A method and system for purifying crude alkylene oxide product

Abstract

The application discloses a method and system for purifying a crude alkylene oxide product containing alkylene oxide, hydrocarbon compounds, oxygen-containing compounds and heavy components, which comprises introducing the crude alkylene oxide product into a first separation tower, feeding side line material of the first separation tower into a second separation tower, recycling tower top material of the second separation tower into the first separation tower, and sequentially performing alkali washing and water washing on tower bottom material of the second separation tower. The system comprises a first separation tower, a second separation tower, an alkali washing unit and a water washing unit connected in sequence. The method and system have the advantages of less salt-containing wastewater generated per unit of organic acid, removal of oxygen-containing compounds mainly containing organic acid, and obtaining relatively pure alkylene oxide and a hydrocarbon and heavy component stream.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of purification process of alkylene oxide (such as propylene oxide), and particularly relates to a method and system for purifying crude alkylene oxide. BACKGROUND

[0002] Alkylene oxide, such as propylene oxide (PO), is an important raw material in organic synthesis, and is the third largest propylene derivative besides polypropylene and acrylonitrile, which is used for synthesizing polyether polyol, propionaldehyde, propylene alcohol, propylene glycol, glycerol, synthetic resin, organic acid, surfactant, emulsifier, plasticizer, foam plastic, bactericide, fumigant, detergent, etc.

[0003] Propylene oxide production processes mainly include chlorohydrination method, co-oxidation method, cumene hydroperoxide method and HPPO method. At present, China mainly produces propylene oxide by chlorohydrination method, but the chlorohydrination method has problems of excessive waste and serious pollution; the co-oxidation method is greatly affected by the price of co-product; therefore, the CHPPO method and the HPPO method without co-product have certain advantages.

[0004] CN112010823A realizes the separation of alkylene oxide and the purification of benzyl alcohol by treating the stream containing hydrocarbons and alkylene oxide collected from the top of the alkylene oxide recovery column through an alkali washing water washing system to remove organic acids therein. However, in the method, after the alkylene oxide is subjected to alkali washing water washing, hydrolysis and dissolution loss of the alkylene oxide will inevitably occur. Moreover, the material containing benzyl alcohol and organic acids is subjected to alkali washing water washing, which will lead to difficulty in liquid-liquid phase separation and great loss of benzyl alcohol.

[0005] SUMMARY

[0006] In order to overcome the problems in the prior art, the present application provides a method and system for purifying crude alkylene oxide, which can solve the problems of hydrolysis and dissolution loss of alkylene oxide caused by alkali washing water washing for removing organic acids, and achieve the purposes of purifying alkylene oxide, hydrocarbons and heavy components, etc. The method has the characteristics of simple flow and strong implementability.

[0007] One of the purposes of the present application is to provide a method for purifying crude alkylene oxide, the crude alkylene oxide containing alkylene oxide, hydrocarbon compounds, oxygen-containing compounds and heavy components, the method comprising: introducing the crude alkylene oxide into a first separation column, the material collected from the side line of the first separation column being introduced into a second separation column, the material at the top of the second separation column being recycled back into the first separation column, and the material at the bottom of the second separation column being subjected to alkali washing and water washing in sequence.

[0008] The inventors have found, through theoretical calculations and experiments, that because the boiling point of oxygenates is between that of alkylene oxides (e.g., propylene oxide) and hydrocarbon compounds (e.g., cumene), when using a distillation column to separate alkylene oxides (e.g., propylene oxide) from hydrocarbon compounds (e.g., cumene), oxygenates will form an enrichment phenomenon on the trays. The present invention can obtain relatively pure alkylene oxides (e.g., propylene oxide) and hydrocarbon compounds (e.g., cumene) and heavy components by drawing a stream from the trays with a relatively high concentration of oxygenates and removing the oxygenates, especially organic acids, therein.

[0009] In a preferred embodiment, the alkylene oxide crude product is a propylene oxide crude product, preferably from the epoxidation reaction of cumene hydroperoxide and propylene.

[0010] In a preferred embodiment, the oxygenates include any one or more of aldehydes, organic acids, alcohols, ketones, water; and / or, the heavy components include at least one of propylene glycol, α,α-dimethylbenzyl alcohol, dipropylene glycol, and cumene; and / or, the hydrocarbon compounds include cumene and / or ethylbenzene.

[0011] In a further preferred embodiment, the aldehydes are any one or more of formaldehyde, acetaldehyde, propionaldehyde; and / or, the alcohols are methanol and / or ethanol; and / or, the ketones are acetone; and / or, the organic acids are any one or more of formic acid, acetic acid, propionic acid, and benzoic acid.

[0012] In a preferred embodiment, the alkylene oxide crude product contains 5-40% alkylene oxide, 10-70% hydrocarbon compounds, 0.001-5% (preferably not including 0) oxygenates, and 5-70% heavy components, based on 100% total weight.

[0013] In a further preferred embodiment, the alkylene oxide crude product contains 10-35% alkylene oxide, 20-70% hydrocarbon compounds, 0.002-4% oxygenates, and 10-60% heavy components, based on 100% total weight.

[0014] For example, the alkylene oxide crude product contains 5%, 10%, 15%, 20%, 25%, 30%, 35%, or 40% alkylene oxide, 10%, 20%, 30%, 40%, 50%, 60%, or 70% hydrocarbon compounds, 0.002%, 0.005%, 0.01%, 0.5%, 1%, 5%, 10%, 15%, or 20% oxygenates, and 5%, 10%, 15%, 20%, 30%, 40%, 50%, 60%, or 70% heavy components, based on weight percentage.

[0015] In a preferred embodiment, the side draw position of the first separation column is higher than the feed position of the crude alkylene oxide product.

[0016] The side draw position of the first separation column is higher than the feed position of the crude alkylene oxide product, because the concentration of heavy components such as benzyl alcohol is high and the concentration of oxygen-containing compounds is low below the feed position of the first separation column. The side draw at this position cannot remove the oxygen-containing compounds, and a large amount of heavy components will be drawn out, which will affect the subsequent treatment. Therefore, the side draw position should be higher than the feed position, and it is appropriate to draw from the plate where the concentration of heavy components is low and the concentration of oxygen-containing compounds is high.

[0017] In a further preferred embodiment, the number of theoretical plates between the side draw position of the first separation column and the feed position of the crude alkylene oxide product accounts for 5-70%, preferably 10-60%, of the total number of theoretical plates of the first separation column.

