WO2021208201A1

WO2021208201A1 - External micro-interface ammoximation reaction system and method

Info

Publication number: WO2021208201A1
Application number: PCT/CN2020/092779
Authority: WO
Inventors: 张志炳; 周政; 张锋; 李磊; 孟为民; 王宝荣; 杨高东; 罗华勋; 杨国强; 田洪舟; 曹宇
Original assignee: 南京延长反应技术研究院有限公司
Priority date: 2020-04-13
Filing date: 2020-05-28
Publication date: 2021-10-21
Also published as: CN111574398A

Abstract

The present invention provides an external micro-interface ammoximation reaction system and method. The external micro-interface ammoximation reaction system comprises an oximation reactor, a reaction clear liquid buffer tank, a tert-butanol recovery tower, an extraction tank, a water washing separator, a toluene oxime storage tank, a first rectifying tower, a second rectifying tower and a rearrangement reaction device, wherein a feeding hole is provided in a side wall of the oximation reactor and is connected to a micro-interface generator for dispersing and breaking gas into bubbles; a first inlet is provided in the middle of a side wall of the first rectifying tower, a first outlet is provided in the bottom of the first rectifying tower, a second inlet is provided in the upper portion of a side wall of the second rectifying tower, and a second outlet is provided in the bottom of the second rectifying tower; and the first inlet is connected to the top of the toluene oxime storage tank for leaving toluene oxime to stand and cool first before rectifying same, and the second outlet is connected to the rearrangement reaction device for carrying out a rearrangement reaction. According to the present invention, the micro-interface generator is arranged before the oximation reactor, such that the mass transfer area between ammonia gas and a liquid phase is increased, and the temperature and the pressure of an oximation reaction are reduced, thereby effectively reducing the energy consumption and improving the reaction efficiency.

Description

An external micro-interface ammoximation reaction system and method

Technical field

The invention belongs to the technical field of micro-interface strengthening reactions, and specifically relates to an external micro-interface ammoximation reaction system and method.

Background technique

At present, caprolactam is mainly prepared by Beckman rearrangement and translocation of cyclohexanone oxime. The main processes for preparing cyclohexanone oxime include the hydroxylamine phosphate method (HPO) represented by DSM technology and the domestically developed Cyclohexanone ammoximation method (HAO). The latter uses silicon-titanium molecular sieve TS-1 as a catalyst. The raw materials cyclohexanone, dilute hydrogen peroxide, and ammonia are synthesized in one step to obtain cyclohexanone oxime under certain operating conditions. The process has mild reaction conditions, simple operation and high atom utilization. It is environmentally friendly, so it has been favored by the caprolactam industry in recent years. Although the cyclohexanone ammoximation process has obvious advantages, it also has some shortcomings. On the one hand, the gas-liquid mass transfer area of the existing oximation reactor is limited. It is fully mixed, resulting in incomplete conversion of cyclohexanone, low oximation conversion rate, and increasing the occurrence of side reactions; on the other hand, the ammoximation reaction is a strong exothermic reaction (301KJ/mol), and the temperature is too high, increasing The decomposition products of cyclohexanone and cyclohexanone oxime are not easily removed in the subsequent process, which affects the yield and quality of the final product caprolactam. In order to improve the reaction efficiency of cyclohexanone oximation, reduce the reaction temperature and pressure, and reduce the occurrence of side reactions, it is necessary to improve the current process.

In view of this, the present invention is proposed.

Summary of the invention

The first object of the present invention is to provide an external micro-interface ammoximation reaction system. After the micro-interface generator is installed before the oximation reactor, the reaction system can disperse and break the ammonia gas into micron diameter. The micro-bubbles increase the phase boundary area between the ammonia gas and the liquid phase material, so that the mass transfer space is fully satisfied, and the residence time of the ammonia gas in the liquid phase is increased, and the ammonia consumption is reduced, thereby greatly increasing the oxime Chemical reaction efficiency, effectively inhibit side reactions, and significantly reduce the energy consumption of the reaction process; on the other hand, the reaction temperature and pressure are reduced, the decomposition products of cyclohexanone and cyclohexanone oxime are reduced, and the yield and quality of the final product caprolactam are improved. , And it reduces energy consumption and improves system security.

The second object of the present invention is to provide a method for reaction using the above reaction system, which has milder operating conditions, reduces the temperature and pressure of the oximation reaction while ensuring the reaction efficiency, and has high safety performance and energy consumption. Low, achieving a better reaction effect than the existing process.

In order to achieve the above objectives of the present invention, the following technical solutions are specially adopted:

The invention provides an external micro-interface ammoximation reaction system, which includes an oximation reactor, a reaction clear liquid buffer tank, a tert-butanol recovery tower, an extraction tank, a water washing separator, a toluoxime storage tank, and a first distillation Tower, second rectification tower and rearrangement reaction device, of which,

The side wall of the oximation reactor is provided with a feed port, and the feed port is connected with a micro-interface generator for dispersing the crushed gas into bubbles; an external circulation device is provided outside the oximation reactor for controlling For the temperature inside the oximation reactor, one end of the external circulation device is connected to the side wall of the oximation reactor, and the other end is connected to the micro-interface generator;

The bottom of the oximation reactor is connected to the reaction clear liquid buffer tank, and the material from the reaction clear liquid buffer tank is passed through the middle section of the tert-butanol recovery tower for the recovery of tert-butanol; The extraction tank is provided with a liquid inlet and a light phase discharge port, the liquid inlet is connected to the bottom of the tert-butanol recovery tower, and the light phase discharge port is connected to the water washing separator for comparison. The toluoxime solution is washed with water; the toluoxime that has passed the water washing of the water-washing separator passes into the toluoxime storage tank, and the middle of the side wall of the first distillation tower is provided with a first inlet, and the bottom is provided with a first outlet A second inlet is arranged on the side wall of the second rectification tower, and a second outlet is arranged at the bottom. The first inlet is connected with the top of the toluoxime storage tank to be used before the Let it stand for cooling first, the first outlet is connected with the second inlet, and the second outlet is connected with the rearrangement reaction device to perform a rearrangement reaction.

