Method for treating materials containing propylene oxide and propylene, application and device thereof, and method for recovering propylene oxide tail gas

Abstract

The present invention provides a method for treating materials containing propylene oxide and propylene, and its application, a method for recovering propylene oxide tail gas, and a device for treating materials containing propylene oxide and propylene. The method comprises: a) sending the materials containing propylene oxide and propylene into a high-pressure propylene recovery tower for separation, extracting and recovering most of the propylene from the tower top, and extracting from the tower bottom and sending it to a propylene separation unit to separate the residual propylene; b) sending the tower bottom material after the propylene separation unit separates the residual propylene into a crude PO tower, separating most of the propylene oxide from the crude PO tower top, and using the propylene condensate recovered from the tower top of the high-pressure propylene recovery tower as a refrigerant for the crude PO tower tail gas; c) the crude PO tower bottom liquid enters post-treatment to separate and recover the residual propylene oxide. The method and device of the present invention have low energy consumption and high separation efficiency for recovering propylene mixed gas.

Description

Technical Field

[0001] The invention relates to a method for treating a material containing propylene oxide and propylene and an application of the method in recovering propylene oxide tail gas, a method for recovering propylene oxide tail gas and a device for treating a material containing propylene oxide and propylene. Background Art

[0002] Propylene oxide (PO) is an important organic chemical raw material and the second largest propylene derivative after polypropylene. Its largest use is to make polyols (polyethers) and then polyurethane. In the United States and Western Europe, this use accounts for more than 60% and 70% respectively. Propylene oxide is used to make non-ionic surfactants and propylene alcohol, propylene glycol, isopropanolamine, propionaldehyde, synthetic glycerin, organic acids, synthetic resins, foam plastics, plasticizers, emulsifiers, wetting agents, detergents, fungicides, fumigants, etc. Fine chemicals derived from propylene oxide are used in almost all industrial sectors and daily life.

[0003] The main process of producing propylene oxide by the peroxide method is the manufacture of organic hydrogen peroxide, and propylene is oxidized by peroxide. At present, the co-production of propylene oxide with styrene (PO / SM), the co-production of propylene oxide with methyl tert-butyl ether (PO / MTBE), the direct oxidation of hydrogen peroxide (HPPO method), and the hydrogen peroxide cumene method (CHP method) are the research hotspots of new processes for producing propylene oxide at home and abroad. Whether it is the production of organic hydrogen peroxide or the transfer of oxygen from peroxide to propylene molecules in the presence of a catalyst, this reaction is a liquid phase reaction. In addition to the main product propylene oxide, this method also has a co-product. Currently, the ethylbenzene Hakon method and the isobutane Hakon method have been industrialized. The ethylbenzene Hakon method uses ethylbenzene as a raw material to produce ethylbenzene hydroperoxide through oxidation. Under the action of a catalyst such as copper cyclohexane, propylene is epoxidized to obtain propylene oxide and α-phenylethanol at the same time, which can be dehydrated to obtain styrene. The reaction temperature of ethylbenzene oxidation is 130-150℃, the pressure is 0.07-0.14MPa, and the selectivity of ethylbenzene hydroperoxide is 90%. The epoxidation temperature is 50-120℃, and the pressure is normal pressure-0.864MPa. For example, a mixture of 14% ethylbenzene hydroperoxide, 35% propylene, 50% ethylbenzene, and 1% α-phenylethanol (mass fraction) is added with 0.4% manganese cyclohexane acid-sodium cyclohexane acid (nMo / nNa=2, molar ratio) as a catalyst, and reacted at 100℃ for 1.5h, the conversion rate of ethylbenzene hydroperoxide is 99%, and the selectivity of propylene oxide is 78%. The reaction product can be distilled to obtain the finished propylene oxide, and α-phenylethanol is dehydrated at 250-280℃ using TiO3-Al2O3 as a catalyst in the dehydration reactor, and 100% is converted into styrene, and its selectivity is 92%. The characteristics of this method are low cost, economic rationality, less three wastes, and co-production of styrene. The isobutane Hakon process uses isobutane as the raw material, and then reacts with propylene through the oxidant tert-butyl hydroperoxide to obtain propylene oxide and tert-butyl alcohol. The process is similar to the ethylbenzene Hakon process. The preparation of tert-butyl hydroperoxide is at 100-110°C without a catalyst. Usually tert-butyl hydroperoxide is used as an initiator. The reaction conditions for propylene epoxidation are a reaction temperature of 121°C and a pressure of 4.1MPa. It is carried out in the presence of a molybdenum catalyst, the reaction time is 0.5h, the yield of propylene oxide is 88% (calculated as peroxide), and the selectivity is 81%. This method can co-produce tert-butyl alcohol with a yield of about 60%. The reaction equation is (CH3)2CHCH3+O2→(CH3)3COOH+(CH3)3COH.

[0004] At present, the four processes for producing PO account for 43.2%, 48.2%, 4.9% and 3.7% of the global production capacity respectively. Among the co-oxidation methods, the PO / SM co-oxidation method accounts for 32.7%, and the PO / TBA co-oxidation method accounts for 15.5%. At present, the development trend of PO production technology development is mainly focused on the research and development of new green and environmentally friendly processes and the improvement of traditional PO production technology. Due to technical reasons, most of my country's PO devices currently adopt the chlorohydrin method for production. Only CNOOC-Shell and Zhenhai Refining and Chemical-Lyondell use the PO / SM co-oxidation method for production, and Sinopec Changling Petrochemical uses the HPPO technology with independent intellectual property rights of Sinopec (Petroleum Research Institute) for production.

[0005] In the production process of propylene oxide, propylene recovery and recycling and propylene oxide separation are involved. In the epoxidation reaction of olefins such as propylene, benzyl alcohol or α, α-dimethylbenzyl alcohol (DMBA) undergoes a dehydration reaction to produce styrene or α-methylstyrene (AMS) and water. In the epoxidation reactor, a small amount of DMBA will decompose into AMS and water, and AMS will be hydrogenated and converted into isopropylbenzene in the subsequent DMBA hydrogenolysis reactor.

[0006]

[0007] CHP condenses with DMBA to form dicumyl peroxide and water. During the epoxidation reaction and distillation process, a trace amount of CHP will condense with DMBA to form dicumyl peroxide. The formation of this substance affects the effective utilization rate of CHP and increases the consumption of isopropylbenzene.

[0008]

[0009] At the same time, during the propylene epoxidation reaction, a side reaction of generating organic acids will also occur. Propylene is oxidized into formaldehyde and acetaldehyde, and formaldehyde and acetaldehyde are further oxidized into formic acid and acetic acid.

[0010]

[0011] Propylene oxide is isomerizes to propionaldehyde, which is further oxidized to propionic acid.

