Process for purifying a propylene mixture and process and apparatus for purifying recycled propylene

Abstract

The application discloses a purification method and device and method for purifying propylene mixed gas containing oxygen-containing organic matter, and the method comprises the following steps: absorbing the propylene mixed gas containing oxygen-containing organic matter by using an absorbent, carrying out gas-liquid separation on the gas phase after absorption, and entering the gas after the gas-liquid separation into secondary compression; and sending the absorption liquid containing oxygen-containing organic matter into an extraction tower to carry out extraction separation. The application can solve the problems that the existing technology has the problems of recovering propylene entraining components such as propylene oxide, formaldehyde, acetaldehyde and propionaldehyde, and the polymerization reaction occurs in the temperature rising process accompanied by compression and pressure rising, the performance of the compressor is affected, and the yield of propylene oxide is reduced. The method can be preferably used in the industrial production of propylene oxide.

Description

TECHNICAL FIELD

[0001] The present invention relates to a method for purifying a propylene mixed gas containing an oxygen-containing organic compound, a method for purifying recycled propylene using the purifying method of the present invention, and a device for purifying recycled propylene and a method for purifying recycled propylene. BACKGROUND

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

[0003] The main process of propylene oxide production by peroxide method is the manufacture of organic hydrogen peroxide, and the oxidation of propylene by peroxide. At present, the PO / SM, PO / MTBE, HPPO method, CHP method, and so on are the research hotspots of new process of propylene oxide production at home and abroad. The reaction is liquid phase reaction, whether it is the production of organic hydrogen peroxide or the transfer of peroxide oxygen to propylene molecule in the presence of catalyst. In addition to the main product propylene oxide, there are also by-products. The ethylbenzene cumene method and isobutane cumene method have been industrialized. The ethylbenzene cumene method uses ethylbenzene as raw material to produce ethylbenzene hydroperoxide, and then the propylene epoxidation reaction is carried out in the presence of copper naphthenate and other catalysts to obtain propylene oxide, and α-phenethyl alcohol is also obtained, which can be dehydrated to obtain styrene. The reaction temperature of ethylbenzene oxidation is 130-150, and the pressure is 0.07-0.14 MPa. The selectivity of ethylbenzene hydroperoxide is 90%, and the epoxidation temperature is 50-120 oxygen, and the pressure is normal pressure-0.864 MPa. For example, a mixture of ethylbenzene hydroperoxide 14%, propylene 35%, ethylbenzene 50%, α, phenethyl alcohol 1% (mass fraction) is added into 0.4% manganese naphthenate-sodium naphthenate (nMo / nNa=2, molar ratio) as catalyst, and the reaction is carried out at 100 for 1.5 h, the conversion rate of ethylbenzene hydroperoxide is 99%, and the selectivity of propylene oxide is 78%. The reaction product is treated by distillation to obtain propylene oxide product, and α, phenethyl alcohol is dehydrated in a dehydration reactor using TiO3-Al2O3 as catalyst at 250-280, which is converted into styrene at 100% with a selectivity of 92%. The characteristics of this method are low cost, economic rationality, less waste, and by-product styrene. The isobutane cumene method uses isobutane as raw material, and then reacts with tertiary butyl hydroperoxide to obtain propylene oxide and tertiary butanol, and the process is similar to the ethylbenzene cumene method. The preparation of tertiary butyl hydroperoxide is carried out at 100-110 without catalyst, and tertiary butyl hydroperoxide is usually used as initiator. The reaction conditions of propylene epoxidation are reaction temperature 121, pressure 4.1 MPa. In the presence of molybdenum catalyst, the reaction time is 0.5 h, the yield of propylene oxide is 88% (based on peroxide), and the selectivity is 81%. This method can also produce tertiary butanol with a yield of about 60%, and the reaction equation is (CH3)2CHCH3+O2→OCH3)3COOH+(CH3)3COH.

[0004] At present, the proportion of the four processes in the global production capacity of PO is 43.2%, 48.2%, 4.9% and 3.7% respectively. In the co-oxidation method, the PO / SM co-oxidation method is 32.7%, and the PO / TBA co-oxidation method is 15.5%. At present, the development trend of PO production technology development mainly focuses on the research and development of green and environmentally friendly new processes and the improvement of traditional PO production technology. Due to the influence of technical reasons, at present, the PO device in China basically adopts the hydrochlorination method for production, only CNOOC-Shell and Zhenhai Refining and Chemical-Lyondell use PO / SM co-oxidation method for production, and Sinopec Changling Petrochemical uses Sinopec (Shike Institute) self-owned intellectual property right HPPO technology for production.

[0005] In the production process of propylene oxide, propylene recovery and recycling and propylene oxide separation are involved. SUMMARY

[0006] The purpose of the present application is to solve the problem that the existing technology involves the recovery of propylene entraining components such as propylene oxide, formaldehyde, acetaldehyde and propionaldehyde, and the polymerization reaction occurs in the compression and pressure increase accompanied by the heating process, which affects the performance of the compressor and reduces the yield of propylene oxide; a purification method for propylene mixed gas containing oxygen-containing organic compounds, a method for purifying recycled propylene by using the purification method of the present application, a device for purifying recycled propylene and a method for purifying recycled propylene are provided.

[0007] The present inventors have found that the removal of oxygen-containing compound components such as propylene oxide, formaldehyde, acetaldehyde and propionaldehyde from propylene gas by water washing does not affect the subsequent purification of propylene gas, and can also inhibit the process defects caused by polymerization.

[0008] According to the first aspect of the present application, the present application provides a purification method for propylene mixed gas containing oxygen-containing organic compounds, which comprises: feeding the propylene mixed gas containing oxygen-containing organic compounds into an absorption tower to absorb the oxygen-containing organic compounds therein with an absorbent, and performing gas-liquid separation on the gas phase after absorption, and then feeding the gas after gas-liquid separation into secondary compression; feeding the absorption liquid containing oxygen-containing organic compounds into an extraction tower for extraction separation.