In the prior art, the cyclohexanone ammoximation reaction has the following problems: On the one hand, the gas-liquid mass transfer area of the existing oximation reaction is limited. The conversion of hexanone is not complete, and the conversion rate of oximation is low, which increases the occurrence of side reactions; on the other hand, the ammoximation reaction is a strong exothermic reaction, and the temperature is too high, which increases the decomposition of cyclohexanone and cyclohexanone oxime. Products, these products are not easily removed in the subsequent process, which affects the yield and quality of the final product caprolactam. The external micro-interface ammoximation reaction system of the present invention is equipped with a micro-interface generator before the oximation reactor. On the one hand, the ammonia gas can be dispersed and broken into micro-sized bubbles with a diameter of micrometers, and ammonia gas and liquid phase materials can be added. The area between the phase boundaries makes the mass transfer space fully satisfied, and increases the residence time of ammonia in the liquid phase, reduces the consumption of ammonia, thereby greatly improving the efficiency of the oximation reaction, effectively inhibiting side reactions, and significantly reducing The energy consumption of the reaction process; on the other hand, the reaction temperature and pressure are reduced, the decomposition products of cyclohexanone and cyclohexanone oxime are reduced, the yield and quality of the final product caprolactam are improved, and energy consumption is reduced, and system safety is improved. sex.

Further, the micro-interface generator is not limited in the manner of setting, the set position is not limited, and the number is not limited; the micro-interface generator can be connected to the feed port of the oximation reactor by welding or flange; in addition; More preferably, the oximation reactor can be equipped with multiple micro-interface generators in series or in parallel, and the multiple micro-interface generators can all be connected to the feed port of the reactor.

Further, the micro-interface generator is a pneumatic micro-interface generator, and the number of micro-interface generators is at least one. Ammonia gas enters into the pneumatic micro-interface generator, and through the crushing and dispersing action of the pneumatic micro-interface generator, the ammonia gas is dispersed and broken into micro-bubbles, thereby reducing the thickness of the liquid film and effectively increasing the ammonia and liquid materials The mass transfer area between them reduces the mass transfer resistance and improves the reaction efficiency.

Further, the rearrangement reaction device includes a first-stage rearrangement tank, a second-stage rearrangement tank, and a third-stage rearrangement tank connected in series; the first-stage rearrangement tank, the second-stage rearrangement tank, and the third-stage rearrangement tank The tops of the two are connected with the second outlet through a pipe. Cyclohexanone oxime enters the first-stage rearrangement tank, the second-stage rearrangement tank and the third-stage rearrangement tank respectively according to a certain proportion. In the presence of fuming sulfuric acid, cyclohexanone oxime is converted into caprolactam through Beckmann molecular rearrangement. The primary rearrangement liquid in the secondary rearrangement tank overflows from the upper part of the tank and mixes with the bottom material of the secondary rearrangement tank, then enters the secondary rearrangement tank and reacts with the newly added cyclohexanone oxime; the secondary rearrangement tank After the secondary rearrangement liquid overflows from the upper part of the tank and mixes with the bottom material of the tertiary rearrangement tank, it enters the tertiary rearrangement tank and reacts with the newly added cyclohexanone oxime. The final product is removed from the tertiary rearrangement tank. The upper part of the tank overflows for collection.

More preferably, the rearrangement reaction device may further be provided with a plurality of rearrangement tanks connected in series to form a multi-stage continuous rearrangement reaction, and the tops of the plurality of rearrangement tanks connected in series are all connected to the second outlet. The multi-stage continuous rearrangement reaction can shorten the reaction time of each stage rearrangement reaction, reduce the occurrence of side reactions in the rearrangement process, and increase the yield of the product.

Further, the first-stage rearrangement tank, the second-stage rearrangement tank, and the third-stage rearrangement tank are all provided with a rearrangement liquid circulation pipeline for controlling the temperature in the tank, and the material from the previous-stage rearrangement tank is connected Into the rearrangement liquid circulation pipeline of the rearrangement tank of the next stage. Because the Beckman rearrangement reaction is an exothermic reaction, the higher the temperature during the reaction, a series of side reactions will occur under acidic conditions, and the by-product ammonium sulfate will increase greatly, which affects the purity of caprolactam, so it is necessary to set the rearrangement The liquid circulation pipeline uses the circulation heat of the circulation pipeline to derive the reaction heat, thereby effectively smoothing the reaction and reducing the temperature of the reaction in the tank.

