Process for the hydrolysis of a trihydroxy recombinant component acetal and recovery of trimethylolpropane

Abstract

The present application relates to the technical field of resource recycling of chemical by-products, in particular to a method for hydrolysis of acetals in trihydroxy heavy components and recovery of trimethylolpropane, comprising a recovery tank, and the following steps: S1, solution treatment; S2, heating reaction; S3, solid-liquid separation; S4, solution distillation; S5, dissolution and purification; S6, washing and drying. The method is simple and does not produce salt: the traditional neutralization step is abandoned, the introduction of inorganic salt impurities such as sodium ions is avoided from the source, the purity of the obtained product is high, the subsequent wastewater treatment is simple; a solid acid catalyst is used, which is easy to separate and recover, can be reused, and realizes clean production; the TMP recovery rate is significantly improved; by-products can be effectively separated to obtain high-quality TMP crystals; at the same time, by setting a filtering bin, a washing pipe, a rotating rod, a heat supply pipe and a blast pipe, integrated treatment of filtering, washing and drying of the crystallized solution is realized.

Description

Technical Field

[0001] This invention relates to the field of resource recovery technology of chemical by-products, specifically a method for the hydrolysis of acetal and the recovery of trimethylolpropane from trihydroxy compounds. Background Technology

[0002] In the industrial production process of trimethylolpropane (TMP), the mother liquor from the distillation process is enriched with a large amount of acetal byproducts. These components are stable in content and have considerable reserves, possessing high value for resource recovery and reuse. Targeted separation and purification can effectively improve raw material utilization and reduce production losses.

[0003] However, existing technologies often use strong liquid acids (such as sulfuric acid) for hydrolysis, which must be neutralized with alkali to terminate the reaction and prevent equipment corrosion. This process inevitably introduces inorganic salts (such as sodium sulfate), resulting in impurities in the product, difficulties in subsequent separation, and the generation of high-salt wastewater.

[0004] Therefore, in order to solve the above problems, a method for hydrolysis of acetal and recovery of trimethylolpropane from trihydroxy compounds is proposed. Summary of the Invention

[0005] The purpose of this invention is to provide a method for the hydrolysis of acetal and the recovery of trimethylolpropane from trihydroxy compounds, so as to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a method for hydrolyzing acetal and recovering trimethylolpropane from trihydroxy compounds, comprising a recovery tank, wherein the recovery tank is internally equipped with a filter chamber, a washing pipe, a rotating rod, and a heating pipe, and a blower pipe is suspended at the bottom of the recovery tank; and further comprising the following steps:

[0007] S1. Solution treatment: Mix the mother liquid with the solid catalyst and add it to the reactor; the amount of solid superacid catalyst used is 5%-15% of the mass of the heavy components;

[0008] S2. Heating reaction: The reaction vessel is heated and stirred to obtain a reaction solution;

[0009] S3. Solid-liquid separation: Filter the solution after the reaction to remove unreacted solid catalyst; the temperature of the reaction solution during filtration is 70-80℃.

[0010] S4. Solution distillation: The acidic hydrolysate obtained above is subjected to stepwise distillation; the stepwise distillation includes distilling off most of the water under normal pressure and distilling under reduced pressure to obtain the main fraction, and the temperature is controlled at 120-150℃ and the vacuum degree is controlled at 500-1000Pa during the reduced pressure distillation.

[0011] S5. Dissolution and purification: Dissolve the trimethylolpropane main fraction obtained from distillation in an alcohol solvent and stir thoroughly, then wait for cooling and crystallization; or dissolve the fraction in methanol or ethanol and cool to 0-10℃ to crystallize.

[0012] S6. Washing and drying: The crystallized solution is filtered, washed and dried to obtain high-purity trimethylolpropane crystals; the obtained trimethylolpropane crystals have a color number ≤25, a content of 98.2~99.5%, and a moisture content of 0.02-0.10%.

