WO2023138075A1

WO2023138075A1 - Device and method for polycondensation of polyols by means of cyclic compounds

Info

Publication number: WO2023138075A1
Application number: PCT/CN2022/118441
Authority: WO
Inventors: 张志炳; 孙海宁; 周政; 张锋; 李磊; 孟为民; 杨高东; 杨国强; 刘甲
Original assignee: 南京延长反应技术研究院有限公司
Priority date: 2022-01-19
Filing date: 2022-09-13
Publication date: 2023-07-27
Also published as: CN114471403A

Abstract

Provided in the present invention is a device for polycondensation of polyols by means of cyclic compounds. The device comprises a reaction kettle, a first micro-interface generator is arranged at the bottom layer in the reaction kettle, and a second micro-interface generator is arranged in the middle layer in the reaction kettle. A first one-way channel used for preventing material backflow is arranged between the first micro-interface generator and the second micro-interface generator, and a second one-way channel is arranged above the second micro-interface generator. A polyol pipeline and a cyclic compound pipeline are arranged on the side edge of the bottom of the reaction kettle. The first micro-interface generator is connected to the cyclic compound pipeline, so as to introduce vaporized cyclic compounds and perform dispersion and crushing, and a polycondensation product pipeline is arranged at the top of the reaction kettle. By using micro-interface enhanced reaction technology, the consumption rate of the cyclic compound gas can be greatly increased, the partial pressure of the cyclic compound in the gas phase is effectively reduced, and the intrinsic safety of the apparatus is greatly improved.

Description

A device and method for polycondensation of polyols using cyclic compounds

technical field

The invention belongs to the technical field of high molecular polymers, and in particular relates to a device and method for polycondensation of polyols by using cyclic compounds.

Background technique

Condensation polymerization reaction, referred to as polycondensation reaction, refers to the reaction in which one or more monomers condense with each other to form a polymer, and its main product is called a polycondensate. The monomer of the condensation polymerization reaction is a compound with two (or more) reactive functional groups. When polymerizing, it removes small molecules to form a polymer, so the molecular weight of the repeating structural unit of the polymer is smaller than that of the monomer.

Most of the existing polycondensation reactions use a stirred tank reactor, which has the advantages of compact structure, simple equipment, high process operation flexibility, large stirring power, and suitable for the production of high molecular weight polyether. But this kind of reactor also has obvious disadvantages. The effect of stirring and breaking bubbles during the reaction is not good, and the uneven gas-liquid mixing inside the reactor can easily produce concentration and temperature gradients, resulting in low mass transfer and reaction rate; the existence of coiled tube heat exchangers reduces the effective volume of the kettle, reduces the production capacity of the reactor, and makes maintenance and replacement difficult; In addition, if the mechanical seal is damaged or fails, oxides may overflow from the reactor, and external substances may also enter the reactor, causing reactor safety issues.

In view of this, the present invention is proposed.

Contents of the invention

The first object of the present invention is to provide a device for polycondensation of polyols using cyclic compounds, which solves the problems of small gas-liquid contact surface, poor gas dispersion performance, low mass transfer efficiency, and wide molecular weight distribution of products in stirred tank reactors. The present invention uses micro-interface enhanced reaction technology to form a micro-interface system in the reactor, increasing the gas-liquid contact area by dozens of times, greatly enhancing gas-liquid mass transfer efficiency, and hoping to obtain products with narrow molecular weight distribution. The partial pressure of the cyclic compound in the gas phase greatly improves the intrinsic safety of the equipment.

The second object of the present invention is to provide a polycondensation device using cyclic compounds for polyhydric alcohols, which is safe in operation and high in polycondensation reaction efficiency.

