Device for preparing pentaerythritol through continuous condensation reaction and reaction method thereof

Abstract

The invention provides a device for preparing pentaerythritol through continuous condensation reaction and a reaction method thereof. The device comprises an enhanced reaction tower and a plug flow reactor which are connected in sequence, wherein a strengthening unit is arranged at the bottom in the strengthening reaction tower, an acetaldehyde feeding hole is formed in the lower part of the strengthening reaction tower, and the acetaldehyde feeding hole is formed in the lower part of the strengthening unit; an alkali liquor feeding hole, a formaldehyde feeding hole and a circulating feeding hole are sequentially formed in the upper part of the enhanced reaction tower from top to bottom; a discharge hole is formed in the bottom of the enhanced reaction tower; a spray layer is arranged at the top in the enhanced reaction tower, the spray layer is connected with the alkali liquor feed port, a liquid level sensor is arranged below the spray layer, and the liquid level sensor is arranged at a position 0.2-2 m below the spray layer; preferably, the liquid level sensor is arranged at the position 0.8 m below the spraying layer. According to the device disclosed by the invention, reactants are continuously fed, and products are continuously produced, so that the reaction rate is obviously accelerated.

Description

Technical Field

[0001] The present invention belongs to the technical field of pentaerythritol production processes, and particularly relates to an apparatus for continuously condensing to produce pentaerythritol and a reaction method thereof. Background Art

[0002] Pentaerythritol is an important organic chemical raw material, widely used in industrial sectors such as resins, coatings, chemicals, and pharmaceuticals. Pentaerythritol is mainly used to produce lubricants, plasticizers, surfactants, emulsifiers, medicines, pesticides, explosives, etc. Currently, deep-processed products of pentaerythritol are being developed, including initiators for polyester polyols, components of flame-retardant coatings, epoxy crosslinker intermediates, PVC stabilizers, intermediates for oil-modified amino surface coatings (amino alkyd resins), olefin antioxidants, and pentaerythritol triacrylate. The phosphates and phosphites of pentaerythritol are used as flame retardants, antioxidants, or heat stabilizers in polymer production, while pentaerythritol acrylate is widely used in radiation-cured coatings and fast-drying printing inks, and is also used to manufacture water-soluble alkyd resins, and its polymer emulsion can be used as an adhesive.

[0003] Currently, the production of pentaerythritol mainly relies on an intermittent stirred-tank condensation reaction system. Although this technology is relatively mature, there are still some problems. Firstly, in the intermittent stirred reaction kettle, the mass transfer effect of various reaction raw materials and catalysts is poor, and the contact and dispersion of formaldehyde, acetaldehyde, and the catalyst are uneven, easily forming temperature gradients or concentration non-uniformities, which in turn trigger side reactions such as the condensation of formaldehyde and acetaldehyde and the self-polymerization of formaldehyde, reducing the product yield. Secondly, the control accuracy in the intermittent stirred-tank reaction system is limited, and it is impossible to precisely control the addition amount of each batch of materials, the reaction time, and the reaction temperature to be exactly the same, so the product quality obtained from each batch of reactions is unstable. In addition, the operation of the intermittent reaction system is cumbersome, and the manual labor intensity is relatively large.

[0004] In view of this, the present invention is specifically proposed. Summary of the Invention

[0005] The first object of the present invention is to provide a device for preparing pentaerythritol by continuous condensation reaction. The device realizes the preparation of pentaerythritol by adopting a continuous condensation reaction system. The continuous reaction allows the reactants to be continuously fed and the products to be continuously output, thereby greatly improving the reaction efficiency and improving the stability of product quality. At the same time, the present invention also uses an enhanced unit to achieve efficient mixing of reactants and precise temperature control in the reaction system, thereby shortening the reaction time and further improving the reaction efficiency. The enhanced unit can make the reactants quickly and evenly mixed to avoid the problem of local overheating or excessive concentration, and reduce the occurrence of side reactions. At the same time, under the condition of continuous material flow, the reaction parameters of the continuous reaction of the present invention can be precisely controlled, so that the conversion rate of the raw material acetaldehyde can reach 99%-100%, the yield of the product pentaerythritol can reach 92%-98%, and the yield of the more valuable dipentaerythritol in the product can reach 0.5~5%; in addition, the continuous reaction can accurately control the ratio of reactants, reduce the excessive demand for formaldehyde, and thus improve the utilization rate of raw materials. In addition, the present invention further completes the clean-up reaction of pentaerythritol condensation through the plug flow reactor, avoids the back mixing of the generated materials in the enhanced reactor as much as possible, and further reduces the generation of by-products.

