Transesterification reaction system for plastic alcoholysate

Abstract

The utility model relates to the field of chemical equipment, in particular to an ester exchange reaction system for plastic alcoholysate, which comprises a first ester exchange reaction kettle, a second ester exchange reaction kettle and a vacuum pump, the first ester exchange reaction kettle and the second ester exchange reaction kettle are connected with the same vacuum pump through a pipeline, and the first ester exchange reaction kettle is used for carrying out primary ester exchange reaction; the second ester exchange reaction kettle is used for carrying out secondary ester exchange reaction; the vacuum pump is used for pumping methanol in the first ester exchange reaction kettle and the second ester exchange reaction kettle. The conversion rate of the reaction can be improved by continuously carrying out transesterification twice; the two ester exchange reaction kettles are connected with the same vacuum pump, so that the reaction byproduct methanol can be continuously pumped out, the reaction conversion rate is further improved, and meanwhile, under the negative pressure condition, the heating temperature of the ester exchange reaction kettles can be reduced, and energy conservation is facilitated.

Description

TECHNICAL FIELD

[0001] The utility model relates to the field of chemical equipment especially relates to a plastic alcoholysis ester exchange reaction system. BACKGROUND

[0002] At present, the ester exchange reaction of plastic alcoholysis usually only uses one ester exchange reaction kettle, and due to the influence of ester exchange equilibrium conversion rate, it is difficult to achieve higher conversion rate, and at the same time, too high reaction temperature will cause the polycondensation reaction of the product.

[0003] CN118547390A discloses a method for recycling polyester fibers from PET waste, which specifically comprises the following steps: (1) PET waste pretreatment: removing non-PET materials from the PET waste, and then crushing, granulating and drying the PET waste; (2) regenerating DMT synthesis: feeding the PET waste treated in step (1) into an alcoholysis reaction kettle, adding ethylene glycol for alcoholysis reaction, filtering out solid impurities after reaction to obtain crude product BHET, mixing the crude product BHET with methanol and conveying it to an ester exchange reaction kettle to obtain crude product DMT; (3) DMT separation and purification: conveying the crude product DMT to a distillation tank, and conveying the distilled DMT to a rectification tower for purification to obtain high-purity DMT product; (4) regenerating PET and spinning: using the high-purity DMT product obtained in step (3) as raw material to produce regenerating PTE product in a polymerization device, and preparing regenerating polyester fibers through a spinning device. Although this scheme optimizes the pretreatment technology, regenerating DMT synthesis and refining technology, and high-purity DMT separation and purification key technology process, and realizes the preparation of high-purity regenerating DMT, but in the process of preparing BHET in step (2), only one ester exchange reaction kettle is used, and due to the influence of ester exchange equilibrium conversion rate, it is difficult to achieve higher conversion rate, therefore, this scheme cannot solve the problem of limited ester exchange reaction equilibrium conversion rate.

[0004] CN117820114A discloses a catalyst delivery process for recycling waste PET by chemical method, which comprises the following steps: (1) adding ethylene glycol in a depolymerization reaction kettle, adding PET after nitrogen replacement is completed, adding catalyst slurry after heating, and obtaining intermediate product BHET after filtering and refining the reaction product after depolymerization reaction is completed; (2) adding methanol in an ester exchange reaction kettle, then adding the intermediate product BHET, adding catalyst slurry after heating, and obtaining product DMT after crystallization and refining treatment of the reaction product after ester exchange reaction. Similarly, this scheme only uses one ester exchange reaction kettle, and cannot solve the problem of limited ester exchange reaction equilibrium conversion rate.

[0005] CN116623310A discloses a low ethylene glycol ratio polyester regeneration method, which utilizes ethylene glycol alcoholysis process to degrade waste polyester fibers and then aggregates to obtain high-purity terephthalate glycol BHET, and the specific steps are as follows: a, depolymerization of waste polyester fibers, addition of neutralizing catalyst to liquefy and dissolve the waste polyester fibers; b, decolorization and purification of the depolymerization product, the product obtained in step a is a liquefied solution containing impurities, which is decolorized by stirring and then purified by filtration; c, re-polymerization of the depolymerization product after complete purification and decolorization, after obtaining the depolymerization product after complete purification and decolorization in step b, a condensation catalyst and a heat stabilizer are added, and then under specific temperature and pressure, sufficient stirring and mixing are carried out to obtain regenerated polyester; d, drying treatment of the obtained regenerated polyester into powder or granular; e, processing of the powder or granular product into polyester fibers for regeneration use, and similarly, this scheme only uses one ester exchange reaction kettle, and cannot solve the problem of limited equilibrium conversion rate of ester exchange reaction.

