Method and system for increasing yield of diethylene glycol and triethylene glycol

Abstract

The invention belongs to the field of diethylene glycol production, and relates to a method and a system for increasing the yield of diethylene glycol (DEG) and triethylene glycol (TEG) by using an EOEG device. The method for increasing the yield of diethylene glycol and triethylene glycol comprises the steps that monoethylene glycol, ethylene oxide and optional diethylene glycol are subjected to an N-stage reaction in the presence of a catalyst, N is an integer not smaller than 2, a reaction solution obtained in the previous stage is subjected to interstage heat removal, ethylene oxide is supplemented, and then the reaction solution enters the next stage for reaction, a reaction solution containing monoethylene glycol, diethylene glycol, triethylene glycol and heavy alcohol is obtained after the N-stage reaction, and then monoethylene glycol, diethylene glycol, triethylene glycol and heavy alcohol are obtained through separation. According to the invention, a multi-stage reactor (preferably a multi-stage tubular reactor) is adopted, and a method of inter-stage heat removal and segmented ethylene oxide supplementation is combined, so that under the condition of ensuring safety, the supplementation amount of ethylene oxide can reach 45% (based on the total amount of raw materials except ethylene oxide being 100%), the yield of diethylene glycol and triethylene glycol is increased to the maximum extent, and the yield of ethylene glycol and triethylene glycol is increased to the maximum extent. The conversion per pass of monoethylene glycol is high, and the subsequent separation energy consumption is low. Meanwhile, a product scheme can be adjusted, and subsequently rectified diethylene glycol is returned to a reaction system, so that the yield of triethylene glycol is further increased.

Description

Technical Field

[0001] This invention belongs to the field of diethylene glycol production, and relates to a method and system for increasing the production of diethylene glycol (DEG) and triethylene glycol (TEG) in an EOEG unit. Background Technology

[0002] Diethylene glycol (DEG) can be used to produce unsaturated resins and plasticizers. It is also used in antifreeze agents, gas dehydrating agents, etc.

[0003] Triethylene glycol (TEG) can be used as a solvent for aromatic hydrocarbon extraction, a solvent for rubber and nitrocellulose, and as an additive for diesel fuel and rocket fuel. It also has wide applications in the pharmaceutical, coating, textile, printing and dyeing, food, papermaking, cosmetics, leather, photography, printing, and metal processing industries. It is commonly used as a textile auxiliary agent, solvent, plasticizer for rubber and resins, viscosity modifier for lubricating oils, and aromatic hydrocarbon extractant for reforming fluids.

[0004] With the development of fine chemicals, the market for diethylene glycol and triethylene glycol has gradually improved. At a certain stage, their prices were higher than those of ethylene oxide. Utilizing ethylene oxide and ethylene glycol to increase the production of diethylene glycol and triethylene glycol can bring significant economic benefits to enterprises.

[0005] In this invention, the reaction is a strongly exothermic reaction. For safety reasons, the temperature of the reaction system needs to be controlled within 230°C. Otherwise, if the temperature is too high, the entire system's pressure will reach 600 pounds, increasing investment and potentially causing the medium inside the reactor to vaporize, leading to safety issues. Furthermore, increasing the concentration of EO will increase the adiabatic temperature rise of the reaction. Therefore, the concentration of EO (ethylene oxide) in the hydrated reactor needs to be strictly controlled; otherwise, the temperature of the reaction system will exceed the safe range.

[0006] Traditional technology recycles ethylene glycol to the hydration reactor, which can partially increase the production of diethylene glycol and triethylene glycol. However, the subsequent multi-effect evaporation section, vacuum drying tower, and MEG tower consume a large amount of steam, resulting in high energy consumption and uneconomical production. Furthermore, the need for strict control of EO concentration in the hydration reactor leads to low selectivity for diethylene glycol and triethylene glycol, resulting in minimal production increases. Therefore, this method is uneconomical.

