Method and system for continuously producing industrial trimethylolpropane

Abstract

The invention provides a method and a system for continuous production of industrial trimethylolpropane, and the method comprises the following steps: S1, mixing n-butyraldehyde, formaldehyde, a basic catalyst, water and formic acid, and carrying out a connizaro reaction to generate trimethylolpropane to obtain a condensation liquid; s2, removing methanol and water from the condensation solution to obtain a concentrated solution; s3, extracting the concentrated solution with an organic solvent to obtain an oil phase and a water phase, washing the oil phase with water, then removing the solvent to obtain a crude TMP mixture, firstly removing heavy components from the crude TMP mixture, then removing light components from the crude TMP mixture, refining, purifying, granulating and packaging to obtain a TMP finished product. The continuous production method of industrial trimethylolpropane has the advantages of simple process flow, few side reactions, good product quality, high yield, less generated wastewater and low operation energy consumption, and can realize large-scale industrial continuous production of trimethylolpropane.

Description

Technical Field

[0001] The invention belongs to the technical field of chemical industry, and in particular relates to a method and a system for continuous production of industrial trimethylolpropane. Background Art

[0002] Trimethylolpropane, referred to as TMP, is an important chemical raw material and organic intermediate. It is mainly used in the production of alkyd resins and polyurethanes, and can also be used in the production of high-grade coatings, rosin esters, surfactants, fiber processing agents, printing inks, plasticizers and high-grade lubricants, etc. It can also be used as a resin chain extender, textile auxiliaries and heat stabilizer for polyvinyl chloride resins.

[0003] In industry, TMP is mainly produced by condensation reaction of n-butyraldehyde and formaldehyde under the action of alkaline catalyst, including two production processes: Cannizzaro process and hydrogenation process. The hydrogenation process has high requirements on production technology level, requires hydrogenation equipment in the production process, has high equipment pressure, and has high requirements on hydrogenation equipment and catalysts. It is rarely used in industry. Only BASF in Germany adopts hydrogenation process abroad. At present, sodium or calcium Cannizzaro process is mostly used at home and abroad. The calcium salt used in the calcium Cannizzaro process is difficult to handle, the process flow is long, the cost is high, and the calcium salt is easy to crystallize and block the pipeline, which is difficult to solve in industrial production. Most manufacturers use the sodium Cannizzaro process.

[0004] Advanced foreign technology has adopted continuous reactors to replace intermittent reactors. The yield of n-butyraldehyde can reach about 95%. The yield of intermittent reactors is slightly lower, and the best process yield is 92%.

[0005] my country began to research and develop trimethylolpropane technology in the 1960s. The small-scale trial production equipment built by the first few factories eventually stopped production due to backward technology, small scale, poor product quality and other reasons. In addition, several domestic research institutes such as Beijing Chemical Research Institute have also conducted small-scale or pilot studies, but they are still in the experimental stage because the engineering problems cannot be solved. Domestic production equipment mostly adopts intermittent production, with backward technology, high cost, poor quality, low production capacity, low yield, and higher unit consumption than foreign countries. In recent years, my country has relied on its own scientific research strength to develop and improve the production process and realize the continuous production of trimethylolpropane, but the scale is small and there are few manufacturers. At present, there are only Beijing Chemical Plant No. 3, Jilin Chemical Group Haite Company, Shanghai Nanda Chemical Plant and Shenyang Paint Plant, with a total output of less than 5,000 t / a.

[0006] Therefore, in view of the production status and market prospects of trimethylolpropane in my country, it is necessary to improve the existing technology and develop a large-scale industrial continuous production process with simple process, few side reactions, small post-processing workload, good product quality, high yield, low operating energy consumption and low production cost, so that my country's trimethylolpropane production equipment can be greatly developed, thereby making the technical level and product quality of the equipment enter the world's advanced ranks. Summary of the invention

[0007] In view of this, the present invention aims to provide a method and system for continuous production of industrial trimethylolpropane to solve at least one technical problem in the background technology.

