Novel reactor for continuously producing methyl glycolate and ethylene glycol products

Abstract

The utility model relates to the technical field of chemical engineering, in particular to a novel reactor for continuously producing methyl glycolate and ethylene glycol products, which comprises a heating furnace body, an upper group of independent reaction systems and a lower group of independent reaction systems are symmetrically arranged in the heating furnace body, and each group of reaction systems comprises a material inlet. A gas-phase material and a liquid-phase material are gasified by a preheater after entering, and then enter a first reaction tube after passing through a gas distributor, a second reaction tube is connected behind the first reaction tube, and discharge tubes are arranged between the first reaction tube and the second reaction tube and behind the second reaction tube and are connected to a condenser; liquid condensed by the condenser is collected and separated by a gas-liquid separator, and the bottom of the gas-liquid separator is connected with a product extraction pipe; a gas phase condensed by the condenser is connected to the dryer through a pipeline, and an outlet of the dryer is connected to the material inlet through a pipeline. According to the reactor provided by the utility model, through the structural design, three procedures of hydrogenation reaction, activation reaction and hydrogen recycling are integrated together, so that the production process is greatly simplified, and the production efficiency is improved.

Description

Technical Field

[0001] This utility model belongs to the field of chemical technology and relates to a process for preparing ethylene glycol by hydrogenation of oxalate esters, specifically a novel reactor for the continuous production of methyl glycolate and ethylene glycol products. Background Technology

[0002] Ethylene glycol is a colorless, odorless, high-boiling-point organic compound. Its many important properties and characteristics have led to its widespread application in numerous fields. First, ethylene glycol is an excellent solvent, capable of dissolving many organic and inorganic substances, making it an important solvent and intermediate in chemical reactions and manufacturing processes. Second, ethylene glycol possesses good wetting and stability, making it a key ingredient in many coatings, dyes, detergents, and cosmetics. Furthermore, its low volatility and high boiling point make it an ideal choice for antifreeze, heat exchange fluids, and refrigerants. Methyl glycolate is a colorless, transparent liquid with a pleasant odor. It has wide applications in various fields, such as as a high-grade cleaning solvent and chemical intermediate widely used in organic and pharmaceutical synthesis, and also in the production of polyester fibers. Industrially, ethylene glycol and methyl glycolate are generally prepared by the catalytic hydrogenation of dimethyl oxalate with hydrogen, with fixed-bed production equipment being the primary method. The literature reports (RSC Adv., 2016, 6, 111415) that the hydrogenation of dimethyl oxalate to ethylene glycol typically involves a reaction pressure of 2.2–3.0 MPa and a temperature above 200°C. Such high temperatures can easily lead to the aggregation of copper particles, causing rapid catalyst deactivation, coking, and pipe blockage, resulting in equipment shutdown and maintenance, which affects product quality and production efficiency. CN101455976A describes a dimethyl oxalate hydrogenation reaction with a reaction pressure of 3.0 MPa, a reaction temperature of 200°C, a hydrogen-to-ester mol / mol ratio of 180, and an ethylene glycol selectivity of 95%. However, such a high hydrogen-to-ester ratio places stringent requirements on the performance of the circulating compressor in the production unit, which would significantly increase production costs.

[0003] The aforementioned problems lie in the failure to adequately address heat and mass transfer of materials, separation and treatment of products in the reaction system, and recovery and utilization of raw gas during the preparation of ethylene glycol and methyl glycolate. This results in coking and the generation of reaction residues during the reaction process, leading to decreased product quality, low production efficiency, high energy consumption, and high costs. Summary of the Invention

[0004] This invention provides a novel reactor for the continuous production of methyl glycolate and ethylene glycol, solving the problems of excessive reaction residue, poor product quality, low production efficiency, high energy consumption, and high cost in the current production processes of ethylene glycol and methyl glycolate.