Further, a rearrangement circulation pump, a rearrangement heat exchanger and a three-way valve are provided on the rearrangement liquid circulation pipeline, and the three-way valve is located between the rearrangement circulation pump and the rearrangement heat exchanger; A bypass channel is provided in communication with the three-way valve, and the bypass channel is used for working conditions without heat exchange. In the initial stage of the rearrangement reaction, the temperature is relatively low. The reaction liquid enters the rearrangement tank from the bypass channel to carry out the rearrangement reaction. As the reaction progresses, a large amount of heat is released. The generated heat is removed, and then circulated into the rearrangement reaction tank for the rearrangement reaction to form a rearrangement liquid circulation pipeline, so as to maintain the reaction temperature in the rearrangement tank within a certain range. Preferably, the rearrangement heat exchanger is preferably a plate heat exchanger. Compared with other heat exchangers, the plate heat exchanger has the characteristics of high heat exchange efficiency, low heat loss, high efficiency and energy saving, and easy cleaning and disassembly.

Further, the pipeline between the second outlet and the rearrangement reaction device is provided with an oxime cooler and an oxime buffer tank connected in sequence for cooling before the cyclohexanone oxime undergoes the rearrangement reaction, so The oxime cooler is connected to the second outlet, and the oxime buffer tank is connected to the rearrangement reaction device. Since the rearrangement reaction is a strong exothermic reaction, the cyclohexanone oxime is cooled to a certain temperature before the rearrangement reaction is carried out and then enters the rearrangement reaction device. The oxime cooler is a shell-and-tube cooler. The type of cooler is simple in structure, low in cost, wide in circulation cross-section, and easy to clean scale. The shell and tube cooler is made of Hastelloy. Compared with other materials, Hastelloy has better corrosion resistance and thermal stability. Therefore, the use of Hastelloy can increase the life of the cooler.

Further, the first rectification tower is composed of a rectification section and a stripping section, and the second rectification tower is composed of a stripping section. After heating by the heater, toluene oxime enters the first rectification tower from the first inlet. The top of the first rectification tower recovers toluene that does not contain oxime. The oxime solution containing a small amount of toluene in the tower still passes through the first outlet The second inlet enters the second rectification tower, the toluene containing a small amount of oxime is vaporized from the top of the second rectification tower, and the cyclohexanone oxime in the tower still enters the oxime buffer tank after being cooled through the second outlet.

Further, the rectification section and the stripping section in the first rectification tower can be composed of a number of trays and packings. Preferably, the stripping section adopts the structure of trays, and the rectification section adopts the structure of packing, because the tower The pressure drop of the plate itself is relatively large, and the pressure drop of the packing is relatively small; the stripping section of the second rectification tower adopts a packing structure, and the type of packing is Pall ring packing. This packing has large production capacity, strong resistance, and large operating flexibility. Features.

Further, the top of the first rectification column is provided with a first top condenser, the first top condenser is connected to a first receiving tank, and the first receiving tank is connected to the first receiving tank through a transfer pump. The side wall of a rectification column is connected for reflux at the top of the column; the top of the second rectification column is provided with a second top condenser, and the second top condenser is connected with the second receiving tank, so The second receiving tank is connected to a toluene deoxime tower for separating toluene and oxime.

Further, both the first rectification tower and the second rectification tower are provided with a vacuum device to ensure that the rectification tower is operated under vacuum conditions. Under vacuum conditions, the stability and continuity of feeding and discharging can be guaranteed, so as to achieve the purpose of improving the distillation rate. The evacuation device is a jet pump, which continuously evacuates the vacuum through the jet pump, so as to maintain the vacuum degree in the tower.

Further, the bottom of the water washing separator is provided with a washing water circulation pipeline for returning the washing water to the water washing separator for washing and purification again; the washing water circulation pipeline is provided with a washing circulation pump. By setting the washing water circulation pipeline, the washing water can be returned to the washing separator through the washing water circulation pipeline for multiple washing and purification, thereby avoiding the waste of toluoxime. More advantageously, the washing water volume can be adjusted by setting the washing circulating pump, the load of washing water can be reduced, and the washing effect can be improved.

Further, the reaction system includes a pre-filter and a coalescer connected in sequence, and the pre-filter is connected to the top of the water-washing separator for toluene oxime pre-filtering and entering the coalescer to separate impurities Finish washing. After washing with water, the toluene oxime first enters the pre-filter for filtration, and then enters the coalescer for further separation and purification of impurities, and finally the qualified concentration of toluene oxime is sent to the toluoxime tank; the pre-filter can filter out larger ones in the medium The solid particle impurities can prevent the filter element of the coalescer from clogging, and the filtering precision of the pre-filter is less than or equal to 15 μm.

Further, the reaction system includes a water extraction tower and an extraction liquid receiving tank connected in sequence to receive the organic phase extracted from the top of the water extraction tower. The organic phase extracted from the top of the water extraction tower overflows into the extraction liquid receiving tank, and then returns to the toluoxime cooler by a transfer pump for cooling, and then enters the toluoxime extraction system again for extraction and water washing, thereby avoiding Waste of cyclohexanone oxime.

Further, the reaction system includes a tail gas absorption tower, the tail gas absorption tower is connected to the top of the oximation reactor, the bottom of the tail gas absorption tower is also provided with an absorption liquid outlet, and the absorption liquid outlet is connected to the The oximation reactor is used for the absorption liquid to return to the oximation reactor for utilization.

Further, the middle section of the tert-butanol recovery tower is respectively provided with a liquid inlet and a gas inlet, the liquid inlet is connected to the bottom of the reaction clear liquid buffer tank; the gas inlet is connected to the top of the reaction clear liquid buffer tank connect. The liquid in the reaction clear liquid buffer tank enters the tert-butanol recovery tower from the liquid inlet, and the gas in the reaction clear liquid buffer tank enters the tert-butanol recovery tower from the gas inlet. The gas inlet and the liquid inlet are changed because the material composition in the reaction clear liquid buffer tank is more complicated. Most of the tert-butanol exists in liquid form, and a small amount of it exists in the reaction product in gaseous form. This way, the gas inlet and liquid inlet are set up. The dual-material imports can ensure the full recycling of tert-butanol.

