A methanol production system based on catalytic hydrogenolysis of waste liquid from ethylene glycol production

Abstract

This utility model relates to the fields of environmental protection and comprehensive resource utilization technology, and in particular to a methanol production system based on the catalytic hydrogenolysis of waste liquid from ethylene glycol production. The system includes a vaporization device, a catalytic hydrogenolysis reactor, a heat exchanger, a gas-liquid separator, a product storage tank, a compressor, and a buffer tank. The compressor outlet is connected to the gas inlet of the vaporization device, and the vaporization device outlet is connected to the inlet of the catalytic hydrogenolysis reactor. The outlet of the catalytic hydrogenolysis reactor is sequentially connected to the material inlets of the heat exchanger and the gas-liquid separator. The top gas phase outlet of the gas-liquid separator is connected to the inlet of the buffer tank, and the outlet of the buffer tank is connected to the inlet of the compressor. The bottom liquid phase outlet of the gas-liquid separator is connected to the inlet of the product storage tank. This utility model provides a methanol production system based on the catalytic hydrogenolysis of waste liquid from ethylene glycol production, solving the technical problem that waste liquid is usually treated as hazardous waste, and enterprises use direct incineration, resulting in resource waste and environmental pollution.

Description

Technical Field

[0001] This utility model relates to the field of industrial environmental protection and comprehensive resource utilization technology, and in particular to a methanol production system based on the catalytic hydrogenolysis of waste liquid in ethylene glycol production. Background Technology

[0002] In the industrial production of ethylene glycol from syngas, poor catalyst selectivity generates a mixed waste liquid containing methyl formate, methyl acetal, methanol, and dimethyl carbonate. In this waste liquid, methyl formate and methyl acetal readily form azeotropes with methanol, making efficient separation difficult with traditional distillation techniques, resulting in high costs and low efficiency. Furthermore, methyl formate and methyl acetal have low boiling points, making them difficult to store and transport, further increasing the difficulty of recycling.

[0003] Currently, most companies use direct incineration to treat this waste liquid, which wastes usable resources such as methanol, may cause environmental pollution, and also requires them to bear the operation and maintenance costs of the incineration equipment, putting both economic and environmental pressures on the companies.

[0004] Among the existing related patented technologies, some separate methyl formate from waste liquid through recycling and refining methods. However, because methyl formate accounts for less than 2% of the waste liquid and has a complex composition, the equipment investment is large, the process is complicated, and the cost is high, thus preventing industrial application. Other patents use high-pressure hydrogenation of pure methyl formate or distillation to concentrate before hydrogenation to produce methanol. The former requires purification of methyl formate, which is a long process, costly, and prone to producing byproducts. The latter still contains unconverted methyl formate and untreated methylal after hydrogenation, which accumulate in the system and require regular discharge of waste liquid. Similarly, these technologies have not been industrialized and cannot fundamentally solve the waste liquid treatment problem. Utility Model Content

[0005] In view of this, the present invention provides a methanol production system based on the catalytic hydrogenolysis of waste liquid in ethylene glycol production, aiming to solve the above-mentioned technical problems.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A methanol production system based on catalytic hydrogenolysis of waste liquid from ethylene glycol production includes a vaporization device, a catalytic hydrogenolysis reactor, a heat exchanger, a gas-liquid separator, a product storage tank, a compressor, and a buffer tank. The outlet of the compressor is connected to the gas inlet of the vaporization device, and the outlet of the vaporization device is connected to the inlet of the catalytic hydrogenolysis reactor. The outlet of the catalytic hydrogenolysis reactor is connected in sequence to the material inlets of the heat exchanger and the gas-liquid separator. The top gas phase outlet of the gas-liquid separator is connected to the inlet of the buffer tank, and the outlet of the buffer tank is connected to the inlet of the compressor. The bottom liquid phase outlet of the gas-liquid separator is connected to the inlet of the product storage tank.

[0008] Preferably, the catalytic hydrogenolysis reactor includes a shell, and an insulation layer is provided in the inner wall of the shell, the insulation layer covering the entire area of ​​the inner wall of the shell.

[0009] Preferably, a thermometer is installed through the shell sidewall of the catalytic hydrogenolysis reactor. The detection end of the thermometer passes through the insulation layer and extends into the inner cavity of the shell, while the display end of the thermometer is located on the outer side of the shell. A high-temperature air inlet is provided on the upper sidewall of the shell. One end of the high-temperature air inlet is connected to the inner cavity of the shell, and the other end extends to the outer side of the shell and is used to connect to a high-temperature air delivery pipeline.