[0018] For example, the number of theoretical plates between the side draw position of the first separation column and the feed position of the crude alkylene oxide product accounts for 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60% or 70% of the total number of theoretical plates of the first separation column.

[0019] In a preferred embodiment, the weight ratio of the side draw material of the first separation column to the crude alkylene oxide product feed is (0.005-0.1):1.

[0020] In a further preferred embodiment, the weight ratio of the side draw material of the first separation column to the crude alkylene oxide product feed in the feed is (0.01-0.05):1.

[0021] For example, the weight ratio of the side draw material of the first separation column to the crude alkylene oxide product feed in the feed is 0.01:1, 0.02:1, 0.03:1, 0.04:1 or 0.05:1.

[0022] Lower than the above range will result in incomplete side draw of oxygen-containing compounds, and higher than the above range will exceed the amount required for complete removal of oxygen-containing compounds.

[0023] In a preferred embodiment, the weight content of heavy components in the side draw material of the first separation column is less than 1 wt%.

[0024] In a further preferred embodiment, the side draw material of the first separation column mainly consists of alkylene oxide, oxygen-containing compound and hydrocarbon compound.

[0025] In a still further preferred embodiment, the side draw material of the first separation column contains 10-70 wt% of alkylene oxide, 5-60 wt% of oxygen-containing compound, 1-50 wt% of hydrocarbon compound and less than 1 wt% of heavy components.

[0026] In a preferred embodiment, the overhead material of the first separation column is drawn off at the top of the column and the bottoms material is drawn off at the bottom of the column.

[0027] In a further preferred embodiment, the overhead material of the first separation column comprises alkylene oxide and oxygenate; and / or, the bottoms material of the first separation column comprises hydrocarbon and heavies.

[0028] In a further preferred embodiment, the overhead material of the first separation column comprises 95 to 99.9 wt% alkylene oxide, 0 to 5 wt% (e.g. 0.1 to 5 wt%) oxygenate; and / or, the bottoms material of the first separation column comprises 10 to 50 wt% hydrocarbon, 10 to 80 wt% heavies.

[0029] In a preferred embodiment, the overhead material of the second separation column is recycled to the first separation column at a position higher than the side draw position of the first separation column.

[0030] In a preferred embodiment, the overhead material of the second separation column is recycled to the first separation column at a position higher than the side draw position of the first separation column.

[0031] In a preferred embodiment, the overhead material of the second separation column comprises alkylene oxide and oxygenate; and / or, the bottoms material of the second separation column comprises hydrocarbon and oxygenate.

[0032] In a preferred embodiment, the overhead material of the second separation column comprises alkylene oxide and oxygenate; and / or, the bottoms material of the second separation column comprises hydrocarbon and oxygenate.

[0033] In a further preferred embodiment, the overhead material of the second separation column comprises 30 to 80 wt% alkylene oxide, 20 to 70 wt% oxygenate; and / or, the bottoms material of the second separation column comprises 10 to 90 wt% hydrocarbon, 1 to 90 wt% (preferably 10 to 90 wt%) oxygenate.

[0034] For example, the overhead material of the second separation column contains 30 wt%, 40 wt%, 50 wt%, 60 wt%, 70 wt%, or 80 wt% of alkylene oxide, 20 wt%, 30 wt%, 40 wt%, 50 wt%, 60 wt%, or 70 wt% of oxygen-containing compounds; and / or, the column bottom material of the second separation column contains 10 wt%, 20 wt%, 30 wt%, 40 wt%, 50 wt%, 60 wt%, 70 wt%, 80 wt%, or 90 wt% of hydrocarbon compounds, 1 wt%, 5 wt%, 10 wt%, 20 wt%, 30 wt%, 40 wt%, 50 wt%, 60 wt%, 70 wt%, 80 wt%, or 90 wt% of oxygen-containing compounds.

[0035] wherein the sum of the mass fractions of the hydrocarbon compounds and the oxygen-containing compounds in the column bottom material of the second separation column is controlled to be 98% to 100%, preferably 99% to 100%.

[0036] In a further preferred embodiment, the weight ratio of the alkylene oxide in the overhead material of the second separation column to the alkylene oxide in the side draw material of the first separation column is controlled to be 99: 100 to 100: 100, preferably 99.9: 100 to 100: 100.

[0037] wherein the main function of the second separation column is to recover the alkylene oxide, and the oxygen-containing compounds and the hydrocarbon compounds are sent to subsequent caustic wash and water wash processes.

[0038] In a preferred embodiment, the weight flow rate of the column bottom material of the second separation column is controlled to be 0.001 to 0.03 times the weight flow rate of the feed of the crude alkylene oxide product in the first separation column.

[0039] In a preferred embodiment, the column bottom material of the second separation column optionally contains oxygen-containing compounds, which mainly include formic acid and / or acetic acid, preferably, the concentration of formic acid is 0.01 to 30 wt% (for example, the concentration of formic acid is 0.01 wt%, 0.05 wt%, 0.1 wt%, 0.5 wt%, 1 wt%, 5 wt%, 10 wt%, 15 wt%, 20 wt%, 25 wt%, or 30 wt%) and the concentration of acetic acid is 0.01 to 30 wt% (for example, the concentration of acetic acid is 0.01 wt%, 0.05 wt%, 0.1 wt%, 0.5 wt%, 1 wt%, 5 wt%, 10 wt%, 15 wt%, 20 wt%, 25 wt%, or 30 wt%) based on the concentration of 100 wt% of the column bottom material of the second separation column.

[0040] In a preferred embodiment, the operating conditions of the first separation column include a number of theoretical plates of 10 to 95, an operating pressure at the top of 0 to 100 kPaG, an operating temperature at the top of 30 to 80 °C, an operating temperature at the bottom of 150 to 220 °C, and a reflux ratio of 0.1 to 20.

[0041] In a further preferred embodiment, the operating conditions of the first separation column include a number of theoretical plates of 20 to 80, an operating pressure at the top of 0 to 90 kPaG, an operating temperature at the top of 30 to 70 °C, an operating temperature at the bottom of 160 to 200 °C, and a reflux ratio of 0.1 to 15.

