CN211329403U

CN211329403U - Production system provided with venturi tube and used for synthesizing adiponitrile from adipic acid

Info

Publication number: CN211329403U
Application number: CN201922096787.7U
Authority: CN
Inventors: 黄家辉; 张少华
Original assignee: Dalian Institute of Chemical Physics of CAS
Current assignee: Dalian Institute of Chemical Physics of CAS
Priority date: 2019-11-28
Filing date: 2019-11-28
Publication date: 2020-08-25
Anticipated expiration: 2029-11-28

Abstract

The utility model provides a production system for synthesizing adiponitrile by adipic acid, which comprises a raw material preparation kettle, a loop reactor, an external heat exchanger and a product receiving tank; the raw material preparation kettle is provided with a feeding hole and a discharging hole; a Venturi ejector is arranged at the top end inside the loop reactor; the loop reactor is provided with a feed inlet, a discharge outlet, an ammonia inlet and an ammonia outlet; the external heat exchanger is provided with a material inlet and a material outlet; the discharge hole of the raw material preparation kettle is communicated with the feed inlet of the loop reactor through a pipeline; and the discharge hole of the loop reactor is respectively communicated with the material inlet of the external heat exchanger and the product receiving tank through pipelines. The utility model discloses a reaction system equipment is simple, easy operation, and the maintenance cost is low. The Venturi ejector can uniformly mix gas phase and liquid phase, greatly improves the mass transfer efficiency, accelerates the reaction speed and improves the synthesis efficiency of adiponitrile.

Description

Production system provided with venturi tube and used for synthesizing adiponitrile from adipic acid

Technical Field

The utility model belongs to adiponitrile synthesis field, concretely relates to production system of synthetic adiponitrile of adipic acid with venturi.

Background

An adipic acid ammoniation method is an important method for preparing adiponitrile, and the process flow is that adipic acid and a large amount of ammonia gas are sent into an adiponitrile reactor in the presence of a catalyst (phosphoric acid is commonly used as the catalyst), neutralization reaction is carried out at the temperature of 250-300 ℃ to generate diammonium adipate, and then dehydration reaction is carried out to generate adiponitrile. In the existing nitrile reactor, generally, a gas material is directly bubbled after being sent out from a central pipe, and a large amount of gas flows out from an intermediate pipeline, so that gas-phase flow is concentrated, the gas-phase and liquid-phase contact is insufficient, and the bubbling efficiency and the reaction yield are low. The lower yield can further cause a large amount of by-products to be generated in the reaction process, so that the coking in the reactor is serious, the mass transfer efficiency in the tube array of the reactor is reduced, the heat transfer speed is reduced, and the operation period of the reactor is finally seriously influenced.

The liquid phase method adipic acid catalytic ammoniation reaction is generally carried out by introducing excessive ammonia gas into molten adipic acid and reacting under the catalytic action of phosphoric acid. The neutralization of adipic acid with ammonia is exothermic, but the dehydration of diammonium adipate is strongly endothermic, and therefore most of the patents use tubular heating. Although the high temperature is beneficial to the dehydration reaction of the diammonium adipate, the energy consumption is increased, and the liquid-gas ratio of the reactor heating tube array is higher, so that the heating tube array is coked. In order to slow down coking, the disclosed technical measures include adding a series bubble pre-reaction section (high peak-like chemical reaction engineering and process 1992,8(2): 194); circulation between the reactor and the subsequent separation column liquid stream (lijing first-class CN 201210577924.9); the separation tower liquid further adopts a semi-nitrile evaporator to remove tar, so that the stability of the system operation is improved (CN 204265662u of Wenju et al, CN204147575u of Jiangzhong et al). The two-stage method applied to the ammonification of adipic acid can partially reduce coking (CN201210577924.9) in the ammonification process, but can increase the decomposition of adipic acid, thereby reducing the yield of products. In addition, the neutralization and dehydration reactions are reversible, and the dehydration of the intermediate by-product Iminonitrilylcyclopentane (ICCP) to adiponitrile is severely affected by the high water content in the vapor phase (Peak et al chemical engineering and Processes 1991,7(2): 128).

SUMMERY OF THE UTILITY MODEL

The utility model aims to solve the technical problem that a material intensive mixing is provided, area of contact is big, and heat transfer speed is fast, material misce bene to can reduce tubulation inner wall coking and material deposit's adiponitrile production system.

