Polyether purification apparatus and method

Abstract

This invention provides a polyether purification apparatus and method. The apparatus includes a condenser, a pressure controller, a vacuum system, and an absorption tower connected in sequence, and a purification tower connected to the absorption tower. The condenser's inlet is connected to the gas phase outlet of the polyether reactor; the condenser's non-condensable gas outlet is connected to the absorption tower's inlet pipeline; the pressure controller and a positive pressure valve are installed on this pipeline, and a bypass pipeline connecting the pressure controller and the positive pressure valve is connected to the absorption tower's inlet. A vacuum valve and a vacuum system are sequentially installed on the bypass pipeline. Thus, the pressure controller controls the positive pressure valve, vacuum valve, and vacuum system to send the non-condensable gas from the condenser into the absorption tower. The purification tower's inlet is connected to the bottom material outlet of the polyether reactor, and the purification tower's top exhaust port is connected to the absorption tower's inlet. This invention provides an apparatus that effectively removes a large amount of unreacted ethylene oxide remaining in polyether products and purifies the polyether products, resulting in better polyether quality and solving the safety and economic issues in polyether production.

Description

Technical Field

[0001] This invention relates to the field of polyether synthesis technology, and more specifically, to a polyether purification apparatus and method. Background Technology

[0002] Polyether macromonomers, as commonly used initiators for polyether polyols, play a crucial role in the production of polyurethane products. With the booming global economy and continuous advancements in industrial technology, the market demand for high-performance polyurethane products is growing, creating significant market opportunities for high-purity polyether macromonomers.

[0003] In the production of polyether macromonomers, the low conversion rate of ethylene oxide feedstock has always been a major challenge for process researchers. Residual ethylene oxide monomers not only severely affect product quality but also pose a threat to equipment safety, significantly hindering its promotion and application in the high-end market.

[0004] Therefore, developing an efficient and safe purification process for polyether macromonomers is of great significance for improving product purity, stability, and safety. Summary of the Invention

[0005] To address the aforementioned problems, this invention provides a polyether purification apparatus and method that can effectively remove a large amount of unreacted ethylene oxide remaining in polyether products, purify the polyether products, improve their quality and safety for application, and ensure the safety of polyether products during storage and transportation.

[0006] Firstly, one of the objectives of this invention is to provide a polyether purification apparatus.

[0007] Specifically, the apparatus includes a condenser, a pressure controller, a vacuum system, and an absorption tower connected in sequence, and a purification tower connected to the absorption tower.

[0008] The condenser is used to cool the gaseous material (mainly ethylene oxide and non-condensable gas) discharged from the polyether reactor, separating it into condensate (mainly ethylene oxide) and non-condensable gas. The condensate is discharged for recycling, and the non-condensable gas is sent to the absorption tower for purification.

[0009] Specifically, the condenser's inlet is connected to the gas phase outlet of the polyether reactor; the condenser's non-condensable gas outlet is connected to the inlet pipeline of the absorption tower; a pressure controller and a positive pressure valve are installed on this pipeline, and a bypass pipeline is also installed between the pressure controller and the positive pressure valve, connecting to the inlet of the absorption tower. A vacuum valve and a vacuum system are sequentially installed on the bypass pipeline; thus, the non-condensable gas in the condenser is sent into the absorption tower by controlling the positive pressure valve, vacuum valve, and vacuum system through the pressure controller. Furthermore, the condenser is also equipped with a liquid phase outlet for discharging condensate.

[0010] It is worth mentioning that when the pressure controller monitors the pressure in real time and it is higher than the equilibrium pressure, the non-condensable gas enters the absorption tower through the positive pressure valve; when the pressure controller monitors the pressure in real time and it is lower than or equal to the equilibrium pressure, the vacuum system is activated, sending ethylene oxide, non-condensable gas, and a small amount of small molecule aldehydes in the device into the absorption tower through the vacuum valve. This invention can completely remove and recover ethylene oxide in the polyether reactor by controlling the pathway of non-condensable gas entering the absorption tower.

[0011] More specifically, the feed inlet of the refining tower is connected to the bottom material outlet of the polyether reactor, and the exhaust outlet at the top of the refining tower is connected to the air inlet of the absorption tower.