[0042] For example, the operating conditions of the first separation column include a number of theoretical plates of 20, 30, 40, 50, 60, 70, or 80, an operating pressure at the top of 0, 10 kPaG, 20 kPaG, 30 kPaG, 40 kPaG, 50 kPaG, 60 kPaG, 70 kPaG, 80 kPaG, or 90 kPaG, an operating temperature at the top of 30 °C, 40 °C, 50 °C, 60 °C, or 70 °C, an operating temperature at the bottom of 160 °C, 170 °C, 180 °C, 190 °C, or 200 °C, and a reflux ratio of 0.1, 0.5, 1, 2, 4, 6, 8, 10, 12, 14, or 15.

[0043] wherein the first separation column is used to separate the alkylene oxide from the hydrocarbons and the heavies.

[0044] In a preferred embodiment, the operating conditions of the second separation column include a number of theoretical plates of 5 to 50, an operating pressure at the top of 0 to 100 kPaG, an operating temperature at the top of 40 to 90 °C, an operating temperature at the bottom of 80 to 160 °C, and a reflux ratio of 0 to 5.

[0045] In a further preferred embodiment, in step (2), the second separation column has a number of theoretical plates of 5 to 40, an operating pressure at the top of 0 to 90 kPaG, an operating temperature at the top of 40 to 80 °C, an operating temperature at the bottom of 90 to 160 °C, and a reflux ratio of 0 to 4.

[0046] For example, in step (2), the second separation column has a number of theoretical plates of 5, 10, 15, 20, 25, 30, 35, or 40, an operating pressure at the top of 0, 10 kPaG, 20 kPaG, 30 kPaG, 40 kPaG, 50 kPaG, 60 kPaG, 70 kPaG, 80 kPaG, or 90 kPaG, an operating temperature at the top of 40 °C, 50 °C, 60 °C, 70 °C, or 80 °C, an operating temperature at the bottom of 90 °C, 100 °C, 110 °C, 120 °C, 130 °C, 140 °C, 150 °C, or 160 °C, and a reflux ratio of 0, 1, 2, 3, or 4.

[0047] The second separation tower is used to recover the alkylene oxide from the side stream of the first separation tower and return it to the first separation tower, while providing the tower bottom stream to the caustic water washing section.

[0048] In the above technical solution, the second separation tower can not be equipped with a condenser and a reflux tank, and the overhead gas is directly drawn out, but is equipped with a reboiler.

[0049] In a preferred embodiment, the caustic washing is performed using a caustic solution having a weight concentration of 2-30 wt%, preferably 5-20 wt%.

[0050] For example, the caustic solution has a weight concentration of 2 wt%, 5 wt%, 10 wt%, 15 wt%, 20 wt%, 25 wt%, or 30 wt%.

[0051] In a further preferred embodiment, the caustic is selected from at least one of sodium hydroxide, potassium hydroxide, sodium carbonate, and potassium carbonate.

[0052] In a preferred embodiment, the water washing is performed on the oil phase after the caustic washing.

[0053] The material after the caustic washing mainly contains hydrocarbon compounds and a small amount of α,α-dimethylbenzyl alcohol.

[0054] In a preferred embodiment, the device for caustic washing and water washing is internally provided with one or more coalescing filter cartridges.

[0055] Preferably, the waste caustic solution from the caustic washing is partially recycled; and / or, the water phase from the water washing is partially recycled.

[0056] In a preferred embodiment, the amount of caustic solution used is 1.1-1.8 times, preferably 1.2-1.5 times, the theoretical amount.

[0057] The theoretical amount is the amount of caustic solution theoretically required by various acids in the second separation tower tower bottom material.

[0058] In a further preferred embodiment, the mass flow rate of the caustic solution is obtained as shown in formula (I):

[0059]

[0060] In formula (I), Z represents the mass flow rate of the caustic solution, B represents the multiple of the theoretical amount, preferably 1.1-1.8 (e.g., 1.2-1.5), M 碱 represents the molecular weight of the caustic solution used, A represents the mass flow rate of the second separation tower tower bottom material; x, y, m respectively represent the mass concentrations of various acids contained in the second separation tower tower bottom material, M x represents the molecular weight of the acid with mass concentration x in the second separation tower tower bottom material, My M represents the molecular weight of the acid with mass concentration y in the second separation column bottom material m M represents the molecular weight of the acid with mass concentration y in the second separation column bottom material, a represents the number of carboxyl groups in the molecular structure of the acid with mass concentration x in the second separation column bottom material, b represents the number of carboxyl groups in the molecular structure of the acid with mass concentration y in the second separation column bottom material, n represents the number of carboxyl groups in the molecular structure of the acid with mass concentration m in the second separation column bottom material, and p represents the mass concentration of the lye.

[0061] wherein the ratio of the mass flow rate of the lye to the mass flow rate of the second separation column bottom material is shown in formula (II):

[0062]

[0063] In formula (II), Z, B, M 碱 , A, x, y, m, M x , M y , M m , a, b, n, p have the same definitions as formula (I).

[0064] In the present application, the alkali washing can remove the acid, alcohol, ketone in the oxygen-containing compound, and the water washing can remove the metal ions and the remaining alcohol and ketone and other water-soluble substances brought by the lye.

[0065] CN105503530A and CN105753647A report an industrial alkali method of sodium methoxide process, that is, through the reaction rectification of sodium hydroxide and methanol, water is constantly removed to make the reaction proceed in the positive direction to obtain sodium methoxide. However, in the present application, since the alkali washing and water washing system is carried out at room temperature, and the water content is not controlled at a very low level, therefore, the reaction of sodium hydroxide and methanol in the present application can be ignored, and the removal of methanol is mainly derived from its easy solubility in water.

[0066] In a preferred embodiment, in the water washing, the flow rate weight ratio of water to the second separation column bottom material is (0.01-100):1, preferably (0.1-40):1.

[0067] For example, in the water washing, the flow rate weight ratio of water to the second separation column bottom material is 0.01:1, 0.1:1, 1:1, 10:1, 20:1, 30:1, 40:1, 50:1, 60:1, 70:1, 80:1, 90:1 or 100:1.

