WO2021253312A1

WO2021253312A1 - Enhanced reaction system and method for preparing polypropylene by means of slurry process

Info

Publication number: WO2021253312A1
Application number: PCT/CN2020/096739
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: 2020-06-17
Filing date: 2020-06-18
Publication date: 2021-12-23
Also published as: CN111892672A

Abstract

An enhanced reaction system and method for preparing polypropylene by means of a slurry process. The enhanced reaction system comprises: a prepolymerization reactor (10) and a polymerization reactor (20), which are connected in order. The prepolymerization reactor (10) is provided with a prepolymerization micro-interface generator (101) used for dispersing and crushing a material into micro-bubbles, and the polymerization reactor (20) is provided with a micro-interface generator set. A polymerization reaction product outlet (2020) is provided at the bottom of the polymerization reactor (20), and the polymerization reaction product outlet (2020) is connected to a flash tank (40) for flash evaporation of the polymerization reaction product. A first gas phase outlet (4010) is provided at the top of the flash tank (40), and a material discharged from the first gas phase outlet (4010) is introduced into a pre-washing tower (50) for washing and impurity removal. By means of the arrangement of the prepolymerization micro-interface generator (101) on the prepolymerization reactor (10), and also by means of the arrangement of the micro-interface generator set on the polymerization reactor (20), the mass transfer area between a gas phase material and a liquid phase material is increased, the reaction efficiency is improved, and the energy consumption is reduced; in addition, the temperature and pressure inside the polymerization reactor (20) are reduced, and the safety and stability of the whole system are improved.

Description

Intensified reaction system and method for preparing polypropylene by slurry method

Technical field

The present invention relates to the technical field of preparing polypropylene, in particular, to a reinforced reaction system and method for preparing polypropylene by a slurry method.

Background technique

Polypropylene is one of the most promising thermoplastic polymer materials today. Compared with other general thermoplastic polymer materials, it has low price, low specific gravity, excellent yield strength, tensile strength and other mechanical properties. Stress crack resistance and wear resistance, good chemical stability, easy forming and processing, excellent comprehensive physical and mechanical properties, wide application range, etc. In addition, polypropylene has abundant raw materials and low prices. With the emergence of new high-efficiency catalysts, the production process is continuously simplified and the cost is continuously reduced. These are all favored by people and have been widely used in chemicals, electrical appliances, automobiles, construction, packaging, etc. The industry is expanding to the application fields of coatings, adhesives, inks, plastics, fibers and other thermoplastics, engineering plastics, and even metals. Over the past few decades, there have been more than 20 technological routes for the production of polypropylene. Various technological routes can be divided into solution method, slurry method (also called solvent method), bulk method, bulk and gas-phase combined method according to the type of polymerization. Gas phase production process. Among them, the products produced by the slurry method are more popular than other polymerization technology, and compared with other propylene polymerization technology methods, the slurry method has milder reaction conditions and can produce products with stable quality and superior performance. This method has low polymerization pressure. , The device is easy to operate, and the equipment is easy to maintain.

The slurry method usually uses stirred bed reactors, tank reactors, tubular reactors, tower reactors, etc. as polymerization reactors, but the phase boundary area and mass transfer coefficient provided by it are limited, and the gas utilization rate is low, resulting in reaction efficiency. The reaction performance is relatively low, so it is difficult to achieve a breakthrough improvement in the reaction performance, which affects the overall efficiency of the reaction; in addition, there is a reaction peak in the initial stage of propylene polymerization, with large heat release, intense heat generation, and excessively high internal temperature and pressure in the reactor. This leads to high energy consumption and low reaction efficiency in the reaction process, and at the same time reduces the safety and stability of the entire system.

In view of this, the present invention is proposed.