[0012] It is worth mentioning that the refining tower is used to receive the liquid material discharged from the polyether reactor and remove residual impurities (mainly aldehydes) contained in the crude polyether. In the refining tower, the residual impurities form a gaseous stream that enters the absorption tower, while the refined polyether product is discharged through the polyether product outlet set in the bottom of the refining tower.

[0013] Furthermore, the absorption tower's inlet includes a first inlet, a second inlet, and a third inlet. A pipeline equipped with a pressure controller and a positive pressure valve is connected to the first inlet, with the positive pressure valve located at the first inlet. A bypass pipeline is connected to the second inlet, and a vacuum valve and vacuum system are sequentially located at the second inlet. The exhaust port at the top of the purification tower is connected to the third inlet. That is, the first and second inlets are used to receive non-condensable gases discharged from the condenser, while the third inlet is used to receive gaseous materials discharged from the purification tower.

[0014] It is worth mentioning that the first and second air inlets can be the same inlet on the absorption tower, or they can be different inlets on the absorption tower. In practical applications, the configuration can be determined according to the application requirements.

[0015] In a preferred embodiment of the present invention, the absorption tower is provided with a waste gas outlet at the top, an absorbent inlet at the top, and a waste liquid outlet at the bottom. The absorption tower is used to purify non-condensable gases and absorb impurities and other waste liquids. The waste gas outlet of the absorption tower is used to discharge the purified non-condensable gases and other waste gases. The absorbent inlet of the absorption tower is used to continuously replenish the absorption tower with absorbent liquid for absorbing various impurities. The waste liquid outlet of the absorption tower is used to discharge waste liquid.

[0016] In a preferred embodiment of the present invention, the device further includes a condensate collection tank, the inlet of which is connected to the liquid phase outlet of the condenser, and the bottom of the condensate collection tank is provided with an outlet for discharging ethylene oxide.

[0017] In another preferred embodiment of the present invention, the top of the condensate collection tank is provided with an exhaust port, which is connected to the pipeline at the non-condensable gas outlet of the condenser. That is, the non-condensable gas discharged from the condensate collection tank and the non-condensable gas discharged from the condenser are mixed and then enter the absorption tower.

[0018] In another preferred embodiment of the present invention, the condensate collection tank is provided with an inner coil for controlling the temperature inside the condensate collection tank. Chilled water flows through the inner coil.

[0019] It is worth mentioning that the pressure controller controls the path of gaseous material entering the absorption tower by controlling the opening or closing of the positive pressure valve, vacuum valve, and vacuum system.

[0020] In a preferred embodiment of the present invention, the apparatus further includes water and a reactor, the inlet of which is connected to the waste liquid outlet of the absorption tower, and the outlet of which is connected to the absorbent inlet of the absorption tower. The water and reactor are filled with a catalyst capable of hydrolyzing residual ethylene oxide in the waste liquid, which is then absorbed by the absorbent and discharged.

[0021] The absorbent can be any absorbent commonly used in existing technologies for absorbing impurities. Preferably, the absorbent is selected from one or a combination of water, ethanol, and methanol. The catalyst can be a common catalyst for the hydration reaction of ethylene oxide, such as a molecular sieve carboxylic acid catalyst. Optionally, the molecular sieve carboxylic acid catalyst is niobium-modified ZSM-5 zeolite, referring to the catalyst in the prior art literature: Yang Zhijian, "Development and Research of High-Efficiency Catalyst for Catalytic Hydration of Ethylene Oxide to Ethylene Glycol," Master's Thesis, Fudan University.

[0022] In a preferred embodiment of the present invention, the refining tower is a multi-stage stripping refining tower, and the stripping steam used in the multi-stage stripping refining tower is one or a combination of nitrogen and low-pressure water vapor.

[0023] In a preferred embodiment of the present invention, a temperature controller is provided at the liquid phase outlet of the condenser. The temperature controller can control the liquid phase outlet temperature of the condenser according to the real-time pressure change of the gaseous material, so as to maximize the collection of ethylene oxide.

[0024] Secondly, a second objective of this invention is to provide a method for purifying polyethers.