[0007] This invention employs a multi-stage tubular reactor with staged injection of ethylene oxide, combined with an interstage heat removal scheme, to maximize the conversion of monoethylene glycol (ethylene glycol) in the reactor into diethylene glycol and triethylene glycol. The reactor outlet exhibits high concentrations of diethylene glycol and triethylene glycol, which not only maximizes the yield of these two alcohols but also results in an anhydrous reaction system and low energy consumption in the subsequent distillation stage. The overall process is simplified and has low operating costs. Summary of the Invention

[0008] The technical problem this invention aims to solve is that existing technologies for increasing the production of diethylene glycol and triethylene glycol suffer from drawbacks such as low diethylene glycol and triethylene glycol yields, high monoethylene glycol concentration at the reactor outlet, and high energy consumption for subsequent separation of unreacted monoethylene glycol. This invention provides a method and system for increasing the production of diethylene glycol and triethylene glycol. It employs a multi-stage reactor (preferably a multi-stage tubular reactor) combined with interstage deheating and staged ethylene oxide replenishment. Under safe conditions, the ethylene oxide replenishment can reach 45% (based on a 100% total amount of raw materials excluding ethylene oxide), maximizing the production of diethylene glycol and triethylene glycol, achieving a high single-pass conversion rate for monoethylene glycol, and low energy consumption for subsequent separation. Furthermore, the product scheme can be adjusted to return diethylene glycol from subsequent distillation to the reaction system, further increasing triethylene glycol production.

[0009] The first aspect of the present invention is to provide a method for increasing the production of diethylene glycol and triethylene glycol, comprising carrying out an N-stage reaction of monoethylene glycol, ethylene oxide, and optionally diethylene glycol in the presence of a catalyst, wherein N is an integer not less than 2, subjecting the reaction solution obtained from the previous stage to interstage deheating and adding ethylene oxide before proceeding to the next stage reaction, and obtaining a reaction solution containing monoethylene glycol, diethylene glycol, triethylene glycol, and heavy alcohol after the N-stage reaction, and then obtaining monoethylene glycol, diethylene glycol, triethylene glycol, and heavy alcohol by separation.

[0010] According to the present invention, N is an integer not less than 2, for example, it can be 2, 3, 4, 5..., preferably 2-3 levels, and more preferably 3 levels.

[0011] According to the present invention, the more ethylene oxide is added, the more diethylene glycol and triethylene glycol are produced. However, a large amount of ethylene oxide will increase the adiabatic temperature rise of the reactor, and the reactor outlet temperature cannot be too high. According to some preferred embodiments of the present invention, the content of ethylene oxide in the feed material of each stage of the reaction is no more than 15 wt%, for example, it can be 7-15 wt%. Under this preferred condition, the yield of diethylene glycol and triethylene glycol is increased, and at the same time, the adiabatic temperature rise of the reactor can be controlled within a preferred range.

[0012] According to the present invention, the feedstock of the reactor comprises ethylene glycol and ethylene oxide, and optionally diethylene glycol. As described above, according to some preferred embodiments of the present invention, the content of ethylene oxide in the feedstock of each stage of the reaction is no more than 15 wt%. The production target for the amount of ethylene glycol and diethylene glycol depends on the ratio of increased diethylene glycol and triethylene glycol production. If the primary production target is to increase diethylene glycol production, with a small increase in triethylene glycol production, then the reactor inlet feedstock only needs to contain monoethylene glycol. If the primary production target is to increase triethylene glycol production, then the reactor inlet feedstock contains both monoethylene glycol and diethylene glycol.

[0013] As mentioned above, if the primary production objective is to increase triethylene glycol production, the reactor inlet feedstock will contain both monoethylene glycol and diethylene glycol. The higher the proportion of diethylene glycol, the greater the increase in triethylene glycol production.