[0009] According to the second aspect of the present application, the present application provides a method for purifying recycled propylene by using the purification method of the present application, which comprises:

[0010] a) feeding the overhead gas of the low-pressure propylene recovery tower into an absorption tower to absorb with an absorbent, and performing gas-liquid separation on the gas phase after absorption, and then feeding the gas after gas-liquid separation into secondary compression;

[0011] b) feeding the absorption liquid containing water, propylene oxide, formaldehyde, acetaldehyde and propionaldehyde from the upper part of the extraction tower, and feeding the extractant from the lower part to extract and recover propylene oxide;

[0012] c) the upper organic phase of the extraction column is sent to the crude PO column as feed, and most of the lower aqueous phase of the extraction column is recycled to the absorption column as absorbing liquid, and a small part is discharged for post-treatment.

[0013] According to a third aspect of the present application, the present application provides a device for purifying recycled propylene, comprising:

[0014] an absorption column, a gas-liquid separation unit and a compression unit connected in series with the gas phase outlet of the absorption column;

[0015] an extraction column connected with the liquid phase outlet of the absorption column;

[0016] The absorption column is used for spray absorption of the overhead gas of the low-pressure propylene recovery column with desalted water; the gas-liquid separation unit is used for gas-liquid separation of the gas phase after absorption; and the compression unit is used for compression of the gas after gas-liquid separation.

[0017] The extraction column is used for extractive distillation of the absorbing liquid containing water, propylene oxide, formaldehyde, acetaldehyde and propionaldehyde.

[0018] According to a fourth aspect of the present application, the present application provides a method for purifying recycled propylene, comprising: feeding the high-pressure propylene column material into a first gas-liquid separation tank of a low-pressure propylene recovery column, feeding the gas phase from the lower part of the low-pressure propylene recovery column, feeding the liquid phase as reflux liquid from the top of the low-pressure propylene recovery column, condensing the overhead gas into a condenser, cooling the condensed liquid phase into a post-cooler of the low-pressure propylene recovery column, and then separating the gas-liquid mixture into a second gas-liquid separation tank, feeding the gas phase into a primary compressor, cooling the compressed gas phase into an inter-stage cooler, then separating the gas-liquid mixture into a third gas-liquid separation tank, feeding the overhead gas phase into an absorption column for absorption with absorbing liquid, feeding the absorbed gas into a fourth gas-liquid separation tank, then separating the gas-liquid mixture, feeding the gas phase into a secondary compressor, returning the gas after secondary compression to the high-pressure propylene recovery column, feeding the absorbing liquid into an extraction column for extraction recovery of propylene oxide with an extracting agent, combining the overhead organic phase of the extraction column and the column liquid of the low-pressure propylene recovery column, and then feeding the combined stream to a crude PO column, and feeding the column liquid to subsequent separation, and returning the liquid phase stream of the second gas-liquid separation tank, the liquid phase stream of the third gas-liquid separation tank, the column liquid stream of the extraction column, and the liquid phase stream of the fourth gas-liquid separation tank to the high-pressure propylene recovery column and / or the low-pressure propylene recovery column as feed.

[0019] The present application can solve the problem that in the prior art, components such as propylene, propylene oxide, formaldehyde, acetaldehyde and propionaldehyde are recovered, and in the process of compression and pressure increase accompanied by temperature increase, propylene oxide and aldehydes will all undergo polymerization to form polymers, affecting the performance of the compressor and reducing the yield of propylene oxide. The technical scheme of the present application is that after the overhead gas of the first-stage compression is absorbed, for example, sprayed, by an absorbent such as desalted water, the gas phase after absorption is subjected to gas-liquid separation, the gas after gas-liquid separation enters the second-stage compression, the absorbent liquid containing components such as propylene oxide, formaldehyde, acetaldehyde and propionaldehyde enters an extraction column to recover propylene oxide by isopropyl benzene extraction, the organic phase in the upper layer of the extraction column is sent to a crude PO column, and most of the water phase in the lower layer of the extraction column is recycled to the absorption column as absorbent liquid, and a small part is discharged for post-treatment.

[0020] By adopting the foregoing technical scheme of the present application, the propylene yield is greater than 99.9%, the content of propylene oxide entering the second-stage compressor is reduced to 4% or less, the purification process mainly adopts liquid-liquid extraction, the equipment investment is small, and the process energy consumption is almost not increased. The method of the present application can be well used in the industrial production of propylene oxide.

[0021] The present application is further described below through specific embodiments. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 It is a flow diagram of a preferred embodiment according to the present application.

[0023] Figure 2 It is a flow diagram of a comparative embodiment of the present application.

[0024] BRIEF DESCRIPTION OF REFERENCE NUMERALS:

[0025] A - first gas-liquid separation tank

[0026] B - low-pressure propylene recovery column

[0027] C - low-pressure propylene column overhead condenser

[0028] D - low-pressure propylene column overhead after-cooler

[0029] E - second gas-liquid separation tank

[0030] F - first-stage compressor

[0031] G - absorption column

[0032] H - extraction column

[0033] I - fourth gas-liquid separation tank

[0034] J - second-stage compressor

[0035] K - crude PO column

[0036] L-stage intercooler

[0037] M-third gas-liquid separation drum DETAILED DESCRIPTION

[0038] The endpoints of the ranges and any values described herein are not limited to the precise values stated. The endpoints of the ranges are provided as approximations of the range endpoints. Any numerical value, however, inherently contain certain errors necessarily resulting from the standard deviation found in their respective testing measurements. The endpoints of the ranges and any values are provided as approximations of the range endpoints. The endpoints of the ranges are provided as approximations of the range endpoints. In this manner, the numerical values are not to be construed as limited to the precise values set forth.

[0039] The application will be described in detail below with reference to the attached drawings, but it should be noted that the scope of the application is not limited to this, but is defined by the claims attached to the appendix.