[0025] Specifically, the method is carried out using an apparatus that achieves one of the objectives of this invention, and the specific steps are as follows:

[0026] The gaseous material discharged from the polyether reactor is condensed and separated into condensate and non-condensable gas. The condensate is sent out, and the non-condensable gas enters the absorption tower under the control of the pressure controller. The liquid material in the polyether reactor is purified and separated into gaseous material and polyether product. The gaseous material enters the absorption tower, and the polyether product is sent out.

[0027] The method by which the pressure controller controls the positive pressure valve, vacuum valve, and vacuum system is as follows:

[0028] When P / P 平衡 >1. The pressure controller controls the positive pressure valve to open and the vacuum valve and vacuum system to close, allowing gaseous materials to enter the absorption tower through the positive pressure valve;

[0029] When P / P 平衡 ≤1, the pressure controller controls the positive pressure valve to close, and the vacuum valve and vacuum system to open, so that the gaseous material enters the absorption tower through the vacuum valve and vacuum system;

[0030] P represents the real-time pressure detected online by the pressure controller. 平衡 This is the balancing pressure of the device.

[0031] Preferably, P 平衡 The range is 0–5 kPaG, preferably 0–3 kPaG.

[0032] In a preferred embodiment of the present invention, the method for controlling the liquid phase outlet temperature of the condenser is as follows:

[0033] When P / P 平衡 >1. The liquid phase outlet temperature of the condenser is set to be greater than 0℃ and less than or equal to 5℃;

[0034] When P / P 平衡 ≤1, the liquid phase outlet temperature of the condenser is set to -10~0℃.

[0035] It is worth mentioning that the lower the pressure, the lower the dew point temperature at which ethylene oxide condenses from the gas phase to the liquid phase, and the lower the pressure at different P / P ratios. 平衡 The control of the liquid phase outlet temperature of the condenser is also different, in order to collect ethylene oxide to the greatest extent.

[0036] In a preferred embodiment of the present invention, the temperature inside the condensate collection tank is 3-5°C lower than that at the liquid phase outlet of the condenser. The present invention stabilizes the ethylene oxide in the condensate collection tank by controlling it to be a subcooled liquid, thus preventing it from evaporating.

[0037] In a preferred embodiment of the present invention, the mass ratio of liquid material to stripping steam introduced into the refining tower is 10 to 30; preferably 15 to 20.

[0038] In a preferred embodiment of the present invention, the weight ratio between the absorbent liquid introduced into the absorption tower and the gas entering the absorption tower is controlled as follows:

[0039] When P / P 平衡 >1, the weight ratio of absorbent to gas is 20-30;

[0040] When P / P 平衡 ≤1, the weight ratio of absorbent to gas is 10 to 20.

[0041] Compared with the prior art, the present invention has the following beneficial effects:

[0042] 1. The polyether purification method provided by this invention is simple and efficient, requiring no additional deoxygenation device. By controlling the gas phase valve through pressure control parameters, the in-situ removal of ethylene oxide residue in the polyether product is achieved, thus solving the safety and economic problems in polyether production.

[0043] 2. This invention achieves automatic control of the parameters of the condenser, condensate collection tank, and absorption tower through pressure control, ensuring the efficient operation of the process and maximizing the recovery of ethylene oxide and the removal of impurities from polyether products.

[0044] 3. This invention combines pressure and temperature control to collect ethylene oxide, maximizing the recovery and reuse of unreacted ethylene oxide.

[0045] 4. This invention, through the combined use of an absorption tower and a hydration reactor, can efficiently decompose and absorb unrecoverable ethylene oxide tail gas, thus preventing ethylene oxide from being released into the atmosphere.

[0046] 5. The purified polyether product provided by this invention has a purity of over 99%, and aldehyde impurities are controlled at the PPM level. Attached Figure Description

[0047] Figure 1 This is a process flow diagram of the polyether purification device provided in Embodiment 5 of the present invention;

[0048] Explanation of reference numerals in the attached figures:

[0049] R-101, polyether reactor; E-101, condenser; V-101, condensate collection tank; PC, pressure controller; V1, positive pressure valve; V2, vacuum valve; PA-101, vacuum system; T-101, absorption tower; T-102, purification tower; R-102, hydration reactor; 111-134 are connecting pipelines, and the materials flowing through the different pipelines are as follows:

[0050] 111. Gas phase material discharged from the top of the polyether reactor tower;

[0051] 112. Non-condensable gases discharged from the condenser;