[0008] To achieve the above object, the technical solution of the present invention is achieved as follows: A method for continuous production of industrial trimethylolpropane comprises the following steps: S1: n-butyraldehyde, formaldehyde, alkaline catalyst, water and formic acid are mixed to undergo Cannizzaro reaction to generate trimethylolpropane, thereby obtaining a condensation liquid; S2: concentrated solution obtained by removing methanol and water from the condensation solution; S3: The concentrate is extracted with an organic solvent to obtain an oil phase and an aqueous phase. The oil phase is washed with water and then the solvent is removed to obtain a crude TMP mixture. The crude TMP mixture is firstly removed from heavy components, and then from light components and refined and purified, and then granulated and packaged to obtain a TMP finished product.

[0009] Further, the reaction temperature of the Cannizzaro reaction in step S1 is 30-40° C., the pressure is 0.2-0.3 MPa, and the pH is 5-7; And / or, the alkaline catalyst in step S1 includes one or more of calcium hydroxide, calcium oxide, sodium hydroxide, trimethylamine, triethylamine, tetraethylisopentylethylenediamine, and tetraphenylethylenediamine; Preferably, the alkaline catalyst is sodium hydroxide.

[0010] Furthermore, after the condensed liquid in step S2 is partially methanol-removed by a methanol removal tower, the remaining methanol and most of the water are separated by a multi-effect evaporation system to obtain recovered methanol and concentrated liquid, and the separated water is returned to step S1 as a water raw material; Alternatively, the condensed liquid in step S2 is separated into methanol and water by a multi-effect evaporation system to obtain recovered methanol and concentrated liquid, and the separated water is returned to step S1 as a water raw material; Furthermore, in step S2, methanol and water are removed from the condensation liquid to obtain a concentrated liquid to produce methanol-containing process water, and methanol-containing process water is distilled to obtain methanol.

[0011] Further, the organic extractant in step S3 includes one or more of ethyl acetate, n-butyraldehyde, o-xylene, n-butanol, isobutanol, n-pentanol, isopentanol, n-hexanol, n-octanol, and 2-ethylhexanol; Preferably, the organic extractant is 2-ethylhexanol.

[0012] Furthermore, in step S3, the organic solvent in the solvent aqueous solution generated after the oil phase is washed with water is recovered; The recovered organic solvent is used in the extraction of the concentrated liquid and the organic solvent in step S3, and the separated water is evaporated multiple times to recover the effective components, and the separated water is used as the raw material of the water in step S1; Preferably, in step S3, the crude TMP mixture is firstly subjected to the removal of heavy components and the purified heavy components are firstly subjected to the recovery of TMP, and then the heavy components are recovered; Preferably, after the light components are removed from the crude TMP mixture in step S3, the light components and the solvent are separated; Preferably, the aqueous phase after extraction in step S3 is subjected to a sodium formate evaporation process, the evaporated water is recovered by methanol, the concentrated sodium formate crystals are precipitated, separated by a centrifuge, dehydrated by a dryer, and then weighed and packaged to obtain a sodium formate product.

[0013] The system used in the above-mentioned method for continuous production of industrial trimethylolpropane is characterized by comprising a raw material preparation system, a condensation kettle, a methanol removal tower, a multi-effect evaporation system, an extraction tower, a water washing tower, a solvent removal tower, a thin film evaporator, a TMP light component removal tower, a light component recovery tower, a TMP refining tower, a granulator, and a packaging machine connected in sequence; Or the raw material preparation system, condensation kettle, multi-effect evaporation system, extraction tower, water washing tower, desolventizing tower, thin film evaporator, TMP light component removal tower, light component recovery tower, TMP refining tower, granulator, and packaging machine are connected in sequence.