[0013] The detailed process of the direct hydrolysis of acetal and recovery of trimethylolpropane from the trimethylolpropane component is as follows: 90 parts of the primary mother liquor of the trimethylolpropane component and 8 parts of solid superacid catalyst are added to a reaction vessel, stirred and heated to 80℃, and kept at this temperature for 2-8 hours. After the holding period, the mixture is filtered while hot to obtain an acidic hydrolysate. The water in the acidic hydrolysate is removed under a negative pressure of 900 Pa for 1 hour. The trimethylolpropane fraction is collected at a top temperature of 120-150℃, dissolved in ethanol, cooled to 0-5℃, crystallized, filtered, washed, and dried to obtain the trimethylolpropane product.

[0014] As a further step of this solution, the recycling tank includes a processing chamber, with a top chamber and a bottom chamber respectively connected and assembled above and below the processing chamber. A drain pipe is integrally installed in the center of the bottom of the bottom chamber, and a bracket is supported on the side of the processing chamber. Feed pipes are integrally installed in both sides of the rear end of the top chamber, and exhaust pipes are integrally installed uniformly around the top perimeter of the top chamber. The filter chamber is located at the top of the recycling tank, and the recycling tank and the filter chamber are integrally connected. The washing pipe is inserted and installed on the rear side wall of the top chamber, and the rotating rod is suspended in the center of the top chamber. The heating pipe is inserted into the lower right side wall of the recycling tank, and the blower pipe is suspended directly below the bottom edge of the bottom chamber.

[0015] The above-mentioned technical means enable integrated processing of filtration, washing and drying of the crystallized solution; at the same time, it facilitates the assembly and subsequent disassembly and maintenance of the recovery tank, filter chamber, washing pipe, rotating rod, heating pipe and blower pipe, making cleaning more convenient.

[0016] As a further step of this solution, a receiving tray is provided inside the filter chamber, and the receiving tray is inserted and assembled inside the filter chamber from the left side. The outer wall of the left side of the receiving tray and the outer wall of the filter chamber are fitted with a buckle. A filter screen frame is integrally fixed to the bottom wall inside the receiving tray, and a convex screen frame is integrally provided in the center of the filter screen frame. A lever is suspended at the bottom of the rotating rod, and the center of the lever is convex, corresponding to the convex screen frame. The bottom shape of the lever is the same as the cross-section of the filter screen frame and the convex screen frame.

[0017] The above-mentioned technical means enable the filtration of the crystallized solution, filter the crystalline solids, and facilitate the extraction and insertion of the filter material, making the operation more convenient.

[0018] As a further step of this solution, the inner end of the washing pipe is integrally connected with a spray pipe, and the spray pipe is in a horizontal spiral shape from the outside to the inside. The center of the spray pipe is hollow and sleeved outside the rotating rod, and the outer side of the spray pipe is supported by an upper side support, which is fixed to the inner wall of the top chamber.

[0019] The above-mentioned technical means facilitate the spraying and washing of the internally filtered crystalline material with alcohol-based cold liquid, making subsequent operations more convenient.

[0020] As a further step of this solution, a rotating sleeve is fitted on the upper part of the rotating rod, and the rotating sleeve is installed in the center of the top of the top compartment through a bearing. A worm gear is fixed on the outside of the rotating sleeve, and a worm is meshed on the rear side of the worm gear. A motor is connected to the side end of the worm, and a corresponding top plate is supported in the center of the top of the top compartment. The motor is supported on the surface of the top plate, and a cover is provided on the outside of the worm gear and the worm. A pull hole is opened at the top of the rotating rod.

[0021] The above-mentioned technical means facilitate the driving rotation of the rotating rod, which causes the lever to move the filter screen and the convex screen surface, making the filtering, washing and drying operations more convenient and less prone to clogging.

[0022] As a further step of this solution, the inner end of the heating pipe is integrally connected with an inner heating pipe, and the inner heating pipe is arranged in an S-shape horizontally from the outside to the inside. The outer wall of the inner heating pipe is supported by a lower side support, which is supported on the lower inner wall of the processing chamber.

[0023] The above-mentioned technical means facilitate the connection of a mold temperature controller to the outer end of the heating pipe. With the cooperation of the inner heating pipe, a heat medium is supplied to heat the bottom of the recovery tank, and then the hot air is blown upward by the subsequent blower pipe for drying.