[0040] All publications, patents, patent applications and other references mentioned in this specification are herein incorporated by reference. Unless otherwise defined, all technical and scientific terms used in this specification are to be taken as commonly understood terms within the technical field of the present application. In the case of conflict between a commonly understood term and a term specifically defined in this specification, the term specifically defined in this specification controls.

[0041] When the specification uses phrases such as "known to those skilled in the art", "prior art", or similar phrases to introduce material, substances, methods, steps, devices or components, etc., the objects introduced by these phrases encompass those that are conventionally used at the time of filing of the present application, but also those that are not yet conventionally used but will become generally recognized as suitable for similar purposes.

[0042] In the context of the present specification, unless explicitly stated otherwise, any matter or item not mentioned is directly applicable to those known in the art without any change. 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 considered to be part of the original disclosure or original description of the present application, and should not be considered as new content that has not been disclosed or anticipated herein, unless the combination is considered to be obviously unreasonable by those skilled in the art.

[0043] Unless explicitly stated otherwise, all percentages, parts, ratios, etc. mentioned in the specification are based on weight, unless it is not in line with the general understanding of those skilled in the art when based on weight.

[0044] Unless explicitly stated otherwise, all pressures mentioned in the specification are absolute pressures.

[0045] The present application provides a purification method of propylene mixed gas containing oxygen-containing organic compounds, which comprises: feeding the propylene mixed gas containing oxygen-containing organic compounds into an absorption tower to absorb the oxygen-containing organic compounds therein by using an absorbent, carrying out gas-liquid separation on the gas phase after absorption, and feeding the gas after gas-liquid separation into secondary compression;

[0046] Feeding the absorption liquid containing oxygen-containing organic compounds into an extraction tower to carry out extraction separation.

[0047] The aforementioned technical solution of the present application can solve the problem in the prior art that propylene is recovered while carrying components such as propylene oxide, formaldehyde, acetaldehyde and propyl aldehyde, and polymerization occurs in the process of temperature rise accompanying compression and pressure increase, which affects the performance of the compressor and reduces the yield of propylene oxide. The present application can solve the aforementioned technical problem by using an absorbent such as desalted water to absorb the overhead gas after primary compression, for example, by spray absorption, carrying out gas-liquid separation on the gas phase after absorption, feeding the gas after gas-liquid separation into secondary compression, and feeding the absorption liquid containing oxygen-containing compounds into an extraction tower to recover the oxygen-containing compounds.

[0048] According to a preferred embodiment of the present application, the oxygen-containing organic compounds in the present application at least contain propylene oxide and aldehyde, preferably contain propylene oxide, and one or more of formaldehyde, acetaldehyde and propyl aldehyde, and more preferably contain propylene oxide, formaldehyde, acetaldehyde and propyl aldehyde.

[0049] According to a preferred embodiment of the present application, the outlet pressure of the secondary compression is 2-3 MPaG, and the outlet temperature is 85-110℃.

[0050] According to a preferred embodiment of the present application, the operating pressure of the extraction tower is 0.4-0.85 MPaG.

[0051] In the present application, the type of the extractant can be selected from a wide range, for example, one or more of cumene and ethylbenzene, and preferably the extractant is cumene. Using cumene as the extractant has the technical effect of not introducing components outside the system.

[0052] In the present application, preferably, the mass ratio of the extractant feed amount and the absorption liquid feed amount of the extraction tower is 0.1-1:1, and preferably 0.15-0.6:1. Using the aforementioned preferred technical solution has the technical effects that the absorption effect is close to the best, the amount of extractant feed is the lowest, and the recovery cost is the lowest.

[0053] In the present application, preferably, the extraction tower is a packed tower, and more preferably the number of theoretical plates is not less than 10.

[0054] In the present application, preferably, the water phase in the lower layer of the extraction tower is recycled to the absorption tower as absorption liquid, and <1% is discharged for post-treatment.

[0055] In the present application, the mass ratio of the absorbent flow rate to the propylene mixed gas feed flow rate is preferably 0.5-2:1. With the foregoing preferred technical solution, the absorption effect is close to the optimum, the absorbent consumption is the lowest, and the loss of propylene oxide hydrolysis is reduced.

[0056] In the present application, the absorbent can be selected from a wide range, and is preferably desalted water.

[0057] In the present application, the absorption tower is preferably a spray absorption tower.

[0058] According to a preferred embodiment of the present application, the propylene mixed gas containing oxygen-containing organic compounds is obtained from the separation product of a propylene epoxidation reaction product; the propylene epoxidation reaction product is separated by a high-pressure propylene recovery tower, the tower bottom product of the high-pressure propylene recovery tower is sent to a low-pressure propylene recovery tower to separate residual propylene, and the propylene mixed gas containing oxygen-containing organic compounds is obtained from the overhead gas discharged from the top of the low-pressure propylene recovery tower.

[0059] According to a preferred embodiment of the present application, the overhead gas is condensed, cooled, and then subjected to primary compression to obtain the propylene mixed gas containing oxygen-containing organic compounds.

[0060] According to a preferred embodiment of the present application, the tower bottom material of the high-pressure propylene recovery tower is subjected to gas-liquid separation, the gas phase is fed from the lower part of the low-pressure propylene recovery tower, the liquid phase is fed from the top of the low-pressure propylene tower, the overhead gas is discharged from the top of the low-pressure propylene tower and then subjected to condensation, cooling, and primary compression to obtain the propylene mixed gas containing oxygen-containing organic compounds.

[0061] According to a preferred embodiment of the present application, the temperature of the overhead gas of the low-pressure propylene tower is 10-25℃, preferably 15-20℃.

[0062] According to a preferred embodiment of the present application, the outlet pressure of the primary compression is 0.15-0.30 MPaG, and the outlet temperature is 60-80℃.