[0006] The second object of the present invention is to provide a continuous condensation method for preparing pentaerythritol, which can reduce the excess proportion of formaldehyde during the continuous preparation process, thereby improving the utilization rate of raw materials and reducing separation energy consumption.

[0007] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are particularly adopted: A device for preparing pentaerythritol by continuous condensation reaction, comprising an enhanced reaction tower and a plug flow reactor connected in sequence; wherein an enhanced unit is arranged at the bottom of the enhanced reaction tower, an acetaldehyde feed port is arranged below the enhanced reaction tower, and the acetaldehyde feed port is located below the enhanced unit; an alkali solution feed port, a formaldehyde feed port and a circulation feed port are arranged in sequence from top to bottom above the enhanced reaction tower; a discharge port is arranged at the bottom of the enhanced reaction tower; a spray layer is arranged at the top of the enhanced reaction tower, the spray layer is connected to the alkali solution feed port, a liquid level sensor is arranged below the spray layer, and the liquid level sensor is arranged 0.2m-2m below the spray layer; Preferably, the liquid level sensor is arranged 0.8 m below the spray layer.

[0008] In the present invention, a device for continuously condensing pentaerythritol is adopted to achieve the continuous production of pentaerythritol, improve the condensation reaction efficiency of reactants formaldehyde, acetaldehyde and lye, not only can realize the continuous condensation reaction of pentaerythritol production, but also can further optimize the reaction parameters, reduce the generation of by-products, improve the product yield and reduce the raw material consumption; among which, the design of combining a strengthening unit and a plug flow reactor is mainly adopted to significantly improve the reaction efficiency, product quality and product yield. The reaction materials are subjected to high-speed shearing by the strengthening unit to achieve molecular-level mixing of various reactants and catalysts, solving the problem of limited mass transfer in the reaction kettle in the prior art. Subsequently, combined with the plug flow reactor, the materials show piston-like flow in the reactor, preventing backmixing between the materials to avoid the generation of by-products due to overreaction; at the same time, the setting of the strengthening unit and the plug flow reactor can better and accurately control the reaction process. The setting of the strengthening unit enables the reactant raw materials to be instantaneously mixed, so as to eliminate local overheating while achieving the purpose of segmented temperature control to further optimize the reaction path. And the plug flow reactor can make the residence time of the reactants longer, accurately matching the kinetic requirements of the condensation reaction to avoid insufficient reaction or over-condensation, resulting in a decrease in product yield and purity. In the present invention, the residence time of the reaction materials in the strengthening unit is 0.5 - 2 h, and at this time, the reaction conversion rate is 75% - 85% after being treated by the strengthening unit. Subsequently, in order to further improve the conversion rate of the product, the reaction materials will further react in the plug flow reactor. At this time, the reaction residence time of the reaction materials in the plug flow reactor is 0.05 - 1 h. After the further condensation reaction in the plug flow reactor, the reaction conversion rate can be increased by 15% - 25%. Thus, through the combined action of the two, the conversion rate of the reactants is greatly improved; in addition, the setting of the strengthening unit can well avoid the disproportionation of formaldehyde, and at the same time, the continuous flow characteristics of the plug flow reactor can also well prevent the generation of by-products; and the combination of the strengthening unit and the plug flow reactor can make the heat transfer efficiency of the overall reaction system higher, and at the same time, the combination of the two can accurately control the raw material ratio to reduce the excessive demand for formaldehyde, greatly improving the utilization rate of the raw materials; therefore, compared with the traditional intermittent production system of pentaerythritol, the continuous production system of pentaerythritol provided by the present invention has higher production efficiency, and accurately regulates parameters such as temperature, pressure, and material ratio to improve the product purity and yield, reduce side reactions, and reduce energy consumption.

