. NVP content in crude product

[0144] The NVP content in the crude product obtained from the traditional bubbling reactor is only 42%.

[0145] The new reactor showed higher NVP content in different embodiments, reaching 65% in Example 1, 68% in Example 2, and 66% in Example 3. The average content was about 66.2%, which was about 57.6% higher than that of the traditional bubbling reactor.

[0146] That is, by improving the optimal combination of reaction pressure and temperature, the new reactor significantly increases the NVP content in the crude product. Compared with the traditional bubbling reactor, the average content increase is 57.6%, which means that with the same raw material input, the new reactor can produce more NVP products, significantly improving production efficiency and product yield.

[0147] 2. NVP synthesis reaction selectivity

[0148] The selectivity of NVP synthesis reaction in traditional bubble reactor is 90%.

[0149] The selectivity of the NVP synthesis reaction of the new reactor in Example 1 is 94.1%, in Example 2 is 95.2%, and in Example 3 is 95.8%. The average selectivity is about 95.03%, which is about 5.03% higher than that of the traditional bubbling reactor.

[0150] That is, the new reactor also has significant improvements in the selectivity of NVP synthesis reaction, with an average selectivity increase of about 5.58%. This shows that during the reaction process, the new reactor can more accurately promote the reaction of 2-P and acetylene to generate NVP, reduce the occurrence of side reactions, and help improve product purity and reduce subsequent separation and purification costs.

[0151] In addition, it can be seen from the experimental data that the new reactor has smaller fluctuations in NVP content and NVP selectivity in the crude product under different embodiments. For example, the NVP content fluctuates between 65% and 68%, and the NVP selectivity fluctuates between 94.1% and 95.8%. However, due to the limitations of its own structure and reaction conditions, the traditional bubbling reactor may cause large fluctuations in product quality due to slight changes in factors such as temperature and pressure during the reaction process. The stability advantage of the new reactor makes it more suitable for long-term, large-scale industrial production applications, and can ensure the consistency and stability of product quality.

[0152] In summary, the experimental results show that the reactor provided by the embodiment of the present invention improves the synthesis efficiency of NVP, and the crude product content is increased from 40% to 45% in the bubbling reactor to 55% to 75%, which is more than 10% to 30% higher than the prior art. At the same time, the selectivity reaches more than 94%, which is significantly better than the prior art.

[0153] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the statement "comprise one..." do not exclude the presence of other identical elements in the process, method, article or device including the elements.

[0154] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A NVP production tubular reactor, characterized in that: It includes a raw material acetylene gas conveying device and at least one stage of series structure, wherein the series structure includes a venturi ejector, a static mixer, a cooler, a tubular reactor and a pressure control tank; The inlet of the venturi ejector 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 is composed of a plurality of tubular reaction units connected in series and is used for carrying out the NVP synthesis reaction of the gas-liquid mixture transported by the 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 ejector of the next stage series structure.

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

3. The NVP production tubular reactor according to 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 the 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 the 2-pyrrolidone liquid material and is connected to the inlet of the venturi injector through a pipeline.

4. The NVP production tubular reactor according to claim 1, characterized in that: The series structure also includes an inlet buffer tank, a metering pump and a preheater; The inlet of the inlet 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 and is used for secondary pressurizing the 2-pyrrolidone liquid material or the NVP crude product and pumping it to the preheater; The preheater is used to steam preheat the secondary pressurized 2-pyrrolidone liquid material or NVP crude product, and is connected to the inlet of the tubular reactor.

5. The NVP production tubular reactor according to 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, is used to cool the NVP crude product generated by the reaction, and is connected to the pressure control tank.

6. The NVP production tubular reactor according to claim 1, characterized in that: 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; Part of the acetylene gas from the raw acetylene gas main is pressurized by the compressor to the high-pressure acetylene circulation gas pipe and connected to the inlet of the Venturi injector; the other part is cooled by the inlet cooler, decompressed to the low-pressure acetylene circulation gas pipe, and circulated with the compressor.

7. The NVP production tubular reactor according to claim 1, characterized in that: The NVP production tubular reactor also includes a crude product tank, and the pressure control tank of the last stage of the series structure is connected to the crude product tank.