[0063] According to a preferred embodiment of the present application, the outlet pressure of the secondary compression is 2-3 MPaG, and the outlet temperature is 85-110℃.

[0064] According to a preferred embodiment of the present application, the step of gas-liquid separation of the absorbed gas phase comprises: first entering a gas-liquid separation tank for gas-liquid separation, and then the gas phase enters a high-efficiency gas-liquid separation device to remove liquid.

[0065] According to a preferred embodiment of the present application, the present application provides a method for purifying recycled propylene by using the purification method of the present application, which comprises:

[0066] a) the low-pressure propylene recovery column overhead gas is sent to an absorber for absorption, the gas phase after absorption is subjected to gas-liquid separation, and the gas after gas-liquid separation is sent to secondary compression;

[0067] b) the absorption liquid containing water, propylene oxide, formaldehyde, acetaldehyde and propionaldehyde is sent from the upper part of the extraction column, and the extractant is sent from the lower part to extract and recover propylene oxide;

[0068] c) the organic phase in the upper part of the extraction column is sent to a crude PO column as feed, and most of the water phase in the lower part of the extraction column is recycled to the absorber as absorption liquid, and a small part is discharged for post-treatment.

[0069] According to the preferred embodiment of the present application, in the present application, the low-pressure propylene recovery column overhead gas after primary compression is subjected to spray absorption with desalted water, the gas phase after absorption is subjected to gas-liquid separation, and the gas after gas-liquid separation is sent to secondary compression; preferably comprising:

[0070] b) the absorption liquid containing water, propylene oxide, formaldehyde, acetaldehyde and propionaldehyde is sent from the upper part of the extraction column, and isopropylbenzene is used as the extractant sent from the lower part to extract and recover propylene oxide;

[0071] c) the organic phase in the upper part of the extraction column is sent to a crude PO column as feed, and most of the water phase in the lower part of the extraction column is recycled to the absorber as absorption liquid, and a small part is discharged for post-treatment.

[0072] According to the preferred embodiment of the present application, the low-pressure propylene recovery column overhead gas temperature is 10-25℃, preferably 15-20℃.

[0073] According to the preferred embodiment of the present application, the primary compression outlet pressure is 0.15-0.30MPaG, and the outlet temperature is 60-80℃.

[0074] According to the preferred embodiment of the present application, the secondary compression outlet pressure is 2-3MPaG, and the outlet temperature is 85-110℃.

[0075] According to the preferred embodiment of the present application, the extraction column operating pressure is 0.40-0.85MPaG.

[0076] According to the preferred embodiment of the present application, the mass ratio of desalted water flow rate of the absorber to gas phase feed flow rate is 0.5:1-2.0:1.

[0077] According to the preferred embodiment of the present application, the gas phase after absorption in the absorber is preferably first subjected to gas-liquid separation in a gas-liquid separation tank, and then the gas phase is subjected to liquid removal in a high-efficiency gas-liquid separation device.

[0078] According to the preferred embodiment of the present application, the extraction column is preferably a packed column, and the number of theoretical plates is not less than 10.

[0079] According to a preferred embodiment of the present application, the mass ratio of the cumene feed quantity of the extraction column to the absorbent feed quantity is 0.1:1.0-1.0:1.0, preferably 0.15:1.0-0.6:1.0.

[0080] According to a preferred embodiment of the present application, >99% of the lower aqueous phase of the extraction column is recycled to the absorption column as absorbent, and <1% is discharged for post-treatment.

[0081] The present application provides a device for purifying recycled propylene, which comprises:

[0082] an absorption column G, a gas-liquid separation unit and a compression unit connected in series with the gas phase outlet of the absorption column;

[0083] an extraction column H connected with the liquid phase outlet of the absorption column G;

[0084] wherein the absorption column is used for spray absorption of the overhead gas of the low-pressure propylene recovery column with an absorbent; the gas-liquid separation unit is used for gas-liquid separation of the gas phase after absorption; and the compression unit is used for compression of the gas after gas-liquid separation.

[0085] The extraction column is used for extractive distillation of the absorbent containing water, propylene oxide, formaldehyde, acetaldehyde and propionaldehyde.

[0086] According to a preferred embodiment of the present application, the device comprises in sequence:

[0087] a low-pressure propylene recovery column B, a first gas-liquid separation tank A arranged at the feed end of the low-pressure propylene recovery column, a column top condenser C, a post-cooler D, a second gas-liquid separation tank E arranged in sequence at the gas phase discharge end of the low-pressure propylene recovery column, and a first-stage compressor F, an inter-stage cooler L and a third gas-liquid separation tank M connected in series with the gas phase outlet of the second gas-liquid separation tank, an absorption column G connected with the gas phase outlet of the third gas-liquid separation tank M;

[0088] a fourth gas-liquid separation tank I connected with the gas phase outlet of the absorption column G;

[0089] a second-stage compressor J connected with the gas phase outlet of the fourth gas-liquid separation tank I;

[0090] an extraction column H connected with the liquid phase outlet of the absorption column G;

[0091] Preferably, the device further comprises a crude PO column K connected with the top outlet of the extraction column H and / or the bottom outlet of the low-pressure propylene recovery column B, for separating and recovering residual propylene oxide.