[0005] The technical solution of this utility model is to provide a novel reactor for the continuous production of methyl glycolate and ethylene glycol products. The reactor includes a heating furnace body with two symmetrically arranged upper and lower independent reaction systems. Each reaction system includes a material inlet, where gaseous and liquid materials enter and are vaporized by a preheater. After passing through a gas distributor, they enter a first reaction tube, which is connected to a second reaction tube. Discharge pipes are provided between the first and second reaction tubes, and also after the second reaction tube, connecting to a condenser. The condensed liquid in the condenser is collected and separated using a gas-liquid separator, with a product outlet pipe connected to the bottom of the gas-liquid separator. The condensed gas phase is connected to a dryer via a pipeline, and the dryer outlet is connected to the material inlet via a pipeline.

[0006] Furthermore, the preheater adopts a jacketed heat exchanger, an immersed coil heat exchanger, a shell-and-tube heat exchanger, or a P-type heat exchanger.

[0007] Furthermore, the gas distributor is a dual-tangential circulating gas distributor, an annular gas distributor, or a flat plate gas distributor.

[0008] Furthermore, the first and second reaction tubes are filled with catalyst.

[0009] Furthermore, the condenser is a two-stage condenser, specifically a primary condenser and a secondary condenser, which are connected in series. The liquid condensed by the primary condenser and the secondary condenser are both connected to the gas-liquid separator through pipelines.

[0010] Furthermore, U-shaped bends are provided on the pipes of the primary condenser and the secondary condenser condenser and the gas-liquid separator.

[0011] Furthermore, the dryer includes a hydrogen filter and a drying tube.

[0012] Furthermore, the hydrogen filter is a carbon steel cylindrical hydrogen filter, a carbon steel T-type hydrogen filter, or a stainless steel T-type hydrogen filter; the drying tube is filled with a drying medium.

[0013] This utility model has the following beneficial effects:

[0014] The reactor provided by this invention, by setting up two independent reaction systems within the reactor, can produce simultaneously or have one system in standby mode. Especially when the catalyst is deactivated and requires regeneration, one reaction system operates normally while the other is purged with hydrogen to regenerate the catalyst. This structural design integrates the hydrogenation reaction, activation reaction, and hydrogen recycling processes, greatly simplifying the production process and improving efficiency. Furthermore, the hydrogen tail gas after the reaction can be directly recycled, not only improving raw material utilization but also reusing the heat generated by the hydrogen tail gas, saving energy and reducing production costs. Different catalysts can be loaded into the reaction tubes, making the post-reaction products controllable and facilitating product quality control. Simultaneously, the reaction and regeneration tubes can operate simultaneously and be switched at any time, greatly reducing coking and improving product quality. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the structure of this utility model. Detailed Implementation

[0016] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings. However, those skilled in the art will understand that the following embodiments are only used to illustrate the present invention and should not be regarded as limiting the scope of the present invention.

[0017] like Figure 1 As shown, this utility model provides a novel reactor for the continuous production of methyl glycol and ethylene glycol products. It includes a heating furnace body 1, within which two independent reaction systems are symmetrically arranged, upper and lower. Each reaction system includes a material inlet 1-1, where gaseous and liquid materials enter and are vaporized via a preheater 1-2. After passing through a gas distributor 1-3, they enter a first reaction tube 1-4, which is connected to a second reaction tube 1-5. Discharge pipes are provided between the first and second reaction tubes, and after the second reaction tube, connecting to a condenser 2. The condensed liquid in the condenser is collected and separated using a gas-liquid separator 3, with a product outlet pipe connected to the bottom of the gas-liquid separator. The condensed gas phase is connected to a dryer 4 via a pipeline, and the dryer outlet is connected to the material inlet via a pipeline. The dryer outlet is also connected to a tail gas outlet pipeline to regulate the system's hydrogen pressure and quality; substandard hydrogen is discharged from the system from this outlet. The pipeline between the dryer outlet and the material inlet is used for hydrogen reuse, and a hydrogen replenishment pipeline can also be installed as needed.