[0009] Compared with the traditional production method, the reaction system for the continuous production of pentaerythritol of the present invention further precisely controls the reaction parameters by setting a liquid level sensor, achieving the purposes of precise control, efficient mass transfer, safe and stable operation, and energy conservation and environmental protection. In the reaction system for the continuous production of pentaerythritol, the liquid level sensor is an essential core component, while it is usually not used in the traditional batch reaction system. This is because the continuous reactor needs to maintain the real-time balance of reactant feeding and product discharging, and the liquid level sensor can ensure a constant reaction volume by monitoring the liquid level in real time and linking the feeding and discharging, thus ensuring the full progress of the reaction. Therefore, in the present invention, by using a liquid level sensor and setting it at a position 0.2 m - 2 m below the spray layer, preferably at 0.8 m, the achieved effect is excellent. This is because the liquid level sensor can further ensure that the liquid level in the enhanced reaction tower is at the optimal position, thereby maintaining the optimal reaction volume and residence time, adjusting the feeding rate through the real-time feedback of the liquid level data, and avoiding the problems of excessive local concentration or uneven reaction in the enhanced reaction tower. At the same time, when the liquid level sensor and the spray layer are within a suitable range, the liquid level sensor can better feedback the liquid level height in the reactor in real time. If the distance between the spray layer and the liquid level sensor is too close, the liquid sprayed by the spray layer may directly interfere with the measurement of the liquid level sensor, resulting in misjudgment of the liquid level. At the same time, the opening size of each spray orifice in the spray layer of the present invention is 0.1 - 5 mm, so that the catalyst lye can be quickly and evenly dispersed after being sprayed by the spray layer.

[0010] Preferably, as a further feasible solution, an external circulation system is provided outside the enhanced reaction tower. The external circulation system includes a heat exchanger and an external circulation pump; the external circulation pump is connected to the discharge port; an inlet of the heat exchanger is provided above the enhanced unit, and the heat exchanger is connected to the inlet of the heat exchanger, and the inlet of the heat exchanger leads into the enhanced unit.

[0011] Preferably, as a further feasible solution, an external circulation discharge port is provided between the heat exchanger and the external circulation pump, and the external circulation discharge port is connected to the plug flow reactor.

[0012] Preferably, as a further feasible solution, both the lye feed port and the circulation feed port are connected to the enhanced reaction tower through a preheater.

[0013] Preferably, as a further feasible solution, a plug flow reactor feed port and a plug flow reactor discharge port are respectively provided on both sides of the plug flow reactor. The plug flow reactor feed port is connected to the external circulation discharge port, and a formic acid feed port is provided on the plug flow reactor discharge port; the plug flow reactor discharge port is connected to a separation tower.

[0014] Preferably, as a further feasible solution, a reboiler is connected to the outside of the bottom of the separation column. A reboiler discharge port is provided at the bottom of the separation column. The reboiler discharge port is connected to the reboiler. A formaldehyde discharge port is provided at the top of the separation column.

[0015] In the device for continuously preparing pentaerythritol of the present invention, the reactant acetaldehyde is introduced into the enhanced reaction column through the acetaldehyde feed port provided below the enhanced reaction column, and is mixed with formaldehyde introduced through the formaldehyde feed port provided on the enhanced reaction column after being preheated by a preheater. At the same time, the catalyst lye will be introduced into the enhanced reaction column through the lye feed port provided on the enhanced reaction column. The lye is sprayed through the spray layer connected to the lye feed port, and the catalyst is evenly dispersed through the spray layer. At the same time, formaldehyde and acetaldehyde are broken into small droplets after being introduced into the enhanced unit, increasing the phase interface area between the two. After being catalyzed by the catalyst after spraying, an enhanced reaction is carried out. Subsequently, the reaction liquid gradually fills the enhanced reaction column. At this time, the external circulation pump will extract a part of the reaction liquid from the discharge port provided at the bottom of the enhanced reaction column, heat it through a heat exchanger, and then return a part of it to the enhanced reaction column through the circulation feed port provided on the enhanced reaction column, while the other part will flow into the subsequent plug flow reactor for further reaction to further improve the reaction conversion rate. After the reaction is complete in the plug flow reactor, the reaction material flows out, and is mixed with formic acid introduced through the formic acid feed port and then flows into the separation column to recover the excess formaldehyde. The formaldehyde treated by the separation column will flow into the preheater from the top of the separation column and then flow into the enhanced reaction column for recycling. The crude pentaerythritol product obtained at the bottom of the column will enter the subsequent treatment.