[0092] According to a preferred embodiment of the present application, the present application provides a method for purifying recycled propylene, which comprises: high-pressure propylene column material 1 enters a low-pressure propylene recovery column B feed first gas-liquid separation tank A, gas phase 2 is fed from the lower part of the low-pressure propylene recovery column B, liquid phase 3 is fed as reflux liquid from the top of the low-pressure propylene recovery column B, the overhead gas 4 enters the overhead condenser C after condensation, the condensed liquid phase 5 enters the low-pressure propylene recovery column top after-cooler D for cooling, the cooled stream 6 enters the second gas-liquid separation tank E for gas-liquid separation, the gas phase 8 enters the primary compressor F, the compressed gas phase 23 enters the inter-stage cooler L after cooling, the cooled gas phase 24 enters the third gas-liquid separation tank M, the overhead gas phase 9 enters the absorption tower G, and is absorbed by the absorbent 10, the absorbed gas 11 enters the fourth gas-liquid separation tank I, after gas-liquid separation, the gas phase 13 enters the secondary compressor J, the gas 15 after secondary compression returns to the high-pressure propylene recovery column, the absorption liquid 12 enters the extraction column H, and is extracted by the extractant 16 to recover propylene oxide, the overhead organic phase 18 and the low-pressure propylene recovery column liquid are combined to form the stream 20 which enters the crude PO column K, the overhead is crude PO 21, the column liquid 22 is sent to subsequent separation, the liquid phase stream 7 of the second gas-liquid separation tank E, the liquid phase stream 25 of the third gas-liquid separation tank M, the column liquid stream 17 of the extraction column H, and the liquid phase stream 14 of the fourth gas-liquid separation tank I are returned to the high-pressure propylene recovery column and / or the low-pressure propylene recovery column as feed.

[0093] According to the present application, preferably, the operating conditions of the extraction column include that the operating pressure of the extraction column is 0.40-0.85 MPaG.

[0094] According to the present application, preferably, the extractant is methylpropylbenzene and / or isopropylbenzene.

[0095] According to the present application, preferably, the mass ratio of the extractant feed amount of the extraction column to the absorption liquid feed amount is 0.1-1:1, preferably 0.15-0.6:1.

[0096] According to the present application, preferably, the extraction column is a packed column with not less than 10 theoretical plates.

[0097] According to the present application, preferably, the lower layer aqueous phase of the extraction column is recycled to the absorption tower as absorption liquid, and <1% is discharged for post-treatment.

[0098] According to the present application, preferably, the operating conditions of the absorption tower include that the mass ratio of the absorbent flow rate to the propylene mixed gas feed flow rate is 0.5-2:1.

[0099] According to the present application, preferably, the absorbent is desalted water.

[0100] According to the present application, preferably, the absorption tower is a spray absorption tower.

[0101] According to the present application, preferably, the temperature of the low-pressure propylene column overhead gas 4 is 10-25°C, preferably 15-20°C.

[0102] According to the present application, preferably, the first-stage compression outlet pressure is 0.15-0.30 MPaG, and the outlet temperature is 60-80°C.

[0103] According to the present application, the second-stage compression outlet pressure is 2-3 MPaG, and the outlet temperature is 85-110°C.

[0104] According to the present application, preferably, the operating conditions of the first-stage compressor include: an inlet pressure of 0.15-0.9 MPaG.

[0105] According to the present application, preferably, the operating temperature of the first gas-liquid separation tank (A) is 70-90°C.

[0106] According to the present application, preferably, the operating temperature of the second gas-liquid separation tank (E) is 32-40°C.

[0107] According to the present application, preferably, the operating temperature of the third gas-liquid separation tank (M) is 32-40°C.

[0108] According to the present application, preferably, the operating temperature of the fourth gas-liquid separation tank (I) is 32-40°C.

[0109] According to the present application, preferably, the operating temperature of the overhead condenser (C) is 32-40°C.

[0110] According to the present application, preferably, the operating temperature of the aftercooler (D) is 15-25°C.

[0111] According to the present application, preferably, the operating temperature of the inter-stage cooler (L) is 32-40°C.

[0112] According to the preferred embodiments of the present application, the method of the present application comprises:

[0113] The propylene epoxidation reaction product is fed into a high-pressure propylene recovery column for separation, and most of the propylene is recovered from the column overhead, and the column bottom product is fed into the low-pressure propylene recovery column as the high-pressure propylene column bottom material 1.

[0114] In the present application, the high-pressure propylene recovery column is used for separating the propylene epoxidation reaction product, and most of the propylene is recovered from the column overhead, and the column bottom product is fed into the low-pressure propylene recovery column for separation of residual propylene.

[0115] In the present application, the column bottom liquid phase after the low-pressure propylene recovery column separates residual propylene is fed into a crude PO column, and most of the propylene oxide is separated from the crude PO column overhead.

[0116] In the present application, the crude PO column is used for separating propylene oxide from various materials.

[0117] In this invention, the product of the propylene epoxidation reaction is a reaction solution obtained from the epoxidation reaction of an organohydroperoxide and an olefin. The epoxidation reaction of organohydroperoxides and olefins is disclosed in the prior art. Depending on the organohydroperoxide, there are two methods: the cumene hydroperoxide method (CHP method) and the ethylbenzene hydroperoxide method (EBHP method). The epoxide alkane is propylene oxide, butylene oxide, or their isomers, preferably butylene oxide, and more preferably 1,2-butylene oxide. Taking the production of 1,2-butylene oxide as an example, the cumene hydroperoxide method (CHP method) uses cumene hydroperoxide (CHP) as an oxidant. CHP epoxidizes 1-butene to obtain 1,2-butylene oxide and α-butylene dimethylbenzyl alcohol. α,αα-dimethylbenzyl alcohol is hydrogenated to generate cumene, and the cumene is oxidized to generate CHP for recycling.