The utility model provides a technical scheme that above-mentioned technical problem adopted does:

the utility model provides a production system for synthesizing adiponitrile by adipic acid, which comprises a raw material preparation kettle, a loop reactor, an external heat exchanger and a product receiving tank; the raw material preparation kettle is provided with a feeding hole and a discharging hole; a Venturi ejector is arranged at the top end inside the loop reactor; the loop reactor is provided with a feed inlet, a discharge outlet, a material circulation port, an ammonia inlet and an ammonia outlet; the external heat exchanger is provided with a material inlet and a material outlet; the discharge hole of the raw material preparation kettle is communicated with the feed inlet of the loop reactor through a pipeline; the discharge hole of the loop reactor is respectively communicated with the material inlet of the external heat exchanger and the product receiving tank through pipelines; and a discharge hole of the external heat exchanger is communicated with a material circulation hole of the loop reactor.

Based on the technical scheme, preferably, the outer walls of the shells of the raw material preparation kettle and the loop reactor are provided with external heat-insulating jackets, the heat-insulating jackets contain heat-conducting oil, and the temperature of the raw material preparation kettle and the temperature of the loop reactor are controlled through circulation of the heat-conducting oil.

Based on the above technical solution, preferably, the production system further includes an external heat exchanger including three parts: the circulator, the heater, the cooler and the external heat exchanger comprise a material circulating pipeline and a heat conducting oil circulating pipeline, and the heat conducting oil circulating pipeline is used for realizing the temperature control of the whole system.

Based on the technical scheme, preferably, the raw material preparation kettle is provided with a stirring part.

Based on the technical scheme, preferably, the feed inlets of the raw material preparation kettle comprise a catalyst feed inlet, an adipic acid feed inlet and an adiponitrile feed inlet. Adipic acid, adiponitrile and catalyst phosphoric acid are uniformly mixed in a raw material preparation kettle and then are conveyed into a loop reactor through a feed pump. The loop reactor is provided with an ammonia gas inlet and an ammonia gas outlet, so that the ammonia gas is continuously introduced into the reactor. The liquid reacted in the reactor is transferred to the product receiving tank by the circulation pump.

Based on the technical scheme, preferably, the Venturi ejector comprises a gas inlet, a liquid inlet, a nozzle, a gas suction cavity, a liquid jet zone, a mixing impact zone, a diffusion zone and a drainage tube; the gas inlet is communicated with an ammonia gas injection port of the loop reactor, and the liquid inlet is communicated with a material circulation port of the loop reactor; and a material outlet of the external heat exchanger is communicated with a material circulating port of the loop reactor. The raw material pump conveys materials in the raw material preparation kettle to the loop reactor through a feed inlet of the loop reactor, the materials in the loop reactor are conveyed to the external heat exchanger for heat exchange through a circulating pump, the materials enter a Venturi ejector of the loop reactor through a material outlet of the external heat exchanger and a circulating material port of the loop reactor, the materials are conveyed to a nozzle through a liquid inlet of the Venturi ejector, a quick jet flow is formed through the nozzle to carry gas in a gas chamber to be ejected, the liquid is impacted on a pipe wall to be uniformly dispersed and then fully mixed with the gas, foam is well diffused in a diffusion region through turbulence formed by mutual collision of the liquid and the gas, the mixture is separated from the mixing ejector at the bottom of the diffuser through a drainage pipe, and circulation is realized in the loop reactor.

Based on the technical scheme, preferably, the loop reactor is provided with a gas phase temperature monitoring port and a liquid phase temperature monitoring port.

Based on the technical scheme, preferably, a raw material feeding pump is arranged between the raw material preparation kettle and the loop reactor; and a circulating pump is arranged between the loop reactor and the product receiving tank or the external heat exchanger, and the reaction materials in the loop reactor control the circulating flow through the circulating pump.

Based on the technical scheme, preferably, sampling ports are arranged on pipelines of the loop reactor and the product receiving tank.

Based on the technical scheme, preferably, the pipelines entering the raw material preparation kettle, the loop reactor, the external heat exchanger and the product receiving tank are all provided with stop valves, wherein a stop valve I is arranged between the circulating pump and the external heat exchanger; be equipped with stop valve II between circulating pump and the product receiving tank, when needs reaction material is reacted at loop reactor and external heat exchanger circulation, close stop valve II, open stop valve I, when needs stop reaction, when receiving the product, close stop valve I, open stop valve II.

Advantageous effects

(1) The utility model discloses a reaction system equipment is simple, easy operation, and the maintenance cost is low. The Venturi ejector can uniformly mix gas phase and liquid phase, greatly improves the mass transfer efficiency, accelerates the reaction speed and improves the synthesis efficiency of adiponitrile.