[0010] Preferably, a gas distributor is fixedly installed in the inner cavity of the shell of the catalytic hydrogenolysis reactor. The gas distributor is located below the high-temperature air inlet, and the edge of the gas distributor is tightly fitted to the inner wall of the shell. A guide plate is arranged parallel to the gas distributor, and the guide plate is uniformly inclined at an angle to form guide holes.

[0011] Preferably, at least one heat exchange tube is also provided in the inner cavity of the shell, and a reaction layer is provided inside the heat exchange tube.

[0012] Preferably, the bottom side wall of the catalytic hydrogenolysis reactor shell is provided with a drain hole, which is connected to the bottom area of ​​the shell cavity, and a sealing valve for controlling the on / off state is installed on the drain hole; an exhaust hole is provided at the bottom center of the shell, which is connected to the shell cavity, and a pressure relief valve is installed on the exhaust hole.

[0013] Preferably, the pressure relief valve is installed inside the vent hole, an elastic component is provided between the pressure relief valve and the vent hole, and a pressure relief hole is provided on the vent hole.

[0014] Compared with existing technologies, a methanol production system based on catalytic hydrogenolysis of waste liquid from ethylene glycol production has the following advantages:

[0015] The system utilizes a continuous structure of "catalytic hydrogenolysis reactor-heat exchanger-gas-liquid separator" to directly vaporize mixed waste liquid containing methyl formate, methyl acetal, dimethyl carbonate, and methanol before feeding it into the catalytic hydrogenolysis reactor. This eliminates the need for pre-treatment through complex processes such as distillation to separate the components in the waste liquid. The system avoids the multi-step purification steps for azeotropic compounds found in traditional separation technologies, and circumvents the high cost and low efficiency of traditional distillation, achieving direct conversion and treatment of waste liquid.

[0016] The catalytic hydrogenolysis reactor, through its internal insulation layer, heat exchange tubes, and gas distributor, provides a stable reaction environment for the hydrogenolysis of components such as methyl formate and methyl acetal in the waste liquid. This ensures that the difficult-to-separate components are efficiently converted into methanol, rather than being separated and purified separately, thus fundamentally solving the problem of azeotropic separation.

[0017] The structural design of the hydrogenolysis reactor, including the drain hole (for easy cleaning of impurities), pressure relief valve (to ensure stable pressure), and thermometer (for real-time monitoring of reaction temperature), ensures long-term stable operation of the system. At the same time, the cooperation between the gas-liquid separator, buffer tank, and compressor enables hydrogen recycling, reduces hydrogen consumption, and improves system operational stability and resource utilization. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of this utility model 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 embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0019] Figure 1 This is a system schematic diagram of the present invention;

[0020] Figure 2 This is a schematic diagram of the catalytic hydrogenolysis reactor structure of this utility model;

[0021] Figure 3 This is an enlarged view of the structure of the present invention.

[0022] Reference numerals: 1. Vaporization device; 2. Catalytic hydrogenolysis reactor; 3. Heat exchanger; 4. Gas-liquid separator; 5. Product storage tank; 6. Compressor; 7. Shell; 8. Thermometer; 9. High-temperature air inlet; 10. Gas distributor; 11. Drain hole; 12. Exhaust hole; 13. Pressure relief valve; 14. Pressure relief hole; 15. Elastic component; 16. Baffle plate; 17. Reaction layer; 18. Heat exchange tube. Detailed Implementation

[0023] The technical solutions in the embodiments of this utility model are described clearly and completely below. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. 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.

[0024] Example 1

[0025] like Figure 1-3 As shown, a methanol production system based on catalytic hydrogenolysis of waste liquid from ethylene glycol production is presented in this embodiment. The core of this system is used to treat the mixed waste liquid containing methyl formate, methyl acetal, methanol, and dimethyl carbonate generated during the ethylene glycol production process from syngas. The overall structure and working principle of the system are as follows:

[0026] The system includes a vaporization unit 1, a catalytic hydrogenolysis reactor 2, a heat exchanger 3, a gas-liquid separator 4, a product storage tank 5, a compressor 6, and a buffer tank. All equipment is connected in a sealed manner via corrosion-resistant stainless steel pipelines. Specifically, the outlet of the compressor 6 is connected to the gas inlet of the vaporization unit 1 to pressurize and transport hydrogen to the vaporization unit 1; the outlet of the vaporization unit 1 is connected to the inlet of the catalytic hydrogenolysis reactor 2 to stably feed the vaporized gas-liquid mixture into the reactor; the outlet of the catalytic hydrogenolysis reactor 2 is connected to the material inlets of the heat exchanger 3 and the gas-liquid separator 4 via pipelines, allowing the reaction products to undergo heat exchange in the heat exchanger 3 before entering the gas-liquid separator 4 for component separation; the top gas phase outlet of the gas-liquid separator 4 is connected to the inlet of the buffer tank, and the outlet of the buffer tank is connected to the inlet of the compressor 6, forming a hydrogen circulation channel; the bottom liquid phase outlet of the gas-liquid separator 4 is connected to the inlet of the product storage tank 5 to collect the methanol product generated during the conversion.

[0027] In actual operation, the waste liquid from the methanol distillation system of the syngas to ethylene glycol unit is transported to the liquid inlet of the vaporization unit 1 by the feed pump. At the same time, the compressor 6 pressurizes the hydrogen and sends it to the gas inlet of the vaporization unit 1. The waste liquid is fully mixed with the hydrogen in the vaporization unit 1 and vaporization is completed. This process does not require the separation of azeotropic substances by distillation first, which directly eliminates the multi-step purification process in traditional technology. It effectively avoids the defects of high cost and low efficiency of traditional distillation and reduces equipment investment and operating energy consumption.

[0028] The vaporized gas-liquid mixture enters the catalytic hydrogenolysis reactor 2. Under the action of the hydrogenation catalyst in the reactor, components such as methyl formate, methyl acetal, and dimethyl carbonate undergo hydrogenolysis to produce methanol. The reaction products first enter the heat exchanger 3, transferring their own heat to the subsequent heating medium (such as unvaporized waste liquid), realizing system heat recovery and utilization, and reducing overall energy consumption. Subsequently, the products enter the gas-liquid separator 4. The gas phase (mainly unreacted hydrogen) is discharged from the top into the buffer tank. After buffering and stabilization, it returns to the compressor 6 for repressurization, realizing hydrogen recycling, reducing hydrogen consumption, and improving resource utilization. The liquid phase (mainly the generated methanol) is discharged from the bottom into the product storage tank 5. After testing, the methanol mass fraction in the liquid phase is greater than 90%, which can be directly reused in the methyl nitrite regeneration tower, nitric acid reduction tower, and other sections of the ethylene glycol production system, realizing the resource utilization of waste liquid, replacing the traditional incineration treatment method, avoiding methanol resource waste, reducing environmental pollution caused by incineration, and alleviating the dual economic and environmental pressures on enterprises.

[0029] Example 2

[0030] This embodiment provides a catalytic hydrogenolysis reactor 2 adapted to the system of Embodiment 1. The catalytic hydrogenolysis reactor 2 includes a cylindrical shell 7. An insulation layer is attached to the inner wall of the shell 7. The insulation layer is made of high-temperature resistant ceramic fiber material and completely covers the entire area of ​​the inner wall of the shell 7. The insulation layer can effectively reduce the loss of reaction heat in the reactor, maintain the temperature stability of the reaction area, provide a constant temperature environment for the hydrogenolysis reaction, avoid the decrease in reaction efficiency or the increase of by-products due to temperature fluctuations, and ensure the methanol conversion efficiency.

[0031] A thermometer 8 is installed through the side wall of the shell 7. The thermometer 8 is a high-temperature platinum resistance thermometer. Its detection end passes through the insulation layer and extends into the reaction area inside the shell 7. The display end is located on the outside of the shell 7 and connected to the control system. The operator can monitor the temperature of the reaction area in real time through the thermometer 8. When the temperature deviates from the set range (120~350℃), the heating parameters can be adjusted in time to ensure that the reaction is always carried out under the optimal temperature conditions, further improving the reaction stability and methanol selectivity. A high-temperature air inlet 9 is also opened on the upper side wall of the shell 7. One end of the inlet is connected to the inner cavity of the shell 7, and the other end extends to the outside of the shell 7 and is connected to the high-temperature air supply pipeline through a flange. When rapid heating is required in the early stage of the reaction, or when the temperature drops slightly during the reaction, high-temperature air can be introduced into the shell 7 through the high-temperature air inlet 9 to quickly replenish the heat, ensure the stability of the reaction temperature, and avoid the reaction start-up delay caused by slow heating.