[0118] Example 1

[0119] like Figure 1 As shown, material 1 from the high-pressure propylene tower bottom enters the first gas-liquid separator A of the low-pressure propylene recovery tower B. Gas phase 2 is fed from the lower part of the low-pressure propylene recovery tower B, and liquid phase 3 is fed as reflux from the top of the low-pressure propylene recovery tower B. The top gas 4 enters the top condenser C for condensation, and the condensed liquid phase 5 enters the top aftercooler D of the low-pressure propylene recovery tower for cooling. After cooling, the stream 6 enters the second gas-liquid separator E for gas-liquid separation. Gas phase 8 enters the first-stage compressor F, and after compression, gas phase 23 enters the interstage cooler L. After cooling, gas phase 24 enters the third gas-liquid separator M. Phase 9 enters the absorption tower G and is absorbed by absorbent 10. The absorbed gas 11 enters the fourth gas-liquid separator I. After gas-liquid separation, the gas phase 13 enters the secondary compressor J. After secondary compression, the gas 15 returns to the high-pressure propylene recovery tower. The absorbent 12 enters the extraction tower H. The operating pressure of the extraction tower is 0.80 MPaG. The extraction tower is a packed tower with a theoretical number of 20 plates. It uses extractant 16, cumene, to extract and recover propylene oxide. The organic phase 18 at the top of the tower and the bottom liquid of the low-pressure propylene recovery tower are combined and the resulting stream 20 goes to the crude PO tower K. The top of the tower is crude PO 21, and the bottom liquid 22 goes to subsequent separation. The liquid stream 7 from the second gas-liquid separator E, the liquid stream 25 from the third gas-liquid separator M, the bottom stream 17 from the extraction tower H, and the liquid stream 14 from the fourth gas-liquid separator I are returned to the high-pressure propylene recovery tower and / or the low-pressure propylene recovery tower as feed.

[0120] Operating temperature of the first gas-liquid separator (A): 80℃

[0121] Operating temperature of the second gas-liquid separator (E): 35℃

[0122] Operating temperature of the third gas-liquid separator (M): 35℃

[0123] Operating temperature of the fourth gas-liquid separator (I): 35℃

[0124] Operating temperature of overhead condenser (C): 35°C

[0125] Operating temperature of aftercooler (D): 20°C

[0126] Operating temperature of interstage cooler (L): 35°C

[0127] The gas phase 8 mass composition is propylene 76%, formaldehyde + acetaldehyde 0.05%, propane 5.9%, propylene oxide 18%, water, acetone, cumene and other components are normalized, the pressure is 0.20 MPaG, the temperature is 20°C, after primary pressurization, the temperature is 72.8°C, the pressure is 0.70 MPaG, and cooling is performed to 40°C, after gas-liquid separation, the propylene oxide content in the gas phase is 14.7%, desalted water is used as the absorption liquid, the absorption liquid temperature is 10°C, the absorption liquid water and gas phase feed ratio is 1.438:1, the mass ratio of cumene feed amount and absorption liquid feed amount in the extraction tower is 0.455:1, the secondary compression outlet pressure is 2.20 MPaG, the outlet temperature is 88.6°C, the propylene oxide content entering the secondary compressor is reduced to 0.067%, and the propylene oxide recovery rate in the extraction tower H reaches 99.9%.

[0128] Example 2

[0129] The same as example 1, the gas phase 8 mass composition is propylene 76%, formaldehyde + acetaldehyde 0.05%, propane 5.9%, propylene oxide 18%, water, acetone, cumene and other components are normalized, the pressure is 0.20 MPaG, the temperature is 20°C, after primary pressurization, the temperature is 72.8°C, the pressure is 0.70 MPaG, and cooling is performed to 40°C, after gas-liquid separation, the propylene oxide content in the gas phase is 14.7%, desalted water is used as the absorption liquid, the absorption liquid temperature is 10°C, the absorption liquid water and gas phase feed ratio is 1.259:1, the mass ratio of cumene feed amount and absorption liquid feed amount in the extraction tower is 0.512:1.0, the secondary compression outlet pressure is 2.20 MPaG, the outlet temperature is 88.8°C, the propylene oxide content entering the secondary compressor is reduced to 0.27%, and the propylene oxide recovery rate in the extraction tower H reaches 99.9%.

[0130] Example 3

[0131] Example 1, the gas phase 8 mass composition of propylene 76%, formaldehyde + acetaldehyde 0.05%, propane 5.9%, propylene oxide 18%, water, acetone, cumene and other components content normalized, the pressure is 0.20 MPaG, the temperature is 20 DEG C, after the first stage pressurization, the temperature is 72.8 DEG C, the pressure is 0.70 MPaG, cool to 40 DEG C, after gas-liquid separation, the gas phase enters the absorption tower, the propylene oxide content in the gas phase is 14.7%, use desalted water as the absorption liquid, the absorption liquid temperature is 10 DEG C, the absorption liquid water and gas phase feed ratio is 1.438:1, the extraction tower cumene feed amount and absorption liquid feed amount mass ratio 0.454:1.0, the secondary compression outlet pressure is 2.20 MPaG, the outlet temperature is 93.2 DEG C, the propylene oxide content entering the secondary compressor reduces to 0.32%. The propylene oxide recovery rate in the extraction tower H reaches 99.9%.

[0132] Example 4

[0133] Example 1, the gas phase 8 mass composition of propylene 76%, formaldehyde + acetaldehyde 0.05%, propane 5.9%, propylene oxide 18%, water, acetone, cumene and other components content normalized, the pressure is 0.20 MPaG, the temperature is 20 DEG C, after the first stage pressurization, the temperature is 72.8 DEG C, the pressure is 0.70 MPaG, cool to 40 DEG C, after gas-liquid separation, the gas phase enters the absorption tower, the propylene oxide content in the gas phase is 14.7%, use desalted water as the absorption liquid, the absorption liquid temperature is 30 DEG C, the absorption liquid water and gas phase feed ratio is 1.438:1, the extraction tower cumene feed amount and absorption liquid feed amount mass ratio 0.463:1.0, the secondary compression outlet pressure is 2.20 MPaG, the outlet temperature is 108.2 DEG C, the propylene oxide content entering the secondary compressor reduces to 3.7%. The propylene oxide recovery rate in the extraction tower H reaches 99.9%.