[0068] In the present application, due to the preceding treatment, the alkali washing water washing has less content of alkylene oxide, avoiding the dissolution or hydrolysis of propylene oxide, and has the advantages of short residence time for removing organic acid, less amount of salt-containing wastewater generated by treatment unit organic acid, the water content in the organic phase (mainly hydrocarbon compounds) after alkali washing water washing is 10-1000 ppm, and the organic acid content is 0-1 ppm; at the same time, by the method for purifying the crude epoxy alkane product of the present application, the organic acid concentration in the crude epoxy alkane product (first separation column overhead material) can be reduced to within 100 ppm, and the oxygen-containing compound in cumene and heavy components (first separation column bottom material) can be reduced to within 100 ppm.

[0069] In a preferred embodiment, the method comprises:

[0070] 1) introducing the crude epoxy alkane product into a first separation column, respectively discharging the column overhead material and the column bottom material, and side-drawing the material into a second separation column;

[0071] 2) returning the second separation column overhead material to the first separation column, and performing alkali washing on the column bottom material to obtain an organic phase, and then performing water washing on the alkali washing organic phase.

[0072] In the present application, the first separation column overhead material is the purified epoxy alkane, and the material after the final water washing is the purified hydrocarbon compound.

[0073] The second object of the present application is to provide a system for purifying a crude epoxy alkane product, preferably for performing the method of the first object of the present application, wherein the system comprises a first separation column, a second separation column, an alkali washing unit and a water washing unit connected in sequence.

[0074] In a preferred embodiment, the first separation column is provided with a feed inlet, a column overhead material outlet, a column bottom material outlet and a side-drawing outlet.

[0075] In a further preferred embodiment, the first separation column is provided with a feed inlet at the middle and lower part, a column overhead material outlet at the top, a column bottom material outlet at the bottom, and a side-drawing outlet at the middle.

[0076] In a preferred embodiment, the side-drawing outlet of the first separation column is higher than the feed inlet of the first separation column.

[0077] In a further preferred embodiment, the number of theoretical plates between the side-drawing outlet of the first separation column and the feed inlet of the first separation column accounts for 5-70%, preferably 10-60%, of the total number of theoretical plates of the first separation column.

[0078] In a preferred embodiment, the second separation column is provided with a feed inlet, an overhead outlet and a bottom outlet.

[0079] In a further preferred embodiment, the second separation column is provided with a feed inlet at the upper part of the column, an overhead outlet at the top of the column and a bottom outlet at the bottom of the column.

[0080] In a further preferred embodiment, the second separation column is provided with a feed inlet at the upper part of the column, an overhead outlet at the top of the column and a bottom outlet at the bottom of the column.

[0081] In a preferred embodiment, the side draw outlet of the first separation column is connected to the feed inlet of the second separation column.

[0082] In a preferred embodiment, the first separation column is provided with a recycle inlet, which is connected to the overhead outlet of the second separation column.

[0083] In a further preferred embodiment, the recycle inlet of the first separation column is higher than the side draw outlet of the first separation column.

[0084] In a preferred embodiment, the operating conditions of the first separation column include a theoretical plate number of 10-95, an overhead pressure of 0-100 kPaG, an overhead temperature of 30-80°C, a bottom temperature of 150-220°C and a reflux ratio of 0.1-20.

[0085] In a further preferred embodiment, the operating conditions of the first separation column include a theoretical plate number of 20-80, an overhead pressure of 0-90 kPaG, an overhead temperature of 30-70°C, a bottom temperature of 160-200°C and a reflux ratio of 0.1-15.

[0086] In a preferred embodiment, the operating conditions of the second separation column include a theoretical plate number of 5-50, an overhead pressure of 0-100 kPaG, an overhead temperature of 40-90°C, a bottom temperature of 80-160°C and a reflux ratio of 0-5.

[0087] In a further preferred embodiment, in step (2), the second separation column has a theoretical plate number of 5-40, an overhead pressure of 0-90 kPaG, an overhead temperature of 40-80°C, a bottom temperature of 90-160°C and a reflux ratio of 0-4.

[0088] In the above technical solution, the second separation tower can not be equipped with a condenser and a reflux tank, and the overhead gas is directly led out, but is equipped with a reboiler.

[0089] In a preferred embodiment, the caustic washing unit comprises an organic phase inlet, a caustic inlet, an organic phase outlet and a waste caustic outlet; and / or, the water washing unit comprises an organic phase inlet, a water inlet, an organic phase outlet and a waste water outlet.

[0090] In a further preferred embodiment, the organic phase outlet of the caustic washing unit is connected to the water washing unit, preferably to the organic phase inlet of the water washing unit.

[0091] In a still further preferred embodiment, the waste caustic outlet of the caustic washing unit is optionally connected to the caustic inlet (recycled back to the caustic washing unit); and / or, the waste water outlet of the water washing unit is optionally connected to the water inlet (recycled back to the water washing unit).

[0092] In a preferred embodiment, one or more coalescing filter cartridges are arranged inside the caustic washing unit and the water washing unit.

[0093] In the present application, the alkylene oxide comprises one or more of ethylene oxide, propylene oxide, butylene oxide.

[0094] The endpoints of the ranges and any values disclosed herein are not limited to the precise values recited as exactly that endpoint. Any values that fall within the range, including the upper or lower limit, are contemplated as if specifically recited in this disclosure. Any ranges of values recited are inclusive of the values that are precisely recited as the upper or lower limits of the range. Ranges of values can be combined to form new ranges of values that are also contemplated as being specifically disclosed herein. In the following, the individual technical solutions can in principle be combined with each other to form new technical solutions, which should also be considered as being specifically disclosed herein.

[0095] Compared with the prior art, the present application has the following beneficial effects:

[0096] (1) In the method or system of the present application, the caustic washing and water washing processes have the advantages of avoiding the dissolution or hydrolysis of alkylene oxide and the generation of a small amount of salt-containing wastewater by the treatment unit, and can remove oxygen-containing compounds mainly in the form of organic acids to obtain a relatively pure alkylene oxide and a stream of hydrocarbons and heavy components.

[0097] (2) The method or system of the present application can obtain a higher cumene yield, a higher alkylene oxide yield and a higher removal rate of oxygen-containing compounds (such as organic acids, alcohols, ketones, etc.), and in particular, the organic acid content in the obtained cumene organic phase is almost 0, and the water content is also very low. BRIEF DESCRIPTION OF DRAWINGS

[0098] Figure 1 Figure 1 shows a schematic diagram of the system according to the present application; BRIEF DESCRIPTION OF DRAWINGS

[0100] A - first separation column, B - second separation column, C - caustic washing unit, D - water washing unit; 1 - crude alkylene oxide product, 2 - overhead of the first separation column, 3 - column bottom of the first separation column, 4 - side draw of the first separation column, 5 - overhead of the second separation column, 6 - column bottom of the second separation column, 7 - organic phase after caustic washing, 8 - organic phase after water washing, 9 - caustic solution; 10 - waste caustic solution (aqueous phase after caustic washing); 11 - water; 12 - aqueous phase after water washing.