[0016] The present invention also provides a method for continuously condensing and reacting to prepare pentaerythritol by using the device for continuously condensing and reacting to prepare pentaerythritol as described above, including the following steps: Continuously add formaldehyde, acetaldehyde and lye for enhanced reaction, then perform plug flow tailing, and then introduce formic acid and lye to obtain pentaerythritol.

[0017] Preferably, as a further feasible solution, the lye catalyst is any one of lye solution, potassium hydroxide solution, calcium hydroxide solution, trimethylamine, and triethylamine; furthermore, the mass concentration of the catalyst solution is 10%-50%.

[0018] Preferably, as a further feasible solution, the molar ratio of formaldehyde, lye, and acetaldehyde is (4.5-8.5):(1.1-2):1.

[0019] Preferably, as a further feasible solution, the reaction temperature is 20-80°C, and the reaction pressure is 0-0.5 MPa.

[0020] In the preparation method of the present invention, the temperature and pressure during the reaction are reduced through continuous production, and the conversion rate of the reaction raw material acetaldehyde is 99%-100%, and the yield of pentaerythritol reaches 92%-98%. Among them, the yield of valuable dipentaerythritol in the product is 0.5%-5%.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) The device for preparing pentaerythritol by continuous condensation reaction provided by the present invention realizes the preparation of pentaerythritol by adopting a continuous condensation reaction system. Through continuous reaction, the reactants are continuously fed and the products are continuously produced, thus greatly improving the reaction efficiency. At the same time, the present invention also strengthens the reactor in series with a plug flow reactor to achieve a high conversion rate of raw materials while maintaining a high yield of the product pentaerythritol. At the same time, under the condition of continuous material flow in the continuous reaction of the present invention, the reaction parameters can be accurately controlled, so that the raw material conversion rate can reach 99%-100% and the yield can reach 92%-98%. Among them, the content of dipentaerythritol with higher value in the product reaches 0.5-5%. In addition, the continuous reaction can accurately control the reactant ratio, reduce the excessive demand for formaldehyde, thereby improving the raw material utilization rate, and the present invention improves the heat transfer efficiency by adopting a strengthening unit in the continuous reaction system, thereby reducing the reaction energy consumption.

[0022] (2) The continuous condensation for preparing pentaerythritol provided by the present invention reduces the excessive use of formaldehyde, thereby improving the raw material utilization rate and reducing the separation energy consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] By reading the following detailed description of the preferred embodiments, various other advantages and benefits will become clear to those of ordinary skill in the art. The drawings are only for the purpose of showing the preferred embodiments and are not considered to be a limitation of the present invention. Moreover, throughout the drawings, the same reference numerals are used to represent the same components. In the drawings: Figure 1 is a structural diagram of the device for preparing pentaerythritol by continuous condensation reaction of the present invention; In the drawings, the list of components represented by each reference numeral is as follows: 1. Strengthened reaction tower; 2. External circulation pump; 3. Heat exchanger; 4. Preheater; 5. Plug flow reactor; 6. Separation tower; 7. Reboiler; 8. Spray layer. DETAILED DESCRIPTION OF THE INVENTION

[0024] The technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings and specific embodiments. However, those skilled in the art will understand that the following described embodiments are some embodiments of the present invention, rather than all embodiments, and are only used to illustrate the present invention and should not be construed 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 making creative efforts belong to the scope of protection of the present invention. For those conditions not specified in the embodiments, they are carried out according to conventional conditions or conditions recommended by the manufacturer. Those reagents or instruments not specified by the manufacturer can be obtained as conventional products through commercial purchase.

