A device for preparing pentaerythritol by continuous condensation reaction
By combining a continuous condensation reaction system and an enhanced unit with a plug flow reactor, the problems of uneven mixing and insufficient control precision in the intermittent stirred tank reactor system were solved, achieving efficient and stable production of pentaerythritol, improving conversion rate and yield, and reducing energy consumption.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- NANJING YANCHANG REACTION TECH RES INST CO LTD
- Filing Date
- 2025-04-25
- Publication Date
- 2026-07-14
Smart Images
Figure CN224485950U_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of pentaerythritol generation technology, specifically relating to an apparatus for preparing pentaerythritol via a continuous condensation reaction. Background Technology
[0002] Pentaerythritol is an important organic chemical raw material widely used in resin, coating, chemical, and pharmaceutical industries. It is primarily used to produce lubricants, plasticizers, surfactants, emulsifiers, pharmaceuticals, pesticides, and explosives. Currently, deep-processed pentaerythritol products are under development, including initiators for polyester polyols, components for flame-retardant coatings, intermediates for epoxy crosslinking agents, stabilizers for polyvinyl chloride, intermediates for oil-modified amino surface coatings (amino alkyd resins), olefin antioxidants, and pentaerythritol triacrylates. Pentaerythritol phosphate and phosphite esters are used as flame retardants, antioxidants, or heat stabilizers in polymer production, while pentaerythritol acrylates are widely used in radiation-cured coatings and fast-drying printing inks, and are also used in the manufacture of water-soluble alkyd resins. Its polymer emulsions can be used as adhesives.
[0003] Currently, pentaerythritol production mainly relies on batch stirred tank condensation reaction systems. Although this technology is relatively mature, it still has some problems. First, the mixing and mass transfer of various reactants and catalysts in batch stirred tank reactors is poor, and the contact and dispersion of formaldehyde, acetaldehyde, and catalyst are uneven, easily forming temperature gradients or uneven concentrations. This can lead to side reactions such as condensation of formaldehyde and acetaldehyde and formaldehyde self-polymerization, reducing product yield. In addition, the control precision within batch stirred tank reactor reaction systems is limited, making it impossible to precisely control the amount of materials added, reaction time, and reaction temperature for each batch, resulting in unstable product quality for each batch. Furthermore, the operation of batch reaction systems is cumbersome and requires significant manual labor.
[0004] In view of the above, this utility model is hereby proposed. Utility Model Content
[0005] The primary objective of this invention is to provide an apparatus for the continuous condensation reaction to prepare pentaerythritol. This apparatus utilizes a continuous condensation reaction system to achieve the preparation of pentaerythritol. The continuous reaction process allows for a continuous feed of reactants and a continuous output of products, thereby significantly improving reaction efficiency and product quality stability. Furthermore, this invention employs an enhanced unit to achieve efficient mixing of reactants and precise temperature control within the reaction system, thus shortening reaction time and further improving reaction efficiency. The enhanced unit also ensures rapid and uniform mixing of reactants, preventing localized overheating or excessively high concentrations and reducing the occurrence of side reactions. Meanwhile, the continuous reaction of this invention allows for precise control of reaction parameters under continuous material flow conditions, enabling the conversion rate of acetaldehyde to reach 99%-100%, the yield of pentaerythritol to reach 92%-98%, and the yield of the more valuable dipentaerythritol to reach 0.5-5%. In addition, the continuous reaction can precisely control the reactant ratio, reducing the excess demand for formaldehyde and thus improving the utilization rate of raw materials. Furthermore, this invention uses a plug flow reactor to further complete the finishing reaction of pentaerythritol condensation, minimizing the backmixing of materials already generated in the enhanced reactor and further reducing the generation of by-products.
[0006] In order to achieve the above-mentioned objectives of this utility model, the following technical solution is adopted:
[0007] An apparatus for the continuous condensation reaction to prepare pentaerythritol includes a booster reaction tower and a plug flow reactor connected in sequence. A booster unit is located at the bottom of the booster reaction tower, and an acetaldehyde inlet is located below the booster unit. An alkali inlet, a formaldehyde inlet, and a circulation inlet are sequentially arranged above the booster reaction tower from top to bottom. A discharge port is located at the bottom of the booster reaction tower. A spray layer is located at the top of the booster reaction tower and connected to the alkali inlet. A liquid level sensor is located 0.2m-2m below the spray layer.
[0008] Preferably, the liquid level sensor is located 0.8m below the spray layer.