[0012]

[0013] In the epoxidation reactor, in the presence of water and organic acid, PO and water undergo a hydrolysis reaction to generate propylene glycol, and propylene glycol undergoes a polymerization reaction to generate oligomers.

[0014]

[0015]

[0016] In the process of propylene separation and recovery, since propylene and water form a low-boiling azeotrope, the higher the pressure, the higher the water content in the azeotrope. After the top gas is condensed, propylene and water undergo liquid-liquid phase separation. If only ordinary sedimentation is used, the propylene recovered from the top of the tower will contain a small amount of water, which will be circulated to the epoxidation reactor, increasing the hydrolysis of propylene oxide. The presence of water, phenol and propylene glycol will promote the formation of PO polymers, which is also the main by-product affecting PO selectivity. The formation of PO oligomers not only increases propylene consumption, but also reduces the activity of the catalyst due to its coverage on the catalyst surface. Reducing the water content in the material can significantly reduce the formation of PO oligomers.

[0017] In addition, in the process of separating propylene oxide, such as in the crude PO tower, if the propylene is separated thoroughly in the front stage, the propylene oxide content at the top of the tower will be ≥99.5%, and there will be almost no non-condensable gas, resulting in low pressure at the top of the tower. At 0°C, the corresponding PO saturated vapor pressure is -77kPaG, at 10°C, the corresponding PO saturated vapor pressure is -64kPaG, at 20°C, the corresponding PO saturated vapor pressure is -43kPaG, at 30°C, the corresponding PO saturated vapor pressure is -16kPaG, at 40°C, the corresponding PO saturated vapor pressure is 18kPaG, at 44°C, the corresponding PO saturated vapor pressure is 40kPaG, and at 50°C, the corresponding PO saturated vapor pressure is 70kPaG. In the absence of non-condensable gas and the ambient temperature is lower than 44°C, the pressure will be difficult to exceed 40kPaG, and the propylene oxide at the top of the tower will be difficult to recover by condensation using circulating cooling water.

[0018] In summer, the ambient temperature is around 30-40℃. Under direct sunlight without cover, the metal surface temperature of the device can reach 50℃ or even higher. The temperature of the PO reflux tank is high, and a large amount of propylene oxide will be vaporized into the non-condensable gas, causing propylene oxide loss. In addition, during periods of large temperature changes such as thunderstorms, windy weather, and large temperature differences between day and night, it will be difficult to control the pressure of the crude PO tower and the pressure will fluctuate greatly. Summary of the invention

[0019] The object of the present invention is to provide a method for treating materials containing propylene oxide and propylene with low energy consumption and high separation efficiency.

[0020] The inventor has found through research that during the separation process, the tail gas of the crude PO tower is condensed and recovered as a refrigerant by the condensed propylene recovered from the top of the high-pressure propylene recovery tower, so that the tail gas of propylene oxide can be recovered, and no additional propylene refrigerant recovery equipment and devices are needed, and the equipment investment is not increased. Further, a high-efficiency liquid-liquid separation component such as a fiber filter element is arranged in the reflux tank of the high-pressure propylene recovery tower to effectively separate free water in propylene, the top condenser of the crude PO tower adopts a rear regulating valve to control the heat exchange area of ​​the condenser and a heat bypass to control the pressure of the crude PO tower, and an aftercooler is added to the non-condensable gas pipeline after the reflux tank of the crude PO tower, and the pressure control valve after the aftercooler controls the pressure of the reflux tank. Finally, the tail gas recovery of propylene oxide and the stable control of the pressure of the crude PO tower can be achieved.

[0021] According to a first aspect of the present invention, the present invention provides a method for treating a material containing propylene oxide and propylene, the method comprising:

[0022] a) The material containing propylene oxide and propylene is sent to a high-pressure propylene recovery tower for separation, most of the propylene is extracted and recovered from the top of the tower, and the propylene extracted from the bottom of the tower is sent to a propylene separation unit to separate the residual propylene;

[0023] b) the bottom material after the propylene separation unit separates the residual propylene is sent to the crude PO tower, the crude PO tower separates most of the propylene oxide, and the propylene condensate recovered from the top of the high-pressure propylene recovery tower is used as a refrigerant to recover the crude PO tower tail gas;

[0024] c) The crude PO tower bottom liquid enters post-treatment to separate and recover the residual propylene oxide.

[0025] According to a second aspect of the present invention, the present invention provides application of the treatment method of the present invention in the recovery of propylene oxide tail gas.

[0026] According to a third aspect of the present invention, the present invention provides a method for recovering propylene oxide tail gas using the treatment method of the present invention, the method comprising:

[0027] a) The propylene epoxidation reaction product is sent to a high-pressure propylene recovery tower for separation, the top of the tower is taken out to recover most of the propylene, and the bottom of the tower is taken out and sent to a propylene separation unit to separate the residual propylene;

[0028] b) the bottom material after the propylene separation unit separates the residual propylene is sent to the crude PO tower, the crude PO tower separates most of the propylene oxide, and the tail gas of the crude PO tower is condensed and recovered as a refrigerant through the propylene condensate recovered from the top of the high-pressure propylene recovery tower;

[0029] c) The crude PO tower bottom liquid enters post-treatment to separate and recover the residual propylene oxide.

[0030] According to a fourth aspect of the present invention, the present invention provides an apparatus for treating a material containing propylene oxide and propylene, the apparatus comprising: a high-pressure propylene recovery tower, a low-pressure propylene recovery tower and a crude PO tower sequentially connected in series along the material flow direction;

[0031] The high-pressure propylene recovery tower is used to separate materials containing propylene oxide and propylene. Most of the propylene is extracted and recovered from the top of the tower, and the propylene extracted from the bottom of the tower is sent to the low-pressure propylene recovery tower to separate the residual propylene.

[0032] The bottom material after the residual propylene is separated by the low-pressure propylene recovery tower is sent to the crude PO tower, and the crude PO tower separates most of the propylene oxide. The propylene condensate recovered from the top of the high-pressure propylene recovery tower is used as a refrigerant to recover the tail gas of the crude PO tower;

[0033] Along the outflow direction of the discharge, a high-pressure propylene recovery tower top condenser and a high-pressure propylene recovery tower top reflux tank are sequentially arranged on the discharge pipeline of the high-pressure propylene recovery tower;

[0034] Along the discharge direction, a crude PO tower condenser, a crude PO tower reflux tank, and a crude PO tower aftercooler arranged on the discharge pipeline of the crude PO tower reflux tank are sequentially arranged on the discharge pipeline of the crude PO tower, and the cooling medium inlets of the crude PO tower condenser and the crude PO tower aftercooler are connected to the propylene outlet of the reflux tank at the top of the high-pressure propylene recovery tower.