Summary of the invention

The first object of the present invention is to provide an enhanced reaction system for preparing polypropylene by a slurry method. , On the one hand, the material can be dispersed and broken into microbubbles, thereby increasing the area of the phase boundary between the gas phase and the liquid phase, so that the mass transfer space is fully satisfied, and the residence time of the gas in the liquid phase is increased, thereby reducing the gas consumption , Reducing energy consumption; on the other hand, at the same time, reducing the internal operating temperature and pressure of the polymerization reactor, improving the safety and stability of the entire reaction system.

The second object of the present invention is to provide a method for preparing polypropylene by adopting the above-mentioned intensified reaction system slurry method, which is beneficial to reduce energy consumption and achieve 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 enhanced reaction system for preparing polypropylene by a slurry method, comprising: a pre-polymerization reactor and a polymerization reactor connected in sequence. Interface generator, said polymerization reactor is provided with a micro-interface generating unit for dispersing crushed materials into micro-bubbles;

A polymerization reaction product outlet is provided at the bottom of the polymer reactor, and the polymerization reaction product outlet is connected to a flash tank for flashing the product after the polymerization reaction; the top of the flash tank is provided with a first gas phase outlet , The material from the first gas phase outlet is passed into the pre-washing tower for washing and removing impurities; the bottom of the pre-washing tower is provided with a solid phase outlet, and the material from the solid phase outlet is passed into the bag filter to separate polypropylene Powder; the bottom of the flash tank is provided with a product outlet for the discharge of polypropylene products, and the product outlet is connected with a steaming tank for the removal of hydrocarbons in the product.

In the prior art, the reaction system for preparing polypropylene by the slurry method has the following problems: on the one hand, the gas-liquid mass transfer area of the polymerization reactor is limited, the reaction mixture raw materials and the gas cannot be fully mixed during the reaction process, and the energy consumption is large and the reaction is high. The efficiency is low; on the other hand, due to the high temperature and pressure during the reaction, the safety and stability of the entire system cannot be guaranteed. The intensified reaction system for preparing polypropylene by the slurry method of the present invention, by arranging a micro-interface generator on the pre-polymerization reactor and at the same time setting a micro-interface generating unit on the polymerization reactor, on the one hand, the material can be dispersed and broken into micro-bubbles , Thereby increasing the area of the phase boundary between the gas phase and the liquid phase, so that the mass transfer space is fully satisfied, and the residence time of the gas in the liquid phase is increased, thereby reducing gas consumption and energy consumption; on the other hand, at the same time The operating temperature and pressure inside the polymerization reactor are reduced, and the safety and stability of the entire reaction system are improved.

Further, it also includes a propylene delivery pipeline, the pre-polymerization micro-interface generator is arranged inside the pre-polymerization reactor, and the propylene delivery pipeline passes through the wall of the pre-polymerization reactor to connect to the pre-polymerization micro-interface. The generator is used to pass propylene into the interior of the pre-polymerized micro-interface generator. Propylene enters the interior of the pre-polymerized micro-interface generator, and the propylene is dispersed and broken into micro-bubbles through the crushing and dispersion effect of the pre-polymerized micro-interface generator, thereby reducing the thickness of the liquid film and effectively increasing the gap between the propylene and the liquid material. The mass transfer area between them reduces the mass transfer resistance and improves the reaction efficiency.

Further, the micro-interface generator unit includes a first micro-interface generator and a second micro-interface generator, the first micro-interface generator is arranged outside the polymerization reactor, and the second micro-interface generator The first micro-interface generator is arranged inside the polymerization reactor, and the prepolymer obtained by the reaction in the polymerization reactor is passed through the first micro-interface generator.

Further, the bottom of the pre-polymerization reactor is provided with a prepolymer outlet, the side wall of the polymerization reactor is provided with a feed port, and one end of the first micro-interface generator is connected with the feed port, The other end is connected to the outlet of the prepolymer.

Further, the second micro-interface generator is connected with a gas-phase pipeline for recovering gas above the liquid level of the polymerization reactor and a liquid-phase circulation pipeline for powering the second micro-interface generator, and the liquid-phase circulation One end of the pipe is connected with the side wall of the polymerization reactor, and the other end is connected with the second micro-interface generator. During the reaction, a large amount of unreacted propylene accumulates on the top of the reactor. In order to fully recover, it enters the bottom through the gas-phase pipeline for multiple cycles to react, thereby improving the mass transfer efficiency.