[0052] 113. Positive pressure non-condensable materials

[0053] 114. Non-condensable gas materials under negative pressure

[0054] 115. The liquid phase discharged from the condenser (condensate);

[0055] 116. The vapor phase discharged from the condensate storage tank;

[0056] 117. The liquid phase (condensate) discharged from the condensate storage tank;

[0057] 121. Discharge from the bottom of the polyether reactor tower;

[0058] 122. Stripping steam from the refining tower;

[0059] 123. Polyether products

[0060] 124. Gaseous material is discharged from the top of the refining tower;

[0061] 131. Absorbent solution;

[0062] 132. Waste gas at the top of the absorption tower;

[0063] 133. Waste liquid at the bottom of the absorption tower;

[0064] 134. Waste liquid from the bottom of the absorption tower is discharged externally. Detailed Implementation

[0065] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, 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. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0066] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0067] It should be noted that similar symbols and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0068] In the description of this invention, it should be noted that the terms "upper," "lower," "left," "right," "inner," "outer," "front," and "rear," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the product of this invention is usually placed during use. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0069] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "setting," "connection," etc., should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be a connection within two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0070] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0071] Example 1

[0072] This embodiment is used to illustrate a polyether purification apparatus. Figure 1 A process flow diagram of the device is shown.

[0073] As shown in the figure, the apparatus disclosed in this embodiment includes a polyether reactor R-101, a condenser E-101, a pressure controller PC, an absorption tower T-101, and a purification tower T-102.

[0074] The condenser E-101 is equipped with a feed inlet, a liquid phase outlet, and a non-condensable gas outlet. The feed inlet of the condenser E-101 is connected to the gas phase outlet of the polyether reactor R-101 through pipeline 111. A large amount of unreacted ethylene oxide remaining in the polyether reactor R-101 is discharged from the gas phase outlet of the polyether reactor R-101. The gas phase material containing non-condensable gas and ethylene oxide enters the condenser E-101 and is separated into liquid phase ethylene oxide and gas phase non-condensable gas. Ethylene oxide is discharged from the liquid phase outlet of the condenser E-101, and the gas phase material (mainly non-condensable gas) is discharged from the gas outlet of the condenser E-101.

[0075] Furthermore, the pressure controller PC is positioned between the condenser E-101 and the absorber T-101. It controls the path of non-condensable gas entering the absorber T-101 by controlling the opening and closing of the positive pressure valve V1, vacuum valve V2, and vacuum system PA-101. Specifically, in the initial stage of gaseous stream extraction from the polyether reactor R-101, the pressure in the polyether reactor is high. The pressure controller PC controls the positive pressure valve V1 to open and the vacuum valve V2 and vacuum system PA-101 to close. The non-condensable gas separated in the condenser E-101 enters the absorber T-101 through the positive pressure valve V1. As the non-condensable gas is extracted, the pressure in the polyether reactor decreases to or below the equilibrium pressure. The pressure controller PC controls the positive pressure valve V1 to close and the vacuum valve V2 and vacuum system PA-101 to open. The remaining non-condensable gas, ethylene oxide, and a small amount of low-molecular-weight aldehyde impurities in the polyether reactor R-101 enter the absorber T-101 through the vacuum valve V2.

[0076] This invention ensures the full condensation and collection of ethylene oxide through the regulation of the pressure controller PC, and can also remove residual ethylene oxide from polyether products as much as possible.

[0077] Specifically, the pressure controller PC is installed on pipeline 112, which connects the non-condensable gas outlet of condenser E-101 and the inlet of absorber T-101. Pipeline 112 is connected to pipelines 113 and 114, which are in turn connected to the inlet of absorber T-101. A positive pressure valve V1 is installed on pipeline 113, and a vacuum valve V2 and a vacuum system PA-101 are sequentially installed on pipeline 114. The pressure controller PC controls the opening or closing of the positive pressure valve V1, vacuum valve V2, and vacuum system PA-101 to allow non-condensable gas to enter absorber T-101 through pipelines 113 or 114, respectively.