[0024] As a further step of this solution, the bottom of the hopper is set in an arc-shaped recess, and a blower head is integrally connected around the bottom perimeter of the hopper. A connector is integrally connected to the right side of the bottom of the blower pipe. A plug groove for docking with the blower head is integrally connected to the top of the blower pipe. The blower head is set in a conical shape that is wider at the bottom and narrower at the top. The blower head is connected vertically, and a cap is suspended and supported on the top of the blower head.

[0025] By employing the aforementioned technical means, and with the cooperation of the connector, the blower is connected. Through the uniform arrangement of the air nozzles, the air is evenly blown upwards to push the heat generated by the heating pipe, thereby achieving drying and making operation and use more convenient.

[0026] Compared with the prior art, the beneficial effects of the present invention are:

[0027] 1. Through the corresponding process flow, the method is simple and salt-free: the traditional neutralization step is abandoned, avoiding the introduction of inorganic salt impurities such as sodium ions from the source, resulting in high-purity products and simple subsequent wastewater treatment; solid acid catalysts are used, which are easy to separate and recover, and can be reused, achieving clean production;

[0028] 2. Achieving efficient and selective hydrolysis of acetals under mild conditions through relatively gentle methods significantly improves TMP recovery; direct distillation combined with solvent crystallization effectively separates byproducts and yields high-quality TMP crystals.

[0029] 3. By setting up a filter chamber, washing pipe, rotating rod, heating pipe, and blower pipe, the system achieves integrated filtration, washing, and drying of the crystallized solution, making operation more convenient. Specifically, during filtration, the filter chamber assists in filtering the crystals, and the washing pipe, in conjunction with the alcohol solution, sprays and washes it, such as cold ethanol. Subsequently, the heating pipe and blower pipe work together to heat the crystals from below and blow air upwards to dry them. Furthermore, the rotating rod helps to move the material during filtration, washing, and drying, preventing clogging during filtration and ensuring more uniform and thorough washing and drying, thus improving operational efficiency.

[0030] 4. In addition to the above structural design, the combination and support assembly of the recycling tank facilitates disassembly, cleaning, and reassembly. At the same time, with the assistance of the filter chamber, the material after filtration, washing, and drying can be easily removed, which helps to improve the efficiency of operation and processing. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0032] Figure 1 This is a schematic diagram of the process flow of the present invention;

[0033] Figure 2 This is a frontal perspective three-dimensional schematic diagram of the overall structure of the present invention;

[0034] Figure 3 This is a bottom-view perspective view of the overall structure of the present invention;

[0035] Figure 4 This is a three-dimensional side view sectional diagram of the structure of the present invention;

[0036] Figure 5 This is a three-dimensional sectional view of a partial structure of the top compartment of the present invention.

[0037] Figure 6 This is a side view of the exploded three-dimensional assembly of a partial structure of the filter chamber of the present invention;

[0038] Figure 7 This is a top-view three-dimensional schematic diagram of a partial structure of the heating pipe of the present invention;

[0039] Figure 8 This is a three-dimensional sectional view of a partial structure of the bottom compartment of the present invention.

[0040] Figure 9 For the present invention Figure 4 Enlarged schematic diagram of the structure at point A in the middle.

[0041] In the diagram: 100, Recycling tank; 101, Processing chamber; 102, Top chamber; 103, Bottom chamber; 104, Drain pipe; 105, Support; 106, Feed pipe; 107, Exhaust pipe; 108, Top plate; 110, Filter chamber; 111, Receiving tray; 112, Lock; 113, Filter screen frame; 114, Convex screen frame; 120, Washing pipe; 121, Spray pipe; 122, Upper side support; 130, Rotating rod; 131, Actuator; 132, Rotating sleeve; 133, Worm gear; 134, Worm; 135, Motor; 136, Cover; 137, Pull hole; 140, Heating pipe; 141, Internal heating pipe; 142, Lower side support; 150, Blower pipe; 151, Connecting joint; 152, Air nozzle; 153, Insertion groove; 154, Cap. Detailed Implementation