[0101] In Figure 1 which:

[0102] The crude alkylene oxide product 1 enters the first separation column A, the overhead of which is the overhead of the first separation column 2 (mainly the purified alkylene oxide product), and the column bottom of the first separation column 3 is discharged (mainly containing heavy components and hydrocarbons); the side draw 4 (mainly containing alkylene oxide, hydrocarbons and oxygen-containing compounds) enters the second separation column B.

[0103] The overhead of the second separation column 5 (mainly containing propylene oxide and oxygen-containing compounds) is recycled back to the first separation column A, and the column bottom of the second separation column (mainly containing hydrocarbons and oxygen-containing compounds) enters the caustic washing unit C.

[0104] The organic phase after caustic washing 7 enters the water washing unit D, and the aqueous phase after caustic washing, i.e. the waste caustic solution 10, is partly discharged for treatment and partly recycled back to the caustic washing unit (preferably the waste caustic solution is mixed with fresh caustic solution 9).

[0105] The aqueous phase after water washing 12 is discharged for treatment, and the organic phase after water washing is hydrocarbons and a small amount of α,α-dimethylbenzyl alcohol.

[0106] The first separation column A is provided with a reboiler, a condenser and their inlet and outlet streams, the second separation column B is provided with a reboiler and its inlet and outlet streams, and the second separation column B can not be equipped with a condenser and a reflux drum, and the overhead gas is directly discharged. Those skilled in the art can easily understand the process and function, and will not be described in detail. The present application can be applied to any alkylene oxide system such as propylene oxide and butylene oxide, any benzene system such as cumene and ethylbenzene, and any alcohol system such as propylene glycol, α,α-dimethylbenzyl alcohol and phenethyl alcohol. DETAILED DESCRIPTION

[0107] The present invention will now be described in detail with reference to specific embodiments. It should be noted that the following embodiments are only used to further illustrate the present invention and should not be construed as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the content of the present invention are still within the scope of protection of the present invention.

[0108] It should also be noted that the various specific technical features described in the following embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the various possible combinations will not be described separately in this invention.

[0109] Furthermore, various embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention. The resulting technical solutions are part of the original disclosure of this specification and also fall within the protection scope of the present invention.

[0110] Unless otherwise specified, the raw materials used in the examples and comparative examples are all disclosed in the prior art, such as those that can be directly purchased or prepared according to the preparation methods disclosed in the prior art.

[0111] The amount of saline wastewater refers to the sum of alkaline washing wastewater and water washing wastewater.

[0112]

Example 1

[0113] like Figure 1 As shown, the crude alkyl epoxide product (crude propylene oxide product) 1 fed into the first separation tower contains, by weight percentage, 0.1% acetaldehyde, 21% propylene oxide, 0.1% propionaldehyde, 0.1% acetone, 0.1% methanol, 0.2% water, 0.1% formic acid, 0.1% acetic acid, 26.7% cumene, 0.2% 1,2-propanediol, 49% α,α-dimethylbenzyl alcohol, and 2.3% other components. This reaction product enters the 30th plate of the first separation tower. The first separation tower has a total of 40 plates (plates 1 to 40 from the top to the bottom). The operating pressure at the top of the tower is 0.04 MPaG, the operating temperature at the top is 45℃, the operating temperature at the bottom is 193℃, and the reflux ratio is 2.

[0114] In the first separation tower: the top feed contains 97.49 wt% alkyl epoxides and 2.51 wt% oxygenated compounds; the bottom feed contains 32.47 wt% hydrocarbons and 67.53 wt% heavy components; the side stream feed contains 30.16 wt% alkyl epoxides, 29.14 wt% oxygenated compounds, 40.62 wt% hydrocarbons, and 0.08 wt% heavy components.

[0115] The product from the 26th tray of the first separation column is introduced into the first tray of the second separation column, and the mass flow rate of the side-draw is 0.05 times the feed rate. The second separation column has a total of 10 trays, and the operating pressure at the top of the column is 0.04 MPaG, the operating temperature at the top of the column is 67°C, the operating temperature at the bottom of the column is 127°C, and the reflux ratio is 2. The gas phase obtained from the top of the second separation column is returned to the 25th tray of the first separation column. The material from the bottom of the second separation column is sequentially introduced into the alkali washing unit and the water washing unit, and the mass flow rate of the material from the bottom of the second separation column to the alkali washing unit and the water washing unit is 2.2050% of the mass flow rate of the feed to the first separation column.

[0116] In the second separation column, the material at the top of the column contains 53.95 wt% alkylene oxide, 42.86 wt% oxygen-containing compound, and 3.19% hydrocarbon compound; and the material at the bottom of the column contains 88.05 wt% hydrocarbon compound, 11.76 wt% oxygen-containing compound, and 0.19 wt% heavy component. The oxygen-containing compound in the material at the bottom of the second separation column includes 0.35% acetone, 2.35% methanol, 4.53% formic acid, and 4.53% acetic acid.

[0117] The alkali solution is a sodium hydroxide solution with a mass concentration of 10%, and the amount of the sodium hydroxide solution is designed to be 20% more than the amount actually needed. The mass flow rate of the sodium hydroxide solution / the mass flow rate of the material from the bottom of the second separation column is Z / A = 40 x 1.2 x (0.1% / 46 + 0.1% / 60) (1 / 10%) = 83.51%.

[0118] The amount of deionized water / the flow rate of the material from the bottom of the second separation column is 100%.

[0119] The yield of cumene is calculated as the mass of cumene in the organic phase after water washing divided by the mass of cumene in the material from the bottom of the second separation column; the yield of propylene oxide (referring to the side-drawn yield) is calculated as the mass of propylene oxide in the material at the top of the second separation column divided by the mass of propylene oxide in the side-drawn material from the first separation column; the removal rate of organic acid is calculated as the mass of the reduced organic acid in the organic phase after alkali washing and water washing of the material from the bottom of the second separation column divided by the mass of the organic acid in the feed to the first separation column; the removal rate of methanol is calculated as the mass of the reduced methanol in the organic phase after alkali washing and water washing of the material from the bottom of the second separation column divided by the mass of the methanol in the feed to the first separation column; and the removal rate of acetone is calculated as the mass of the reduced acetone in the organic phase after alkali washing and water washing of the material from the bottom of the second separation column divided by the mass of the acetone in the feed to the first separation column, and the same applies hereinafter.