[0014] Furthermore, the methanol removal tower is connected to the methanol recovery tower, and the methanol recovery tower is connected to the raw material preparation system; The water washing tower is connected to the dilute solvent recovery tower, the dilute solvent recovery tower is connected to the multi-effect evaporation system; the dilute solvent recovery tower is connected to the extraction tower; The extraction tower is connected to the sodium formate evaporation system, and the sodium formate evaporation system is connected to the methanol recovery tower; the sodium formate evaporation system, the crystallization tank, the centrifuge, and the dryer are connected in sequence; The desolventizing tower is connected to the extraction tower; The TMP light component removal tower is connected to the light component recovery tower, and the light component recovery tower is connected to the extraction tower; The thin film evaporation tower and the TMP refining tower are respectively connected to the TMP recovery tower, and the TMP recovery tower is connected to the heavy component recovery tower.

[0015] Furthermore, it also includes a vacuum system, which is connected to the multiple-effect evaporation system, the sodium formate evaporation system, and the methanol recovery tower; It also includes a tail gas washing tower, which is used to collect and wash the tail gas from the multiple-effect evaporation system, the sodium formate evaporation system, the vacuum tail gas from the methanol recovery tower, the venting gas from the atmospheric pressure tank and the tail gas generated during the TMP production process until they meet the emission standards and then are discharged into the air, or enter the downstream waste gas treatment device for deep treatment.

[0016] Furthermore, the condensation kettle is a container with an internal nozzle and stirring, the reaction heat removal adopts an external circulation method, and the condensation kettle adopts a type of operation of two or more identical multi-kettles; Preferably, most of the towers in the tower equipment are sieve plate type, and a few are packed type; for towers that are easily blocked by polymers, large-aperture sieve plate towers are selected; Preferably, the granulator is a closed granulator.

[0017] Compared with the prior art, the method and system for continuous production of industrial trimethylolpropane described in the present invention have the following advantages: 1. The method for continuous production of industrial trimethylolpropane of the present application adopts the best raw material ratio, controls the appropriate reaction temperature and residence time, and obtains the maximum n-butyraldehyde reaction yield.

[0018] 2. In the method for continuous production of industrial trimethylolpropane of the present application, the concentration unit adopts countercurrent multi-effect evaporation technology, which can reduce the water content in the concentrate to a minimum, reduce the steam consumption of the concentration unit, reduce the load of subsequent units, and reduce energy consumption.

[0019] 3. The method for continuous production of industrial trimethylolpropane of the present application uses 2-ethylhexanol as an extractant to separate organic substances such as formate and TMP, thereby reducing the occurrence of side reactions during the extraction process.

[0020] 4. The method for continuous production of industrial trimethylolpropane of the present application uses extremely pure water to wash the crude TMP solution, thereby reducing the Fe 2+ content, reducing the occurrence of side reactions in the distillation process.

[0021] 5. The method for continuous production of industrial trimethylolpropane of the present application adopts high-efficiency structured packing to improve the separation effect of the tower.

[0022] 6. The method for continuous production of industrial trimethylolpropane of the present application optimizes the sodium formate production process, adds a drying system, has a short process flow, low energy consumption, and produces high-quality sodium formate.

[0023] 7. In the method for continuous production of industrial trimethylolpropane of the present application, granulation is completed in a dry and closed system, which can effectively prevent the product from absorbing moisture.

[0024] 8. The method for continuous production of trimethylolpropane for industrial use of the present application has a simple process flow, few side reactions, good product quality, high yield, little wastewater generation, and low operating energy consumption, and can realize large-scale industrial continuous production of trimethylolpropane. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings: Figure 1 The present invention is a schematic diagram of an apparatus for a method for continuous production of industrial trimethylolpropane according to an embodiment of the present invention.