[0042] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0043] Please see Figures 1-9 The present invention provides an embodiment of a method for the hydrolysis of acetal and the recovery of trimethylolpropane from trihydroxy compounds, comprising the following steps:

[0044] S1. Solution treatment: Mix the mother liquid with the solid catalyst and add it to the reactor; the amount of solid superacid catalyst used is 5%-15% of the mass of the heavy components;

[0045] S2. Heating reaction: The reaction vessel is heated and stirred to obtain a reaction solution;

[0046] S3. Solid-liquid separation: The solution after the reaction is filtered to remove unreacted solid catalyst; the temperature of the reaction solution during filtration is 70-80℃, and an acidic hydrolysate is obtained.

[0047] S4. Solution distillation: The acidic hydrolysate obtained above is subjected to stepwise distillation; the stepwise distillation includes distilling off most of the water under normal pressure and distilling under reduced pressure to obtain the main fraction, and the temperature is controlled at 120-150℃ and the vacuum degree is controlled at 500-1000Pa during the reduced pressure distillation.

[0048] S5. Dissolution and purification: Dissolve the trimethylolpropane main fraction obtained from distillation in an alcohol solvent and stir thoroughly, then wait for cooling and crystallization; or dissolve the fraction in methanol or ethanol and cool to 0-10℃ to crystallize.

[0049] S6. Washing and drying: The crystallized solution is filtered, washed and dried to obtain high-purity trimethylolpropane crystals; the obtained trimethylolpropane crystals have a color number ≤25, a content of 98.2-99.5%, and a moisture content of 0.02-0.10%.

[0050] The detailed process is as follows: 90 parts of the mother liquor of the trimethylolpropane fraction and 8 parts of the solid superacid catalyst are added to the reactor, stirred and heated to 80℃, and kept at this temperature for 2-8 hours. After the holding time is completed, the mixture is filtered while hot to obtain an acidic hydrolysate. The water in the acidic hydrolysate is removed under a negative pressure of 900Pa. After 1 hour of removal, the trimethylolpropane fraction is collected at a top temperature of 120-150℃. The trimethylolpropane fraction is dissolved in ethanol, cooled to 0-5℃, crystallized, filtered, washed and dried to obtain the trimethylolpropane product.

[0051] It also includes a recovery tank 100, which is internally equipped with a filter chamber 110, a washing pipe 120, a rotating rod 130, and a heating pipe 140. A blower pipe 150 is suspended at the bottom of the recovery tank 100. The recovery tank 100 includes a processing chamber 101, which is respectively connected to a top chamber 102 and a bottom chamber 103 by bolts, facilitating subsequent disassembly and reassembly. A drain pipe 104 is integrally installed in the center of the bottom of the bottom chamber 103, which facilitates connection to corresponding pipelines for drainage. A bracket 105 supports the side of the processing chamber 101, and feed pipes 106 are integrally connected to both sides of the rear end of the top chamber 102, allowing the introduction of the crystallized solution from the rear, which facilitates subsequent auxiliary operations. The top chamber 102 is uniformly and integrally connected with exhaust pipes 107 around its top perimeter, enabling ventilation and steam discharge during drying. The filter chamber 110 is located above the recovery tank 100, and the recovery tank 100 and the filter chamber 110 are integrally connected, facilitating material receiving, filtration, and subsequent washing and drying operations at the top. The washing pipe 120 is inserted into the rear side wall of the top chamber 102, the rotating rod 130 is suspended in the center of the top chamber 102, the heating pipe 140 is inserted into the lower right side wall of the recovery tank 100, and the blower pipe 150 is suspended directly below the bottom edge of the bottom chamber 103, realizing the combined assembly of the washing pipe 120, rotating rod 130, heating pipe 140, and blower pipe 150, thereby achieving integrated operation of filtration, washing, and drying.