(2) The utility model discloses the loop reactor of system makes material area of contact grow, and the heat transfer is fast, and the heat transfer is more even to can reduce tubulation inner wall coking and material deposit.

Drawings

FIG. 1 is a schematic diagram of the system of the present invention;

FIG. 2 is a schematic diagram of a venturi jet mixer of the system of the present invention;

wherein: 1. a raw material preparation kettle; 2. a loop reactor; 3. an external heat exchanger; 4. a product receiving tank; 5. a feed pump; 6. a circulation pump; 7. a heat-preserving jacket; 8. a sampling port; 1-I, adipic acid and adiponitrile feed inlets; 1-II, a catalyst feed port; 2-I, a Venturi ejector; 2-II, a liquid phase temperature monitoring port; 2-III, a gas phase temperature monitoring port; 2-IV and an ammonia gas inlet; 2-V, ammonia gas flow meter; 2-VI and a feed inlet; 2-VII, a discharge hole; 2-VIII, a material circulation port; 2-I-a, a liquid inlet; 2-i-b, a gas inlet; 2-I-c, a nozzle; 2-i-d, a gas intake chamber; 2-i-e, liquid jet; 2-i-f, mixed impingement zone; 2-i-g, diffusion region; 2-I-h and a drainage tube.

Detailed Description

The adiponitrile production system adopts a loop reactor, and comprises a raw material preparation kettle 1, a feeding pump 5, a loop reactor 2, an external heat exchange 3, a circulating pump 6, a product receiving tank 4 and a gas system, wherein the gas system is an ammonia gas conveying system, and preheated ammonia gas is conveyed to ammonia gas inlets 2-IV of the loop reactor 2 through ammonia gas flowmeters 2-V. Adipic acid and adiponitrile enter a raw material preparation kettle 1 through an adipic acid and adiponitrile feeding hole 1-I; catalyst phosphoric acid enters a raw material preparation kettle 1 through a catalyst feeding port 1-II, and materials in the raw material preparation kettle 1 are conveyed to a loop reactor through a feeding port 2-VI of the loop reactor through a feeding pump 5; the top end in the loop reactor is provided with a Venturi ejector 2-I which adopts a structure with a narrow top and a wide bottom. Liquid raw materials such as adiponitrile and the like entering through the material circulation ports 2-VIII are sucked by utilizing the negative pressure formed by ammonia gas at the Venturi ejector, so that the gas and the liquid materials are fully mixed and dispersed and are sprayed into the reaction tank. The adiponitrile synthesis reaction is safely and stably carried out continuously by a circulating pump. The outer sides of the tank body of the loop reactor 2 and the raw material preparation tank 1 are provided with a heat-insulating jacket 7, and heat-conducting oil is filled in the heat-insulating jacket 7 and used for controlling the temperature; a tank body of the loop reactor 2 is also provided with a gas phase temperature monitoring port 2-III and a liquid phase temperature monitoring port 2-II; the input end of the circulating pump 6 is connected with the discharge ports 2-VII of the loop reactor; the output end of the circulating pump is connected with a material circulating port at the top of the loop reactor through a discharge port 2-VII of the external heat exchanger, and a liquid inlet and a gas inlet are connected on the Venturi ejector. The liquid carries gas after being sprayed, and the reaction system is continuously operated all the time through a circulating pump. And after the reaction is finished, collecting the product into a product receiving tank, performing subsequent product separation, and arranging a sampling port 8 on a pipeline of the product coming out of the outlet of the loop reactor before entering the product receiving tank for sampling test.

Example l

First, 100kg/h of adipic acid, 200kg/h of adiponitrile and 0.5kg/h of phosphoric acid catalyst were added to a premix pot and preheated to 170 ℃. After the temperature is reached, adding the materials into a loop reactor, opening a circulating pump, and introducing ammonia gas from an ammonia gas inlet, wherein the flow rate of the ammonia gas is 100 kg/h. The negative pressure formed by the material circulation at the nozzle of the Venturi ejector is utilized to ensure that the mixed raw material liquid and gas are uniformly introduced and well dispersed. The temperature of the loop reactor was controlled at 260 ℃ by an external heat exchanger during the reaction. The device can continuously and uniformly feed raw materials in proportion, and finished products are continuously taken out from the pipeline opening. The raw materials are continuously fed into the loop reactor at a speed of 1L/min, and the retention time of the materials in the reactor is ensured to be 60 min. The analysis result by gas chromatography showed that the yield of adiponitrile as the final product was 85%, the dehydration rate of adipic acid was 89.6%, and the amount of carbon deposition was 0.39%.