[0026] Description of reference numerals: 1. Raw material preparation system; 2. Condensation kettle; 3. Methanol removal tower; 4. Methanol recovery tower; 5. Multi-effect evaporation system; 6. Extraction tower; 7. Water washing tower; 8. Dilute solvent recovery tower; 9. Solvent removal tower; 10. Thin film evaporator; 11. TMP light component removal tower; 12. Light component recovery tower; 13. TMP refining tower; 14. Granulator; 15. TMP recovery tower; 16. Heavy component recovery tower; 17. Sodium formate evaporation system; 18. Crystallization tank; 19. Centrifuge; 20. Dryer; 21. Packaging machine; 22. Vacuum system; 23. Tail gas washing tower. DETAILED DESCRIPTION

[0027] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0028] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are 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 cannot be understood as limiting the present invention. In addition, the terms "first", "second", and the like are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, features defined as "first", "second", and the like may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0029] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" 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 a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood by specific circumstances.

[0030] The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with embodiments.

[0031] like Figure 1 As shown, this embodiment provides a method for continuous production of industrial trimethylolpropane, involving a method for continuously producing industrial trimethylolpropane products using n-butyraldehyde and formaldehyde as raw materials through condensation reaction, multi-effect evaporation, extraction, water washing, solvent removal, light removal, heavy removal and other processes.

[0032] The invention comprises a raw material preparation system 1, a condensation kettle 2, a methanol removal tower 3, a methanol recovery tower 4, a multi-effect evaporation system 5, an extraction tower 6, a water washing tower 7, a dilute solvent recovery tower 8, a solvent removal tower 9, a thin film evaporator 10, a TMP light component removal tower 11, a light component recovery tower 12, a TMP refining tower 13, a granulator 14, a packaging machine 21, a TMP recovery tower 15, a heavy component recovery tower 16, a sodium formate evaporation system 17, a crystallization tank 18, a centrifuge 19, a dryer 20, a vacuum system 22, and a tail gas washing tower 23, which are connected in sequence.

[0033] A method for continuous production of industrial trimethylolpropane comprises the following steps: Butyraldehyde, formaldehyde, process water, liquid alkali and formic acid are pumped from storage tanks into respective metering tanks through pipelines.

[0034] The measured n-butyraldehyde, formaldehyde, alkali solution, process water and formic acid are pumped into the condensation reactor 2. Under the action of stirring and external circulation, the temperature, pressure and pH value are controlled to be certain to cause the Cannizzaro reaction to generate trimethylolpropane. The side reactions mainly include the disproportionation of formaldehyde to generate formic acid and methanol, the neutralization reaction of formic acid with excess alkaline catalyst to generate salt and water, and the reaction of n-butyraldehyde and formaldehyde to generate ditrimethylolpropane.

[0035] The condensed liquid is pumped to the methanol removal tower 3, where part of the methanol and water are removed from the top of the tower. The materials at the bottom of the tower enter the multi-effect evaporation system 5, where the methanol and most of the water are separated from the condensed liquid by countercurrent four-effect evaporation. The obtained concentrated liquid is a mixture of TMP, sodium formate, water, light components, heavy components, etc. The four-effect evaporation process makes full use of the water vapor evaporated at each stage as a heat source for feed preheating or reboiler to save energy. The high-temperature water vapor is cooled by latent heat and sensible heat and then returned to the raw material preparation system 1 as preparation water for raw material preparation.

[0036] The methanol and water at the top of the methanol removal tower 3 enter the methanol recovery tower 4 to separate the methanol and water to obtain recovered methanol, and the separated water returns to the raw material preparation system 1 as preparation water for the preparation of raw materials.

[0037] The concentrated liquid separated by the multiple-effect evaporator is pumped from the storage tank to the extraction tower 6, and after extraction with the organic solvent 2-ethylhexanol, an oil phase and an aqueous phase are formed. The oil phase is TMP, light components, heavy components, solvents, a small amount of sodium formate, etc., and the aqueous phase is sodium formate and water. The oil phase enters the water washing tower 7 to remove most of the solvent, and then enters the desolventizing tower 9 to further remove the solvent to obtain a crude TMP mixture containing a small amount of solvent, light components, and heavy components.