Those skilled in the art can understand that the micro-interface generator used in the present invention has been embodied in the inventor’s prior patents, such as application numbers CN201610641119.6, 201610641251.7, CN201710766435.0, CN106187660, CN105903425A, CN109437390A, CN205833127U and CN207581700U patents. The prior patent CN201610641119.6 detailed the specific product structure and working principle of the micro-bubble generator (ie micro-interface generator). It has a cavity, the body is provided with an inlet communicating with the cavity, the opposite first end and the second end of the cavity are both open, and the cross-sectional area of the cavity is from the middle of the cavity to the first end of the cavity and The second end is reduced; the secondary crushing piece is provided at at least one of the first end and the second end of the cavity, a part of the secondary crushing piece is set in the cavity, and the secondary crushing piece is open to both ends of the cavity An annular channel is formed between the through holes. The micro-bubble generator also includes an air inlet pipe and a liquid inlet pipe." From the specific structure disclosed in the application document, it can be known that the specific working principle is: the liquid enters the micron tangentially through the liquid inlet pipe. In the bubble generator, ultra-high-speed rotation and cutting the gas, so that the gas bubbles are broken into micron-level micro-bubbles, thereby increasing the mass transfer area between the liquid phase and the gas phase, and the micro-bubble generator in this patent is a pneumatic micro-interface generation Device.

In addition, in the previous patent 201610641251.7, it is stated that the primary bubble breaker has a circulating liquid inlet, a circulating gas inlet and a gas-liquid mixture outlet. The secondary bubble breaker connects the feed port with the gas-liquid mixture outlet, indicating that the bubble breakers are all It needs to be mixed with gas and liquid. In addition, it can be seen from the following drawings that the primary bubble breaker mainly uses circulating fluid as power, so in fact, the primary bubble breaker belongs to the hydraulic micro-interface generator, and the secondary bubble breaker combines the gas and liquid The mixture is simultaneously passed into the elliptical rotating sphere for rotation, thereby realizing bubble breakage during the rotation, so the secondary bubble breaker is actually a gas-liquid linkage micro-interface generator. In fact, whether it is a hydraulic micro-interface generator or a gas-liquid linkage micro-interface generator, it belongs to a specific form of the micro-interface generator. However, the micro-interface generator used in the present invention is not limited to the above-mentioned forms The specific structure of the bubble breaker described in the previous patent is only one of the forms that the micro-interface generator of the present invention can adopt.

In addition, the previous patent 201710766435.0 records that "the principle of the bubble breaker is high-speed jets to achieve gas collisions", and also explained that it can be used in a micro-interface strengthening reactor, verifying the difference between the bubble breaker and the micro-interface generator. There are also related records in the previous patent CN106187660 about the specific structure of the bubble breaker. For details, see paragraphs [0031]-[0041] in the specification and the attached drawings. The specific working principle of the bubble breaker is explained in detail. The top of the bubble breaker is the liquid phase inlet, and the side is the gas phase inlet. The liquid phase coming in from the top provides the entrainment power to achieve the effect of crushing into ultra-fine bubbles, which can also be seen in the attached drawings. The bubble breaker has a cone-shaped structure, and the diameter of the upper part is larger than that of the lower part, which is also for the liquid phase to provide better entrainment power.

Since the micro-interface generator was just developed at the early stage of the patent application, it was named micro-bubble generator (CN201610641119.6) and bubble breaker (201710766435.0) in the early days. With continuous technological improvement, it was later renamed as micro-interface generator. Now the micro-interface generator in the present invention is equivalent to the previous micro-bubble generator, bubble breaker, etc., but the name is different.