Further, the reaction system includes a tert-butanol reflux tank, the tert-butanol reflux tank is provided with a non-condensable gas outlet, and the non-condensable gas in the tert-butanol reflux tank is mixed with the tail gas through the non-condensable gas outlet Enter the tail gas absorption tower for recycling.

Further, the reaction system further includes a circulating tert-butanol tank, the top of the circulating tert-butanol tank is connected to the bottom of the tert-butanol reflux tank, and the bottom of the circulating tert-butanol tank is connected to the oximation tank. The bottom of the reactor is connected so that tert-butanol can be reused as a reaction solvent. A small part of the condensate in the tert-butanol reflux tank is used for reflux at the top of the tower, and most of the remaining part is fed into the oximation reactor through the circulating tert-butanol tank to be reused as a reaction solvent, which reduces the use cost of tert-butanol.

In addition, the present invention also provides a method of oximation reaction, which includes the following steps:

After the ammonia gas is dispersed and broken into microbubbles, it undergoes a catalytic oximation reaction with the liquid phase materials; the reaction product is collected as a clear liquid and then recovered for tert-butanol; the oxime aqueous solution after the tertiary butanol is recovered is then extracted and washed with toluene; After washing with water, toluoxime enters the rearrangement reaction after rectification.

Further, the ammonia gas is introduced into the micro-interface generator set before the oximation reactor to break it into micro-bubbles with a diameter of micrometers. After the ammonia gas is dispersed and broken into micro-bubbles, it is catalyzed with the liquid phase material. Oximation reaction.

In the process of the catalytic oximation reaction, the unreacted gas is recovered and used as tail gas, and the reaction product is collected in a clear liquid manner and then enters the reaction clear liquid buffer tank, and then enters the tert-butanol recovery tower for the reaction product The tert-butanol in the oximation reactor is recovered, and the recovered tert-butanol enters the oximation reactor again to be used as the reaction solvent; the oxime aqueous solution after the recovery of the tert-butanol is cooled by the toluoxime cooler and then enters the extraction tank for use The solubility of toluene to oxime extracts the oxime from the aqueous oxime solution into the toluene phase. The toluene oxime solution is separated from the light phase discharge port of the extraction tank and enters the water washing separator, which is completed in the water washing separator and coalescer using desalinated water. After washing with water, the qualified toluoxime enters the toluoxime tank from the coalescer; then it is heated by a heater and then enters the first distillation tower. The top of the first distillation tower recovers toluene containing almost no oxime. The tower still contains A small amount of toluene oxime solution exits from the first outlet and enters the second rectification tower through the second inlet. The cyclohexanone oxime in the second rectification tower is cooled down and enters the rearrangement reaction device for rearrangement through the second outlet. reaction.

Further, the temperature of the oximation reaction is 80-84°C, and the pressure is 0.19-0.22 MPa.

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

The present invention can disperse and break the ammonia gas into micro-sized micro-bubbles with a diameter of micrometers by installing a micro-interface generator before the oximation reactor, increase the phase boundary area between the ammonia gas and the liquid phase material, and make the mass transfer space Fully satisfy, and increase the residence time of ammonia in the liquid phase, reduce the consumption of ammonia, thereby greatly improving the efficiency of the oximation reaction, effectively inhibiting side reactions, and significantly reducing the energy consumption of the reaction process; on the other hand, it reduces The reaction temperature and pressure reduce the decomposition products of cyclohexanone and cyclohexanone oxime, increase the yield and quality of the final product caprolactam, reduce energy consumption, and improve system safety.

Description of the drawings

By reading the detailed description of the preferred embodiments below, various other advantages and benefits will become clear to those of ordinary skill in the art. The drawings are only used for the purpose of illustrating the preferred embodiments, and are not considered as a limitation to the present invention. Also, throughout the drawings, the same reference symbols are used to denote the same components. In the attached picture:

Fig. 1 is a schematic structural diagram of an external micro-interface ammoximation reaction system provided by an embodiment of the present invention.

Description of the drawings:

10-oximation reactor; 11-feeding port-;

12-Exhaust gas outlet; 20-Reaction clear liquid buffer tank;

30-tert-butyl alcohol recovery tower; 31-liquid import;

32-Gas import; 33-Export of oxime aqueous solution;

40-extraction tank; 41-liquid inlet;

42-Light phase outlet; 43-Water phase outlet;

50-water washing separator; 60-toluene oxime storage tank;

70-First distillation tower; 71-First import;

72-First exit; 710-First tower top condenser;

720-first receiving tank; 80-second distillation tower;

81-Second Import; 82-Second Export;

810-Second tower top condenser; 820-Second receiving tank;

90-rearrangement reaction device; 91-first-level rearrangement tank;

92-Second-level rearrangement tank; 93-Three-level rearrangement tank;

910-rearrangement circulating pump; 920-rearrangement heat exchanger;

930-three-way valve; 100-micro interface generator;

110-External filtration device; 120-tert-butanol return tank;

121-Non-condensable gas export; 130-Circulating tert-butanol tank;

140-water extraction tower; 150-pre-filter;

160- coalescer; 170- extraction liquid receiving tank;

180-toluene deoxime tower; 190-heater;

200-oxime cooler; 210-oxime buffer tank;

220-Exhaust gas absorption tower; 221-Absorption fluid outlet.