[0078] Furthermore, the refining tower T-102 is used to receive the liquid material discharged from the polyether reactor R-101 and remove residual impurities (mainly aldehyde impurities) contained in the crude polyether product to obtain a purer polyether product. Specifically, the refining tower T-102 is provided with a feed inlet, an exhaust outlet, and a product outlet. The feed inlet of the refining tower T-102 is connected to the material outlet of the bottom of the polyether reactor R-101 through pipeline 121, the exhaust outlet of the refining tower T-102 is connected to the air inlet of the absorption tower T-101 through pipeline 124, and the polyether product is discharged through pipeline 123.

[0079] Furthermore, the absorption tower T-101 is used to receive the gaseous material conveyed by the condenser E-101 and the refining tower T-102, and separate the gaseous material into waste gas and waste liquid for discharge, wherein both the waste gas and waste liquid meet the emission standards.

[0080] Example 2

[0081] This embodiment is used to illustrate a polyether purification apparatus. Figure 1 A process flow diagram of the apparatus of this embodiment is shown.

[0082] As shown in the figure, this embodiment, based on Embodiment 1, further discloses a condensate collection tank V-101. The inlet of the condensate collection tank V-101 is connected to the liquid phase outlet of the condenser E-101 via pipeline 115, and ethylene oxide liquid is collected within the condensate collection tank V-101. Simultaneously, the bottom of the condensate collection tank V-101 is provided with a discharge outlet for discharging the ethylene oxide collected within the condensate collection tank V-101 through pipeline 117. Ethylene oxide can be recycled to save resources and reduce production costs.

[0083] Furthermore, the top of the condensate collection tank V-101 in this embodiment is also provided with an exhaust port, which is connected to the pipeline 112 through the pipeline 116. After the gaseous stream discharged from the condenser E-101 in the condensate collection tank V-101 is mixed, it enters the absorption tower T-101.

[0084] Furthermore, the condensate collection tank V-101 is also equipped with an inner coil, through which chilled water circulates to regulate the temperature inside the condensate collection tank V-101.

[0085] In this embodiment, the non-condensable gas in the liquid phase ethylene oxide can be further discharged through the condensate collection tank V-101, and the ethylene oxide can be stored and recovered.

[0086] Example 3

[0087] This embodiment is used to illustrate a polyether purification apparatus. Figure 1 A process flow diagram of the apparatus of this embodiment is shown.

[0088] As shown in the figure, this embodiment, based on Embodiment 1, further discloses that the air inlet of the absorption tower T-101 includes a first air inlet and a second air inlet, both used to receive gaseous material discharged from the condenser E-101. A positive pressure valve V1 is installed on pipeline 113 and connected to the first air inlet; a vacuum valve V2 and a vacuum system PA-101 are sequentially installed on pipeline 114 and connected to the second inlet. The air inlet configuration of the absorption tower T-101 can be adjusted according to the actual application.

[0089] Example 4

[0090] This embodiment is used to illustrate a polyether purification apparatus. Figure 1 A process flow diagram of the apparatus of this embodiment is shown.

[0091] As shown in the figure, this embodiment, based on embodiment 3, further discloses that the absorption tower T-101 is equipped with a waste gas outlet at the top, an absorbent inlet at the top, and a waste liquid outlet at the bottom. The absorbent transported by pipeline 131 is continuously replenished into the absorption tower T-101 through the absorbent inlet. The absorbent passes through the packing material inside the tower and is used to purify non-condensable gases and absorb various impurities before being discharged. The purified non-condensable gas is discharged from the waste gas outlet at the top of the absorption tower T-101 through pipeline 132, while the waste liquid that has absorbed various impurities is discharged from the waste liquid outlet at the bottom of the absorption tower T-101 through pipelines 133 and 134.

[0092] The T-101 absorption tower purifies non-condensable gases and absorbs impurities.

[0093] Example 5

[0094] This embodiment is used to illustrate a polyether purification apparatus. Figure 1 A process flow diagram of the apparatus of this embodiment is shown.

[0095] As shown in the figure, this embodiment, based on Embodiment 2, further discloses a water and reactor R-102. The inlet of the water and reactor R-102 is connected to the waste liquid outlet of the absorption tower T-101 via pipeline 133. The water and reactor R-102 is filled with a molecular sieve carboxylic acid catalyst, which absorbs the ethylene oxide gas phase. The ethylene oxide is decomposed and discharged. The outlet of the water and reactor R-102 is connected to pipeline 131. The material in the water and reactor R-102 is mixed with the absorbent and then re-enters the absorption tower T-101 for separation.