In summary, the micro-interface generator of the present invention belongs to the prior art. Although some bubble breakers are pneumatic bubble breakers, some bubble breakers are hydraulic bubble breakers, and some are pneumatic bubble breakers. Types of liquid-linked bubble breakers, but the difference between the types is mainly selected according to the specific working conditions. In addition, regarding the connection of the micro-interface generator and the reactor, and other equipment, including the connection structure and connection position, according to the micro It depends on the structure of the interface generator, which is not limited.

Further, the bottom of the bag filter is provided with a polypropylene powder outlet, and the polypropylene powder outlet is connected to the steaming tank for removing hydrocarbons in the polypropylene powder. A steam jacket is arranged on the outside of the steaming tank to keep its temperature at about 105°C, which not only ensures that the steam in the steaming tank will not condense, but also ensures the removal of impurities. At the same time, the steaming tank is equipped with a stirrer for stirring the polypropylene powder so that it can evenly contact the steam.

Further, the product outlet is connected with the polypropylene powder outlet. The polypropylene product at the bottom of the flash tank merges with the polypropylene powder filtered at the bottom of the bag filter and then enters the steaming tank.

Further, a second gas phase outlet is provided on the top of the bag filter, and the second gas phase outlet communicates with the bottom of the low pressure propylene scrubber for recovering gas phase propylene. Preferably, the low-pressure propylene scrubber is a plate scrubber, and the number of sieve trays is 9 layers.

Further, the top of the steaming tank is also provided with a steam outlet, and the gas from the steam outlet enters the polypropylene scrubber to recover a small amount of polypropylene powder entrained in the steam. Preferably, the polypropylene scrubber is a plate scrubber, and the number of sieve trays is 16 layers.

Further, the top of the low-pressure propylene scrubber is provided with a gas-phase propylene outlet, and the gas-phase propylene outlet is connected with a mist separator for removing impurities in the recovered gas-phase propylene.

Further, the bottom of the mist separator is connected to the bottom of the low-pressure propylene scrubber, and is used to return the heavy components separated from the mist separator to the low-pressure propylene scrubber for washing. The propylene gas at the top contains oil droplets and some condensable substances. The mist separator can remove these impurities in time, thereby improving the purity of the recovered gas phase propylene.

Further, it also includes a polypropylene collection tank, which is connected to the polypropylene scrubber and the steaming tank at the same time.

Further, the side wall of the pre-polymerization reactor is provided with a mixed solvent inlet, and the mixed solvent inlet is connected with a pre-mixing tank, and the pre-mixing tank is used for pre-mixing materials, catalysts and solvents. Through premixing, the reaction materials, catalyst and solvent can be mixed uniformly, and the reaction center of the catalyst can be activated. An automatic stirring mechanism is arranged inside the pre-mixing tank, and the mixture is mixed more uniformly through further stirring.

Further, the top outlet of the pre-washing tower is sequentially connected with a first condenser and a first condensate storage tank, and the first condensate storage tank is connected with the pre-mixing tank for reuse of propylene. The gas phase propylene from the top of the scrubber is cooled by the condenser and then enters the condensate storage tank. There is a production line on the bottom side of the condenser storage tank, because the gas phase propylene contains a certain amount of propane, and propane does not participate in the reaction. Inert components, after repeated recovery and accumulation, the amount of propane will become larger and larger, so it must be continuously eliminated, and the remaining propylene will be cooled and returned to the pre-mixing tank for reuse, saving resources.

Preferably, the product outlet is provided with a sampling tank to detect whether the polypropylene discharged from the bottom of the flash tank is qualified.

Further, a second condenser and a second condensate storage tank are provided on the pipeline connecting the gas phase propylene outlet to the mist separator.

Further, a power separator is provided on the top of the flash tank to separate the polypropylene powder from the gas phase material as much as possible. Since the gas from the top of the flash tank needs to be recycled, it is necessary to carry as little or no powder as possible. Therefore, a power separator is installed at the top outlet of the flash tank to keep most of the powder in the flash tank and improve the flash evaporation. The separation efficiency of the tank.