[0120] Experimental results: the yield of cumene is 99.99%, the yield of propylene oxide is 99.99%, the removal rate of organic acid is 99.90%, the removal rate of methanol is 51.71%, and the removal rate of acetone is 7.62%; the content of organic acid in the organic phase after water washing is 0, the water content is 658 ppm, the Na +0.5 ppm, the amount of salt-containing wastewater generated / second separation column column material = 194.08% (indicating that less wastewater is generated in this application); the organic acid concentration in the first separation column overhead material is 0; the oxygen-containing compound concentration in the first separation column column material is <10 ppm.

[0121] [Example 2]

[0122] The process of Example 1 is repeated, except that a sodium carbonate solution is used as the lye, the mass concentration of the sodium carbonate solution is 10%, the addition amount of the sodium carbonate solution takes into account a 20% design margin, and the addition amount of the sodium carbonate solution / process material flow rate: Z / A = 221.30%.

[0123] The addition amount of deionized water / second separation column column material flow rate = 250%.

[0124] The experimental results are: the isopropyl benzene yield is 99.94%, the propylene oxide yield is 99.99%, the organic acid removal rate is 99.90%, the methanol removal rate is 51.75%, the acetone removal rate is 7.70%; the organic acid content in the organic phase after water washing is 0, the water content is 710 ppm, the Na + 0.4 ppm, the amount of salt-containing wastewater generated / second separation column column material flow rate = 482.50%; the organic acid concentration in the first separation column overhead material is 0; the oxygen-containing compound concentration in the first separation column column material is <10 ppm.

[0125] [Example 3]

[0126] The process of Example 1 is repeated, except that the product taken from the side of the 26th tray of the first separation column goes to the first tray of the second separation column, and the gas phase taken from the top of the second separation column is returned to the 25th tray of the first separation column. The second separation column column material goes to the water washing unit, and the ratio of the mass flow rate of the second separation column column material to the mass flow rate of the first separation column feed is 2.238%, of which the oxygen-containing compound mass fraction is 0.36% acetone, 1.86% methanol, 4.47% formic acid, and 4.46% acetic acid.

[0127] The mass concentration of the sodium hydroxide solution is 20%, the addition amount of the sodium hydroxide solution takes into account a 30% design margin, and the mass flow rate of the sodium hydroxide solution / second separation column column material mass flow rate: Z / A = 44.59%.

[0128] The addition amount of deionized water / second separation column column material flow rate 50%.

[0129] The experimental results are as follows: the yield of cumene is 99.97%, the yield of propylene oxide is 99.99%, the removal rate of organic acid is 99.93%, the removal rate of methanol is 41.58%, the removal rate of acetone is 7.93%; the content of organic acid in the organic phase after water washing is 0, the water content is 515 ppm, the Na + The content of organic acid in the overhead material of the first separation tower is 0; the content of oxygen-containing compound in the tower bottom material of the first separation tower is <10 ppm.

[0130]

Example 4

[0131] The process of Example 1 is repeated, except that the mass flow rate of the side line is 0.04 times the feed amount. The tower bottom material of the second separation tower goes to the alkaline washing water washing unit, and the mass flow rate of the tower bottom material of the second separation tower to the mass flow rate of the first separation tower feed is 1.3596%, wherein the mass fraction of the oxygen-containing compound is 1.28% of acetone, 4.33% of methanol, 7.35% of formic acid, and 7.34% of acetic acid.

[0132] The mass concentration of the sodium hydroxide solution is 5%, and the amount of the sodium hydroxide solution added is considered to have a design allowance of 20%. The amount of the sodium hydroxide solution added / the mass flow rate of the tower bottom material of the second separation tower: Z / A=270.83%.

[0133] The amount of deionized water added / the mass flow rate of the tower bottom material of the second separation tower=300%.

[0134] The experimental results are as follows: the yield of cumene is 99.92%, the yield of propylene oxide is 99.99%, the removal rate of organic acid is 99.87%, the removal rate of methanol is 58.85%, and the removal rate of acetone is 17.32%; the content of organic acid in the organic phase after water washing is 0, the water content is 763 ppm, the Na + The content of organic acid in the overhead material of the first separation tower is 0; the content of oxygen-containing compound in the tower bottom material of the first separation tower is <10 ppm.

[0135]

Example 5

[0136] The process of Example 4 is repeated, except that the overhead operating pressure of the first separation tower is 0 MPaG, the overhead operating temperature is 35°C, the tower bottom operating temperature is 180°C, and the reflux ratio is 2. The overhead operating pressure of the second separation tower is 0 MPaG, the overhead operating temperature is 53°C, and the tower bottom operating temperature is 92°C.

[0137] The second separation column bottom material goes to the caustic water washing unit, the mass flow ratio of the first separation column feed is 1.2321%, and the oxygen-containing compound mass fraction is 3.23% for acetone, 7.18% for methanol, 8.11% for formic acid, and 8.09% for acetic acid.

[0138] The mass concentration of the sodium carbonate solution is 20%, the sodium carbonate solution addition amount considers a 40% design allowance, the mass flow of the sodium carbonate solution / the mass flow of the second separation column bottom material: Z / A = 230.86%.

[0139] The deionized water addition amount / the second separation column bottom material flow = 250%.

[0140] The experimental results are as follows: the isopropyl benzene yield is 99.91%, the propylene oxide yield is 99.99%, the organic acid removal rate is 99.82%, the methanol removal rate is 88.45%, and the acetone removal rate is 39.70%; after water washing, the organic acid content in the organic phase is 0, the water content is 718 ppm, the Na + The salt-containing wastewater amount produced / the second separation column bottom material flow = 506.43%; the organic acid concentration in the first separation column top material is 0; and the oxygen-containing compound concentration in the first separation column bottom material is <10 ppm.