[0009] This invention utilizes a continuous condensation reaction apparatus to prepare pentaerythritol, thereby achieving continuous production of pentaerythritol. This improves the condensation reaction efficiency of the reactants formaldehyde, acetaldehyde, and alkaline solution. It not only enables continuous condensation reaction production of pentaerythritol but also further optimizes reaction parameters, reduces by-product formation, increases product yield, and reduces raw material consumption. The main design employs a combination of a booster unit and a plug-flow reactor, significantly improving reaction efficiency, product quality, and product yield. The booster unit uses high-speed shearing of the reactants to achieve molecular-level mixing of various reactants and catalysts, solving the problem of… To address the limited mass transfer issues in existing reactor technologies, a plug flow reactor was incorporated, allowing materials to flow in a piston-like manner within the reactor. This prevents backmixing and avoids over-reaction and the generation of byproducts. Simultaneously, the combination of the enhanced unit and the plug flow reactor enables more precise control of the reaction process. The enhanced unit allows for instantaneous mixing of reactants, eliminating localized overheating and achieving segmented temperature control, thus further optimizing the reaction path. Furthermore, the plug flow reactor allows for a longer residence time of reactants, precisely matching the kinetics of condensation reactions and preventing insufficient or excessive condensation that could lead to product defects. The conversion rate and purity are reduced. In this invention, the residence time of the reactants in the intensified unit is 0.5-2 hours, and the reaction conversion rate after treatment by the intensified unit is 75%-85%. Subsequently, in order to further improve the conversion rate of the product, the reactants will undergo further reaction in a plug flow reactor. At this time, the residence time of the reactants in the plug flow reactor is 0.05-1 hour. After further condensation reaction in the plug flow reactor, the reaction conversion rate can be increased by 15%-25%. Thus, the combined effect of the two processes significantly improves the conversion rate of the reactants. In addition, the setting of the intensified unit can effectively avoid... The continuous flow reactor, designed to prevent formaldehyde disproportionation, effectively avoids the formation of byproducts. Furthermore, the combination of the enhanced unit and the plug flow reactor results in higher overall heat transfer efficiency. This combination also allows for precise control of the raw material ratio, reducing excess formaldehyde demand and significantly improving raw material utilization. Therefore, compared to traditional batch pentaerythritol production systems, the continuous pentaerythritol production system provided by this invention offers higher production efficiency and precise control of parameters such as temperature, pressure, and material ratio to improve product purity and yield, reduce side reactions, and lower energy consumption.
[0010] Compared to traditional production methods, the continuous pentaerythritol production reaction system of this invention further refines reaction parameters by incorporating a liquid level sensor. This achieves precise control, efficient mass transfer, safety, stability, and energy conservation. The liquid level sensor is an essential core component in the continuous pentaerythritol production reaction system, whereas it is typically unnecessary in traditional batch reaction systems. This is because continuous reactors require maintaining a real-time balance between reactant feed and product discharge. The liquid level sensor monitors the liquid level in real time, linking feed and discharge to ensure a constant reaction volume and thus ensure the reaction proceeds fully. Therefore, this invention utilizes a liquid level sensor positioned 0.2m-2m below the spray layer, preferably at 0.8m. The excellent results achieved are due to the fact that 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. The feed rate can be adjusted through real-time feedback of liquid level data, avoiding problems such as excessively high 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 provide real-time feedback on the liquid level height in the reactor. However, 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, leading to misjudgment of the liquid level. In addition, the opening size of each spray nozzle in the spray layer of this invention is 0.1-5mm, which allows the catalyst alkali solution sprayed by the spray layer to be quickly and evenly dispersed.
[0011] Preferably, as a further feasible option, an external circulation system is provided outside the enhanced reaction tower, the external circulation system including a heat exchanger and an external circulation pump; the external circulation pump is connected to the discharge port; a heat exchanger inlet is provided above the enhanced unit, the heat exchanger is connected to the heat exchanger inlet, and the heat exchanger inlet leads into the enhanced unit.
[0012] Preferably, as a further feasible option, an external circulation outlet is provided between the heat exchanger and the external circulation pump, and the external circulation outlet is connected to the plug flow reactor.
[0013] Preferably, as a further feasible option, both the alkali inlet and the circulating inlet are connected to the enhanced reaction tower via a preheater.
[0014] Preferably, as a further feasible option, the plug flow reactor is provided with a plug flow reactor inlet and a plug flow reactor outlet on both sides, the plug flow reactor inlet is connected to the external circulation outlet, and a formic acid inlet is provided on the plug flow reactor outlet; the plug flow reactor outlet is connected to the separation tower.