Further, a pressure reducing valve is provided on the pipeline connecting the flash tank at the outlet of the polymerization reaction product. The pressure reducing valve is preferably a membrane type pressure reducing valve. Compared with other pressure reducing valves, the diaphragm pair of the membrane type pressure reducing valve is Pressure changes are more sensitive, and the accuracy is higher up to ±1%.

In addition, the present invention also provides a method for preparing polypropylene by adopting the above-mentioned intensified reaction system slurry method, which includes the following steps:

After the propylene is dispersed and broken into microbubbles, prepolymerization is carried out under the action of a catalyst to obtain a prepolymer;

The pre-polymerization is polymerized with propylene and hydrogen, which are dispersed and broken into microbubbles, to obtain a product;

The product is flashed, washed to remove impurities, filtered, and steamed.

Further, the materials, catalyst and solvent are pre-mixed in the pre-mixing tank and then passed into the pre-polymerization reactor. At the same time, the propylene gas is passed into the pre-polymerization micro-interface generator to be dispersed and broken into micro-bubbles. Propylene and pre-mixture are fully emulsified and then pre-polymerized to obtain pre-polymer; the pre-polymer is passed into the first micro-interface generator, and is fully emulsified with the propylene and hydrogen passed in at the same time, and then enters the polymerization reactor to polymerize After the reaction, the polymerized product then enters the flash tank for flash evaporation, the gas phase material on the top of the flash tank enters the pre-washing tower for washing and removing impurities, and the gas-phase propylene from the top of the pre-washing tower is condensed and then returned to the pre-mixing tank to repeat Utilizing, the material from the bottom of the pre-washing tower enters the bag separator to separate polypropylene powder; the polypropylene product discharged from the bottom of the flash tank merges with the polypropylene powder and then enters the steaming tank. Among them, the bag separator The propylene gas from the top enters the low-pressure propylene scrubber for washing, and then returns to the pre-polymerization micro-interface generator for recycling; the steam from the top of the steaming tank enters the polypropylene scrubber for scrubbing to recover a small amount of polypropylene entrained in the steam The powder, this part of the recycled polypropylene powder and the polypropylene coming out of the bottom of the steaming tank are combined and collected and then enter the polypropylene collection tank.

Further, the temperature of the polymerization reaction is 66-70°C, and the pressure is 1.6-2.0 MPa.

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

The intensified reaction system for preparing polypropylene by the slurry method of the present invention, by arranging a micro-interface generator on the pre-polymerization reactor and at the same time setting a micro-interface generating unit on the polymerization reactor, on the one hand, the material can be dispersed and broken into micro-bubbles , Thereby increasing the area of the phase boundary between the gas phase and the liquid phase, so that the mass transfer space is fully satisfied, and the residence time of the gas in the liquid phase is increased, thereby reducing gas consumption and energy consumption; on the other hand, at the same time The operating temperature and pressure inside the polymerization reactor are reduced, and the safety and stability of the entire reaction system are improved.

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 enhanced reaction system for preparing polypropylene of the present invention provided by an embodiment of the present invention.

Description of the drawings:

10-Pre-polymerization reactor; 101-Pre-polymerization micro-interface generator;

1010-Prepolymer export; 1020-Mixed solvent import;

20-Polymerization reactor; 201-First micro-interface generator;

202-Second micro-interface generator; 2010-Inlet;

2020-Polymerization reaction product export; 30-Pre-mixing tank;

40-flash tank; 401-pressure reducing valve;

402-heater; 403-power separator;

404-Sampling tank; 4010-First gas phase exit;

4020-product export; 50-pre-washing tower;

501-first condenser; 502-first condensate storage tank;

5010-solid phase exit; 60-bag filter;

6010-Polypropylene powder export; 6020-Second gas phase export;

70-steam tank; 7010-steam outlet;

80-low pressure propylene scrubber; 801-second condenser;

802-Second condensate storage tank; 803-Mist separator;