[0032] A gas distributor 10 is fixedly installed in the lower part of the inner cavity of the shell 7. The gas distributor 10 is made of porous stainless steel plate and is located directly below the high-temperature air inlet 9. Its edges are tightly fitted to the inner wall of the shell 7 and the insulation layer. After the gas-liquid mixture (containing waste liquid vapor and hydrogen) sent from the vaporization device 1 enters the inner cavity of the shell 7, it first passes through the gas distributor 10. The uniform channels on the distributor can disperse the gas-liquid mixture into fine airflows, so that hydrogen and waste liquid vapor are fully mixed, avoiding excessively high or low local reactant concentrations, and improving the reaction efficiency. Uniformity is required; a guide plate 16 is arranged parallel above the gas distributor 10. The guide plate 16 is welded and fixed to the inner wall of the shell 7 and the insulation layer. The guide plate 16 is evenly provided with guide holes at an inclined angle. When the gas-liquid mixture dispersed by the gas distributor 10 flows upward, the inclined guide holes of the guide plate 16 can guide the airflow to flow in a specific direction, avoid the airflow directly impacting the reaction layer 17 below, and at the same time prolong the residence time of the gas-liquid mixture in the shell 7, so that the reactants and catalyst can fully contact each other and improve the reaction efficiency.

[0033] Several heat exchange tubes 18 are installed inside the shell 7. The heat exchange tubes 18 are made of high-temperature resistant alloy steel pipes and are evenly arranged along the length of the shell 7, penetrating the reaction layer 17 in the middle of the shell 7. The two ends of the heat exchange tubes 18 protrude from the two side walls of the shell 7, and both ends are connected to the heating medium delivery pipeline through flanges. The reaction layer 17 is filled with a catalyst. When the gas-liquid mixture flows through the reaction layer 17, a hydrogenolysis reaction occurs under the action of the catalyst. At the same time, the heating medium (such as high-temperature steam) flows in the heat exchange tubes 18 and transfers heat to the reaction layer 17 through the tube walls, ensuring that the heat required for the reaction is sufficient and maintaining the reaction temperature stable within the optimal range. The uniform arrangement of the heat exchange tubes 18 can make the reaction layer 17 heated evenly, avoiding local overheating that could lead to catalyst deactivation. In addition, this multi-row tube heat exchange structure can flexibly adjust the flow rate of the heating medium to adapt to the reaction heat requirements under different waste liquid compositions, thereby improving the applicability of the reactor.

[0034] A drain hole 11 is provided on the bottom side wall of the shell 7, which communicates with the bottom area of ​​the inner cavity of the shell 7. A sealing valve (using a high-temperature resistant shut-off valve) for controlling the on / off state is installed on the drain hole 11. During the reaction, a small amount of solid impurities (catalyst wear particles) may be generated. These impurities will deposit at the bottom of the inner cavity of the shell 7. By periodically opening the sealing valve, the impurities can be discharged through the drain hole 11 to prevent the accumulation of impurities from affecting the flow of the gas-liquid mixture or contaminating the catalyst, thus ensuring the long-term stable operation of the reactor. An exhaust hole 12 is provided at the bottom center of the shell 7, which communicates with the inner cavity of the shell 7. A pressure relief valve 13 is installed on the exhaust hole 12, which is installed inside the exhaust hole 12. A spring (elastic component 15) is installed between the pressure relief valve 13 and the wall of the exhaust port 12. The side wall of the exhaust port 12 is also provided with a pressure relief hole 14. When the pressure inside the shell 7 exceeds the set value due to reaction fluctuations, the high-pressure gas in the cavity pushes the pressure relief valve 13 to compress the spring, so that a gap is formed between the pressure relief valve 13 and the wall of the exhaust port 12. The high-pressure gas enters the pressure relief hole 14 through the gap and is discharged from the shell 7 until the pressure inside the cavity drops to a safe range. The spring pushes the pressure relief valve 13 to reset and close. This pressure relief structure can effectively prevent the equipment from being damaged or having a safety accident due to excessive pressure inside the reactor, and ensure the safety of reactor operation. At the same time, the setting of the elastic component 15 enables the pressure relief valve 13 to have an automatic reset function, which does not require manual operation and improves the convenience of equipment operation and maintenance.