[0018] The heating furnace body can be made of Hastelloy, a material that is resistant to high temperatures, has fast heat transfer, is resistant to acid corrosion, and provides excellent protection against solvents and hydrogen present in the production process.

[0019] In some embodiments, the preheater is a jacketed heat exchanger, an immersed coil heat exchanger, a shell-and-tube heat exchanger, or a P-type heat exchanger. The heat exchanger can rapidly heat and raise the temperature of hydrogen and liquid feedstock, allowing the feedstock to be vaporized as much as possible before entering the catalyst bed in the reaction tube for reaction.

[0020] In some embodiments, the gas distributor is a dual-tangential circulating gas distributor, an annular gas distributor, or a flat-plate gas distributor. The gas distributor thoroughly mixes the gaseous feedstock heated and vaporized in the preheater and then uniformly flows it into the catalyst bed in the reaction tube. This ensures more complete contact between hydrogen, dimethyl oxalate, and the catalyst, thereby increasing the degree of dimethyl oxalate hydrogenation.

[0021] In some embodiments, the first and second reaction tubes are filled with a catalyst. Both reaction tubes are made of Hastelloy alloy, which is resistant to high temperatures, alcohol solvent corrosion, and hydrogen erosion. The high material strength also prevents breakage and leakage, facilitating temperature control. The first and second reaction tubes can contain the same or different catalysts, and the catalyst loading can be adjusted according to reaction requirements. The mixture from the first and second reaction tubes then enters a condenser for condensation.

[0022] In some embodiments, the condenser is a two-stage system, specifically a primary condenser 2-1 and a secondary condenser 2-2, connected in series. The liquids condensed by both the primary and secondary condensers are connected to a gas-liquid separator via pipelines. Both the primary and secondary condensers use titanium tube condensers, which are corrosion-resistant, pressure-resistant, high-strength, and have a fast heat exchange rate. The cooling medium of the primary condenser is a frozen sodium chloride brine, with the temperature controlled between -3 and 3°C. This cooling temperature ensures that moisture and high-boiling-point products in the reaction gas are condensed into liquid, thus preventing dimethyl oxalate from condensing and clogging pipelines and equipment. The cooling medium of the secondary condenser is a low-temperature cryogenic liquid, which is a 35% ethylene glycol-sodium chloride brine mixture with a temperature controlled between -15 and -8°C. This mixture has a good cooling effect and can completely condense the large amount of solvent and low-boiling-point intermediate products present in the reaction gas, reducing system material loss. The temperature of the frozen sodium chloride brine in the primary condenser shall not exceed 0°C, and the temperature of the 35% ethylene glycol-sodium chloride brine mixture in the secondary condenser shall be controlled below -10°C.

[0023] In some embodiments, the pipes of the primary condenser and the secondary condenser condenser and the gas-liquid separator are provided with U-bends to prevent hydrogen from crossing.

[0024] In some embodiments, the dryer 4 includes a hydrogen filter 4-1 and a drying tube 4-2. The filter is a stainless steel T-type hydrogen filter, which is corrosion-resistant and high-temperature resistant, and can filter out tiny particles with a diameter of 40μm or larger in the hydrogen exhaust gas, thus avoiding affecting the quality of recycled hydrogen. The drying tube is made of stainless steel, and the drying medium inside the drying tube is a solid adsorbent with strong water absorption, solvent resistance, and stable properties. This solid adsorbent can be silica gel, alumina, zeolite molecular sieve, kaolin, etc. Kaolin is preferred because it has strong water absorption, large water absorption capacity, long service life, and low cost.

[0025] In some embodiments, the hydrogen filter is a carbon steel cylindrical hydrogen filter, a carbon steel T-type hydrogen filter, or a stainless steel T-type hydrogen filter; the drying tube is filled with a drying medium.