[0038] The solvent aqueous solution at the bottom of the water washing tower 7 enters the dilute solvent recovery tower 8, and the solvent recovered from the top of the tower is returned to the extraction tower 6 for recycling. The water separated at the bottom of the tower is returned to the multi-effect evaporation system 5, and the effective components carried by the water washing process are recovered through secondary multi-effect evaporation to improve the product yield.

[0039] The solvent separated by the desolventizing tower 9 is returned to the extraction tower 6 for recycling.

[0040] The crude TMP mixture containing a small amount of solvent, light components and heavy components is pumped to the thin film evaporator 10, and the heavy components are removed from the bottom, and the crude TMP containing light components is evaporated and enters the TMP light component removal tower 11. The light components are removed from the top of the tower. The light components contain a small amount of solvent and enter the light component recovery tower 12. The small amount of solvent is separated from the light components and returned to the extraction tower 6 for recycling. The bottom material of the TMP light component removal tower 11 enters the TMP refining tower 13, and the TMP product is extracted from the top of the tower and sent to the granulator 14 and the packaging machine 21 for granulation and packaging to obtain the TMP finished product.

[0041] A small amount of heavy components are removed from the bottom of the TMP refining tower 13, and mixed with the heavy components separated by the thin film evaporator 10 and enter the TMP recovery tower 15. The recovered TMP returns to the TMP refining tower 13 for further distillation, and the heavy components enter the heavy component recovery tower 16 to obtain high value-added ditrimethylolpropane and other heavy components, which are sent to the ditrihydroxy recovery unit for purification and recovery.

[0042] The aqueous phase after extraction enters the sodium formate evaporation process. The evaporated extraction water contains a small amount of methanol and is sent to the methanol recovery tower 4 to recover the methanol. The concentrated sodium formate is crystallized in the crystallizer 18, separated by the centrifuge 19 and dehydrated by the dryer 20, and then weighed and packaged to obtain the finished sodium formate.

[0043] The vacuum system 22 is used to form a vacuum in processes such as multiple-effect evaporation, sodium formate evaporation, and distillation that need to be operated under vacuum conditions.

[0044] The tail gas washing tower 23 is used to collect the tail gas generated in the TMP production process, such as evaporation tail gas, distillation vacuum tail gas, atmospheric pressure tank venting gas, etc., and wash it until it meets the emission standards and then discharge it, or enter the downstream waste gas treatment device for deep treatment.

[0045] The condensed liquid of the reaction can directly enter the multi-effect evaporation system 5 by bypassing the methanol removal tower 3. The methanol removal tower 3 can be selectively set according to the situation to save investment and energy consumption.

[0046] The water separated from the dilute solvent recovery tower 8 is returned to the multi-effect evaporation system 5, and the effective components carried by the water washing can be recovered by secondary multi-effect evaporation to improve the product yield.

[0047] The water separated from the multi-effect evaporation system 5 and the methanol recovery tower 4 is returned to the raw material configuration system and used as configuration water for configuration of raw materials, thereby saving water.

[0048] The solvents separated by the dilute solvent recovery tower 8, the desolventizing tower 9 and the light component recovery tower 12 are all returned to the extraction tower 6 to be used as circulating solvent to extract the target product, thereby reducing the consumption of fresh solvent.

[0049] The catalyst used for the condensation reaction is a basic catalyst such as calcium hydroxide, calcium oxide, sodium hydroxide, trimethylamine, triethylamine, tetraethylisopentylethylenediamine, tetraphenylethylenediamine, etc., and sodium hydroxide is preferred in the present invention.

[0050] The extractant is one or more of ethyl acetate, n-butyraldehyde, o-xylene, n-butanol, isobutanol, n-pentanol, isopentanol, n-hexanol, n-octanol, 2-ethylhexanol, etc., and 2-ethylhexanol is preferred in the present invention.