[0035] Through the above technical solution, the recovery of propylene oxide tail gas and the stable control of crude PO tower pressure can be achieved without adding propylene refrigerant recovery equipment and devices and increasing equipment investment.

[0036] In the present invention, the propylene recovered from the top of the high-pressure propylene recovery tower is pressurized by a top reflux pump and used as a cooling medium for a crude PO tower top aftercooler to recover the propylene oxide tail gas from the top of the crude PO tower, thereby saving a set of chilled water systems and reducing device investment. At the same time, the propylene oxide tail gas can be recovered by using it as a cooling medium. The propylene heated and gasified or partially gasified by the tail gas is returned to the high-pressure propylene recovery tower, and the heat absorbed by the gasification of propylene is fully utilized, thereby avoiding the introduction of cooling media such as chilled water from outside the boundary, which increases the long-distance pipeline investment and transportation costs. The present invention utilizes the recovered low-temperature propylene to circulate in the device.

[0037] In the present invention, the propylene oxide tail gas recovery and crude PO tower pressure control method are preferably provided, and the high-pressure propylene recovery tower recovers propylene through ordinary sedimentation separation in a reflux tank, preferably firstly through a reflux tank for water separation, and the liquid phase after water separation then enters a high-efficiency liquid-liquid separation device such as a fiber filter element, a filler, etc. to remove residual free water and then circulates to the propylene epoxidation reaction unit. By adopting a high-efficiency liquid-liquid separation device, the water in the liquid phase can be removed to a value close to the theoretical calculated value.

[0038] In the present invention, the propylene oxide tail gas recovery and crude PO tower pressure control method are preferably provided, and the crude PO tower top pressure is controlled by the condenser post-regulating valve and the hot bypass. Since the crude PO tower feed is separated and recovered in the process of light components such as propylene in the previous process, the light components may be mostly or completely separated, and the light component content entering the crude PO tower top is extremely low or zero except for propylene oxide. The reflux tank pressure is the same or similar to the saturated vapor pressure of propylene oxide at the corresponding temperature. In the case of no cold or heat preservation measures for the reflux tank, the reflux tank temperature is greatly affected by the ambient temperature, and the pressure fluctuates greatly, which is not conducive to the control of the distillation tower. The combination of the condenser post-regulating valve and the hot bypass control can effectively solve the crude PO tower pressure control problem. Since the propylene oxide corresponds to the PO saturated vapor pressure of 18kPaG at 40°C, it is preferred to keep the hot bypass gas pipeline and the reflux tank cold at the same time. In addition, the pressure drop of the hot bypass regulating valve is close to the sum of the pressure drop of the condenser and its post-regulating valve, otherwise it will lead to control difficulties.

[0039] The present invention preferably has an aftercooler. Since the saturated vapor pressure of PO corresponding to propylene oxide at 40°C is 18 kPaG, the non-condensable gas pipeline of the crude PO tower top reflux tank is provided with an aftercooler. The pressure of the reflux tank is controlled by the aftercooler pressure control valve. The aftercooler uses chilled water or propylene recovered from the top of the high-pressure propylene recovery tower as a cooling medium. After propylene absorbs heat and gasifies or partially gasifies, it returns to the high-pressure propylene recovery tower as a feed. This has the advantages of high propylene oxide recovery efficiency and low investment.

[0040] The present invention utilizes a high-pressure propylene recovery tower to recover propylene (32-38° C.) as a refrigerant to replace high-grade cooling medium chilled water, thereby realizing propylene oxide tail gas recovery. The following table shows the vaporization latent heat of propylene at different temperatures.

[0041] Latent heat of vaporization of propylene at different temperatures

[0042] Temperature / ℃ -180 -160 -140 -120 -100 -80 -60 Latent heat of vaporization / kJ / mol 23.664 22.994 22.290 21.549 20.762 19.921 19.016 Temperature / ℃ -40 -20 0 20 40 60 80 Latent heat of vaporization / kJ / mol 18.032 16.952 15.742 14.356 12.698 10.567 7.264

[0043] As can be seen from the table above, the latent heat of vaporization of propylene is relatively large, and as the temperature rises, the latent heat of vaporization of propylene continues to decrease. This is because the higher the temperature, the more intense the thermal motion between liquid propylene molecules, the smaller the mutual force, and the less heat is needed for the propylene molecules in the liquid phase to break free into the gas phase, so the latent heat of vaporization is smaller.

[0044] In the present invention, in a preferred embodiment, the crude PO tower top pressure is controlled by a post-condenser regulating valve and a heat bypass, thereby achieving stable pressure control of the crude PO tower in the absence of non-condensable gas.

[0045] The present invention is described in detail below in conjunction with the accompanying drawings, but it should be pointed out that the protection scope of the present invention is not limited thereto but is determined by the claims in the appendix.

[0046] 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 conventionally understood by those skilled in the art. In the event of a conflict, the definition in this specification shall prevail.

[0047] When this specification uses the prefix "well-known to those skilled in the art", "prior art" or similar terms to introduce materials, substances, methods, steps, devices or components, etc., the objects introduced by the prefix cover those commonly used in the art when this application is filed, but also include those that are not commonly used at present but will become recognized in the art as being suitable for similar purposes. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 It is a schematic diagram of a process according to a preferred embodiment of the present invention.

[0049] Description of Reference Numerals

[0050] A-High-pressure propylene recovery tower

[0051] B-High-pressure propylene recovery tower top condenser

[0052] C-High-pressure propylene recovery tower top reflux tank

[0053] D-Low Pressure Propylene Recovery Tower

[0054] E-Crude PO Tower

[0055] F-Crude PO Tower Reflux Tank

[0056] G-Crude PO Tower Aftercooler

[0057] H-Crude PO Tower Condenser DETAILED DESCRIPTION

[0058] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0059] Unless otherwise specified, all percentages, parts, ratios, etc. mentioned in this specification are based on weight, unless the weight basis does not conform to the common understanding of those skilled in the art.

[0060] Unless otherwise specified, all pressures mentioned in this specification are absolute pressures.

[0061] The present invention provides a method for treating a material containing propylene oxide and propylene, the method comprising:

[0062] a) The material containing propylene oxide and propylene is sent to a high-pressure propylene recovery tower for separation, most of the propylene is extracted and recovered from the top of the tower, and the propylene extracted from the bottom of the tower is sent to a propylene separation unit to separate the residual propylene;

[0063] b) the bottom material after the residual propylene is separated by the propylene separation unit is sent to a crude PO tower, most of the propylene oxide is separated at the top of the crude PO tower, and the propylene condensate recovered at the top of the high-pressure propylene recovery tower is used as a refrigerant to recover the tail gas of the crude PO tower;

[0064] c) The crude PO tower bottom liquid enters post-treatment to separate and recover the residual propylene oxide.