[0014] According to the present invention, the reaction liquid obtained in the previous stage is subjected to interstage heat removal before being used as the raw material for the next stage reaction; preferably, the interstage heat removal method is to cool the reaction liquid obtained in the previous stage.

[0015] According to the present invention, preferably, the inlet temperature of the reactor must reach the activation temperature, while taking into account the adiabatic temperature rise after the addition of ethylene oxide, so that the temperature after the reaction is within the target control range. More preferably, the feed temperature of each stage of the reaction is not less than 100°C, preferably between 100°C and 130°C.

[0016] According to some preferred embodiments of the present invention, the catalyst is selected from acids or bases, preferably bases, and more preferably sodium hydroxide and / or potassium hydroxide.

[0017] According to some preferred embodiments of the invention, the amount of catalyst used in the first-stage reaction is less than 0.5 wt% of the total weight of monoethylene glycol and ethylene oxide, and optionally diethylene glycol and triethylene glycol, based on the weight of the catalyst itself, preferably less than 0.1 wt%. For example, it can be 0.05 wt% to 0.1 wt%.

[0018] According to the present invention, the N-order reaction can be a 2nd-order, 3rd-order, 4th-order, 5th-order, etc. reaction; according to some preferred embodiments of the present invention, the N-order reaction is a 2nd-order or 3rd-order reaction, more preferably a 3rd-order reaction.

[0019] According to a preferred embodiment of the present invention, the reaction conditions of the last stage, i.e. the Nth stage reaction, are such that the concentration of ethylene oxide in the resulting reaction solution is less than 50 ppm, preferably less than 5 ppm.

[0020] According to the present invention, the EO concentration at the reactor outlet before the Nth stage can be controlled within a wide range. Considering that the cost increase is limited when the residence time is longer and the EO reaction is more thorough by extending the tubular reactor passage, the reaction is more preferably carried out under the reaction conditions of each stage such that the concentration of ethylene oxide in the reaction solution obtained after each stage is less than 50 ppm, preferably less than 5 ppm.

[0021] According to some preferred embodiments of the present invention, the reaction conditions for each stage of the reaction include:

[0022] The pressure is less than 3.0 MPaG; and / or the reaction inlet temperature is 100-130℃; and / or the residence time is 10 min-1 h, for example 10 min, 20 min, 30 min, 40 min, 1 h, or any two values ​​or any range of any two values.

[0023] According to a preferred embodiment of the present invention, the reaction is carried out in a tubular reactor, preferably in a multi-stage tubular reactor.

[0024] According to some preferred embodiments of the present invention, the reaction temperature is 100-120°C at the inlet and the outlet temperature is determined by the amount of ethylene oxide added. According to a preferred embodiment of the present invention, the reaction outlet temperature does not exceed 230°C, for example, around 170-200°C, not exceeding 230°C.

[0025] According to the present invention, after the N-stage reaction, a reaction solution containing monoethylene glycol, diethylene glycol, triethylene glycol and heavy alcohol is obtained, and then monoethylene glycol, diethylene glycol, triethylene glycol and heavy alcohol are obtained by separation.

[0026] According to some preferred embodiments of the present invention, the separation method is distillation; preferably, ethylene glycol, diethylene glycol, triethylene glycol and heavy alcohol are obtained sequentially through multiple distillation columns.

[0027] According to the present invention, the specific conditions for obtaining monoethylene glycol, diethylene glycol, triethylene glycol, and heavy alcohol sequentially through multiple distillation columns are existing technologies. These include, but are not limited to, the specific conditions described in the embodiments of the present invention.

[0028] According to a preferred embodiment of the present invention, the separated monoethylene glycol and optionally a portion of diethylene glycol are recycled back to the primary reaction as reactants.