[0025] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as limiting the present invention. In addition, the terms "first", "second", "third" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance.

[0026] In the description of the present invention, it should be noted that unless otherwise clearly specified and limited, the terms "installation", "connection", "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; 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 communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0027] In order to more clearly illustrate the technical solution in the present invention, it will be described below in the form of specific embodiments.

[0028] Embodiment 1 Please refer to Figure 1 As shown, the present invention is a device for continuously condensing and reacting to prepare pentaerythritol, which includes 1. a strengthened reaction tower; 2. an external circulation pump; 3. a heat exchanger; 4. a preheater; 5. a plug flow reactor; 6. a separation tower; 7. a reboiler; 8. a spray layer; 9. a strengthening unit.

[0029] The reaction process for preparing pentaerythritol by this continuous condensation reaction is as follows: Acetaldehyde as a reactant is introduced into the enhanced reaction tower 1 through the acetaldehyde feed port provided below the enhanced reaction tower 1 at a dosage of 196 kg / h, and is mixed with formaldehyde introduced through the formaldehyde feed port provided on the enhanced reaction tower 1 after being preheated by the preheater 3. At the same time, the catalyst sodium hydroxide is introduced into the enhanced reaction tower 1 through the lye feed port provided on the enhanced reaction tower 1. The molar ratio of formaldehyde, acetaldehyde to sodium hydroxide is 4.5:1:1. Sodium hydroxide is sprayed through the spray layer 8 connected to the sodium hydroxide feed port. At the same time, formaldehyde and acetaldehyde are introduced into the enhanced unit and fully mixed with the sprayed catalyst for enhanced reaction. The enhanced reaction tower 1 is controlled at a liquid level of 70%, the temperature is controlled at 53 °C, the pressure is controlled at 0.12 MPa, and the residence time is 1 h. The external circulation pump 3 extracts a part of the reaction liquid from the discharge port provided at the bottom of the enhanced reaction tower 1, exchanges heat through the heat exchanger 3, and then a part of it returns to the enhanced reaction tower 1 through the circulating feed port provided on the enhanced reaction tower 1, while the other part flows into the subsequent plug flow reactor 5 for further reaction. The plug flow reactor is controlled at a temperature of 50 °C, a pressure of 0.11 MPa, and a residence time of 0.2 h to further improve the reaction conversion rate. Finally, the raw material conversion rate in the enhanced reactor 1 is 85%, and the raw material conversion rate at the outlet of the plug flow reactor 5 is 99.5%. After the reaction is complete in the plug flow reactor 5, the reaction material flows out, and is mixed with formic acid introduced through the formic acid feed port and then flows into the separation tower 6 to recover the excessive formaldehyde. The formaldehyde after being treated by the separation tower flows from the top of the separation tower 6 into the preheater and then flows into the enhanced reaction tower 1 for recycling. The crude pentaerythritol product is withdrawn from the bottom of the separation tower 6.