[0065] In the present invention, the propylene recovered at the top of the high-pressure propylene recovery tower is pressurized and used as a cooling medium for a crude PO tower top aftercooler to recover the propylene oxide tail gas at the top of the crude PO tower, thereby saving a set of chilled water systems and reducing device investment.

[0066] According to a preferred embodiment of the present invention, the 40-50° C. non-condensable gas of the crude PO tower tail gas is condensed and recovered by using the condensed propylene recovered from the top of the high-pressure propylene recovery tower as a refrigerant.

[0067] According to a preferred embodiment of the present invention, the step of recovering propylene in the high-pressure propylene recovery tower comprises: condensing the gas produced from the top of the high-pressure propylene recovery tower through a condenser and sending it into a reflux tank equipped with a liquid-liquid separation for sedimentation and liquid-liquid separation, producing water from the bottom of the reflux tank and condensing propylene, and producing non-condensable gas from the top of the reflux tank to the flare; preferably, the condensed propylene is divided into at least three streams, one of which is returned to the high-pressure propylene recovery tower as reflux, one is used as a refrigerant to condense and recover the crude PO tower tail gas, another is returned to the feed port of the high-pressure propylene recovery tower A as a circulating stream, and another stream can be produced.

[0068] According to a preferred embodiment of the present invention, preferably, the temperature at the condenser outlet is 30-50°C.

[0069] According to a preferred embodiment of the present invention, the crude PO tower top pressure is controlled by a post-condenser regulating valve and a thermal bypass. In the present invention, the propylene oxide tail gas recovery and crude PO tower pressure control method is preferably provided, and the crude PO tower top pressure is controlled by a post-condenser regulating valve and a thermal bypass. Since the crude PO tower feed is separated and recovered in the process of light components such as propylene in the previous process, the light components may be mostly or completely separated, and the light component content entering the crude PO tower top is extremely low or zero except for propylene oxide. The reflux tank pressure is the same or similar to the saturated vapor pressure of propylene oxide at the corresponding temperature. In the absence of cold or heat preservation measures for the reflux tank, the reflux tank temperature is greatly affected by the ambient temperature, and the pressure fluctuates greatly, which is not conducive to the control of the distillation tower. The combination of the post-condenser regulating valve and the thermal bypass control can effectively solve the crude PO tower pressure control problem. Since the propylene oxide corresponds to the PO saturated vapor pressure of 18kPaG at 40°C, it is preferred to keep the hot bypass gas pipeline and the reflux tank cold at the same time. In addition, the pressure drop of the hot bypass regulating valve should be close to the sum of the pressure drops of the condenser and its subsequent regulating valves, otherwise it will lead to control difficulties.

[0070] According to a preferred embodiment of the present invention, a tower top reflux tank is provided at the top of the crude PO tower, an aftercooler is provided at the non-condensable gas pipeline of the tower top reflux tank, and the pressure of the reflux tank is controlled by a pressure control valve after the aftercooler. The present invention preferably provides an aftercooler. Since propylene oxide corresponds to a PO saturated vapor pressure of 18 kPaG at 40°C, an aftercooler is provided at the non-condensable gas pipeline of the tower top reflux tank of the crude PO tower, and the pressure of the reflux tank is controlled by a pressure control valve after the aftercooler. The aftercooler uses chilled water or high-pressure propylene recovery tower top to recover propylene as a cooling medium, and the propylene endothermic part is vaporized and returns to the high-pressure propylene recovery tower as a feed.

[0071] According to a preferred embodiment of the present invention, the propylene recovered from the top of the high-pressure propylene recovery tower is pressurized by a top reflux pump and used as a cooling medium for the crude PO tower top tail gas to recover the crude PO tower top propylene oxide tail gas.

[0072] According to a preferred embodiment of the present invention, the method further comprises: circulating the refrigerant propylene condensate in step b) to a high-pressure propylene recovery tower as feed after condensation.

[0073] According to a preferred embodiment of the present invention, the temperature of the propylene condensate is 32-38°C.

[0074] According to a preferred embodiment of the present invention, the operating pressure of the high-pressure propylene recovery tower is 1.60 to 2.20 MPaG, preferably 1.65 to 2.10 MPaG.

[0075] According to a preferred embodiment of the present invention, the top temperature of the high-pressure propylene recovery tower is 40-60°C, preferably 45-55°C.

[0076] According to a preferred embodiment of the present invention, the operating pressure of the crude PO tower is 0.01-0.10 MPaG, preferably 0.02-0.06 MPaG.

[0077] According to a preferred embodiment of the present invention, the crude PO tower top temperature is 38-48°C, preferably 40-46°C.

[0078] According to a preferred embodiment of the present invention, the crude PO tower bottom temperature is 150-180°C, preferably 155-179°C.

[0079] According to a preferred embodiment of the present invention, the propylene oxide content in the crude PO tower bottom is controlled at 0.2 to 2.0% by mass, preferably 0.5 to 1.8% by mass.

[0080] According to a preferred embodiment of the present invention, the propylene separation unit is a low-pressure propylene recovery tower, and the operating conditions of the low-pressure propylene recovery tower can be conventionally selected and will not be described in detail herein.

[0081] According to a preferred embodiment of the present invention, the material containing propylene oxide and propylene is a propylene epoxidation reaction product.

[0082] The treatment method of the present invention is particularly suitable for application in the recovery of propylene oxide tail gas.

[0083] The present invention provides a method for recovering propylene oxide tail gas by using the treatment method of the present invention, the method comprising:

[0084] a) The propylene epoxidation reaction product is sent to a high-pressure propylene recovery tower for separation, the top of the tower is taken out to recover most of the propylene, and the bottom of the tower is taken out and sent to a propylene separation unit to separate the residual propylene;

[0085] b) the bottom material after the residual propylene is separated by the propylene separation unit is sent to the crude PO tower, most of the propylene oxide is separated at the top of the crude PO tower, and the tail gas of the crude PO tower is condensed and recovered as a refrigerant through the propylene condensate recovered at the top of the high-pressure propylene recovery tower;

[0086] c) The crude PO tower bottom liquid enters post-treatment to separate and recover the residual propylene oxide.

[0087] In the present invention, the propylene recovered at the top of the high-pressure propylene recovery tower is pressurized and used as a cooling medium for a crude PO tower top aftercooler to recover the propylene oxide tail gas at the top of the crude PO tower, thereby saving a set of chilled water systems and reducing device investment.