In order to achieve the above technical purpose, the present invention provides the following technical solutions:

The invention provides a device for polycondensation of polyols using cyclic compounds, comprising a reactor, the inner bottom layer of the reactor is provided with a first micro-interface generator, the inner middle layer of the reactor is provided with a second micro-interface generator, a first one-way channel is provided between the first micro-interface generator and the second micro-interface generator to prevent material backflow, a second one-way channel is provided above the second micro-interface generator, polyol pipes and cyclic compound pipes are provided on the bottom side of the reactor, and the first micro-interface generator is connected to the annular The compound pipeline is used to introduce the vaporized cyclic compound for dispersion and crushing, and the top of the reaction kettle is provided with a polycondensation product pipeline.

Most of the stirred tank reactors used in the prior art have the advantages of compact structure, simple equipment, high process operation flexibility, high stirring power, and are suitable for the production of high molecular weight polyethers. Gas-phase cyclic compounds create localized hot spots, creating a risk of explosion (electric dipole formation between the stirrer and the reactor wall, and overheating of the mechanical seal). In addition, if the mechanical seal is damaged or fails, oxides may overflow from the stirred tank reactor, and external substances may also enter the stirred tank reactor, causing reactor safety issues.

In the present invention, the first micro-interface generator is arranged at the bottom of the reaction kettle to break and disperse the cyclic compound into microbubbles of the cyclic compound, which increases the mass transfer area of the phase boundary between the cyclic compound and the polyol, greatly enhances the gas-liquid mass transfer efficiency, and improves the efficiency of the polycondensation reaction. The reason why the first micro-interface generator is arranged at the bottom of the reactor, and preferably placed on the center line of the reactor. First of all, the microbubbles run upwards, and placing the first microinterface generator at the bottom can allow the microbubbles to react with the polyol for a longer time, which will also improve the efficiency of the polycondensation reaction. Secondly, it is on the center line of the reactor because it can make the bubbles more evenly distributed inside the reactor. If the first micro-interface generator is placed on one side of the reactor, there must be fewer microbubbles in places far away from the first micro-interface generator, and the reaction efficiency will definitely not be high.

The first one-way channel is also set above the first micro-interface generator, which makes the material can only go from bottom to top, and the material on the top cannot flow back. After the polycondensation reaction below is completed, it enters the middle of the reactor through the first one-way channel and continues to react in the second micro-interface generator. In this way, the product from the middle of the reactor must be more pure than the product from the bottom. In order to prevent high-purity products and low-purity products from being mixed together, the first one-way channel is set up to block the bottom and middle of the reactor.

A second one-way channel is also arranged above the second micro-interface generator. The effect of the second one-way channel is the same as that of the first one-way channel. The product coming out of the first one-way channel can be discharged and collected through the polycondensation product pipeline, which can further ensure the purity of the polycondensation product.

Preferably, the second micro-interface generator is connected with a second external circulation channel, the outlet of the second external circulation channel is arranged in the middle of the first one-way channel and the second micro-interface generator, the outlet of the second external circulation channel is sequentially connected with a second one-way valve, a second circulation pump and a second heat exchanger, and the return port of the second external circulation is connected to the top of the second micro-interface generator. The side of the second micro-interface generator and the outside of the reaction kettle are provided with a second external circulation channel. The outlet of this second external circulation channel is set above the first one-way channel and close to the first one-way channel. In this way, the unreacted liquid phase and gas phase materials coming out of the first one-way channel are directly sucked into the second external circulation channel. After heating and heating, they are sent to the second micro-interface generator for crushing and dispersing again. This process improves the mass transfer efficiency between gas and liquid again, and improves the efficiency of polycondensation reaction.

Preferably, the first micro-interface generator is communicated with a first external circulation channel, the outlet of the first external circulation channel is arranged at the bottom of the reactor, the outlet of the first external circulation channel is connected with a first one-way valve, a first circulation pump and a first heat exchanger in sequence, and the return port of the first external circulation is communicated with the top of the first micro-interface generator. The side of the first micro-interface generator and the outside of the reactor are connected with a first external circulation channel. The reason why the outlet of the first external circulation channel is arranged at the bottom of the reactor is that the materials at the bottom of the reactor can be rolled back to the first micro-interface generator, so that the reaction materials can be effectively utilized. The first external circulation channel is provided with a first one-way valve to prevent the material from flowing backward from the first external circulation channel, and then the circulation pump provides power, and then heats through the heat exchanger, and the material is heated to the reaction temperature and then returned to the first micro-interface generator.