8010-gas phase propylene export; 90-polypropylene scrubber;

100-polypropylene collection tank.

detailed description

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 specific conditions are not 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 the terms "installed", "connected", and "connected" should be understood in a broad sense unless otherwise clearly specified and limited. For example, they can be fixed or detachable. 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 meaning 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 enhanced reaction system for preparing polypropylene of the present invention, which includes a pre-polymerization reactor 10 and a polymerization reactor 20. A pre-polymerized micro-interface generator 101, where a propylene delivery pipeline passes through the wall of the pre-polymerization reactor 10 to connect to the pre-polymerized micro-interface generator 101, so as to pass propylene into the pre-polymerized micro-interface generator; The polymerization reactor 20 is provided with a micro-interface generating unit for dispersing crushed materials into micro-bubbles.

It should be emphasized that the micro-interface generator unit includes a first micro-interface generator 201 and a second micro-interface generator 202. The first micro-interface generator 201 is arranged outside the polymerization reactor 20. The second micro-interface generator 202 is arranged inside the polymerization reactor 20, and the first micro-interface generator 201 is passed into the prepolymer obtained by the reaction of the polymerization reactor 20.

Specifically, the bottom of the pre-polymerization reactor 10 is provided with a pre-polymer outlet 1010, the side wall of the polymerization reactor 20 is provided with a feed port 2010, and one end of the first micro-interface generator 201 is The feed inlet 2010 is connected, and the other end is connected to the prepolymer outlet 1010. The second micro-interface generator 202 is connected with a gas-phase pipeline for recovering gas above the liquid level of the polymerization reactor 20 and a liquid-phase circulation pipeline for improving the power of the second micro-interface generator 202. The liquid-phase circulation is One end of the pipe is connected to the side wall of the polymerization reactor 20, and the other end is connected to the second micro-interface generator 202.

In this embodiment, the side wall of the pre-polymerization reactor 10 is provided with a mixed solvent inlet 1020, and the mixed solvent inlet 1020 is connected to a pre-mixing tank 30, which is used for mixing materials, catalysts and solvents. Premix. Through premixing, the reaction materials, catalyst and solvent can be mixed uniformly, and the reaction center of the catalyst can be activated. An automatic stirring mechanism is arranged inside the pre-mixing tank 30, and the mixture is mixed more uniformly through further stirring.

Further, a polymerization reaction product outlet 2020 is provided at the bottom of the polymer reactor 20, and the polymerization reaction product outlet 2020 is connected to the flash tank 40 for flashing the product after the polymerization reaction; the polymerization reaction product outlet 2020 is connected to The pipeline between the flash tanks is provided with a pressure reducing valve 401 and a heater 402 in sequence, and heating is performed before flashing, which can improve the efficiency of flashing. The pressure reducing valve 401 is preferably a membrane type pressure reducing valve. Compared with other pressure reducing valves, the diaphragm of the membrane pressure reducing valve is more sensitive to pressure, with a higher accuracy of ±1%.

Specifically, the top of the flash tank 40 is provided with a power separator 403 for separating the polypropylene powder from the gas phase material as much as possible. Since the gas processed from the top of the flash tank 40 needs to be recycled, it is necessary to carry as little or no powder as possible. Therefore, a power separator 403 is installed at the top outlet of the flash tank 40 to keep most of the powder in the flash tank 40. , Improve the separation efficiency of the flash tank 40.