[0088] The present invention provides a device for treating materials containing propylene oxide and propylene, the device comprising: a high-pressure propylene recovery tower A, a low-pressure propylene recovery tower D and a crude PO tower E which are sequentially connected in series along the material flow direction;

[0089] The high-pressure propylene recovery tower A is used to separate materials containing propylene oxide and propylene. Most of the propylene is extracted and recovered from the top of the tower, and the bottom of the tower is extracted and sent to the low-pressure propylene recovery tower D to separate the residual propylene.

[0090] The bottom material after the residual propylene is separated by the low-pressure propylene recovery tower D is sent to the crude PO tower E, and most of the propylene oxide is separated at the top of the crude PO tower. The tail gas of the crude PO tower is condensed and recovered as a refrigerant through the propylene condensate recovered at the top of the high-pressure propylene recovery tower A;

[0091] Along the discharge direction, a high-pressure propylene recovery tower top condenser B and a high-pressure propylene recovery tower top reflux tank C are sequentially arranged on the discharge pipeline of the high-pressure propylene recovery tower A;

[0092] Along the discharge direction, a crude PO tower condenser H, a crude PO tower reflux tank F, and a crude PO tower aftercooler G arranged on the discharge pipeline of the crude PO tower reflux tank F are sequentially arranged on the discharge pipeline of the crude PO tower E, and the cooling medium inlets of the crude PO tower condenser H and the crude PO tower aftercooler G are connected to the propylene outlet of the reflux tank C at the top of the high-pressure propylene recovery tower.

[0093] According to a preferred embodiment of the present invention, a liquid-liquid separation unit is provided in the top reflux tank C of the high-pressure propylene recovery tower, and the liquid-liquid separation unit is one or more of a fiber filter element, a metal filter element, a non-metallic fiber felt, and metal and non-metallic blades.

[0094] According to a preferred embodiment of the present invention, a regulating valve is provided on the discharge pipeline of the crude PO tower condenser H, and the crude PO tower top pressure is controlled by the regulating valve and the heat bypass of the crude PO tower condenser H. According to a preferred embodiment of the present invention, the high-pressure propylene recovery tower A at least comprises a gas inlet to be treated, a tower top outlet, a tower bottom outlet and a reflux inlet.

[0095] According to a preferred embodiment of the present invention, the high-pressure propylene recovery tower top reflux tank C at least includes a feed inlet, a non-condensable gas outlet, a free water outlet, and a condensed propylene outlet. Preferably, the condensed propylene outlet is connected to at least three discharge pipelines, one of which is connected to the reflux inlet of the high-pressure propylene recovery tower A, and one is connected to the cooling medium inlet of the crude PO tower aftercooler G and the crude PO tower condenser H.

[0096] According to a preferred embodiment of the present invention, the crude PO tower E at least comprises a feed inlet, a tower top outlet, a tower bottom outlet and a reflux inlet.

[0097] According to a preferred embodiment of the present invention, the crude PO tower reflux tank F comprises at least two feed ports, a non-condensable gas outlet, and a cold liquid outlet, and the non-condensable gas outlet is connected to the gas feed port of the crude PO tower aftercooler G.

[0098] According to a preferred embodiment of the present invention, the crude PO tower aftercooler G comprises at least a gas feed inlet, a cooling medium inlet, a tail gas outlet and a cooling medium outlet. Preferably, the cooling medium outlet of the crude PO tower aftercooler G is connected to the inlet of the high-pressure propylene recovery tower A for the gas to be treated.

[0099] According to a preferred embodiment of the present invention, the present invention comprises:

[0100] a) the propylene epoxidation reaction product is sent to a high-pressure propylene recovery tower to separate most of the propylene, and the bottom of the tower is sent to a propylene separation unit such as a low-pressure propylene recovery tower to separate the residual propylene;

[0101] b) The bottom material after the propylene separation unit separates the residual propylene is sent to the crude PO tower, and most of the propylene oxide is separated at the top of the crude PO tower;

[0102] c) The crude PO tower bottom liquid enters post-treatment to separate and recover the residual propylene oxide.

[0103] According to the present invention, it is preferred that the high-pressure propylene recovery tower recovers propylene through ordinary sedimentation separation in a reflux tank, preferably firstly through a reflux tank for water separation, and the liquid phase after water separation then enters a high-efficiency liquid-liquid separation device such as a fiber filter element, a filler, etc. to remove residual free water and then circulates to the propylene epoxidation reaction unit. By using a high-efficiency liquid-liquid separation device, the water in the liquid phase can be removed to a value close to the theoretical calculated value.

[0104] According to the present invention, the propylene oxide tail gas recovery and crude PO tower pressure control method, the crude PO tower top pressure is controlled by the condenser post-regulating valve and the hot bypass. Since the crude PO tower feed is separated and recovered in the process of light components such as propylene in the previous process, the light components may be mostly or completely separated, and the light component content entering the crude PO tower top is extremely low or zero except for propylene oxide. The reflux tank pressure is the same or similar to the saturated vapor pressure of propylene oxide at the corresponding temperature. In the case of no cold or heat preservation measures for the reflux tank, the reflux tank temperature is greatly affected by the ambient temperature, and the pressure fluctuates greatly, which is not conducive to the control of the distillation tower. The combination of the condenser post-regulating valve and the hot bypass control can effectively solve the distillation tower pressure control problem. Since the propylene oxide corresponds to the PO saturated vapor pressure of 18kPaG at 40°C, it is preferred to keep the hot bypass gas pipeline and the reflux tank cold at the same time. In addition, the pressure drop of the hot bypass regulating valve is close to the sum of the pressure drop of the condenser and its post-regulating valve, otherwise it will lead to control difficulties.

[0105] Since the saturated vapor pressure of PO corresponding to propylene oxide at 40°C is 18kPaG, an aftercooler is provided for the non-condensable gas pipeline of the crude PO tower top reflux tank, and the pressure of the reflux tank is controlled by a pressure control valve after the aftercooler. The aftercooler uses chilled water or propylene recovered from the top of the high-pressure propylene recovery tower as a cooling medium, and the heat-absorbing part of the propylene is vaporized and returned to the high-pressure propylene recovery tower as a feed.

[0106] According to the present invention, the propylene recovered from the top of the high-pressure propylene recovery tower is preferably pressurized and used as the cooling medium of the crude PO tower top aftercooler to recover the propylene oxide tail gas from the crude PO tower top, thereby saving a set of chilled water system and reducing device investment.

[0107] According to the present invention, the propylene in the cooling medium of the crude PO tower top aftercooler is circulated to the high-pressure propylene recovery tower as feed.

[0108] According to the present invention, the operating pressure of the high-pressure propylene recovery tower is 1.60-2.20 MPaG, preferably 1.80-2.10 MPaG.