[0051] The condensation reactor 2 is a container with internal spray pipes and stirring, and has corresponding strict design size requirements according to different production scales. The reaction heat removal adopts external circulation. In order to ensure the reliability of larger devices, two or more identical multi-reactor operation types can be adopted.

[0052] Most towers are sieve plate type, and a few are packed type. For towers that are easily blocked by polymers, choose large-aperture sieve plate towers.

[0053] The granulator 14 is a core device that affects the moisture content of trimethylolpropane. In order to ensure that the granulation can be carried out continuously, stably and safely, the granulator 14 is preferably a closed type.

[0054] In the present invention, taking a 50,000 tons / year trimethylolpropane device as an example, the purity of the raw material n-butyraldehyde is 99.5wt%, the purity of formaldehyde is 37wt%, 42wt% sodium hydroxide solution and 85wt% formic acid solution are selected, the reaction temperature is controlled to be 30-40°C, the pressure is 0.2-0.3MPa, and the pH is 5-7. The condensation liquid is subjected to countercurrent four-effect evaporation to obtain a concentrated solution, 99.5wt% 2-ethylhexanol is used for extraction and extremely pure water is used for washing. The operating pressure of the extraction tower 6 and the water washing tower 7 is about 0.1MPa, and the temperature is about 65°C. After washing, the solvent content in the crude TMP is about 1.3%, the light component content is about 2.5wt%, the heavy component content is about 7.3wt%, and the TMP content is about 88.9wt%. The crude TMP is refined by thin film evaporation, light removal, heavy removal, etc. to obtain a TMP product, and the operating pressure of the thin film evaporator 10 and the distillation tower is controlled at 0.001-0.005MPa. The purity of the trimethylolpropane product produced is ≥99.0wt%, the hydroxyl value is ≥1235mgKOH / g, the acidity (calculated as HCOOH) is ≤0.002wt%, the ash content is ≤0.005wt%, the moisture content is ≤0.05wt%, and the color is ≤10APHA (Pt-Co), which meets the HG / T 4122-2020 industrial superior product standard. Compared with the existing process, the product yield is increased by 15~20%, and the comprehensive energy consumption is reduced by 18~25%.

[0055] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for continuous production of industrial trimethylolpropane, characterized in that: The steps include: S1: n-butyraldehyde, formaldehyde, alkaline catalyst, water and formic acid are mixed to undergo Cannizzaro reaction to generate trimethylolpropane, thereby obtaining a condensation liquid; S2: concentrated solution obtained by removing methanol and water from the condensation solution; S3: The concentrate is extracted with an organic solvent to obtain an oil phase and an aqueous phase. The oil phase is washed with water and then the solvent is removed to obtain a crude TMP mixture. The crude TMP mixture is firstly removed from heavy components, and then from light components and refined and purified, and then granulated and packaged to obtain a TMP finished product.

2. The method for continuous production of industrial trimethylolpropane according to claim 1, characterized in that: The reaction temperature of the Cannizzaro reaction in step S1 is 30-40° C., the pressure is 0.2-0.3 MPa, and the pH is 5-7; And / or, the alkaline catalyst in step S1 includes one or more of calcium hydroxide, calcium oxide, sodium hydroxide, trimethylamine, triethylamine, tetraethylisopentylethylenediamine, and tetraphenylethylenediamine; Preferably, the alkaline catalyst is sodium hydroxide.

3. The method for continuous production of industrial trimethylolpropane according to claim 1, characterized in that: In step S2, after the condensation liquid passes through the methanol removal tower to remove part of the methanol, the remaining methanol and most of the water are separated by the multi-effect evaporation system to obtain recovered methanol and concentrated liquid, and the separated water is returned to step S1 as a water raw material; Alternatively, in step S2, the condensed liquid is separated into methanol and water by a multi-effect evaporation system to obtain recovered methanol and concentrated liquid, and the separated water is returned to step S1 as a water raw material.

4. The method for continuous production of industrial trimethylolpropane according to claim 3, characterized in that: In step S2, methanol and water are removed from the condensation liquid to obtain a concentrated liquid to generate methanol-containing process water, and methanol-containing process water is distilled to obtain methanol.