[0029] A second aspect of the present invention is to provide a system for producing diethylene glycol and triethylene glycol, preferably used for the method for increasing the production of diethylene glycol and triethylene glycol as described in the first aspect, comprising: a multi-stage reactor connected in series: including: a primary reactor...N stage reactors, where N is an integer not less than 1;

[0030] The feed inlet of the primary reactor is connected to the feed sources of ethylene glycol, ethylene oxide, and optionally diethylene glycol catalyst via pipelines.

[0031] The feed inlets of the secondary and higher-level reactors are also connected to the ethylene oxide feedstock via pipelines.

[0032] The system also includes a monoethylene glycol tower, a diethylene glycol tower, and a triethylene glycol tower connected in series, wherein the bottom liquid outlet of the previous tower is connected to the feed inlet of the next tower;

[0033] Preferably, the multi-stage reactor is a multi-stage tubular reactor.

[0034] For an N-stage reactor, N can be 2, 3, 4, 5..., preferably 2 or 3.

[0035] According to some preferred embodiments of the present invention, a cooler is also provided on the pipeline between the two-stage reactors.

[0036] According to the present invention, the term "between two stages" refers to the position between two adjacent reactors in a continuous multi-stage reactor system.

[0037] According to some preferred embodiments of the present invention, the ethylene oxide feed line is connected to the feed line between the two-stage reactors; more preferably, the cooler is disposed on the line before it intersects with the ethylene oxide feed line.

[0038] According to some preferred embodiments of the present invention, the top outlets of the monoethylene glycol column and the diethylene glycol column are connected to the inlet of the primary reactor via pipelines.

[0039] According to some preferred embodiments of the present invention, a preheater is also provided on the pipeline before the feed inlet of the primary reactor.

[0040] According to some preferred embodiments of the present invention, the system further includes a tetraethylene glycol column, wherein the bottom liquid outlet of the triethylene glycol column is connected to the feed inlet of the tetraethylene glycol column.

[0041] This invention utilizes EO, EG, and optionally DEG in the presence of a catalyst to increase the production of diethylene glycol and triethylene glycol. By employing an interstage heat removal method and adding EO in stages, the amount of EO added can be increased to 45% of the feedstock (based on the total weight of the feedstock excluding ethylene oxide being 100%) while ensuring safety. This increases the yield of diethylene glycol and triethylene glycol, improves the conversion rate of EG and DEG, reduces the recycling volume of diethylene glycol and triethylene glycol, reduces energy consumption, and minimizes equipment size. Attached Figure Description

[0042] Figure 1 This is a process flow diagram for increasing the production of diethylene glycol and triethylene glycol.

[0043] 1. Catalyst feed pump; 2. EG feed pump; 3. EO feed pump; 4. Primary reactor feed preheater; 5. Primary reactor; 6. Primary reactor outlet cooler; 7. Secondary reactor; 8. Secondary reactor outlet cooler; 9. Tertiary reactor; 10. Monoethylene glycol tower; 11. Diethylene glycol tower; 12. Triethylene glycol tower; 13. Tetraethylene glycol tower;

[0044] like Figure 1As shown, the preferred technical solution adopted in this invention is as follows: A method and system for producing diethylene glycol and triethylene glycol, wherein EG is pressurized by a pump, mixed with monoethylene glycol from monoethylene glycol tower (10) and diethylene glycol from diethylene glycol tower (11), further mixed with a catalyst, and then preheated to the reaction temperature by a primary reactor feed preheater (4), and then mixed with EO. After mixing, it immediately enters the primary reactor (5), and then enters the primary reactor outlet cooler (6) for cooling. After mixing with another stream of EO, it immediately enters the secondary reactor (7). After entering the secondary reactor outlet cooler (8), it is cooled and mixed with another stream of EO before immediately entering the tertiary reactor (9). After the reaction, it enters the monoethylene glycol tower (10), where the unreacted EG is distilled off from the top of the tower and returned to the reactor. The bottom of the tower enters the diethylene glycol tower (11), where DEG is obtained at the top. Part of the DEG is collected, and part of the DEG is returned to the reaction system. The bottom of the tower enters the triethylene glycol tower (12), where triethylene glycol is obtained at the top of the triethylene glycol tower (12). The bottom of the tower enters the tetraethylene glycol tower (13), where tetraethylene glycol is collected at the top, and the bottom of the tower contains heavy alcohol. Detailed Implementation

[0045] The present invention will now be described in detail with reference to specific embodiments. It should be noted that the following embodiments are only used to further illustrate the present invention and should not be construed as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the content of the present invention are still within the scope of protection of the present invention.