[0109] According to the present invention, the operating pressure of the crude PO tower is 0.01-0.10 MPaG, preferably 0.02-0.06 MPaG.

[0110] According to the present invention, the crude PO tower bottom temperature is 160-180°C, preferably 165-175°C.

[0111] According to the present invention, the propylene oxide content in the crude PO tower bottom is controlled at 0.2-2.0%, preferably 0.5-1.2%.

[0112] According to the present invention, a high-pressure propylene recovery tower is used to recover propylene (32-38° C.) as a refrigerant to replace high-grade cooling medium chilled water.

[0113] According to a preferred embodiment of the present invention, the method of the present invention comprises the following steps: the propylene epoxidation reaction product 1 enters a high-pressure propylene recovery tower A, the tower top gas 3 enters a tower top condenser B, the condensed logistics 4 enters a propylene reflux tank C, the propylene reflux tank C is provided with a fiber filter element and other materials, the free water 6 in the propylene is enhanced and separated, the non-condensable gas 5 is flared, and the condensed propylene is divided into three streams, wherein a stream 8 is used as a reflux, a stream 9 is circulated to the propylene epoxidation unit, and a stream 7 is used as a cooling medium for a crude PO tower aftercooler, and the propylene 19 after heat exchange returns to the high-pressure recovery tower and is mixed with the feed 1 as a feed Material 2, high-pressure propylene recovery tower bottom liquid 11, enters the low-pressure propylene recovery tower to partially separate the residual propylene, and the bottom liquid 21 enters the crude PO tower E. The bottom of the tower is the bottom liquid 22 that separates most of the propylene oxide. The top gas 12 is divided into two paths, one path 13 enters the reflux tank F through the top condenser H, and the other path 14 enters the reflux tank F through the regulating valve heat bypass. The condensate 15 is divided into two parts, one part is used as reflux 16, and the other part is used as production 17 to go to the propylene oxide refining unit. The non-condensable gas 18 goes to the aftercooler G, and the condensate returns to the reflux tank F. The pressure of the reflux tank F is controlled by the pressure regulating valve 20 after the aftercooler G. The pressure of the crude PO tower is controlled by the regulating valve after the condenser H to control the heat exchange area of ​​the condenser H and the heat bypass control.

[0114] The raw material propylene epoxidation reaction product treated by the method of the present invention is a reaction solution obtained by the epoxidation reaction of an organic hydroperoxide and an olefin. The epoxidation reaction of an organic hydroperoxide and an olefin is disclosed in the prior art. Depending on the organic hydroperoxide, there can be a hydroperoxide isopropylbenzene method (CHP method) and a hydroperoxide ethylbenzene method (EBHP method). The alkylene oxide is propylene oxide, butylene oxide, or its isomers, preferably butylene oxide, and more preferably 1,2-butylene oxide. Taking the production of 1,2-butylene oxide as an example, the hydroperoxide isopropylbenzene method (CHP method) uses hydroperoxide isopropylbenzene (CHP) as an oxidant, and CHP epoxidizes 1-butene to obtain 1,2-butylene oxide and α,α-dimethylbenzyl alcohol, and α,α-dimethylbenzyl alcohol is hydrogenolyzed to generate isopropylbenzene, and isopropylbenzene is oxidized to generate CHP for recycling.

[0115] In the context of this specification, except for the contents explicitly described, any matters or items not mentioned are directly applicable to those known in the art without any changes. Moreover, any embodiment described herein can be freely combined with one or more other embodiments described herein, and the technical solutions or technical ideas formed thereby are regarded as part of the original disclosure or original record of the present invention, and should not be regarded as new contents not disclosed or anticipated herein, unless a person skilled in the art considers that the combination is obviously unreasonable.

[0116] The present invention will be further described below through specific implementation modes.

[0117] Example 1

[0118] like Figure 1 As shown, the propylene epoxidation reaction product 1 enters the high-pressure propylene recovery tower A, the tower top gas 3 enters the tower top condenser B, and the condensed logistics 4 enters the propylene reflux tank C. The propylene reflux tank C is provided with a fiber filter material to enhance the separation of free water 6 in the propylene. The non-condensable gas 5 goes to the flare. The condensed propylene is divided into three streams, one stream 8 is used as reflux, one stream 9 is circulated to the propylene epoxidation unit, and one stream 7 is used as a cooling medium for the crude PO tower aftercooler. After heat exchange, the propylene 19 returns to the high-pressure recovery tower and is mixed with the feed 1 as the feed 2. The high-pressure propylene recovery tower bottom liquid 11 , after entering the low-pressure propylene recovery tower to partially separate the residual propylene, the kettle liquid 21 enters the crude PO tower E, the tower kettle is the kettle liquid 22 that separates most of the propylene oxide, the top gas 12 is divided into two paths, one path 13 enters the reflux tank F through the top condenser H, and the other path 14 enters the reflux tank F through the regulating valve thermal bypass, the condensate 15 is divided into two parts, one part is used as reflux 16, and the other part is used as production 17 to go to the propylene oxide refining unit, the non-condensable gas 18 goes to the aftercooler G, and the condensate returns to the reflux tank F. The pressure of the reflux tank F is controlled by the regulating valve 20 after the aftercooler G. The pressure of the crude PO tower is controlled by the regulating valve after the condenser H to control the heat exchange area of ​​the condenser H and the thermal bypass control.

[0119] The operating pressure of the high-pressure propylene recovery tower is 1.67MPaG, and the tower top temperature is 45.8℃.

[0120] The operating conditions of the top condenser H include: the condenser outlet temperature is 40°C.

[0121] The operating pressure of the crude PO tower is 0.025 MPaG, the top temperature is 40°C, and the bottom temperature is 157°C.

[0122] The propylene oxide content in the crude PO tower bottom was controlled at 1.74 wt%.

[0123] Under the conditions that the crude PO tower feed does not contain light components such as propylene, and there is no non-condensable gas or very little non-condensable gas at the top of the tower, the crude PO tower pressure is stable and operates normally through the above control method.

[0124] The tail gas from the crude PO tower is recovered through propylene cooling medium, and the recovery rate of propylene oxide in the tail gas can reach 96.1%.

[0125] Example 2

[0126] As in Example 1, the operating pressure of the high-pressure propylene recovery tower is 1.84 MPaG, and the tower top temperature is 49.5°C.

[0127] The operating conditions of the top condenser include: condenser outlet temperature 36°C.

[0128] The operating pressure of the crude PO tower is 0.04MPaG, the top temperature is 44.5℃, and the bottom temperature is 169℃.

[0129] The propylene oxide content in the crude PO tower bottom was controlled at 1.38% by mass.

[0130] Under the conditions that the crude PO tower feed does not contain light components such as propylene, and there is no non-condensable gas or very little non-condensable gas at the top of the tower, the crude PO tower pressure is stable and operates normally through the above control method.