5. The method for continuous production of industrial trimethylolpropane according to claim 1, characterized in that: The organic extractant in step S3 includes one or more of ethyl acetate, n-butyraldehyde, o-xylene, n-butanol, isobutanol, n-pentanol, isopentanol, n-hexanol, n-octanol, and 2-ethylhexanol; Preferably, the organic extractant is 2-ethylhexanol.

6. The method for continuous production of industrial trimethylolpropane according to claim 1, characterized in that: The organic solvent in the solvent aqueous solution produced after the oil phase is washed with water in step S3 is recovered; The recovered organic solvent is used in the extraction of the concentrated liquid and the organic solvent in step S3, and the separated water is evaporated multiple times to recover the effective components, and the separated water is used as the raw material of the water in step S1; Preferably, in step S3, the crude TMP mixture is firstly subjected to the removal of heavy components and the purified heavy components are firstly subjected to the recovery of TMP, and then the heavy components are recovered; Preferably, after the light components are removed from the crude TMP mixture in step S3, the light components and the solvent are separated; Preferably, the aqueous phase after extraction in step S3 is subjected to a sodium formate evaporation process, the evaporated water is recovered by methanol, the concentrated sodium formate crystals are precipitated, separated by a centrifuge, dehydrated by a dryer, and then weighed and packaged to obtain a sodium formate product.

7. The device used in the method for continuous production of industrial trimethylolpropane according to any one of claims 1 to 6, characterized in that: It includes the raw material preparation system, condensation kettle, methanol removal tower, multi-effect evaporation system, extraction tower, water washing tower, solvent removal tower, thin film evaporator, TMP light component removal tower, light component recovery tower, TMP refining tower, granulator, and packaging machine connected in sequence; Or the raw material preparation system, condensation kettle, multi-effect evaporation system, extraction tower, water washing tower, desolventizing tower, thin film evaporator, TMP light component removal tower, light component recovery tower, TMP refining tower, granulator, and packaging machine are connected in sequence.

8. The device according to claim 7, characterized in that: The methanol removal tower is connected to the methanol recovery tower, and the methanol recovery tower is connected to the raw material preparation system; The water washing tower is connected to the dilute solvent recovery tower, the dilute solvent recovery tower is connected to the multi-effect evaporation system; the dilute solvent recovery tower is connected to the extraction tower; The extraction tower is connected to the sodium formate evaporation system, and the sodium formate evaporation system is connected to the methanol recovery tower; the sodium formate evaporation system, the crystallization tank, the centrifuge, and the dryer are connected in sequence; The desolventizing tower is connected to the extraction tower; The TMP light component removal tower is connected to the light component recovery tower, and the light component recovery tower is connected to the extraction tower; The thin film evaporation tower and the TMP refining tower are respectively connected to the TMP recovery tower, and the TMP recovery tower is connected to the heavy component recovery tower.

9. The device according to claim 7, characterized in that: It also includes a vacuum system, which is connected to the multiple-effect evaporation system, the sodium formate evaporation system, and the methanol recovery tower; It also includes a tail gas washing tower, which is used to collect and wash the tail gas from the multiple-effect evaporation system, the sodium formate evaporation system, the vacuum tail gas from the methanol recovery tower, the venting gas from the atmospheric pressure tank and the tail gas generated during the TMP production process until they meet the emission standards and then are discharged into the air, or enter the downstream waste gas treatment device for deep treatment.

10. The device according to claim 7, characterized in that: The condensation kettle is a container with internal spray pipe and stirring, the reaction heat removal adopts external circulation, and the condensation kettle adopts the type of two or more identical multi-kettle operation; Preferably, the tower in the tower equipment is a sieve plate type or a packing type; for towers that are easily blocked by polymers, a large-aperture sieve plate tower is selected; Preferably, the granulator is a closed granulator.

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