[0141]

Example 6

[0142] The process of Example 1 is repeated, except that the side line extraction mass flow is 0.03 times the feed amount. The second separation column bottom material goes to the caustic water washing unit, the mass flow ratio of the first separation column feed is 0.4137%, and the oxygen-containing compound mass fraction is 9.21% for acetone, 17.47% for methanol, 24.16% for formic acid, and 23.68% for acetic acid.

[0143] The mass concentration of the sodium carbonate solution is 15%, the sodium carbonate solution addition amount considers a 25% design allowance, and the sodium carbonate solution addition amount / the second separation column bottom material: Z / A = 812.56%.

[0144] The deionized water addition amount / the second separation column bottom material flow = 850%.

[0145] The experimental results are as follows: the isopropyl benzene yield is 99.27%, the propylene oxide yield is 99.99%, the organic acid removal rate is 98.95%, the methanol removal rate is 72.21%, and the acetone removal rate is 38.02%; after water washing, the organic acid content in the organic phase is 0, the water content is 787 ppm, the Na +The content is 0.5 ppm, and the amount of saline wastewater generated / the material flow rate of the second separation tower bottom = 1737.13%; the organic acid concentration in the top material of the first separation tower is 0; the oxygen-containing compound concentration in the bottom material of the first separation tower is <30 ppm.

[0146] Comparative Example 1

[0147] like Figure 1 As shown, the feed stream to the first separation tower contains, by weight percentage, 0.1% acetaldehyde, 21% propylene oxide, 0.1% propionaldehyde, 0.1% acetone, 0.1% methanol, 0.2% water, 0.1% formic acid, 0.1% acetic acid, 26.7% cumene, 0.2% 1,2-propanediol, 49% α,α-dimethylbenzyl alcohol, and 2.3% other components. These reaction products enter the 30th plate of the first separation tower. The first separation tower has a total of 40 plates (plates 1 to 40 from the top to the bottom). The operating pressure at the top of the tower is 0.04 MPaG, the operating temperature at the top is 44℃, the operating temperature at the bottom is 164℃, and the reflux ratio is 2.

[0148] The product from the side stream of tray 33 in the first separation tower is sent to tray 1 of the second separation tower. The mass flow rate of the side stream is 0.04 times the feed rate. The second separation tower has 10 trays, with an operating pressure of 0.04 MPaG at the top, an operating temperature of 99°C at the top, and an operating temperature of 190°C at the bottom. The vapor phase from the top is returned to tray 32 of the first separation tower. The bottom material of the second separation tower goes to the alkali washing unit and the water washing unit. The mass flow rate of the bottom material of the second separation tower is 3.4825% of the feed mass flow rate of the first separation tower. It contains 62.62 wt% α,α-dimethylbenzyl alcohol, and the mass fractions of oxygenated compounds are 32 ppm acetone, 4 ppm methanol, 0.12% formic acid, and 0.13% acetic acid.

[0149] The sodium hydroxide solution has a mass concentration of 10%, and the amount of sodium hydroxide solution added is designed to have a 20% margin. The mass flow rate of the sodium hydroxide solution / the mass flow rate of the material in the bottom of the second separation tower is: Z / A = 2.29%.

[0150] The amount of deionized water added / the material flow rate of the second separation tower bottom = 3%.

[0151] The loss rate of α,α-dimethylbenzyl alcohol is calculated by dividing the mass of α,α-dimethylbenzyl alcohol in the organic phase of the bottom material of the second separation tower after alkaline washing and water washing by the mass of α,α-dimethylbenzyl alcohol in the bottom material of the second separation tower.

[0152] The experimental results are as follows: the yield of cumene is 99.99%, the yield of propylene oxide is 99.99%, the removal rate of organic acid is 4.34%, the removal rate of methanol is 0.01%, the removal rate of acetone is 0.11%, the loss rate of α,α-dimethylbenzyl alcohol is 1.69%, the content of organic acid in the organic phase after water washing is 0, the content of water is 124 ppm, the content of Na + The content of organic acid in the overhead material of the first separation column is 0, and the content of oxygen-containing compound in the column bottom material of the first separation column is 0.61%.

[0153] It can be seen that in this embodiment, because the side draw position is lower than the feed position, the content of oxygen-containing compound in the side draw stream is too low, resulting in that a large amount of oxygen-containing compound, especially organic acid, cannot be removed, and further resulting in that the content of organic acid in the column bottom material of the first separation column is too high, affecting the subsequent reaction. Moreover, the α,α-dimethylbenzyl alcohol contained in the column bottom material of the second separation column causes serious emulsification in the water washing process, and it is difficult to separate liquid-liquid phases, so the residence time needs to be increased, resulting in that the equipment volume is expanded and the investment is increased.

[0154]

Comparative Example 2

[0155] The process of Example 1 is repeated, and the difference from Example 1 is that in this example, only the first separation column and its feed and overhead and column bottom material streams are provided. Because this example only has a single column, the crude alkylene oxide product can only be separated from cumene and heavy components, and the organic acid, alcohol and ketone brought by the raw material cannot be removed, and need to be treated in the subsequent process. If not treated, the catalyst in the downstream reactor will be deactivated, and the product purity will be low.

[0156] The above detailed description of the present application is made in combination with specific embodiments and exemplary examples, but these descriptions cannot be understood as limiting the present application. Those skilled in the art understand that the technical solutions and embodiments of the present application can be variously replaced, modified or improved without deviating from the spirit and scope of the present application, and these all fall within the scope of the present application. The protection scope of the present application is subject to the appended claims.

Claims

1. A process for purifying a crude alkylene oxide product containing alkylene oxide, hydrocarbon compounds, oxygenates, and heavies, comprising: The crude alkylene oxide product is introduced into a first separation column, a side line of the first separation column is introduced into a second separation column, overhead material of the second separation column is recycled into the first separation column, and column bottom material of the second separation column is sequentially subjected to alkali washing and water washing; The crude alkylene oxide product contains 5-40% of alkylene oxide, 10-70% of hydrocarbon compounds, 0.001-5% of oxygen-containing compounds, and 5-70% of heavy components, based on 100% of the total weight; the side line of the first separation column is located higher than the feeding position of the crude alkylene oxide product, and the recycling position of the overhead material of the second separation column into the first separation column is higher than the side line of the first separation column; The operating conditions of the first separation column include: 10-95 of theoretical plate number, 0-100 kPaG of overhead operating pressure, 30-80℃ of overhead operating temperature, 150-220℃ of column bottom operating temperature, and 0.1-20 of reflux ratio; and the operating conditions of the second separation column include: 5-50 of theoretical plate number, 0-100 kPaG of overhead operating pressure, 40-90℃ of overhead operating temperature, 80-160℃ of column bottom operating temperature, and 0-5 of reflux ratio.