Preferably, a sieve plate is provided on the top of the reactor to slow down the flow rate of the material.

Preferably, a nitrogen inlet pipe is connected to the top of the reactor. The reason why the nitrogen inlet pipe is arranged on the top of the reactor is that nitrogen is used as a purge gas to sweep the top of the reactor, and the second is that the pressure inside the reactor can be controlled.

Preferably, a tail gas pipeline is opened on the top of the reactor, and the tail gas pipeline is divided into two pipelines, one of which is connected to a second external circulation channel, and the other pipeline is used for transporting through a cold well for collecting cyclic compounds before being discharged. The purpose of setting up the cold well here is to collect and store the cyclic compounds after liquefaction, so as to prevent the cyclic compounds from polluting the air.

Preferably, the product pipeline is divided into two pipelines, one pipeline returns the product to the second external circulation channel, and the other pipeline discharges and collects the product.

Preferably, the second external circulation channel is provided with a second product outlet for discharging the product. The polycondensation product output from the second product outlet is a little higher in purity than the polycondensation product output from the first product outlet, and these can be discharged and collected.

Preferably, the first external circulation channel is provided with a first product outlet for discharging products. Polycondensation products with low purity can also be obtained after being treated by the first micro-interface generator, and these polycondensation products are discharged and collected through the first product outlet.

In addition, the present invention also provides a method for polycondensation device utilizing cyclic compounds, comprising the steps of:

Micro-interface dispersion and crushing of gaseous cyclic compounds, polycondensation of micro-bubbles of cyclic compounds and polyols to form high polymers of polyols;

The micro-interface disperses and breaks the unreacted gaseous cyclic compound again, and the micro-bubbles of the cyclic compound polycondensate with the polyol to form a high polymer of polyol;

The product was drained and collected.

The method of the invention can greatly accelerate the consumption rate of the cyclic compound through the micro-interface strengthening reaction technology, effectively reduce the partial pressure of the cyclic compound in the gas phase, and greatly improve the intrinsic safety of the equipment.

Compared with the prior art, the present invention has the advantages of:

(1) The gas-liquid two-phase mass transfer efficiency is greatly improved, and the molecular weight distribution of the product is improved.

The ethoxylation reactor is a typical vapor-liquid phase reactor. In the reactor, the vapor-phase cyclic compound enters the liquid phase by diffusion to react, which is controlled by chemical reaction and interface mass transfer. The mixing and mass transfer of gas-liquid materials are important factors affecting the reaction performance, production capacity and technological advancement of the reactor. Mass transfer efficiency is an important index to measure the technical level of ethoxylation equipment, and mass transfer enhancement is an important direction for the improvement of all ethoxylation processes. The gas-liquid contact surface of the stirred tank reactor is small, the dispersion performance of the gas is poor, the mass transfer efficiency is low, and the molecular weight distribution of the product is wide. The present invention forms a micro-interface system in the reactor by applying the micro-interface enhanced reaction technology, increases the gas-liquid contact area dozens of times, greatly enhances the gas-liquid mass transfer efficiency, and expects to obtain products with narrow molecular weight distribution.

(2) Improve the intrinsic safety performance of the equipment.

In the gas phase space above the tank reactor, cyclic compounds gather in the gas phase, and the dynamic seal of the stirring paddle is easy to leak, generate static electricity, and cause poisoning, explosion and other safety accidents. Through the application of micro-interface enhanced reaction technology, the consumption rate of cyclic compounds can be greatly accelerated, the partial pressure of cyclic compounds in the gas phase can be effectively reduced, and the intrinsic safety of equipment can be greatly improved.