[0030] Example 2 The reaction process for preparing pentaerythritol by this continuous condensation reaction is as follows: Acetaldehyde as a reactant is introduced into the enhanced reaction tower 1 through the acetaldehyde feed port provided below the enhanced reaction tower 1 at a dosage of 470 kg / h, and is mixed with formaldehyde introduced through the formaldehyde feed port provided on the enhanced reaction tower 1 after being preheated by the preheater 3. Meanwhile, the catalyst lye will be introduced into the enhanced reaction tower 1 through the lye feed port provided on the enhanced reaction tower 1, and the lye is sprayed through the spray layer 8 connected to the lye feed port. The molar ratio of formaldehyde, acetaldehyde to sodium hydroxide is 8.5:2:1. Meanwhile, formaldehyde and acetaldehyde are simultaneously introduced into the enhanced unit and fully mixed with the sprayed catalyst for enhanced reaction. The enhanced reaction tower 1 is controlled at 80% liquid level, the temperature is controlled at 39 °C, the pressure is controlled at 0.2 MPa, and the residence time is 2 h. The external circulation pump 3 will draw a part of the reaction liquid from the discharge port provided at the bottom of the enhanced reaction tower 1, and after heat exchange through the heat exchanger 3, a part of it will return to the enhanced reaction tower 1 through the circulating feed port provided on the enhanced reaction tower 1, while the other part will flow into the subsequent plug flow reactor 5 for further reaction. The plug flow reactor is controlled at a temperature of 37 °C, a pressure of 0.15 MPa, and a residence time of 0.6 h to further improve the reaction conversion rate. Finally, the raw material conversion rate in the enhanced reactor 1 is 81%, and the raw material conversion rate at the outlet of the plug flow reactor 5 is 99.8%. After the reaction is complete in the plug flow reactor 5, the reaction liquid flows out, and at the same time, it is mixed with formic acid introduced through the formic acid feed port and then flows into the separation tower 6 to recover the excessive formaldehyde. The formaldehyde after being treated by the separation tower will flow from the top of the separation tower 6 into the preheater for preheating and then flow into the enhanced reaction tower 1 for recycling. The crude pentaerythritol product is taken out from the bottom of the separation tower 6.

[0031] Comparative Example 1 The specific implementation method is the same as that of Example 1, and the only difference is that the plug flow reactor is not set.

[0032] Comparative Example 2 Pentaerythritol is prepared by using a traditional batch stirred tank in the prior art.

[0033] Experimental Example 1 Measurement of conversion rates in examples and comparative examples The conversion rate is measured by using on-line chromatographic analysis method. On-line gas chromatographs are installed at the inlet and outlet of the reactor respectively; The calculation formula is conversion rate = (1 - molar flow rate of inlet reactant / molar flow rate of outlet reactant) × 100%.

[0034] Experimental Example 2 Measurement of yields in examples and comparative examples The reaction liquid is evaporated and concentrated, then cooled and crystallized. After filtering and drying the solid product, it is weighed; Subsequently, the yield is calculated through the calculation formula; Where the yield = (actual molar amount of pentaerythritol / theoretical molar amount of pentaerythritol) × 100% Experimental Example 3 Separation energy consumption in the examples and comparative examples Steam consumption: The steam flow rate entering the reboiler at the bottom of the separation column was detected in real time by a steam flowmeter; Steam consumption per ton of product = steam flow rate / flow rate of the product pentaerythritol; The measured data are shown in Table 1 below Table 1

[0035] Therefore, from the above data, it can be seen that the conversion rate of the device for continuously preparing pentaerythritol by condensation reaction provided by the present invention can reach 99% - 100%, and the yield reaches 92% - 98%. Compared with traditional reactors, the separation energy consumption is lower. The present invention mainly combines a strengthening unit and a plug - flow reactor in the design, which can significantly improve the reaction efficiency, product quality and product yield. The reaction materials are sheared at high speed by the strengthening unit to break the reactants into small droplets, increasing the specific surface area and maximizing the two - phase contact area, solving the problem of limited mass transfer in the reaction kettle of the prior art. Subsequently, combined with the plug - flow reactor, the materials show piston - type flow in the reactor, preventing back - mixing between the materials and avoiding the generation of by - products due to over - reaction. At the same time, the setting of the strengthening unit and the plug - flow reactor can better and precisely control the reaction process. The setting of the strengthening unit enables the reactant raw materials to be instantaneously mixed, eliminating local overheating while achieving the purpose of sectional temperature control, thereby further optimizing the reaction path. And the plug - flow reactor can make the residence time of the reactants longer, accurately matching the kinetic requirements of the condensation reaction to avoid insufficient reaction or over - condensation, resulting in a decrease in product yield and purity. In addition, the setting of the strengthening unit can well avoid the disproportionation of formaldehyde, and the continuous - flow characteristics of the plug - flow reactor can also well prevent the generation of by - products. Moreover, the combination of the strengthening unit and the plug - flow reactor can make the heat transfer efficiency of the overall reaction system higher, and the combination of the two can accurately control the raw material ratio, reducing the excessive demand for formaldehyde and greatly improving the utilization rate of raw materials. Therefore, compared with the traditional intermittent production system of pentaerythritol, the continuous production system of pentaerythritol provided by the present invention has higher production efficiency, and accurately regulates parameters such as temperature, pressure, and material ratio to improve product purity and yield, reduce side reactions, and lower energy consumption.