Detailed ways

The technical solutions of the present invention will be clearly and completely described below in conjunction with the accompanying drawings and specific implementations. However, those skilled in the art will understand that the embodiments described below are part of the embodiments of the present invention, rather than all of them. It is only used to illustrate the present invention and should not be regarded as limiting the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work shall fall within the protection scope of the present invention. If no specific conditions are indicated in the examples, it shall be carried out in accordance with the conventional conditions or the conditions recommended by the manufacturer. The reagents or instruments used without the manufacturer's indication are all conventional products that can be purchased on the market.

In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. The indicated orientation or positional relationship is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the pointed device or element must have a specific orientation or a specific orientation. The structure and operation cannot therefore be understood as a limitation of the present invention. In addition, the terms "first", "second", and "third" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance.

In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installation", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection or a detachable connection. Connected or integrally connected; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the internal communication between two components. For those of ordinary skill in the art, the specific meanings of the above-mentioned terms in the present invention can be understood in specific situations.

In order to explain the technical solutions of the present invention more clearly, the following description will be given in the form of specific embodiments.

Example

Referring to Figure 1, it is an external micro-interface ammoximation reaction system of an embodiment of the present invention, including an oximation reactor 10, a reaction clear liquid buffer tank 20, a tert-butanol recovery tower 30, an extraction tank 40, and a water washing separator 50. The toluoxime storage tank 60, the first rectification tower 70, the second rectification tower 80 and the rearrangement reaction device 90, wherein the side wall of the oximation reactor 10 is provided with a feed port 11, and the feed port 11 is connected There is a micro-interface generator 100 for dispersing and crushing gas into bubbles. Specifically, the micro-interface generator 100 is a pneumatic micro-interface generator. The ammonia gas enters the pneumatic micro-interface generator and is broken by the pneumatic micro-interface generator. The dispersion effect disperses and breaks the ammonia gas into microbubbles, thereby reducing the thickness of the liquid film, effectively increasing the mass transfer area between the ammonia gas and the liquid phase material, reducing the mass transfer resistance, and improving the reaction efficiency.

An external circulation device is provided outside the oximation reactor 10 to control the temperature inside the oximation reactor 10. One end of the external circulation device is connected to the side wall of the oximation reactor 10, and the other end is connected to the micro-interface generator 100; The bottom of the oximation reactor 10 is connected to the reaction clear liquid buffer tank 20. As a preference, an external filter device 110 is provided on the connecting pipe between the reaction clear liquid buffer tank 20 and the discharge port 11 to prevent the inside of the oximation reactor 10 After the filter is clogged, the catalyst enters the reaction clear liquid buffer tank 20. The material from the reaction clear liquid buffer tank 20 is introduced from the middle section of the tert-butanol recovery tower 30 for the recovery of tert-butanol. Specifically, the middle section of the tert-butanol recovery tower 30 is provided with a liquid inlet 31 and a gas inlet 32 respectively. The liquid inlet 31 is connected to the bottom of the reaction clear liquid buffer tank 20; the gas inlet 32 is connected to the top of the reaction clear liquid buffer tank 20. The reason why the gas inlet 32 and the liquid inlet 31 are provided at the same time is because the reaction clear liquid buffer tank is The material composition of t-butanol is more complicated. Most of the tert-butanol exists in liquid form, and a small amount is present in the reaction product in gaseous form. In this way, the dual material inlet of gas inlet and liquid inlet can ensure the full recovery and utilization of tert-butanol.

Further, the top of the tert-butanol recovery tower 30 is preferably connected to the tert-butanol reflux tank 120 through two overhead condensers, and a reflux pipeline is also provided between the tert-butanol recovery tower 30 and the tert-butanol reflux tank 120 One end of the reflux pipeline is connected to the top of the tert-butanol recovery tower 30, and the other end is connected to the bottom of the tert-butanol reflux tank 120 for returning the substance in the tert-butanol reflux tank 120 to continue separation and purification. Flow, can improve the recovery purity of tert-butanol. In this embodiment, the reaction system further includes a circulating tert-butanol tank 130, the top of the circulating tert-butanol tank 130 is connected to the bottom of the tert-butanol reflux tank 120, and the bottom of the circulating tert-butanol tank 130 is connected to the oximation reactor 10. A small part of the condensate in the tert-butanol reflux tank 120 is used for reflux at the top of the tower, and most of the remaining part is recycled into the oximation reactor 10 through the circulating tert-butanol tank 130 to be reused as a reaction solvent, reducing the t-butanol The cost of use.

The bottom of the tert-butanol recovery tower 30 of this embodiment is provided with an oxime aqueous solution outlet 33, and the extraction tank 40 is provided with a liquid inlet 41, a light phase outlet 42 and an aqueous phase outlet 43, and the liquid inlet 41 and the oxime aqueous solution The outlet 33 is connected, the light phase discharge port 42 is connected with the water washing separator 50 for washing the toluene oxime solution, and the water phase discharge port 43 is connected with the water extraction tower 140 for extracting and recovering the oxime in the water phase.