[0096] Water and reactor R-102 efficiently decompose and absorb unrecoverable ethylene oxide tail gas, preventing ethylene oxide from being released into the atmosphere.

[0097] In this embodiment, the molecular sieve-type carboxylic acid catalyst is niobium-modified ZSM zeolite. Its preparation method is based on Chapter 4, Synthesis of Niobium-Modified ZSM-5 Zeolite, of the Master's Thesis of Fudan University, "Development and Research of High-Efficiency Catalyst for Ethylene Oxide Catalytic Hydration to Ethylene Glycol", authored by Yang Zhijian.

[0098] Example 6

[0099] This embodiment is used to illustrate a polyether purification apparatus. Figure 1 A process flow diagram of the apparatus of this embodiment is shown.

[0100] As shown in the figure, this embodiment further discloses that the refining tower T-101 is a multi-stage stripping refining tower, based on embodiment 1. The stripping vapor delivered to the refining tower T-101 through pipeline 122 undergoes stripping refining with the polyether product. The separated gaseous stream (mainly composed of aldehyde impurities, non-condensable gas, and stripping vapor) enters the absorption tower T-101 through the third air inlet of the absorption tower T-101 through pipeline 124. The purified polyether product is sent out through pipeline 123.

[0101] Example 7

[0102] This embodiment illustrates a polyether purification method, according to the appendix. Figure 1 The polyether purification apparatus and process flow of the present invention shown in Examples 1-6, and the specific parameters of the polyether purification method of the present invention are as follows:

[0103] Inside the polyether reactor R-101: After the reaction is complete, the pressure inside the polyether reactor R-101 is 0.4 MPaG, and the gaseous materials include non-condensable gas, ethylene oxide, and low molecular weight aldehydes.

[0104] During the gaseous stream extraction process within the polyether reactor R-101, the operating modes of the pressure controller PC, condenser E-101, condensate collection tank V-101, and absorption tower T-101 are as follows:

[0105] The equilibrium pressure of the gaseous stream in the device is 3 kPaG, and the real-time pressure P / P of the gaseous stream detected by pipeline 112 is... 平衡 When the pressure is >1, the pressure controller PC controls the positive pressure valve V1 to open, and the vacuum valve V2 and vacuum system PA-101 to close. The gaseous material enters the absorption tower T-101 through pipeline 113. The liquid outlet temperature of the condenser E-101 is controlled between 2 and 4°C by the temperature controller. The temperature in the condensate collection tank V-101 is controlled between -1 and 1°C by the internal coil. The mass ratio of the absorbed liquid to the gas is 25.

[0106] When the pressure P / P of the gaseous flow is monitored in real time 平衡When the pressure is ≤1, the pressure controller PC controls the positive pressure valve V1 to close, and the vacuum valve V2 and vacuum system PA-101 to open, and the material enters the absorption tower T-101 through pipeline 114; the liquid phase outlet temperature of the condenser E-101 is controlled between -7 and -5℃ by the temperature controller, and the temperature in the condensate collection tank V-101 is controlled between -11 and -8℃ by the internal coil; the mass ratio of the absorbed liquid to the discharged waste gas is 15, and the absorbed liquid is a mixture of water and methanol.

[0107] After the gaseous stream in the polyether reactor R-101 is extracted, the operation of the purification tower T-102 is as follows: In the purification tower T-102: the stripping steam introduced into the purification tower T-102 is low-pressure water vapor; the mass ratio of the introduced liquid material to the stripping steam is 20, and the mass ratio of the introduced absorbent to the discharged tail gas is 15.

[0108] After the gas stripping process, the purity of the obtained polyether product was 99.995%, the aldehyde impurity content was 50 PPM, and the ethylene oxide recovery rate was 93%.

[0109] Example 8

[0110] This embodiment illustrates a polyether purification method, according to the appendix. Figure 1 The polyether purification apparatus and process flow of the present invention shown in Examples 1-6, and the purification method and specific parameters of the polyether of the present invention are as follows:

[0111] Inside the polyether reactor R-101: After the reaction is complete, the pressure inside the polyether reactor R-101 is 0.45 MPaG, and the gaseous materials include non-condensable gases, ethylene oxide, and low molecular weight aldehydes.