Example 2

Firstly, 100kg/h of adipic acid, 200kg/h of adiponitrile and 0.5kg/h of phosphoric acid catalyst are added into a raw material preparation kettle, and the raw material preparation kettle is preheated to 180 ℃. After the temperature is reached, adding the materials into a loop reactor, opening a circulating pump, and introducing ammonia gas from an ammonia gas inlet, wherein the flow rate of the ammonia gas is 100 kg/h. The negative pressure formed by the material circulation at the venturi ejector nozzle is utilized to ensure that the liquid and the gas are uniformly introduced and well dispersed. The temperature of the reactor is controlled to be 280 ℃ by an external heat exchanger in the reaction process. The device can continuously and uniformly feed raw materials in proportion, and finished products are continuously taken out from the pipeline opening. The raw materials are continuously fed into a loop reactor at a speed of 1L/min, and the retention time of the materials in the reactor is ensured to be 60 min. The analysis result by gas chromatography showed that the yield of adiponitrile as the final product was 90%, the dehydration rate of adipic acid was 93.5%, and the amount of carbon on the reactor surface was 0.31%.

Comparative example 1

Firstly, 100kg/h of adipic acid, 200kg/h of adiponitrile and 0.5kg/h of phosphoric acid catalyst are premixed through a mixer, conveyed into a cyanation reactor through a feed pump, reacted with fresh ammonia gas (the flow rate of the ammonia gas is 100kg/h), and the materials are reacted at 280 ℃, and the adipic acid is dehydrated under the temperature regulation to generate the adiponitrile. This time should add reaction time, otherwise it is difficult to compare. The reaction was carried out at 280 ℃ for 60min and the product was then analysed by gas chromatography. The analysis result showed that the yield of adiponitrile as the final product was 81.2%, the dehydration rate of adipic acid was 85.8%, and the amount of carbon deposition was 0.74%.

Claims

1. A production system for synthesizing adiponitrile by using adipic acid is characterized by comprising a raw material preparation kettle, a loop reactor, an external heat exchanger and a product receiving tank; the raw material preparation kettle is provided with a feeding hole and a discharging hole; a Venturi ejector is arranged at the top end inside the loop reactor; the loop reactor is provided with a feed inlet, a discharge outlet, a material circulation port, an ammonia inlet and an ammonia outlet; the external heat exchanger is provided with a material inlet and a material outlet; the discharge hole of the raw material preparation kettle is communicated with the feed inlet of the loop reactor through a pipeline; the discharge hole of the loop reactor is respectively communicated with the material inlet of the external heat exchanger and the product receiving tank through pipelines; and a discharge hole of the external heat exchanger is communicated with a material circulation hole of the loop reactor.

2. The production system according to claim 1, wherein: the external heat-insulating jacket is arranged on the outer wall of the shell of the raw material preparation kettle and the shell of the loop reactor, the heat-insulating jacket contains heat-conducting oil, and the temperature of the raw material preparation kettle and the temperature of the loop reactor are controlled through circulation of the heat-conducting oil of the external heat exchanger.

3. The production system of claim 2, further comprising an external heat exchanger comprising a circulator, a heater, and a cooler.

4. The production system of claim 1, wherein the raw material compounding kettle is provided with a stirring member.

5. The production system of claim 1, wherein the feedstock preparation kettle feed ports comprise a catalyst feed port, an adipic acid feed port, and an adiponitrile feed port.

6. The production system of claim 1, wherein the venturi ejector comprises a gas inlet, a liquid inlet, a nozzle, a gas suction chamber, a liquid jet zone, a mixing impingement zone, a diffusion zone, and a draft tube; the gas inlet is communicated with an ammonia gas injection port of the loop reactor, and the liquid inlet is communicated with a material circulation port of the loop reactor.

7. The production system of claim 1, wherein the loop reactor is provided with a gas phase temperature monitoring port and a liquid phase temperature monitoring port.

8. The production system of claim 1, wherein a feed pump is disposed between the feed preparation tank and the loop reactor; a circulating pump is arranged between the loop reactor and the product receiving tank or the external heat exchanger.

9. The production system of claim 1, wherein the piping of the loop reactor and the product receiving tank are provided with sampling ports.

10. The production system of claim 8, wherein a stop valve I is arranged between the circulating pump and the external heat exchanger; and a stop valve II is arranged between the circulating pump and the product receiving tank.