[0046] In the following examples, the conversion rate of EG is calculated as: the mass of EG at the outlet of the last stage reactor / the mass of EG entering the reactor.

[0047] The DEG conversion rate is calculated as: DEG mass at the outlet of the last stage reactor / DEG mass entering the reactor.

[0048] Example 1

[0049] EG at 30°C and 999 kg / hr is pumped to 3.0 MPaG, preheated to 120°C by a heat exchanger, mixed with sodium hydroxide at 1 kg / hr, and then mixed with EO at 100 kg / hr and 20°C. The temperature is then reduced to 112°C, and the mixture enters the primary reactor at a pressure less than 2.95 MPaG. During this process, the EO is controlled to prevent vaporization. The reaction takes place in a tubular reactor, with a residence time of 25 minutes. After the reaction, the temperature rises to 172°C. The reaction solution composition is 79% EG, 18% DEG, 2.47% TEG, and 0.2% BEG, with an EO concentration of less than 10 ppm.

[0050] After the reaction solution is cooled to 120°C by a cooler, it is mixed with EO at 100 kg / hr at 20°C. The temperature then becomes 117°C and enters the secondary reactor at a pressure of less than 2.75 MPaG. During this process, the EO is controlled to prevent vaporization. The reaction takes place in a tubular reactor and after a residence time of 25 minutes, the temperature rises to 172°C. The composition of the reaction solution is 63.2% EG, 28.8% DEG, 7.38% TEG, and 0.55% BEG, with an EO concentration of less than 10 ppm.

[0051] After being cooled to 120°C, the mixture was mixed with EO at 100 kg / hr (20°C), and the temperature dropped to 114°C. The mixture then entered a three-stage reactor at a pressure less than 2.55 MPaG. During this process, the EO was controlled to prevent vaporization. The reaction took place in a tubular reactor, with a residence time of 25 minutes. After the reaction, the temperature rose to 168°C. The reaction solution composition was 51% EG, 32.7% DEG, 14.4% TEG, and 1.53% BEG, with an EO concentration of less than 10 ppm. The EG conversion rate was approximately 33%.

[0052] The product then enters the monoethylene glycol column, with an operating pressure of 6 kPaA and an operating temperature of 121°C, yielding 668 kg / hr of monoethylene glycol, which can be recycled back to the reactor. The product then enters the diethylene glycol column at a bottom temperature of 173°C, with an operating pressure of 2 kPaA and an operating temperature of 130°C, yielding 424 kg / hr of diethylene glycol. The product then enters the triethylene glycol column at a bottom temperature of 184°C, with an operating pressure of 0.1 kPaA and an operating temperature of 112°C, yielding 189 kg / hr of triethylene glycol at the top and 19 kg / hr of heavy alcohol at the bottom.

[0053] As can be seen from Example 1, the present invention utilizes the reaction of EO and EG under the action of a catalyst to increase the production of diethylene glycol and triethylene glycol. By adopting an interstage heat removal method and adding EO in stages, the amount of EO added is increased, thereby improving the conversion rate of EG and increasing the yield of diethylene glycol and triethylene glycol.

[0054] By comparing the composition of the reaction solution after the three-stage reaction in Example 1 with that after the first-stage reaction, it can be seen that the method of the present invention can significantly improve the conversion rate of EG and increase the production of DEG and TEG. Furthermore, as can be seen from the above implementation scheme, by using the preferred EO supplementation amount of the present invention, the reaction inlet temperature in the present invention is below 120°C, and the temperature of each stage after the reaction is below 175°C. It can be seen that not only is the conversion rate of EG and DEG improved, but the overall temperature is also controllable.