[0134] Example 5

[0135] Example 1, the gas phase 8 mass composition of propylene 76%, formaldehyde + acetaldehyde 0.05%, propane 5.9%, propylene oxide 18%, water, acetone, cumene and other components content normalized, the pressure is 0.20 MPaG, the temperature is 20 DEG C, after the first stage pressurization, the temperature is 72.8 DEG C, the pressure is 0.70 MPaG, cool to 40 DEG C, after gas-liquid separation, the gas phase enters the absorption tower, the propylene oxide content in the gas phase is 14.7%, use desalted water as the absorption liquid, the absorption liquid temperature is 20 DEG C, the absorption liquid water and gas phase feed ratio is 1.438:1, the extraction tower cumene feed amount and absorption liquid feed amount mass ratio 0.456:1.0, the secondary compression outlet pressure is 2.20 MPaG, the outlet temperature is 98.0 DEG C, the propylene oxide content entering the secondary compressor reduces to 0.98%. The propylene oxide recovery rate in the extraction tower H reaches 99.9%.

[0136] Example 6

[0137] The same as example 1, the gas phase 8 mass composition is propylene 76%, formaldehyde + acetaldehyde 0.05%, propane 5.9%, propylene oxide 18%, and the components of water, acetone, cumene, etc. are normalized, the pressure is 0.20 MPaG, the temperature is 20℃, after primary pressurization, the temperature is 72.8℃, the pressure is 0.70 MPaG, and it is cooled to 40℃, after gas-liquid separation, the propylene oxide content in the gas phase is 14.7%, desalted water is used as the absorbing liquid, the absorbing liquid temperature is 15℃, the absorbing liquid water and gas phase feed ratio is 1:1, the mass ratio of the cumene feed amount of the extraction tower and the absorbing liquid feed amount is 0.631:1.0, the secondary compression outlet pressure is 2.20 MPaG, the outlet temperature is 91.1℃, and the propylene oxide content entering the secondary compressor is reduced to 1.35%. The propylene oxide recovery rate in the extraction tower H reaches 99.9%.

[0138] Comparative example 1

[0139] The difference from example 1 is that the purification is carried out using the flow shown in Figure 2 , the absorbing agent stream 10 uses cumene, the absorbing agent stream and gas phase feed ratio is 1.438:1, the extraction tower H is cancelled, the secondary compression outlet pressure is 2.20 MPaG, the outlet temperature is 121.2℃, and the propylene oxide content entering the secondary compressor is reduced to ppm level.

[0140] The above describes the preferred embodiments of the present application in detail, but the present application is not limited thereto. Within the technical concept of the present application, various simple modifications can be made to the technical solutions of the present application, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be considered as disclosed by the present application and belong to the protection scope of the present application.

Claims

1. A method for purifying a propylene mixture containing oxygen-containing organic matter, characterized in that, The method includes: feeding a propylene mixture containing oxygen-containing organic matter into an absorption tower to absorb the oxygen-containing organic matter with an absorbent; performing gas-liquid separation on the absorbed gas phase; and then subjecting the separated gas to secondary compression; and feeding the absorbent containing oxygen-containing organic matter into an extraction tower for extraction separation. The oxygen-containing organic matter contains at least propylene oxide and aldehyde, and the outlet pressure of the secondary compression is 2-3 MPaG; The propylene mixture containing oxygen-containing organic matter is derived from the separation product of the propylene epoxidation reaction. The propylene epoxidation reaction products are separated by a high-pressure propylene recovery tower. The bottom product of the high-pressure propylene recovery tower is sent to a low-pressure propylene recovery tower to separate the residual propylene. The propylene mixture containing oxygen-containing organic matter comes from the overhead gas discharged from the top of the low-pressure propylene recovery tower. The overhead gas is condensed, cooled, and then compressed in one stage to become the propylene mixture containing oxygen-containing organic matter.

2. The purification method according to claim 1, wherein, The oxygen-containing organic compound contains propylene oxide, and one or more of formaldehyde, acetaldehyde, and propionaldehyde.

3. The purification method according to claim 2, wherein, The oxygen-containing organic compound contains propylene oxide, formaldehyde, acetaldehyde, and propionaldehyde.

4. The purification method according to claim 1, wherein, The operating conditions of the absorption tower include: The mass ratio of the absorbent flow rate to the propylene mixed gas feed flow rate is 0.5-2:1; and / or The absorbent is desalinated water; and / or The absorption tower is a spray absorption tower; and / or The outlet temperature of the secondary compressor is 85-110℃.

5. The purification method according to claim 1, wherein, The operating conditions of the extraction tower include: The operating pressure of the extraction tower is 0.4–0.85 MPaG; and / or The extractant is methyl propylbenzene and / or isopropylbenzene; and / or The mass ratio of the extractant feed rate to the absorbent feed rate in the extraction tower is 0.1 to 1:1; and / or The extraction column is a packed column with a theoretical plate number of not less than 10; and / or >99% of the aqueous phase in the lower layer of the extraction tower is recycled to the absorption tower as absorbent, and <1% is discharged for further treatment.

6. The purification method according to claim 5, wherein, The operating conditions of the extraction tower include: the mass ratio of the extractant feed rate to the absorbent feed rate is 0.15 to 0.6:

1.

7. The purification method according to claim 1, wherein, The gas-liquid phase of the high-pressure propylene recovery tower is separated from the bottom of the low-pressure propylene recovery tower. The gas phase is fed from the bottom of the low-pressure propylene recovery tower, and the liquid phase is fed from the top of the low-pressure propylene tower. The top gas is discharged from the top of the low-pressure propylene tower and then condensed and cooled before being compressed in one stage to obtain the propylene mixture containing oxygen-containing organic matter.

8. The purification method according to claim 1, wherein, The primary compressor outlet pressure is 0.15-0.3 MPaG, and the outlet temperature is 60-80℃.

9. The purification method according to any one of claims 1-8, wherein, The steps for gas-liquid separation after absorption include: first, the gas phase enters a gas-liquid separation tank for gas-liquid separation, and then the gas phase enters a high-efficiency gas-liquid separation device for liquid removal.