[0006] Therefore, how to improve the equilibrium conversion rate of ester exchange reaction of plastic alcoholysis product is a technical problem to be solved. SUMMARY

[0007] To solve the above technical problems, the utility model provides a plastic alcoholysis product ester exchange reaction system, which can improve the equilibrium conversion rate of ester exchange reaction, and can also reduce the reaction temperature.

[0008] The utility model provides a plastic alcoholysis product ester exchange reaction system, the system includes first ester exchange reaction kettle, second ester exchange reaction kettle and vacuum pump, first ester exchange reaction kettle with second ester exchange reaction kettle is connected through pipeline series connection, first ester exchange reaction kettle with second ester exchange reaction kettle with same vacuum pump is connected through pipeline,

[0009] The first ester exchange reaction kettle is used for carrying out first ester exchange reaction.

[0010] The second ester exchange reaction kettle is used for carrying out second ester exchange reaction.

[0011] The vacuum pump is used for extracting methanol in the first ester exchange reaction kettle and the second ester exchange reaction kettle.

[0012] Further, the first ester exchange reaction kettle and the second ester exchange reaction kettle both include kettle body, stirrer, filler layer, jacket, coil pipe, temperature controller, feed inlet and discharge outlet.

[0013] Further, the kettle body is cylindrical, and the material is stainless steel or carbon steel.

[0014] Further, the stirrer is located on the top of the kettle body, and the stirrer is a paddle type.

[0015] Further, the packing layer is located on the upper part of the kettle body, and is used for increasing the contact area of the material.

[0016] Further, the jacket is located on the outside of the kettle body and wraps the kettle body, and the coil is located on the inside of the kettle body, and the jacket and the coil are used for heating the material in the kettle body.

[0017] Further, the temperature controller is located on the top of the kettle body and is used for controlling the heating temperature of the ester exchange reaction kettle.

[0018] Further, the heating temperature of the first ester exchange reaction kettle is 130-160 DEG C, and the equilibrium conversion rate of the ester exchange reaction is 88-90%.

[0019] Further, the heating temperature of the second ester exchange reaction kettle is 160-180 DEG C, and the equilibrium conversion rate of the ester exchange reaction is 97-99%.

[0020] Further, the top and the side wall of the kettle body are respectively provided with the feeding port, and the feeding port is respectively marked as the first feeding port and the second feeding port, the first feeding port is used for externally adding the material, and the second feeding port is used for transmitting the material between the ester exchange reaction kettles.

[0021] Further, the bottom of the kettle body is provided with the discharging port, and the discharging port of the first ester exchange reaction kettle is connected with the second feeding port of the second ester exchange reaction kettle.

[0022] Further, the top of the first ester exchange reaction kettle and the top of the second ester exchange reaction kettle are respectively connected with the same vacuum pump through the pipeline.

[0023] The beneficial effects of the utility model

[0024] 1. In the prior art, the ester exchange reaction of plastic alcoholysis product usually only uses one ester exchange reaction kettle, and due to the influence of the equilibrium conversion rate of ester exchange, the reaction is difficult to reach a higher conversion rate, and meanwhile, the polycondensation reaction of the product is caused by the excessively high reaction temperature; and the utility model adopts an unexpected ester exchange reaction system, which comprises a first ester exchange reaction kettle, a second ester exchange reaction kettle and a vacuum pump, the first ester exchange reaction kettle and the second ester exchange reaction kettle are connected in series through the pipeline, and the first ester exchange reaction kettle and the second ester exchange reaction kettle are connected with the same vacuum pump through the pipeline, that is, the ester exchange reaction is carried out twice continuously, so that the reaction conversion rate is improved, and meanwhile, the heating temperature of the first ester exchange reaction kettle is lower than that of the second ester exchange reaction kettle, so that the excessively high temperature in the same reaction kettle can be prevented, and the polycondensation reaction of the product is caused.

[0025] 2. The utility model discloses a two ester exchange reaction kettle with the same vacuum pump can make the reaction byproduct methanol be continuously extracted, thereby making the reactant more easily convert to the product, further improve the reaction conversion rate, simultaneously, under the negative pressure condition, can reduce the heating temperature of ester exchange reaction kettle, is favorable to the energy saving. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 The utility model discloses an ester exchange reaction system,

[0027] Figure 2 The utility model discloses an ester exchange reaction kettle,

[0028] 1 - first ester exchange reaction kettle, 2 - second ester exchange reaction kettle, 3 - vacuum pump,

[0029] a - kettle body, b - agitator, c - filler layer, d - jacket, h - coil, e - temperature controller, f1 - first feed inlet,

[0030] Second feed inlet, g - discharge port. DETAILED DESCRIPTION

[0031] In order to make the personnel in the technical field better understand the utility model scheme, below will combine the drawings in the embodiment of the utility model, clear, complete description to the technical scheme in the embodiment of the utility model, obviously, the described embodiment only is a part of the embodiment of the utility model, but is not all the embodiment. Based on the embodiment in the utility model, all other embodiments that the ordinary skill in the art obtains without making the creative labor should belong to the scope of the protection of the utility model.