[0035] Through the above structural design, the catalytic hydrogenolysis reactor 2 can achieve uniform dispersion of gas-liquid mixture, stable control of reaction temperature, and safe adjustment of reaction pressure, ensuring that difficult-to-separate components such as methyl formate, methyl acetal, and dimethyl carbonate in the waste liquid are efficiently converted into methanol. It can also simultaneously treat multiple impurity components, avoiding the accumulation of untreated impurities in the system. This solves the problem of impurity accumulation after hydrogenation in existing technologies, which requires periodic discharge of waste liquid, further improving the overall treatment effect of the system and the feasibility of industrial application.

[0036] Although embodiments of this application have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of this application, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A methanol production system based on catalytic hydrogenolysis of waste liquid from ethylene glycol production, characterized in that, The system includes a vaporization device (1), a catalytic hydrogenolysis reactor (2), a heat exchanger (3), a gas-liquid separator (4), a product storage tank (5), a compressor (6), and a buffer tank. The outlet of the compressor (6) is connected to the gas inlet of the vaporization device (1), and the outlet of the vaporization device (1) is connected to the inlet of the catalytic hydrogenolysis reactor (2). The outlet of the catalytic hydrogenolysis reactor (2) is connected in sequence to the material inlets of the heat exchanger (3) and the gas-liquid separator (4). The top gas phase outlet of the gas-liquid separator (4) is connected to the inlet of the buffer tank, and the outlet of the buffer tank is connected to the inlet of the compressor (6). The bottom liquid phase outlet of the gas-liquid separator (4) is connected to the inlet of the product storage tank (5).

2. The methanol production system based on catalytic hydrogenolysis of waste liquid in ethylene glycol production according to claim 1, characterized in that, The catalytic hydrogenolysis reactor (2) includes a shell (7), and an insulation layer is provided in the inner wall of the shell (7), covering the entire area of ​​the inner wall of the shell (7).

3. The methanol production system based on catalytic hydrogenolysis of waste liquid in ethylene glycol production according to claim 2, characterized in that, A thermometer (8) is installed through the side wall of the shell (7) of the catalytic hydrogenolysis reactor (2). The detection end of the thermometer (8) passes through the insulation layer and extends into the inner cavity of the shell (7). The display end of the thermometer (8) is located outside the shell (7). A high-temperature air inlet (9) is provided on the upper side wall of the shell (7). One end of the high-temperature air inlet (9) is connected to the inner cavity of the shell (7), and the other end extends to the outside of the shell (7) and is used to connect to the high-temperature air delivery pipeline.

4. A methanol production system based on catalytic hydrogenolysis of waste liquid in ethylene glycol production according to claim 2, characterized in that, A gas distributor (10) is fixedly installed in the inner cavity of the shell (7) of the catalytic hydrogenolysis reactor (2). The gas distributor (10) is located below the high-temperature air inlet (9), and the edge of the gas distributor (10) is tightly attached to the inner wall of the shell (7). A guide plate (16) is arranged parallel to the gas distributor (10), and the guide plate (16) is uniformly inclined and forms guide holes.

5. A methanol production system based on catalytic hydrogenolysis of waste liquid in ethylene glycol production according to claim 4, characterized in that, At least one heat exchange tube (18) is also provided in the inner cavity of the shell (7), and a reaction layer (17) is provided inside the heat exchange tube (18).

6. A methanol production system based on catalytic hydrogenolysis of waste liquid in ethylene glycol production according to claim 2, characterized in that, The bottom side wall of the shell (7) of the catalytic hydrogenolysis reactor (2) is provided with a drain hole (11), which is connected to the bottom area of ​​the inner cavity of the shell (7), and a sealing valve for controlling the opening and closing is installed on the drain hole (11); an exhaust hole (12) is provided at the center of the lower part of the shell (7), which is connected to the inner cavity of the shell (7), and a pressure relief valve (13) is installed on the exhaust hole (12).

7. A methanol production system based on catalytic hydrogenolysis of waste liquid in ethylene glycol production according to claim 6, characterized in that, The pressure relief valve (13) is installed inside the vent (12), and an elastic component (15) is provided between the pressure relief valve (13) and the vent (12). The vent (12) is provided with a pressure relief hole (14).

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