[0055] By comparing the composition of the reaction solution obtained after the third-stage reaction with that obtained after the second-stage reaction in Example 1, it can be seen that the third-stage reaction has a higher conversion rate of EG and DEG than the second-stage reaction using the method of the present invention. Therefore, it is preferable to use a three-stage continuous reaction.

[0056] Comparative Example 1

[0057] EG at 30°C and a flow rate of 999 kg / hr is pumped up to 3.0 MPaG, preheated to 120°C by a heat exchanger, and then mixed with sodium hydroxide at 1 kg / hr. This mixture is then mixed with EO at 450 kg / hr and a flow rate of 20°C, and enters the primary reactor at a pressure less than 2.95 MPaG. During this process, EO is controlled to prevent vaporization. The reaction takes place in a tubular reactor, with a residence time of 30 minutes. After the reaction, the temperature rises to 311°C. The reactor outlet composition is (EG 41.8%, DEG 23.17%, TEG 25.3%, PEG 9.57%). The high temperature of the entire reaction system results in a reactor capacity of 300 lbs, leading to a large equipment investment. Simultaneously, the large temperature rise and stress in the reactor pose a risk of stress-induced breakage of the tubular reactor.

[0058] Comparative Example 2

[0059] The procedure was carried out according to Example 1, except that after the first-stage reaction, no interstage heat removal was performed, and the reaction solution was directly introduced into the second-stage reactor. Other conditions were the same as in Example 1.

[0060] Without heat removal between stages, the final outlet temperature of the three-stage reactor is 253 degrees Celsius. Although the outlet concentration is close to that of Example 1, the reaction in each stage is too violent and difficult to control, posing a risk.

[0061] Example 2

[0062] EG at 30°C and a flow rate of 699 kg / hr is pumped to 3.1 MPaG, preheated to 120°C by a heat exchanger, mixed with 1 kg / hr of sodium hydroxide, then mixed with 300 kg / hr of diethylene glycol at 120°C and 3.0 MPaG, and finally mixed with 100 kg / hr of EO at 20°C. The temperature then becomes 123°C and enters the primary reactor at a pressure less than 2.9 MPaG. During this process, EO is controlled to prevent vaporization, and the residence time is 1 hour. After the reaction, the temperature rises to 181°C. The reaction solution contains 44.19% EG, 35.4% DEG, 16.2% TEG, and 4% BEG, with an EO concentration of less than 5 ppm.

[0063] After being cooled to 120°C by a cooler, it is mixed with EO at 20°C and 100 kg / hr. The temperature then becomes 112°C and enters the secondary reactor at a pressure of less than 2.7 MPaG. During this process, the EO is controlled to prevent vaporization, and the residence time is 1 hour. After the reaction, the temperature rises to 172°C. The composition of the reaction solution is 63.2% EG, 28.8% DEG, 7.38% TEG, and 0.55% BEG, with an EO concentration of less than 5 ppm.

[0064] After being cooled to 120°C by a cooler, it is mixed with EO at 20°C and 100 kg / hr. The temperature then becomes 112°C and enters a three-stage reactor at a pressure of less than 2.5 MPaG. During this process, the EO is controlled to prevent vaporization, and the residence time is 1 hour. After the reaction, the temperature rises to 170°C. The composition of the reaction solution is 35.3% EG, 34.6% DEG, 22.9% TEG, and 7.15% BEG, with an EO concentration of less than 5 ppm.