Further, the bottom of the flash tank 40 is also provided with a product outlet 4020 for discharging polypropylene products, and the top of the flash tank 40 is provided with a first gas phase outlet 4010, and the material from the first gas phase outlet 4010 is passed into the pre-washing The tower 50 performs washing and impurity removal. Specifically, a first condenser 501 and a first condensate storage tank 502 are sequentially connected to the top of the pre-scrubbing tower 50, and the first condensate storage tank 502 is connected to the pre-mixing tank 30 for repeated propylene. use. The gas-phase propylene from the top of the pre-scrubbing tower 50 is cooled by the condenser 501 and then enters the first condensate storage tank 502. The bottom side of the first condenser storage tank 502 is provided with a production line because the gas-phase propylene contains a certain amount of Propane is an inert component that does not participate in the reaction. After repeated recovery and accumulation, the amount of propane will become larger and larger, so it must be continuously eliminated. The remaining propylene will be cooled and returned to the pre-mixing tank 30 for reuse. Save resources. A solid phase outlet 5010 is provided at the bottom of the pre-washing tower 50, and the solid phase outlet 5010 is connected to a bag filter 60 for separating polypropylene powder.

Specifically, a second gas phase outlet 6020 is provided at the top of the bag filter 60, and the second gas phase outlet 6020 communicates with the bottom of the low pressure propylene scrubber 80 for recovering gas phase propylene. The top of the low-pressure propylene scrubber 80 is provided with a gas-phase propylene outlet 8010, and the gas-phase propylene outlet 8010 is sequentially connected with a second condenser 801, a second condensate storage tank 801, and a mist separator 803. The mist is separated The device 803 is used to remove impurities in the recovered gas phase propylene. The bottom of the mist separator 803 is connected to the bottom of the low pressure propylene scrubber 80 to return the heavy components separated in the mist separator 803 to the low pressure propylene. Washing in the washing tower 80.

In this embodiment, the bottom of the flash tank 40 is also provided with a product outlet 4020 for discharging polypropylene products, and the product outlet 4020 is connected with a steaming tank 70 for removing hydrocarbons in the product. The pipe connecting the product outlet 4020 to the steaming tank 70 is provided with a sampling tank 404 for detecting whether the polypropylene discharged from the bottom of the flashing tank 40 is qualified. The bottom of the bag filter 60 is provided with a polypropylene powder outlet 6010, the polypropylene powder outlet 6010 is connected to the steaming tank 70 for removing hydrocarbons in the polypropylene powder, the product outlet 4020 It merges and communicates with the polypropylene powder outlet 6010. In this embodiment, a steam jacket is provided on the outside of the steaming tank 70 to keep the temperature at about 105° C. This not only ensures that the steam in the steaming tank 70 does not condense, but also ensures the removal of impurities. At the same time, a stirrer is provided in the steaming tank 70 for stirring the polypropylene powder so that it can evenly contact the steam. The top of the steaming tank 70 is also provided with a steam outlet 7010, and the gas from the steam outlet 7010 enters the polypropylene scrubber 90 to recover a small amount of polypropylene powder entrained in the steam.

In this embodiment, a polypropylene collection tank 100 is further included, and the polypropylene collection tank 100 is connected to the polypropylene scrubber 90 and the steaming tank 70 at the same time.

The working process and principle of the enhanced reaction system for preparing polypropylene by the slurry method of the present invention will be briefly described below.

First, the materials, catalyst and solvent are pre-mixed in the pre-mixing tank 30 and then passed into the pre-polymerization reactor 10. At the same time, the propylene gas is passed into the pre-polymerization micro-interface generator 101 to be dispersed and broken into micro-bubbles. Propylene and the premix are fully emulsified and then pre-polymerized to obtain the prepolymer; the prepolymer is passed into the first micro-interface generator 201, and the propylene and hydrogen passed through at the same time are fully emulsified before entering the polymerization reactor 20. The polymerization reaction occurs, and the temperature of the polymerization reaction is 66-70°C and the pressure is 1.6-2.0 MPa. The polymerized product then enters the flash tank 40 for flash evaporation. The gas phase at the top of the flash tank 40 enters the scrubbing tower 50 for washing and removing impurities. The gas phase propylene from the top of the scrubbing tower 50 is condensed and then returned to the pre-mixing tank to repeat Utilizing, the material at the bottom of the pre-washing tower 50 enters the bag filter 60 to separate polypropylene powder; the polypropylene product discharged from the bottom of the flash tank 40 merges with the polypropylene powder and then enters the steaming tank 70, where the bag The propylene gas from the top of the type separator 60 enters the low-pressure propylene scrubber 80 for washing, and then returns to the pre-polymerization micro-interface generator 101 for recycling; the steam from the top of the steaming tank 70 enters the polypropylene scrubber 90 for washing In order to recover a small amount of polypropylene powder entrained in the steam, this part of the recycled polypropylene powder and the polypropylene coming out of the bottom of the steaming tank 70 are combined and collected and then enter the polypropylene collection tank 100.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, 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: The technical solutions recorded in the foregoing embodiments can still be modified, or some or all of the technical features can be equivalently replaced; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the technical solutions of the embodiments of the present invention. Scope.