10. A method for purifying recycled propylene using the purification method according to any one of claims 1-9, characterized in that, The method includes: a) The overhead gas from the low-pressure propylene recovery tower is fed into the absorption tower for absorption by the absorbent. After absorption, the gas phase is separated into gas and liquid phases and then enters the secondary compression stage. b) An absorbent containing water, propylene oxide, formaldehyde, acetaldehyde and propionaldehyde enters from the top of the extraction tower, and an extractant enters from the bottom to extract and recover propylene oxide. c) The upper organic phase of the extraction tower is fed to the crude PO tower as feed, and most of the lower aqueous phase of the extraction tower is recycled to the absorption tower as absorbent, with a small portion discharged for further treatment.

11. An apparatus for purifying recycled propylene, characterized in that, The device includes: Absorption tower (G), a gas-liquid separation unit and a compression unit connected in series with the gas phase outlet of the absorption tower; An extraction tower (H) is connected to the liquid phase outlet of an absorption tower; The absorption tower is used to absorb the top gas of the low-pressure propylene recovery tower using an absorbent; the gas-liquid separation unit is used to separate the absorbed gas phase into gas and liquid phases; and the compression unit is used to compress the gas after gas-liquid separation. The extraction tower is used for extractive distillation of an absorbent containing water, propylene oxide, formaldehyde, acetaldehyde, and propionaldehyde. The device comprises, in sequence: The low-pressure propylene recovery tower (B) includes a first gas-liquid separator (A) located at the feed end of the low-pressure propylene recovery tower, a top condenser (C), an aftercooler (D), a second gas-liquid separator (E) located sequentially at the gas phase outlet end of the low-pressure propylene recovery tower, and a first-stage compressor (F), an interstage cooler (L), and a third gas-liquid separator (M) connected in series with the gas phase outlet of the second gas-liquid separator. An absorption tower (G) is connected to the gas phase outlet of the third gas-liquid separator (M); The fourth gas-liquid separator (I) is connected to the gas phase outlet of the absorption tower (G); A secondary compressor (J) is connected to the gas phase outlet of the fourth gas-liquid separator (I); An extraction tower (H) is connected to the liquid phase outlet of the absorption tower (G).

12. The apparatus according to claim 11, wherein, The apparatus also includes a crude PO tower (K) connected to the top outlet of the extraction tower (H) and / or the bottom outlet of the low-pressure propylene recovery tower (B) for separating and recovering residual propylene oxide.

13. A method for purifying recycled propylene, characterized in that, The method includes: The material (1) from the bottom of the high-pressure propylene tower enters the first gas-liquid separator (A) of the low-pressure propylene recovery tower (B). The gas phase (2) is fed from the lower part of the low-pressure propylene recovery tower (B), and the liquid phase (3) is fed from the top of the low-pressure propylene recovery tower (B) as reflux liquid. The gas at the top of the tower (4) enters the top condenser (C) for condensation. The condensed liquid phase (5) enters the top aftercooler (D) of the low-pressure propylene recovery tower for cooling. The cooled material (6) enters the second gas-liquid separator (E) for gas-liquid separation. The gas phase (8) enters the first-stage compressor (F). The compressed gas phase (23) enters the interstage cooler (L). The cooled gas phase (24) enters the third gas-liquid separator (M). The gas phase at the top of the tower (9) enters the absorption tower (G) and is absorbed by the absorbent (10). The absorbed gas (1) 1) After entering the fourth gas-liquid separator (I), the gas phase (13) enters the secondary compressor (J). After secondary compression, the gas (15) returns to the high-pressure propylene recovery tower. The absorbent (12) enters the extraction tower (H) and uses the extractant (16) to extract and recover propylene oxide. The organic phase (18) at the top of the tower and the bottom liquid of the low-pressure propylene recovery tower are combined and the resulting stream (20) goes to the crude PO tower (K). The top of the tower is crude PO (21), and the bottom liquid (22) goes to the subsequent separation. The liquid stream (7) from the second gas-liquid separator (E), the liquid stream (25) from the third gas-liquid separator (M), the bottom stream (17) from the extraction tower (H), and the liquid stream (14) from the fourth gas-liquid separator (I) are returned to the high-pressure propylene recovery tower and / or the low-pressure propylene recovery tower as feed.

14. The method according to claim 13, wherein, The operating conditions of the extraction tower include: The operating pressure of the extraction tower is 0.4–0.85 MPaG; and / or The extractant is methyl propylbenzene and / or isopropylbenzene; and / or The mass ratio of the extractant feed rate to the absorbent feed rate in the extraction tower is 0.1 to 1:1; and / or The extraction column is a packed column with a theoretical plate number of not less than 10; and / or >99% of the aqueous phase in the lower layer of the extraction tower is recycled to the absorption tower as absorbent, and <1% is discharged for further treatment; and / or The operating conditions of the absorption tower include: The mass ratio of the absorbent flow rate to the propylene mixed gas feed flow rate is 0.5-2:1; and / or The absorbent is desalinated water; and / or The absorption tower is a spray absorption tower; and / or The primary compressor outlet pressure is 0.15–0.3 MPaG, and the outlet temperature is 60–80°C; and / or The secondary compression outlet pressure is 2-3 MPaG, and the outlet temperature is 85-110℃; and / or Operating temperature of the first gas-liquid separator (A): 70–90°C; and / or Operating temperature of the second gas-liquid separator (E): 32–40°C; and / or Operating temperature of the third gas-liquid separator (M): 32–40°C; and / or Operating temperature of the fourth gas-liquid separator (I): 32–40°C; and / or Operating temperature of the overhead condenser (C): 32–40°C; and / or Operating temperature of aftercooler (D): 15–25°C; and / or Operating temperature of interstage cooler (L): 32~40℃.

15. The method according to claim 13, wherein, The operating conditions of the extraction tower include: the mass ratio of the extractant feed rate to the absorbent feed rate is 0.15 to 0.6:1.

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