[0112] During the gaseous stream extraction process within the polyether reactor R-101, the operating modes of the pressure controller PC, condenser E-101, condensate collection tank V-101, and absorption tower T-101 are as follows:

[0113] The equilibrium pressure of the gaseous stream in the device is 1 kPaG, and the real-time pressure P / P of the gaseous stream detected by pipeline 112 is... 平衡 When the pressure is >1, the pressure controller PC controls the positive pressure valve V1 to open, and the vacuum valve V2 and vacuum system PA-101 to close. The gaseous material enters the absorption tower T-101 through pipeline 113. The liquid outlet temperature of the condenser E-101 is controlled between 0 and 3°C by the temperature controller. The temperature in the condensate collection tank V-101 is controlled between -5 and -1°C by the internal coil. The mass ratio of the absorbed liquid to the gas is 30.

[0114] When the pressure P / P of the gaseous flow is monitored in real time 平衡When the pressure is ≤1, the pressure controller PC controls the positive pressure valve V1 to close, and the vacuum valve V2 and vacuum system PA-101 to open, and the material enters the absorption tower T-101 through pipeline 114; the liquid phase outlet temperature of the condenser E-101 is controlled between -10 and -8℃ by the temperature controller, and the temperature in the condensate collection tank V-101 is controlled between -15 and -11℃ by the internal coil; the mass ratio of the absorbed liquid to the discharged waste gas is 20, and the absorbed liquid is a mixture of water and methanol.

[0115] After the gaseous stream in polyether reactor R-101 is extracted, the purification tower T-102 operates as follows:

[0116] Inside the refining tower T-102: the stripping steam introduced into the refining tower T-102 is low-pressure water vapor; the mass ratio of the introduced liquid phase material to the stripping steam is 25; the mass ratio of the introduced absorbent liquid to the discharged tail gas is 20.

[0117] After the gas stripping process, the purity of the obtained polyether product was 99.999%, the aldehyde impurity content was 40 PPM, and the ethylene oxide recovery rate was 95%.

[0118] Comparative Example 1

[0119] The difference between the apparatus used in this comparative example and that used in Example 7 is that the apparatus in this comparative example does not include a pressure controller PC, and the gaseous material discharged from the condenser E-101 and the condensate collection tank V-101 directly enters the absorption tower T-101.

[0120] Inside the polyether reactor R-101: After the reaction is complete, the pressure inside the polyether reactor R-101 is 0.4 MPaG, and the gaseous materials include non-condensable gas, ethylene oxide, and low molecular weight aldehydes.

[0121] During the gaseous stream extraction process within the polyether reactor R-101, the operation of the condenser E-101, the condensate collection tank V-101, and the absorption tower T-101 is as follows:

[0122] The liquid outlet temperature of condenser E-101 is controlled between 2 and 4°C by a temperature controller; the temperature inside condensate collection tank V-101 is controlled between -1 and 1°C by an internal coil; the mass ratio of the absorbed liquid to the gas introduced is 25.

[0123] After the gaseous stream in polyether reactor R-101 is extracted, the purification tower T-102 operates as follows:

[0124] Inside the refining tower T-102: the stripping steam introduced into the refining tower T-102 is low-pressure water vapor; the mass ratio of the introduced liquid material to the stripping steam is 20; the mass ratio of the introduced absorbent to the discharged tail gas is 15.

[0125] After the gas stripping process, the purity of the obtained polyether product was 90%, the aldehyde impurity content was 200 PPM, and the ethylene oxide recovery rate was 70%.

[0126] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

[0127] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A polyether purification apparatus, comprising a condenser, a pressure controller, a vacuum system and an absorption tower connected in sequence, and a purification tower connected to the absorption tower; in, The condenser's inlet is connected to the gas phase outlet of the polyether reactor; the condenser's non-condensable gas outlet is connected to the inlet pipeline of the absorption tower; a pressure controller and a positive pressure valve are installed on this pipeline, and a bypass pipeline is also installed between the pressure controller and the positive pressure valve, connecting to the inlet of the absorption tower; a vacuum valve and a vacuum system are sequentially installed on the bypass pipeline; thereby, the non-condensable gas in the condenser is sent into the absorption tower by controlling the positive pressure valve, vacuum valve, and vacuum system through the pressure controller; the purification tower's inlet is connected to the material outlet of the polyether reactor's bottom, and the purification tower's top exhaust port is connected to the inlet of the absorption tower.