[0065] The product then enters the monoethylene glycol column, with an operating pressure of 6 kPaA and an operating temperature of 121°C, yielding 460 kg / hr of monoethylene glycol, which can be recycled back to the reactor. The product then enters the diethylene glycol column at a bottom temperature of 177°C, with an operating pressure of 2 kPaA and an operating temperature of 132°C, yielding 448 kg / hr of diethylene glycol. The product then enters the triethylene glycol column at a bottom temperature of 186°C, with an operating pressure of 0.1 kPaA and an operating temperature of 112°C, yielding 302 kg / hr of triethylene glycol at the top and 90 kg / hr of heavy alcohol at the bottom.

[0066] As shown in Example 2, the present invention utilizes the reaction of EO with EG and DEG under the action of a catalyst to increase the production of diethylene glycol and triethylene glycol. By adopting an interstage heat removal method and adding EO in stages, the amount of EO added is increased, the conversion rate of EG and DEG is increased, and the yield of diethylene glycol and triethylene glycol is increased.

[0067] By comparing the composition of the reaction solution after the third-stage reaction in Example 2 with that after the first-stage reaction, it can be seen that the method of the present invention can significantly improve the conversion rate of DEG and EG. Furthermore, as shown in the above implementation scheme, by using the preferred EO supplementation amount of the present invention, the reaction inlet temperature in the present invention is below 123°C, and the temperature of each stage after the reaction is below 181°C. It can be seen that not only is the conversion rate of EG and DEG improved, but the overall temperature is also controllable.

[0068] By comparing the composition of the reaction solution obtained after the third-stage reaction with that obtained after the second-stage reaction in Example 2, it can be seen that the third-stage reaction has a higher conversion rate of EG and DEG than the second-stage reaction using the method of the present invention. Therefore, it is preferable to use a three-stage continuous reaction.

[0069] A comparison of Examples 1 and 2 shows that Example 1, using EO and EG as raw materials, has a greater advantage in increasing EG production, while Example 2, using EO, EG, and DEG as raw materials, has a greater advantage in increasing DEG production. Using the method of this invention, the selection of raw materials can be adjusted according to production targets, resulting in significant technical effects.

[0070] As can be seen from the comparison of the examples and comparative examples, the present invention not only increases the yield of diethylene glycol and triethylene glycol, but also ensures controllable safety, achieving unexpected technical effects.

[0071] It should be noted that the embodiments described above are only for explaining the present invention and do not constitute any limitation on the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory terms, not limiting terms. Modifications can be made to the present invention within the scope of the claims, and revisions can be made to the present invention without departing from the scope and spirit of the present invention. Although the present invention described herein relates to specific methods, materials, and embodiments, it does not mean that the present invention is limited to the specific examples disclosed herein; on the contrary, the present invention can be extended to all other methods and applications with the same function.

[0072] All publications, patent applications, patents, and other references mentioned in this specification are incorporated herein by reference. Unless otherwise defined, all technical and scientific terms used in this specification have the meanings commonly understood by those skilled in the art. In case of conflict, the definitions in this specification shall prevail.

[0073] When this specification uses the prefixes “known to those skilled in the art,” “prior art,” or similar terms to derive materials, substances, methods, steps, apparatus, or components, the objects derived from such prefixes cover those commonly used in the art at the time of this application, but also include those that are not currently commonly used but will become generally recognized in the art as suitable for similar purposes.

[0074] The endpoints and any values ​​of the ranges disclosed in this application are not limited to the precise ranges or values; such ranges or values ​​should be understood to include values ​​close to them. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein. In principle, various technical solutions can be combined with each other to obtain new technical solutions, which should also be considered as specifically disclosed herein.

[0075] In the context of this specification, except where expressly stated otherwise, any matters or issues not mentioned shall apply directly to those known in the art without any modification.

[0076] Furthermore, any implementation described herein can be freely combined with one or more other implementations described herein, and the resulting technical solutions or technical ideas shall be regarded as part of the original disclosure or original record of the present invention, and should not be regarded as new content not disclosed or anticipated herein, unless those skilled in the art consider the combination to be obviously unreasonable.