[0015] Preferably, as a further feasible option, a reboiler is connected to the outer side of the bottom of the separation tower, a reboiler outlet is provided at the bottom of the separation tower and connected to the reboiler, and a formaldehyde outlet is provided at the top of the separation tower.
[0016] In the continuous pentaerythritol preparation apparatus of this invention, acetaldehyde, a reactant, is introduced into the enhanced reaction tower through an acetaldehyde inlet located at the bottom of the enhanced reaction tower. It mixes with formaldehyde, which has been preheated by a preheater and introduced through a formaldehyde inlet located at the top of the enhanced reaction tower. Simultaneously, alkali solution is introduced into the enhanced reaction tower through an alkali solution inlet located at the top of the enhanced reaction tower. The alkali solution is sprayed through a spray layer connected to the alkali solution inlet, thus ensuring uniform dispersion of the catalyst. Simultaneously, formaldehyde and acetaldehyde are introduced into the enhanced reaction unit and broken into small droplets, increasing the interphase area between them. After being catalyzed by the sprayed catalyst, the enhanced reaction proceeds. Subsequently, the reaction liquid gradually... As the reaction tower gradually fills, the external circulation pump draws a portion of the reaction liquid from the outlet at the bottom of the tower. After heat exchange in the heat exchanger, a portion returns to the tower through the circulation inlet at the top, while the other portion flows into the subsequent plug flow reactor for further reaction to improve the conversion rate. After the reaction is complete in the plug flow reactor, the reaction liquid flows out and mixes with the formic acid introduced from the formic acid inlet before flowing into the separation tower to recover excess formaldehyde. The formaldehyde after being processed in the separation tower flows from the top of the separation tower into the preheater for preheating before flowing back into the reaction tower for recycling. The crude pentaerythritol product obtained from the bottom of the tower will then be processed further.
[0017] This invention reduces the temperature and pressure during the reaction by using a continuous production method, and achieves a conversion rate of 99%-100% for the reaction raw material acetaldehyde and a yield of 92%-98% for pentaerythritol, of which the yield of the valuable dipentaerythritol is 0.5%-5%.
[0018] Compared with the prior art, the beneficial effects of this utility model are as follows:
[0019] (1) The present invention provides an apparatus for preparing pentaerythritol by continuous condensation reaction. The apparatus achieves 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 produced, thereby greatly improving the reaction efficiency. At the same time, the present invention also achieves a high conversion rate of raw materials and maintains a high yield of pentaerythritol by strengthening the reactor in series with a plug flow reactor. In addition, the continuous reaction of the present invention can achieve precise control of reaction parameters under the condition of continuous material flow, so that the raw material conversion rate can reach 99%-100% and the yield can reach 92%-98%, of which the content of the more valuable dipentaerythritol in the product reaches 0.5-5%. In addition, the continuous reaction can accurately control the reactant ratio, reduce the excess demand of formaldehyde, thereby improving the utilization rate of raw materials. Furthermore, the present invention improves the heat transfer efficiency by adopting a strengthened unit in the continuous reaction system, thereby reducing the reaction energy consumption. Attached Figure Description
[0020] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:
[0021] Figure 1 This is a structural diagram of an apparatus for preparing pentaerythritol via a continuous condensation reaction according to the present invention.
[0022] The attached diagram lists the components represented by each number as follows:
[0023] 1. Enhanced reaction tower; 2. External circulation pump; 3. Heat exchanger; 4. Preheater; 5. Plug flow reactor; 6. Separation tower; 7. Reboiler; 8. Spray layer. Detailed Implementation
[0024] The technical solution of this utility model will be clearly and completely described below with reference to the accompanying drawings and specific embodiments. However, those skilled in the art will understand that the embodiments described below are only some embodiments of this utility model, not all embodiments, and are only used to illustrate this utility model, and should not be regarded as limiting the scope of this utility model. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall be followed. Where the manufacturers of reagents or instruments are not specified, they are all conventional products that can be purchased commercially.
[0025] In the description of this utility model, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings and are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.
[0026] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.
[0027] To more clearly illustrate the technical solution of this utility model, the following description is provided in the form of specific embodiments.
[0028] Example 1
[0029] Please see Figure 1 As shown, this utility model is an apparatus for preparing pentaerythritol by continuous condensation reaction, including 1. an enhanced 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; and 9. an enhanced unit.