2. The apparatus according to claim 1, characterized in that, The condenser is also provided with a liquid phase outlet for discharging condensate; and / or, The absorption tower has three inlets: a first inlet, a second inlet, and a third inlet. A pipeline equipped with a pressure controller and a positive pressure valve is connected to the first inlet. The positive pressure valve is located at the first inlet. A bypass pipeline is connected to the second inlet. A vacuum valve and a vacuum system are located at the second inlet. The exhaust port at the top of the refining tower is connected to the third inlet of the absorption tower. And / or, The absorption tower is provided with a waste gas outlet and an absorbent inlet at the top, and a waste liquid outlet at the bottom; and / or, The refining tower also has a polyether product outlet for discharging polyether products.

3. The apparatus according to claim 2, characterized in that, The device further includes a condensate collection tank, the inlet of which is connected to the liquid phase outlet of the condenser; and / or, The top of the condensate collection tank is provided with an exhaust port, which is connected to the pipeline at the non-condensable gas outlet of the condenser; and / or, The bottom of the condensate collection tank is provided with a discharge port for discharging the liquid phase containing ethylene oxide; and / or, The condensate collection tank is equipped with an internal coil.

4. The apparatus according to claim 1, characterized in that, It also includes water and a reactor, the inlets of which are connected to the waste liquid outlet of the absorption tower, and the outlets of which are connected to the absorbent inlet of the absorption tower; and / or, The water and reactor are filled with a catalyst; preferably, the catalyst is a molecular sieve carboxylic acid catalyst.

5. The apparatus according to claim 1, characterized in that, The refining tower is a multi-stage stripping refining tower; preferably, the stripping steam used in the multi-stage stripping refining tower is one or a combination of nitrogen and low-pressure water vapor.

6. The apparatus according to claim 2, characterized in that, A temperature controller is provided at the liquid phase outlet of the condenser.

7. A method for purifying polyether using the apparatus according to claims 1 to 6, the method comprising the following steps: The gaseous material discharged from the polyether reactor is condensed and separated into condensate and non-condensable gas. The condensate is sent out, and the non-condensable gas enters the absorption tower under the control of the pressure controller. The liquid material in the polyether reactor is purified and separated into gaseous material and polyether product. The gaseous material enters the absorption tower, and the polyether product is sent out.

8. The method according to claim 7, characterized in that, The pressure controller controls positive pressure valves, vacuum valves, and vacuum systems as follows: When P / P 平衡 >1. The pressure controller controls the positive pressure valve to open and the vacuum valve and vacuum system to close, allowing gaseous materials to enter the absorption tower through the positive pressure valve; When P / P 平衡 ≤1, the pressure controller controls the positive pressure valve to close, and the vacuum valve and vacuum system to open, so that the gaseous material enters the absorption tower through the vacuum valve and vacuum system; P represents the pressure detected online by the pressure controller. 平衡 This is the balancing pressure of the device. Preferably, P 平衡 The range is 0–5 kPaG, preferably 0–3 kPaG.

9. The method according to claim 8, characterized in that, The method for controlling the condensate temperature at the liquid outlet of the condenser is as follows: When P / P 平衡 >1. The liquid phase outlet temperature of the condenser is controlled to be greater than 0°C and less than or equal to 5°C; When P / P 平衡 ≤1, the liquid phase outlet temperature of the condenser is controlled to be -10 to 0℃.

10. The method according to claim 9, characterized in that, The temperature inside the condensate collection tank is 3-5°C lower than the liquid phase outlet of the condenser.

11. The method according to claim 7, characterized in that, The mass ratio of liquid material to stripping steam introduced into the refining tower is 10–30; preferably 15–20.

12. The method according to claim 7, characterized in that, The weight ratio between the absorbent liquid and the gas entering the absorption tower is controlled as follows: When P / P 平衡 >1, the weight ratio of absorbent to gas is 20-30; When P / P 平衡 ≤1, the weight ratio of absorbent to gas is 10 to 20.

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