In this embodiment, the bottom of the water washing separator 50 is provided with a washing water circulation pipe for returning the washing water to the water washing separator 50 for washing and purification again. By setting the washing water circulation pipe, the washing water can be passed through the washing water circulation pipe. Return to the water washing separator for multiple washing and purification, so as to avoid the waste of toluoxime. A recovery pipeline is also provided between the middle of the washing water circulation pipeline and the top of the water extraction tower 140. The recovery pipeline is used to combine the washing water from the washing water circulation pipeline with the oxime-containing water from the water phase outlet 43. The water extraction tower 140 is passed into the water extraction tower 140 for multi-stage extraction to recover the oxime in the water phase. The water extraction tower 140 is also connected with an extraction liquid receiving tank 170, and the organic phase extracted from the top of the water extraction tower 140 overflows to the extraction liquid receiving tank. 170, and then return to the toluene oxime extraction system through the transfer pump for extraction and water washing, thereby avoiding the waste of cyclohexanone oxime.

In addition, the reaction system of this embodiment also includes a pre-filter 150 and a coalescer 160 that are connected in sequence. The pre-filter 150 is connected to the top of the water-washing separator 50 to enter the coalescer 160 after pre-filtration of toluene oxime. The impurities are separated in the water to complete the washing. After washing with water, the toluoxime enters the pre-filter 150 for filtration, and then enters the coalescer 160 to further separate and purify impurities, and finally the toluoxime with a qualified concentration is sent to the toluoxime storage tank 60.

A first inlet 71 is provided in the middle of the side wall of the first rectification tower 70, a first outlet 72 is provided at the bottom, a second inlet 81 is provided on the side wall of the second rectification tower 80, and a second outlet 82 is provided at the bottom. , The first inlet 71 is connected with the top of the toluoxime storage tank 60 for standing and cooling before the toluoxime rectification, the first outlet 72 is connected with the second inlet 81, and the second outlet 82 is connected with the rearrangement reaction device 90 For the rearrangement reaction, a heater 190 is installed on the pipe between the toluoxime storage tank 60 and the first inlet 71. Specifically, the first rectification tower 70 is composed of a rectification section and a stripping section. Preferably, the stripping section adopts a tray structure, and the rectification section adopts a packing structure, because the pressure drop of the tray itself is relatively large, and the packing The pressure drop is relatively small; the 70 top of the first distillation column is provided with a first top condenser 710, the first top condenser 710 is connected with the first receiving tank 720, the first receiving tank 720 is connected to the first The side walls of the rectification tower 70 are connected for reflux at the top of the tower; the second rectification tower 80 is composed of a stripping section. Preferably, the stripping section adopts a packing structure, and the type of packing is Pall ring packing. The characteristics of large production capacity, strong resistance, large operating flexibility, etc.; the top of the second rectification tower 80 is provided with a second top condenser 810, the second top condenser 810 is connected with the second receiving tank 820, and the second receiving The tank 820 is connected to the toluene deoxime tower 180 for separating toluene and oxime. Both the first distillation tower 70 and the second distillation tower 80 are equipped with vacuuming devices to ensure that the distillation towers are operated under vacuum conditions. It is understandable that the vacuuming devices are not specifically limited here, as long as they can be vacuumed. .

In addition, the pipeline between the second outlet 82 and the rearrangement reaction device 90 is also provided with an oxime cooler 200 and an oxime buffer tank 210 connected in sequence for cooling before the cyclohexanone oxime undergoes the rearrangement reaction. The cooler 200 is connected to the second outlet 82, and the oxime buffer tank 210 is connected to the rearrangement reaction device. Since the rearrangement reaction is a strong exothermic reaction, the cyclohexanone oxime is cooled to a certain temperature before the rearrangement reaction and then enters the rearrangement reaction device 90. The oxime cooler 200 is a shell-and-tube cooler. The type of cooler is simple in structure, low in cost, wide in circulation cross-section, and easy to clean scale.

In this embodiment, the rearrangement reaction device 90 includes a first-stage rearrangement tank 91, a second-stage rearrangement tank 92, and a third-stage rearrangement tank 93 connected in series in sequence; the first-stage rearrangement tank 91, the second-stage rearrangement tank 92 and the third The top of the stage rearrangement tank 93 is connected to the second outlet 82 by pipes. It is understandable that the rearrangement reaction device 90 may also be provided with multiple rearrangement tanks connected in series to form a multi-stage continuous rearrangement reaction, and the tops of multiple rearrangement tanks connected in series may be connected to the second outlet. The multi-stage continuous rearrangement reaction can shorten the reaction time of each stage rearrangement reaction, reduce the occurrence of side reactions in the rearrangement process, and increase the yield of the product.

Further, the first-stage rearrangement tank 91, the second-stage rearrangement tank 92, and the third-stage rearrangement tank 93 are all provided with a rearrangement liquid circulation pipeline to control the temperature in the tank, and the material from the previous-stage rearrangement tank Connect to the rearrangement liquid circulation pipeline of the rearrangement tank of the next stage. Because the Beckman rearrangement reaction is an exothermic reaction, the higher the temperature during the reaction, a series of side reactions will occur under acidic conditions, and the by-product ammonium sulfate will increase greatly, which affects the purity of caprolactam, so it is necessary to set the rearrangement The liquid circulation pipeline uses the circulation heat of the circulation pipeline to derive the reaction heat, thereby effectively smoothing the reaction and reducing the temperature of the reaction in the tank.