Claims

1. A method for increasing the production of diethylene glycol and triethylene glycol, comprising carrying out an N-stage reaction of monoethylene glycol, ethylene oxide, and optionally diethylene glycol in the presence of a catalyst, wherein N is an integer not less than 2, subjecting the reaction solution obtained from the previous stage to interstage deheating and adding ethylene oxide before proceeding to the next stage reaction, and obtaining a reaction solution containing monoethylene glycol, diethylene glycol, triethylene glycol, and heavy alcohol after the N-stage reaction, and then separating monoethylene glycol, diethylene glycol, triethylene glycol, and heavy alcohol.

2. The method according to claim 1, characterized in that: In the feedstock of each reaction stage, the content of ethylene oxide is no more than 15 wt%.

3. The method according to claim 1, characterized in that: The method of heat removal between stages is to cool the reaction liquid obtained from the previous stage; more preferably, The feed temperature for each stage of the reaction should be no less than 100℃, preferably between 100℃ and 130℃.

4. The method according to claim 1, characterized in that: The catalyst is selected from acids or bases, preferably bases, more preferably sodium hydroxide and / or potassium hydroxide; and / or, Based on the weight of the catalyst itself, the amount of catalyst used in the first-order reaction is less than 0.5 wt% of the total weight of monoethylene glycol and ethylene oxide, and optionally diethylene glycol and triethylene glycol, preferably less than 0.1 wt%.

5. The method according to any one of claims 1-4, characterized in that: The Nth-order reaction is a 3rd-order reaction; and / or, The reaction conditions for each stage of the reaction are such that the concentration of ethylene oxide in the reaction solution obtained after each stage of the reaction is less than 50 ppm, preferably less than 5 ppm.

6. The method according to claim 5, characterized in that: The reaction conditions for each order of reaction include: The pressure is less than 3 MPaG; and / or, the reaction inlet temperature is 100-130℃; the reaction outlet temperature does not exceed 230℃; and / or, The residence time is 10 min to 1 h; and / or the reaction is carried out in a tubular reactor.

7. The method according to claim 1, characterized in that: The separation method is distillation; preferably, it involves sequentially obtaining monoethylene glycol, diethylene glycol, triethylene glycol, and heavy alcohol through multiple distillation columns; and / or, The separated monoethylene glycol and an optional portion of diethylene glycol are recycled back to the first-order reaction.

8. A system for producing diethylene glycol and triethylene glycol, preferably used in the method for increasing the production of diethylene glycol and triethylene glycol according to any one of claims 1-7, comprising: A series of interconnected reactors: including: a primary reactor...N reactors, where N is an integer not less than 1; The feed inlet of the primary reactor is connected to the raw material sources of ethylene glycol, ethylene oxide, optional diethylene glycol, and catalyst via pipelines. The feed inlets of the secondary and higher-level reactors are also connected to the ethylene oxide feedstock via pipelines. The system also includes a monoethylene glycol tower, a diethylene glycol tower, and a triethylene glycol tower connected in series, wherein the bottom liquid outlet of the previous tower is connected to the feed inlet of the next tower; Preferably, the multi-stage reactor is a multi-stage tubular reactor.

9. The system according to claim 8, characterized in that: A cooler is also installed on the pipeline between the two reactors; and / or, The ethylene oxide feed line is connected to the feed line between the two-stage reactors; Preferably, the cooler is located on the pipeline before it intersects with the ethylene oxide feed line.

10. The system according to claim 8, characterized in that: The top outlets of the monoethylene glycol column and the diethylene glycol column are connected to the inlet of the primary reactor via pipelines; and / or, A preheater is also installed on the pipeline before the feed inlet of the primary reactor; and / or, The system also includes a tetraethylene glycol tower, and the bottom liquid outlet of the triethylene glycol tower is connected to the feed inlet of the tetraethylene glycol tower.

Images