Claims

A reinforced reaction system for preparing polypropylene by a slurry method is characterized in that it comprises: a pre-polymerization reactor and a polymerization reactor which are sequentially connected, and the pre-polymerization reactor is provided with a pre-polymerization reactor for dispersing crushed materials into microbubbles. Interface generator, said polymerization reactor is provided with a micro-interface generating unit for dispersing crushed materials into micro-bubbles;

A polymerization reaction product outlet is provided at the bottom of the polymer reactor, and the polymerization reaction product outlet is connected to a flash tank for flashing the product after the polymerization reaction; the top of the flash tank is provided with a first gas phase outlet , The material from the first gas phase outlet is passed into the pre-washing tower for washing and removing impurities; the bottom of the pre-washing tower is provided with a solid phase outlet, and the material from the solid phase outlet is passed into the bag filter to separate polypropylene Powder; the bottom of the flash tank is provided with a product outlet for the discharge of polypropylene products, and the product outlet is connected with a steaming tank for the removal of hydrocarbons in the product.
The intensified reaction system for preparing polypropylene by the slurry method according to claim 1, wherein the bottom of the bag filter is provided with a polypropylene powder outlet, and the polypropylene powder outlet is connected to the steaming tank for use For the removal of hydrocarbons in polypropylene powder.
The intensified reaction system for preparing polypropylene by the slurry method according to claim 2, wherein the product outlet is connected with the polypropylene powder outlet.
The intensified reaction system for preparing polypropylene by the slurry method according to claim 1, wherein a second gas phase outlet is provided on the top of the bag filter, and the second gas phase outlet is in communication with the bottom of the low pressure propylene scrubber For the recovery of gas phase propylene.
The intensified reaction system for preparing polypropylene by the slurry method according to claim 1, wherein the top of the steaming tank is also provided with a steam outlet, and the gas from the steam outlet enters the polypropylene scrubbing tower for recovery A small amount of polypropylene powder entrained in the steam.
The intensified reaction system for preparing polypropylene by the slurry method according to claim 4, wherein the top of the low-pressure propylene scrubber is provided with a gas-phase propylene outlet, and the gas-phase propylene outlet is connected with a mist separator for removing Impurities in recovered gas phase propylene.
The intensified reaction system for preparing polypropylene by the slurry method according to claim 6, wherein the bottom of the mist separator is connected to the bottom of the low-pressure propylene scrubber for separating the mist separator from The heavy components are returned to the low-pressure propylene scrubber for washing.
The intensified reaction system for preparing polypropylene by the slurry method according to claim 5, characterized in that it further comprises a polypropylene collecting tank, and the polypropylene collecting tank is connected to the polypropylene washing tower and the steaming tank at the same time.
The method for preparing polypropylene by adopting the intensified reaction system of any one of claims 1-8, which is characterized in that it comprises the following steps:

After the propylene is dispersed and broken into microbubbles, prepolymerization is carried out under the action of a catalyst to obtain a prepolymer;

The pre-polymerization is polymerized with propylene and hydrogen, which are dispersed and broken into microbubbles, to obtain a product;

The product is flashed, washed to remove impurities, filtered, and steamed.
The method according to claim 9, wherein the temperature of the polymerization reaction is 66-70°C and the pressure is 1.6-2.0 MPa.