Specifically, a rearrangement circulation pump 910, a rearrangement heat exchanger 920 and a three-way valve 930 are provided on the rearrangement liquid circulation pipeline; the three-way valve 930 is located between the rearrangement circulation pump 910 and the rearrangement heat exchanger 920 ; A bypass channel is provided in communication with the three-way valve 930, and the bypass channel is used for working conditions without heat exchange. In the initial stage of the rearrangement reaction, the temperature is relatively low. The reaction liquid enters the rearrangement tank from the bypass channel to carry out the rearrangement reaction. As the reaction progresses, a large amount of heat is released. The generated heat is removed, and then circulated into the rearrangement reaction tank to perform the rearrangement reaction to form a rearrangement liquid circulation pipeline to maintain the reaction temperature in the rearrangement tank within a certain range. The rearrangement heat exchanger 920 is preferably a plate heat exchanger. Compared with other heat exchangers, the plate heat exchanger has the characteristics of high heat exchange efficiency, low heat loss, high efficiency and energy saving, easy cleaning and convenient disassembly.

In the above embodiment, the top of the oximation reactor 10 is also provided with a tail gas outlet 12, the tail gas outlet 12 is connected to a tail gas absorption tower 220, the bottom of the tail gas absorption tower 220 is also provided with an absorption liquid outlet 221, and the absorption liquid outlet 221 is connected to the oximation reaction. The vessel 10 is used for returning the absorption liquid to the oximation reactor for utilization. The tert-butanol reflux tank 120 is provided with a non-condensable gas outlet 121, and the non-condensable gas in the tert-butanol reflux tank 120 is mixed with the tail gas through the non-condensable gas outlet 121 and then enters the tail gas absorption tower 220 for recycling.

The following briefly describes the working process and principle of the external micro-interface ammoximation reaction system of the present invention.

The ammonia gas is introduced into the micro-interface generator 100 before the oximation reactor, and it is broken into micro-bubbles with a diameter of micrometers. The broken micro-bubbles are fully emulsified with the liquid-phase mixed raw materials, effectively increasing The mass transfer area of the gas-liquid two-phase is enlarged, and the mass transfer resistance is reduced.

As the fully emulsified emulsion enters the oximation reactor 10, the oximation reaction is carried out under the action of the catalyst. The temperature in the oximation reactor 10 is 80-84°C and the pressure is 0.19-0.22 MPa. Among them, the ammoximation reaction is a strongly exothermic reaction, and an external circulation device is provided outside the oximation reactor 10 to control the temperature inside the reactor.

During the reaction process, unreacted ammonia, alcohol and other gases are cooled from the tail gas outlet 12 and then enter the tail gas absorption tower 220. The tail gas absorption tower 220 uses desalinated water to absorb the ammonia and alcohol therein to become an absorption liquid. After the absorption liquid outlet 221 comes out, it enters the oximation reactor 10 for repeated recycling. The oximation reaction product (cyclohexanone oxime, ammonia and a small amount of tert-butanol, etc.) enters the reaction clear liquid buffer tank 20 as a clear liquid, and then enters through the liquid inlet 31 and the gas inlet 32 of the tert-butanol recovery tower 30 respectively. The tert-butanol is recovered in the tower. The mixed fraction of water, ammonia, and tert-butanol steamed from the top of the tert-butanol recovery tower 30 is cooled by the condenser at the top of the tower and then enters the tert-butanol reflux tank 120. The uncooled non-condensable gas is mixed with the tail gas of the oximation reactor 10 through the non-condensable gas outlet 121 and then enters the tail gas absorption tower 220 for ammonia recovery. A small part of the condensate in the tert-butanol reflux tank 120 is used for reflux at the top of the tower, and most of the remaining part is recycled into the oximation reactor 10 through the circulating tert-butanol tank 130 to be reused as a reaction solvent, which reduces the use cost of tert-butanol. .

The oxime aqueous solution exits from the oxime aqueous solution outlet 33 of the tert-butanol tower 30 and then enters the extraction tank 40 after being cooled to a certain temperature. The oxime is extracted from the oxime aqueous solution into the toluene phase by using the solubility of toluene to oxime to realize the oxime Separation from water. The toluene oxime solution exits the light phase outlet 42 of the extraction tank 40 and enters the water washing separator 50, is washed with desalinated water, filtered through the pre-filter 150, and then enters the coalescer 160 for further separation and purification of impurities. The concentration of toluoxime is sent to the toluoxime storage tank 60. Among them, the washing water 0 containing about 1% of oxime and a small amount of dissolved toluene is combined with the oxime-containing water from the water phase outlet 43 and then passed into the water extraction tower 140 for multi-stage extraction, thereby recovering the oxime in the water phase. .

The toluene oxime in the toluene oxime storage tank 60 is heated by the heater 190 and enters the first rectification tower 70 from the first inlet 71. The top of the first rectification tower 70 recovers toluene that does not contain oxime, and the bottom of the tower contains a small amount of toluene. The oxime solution of toluene exits from the first outlet 72 and enters the second rectification tower 80 through the second inlet 81. Toluene containing a small amount of oxime is evaporated from the top of the second rectification tower 80, and the cyclohexanone oxime in the bottom of the tower passes through The second outlet 82 is cooled by the oxime cooler 200 and then enters the oxime buffer tank 210.