[0032] It needs to be explained that the specification and the claims of the utility model and the above-mentioned terms "include" in the drawing are intended to cover the non-exclusive inclusion. In the utility model, the orientation or position relation that the terms "on", "under", "front", "back" etc. indicate is based on the orientation or position relation shown in the drawing. These terms are mainly for better describing the utility model and its embodiments, and are not used for limiting the indicated components must have a particular orientation. For the ordinary skill in the art, these terms can be understood in the specific meaning in the utility model according to the specific situation.

[0033] The utility model provides a kind of ester exchange reaction system of plastic alcoholysis, system includes first ester exchange reaction kettle 1, second ester exchange reaction kettle 2 and vacuum pump 3, first ester exchange reaction kettle 1 and second ester exchange reaction kettle 2 are connected by pipeline series connection between, first ester exchange reaction kettle 1 and second ester exchange reaction kettle 2 with same vacuum pump 3 are connected by pipeline,

[0034] The first ester exchange reaction kettle 1 is used for carrying out a first ester exchange reaction.

[0035] The second ester exchange reaction kettle 2 is used for carrying out a second ester exchange reaction.

[0036] The vacuum pump 3 is used for pumping out methanol in the first ester exchange reaction kettle 1 and the second ester exchange reaction kettle 2.

[0037] Figure 1 For the ester exchange reaction system of the utility model, the utility model provides a kind of ester exchange reaction system of plastic alcoholysis, system includes first ester exchange reaction kettle 1, second ester exchange reaction kettle 2 and vacuum pump 3, first ester exchange reaction kettle 1 and second ester exchange reaction kettle 2 are connected by pipeline series connection between, first ester exchange reaction kettle 1 and second ester exchange reaction kettle 2 with same vacuum pump 3 are connected by pipeline, wherein, first ester exchange reaction kettle 1 is used to carry out first ester exchange reaction to dimethyl phthalate and glycol, generate main product bis-hydroxyethyl terephthalate (BHET) and by-product methanol, but the conversion rate of reaction is only 88-90%, therefore, for further improving reaction conversion rate, the utility model uses second ester exchange reaction kettle 2 to carry out second ester exchange reaction, at this time, conversion rate is as high as 97-99%, vacuum pump 3 is used for pumping out by-product methanol in the first ester exchange reaction kettle 1 and the second ester exchange reaction kettle 2, to make reactant more easily convert to product direction, further improve reaction conversion rate, simultaneously, under negative pressure condition, the heating temperature of ester exchange reaction kettle can be reduced, and it is favorable to energy saving.

[0038] Optionally, Figure 2 For the structure diagram of ester exchange reaction kettle in the utility model, first ester exchange reaction kettle 1 and second ester exchange reaction kettle 2 include kettle body a, agitator b, packing layer c, jacket d, coil h, temperature controller e, feed inlet and discharge outlet g.

[0039] The main body structure of two ester exchange reaction kettles is identical, but heating temperature is different, i. e. the heating temperature of first ester exchange reaction kettle 1 is lower than that of second ester exchange reaction kettle 2, which can prevent that the heating temperature in the same reaction kettle is too high to cause the polycondensation reaction of product.

[0040] Optionally, kettle body a is cylindrical, and is made of stainless steel or carbon steel.

[0041] Kettle body a is made of corrosion-resistant material to adapt to high temperature, high pressure and chemical corrosion environment.

[0042] Optionally, agitator b is located at the top of kettle body a, and agitator b is paddle type.

[0043] The gap between the paddle of paddle type agitator b and kettle body a is small, so that materials can be fully mixed in the stirring process.

[0044] Optionally, the filler layer c is located at the upper part of the kettle body a, for increasing the contact area of the materials.

[0045] The filler layer c is composed of porous materials, which have large surface area and porosity, for increasing the contact area of the materials.

[0046] Optionally, the jacket d is located outside the kettle body a and wraps the kettle body a, and the coil h is located inside the kettle body a, both of which are used for heating the materials in the kettle body a.

[0047] The jacket d is filled with heating medium between the jacket d and the kettle body a, which is heated by external heat source, so as to transfer heat to the materials in the ester exchange reactor; the coil h is located inside the kettle body a, which can directly heat the materials.