Description of drawings

Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiment. The drawings are only for the purpose of illustrating a preferred embodiment and are not to be considered as limiting the invention. Also throughout the drawings, the same reference numerals are used to designate the same components. In the attached picture:

Figure 1 is a schematic structural diagram of a device for polycondensation of polyols using cyclic compounds provided in this embodiment.

in:

10- Reactor;

12-the second micro-interface generator; 111-the first one-way channel;

121-the second one-way channel; 13-polyol pipeline;

14-cyclic compound pipeline; 17-condensation product pipeline;

102-the second outer circulation channel; 128-the exit of the second outer circulation channel;

122-the second one-way valve; 123-the second circulation pump;

124-the second product outlet; 125-the second valve;

126-the second heat exchanger; 127-the return port of the second external circulation;

101-the first outer circulation channel; 118-the exit of the first outer circulation channel;

112-the first one-way valve; 113-the first circulation pump;

114-the first product outlet; 115-the first valve;

116-the first heat exchanger; 117-the return port of the first external circulation;

15-nitrogen intake pipe; 16-exhaust pipe;

161-reflux valve; 162-cold well;

171-the third valve; 18-sieve plate.

Detailed ways

The technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings and specific embodiments, but those skilled in the art will understand that the embodiments described below are some of the embodiments of the present invention, rather than all embodiments, and are only used to illustrate the present invention, and should not be considered as limiting the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention. Those who do not indicate the specific conditions in the examples are carried out according to the conventional conditions or the conditions suggested by the manufacturer. The reagents or instruments used were not indicated by the manufacturer, and they were all conventional products that could be purchased from the market.

In the description of the present invention, it should be noted that the orientations or positional relationships indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and thus cannot be construed as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and should not be construed as indicating or implying relative importance.

In the description of the present invention, it should be noted that, unless otherwise specified and limited, the terms "installation", "connection" and "connection" should be understood in a broad sense, for example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be a direct connection or an indirect connection through an intermediate medium, or it may be an internal connection between two components. Those of ordinary skill in the art can understand the specific meanings of the above terms in the present invention in specific situations.

In order to illustrate the technical solution in the present invention more clearly, the following will be described in the form of specific examples.

Example

Referring to FIG. 1 , it is a schematic structural diagram of a device for polycondensation of polyols using cyclic compounds provided by the present invention. The device includes a reactor 10, the reactor 10 is divided into bottom, middle and top three parts, the bottom and the middle are separated by the first one-way channel 111, and the middle and the top are separated by the second one-way channel 121. In this embodiment, the cyclic compound is selected as propylene oxide, and the polyol is ethylene glycol.

First, a first micro-interface generator 11 is provided at the bottom of the reaction kettle 10 . The first micro-interface generator 11 is arranged on the center line of the reaction kettle 10 . The polyol pipeline 13 enters the reactor 10 through the side wall at the bottom of the reactor 10, and ethylene glycol is passed into the reactor 10. The cyclic compound pipeline 14 also enters the reactor 10 through the side wall at the bottom of the reactor 10 and communicates with the top of the first micro-interface generator 11. Propylene oxide is vaporized instantly when it enters the reactor 10, because the operating temperature of the reactor 10 will vaporize the propylene oxide. A first external circulation channel 101 is also provided around the first micro-interface generator 11 , and an outlet 118 of the first external circulation channel is opened at the bottom of the reactor 10 . The outlet 118 of the first external circulation channel passes the material at the bottom of the reactor 10 through the first one-way valve 112 and is sucked and circulated by the first circulation pump 113, and then returns to the first micro-interface generator 11 after passing through the first heat exchanger 116, that is, the first external circulation channel 101 returns the material to the first micro-interface generator 11 through the return port 117 of the first external circulation. There is also a passage separated from the first external circulation passage 101, this passage is arranged in the middle of the first circulation pump 113 and the first heat exchanger 116, and a first valve 115 is also provided on this passage, followed by the first product outlet 114 behind the first valve 115, the first product outlet 114 can collect some polyethylene glycols with not too high purity.