[0131] The tail gas from the crude PO tower is recovered through propylene cooling medium, and the recovery rate of propylene oxide in the tail gas can reach 97.0%.

[0132] Example 3

[0133] As in Example 1, the operating pressure of the high-pressure propylene recovery tower is 1.87 MPaG, and the tower top temperature is 50.5°C.

[0134] The operating conditions of the top condenser include: condenser outlet temperature 35°C.

[0135] The operating pressure of the crude PO tower is 0.04MPaG, the top temperature is 44.5℃, and the bottom temperature is 170℃.

[0136] The propylene oxide content in the crude PO tower bottom was controlled at 1.11% by mass.

[0137] Under the conditions that the crude PO tower feed does not contain light components such as propylene, and there is no non-condensable gas or very little non-condensable gas at the top of the tower, the crude PO tower pressure is stable and operates normally through the above control method.

[0138] The tail gas from the crude PO tower is recovered through propylene cooling medium, and the recovery rate of propylene oxide in the tail gas can reach 97.5%.

[0139] Example 4

[0140] As in Example 1, the operating pressure of the high-pressure propylene recovery tower is 1.94 MPaG, and the tower top temperature is 53.3°C.

[0141] The operating conditions of the top condenser include: condenser outlet temperature 35°C.

[0142] The operating pressure of the crude PO tower is 0.05MPaG, the top temperature is 45.5℃, and the bottom temperature is 170℃.

[0143] The propylene oxide content in the crude PO tower bottom was controlled at 1.37% by mass.

[0144] Under the conditions that the crude PO tower feed does not contain light components such as propylene, and there is no non-condensable gas or very little non-condensable gas at the top of the tower, the crude PO tower pressure is stable and operates normally through the above control method.

[0145] The tail gas from the crude PO tower is recovered through propylene cooling medium, and the recovery rate of propylene oxide in the tail gas can reach 97.5%.

[0146] Example 5

[0147] As in Example 1, the operating pressure of the high-pressure propylene recovery tower is 1.94 MPaG, and the tower top temperature is 53.3°C.

[0148] The operating conditions of the top condenser include: condenser outlet temperature 35°C.

[0149] The operating pressure of the crude PO tower is 0.041 MPaG, the top temperature is 44.5°C, and the bottom temperature is 181°C.

[0150] The propylene oxide content in the crude PO tower bottom was controlled at 0.34% by mass.

[0151] Under the conditions that the crude PO tower feed does not contain light components such as propylene, and there is no non-condensable gas or very little non-condensable gas at the top of the tower, the crude PO tower pressure is stable and operates normally through the above control method.

[0152] The tail gas from the crude PO tower is recovered through propylene cooling medium, and the recovery rate of propylene oxide in the tail gas can reach 97.5%.

[0153] Example 6

[0154] As in Example 1, the operating pressure of the high-pressure propylene recovery tower is 1.94 MPaG, and the tower top temperature is 53.3°C.

[0155] The operating conditions of the top condenser include: condenser outlet temperature 32°C.

[0156] The operating pressure of the crude PO tower is 0.043 MPaG, the top temperature is 44.8°C, and the bottom temperature is 178.6°C.

[0157] The propylene oxide content in the crude PO tower bottom is controlled at 0.50%.

[0158] Under the conditions that the crude PO tower feed does not contain light components such as propylene, and there is no non-condensable gas or very little non-condensable gas at the top of the tower, the crude PO tower pressure is stable and operates normally through the above control method.

[0159] The tail gas from the crude PO tower is recovered through propylene cooling medium, and the recovery rate of propylene oxide in the tail gas can reach 98.5%.

[0160] Example 7

[0161] As in Example 1, the operating pressure of the high-pressure propylene recovery tower is 1.94 MPaG, and the tower top temperature is 53.3°C.

[0162] The operating conditions of the top condenser include: condenser outlet temperature 34°C.

[0163] The operating pressure of the crude PO tower is 0.043 MPaG, the top temperature is 44.8°C, and the bottom temperature is 178.6°C.

[0164] The propylene oxide content in the crude PO tower bottom was controlled at 0.50% by mass.

[0165] Under the conditions that the crude PO tower feed contains 0.0063% propylene and the tower top contains a small amount of non-condensable gas, the tower pressure is stable and operates normally through the above control method.

[0166] The tail gas from the crude PO tower is recovered through propylene cooling medium, and the recovery rate of propylene oxide in the tail gas can reach 97.9%.

[0167] Comparative Example 1

[0168] Different from Example 1, when the feed does not contain components such as propylene and propane, when there is no thermal bypass for the tower top pressure control, and when the ambient temperature does not change or changes slightly, the pressure control can remain relatively stable. When the ambient temperature changes significantly, such as sudden heavy rain in summer, strong winds, large temperature difference between day and night, etc., the pressure of the distillation tower fluctuates greatly, and pressure control is difficult, making it difficult to operate stably to ensure product separation accuracy.

[0169] Comparative Example 2

[0170] Different from Example 1, the non-condensable gas stream 18 at the top of the reflux tank F is not cooled by the aftercooler G but directly goes to the flare, and the PO recovery rate of the crude PO tower is reduced by 0.04%.

[0171] Comparative Example 3

[0172] The difference from Example 1 is that the non-condensable gas flow 18 at the top of the reflux tank F is cooled by the aftercooler G, which is cooled by 10°C chilled water. The recovery rate of propylene oxide in the tail gas can reach 99.5%, and an additional chilled water circulation system is required.

[0173] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A method for treating a material containing propylene oxide and propylene, characterized in that: The method includes: a) The material containing propylene oxide and propylene is sent to a high-pressure propylene recovery tower for separation, most of the propylene is extracted and recovered from the top of the tower, and the propylene extracted from the bottom of the tower is sent to a propylene separation unit to separate the residual propylene; b) the bottom material after the residual propylene is separated by the propylene separation unit is sent to the crude PO tower, most of the propylene oxide is separated at the top of the crude PO tower, and the tail gas at the top of the crude PO tower is recovered as a refrigerant through the propylene condensate recovered at the top of the high-pressure propylene recovery tower; c) The crude PO tower bottom liquid enters post-treatment to separate and recover residual propylene oxide.

2. The processing method according to claim 1, wherein: The tail gas of the crude PO tower is condensed and recovered as a refrigerant by using the condensed propylene recovered from the top of the high-pressure propylene recovery tower.

3. The processing method according to claim 1 or 2, wherein: The steps of recovering propylene by the high-pressure propylene recovery tower include: condensing the gas extracted from the top of the high-pressure propylene recovery tower through a condenser and sending it to a reflux tank equipped with a liquid-liquid separation for liquid-liquid separation, extracting water from the bottom of the reflux tank, condensing propylene, and extracting non-condensable gas from the top of the reflux tank to a flare.