[0030] The continuous condensation reaction process for preparing pentaerythritol is as follows: Acetaldehyde is introduced into the enhanced reaction tower 1 at a rate of 196 kg / h through the acetaldehyde inlet located at the bottom of the enhanced reaction tower 1. It is mixed with formaldehyde introduced through the formaldehyde inlet located at the top of the enhanced reaction tower 1 after preheating by the preheater 3. Simultaneously, sodium hydroxide catalyst is introduced into the enhanced reaction tower 1 through the alkali inlet located at the top of the enhanced reaction tower 1. The molar ratio of formaldehyde, acetaldehyde, and sodium hydroxide is 4.5:1:1. Sodium hydroxide is sprayed through the spray layer 8 connected to the sodium hydroxide inlet. Formaldehyde and acetaldehyde are simultaneously introduced into the enhanced reaction unit and thoroughly mixed with the sprayed catalyst for enhanced reaction. The enhanced reaction tower 1 is controlled at 70% liquid level, 53℃, 0.12 MPa, and a residence time of 1 hour. The external circulation pump 3 pumps water from the enhanced reaction tower... A portion of the reaction liquid is drawn from the outlet at the bottom of tower 1, and after heat exchange in heat exchanger 3, part of it returns to the enhanced reaction tower 1 through the circulating feed inlet on the enhanced reaction tower 1. The other part flows into the subsequent plug flow reactor 5 for further reaction. The temperature of the plug flow reactor is controlled at 50℃, the pressure at 0.11MPa, and the residence time at 0.2h 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 liquid flows out and mixes with the formic acid introduced from the formic acid feed inlet before flowing into the separation tower 6 to recover excess formaldehyde. The formaldehyde after being treated in the separation tower flows from the top of the separation tower 6 into the preheater for preheating and then flows back into the enhanced reaction tower 1 for recycling. The crude pentaerythritol product is collected from the bottom of the separation tower 6.
[0031] Example 2
[0032] The continuous condensation reaction process for preparing pentaerythritol is as follows: Acetaldehyde is introduced into the enhanced reaction tower 1 at a rate of 470 kg / h through the acetaldehyde inlet located at the bottom of the enhanced reaction tower 1. It is mixed with formaldehyde introduced through the formaldehyde inlet located at the top of the enhanced reaction tower 1 after preheating by the preheater 3. Simultaneously, the catalyst alkali solution is introduced into the enhanced reaction tower 1 through the alkali solution inlet located at the top of the enhanced reaction tower 1. The alkali solution is sprayed through the spray layer 8 connected to the alkali solution inlet. The molar ratio of formaldehyde, acetaldehyde, and sodium hydroxide is 8.5:2:1. Formaldehyde and acetaldehyde are simultaneously introduced into the enhanced reaction unit and thoroughly mixed with the sprayed catalyst for the enhanced reaction. The enhanced reaction tower 1 is controlled at 80% liquid level, 39℃, 0.2 MPa, and a residence time of 2 hours. The external circulation pump 3 pumps water from the bottom of the enhanced reaction tower 1. A portion of the reaction liquid is drawn from the outlet and heat-exchanged in heat exchanger 3. Part of it returns to the enhanced reaction tower 1 through the circulating feed inlet, while the other part flows into the subsequent plug flow reactor 5 for further reaction. The plug flow reactor is controlled at 37℃, 0.15MPa, and has a residence time of 0.6h to further improve the reaction conversion rate. Ultimately, 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 complete reaction in the plug flow reactor 5, the reaction liquid flows out and mixes with formic acid introduced through the formic acid feed inlet before flowing into separation tower 6 to recover excess formaldehyde. The formaldehyde after separation tower treatment flows from the top of separation tower 6 into the preheater for preheating before flowing back into the enhanced reaction tower 1 for recycling. Pentaerythritol crude product is collected from the bottom of separation tower 6.
[0033] Comparative Example 1
[0034] The specific implementation method is the same as in Example 1, except that a plug flow reactor is not set up.
[0035] Comparative Example 2
[0036] Pentaerythritol was prepared using a batch stirred tank reactor, a traditional technique.
[0037] Experimental Example 1: Measurement of Conversion Rate in the Examples and Comparative Examples
[0038] The conversion rate was measured using online chromatographic analysis, with online gas chromatographs installed at the inlet and outlet of the reactor.
[0039] The calculation formula is: Conversion rate = (1 − inlet reactant molar flow rate / outlet reactant molar flow rate) × 100%.
[0040] Experimental Example 2: Measurement of Yield in the Example and Comparative Examples
[0041] The reaction solution was concentrated by evaporation, cooled and crystallized, filtered, dried and weighed as a solid product.
[0042] The yield was then calculated using a formula.
[0043] The yield is calculated as follows: (Actual pentaerythritol molar amount / Theoretical pentaerythritol molar amount) × 100%.