[0048] Optionally, the temperature controller e is located at the top of the kettle body a, for controlling the heating temperature of the ester exchange reactor.

[0049] The temperature controller e can monitor and accurately control the heating temperature of the ester exchange reactor in real time, so as to ensure that the reaction is carried out under the expected conditions.

[0050] Optionally, the heating temperature of the first ester exchange reactor 1 is 130-160℃, and the equilibrium conversion rate of the ester exchange reaction is 88-90%.

[0051] The heating temperature of the first ester exchange reactor 1 is lower than that of the second ester exchange reactor 2, which can prevent the heating temperature from being too high in the same reactor, causing the polycondensation reaction of the product.

[0052] Optionally, the heating temperature of the second ester exchange reactor 2 is 160-180℃, and the equilibrium conversion rate of the ester exchange reaction is 97-99%.

[0053] The heating temperature of the second ester exchange reactor 2 is increased, which can increase the equilibrium conversion rate of the ester exchange reaction.

[0054] Optionally, the kettle body a has one feeding port at the top and the side wall, respectively, which are respectively marked as the first feeding port f1 and the second feeding port f2, the first feeding port f1 is used for externally adding materials, and the second feeding port f2 is used for transferring materials between the ester exchange reactors.

[0055] The first feeding port f1 is used for externally adding materials, and the second feeding port f2 is used for transferring materials between the ester exchange reactors.

[0056] Optionally, the kettle body a has one discharging port g at the bottom, the discharging port g of the first ester exchange reactor 1 is connected with the second feeding port f2 of the second ester exchange reactor 2.

[0057] The design can realize material transfer between the ester exchange reaction kettles, and the main product BHET is finally discharged from the discharge port g of the second ester exchange reaction kettle 2.

[0058] Alternatively, the top of the first ester exchange reaction kettle 1 and the top of the second ester exchange reaction kettle 2 are respectively connected with the same vacuum pump 3 through pipes.

[0059] The design can realize simultaneous extraction of the by-product methanol in the two ester exchange reaction kettles, so that the reactants are more easily converted to the product, and the reaction conversion rate is further improved.

[0060] The above is only a preferred embodiment of the present application, and is not intended to limit the present application in any other form, and any modification made according to the technical essence of the present application still falls within the scope of the present application.

Claims

1. A plastic alcoholysis ester exchange reaction system characterized by, The system comprises a first transesterification reactor (1), a second transesterification reactor (2) and a vacuum pump (3), the first transesterification reactor (1) and the second transesterification reactor (2) are connected in series by pipelines, the first transesterification reactor (1) and the second transesterification reactor (2) are connected with the same vacuum pump (3) by pipelines, The first transesterification reactor (1) is used for carrying out a first transesterification reaction. The second transesterification reactor (2) is used for carrying out a second transesterification reaction. The vacuum pump (3) is used for extracting methanol in the first transesterification reactor (1) and the second transesterification reactor (2).

2. The system of claim 1, wherein, The first transesterification reactor (1) and the second transesterification reactor (2) both comprise a reactor body (a), a stirrer (b), a packing layer (c), a jacket (d), a coil (h), a temperature controller (e), a feed inlet and a discharge outlet (g).

3. The system of claim 2, wherein, The reactor body (a) is cylindrical and made of stainless steel or carbon steel.

4. The system of claim 2, wherein, The stirrer b is located at the top of the reactor body a, and the stirrer (b) is paddle type.

5. The system of claim 2, wherein, The packing layer c is located at the upper part of the reactor body a, which is used to increase the contact area of the material.

6. The system of claim 2, wherein, The jacket (d) is located outside the reactor body (a) and wraps the reactor body (a), and the coil (h) is located inside the reactor body (a), both the jacket (d) and the coil (h) are used to heat the material in the reactor body (a).

7. The system of claim 2, wherein, The temperature controller (e) is located at the top of the reactor body (a) and is used to control the heating temperature of the transesterification reactor.

8. The system of claim 2, wherein, The top and side wall of the reactor body (a) each have one feed inlet, which are respectively marked as the first feed inlet (f1) and the second feed inlet (f2), the first feed inlet (f1) is used for external addition of material, and the second feed inlet (f2) is used for transferring material between the transesterification reactors.

9. The system of claim 8, wherein, The bottom of the reactor body (a) has one discharge outlet (g), and the discharge outlet (g) of the first transesterification reactor (1) is connected with the second feed inlet (f2) of the second transesterification reactor (2).

10. The system of claim 1, wherein, The top of the first transesterification reactor (1) and the top of the second transesterification reactor (2) are respectively connected with the same vacuum pump (3) by pipelines.

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