The cyclohexanone oxime in the oxime buffer tank 210 enters the first-stage rearrangement tank 91, the second-stage rearrangement tank 92 and the third-stage rearrangement tank 93 according to a certain proportion. In the presence of fuming sulfuric acid, the cyclohexanone oxime passes through the Baker Mann molecular rearrangement is converted into caprolactam. The first-stage rearrangement liquid in the first-stage rearrangement tank 91 overflows from the upper part of the tank and mixes with the bottom material of the second-stage rearrangement tank 92, then enters the second-stage rearrangement tank 92 and newly added The cyclohexanone oxime reaction; the secondary rearrangement liquid in the secondary rearrangement tank 92 overflows from the upper part of the tank and mixes with the bottom material of the tertiary rearrangement tank 93, then enters the tertiary rearrangement tank 93 and the newly added The cyclohexanone oxime reacts, and the final product overflows from the upper part of the three-stage rearrangement tank 93 for collection.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, but not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that it is still The technical solutions recorded in the foregoing embodiments may be modified, or some or all of the technical features may be equivalently replaced; these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention .

Claims

[Cited and added (Rule 20.6) 28.06.2020]
1. An external micro-interface ammoximation reaction system, characterized in that it comprises an oximation reactor, a reaction clear liquid buffer tank, a tert-butanol recovery tower, an extraction tank, a water washing separator, a toluoxime storage tank, and a first The rectification tower, the second rectification tower and the rearrangement reaction device, wherein the side wall of the oximation reactor is provided with a feed port, and the feed port is connected with a micro-interface generator for dispersing broken gas into bubbles An external circulation device is provided outside the oximation reactor to control the temperature inside the oximation reactor, one end of the external circulation device is connected to the side wall of the oximation reactor, and the other end is connected to the The micro-interface generator is connected; the bottom of the oximation reactor is connected to the reaction clear liquid buffer tank, and the material from the reaction clear liquid buffer tank is passed through the middle section of the tert-butanol recovery tower for use The recovery of tert-butanol; the extraction tank is provided with a liquid inlet and a light phase outlet, the liquid inlet is connected to the bottom of the tert-butanol recovery tower, and the light phase outlet is connected to the water washing The separator is connected for water washing of the toluene oxime solution; the toluoxime that has passed the water washing of the water washing separator enters the toluoxime storage tank, and the middle of the side wall of the first rectification tower is provided with a first inlet , A first outlet is provided at the bottom, a second inlet is provided on the side wall of the second rectification tower, and a second outlet is provided at the bottom. The first inlet is connected to the top of the toluene oxime storage tank for use Before the toluene oxime rectification, the first outlet is connected to the second inlet, and the second outlet is connected to the rearrangement reaction device to perform a rearrangement reaction.
2. The external micro-interface ammoximation reaction system according to claim 1, wherein the micro-interface generator is a pneumatic micro-interface generator, and the number of micro-interface generators is at least one.
3. The external micro-interface ammoximation reaction system according to claim 1, wherein the rearrangement reaction device comprises a first-stage rearrangement tank, a second-stage rearrangement tank and a third-stage rearrangement tank connected in series in sequence The tops of the one-stage rearrangement tank, the second-stage rearrangement tank and the third-stage rearrangement tank are all connected to the second outlet through a pipe.
4. The external micro-interface ammoximation reaction system according to claim 3, wherein the first-stage rearrangement tank, the second-stage rearrangement tank and the third-stage rearrangement tank are all provided with a rearrangement liquid circulation pipeline To control the temperature in the tank, the material from the rearrangement tank of the previous stage is connected to the rearrangement liquid circulation pipeline of the rearrangement tank of the next stage.
5. The external micro-interface ammoximation reaction system according to claim 4, wherein the rearrangement liquid circulation pipeline is provided with a rearrangement circulation pump, a rearrangement heat exchanger and a three-way valve, so The three-way valve is located between the rearrangement circulation pump and the rearrangement heat exchanger; a bypass channel is provided in communication with the three-way valve, and the bypass channel is used for working conditions without heat exchange.
6. The external micro-interface ammoximation reaction system according to claim 1, wherein the pipe between the second outlet and the rearrangement reaction device is provided with an oxime cooler and an oxime that are connected in sequence. The buffer tank is used to cool the cyclohexanone oxime before the rearrangement reaction, the oxime cooler is connected to the second outlet, and the oxime buffer tank is connected to the rearrangement reactor.
7. The external micro-interface ammoximation reaction system according to claim 1, wherein the first rectifying tower is composed of a rectifying section and a stripping section, and the second rectifying tower is composed of a stripping section. Segment composition.
8. The external micro-interface ammoximation reaction system according to claim 7, wherein the top of the first distillation column is provided with a first top condenser, and the first top condenser Connected to the first receiving tank, the first receiving tank is connected to the side wall of the first rectification tower by a transfer pump for reflux at the top of the tower; the top of the second rectification tower is provided with a second tower A top condenser, the second tower top condenser is connected to a second receiving tank, and the second receiving tank is connected to a toluene deoximation tower for separating toluene and oxime.
9. The external micro-interface ammoximation reaction system according to claim 1, wherein the first rectification tower and the second rectification tower are both equipped with a vacuum device to ensure that the rectification tower is Operate under vacuum conditions.
10. The external micro-interface ammoximation reaction system according to any one of claims 1-8 is used to carry out the oximation reaction method, which is characterized in that it comprises the following steps: after the ammonia gas is dispersed and broken into microbubbles, it is combined with the liquid phase The material undergoes catalytic oximation reaction; the reaction product is collected as a clear liquid and then recovered by tert-butanol; the oxime aqueous solution after tert-butanol is recovered, and then toluene is extracted and washed; Preferably, the temperature of the oximation reaction is 80-84°C, and the pressure is 0.19-0.22 MPa.