[0052] As described in more detail in this embodiment, a receiving tray 111 is provided inside the filter chamber 110. The receiving tray 111 is inserted and assembled inside the filter chamber 110 from the left side. A latch 112 is installed on the outer left wall of the receiving tray 111 and the outer wall of the filter chamber 110 to facilitate the insertion and stable support of the receiving tray 111, and also to facilitate subsequent disassembly and pull-out. A filter screen frame 113 is integrally fixed to the bottom wall inside the receiving tray 111. A protruding mesh frame 114 is integrally provided in the center of the filter screen frame 113 to assist the receiving tray 111 in filtering and collecting materials. The crystals are also easy to handle in subsequent washing and drying operations. With the convex screen frame 114 in place, they are not easy to accumulate in the center. The bottom of the rotating rod 130 is equipped with a lever 131. The center of the lever 131 is convex, corresponding to the convex screen frame 114. The bottom shape of the lever 131 is the same as the cross-section of the filter screen frame 113 and the convex screen frame 114. This allows the rotating rod 130 to drive the lever 131 to push the material onto the surface of the filter screen frame 113 and the convex screen frame 114, which is less likely to cause blockage and is also conducive to uniform spray washing and drying of the side bottom.

[0053] As described in more detail in this embodiment, a spray pipe 121 is integrally connected to the inner end of the washing pipe 120. The spray pipe 121 is in a horizontal spiral shape from the outside to the inside, which realizes uniform spraying of washing liquid and is conducive to uniform washing in the future. The center of the spray pipe 121 is hollow and sleeved on the outside of the rotating rod 130. An upper support 122 is provided on the outside of the spray pipe 121 and fixed to the inner wall of the top chamber 102 to achieve stable support for the spray pipe 121. A rotating sleeve 132 is sleeved on the upper part of the rotating rod 130. The rotating sleeve 132 is installed in the center of the top of the top chamber 102 through a bearing. A worm gear 133 is fixed on the outside of the rotating sleeve 132. A worm 134 is meshed on the rear side of the worm gear 133. A motor 135 is connected to the side end of the worm 134. A corresponding top plate 108 is supported in the center of the top of the top chamber 102. The motor 135 is supported on the surface of the top plate 108. A cover 13 is provided on the outside of the worm gear 133 and the worm 134. 6. A pull hole 137 is provided at the top of the rotating rod 130. The rotating sleeve 132 is inserted with the cooperation of the bearing to realize the subsequent rotation of the rotating sleeve 132. That is, the worm gear 134 is driven by the motor 135 to rotate, which drives the worm wheel 133 to rotate, thereby realizing the rotation of the rotating sleeve 132. The lever 131 is inserted into the rotating sleeve 132. The upper part of the rotating sleeve 132 and the upper part of the lever 131 are assembled by bolts, which facilitates stable driving and also facilitates the removal of bolts when the receiving tray 111 is pulled out. The crossbar is inserted through the pull hole 137 to pry the rotating rod 130 up and down, so that the rotating sleeve 132 is disengaged from the receiving tray 111, which facilitates the insertion and removal of the receiving tray 111. At the same time, the setting of the top plate 108 facilitates the suspension support of the motor 135, avoiding direct heat during subsequent drying. Under the cover of the cover 136, it is convenient to maintain the worm wheel 133 and the worm gear 134.

[0054] As described in more detail in this embodiment, an inner heating pipe 141 is integrally connected to the inner end of the heating pipe 140. The inner heating pipe 141 is S-shaped and horizontally surrounds the bottom of the recovery tank 100 to achieve uniform heating. Specifically, it is connected to a mold temperature controller in conjunction with the heating pipe 140 to control the supply of heat transfer medium at the corresponding temperature. A lower support 142 supports the outer wall of the inner heating pipe 141, which rests on the lower inner wall of the processing chamber 101 for stable support. The bottom of the bottom chamber 103 is concave in an arc shape. A blower head 152 is integrally connected to the periphery of the bottom of the bottom chamber 103. A connector 151 is integrally connected to the right side of the bottom of the blower pipe 150, and a connector below the blower head 152 is integrally connected to the top of the blower pipe 150. The insertion slot 153 and the nozzle 152 are tapered with a wider bottom and a narrower top. The nozzle 152 is connected from top to bottom. The top of the nozzle 152 is suspended and supported by a cap 154. With the cooperation of the connector 151, it connects to the blower. With the cooperation of the blower pipe 150 and the insertion slot 153, air is blown into the inside of the nozzle 152 and the air is sprayed out from the top of the nozzle 152. With the assistance of the cap 154, it is not easy for liquid to enter from the top of the nozzle 152 during washing. At the same time, the internal heating pipe 141 above supplies heat to realize the blowing of hot air from bottom to top. With the cooperation of the exhaust pipe 107, the upper and lower air channels are realized to dry the crystals washed inside the material tray 111, so as to obtain the corresponding high content product.