[0036] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than 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 they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An apparatus for preparing pentaerythritol by continuous condensation reaction, characterized in that, It includes a strengthened reaction tower and a plug flow reactor connected in sequence; wherein a strengthening unit is arranged at the bottom inside the strengthened reaction tower, an acetaldehyde feed inlet is arranged below the strengthened reaction tower, and the acetaldehyde feed inlet is located below the strengthening unit; a lye feed inlet, a formaldehyde feed inlet and a recycle feed inlet are sequentially arranged from top to bottom above the strengthened reaction tower; a discharge outlet is arranged at the bottom of the strengthened reaction tower; a spraying layer is arranged at the top inside the strengthened reaction tower, the spraying layer is connected to the lye feed inlet, and a liquid level sensor is arranged below the spraying layer, and the liquid level sensor is arranged at a position 0.2 m - 2 m below the spraying layer. Preferably, the liquid level sensor is arranged at a position 0.8 m below the spraying layer.

2. The apparatus for preparing pentaerythritol by continuous condensation reaction according to claim 1, characterized in that, An external circulation system is arranged outside the strengthened reaction tower, and the external circulation system includes a heat exchanger and an external circulation pump; the external circulation pump is connected to the discharge outlet; a heat exchanger feed inlet is arranged above the strengthening unit, the heat exchanger is connected to the heat exchanger feed inlet, and the heat exchanger feed inlet leads into the strengthening unit.

3. The apparatus for preparing pentaerythritol by continuous condensation reaction according to claim 2, characterized in that, An external circulation discharge outlet is arranged between the heat exchanger and the external circulation pump, and the external circulation discharge outlet is connected to the plug flow reactor.

4. The device for preparing pentaerythritol by continuous condensation reaction according to claim 1, characterized in that, Both the lye feed inlet and the recycle feed inlet are connected to the strengthened reaction tower through a preheater.

5. The device for preparing pentaerythritol by continuous condensation reaction according to claim 1, characterized in that, A plug flow reactor feed inlet and a plug flow reactor discharge outlet are respectively arranged on both sides of the plug flow reactor, the plug flow reactor feed inlet is connected to the external circulation discharge outlet, and a formic acid feed inlet is arranged on the plug flow reactor discharge outlet; the plug flow reactor discharge outlet is connected to a separation tower.

6. The apparatus for preparing pentaerythritol by continuous condensation reaction according to claim 5, characterized in that, A reboiler is connected to the outside of the bottom of the separation tower, a reboiler discharge outlet is arranged at the bottom of the separation tower, the reboiler discharge outlet is connected to the reboiler, and a formaldehyde discharge outlet is arranged at the top of the separation tower.

7. The reaction carried out by the device for continuously preparing pentaerythritol through condensation reaction according to any one of claims 1-6, characterized in that, It includes the following steps: Formaldehyde, acetaldehyde and lye are continuously added, after strengthened reaction and plug flow tailing, formic acid and lye are introduced, and then it is obtained.

8. The reaction carried out by the apparatus for preparing pentaerythritol through continuous condensation reaction according to claim 7, characterized in that, The lye catalyst is any one of lye solution, potassium hydroxide solution, calcium hydroxide solution, trimethylamine and triethylamine.

9. The reaction carried out by the apparatus for preparing pentaerythritol through continuous condensation reaction according to claim 7, characterized in that, The molar ratio of the formaldehyde, lye and acetaldehyde is (4.5 - 8.5) : (1.1 - 2) :

1.

10. The reaction carried out by the apparatus for preparing pentaerythritol through continuous condensation reaction according to claim 7, characterized in that, The temperature of the reaction is 20 - 80 °C, and the reaction pressure is 0 - 0.5 MPa.

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