[0044] Separation energy consumption in Experimental Example 3: Examples and Comparative Examples
[0045] Steam consumption: The steam flow rate entering the reboiler of the separation tower is detected in real time by a steam flow meter;
[0046] Steam consumption per ton of product = Steam flow rate / Flow rate of pentaerythritol (the product);
[0047] The measured data are shown in Table 1 below.
[0048] Table 1
[0049]
[0050] Therefore, as shown by the above data, the continuous condensation reaction apparatus for preparing pentaerythritol provided by this invention can achieve a conversion rate of 99%-100% and a yield of 92%-98%. Compared with traditional reactors, it has lower separation energy consumption. This invention mainly improves reaction efficiency, product quality, and product yield by combining a booster unit with a plug flow reactor. The booster unit performs high-speed shearing on the reactants, breaking them into small droplets, increasing the specific surface area, and maximizing the contact area between the two phases. This solves the problem of limited mass transfer in existing reactors. The plug flow reactor then allows the materials to flow in a piston-like manner within the reactor, preventing back-mixing and avoiding over-reaction and the generation of byproducts. Simultaneously, the setup of the booster unit and the plug flow reactor allows for more precise control of the reaction process. The booster unit enables instantaneous mixing of the reactants, thereby eliminating localized mixing. While achieving partial overheating, the system also achieves segmented temperature control, thereby further optimizing the reaction path. Furthermore, the plug flow reactor allows for a longer residence time of the reactants, precisely matching the condensation reaction kinetics to avoid insufficient or excessive condensation, which could lead to reduced product yield and purity. Additionally, the intensifier unit effectively prevents formaldehyde disproportionation, and the continuous flow characteristics of the plug flow reactor effectively prevent the generation of byproducts. The combination of the intensifier unit and the plug flow reactor results in higher overall heat transfer efficiency for the reaction system. Simultaneously, the combination allows for precise control of the raw material ratio, reducing excess formaldehyde demand and significantly improving raw material utilization. Therefore, compared to traditional batch pentaerythritol production systems, the continuous pentaerythritol production system provided by this invention has higher production efficiency and precisely controls parameters such as temperature, pressure, and material ratio to improve product purity and yield, reduce side reactions, and lower energy consumption.
[0051] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model, and are not intended to limit it. Although the utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this utility model.
Claims
1. An apparatus for the preparation of pentaerythritol via a continuous condensation reaction, characterized in that, The system comprises a sequentially connected enhanced reaction tower and a plug flow reactor. An enhanced reaction unit is located at the bottom of the enhanced reaction tower, and an acetaldehyde inlet is located below the enhanced reaction tower and below the enhanced reaction unit. From top to bottom, an alkali inlet, a formaldehyde inlet, and a circulation inlet are sequentially arranged above the enhanced reaction tower. An outlet is located at the bottom of the enhanced reaction tower. A spray layer is located at the top of the enhanced reaction tower and is connected to the alkali inlet. A liquid level sensor is located 0.2m-2m below the spray layer.
2. The apparatus for preparing pentaerythritol by continuous condensation reaction according to claim 1, characterized in that, The liquid level sensor is located 0.8m below the spray layer.
3. The apparatus for preparing pentaerythritol by continuous condensation reaction according to claim 1, characterized in that, 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. A heat exchanger inlet is provided above the enhanced unit. The heat exchanger is connected to the heat exchanger inlet and the heat exchanger inlet leads into the enhanced unit.
4. The apparatus for preparing pentaerythritol by continuous condensation reaction according to claim 3, characterized in that, An external circulation outlet is provided between the heat exchanger and the external circulation pump, and the external circulation outlet is connected to the plug flow reactor.
5. The apparatus for preparing pentaerythritol by continuous condensation reaction according to claim 1, characterized in that, Both the alkali inlet and the circulating inlet are connected to the enhanced reaction tower via a preheater.
6. The apparatus for preparing pentaerythritol by continuous condensation reaction according to claim 4, characterized in that, The plug flow reactor has a feed inlet and a discharge outlet on both sides. The feed inlet is connected to the external circulation outlet, and the discharge outlet is equipped with a formic acid feed inlet. The discharge outlet is connected to the separation tower.
7. The apparatus for preparing pentaerythritol by continuous condensation reaction according to claim 6, characterized in that, A reboiler is connected to the outside of the bottom of the separation tower. A reboiler outlet is provided at the bottom of the separation tower and is connected to the reboiler. A formaldehyde outlet is provided at the top of the separation tower.