[0055] Example 1

[0056] 1000g of the mother liquor of the trimethylolpropane fraction (91.86% water, pH=2.94) was taken, and 4g of solid superacid catalyst was added. The mixture was stirred at 80℃ for 6 hours. After the reaction was completed, the mixture was filtered while hot to recover the solid catalyst. The filtrate (acidic hydrolysate) was first distilled at atmospheric pressure to remove water, and then distilled under reduced pressure at -0.09MPa and 135℃ to collect the trimethylolpropane fraction. This fraction was dissolved in ethanol, cooled to 5℃ for crystallization for 12 hours, filtered, and the crystals were washed with cold ethanol and dried to obtain white trimethylolpropane crystals. Analysis showed that the product yield was approximately 91%, the purity was ≥99.0% (GC), and the sodium ion content was extremely low (<10 ppm).

[0057] Example 2

[0058] Take 1000g of the mother liquor of the trimethylolpropane fraction (water content 91.52%, pH=3.08), add 8g of solid superacid catalyst, and stir at 80℃ for 4 hours; the subsequent treatment is the same as in Example 1, and trimethylolpropane crystals are obtained with a yield of about 89% and a purity ≥98.8%.

[0059] Example 3

[0060] Take 500g of the concentrated trimethylolpropane fraction (acetal content 18.38%), add 15g of solid superacid catalyst, and react at 80°C for 6 hours; the subsequent treatment is the same as in Example 1, and trimethylolpropane crystals are obtained with a yield of about 84% and a purity ≥98.2%.

[0061] Comparative Example 1

[0062] Using an equivalent amount of concentrated sulfuric acid as a catalyst, after hydrolysis under the same conditions, the solution must be neutralized to pH 7 with sodium hydroxide solution, resulting in a large amount of sodium sulfate. Approximately 0.3% sodium sulfate residue was detected in the product obtained from subsequent distillation and crystallization, with a TMP purity of only about 95%, and high-salt wastewater was generated.

[0063] In summary, compared with the traditional sulfuric acid process (Comparative Example 1), this method simplifies the process and significantly improves product purity and yield without the need for a neutralization step. At the same time, it eliminates the introduction of inorganic salt impurities at the source (sodium ion content is extremely low), demonstrating the significant advantages of this method in clean production and high-quality product recovery.

[0064] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Those skilled in the art can readily implement the present invention based on the accompanying drawings and the above description. However, any modifications, alterations, or variations made by those skilled in the art without departing from the scope of the present invention, utilizing the disclosed technical content, are equivalent embodiments of the present invention. Furthermore, any modifications, alterations, or variations made to the above embodiments based on the essential technology of the present invention are still within the protection scope of the present invention.

Claims

1. A method for hydrolyzing acetal and recovering trimethylolpropane from trihydroxy compounds, comprising a recovery tank, characterized in that: The recycling tank is equipped with a filter chamber, washing pipe, rotating rod and heating pipe, and a blower pipe is suspended at the bottom of the recycling tank; It also includes the following steps: S1. Solution treatment: Mix the mother liquid with the solid catalyst and add it to the reaction vessel; S2. Heating reaction: The reaction vessel is heated and stirred to obtain a reaction solution; S3. Solid-liquid separation: Filter the solution after the reaction to remove unreacted solid catalyst; S4. Solution distillation: The acidic hydrolysate obtained above is distilled stepwise. S5. Dissolution and purification: Dissolve the trimethylolpropane main fraction obtained from distillation in an alcohol solvent, stir thoroughly, and wait for cooling and crystallization; S6. Washing and drying: The crystallized solution is filtered, washed and dried to obtain high-purity trimethylolpropane crystals.