Secondly, the middle section of the reaction kettle 10 is provided with a second micro-interface generator 12 . The second micro-interface generator 12 is also arranged on the center line of the reaction kettle 10 , directly above the first micro-interface generator 11 . The middle section of the reaction kettle 10 is provided with an outlet 128 of the second external circulation channel near the first one-way channel 111, and the materials coming out of the outlet 128 of the second external circulation channel pass through the second one-way valve 122, the second circulation pump 123 and the second heat exchanger 126 in sequence, and then return to the second micro interface generator 12 from the return port 127 of the second external circulation. In this way, the unreacted cyclic compound microbubbles coming out from the bottom of the reactor 10 are entrained into the second micro-interface generator 12 for secondary crushing and dispersion. A channel is also branched from the second external circulation channel 102, and the channel is provided with a second valve 125 and a second product outlet 124 for collecting relatively high-purity polyethylene glycol.

Finally, the top of the reaction kettle 10 is provided with sieve plates 18, and these sieve plates 18 slow down the rising speed of the air bubbles. On the liquid level at the top of the reactor 10, a nitrogen gas inlet pipe 15 is also provided to purge the unreacted propylene oxide gas at the top of the reactor 10. A part of these propylene oxide gases is recovered after being cooled through the cold well 162, and then the remaining tail gas is discharged through the tail gas pipeline 16; A polycondensation product pipeline 17 is opened above the sieve plate 18 at the top of the reactor 10, and a part of the polyethylene glycol is collected and stored, and the other part is also returned to the second external circulation channel 102 for reuse.

Apply the above-mentioned device to produce polyethylene glycol, start the reaction by adding 150L of ethylene glycol into the reactor 10, and replace the reactor 10 with nitrogen, and feed nitrogen until the pressure is 140KPa. Start the first micro-interface generator and the second micro-interface generator and raise the temperature of the reactor 10 to 100° C. to form a liquid homogeneous solution. Continuously add liquid propylene oxide into the first micro-interface generator 11 at a feed rate of 100-160 kg/h. The liquid propylene oxide is vaporized as soon as it enters the reactor 10 and becomes gaseous propylene oxide, which is passed into the first micro-interface generator 11. During the reaction, the first heat exchanger and the second heat exchanger are used to control the reaction temperature at about 130-140°C.

comparative example

A stirred tank reactor was used for the comparative example. Firstly, 150L of initiator was added to the tank at the beginning of the reaction, and the reactor was replaced with nitrogen, and nitrogen gas was introduced until the pressure was 150kPa; stirring was started to raise the temperature of the materials in the reactor to 100°C to form a liquid homogeneous solution; liquid ethylene oxide was continuously added to the feed port at the bottom of the reactor, and the feeding rate was 100-150kg/h; The temperature is 130-150°C, and the reaction pressure is up to 550kPa; after the feeding is completed, continue to heat-preserve and mature, the feeding time is 3 hours, and the curing time is 0.5-1h; when the pressure difference between the feed pipeline and the inside of the kettle is less than 150kPa, the pressure inside the kettle exceeds 550kPa, and the temperature inside the kettle exceeds 190°C, the interlock starts to automatically cut off the EO feed.

Produce polyethylene glycol according to above-mentioned embodiment, obtain following data:

反应罐内参数Parameters in the reaction tank	实施例Example	对比例comparative example
初期反应压力(KPa)Initial reaction pressure (KPa)	140140	150150
末期反应压力(KPa)Final reaction pressure (KPa)	530530	550550
反应温度(℃)Reaction temperature (°C)	130130	150150
末期反应粘稠度(cp)Final reaction viscosity (cp)	8585	9595
环氧丙烷加入速率(kg/h)Propylene oxide addition rate (kg/h)	150150	120120