[0026] In actual production, after the catalyst is loaded into the reaction tube, the gas inlet valve is opened, and the system is first purged with nitrogen. After purging, hydrogen is switched on for further purging. After purging, hydrogen is continuously supplied, while the system pressure is controlled at 2.1 MPa and the hydrogen flow rate is controlled at 50 L / h. Then, the heating switch of the furnace body is turned on to start heating, and the heating rate is controlled at 5℃ / min. When the catalyst bed temperature in the reaction tube reaches 250℃, activation begins and is maintained at this temperature for 4.5 hours. After activation, the temperature is lowered to 185℃, and after the temperature stabilizes, adjustments are made. The hydrogen flow rate was increased to 180 L / h, and the liquid feed pump was turned on to pump a 50% dimethyl oxalate methanol solution into the reaction tube at a feed rate of 1.3 t / h. After 3.5 h of reaction, the product began to exit from the bottom of the gas-liquid separator. Sampling and analysis showed that the methyl glycolate content was 96.2% and the ethylene glycol content was 3.0%. After loading different types of catalysts, the methyl glycolate content in the product was 1.5% and the ethylene glycol content was 98.0%. The product quality met the requirements. The product was discharged and packaged through the product collection pipe.

[0027] The above embodiments describe preferred embodiments of the present invention, but the present invention is not limited thereto. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, including combining the various technical features in any other way. These simple modifications and combinations should also be considered as the content disclosed by the present invention and all fall within the protection scope of the present invention. Therefore, the protection scope of the present invention patent should be determined by the appended claims.

Claims

1. A novel reactor for the continuous production of methyl glycolate and ethylene glycol, characterized in that: The system includes a heating furnace body, within which two independent upper and lower reaction systems are symmetrically arranged. Each reaction system includes a material inlet, where gaseous and liquid materials enter and are vaporized by a preheater. After passing through a gas distributor, they enter the first reaction tube, which is connected to the second reaction tube. Discharge pipes are provided between the first and second reaction tubes and after the second reaction tube, connecting to a condenser. The liquid condensed by the condenser is collected and separated using a gas-liquid separator, with a product outlet pipe connected to the bottom of the gas-liquid separator. The gas phase condensed by the condenser is connected to a dryer via a pipeline, and the dryer outlet is connected to the material inlet via a pipeline.

2. The novel reactor for the continuous production of methyl glycolate and ethylene glycol products according to claim 1, characterized in that: The preheater is a jacketed heat exchanger, an immersed coil heat exchanger, a shell-and-tube heat exchanger, or a P-type heat exchanger.

3. The novel reactor for the continuous production of methyl glycolate and ethylene glycol products according to claim 1, characterized in that: The gas distributor is a dual-tangential circulating gas distributor, an annular gas distributor, or a flat gas distributor.

4. The novel reactor for the continuous production of methyl glycolate and ethylene glycol products according to claim 1, characterized in that: The first and second reaction tubes are filled with catalyst.

5. The novel reactor for the continuous production of methyl glycolate and ethylene glycol products according to any one of claims 1 to 4, characterized in that: The condenser is a two-stage condenser, specifically a primary condenser and a secondary condenser, which are connected in series. The liquid condensed by the primary and secondary condensers is connected to the gas-liquid separator through pipelines.

6. The novel reactor for continuous production of methyl glycolate and ethylene glycol products as claimed in claim 5 wherein: The pipes of the primary condenser and the secondary condenser condenser and the gas-liquid separator are equipped with U-shaped bends.

7. The novel reactor for continuous production of methyl glycolate and ethylene glycol products as claimed in claim 5 wherein: The dryer includes a hydrogen filter and a drying tube.

8. The novel reactor for the continuous production of methyl glycolate and ethylene glycol products according to claim 7, characterized in that: The hydrogen filter is a carbon steel cylindrical hydrogen filter, a carbon steel T-type hydrogen filter, or a stainless steel T-type hydrogen filter; the drying tube is filled with a drying medium.

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