2. The method for hydrolysis of acetal and recovery of trimethylolpropane from trihydroxy compounds according to claim 1, characterized in that: The amount of solid superacid catalyst in S1 is 5%-15% of the mass of the heavy components, and the temperature of the reaction solution during filtration in S3 is 70-80℃.

3. The method for hydrolysis of acetal and recovery of trimethylolpropane from trihydroxy compounds according to claim 1, characterized in that: The stepwise distillation in S4 includes distilling off most of the water under atmospheric pressure and distilling under reduced pressure to obtain the main fraction. The temperature is controlled at 120-150℃ and the vacuum degree is controlled at 500-1000Pa during the reduced pressure distillation.

4. The method for hydrolysis of acetal and recovery of trimethylolpropane from trihydroxy compounds according to claim 1, characterized in that: The recycling tank includes a processing compartment, with a top compartment and a bottom compartment respectively connected and assembled. A drain pipe is integrally installed at the center of the bottom of the bottom compartment, and a bracket is supported on the side of the processing compartment. Feed pipes are integrally installed on both sides of the rear end of the top compartment, and exhaust pipes are integrally installed uniformly around the top perimeter of the top compartment. The filter compartment is located at the top of the recycling tank, and the recycling tank and the filter compartment are integrally connected. The washing pipe is inserted into the rear side wall of the top compartment, and the rotating rod is suspended in the center of the top compartment. The heating pipe is inserted into the lower right side wall of the recycling tank, and the blower pipe is suspended directly below the bottom edge of the bottom compartment.

5. The method for hydrolysis of acetal and recovery of trimethylolpropane from trihydroxy compounds according to claim 4, characterized in that: The filter chamber is equipped with a receiving tray, which is inserted into the filter chamber from the left side. The outer wall of the left side of the receiving tray and the outer wall of the filter chamber are fitted with a latch. The bottom wall of the receiving tray is integrally fixed with a filter screen frame, and the center of the filter screen frame is integrally provided with a convex screen frame. The bottom of the rotating rod is equipped with a lever, and the center of the lever is convex, corresponding to the convex screen frame. The bottom shape of the lever is the same as the cross-section of the filter screen frame and the convex screen frame.

6. The method for hydrolysis of acetal and recovery of trimethylolpropane from trihydroxy compounds according to claim 4, characterized in that: The inner end of the washing pipe is integrally connected to a spray pipe, which is in a horizontal spiral shape from the outside to the inside. The center of the spray pipe is hollow and sleeved on the outside of the rotating rod. The outer side of the spray pipe is supported by an upper side support, which is fixed to the inner wall of the top chamber.

7. The method for hydrolysis of acetal and recovery of trimethylolpropane from trihydroxy compounds according to claim 4, characterized in that: The upper part of the rotating rod is fitted with a rotating sleeve, which is installed in the center of the top of the top compartment through a bearing. A worm wheel is fixed to the outside of the rotating sleeve, and a worm is meshed on the rear side of the worm wheel. A motor is connected to the side end of the worm, and a corresponding top plate is supported in the center of the top of the top compartment. The motor is supported on the surface of the top plate, and a cover is provided on the outside of the worm wheel and the worm. A pull hole is opened at the top of the rotating rod.

8. The method for hydrolysis of acetal and recovery of trimethylolpropane from trihydroxy compounds according to claim 4, characterized in that: The inner end of the heating pipe is integrally connected to an inner heating pipe, which is arranged in an S-shape and horizontally surrounds the pipe from the outside to the inside. The outer wall of the inner heating pipe is supported by a lower side support, which is supported on the lower inner wall of the processing chamber.

9. The method for hydrolysis of acetal and recovery of trimethylolpropane from trihydroxy compounds according to claim 4, characterized in that: The bottom of the compartment is recessed in an arc shape, and a blower head is integrally connected around the bottom perimeter of the compartment. A connector is integrally connected to the right side of the bottom of the blower pipe. A plug groove for connecting with the blower head is integrally connected to the top of the blower pipe. The blower head is tapered, wider at the bottom and narrower at the top, and is connected vertically. A cap is suspended and supported on the top of the blower head.

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