It can be seen from the above experimental data that although the stirred tank reactor used in the comparative example has the advantages of compact structure, simple equipment, large process operation flexibility, large stirring power, and is suitable for the production of high molecular weight polyether. But this kind of reactor also has obvious disadvantages. The effect of stirring and breaking the bubbles during the reaction is not good, and the uneven gas-liquid mixing in the reactor can easily produce concentration and temperature gradients, resulting in low mass transfer and reaction rate; the existence of the snake tube reduces the effective volume of the reactor, which reduces the production capacity of the reactor, and it is difficult to repair and replace; the existence of the agitator is easy to cause local hot spots in the gas phase ethylene oxide, resulting in the risk of explosion. In addition, if the mechanical seal is damaged or fails, oxides may overflow from the reactor, and external substances may also enter the reactor, causing reactor safety issues. In the embodiment of the present invention, a micro-interface system is formed in the reactor, which increases the gas-liquid contact area by dozens of times, greatly enhances the gas-liquid mass transfer efficiency, and effectively reduces the reaction pressure and reaction temperature. Also, by applying the micro-interface enhanced reaction technology, the consumption rate of ethylene oxide is greatly accelerated, the partial pressure of ethylene oxide in the gas phase is effectively reduced, and the intrinsic safety of the equipment is greatly improved.

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 can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.

Claims

A device for polycondensation of polyols using cyclic compounds, characterized in that it includes a reactor, the inner bottom of the reactor is provided with a first micro-interface generator, the inner middle layer of the reactor is provided with a second micro-interface generator, a first one-way channel is provided between the first micro-interface generator and the second micro-interface generator to prevent material from flowing backward, a second one-way channel is provided above the second micro-interface generator, a polyol pipeline and a cyclic compound pipeline are provided on the bottom side of the reactor, and the first micro-interface generator is connected to the ring A cyclic compound pipeline is used to introduce the vaporized cyclic compound for dispersion and crushing, and a polycondensation product pipeline is arranged on the top of the reactor.
The device for polycondensation of polyols using cyclic compounds according to claim 1, wherein the second micro-interface generator is connected to a second external circulation channel, the outlet of the second external circulation channel is arranged in the middle of the first one-way channel and the second micro-interface generator, the outlet of the second external circulation channel is connected to a second one-way valve, a second circulation pump and a second heat exchanger in sequence, and the return port of the second external circulation is connected to the top of the second micro-interface generator.
The device for polycondensation of polyols using cyclic compounds according to claim 1, wherein the first micro-interface generator is connected to a first external circulation channel, the outlet of the first external circulation channel is arranged at the bottom of the reactor, the outlet of the first external circulation channel is connected to a first one-way valve, a first circulation pump and a first heat exchanger in sequence, and the return port of the first external circulation is connected to the top of the first micro-interface generator.
The device for polycondensation of polyols using cyclic compounds according to claim 1, wherein a sieve plate is arranged on the top of the reactor to slow down the flow rate of materials.
The device for polycondensation of polyols using cyclic compounds according to claim 1, characterized in that a nitrogen gas inlet pipe is connected to the top of the reactor.
The device for polycondensation of polyols using cyclic compounds according to claim 2, wherein a tail gas pipeline is provided at the top of the reactor, and the tail gas pipeline is divided into two pipelines, one of which is connected to the second external circulation channel, and the other pipeline is used for transporting through a cold well for collecting cyclic compounds and then discharged.
The device for polycondensation of polyols using cyclic compounds according to claim 2, wherein the product pipeline is divided into two pipelines, one pipeline returns the product to the second external circulation channel, and the other pipeline discharges and collects the product.
The device for polycondensation of polyols using cyclic compounds according to claim 2, wherein a second product outlet for discharging products is provided on the second external circulation channel.
The device for polycondensation of polyols using cyclic compounds according to claim 3, wherein a first product outlet for discharging products is provided on the first external circulation channel.
A method using any one of claims 1-9 to utilize cyclic compounds to polycondensation device, is characterized in that, comprises the steps:

Micro-interface dispersion and crushing of gaseous cyclic compounds, polycondensation of micro-bubbles of cyclic compounds and polyols to form high polymers of polyols;

The micro-interface disperses and breaks the unreacted gaseous cyclic compounds again, and the micro-bubbles of the cyclic compounds are polycondensed with polyols to form high polymers of polyols;

The product was drained and collected.