4. The processing method according to claim 3, wherein: The condensed propylene is divided into at least three streams, one of which is used as reflux liquid of a high-pressure propylene recovery tower, one is used as a refrigerant to condense and recover the crude PO tower tail gas, and the other is used as a circulating stream to return to the propylene epoxidation unit as a reaction raw material.

5. The processing method according to claim 3, wherein: The temperature at the condenser outlet is 30-50°C.

6. The processing method according to claim 1 or 2, wherein: The crude PO tower top pressure is controlled by a post-condenser regulating valve and a heat bypass.

7. The processing method according to claim 6, wherein: A tower top reflux tank is arranged at the top of the crude PO tower, an aftercooler is arranged on the non-condensable gas pipeline of the tower top reflux tank, and the pressure of the reflux tank is controlled by a pressure control valve after the aftercooler.

8. The processing method according to claim 1 or 2, wherein: The propylene recovered from the top of the high-pressure propylene recovery tower is pressurized by a top reflux pump and used as a cooling medium for the crude PO tower top tail gas to recover the crude PO tower top propylene oxide tail gas.

9. The processing method according to claim 1 or 2, wherein: The method further comprises: circulating the refrigerant propylene condensate in step b) to a high-pressure propylene recovery tower as feed after the condensation is completed.

10. The processing method according to claim 1 or 2, wherein: The operating pressure of the high-pressure propylene recovery tower is 1.60-2.20 MPaG; the tower top temperature is 40-60°C; and / or The crude PO tower operating pressure is 0.01-0.10 MPaG; and / or The crude PO tower top temperature is 38-48°C; and / or The crude PO tower kettle temperature is 150-180°C; and / or The propylene oxide content of the crude PO tower bottom is controlled to be 0.2-2.0% by mass; and / or The material containing propylene oxide and propylene is a propylene epoxidation reaction product.

11. The processing method according to claim 10, wherein: The operating pressure of the high-pressure propylene recovery tower is 1.65-2.10 MPaG; the tower top temperature is 45-55° C.; and / or The crude PO tower operating pressure is 0.02-0.06 MPaG; and / or The crude PO tower top temperature is 40-46°C; The crude PO tower bottom temperature is 155-179°C; and / or The propylene oxide content in the crude PO tower bottom is controlled to be 0.5-1.8% by mass.

12. The processing method according to claim 10, wherein: The propylene separation unit is a low-pressure propylene recovery tower.

13. Use of the treatment method according to any one of claims 1 to 12 in the recovery of propylene oxide tail gas.

14. A method for recovering propylene oxide tail gas using the treatment method according to any one of claims 1 to 12, the method comprising: a) The propylene epoxidation reaction product is sent to a high-pressure propylene recovery tower for separation, most of the propylene is taken out from the top of the tower and recovered, and the propylene taken out from the bottom of the tower is sent to a propylene separation unit to separate the residual propylene; b) the bottom material after the residual propylene is separated by the propylene separation unit is sent to the crude PO tower, most of the propylene oxide is separated at the top of the crude PO tower, and the propylene condensate recovered at the top of the high-pressure propylene recovery tower is used as a refrigerant to recover the tail gas of the crude PO tower; c) The crude PO tower bottom liquid enters post-treatment to separate and recover residual propylene oxide.

15. A device for treating materials containing propylene oxide and propylene, characterized in that: The device comprises: a high-pressure propylene recovery tower (A), a low-pressure propylene recovery tower (D) and a crude PO tower (E) which are sequentially connected in series along the material flow direction; The high-pressure propylene recovery tower (A) is used to separate materials containing propylene oxide and propylene, and most of the propylene is extracted and recovered from the top of the tower, and the bottom of the tower is extracted and sent to the low-pressure propylene recovery tower (D) to separate the residual propylene; The bottom material after the residual propylene is separated in the low-pressure propylene recovery tower (D) is sent to the crude PO tower (E), and most of the propylene oxide is separated at the top of the crude PO tower. The tail gas of the crude PO tower is condensed and recovered as a refrigerant through the propylene condensate recovered at the top of the high-pressure propylene recovery tower (A); Along the discharge direction, a high-pressure propylene recovery tower top condenser (B) and a high-pressure propylene recovery tower top reflux tank (C) are sequentially arranged on the discharge pipeline of the high-pressure propylene recovery tower (A); A crude PO tower condenser (H), a crude PO tower reflux tank (F), and a crude PO tower aftercooler (G) arranged on the discharge pipeline of the crude PO tower reflux tank (F) are sequentially arranged on the discharge pipeline of the crude PO tower (E) along the discharge flow direction, and the cooling medium inlets of the crude PO tower condenser (H) and the crude PO tower aftercooler (G) are connected to the propylene outlet of the reflux tank (C) at the top of the high-pressure propylene recovery tower.

16. The device according to claim 15, wherein: A liquid-liquid separation unit is arranged in the reflux tank (C) at the top of the high-pressure propylene recovery tower, and the liquid-liquid separation unit is one or more of a fiber filter element, a metal filter element, a non-metal fiber felt, a metal and a non-metal blade; and / or A regulating valve is provided on the discharge pipeline of the crude PO column condenser (H), and the crude PO column top pressure is controlled by the regulating valve and the heat bypass of the crude PO column condenser (H); and / or The high-pressure propylene recovery tower (A) at least comprises a to-be-treated gas inlet, a tower top outlet, a tower bottom outlet and a reflux inlet; The high-pressure propylene recovery tower top reflux tank (C) at least includes a feed inlet, a non-condensable gas outlet, a free water outlet, and a condensed propylene outlet; The crude PO tower (E) comprises at least a feed inlet, a tower top outlet, a tower bottom outlet and a reflux inlet; The crude PO tower reflux tank (F) comprises at least two feed inlets, a non-condensable gas outlet, and a cold liquid outlet, wherein the non-condensable gas outlet is connected to the gas feed inlet of the crude PO tower aftercooler (G); The crude PO tower aftercooler (G) comprises at least a gas feed inlet, a cooling medium inlet, a tail gas outlet and a cooling medium outlet.

17. The device according to claim 16, wherein: The condensed propylene outlet is connected to at least three discharge pipelines, one of which is connected to the reflux inlet of the high-pressure propylene recovery tower (A), and one is connected to the cooling medium inlet of the crude PO tower aftercooler (G) and the crude PO tower condenser (H); The cooling medium outlet of the crude PO tower aftercooler (G) is communicated with the inlet of the to-be-treated gas of the high-pressure propylene recovery tower (A).

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