8. A production process for producing a tubular reactor of NVP based on any one of claims 1 to 7, characterized in that: include: S1. The raw material acetylene gas and nitrogen mixed gas is compressed to a pressure of 1.3-1.8Mpa by a compressor, and then decompressed and circulated to a flow rate of 20-60m3 by an imported cooler. 3 / h; the volume proportion of acetylene in the mixed gas is 45% to 55%; S2, adding raw material 2-P to a preparation kettle, adding solid potassium hydroxide to dissolve and remove water in vacuo, preparing a qualified potassium pyrrolidone liquid and putting it into a 2-P stirring kettle, and pumping it into a 2-P pressure control tank through a 2-P metering pump, and the pressure is controlled at 3.5-4.5Mpa; wherein the potassium pyrrolidone liquid material contains 2-pyrrolidone with a mass fraction of 98%-99.5% and potassium pyrrolidone with a mass fraction of 0.5%-2%; S3, at the first stage of the series structure: The 2-P flow rate delivered from the bottom of the 2-P pressure control tank is controlled to be 280-320L / h. The mixed gas with acetylene gas and nitrogen delivered from the high-pressure acetylene circulating gas pipe is mixed with gas and liquid in the 1# Venturi ejector and the 1# static mixer and cooled in the 1# cooler before entering the 1# inlet buffer tank. The pressure is maintained at 1.5-2.5Mpa. The decomposed gas at the top of the 1# inlet buffer tank returns to the high-pressure acetylene circulating gas pipe and is regularly replaced and vented to the flare. The 1# metering pump pressurizes the steam to 3.5-4.5Mpa and pumps it into the 1# preheater. The steam is preheated to 100-130°C and enters the 1# tubular reactor. The reaction temperature is 160-180°C and the reaction pressure is 3.5-4.5Mpa. After the reaction, it enters the 1# product cooler, cools to 30-45°C, and then enters the 1# pressure control tank, where the pressure is stabilized at 3.5-4.5Mpa, and enters the secondary series structure; S4, at the second-stage series structure: The crude NVP product flow rate from the bottom of the 1# pressure control tank is controlled to be 280-320L / h, and the mixture gas with acetylene gas and nitrogen sent from the high-pressure acetylene circulating gas pipe is mixed with gas and liquid in the 2# Venturi ejector and the 2# static mixer, and then cooled in the 2# cooler before entering the 2# inlet buffer tank. The pressure is maintained at 1.5-2.5Mpa, and the top of the 2# inlet buffer tank is returned to the high-pressure acetylene circulating gas pipe, and is regularly replaced and vented to the torch; the crude NVP product contains 10%-40% NVP by mass and 0.5%-2% of the catalyst potassium pyrrolidone; The 2# metering pump pressurizes the steam to 3.5-4.5Mpa and pumps it into the 2# preheater. The steam is preheated to 100-130°C and enters the 2# tubular reactor. The reaction temperature is 160-180°C and the reaction pressure is 3.5-4.5Mpa. After the reaction, it enters the 2# product cooler, cools to 30-45°C, and then enters the 2# pressure control tank, where the pressure is stabilized at 3.5-4.5Mpa, and enters the three-stage series structure; S5. At the third-level series structure: The crude NVP product flow rate from the bottom of the 2# pressure control tank is controlled to be 280-320L / h. The crude NVP product is mixed with the acetylene gas and nitrogen from the high-pressure acetylene circulating gas pipe. After being mixed with gas and liquid by the 3# Venturi ejector and the 3# static mixer and cooled by the 3# cooler, it enters the 3# inlet buffer tank. The pressure is maintained at 1.5-2.5Mpa. The decomposed gas at the top of the 3# inlet buffer tank returns to the high-pressure acetylene circulating gas pipe and is regularly replaced and vented to the flare. The 3# metering pump pressurizes the steam to 3.5-4.5Mpa and pumps it into the 3# preheater. The steam is preheated to 100-130℃ and enters the 3# tubular reactor. The reaction temperature is 160-180℃ and the reaction pressure is 3.5-4.5Mpa. After the reaction, it enters the 3# product cooler, and after being cooled to 30-45°C, it enters the 3# pressure control tank, where the pressure is stabilized at 3.5-4.5Mpa. It then enters the distillation device through the crude product tank to be purified into fine products.

9. The production process according to claim 8, characterized in that: include: The S1 is compressed to a pressure of 1.4-1.6 MPa by a compressor; and / or After the 1# cooler in S3 cools to less than 40°C, it enters the 1# inlet buffer tank, and the pressure at the 1# pressure control tank is 3.8-4.3Mpa; After the 2# cooler in S4 cools to less than 40°C, it enters the 2# inlet buffer tank, and the pressure at the 2# pressure control tank is 3.8-4.3Mpa; After the 3# cooler in S5 cools to less than 40°C, it enters the 3# inlet buffer tank, and the pressure at the 3# pressure control tank is 3.8-4.3Mpa.

10. The production process according to claim 8, characterized in that: The 2-P pressure at the inlet of the 1# Venturi injector in S3 is 0.5 to 2.5 MPa higher than the pressure of the acetylene gas and nitrogen mixed gas; The NVP crude product pressure at the inlet of the 2# Venturi injector in S4 is 0.5-2.5 MPa higher than the pressure of the acetylene gas and nitrogen mixed gas; The NVP crude product pressure at the inlet of the 3# Venturi injector in S5 is 0.5 to 2.5 MPa higher than the pressure of the acetylene gas and nitrogen mixed gas.

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