2. The method according to claim 1, wherein the crude alkylene oxide product is a crude propylene oxide product; and / or the oxygen-containing compounds include any one or more of aldehyde, organic acid, alcohol, ketone, and water; and / or the heavy components include at least one of propylene glycol, α,α-dimethylbenzyl alcohol, dipropylene glycol, and cumene; and / or the hydrocarbon compounds include cumene and / or ethylbenzene.

3. The method according to claim 1, wherein the crude alkylene oxide product is obtained from the epoxidation reaction of cumene hydroperoxide and propylene.

4. The method according to claim 1, wherein the theoretical plate number between the side line of the first separation column and the feeding position of the crude alkylene oxide product accounts for 5-70% of the total theoretical plate number of the first separation column; and / or the weight ratio of the side line material of the first separation column to the crude alkylene oxide product feeding is (0.005-0.1):

1.

5. The method according to claim 1, wherein the theoretical plate number between the side line of the first separation column and the feeding position of the crude alkylene oxide product accounts for 10-60% of the total theoretical plate number of the first separation column; and / or the weight ratio of the side line material of the first separation column to the crude alkylene oxide product feeding is (0.01-0.05):

1.

6. The method according to claim 1, wherein the side line material of the first separation column mainly consists of alkylene oxide, oxygen-containing compounds, and hydrocarbon compounds; and / or the overhead material of the first separation column contains alkylene oxide and oxygen-containing compounds; and / or the column bottom material of the first separation column contains hydrocarbon compounds and heavy components.

7. The method according to claim 1, wherein the overhead material of the second separation column mainly consists of alkylene oxide and oxygen-containing compounds; and / or the column bottom material of the second separation column mainly consists of hydrocarbon compounds and oxygen-containing compounds; and / or the column bottom material of the second separation column mainly consists of hydrocarbon compounds and oxygen-containing compounds. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ The weight ratio of alkylene oxide in the overhead material of the second separation column to the alkylene oxide in the side-draw material of the first separation column is 99:100-100:

100.

8. The method of claim 1, wherein, The weight ratio of alkylene oxide in the overhead material of the second separation column to the alkylene oxide in the side-draw material of the first separation column is 99.9:100-100:

100.

9. The method according to any one of claims 1-8, wherein, alkaline washing is performed using an alkali liquor, the weight concentration of the alkali liquor is 2-30 wt%; and / or, the alkali is at least one selected from sodium hydroxide, potassium hydroxide, sodium carbonate, and potassium carbonate; and / or, the amount of alkali liquor is 1.1-1.8 times the theoretical amount.

10. The method according to claim 9, wherein, alkaline washing is performed using an alkali liquor, the weight concentration of the alkali liquor is 5-20 wt%; and / or, the amount of alkali liquor is 1.2-1.5 times the theoretical amount.

11. The method of claim 9, wherein, The mass flow rate of the alkali liquor is obtained according to formula (I): Formula (I) In formula (I), Z represents the mass flow rate of the lye, B represents the multiple of the theoretical amount, and is 1.1-1.8, M 碱 represents the molecular weight of the lye used, A represents the mass flow rate of the second separation column bottom material; x y m respectively represent the mass concentrations of various acids contained in the second separation column bottom material, M x represents the molecular weight of the acid with a mass concentration of x in the second separation column bottom material, M y represents the molecular weight of the acid with a mass concentration of y in the second separation column bottom material, M m represents the molecular weight of the acid with a mass concentration of m in the second separation column bottom material, a represents the number of carboxyl groups in the molecular structure of the acid with a mass concentration of x in the second separation column bottom material, b represents the number of carboxyl groups in the molecular structure of the acid with a mass concentration of y in the second separation column bottom material, n represents the number of carboxyl groups in the molecular structure of the acid with a mass concentration of m in the second separation column bottom material, p represents the mass concentration of the lye.​​ 12. The method according to claim 9, wherein, the water washing is performed on the oil phase after the alkaline washing; and / or, in the water washing, the weight ratio of the flow rate of water to the flow rate of the column bottom material of the second separation column is (0.01-100):

1.

13. The method of claim 9, wherein, in the water washing, the weight ratio of the flow rate of water to the flow rate of the column bottom material of the second separation column is (0.1-40):

1.

14. A system for purifying a crude alkylene oxide product for carrying out the process of any one of claims 1 to 13, wherein, The system comprises a first separation column, a second separation column, an alkaline washing unit, and a water washing unit connected in sequence; the first separation column is provided with a feed inlet, an overhead material outlet, a column bottom material outlet, and a side-draw outlet; the side-draw outlet of the first separation column is higher than the feed inlet of the first separation column, the first separation column is provided with a circulating material inlet connected to the overhead material outlet of the second separation column, and the circulating material inlet of the first separation column is higher than the side-draw outlet of the first separation column.

15. The system of claim 14, wherein, The first separation column is provided with a feed inlet in the middle and lower part, an overhead material outlet at the top, a column bottom material outlet at the bottom, and a side-draw outlet in the middle.

16. The system of claim 15, wherein, The number of theoretical plates between the side-draw outlet of the first separation column and the feed inlet of the first separation column accounts for 5-70% of the total number of theoretical plates of the first separation column.

17. The system of claim 15, wherein, The number of theoretical plates between the side-draw outlet of the first separation column and the feed inlet of the first separation column accounts for 10-60% of the total number of theoretical plates of the first separation column.

18. The system of claim 15, wherein, The second separation column is provided with a feed inlet, an overhead material outlet, and a column bottom material outlet.

19. The system of claim 18, wherein, The feed inlet of the second separation column is connected to the side-draw outlet of the first separation column, the overhead material outlet of the second separation column is connected to the circulating material inlet of the first separation column, and the column bottom material outlet of the second separation column is connected to the alkaline washing unit.

20. The system according to claim 18, wherein, the side-draw outlet of the first separation column is connected to the feed inlet of the second separation column.

21. The system according to any one of claims 14-20, wherein, The caustic wash unit comprises an organic phase inlet, a caustic inlet, an organic phase outlet, and a waste caustic outlet; and / or, the water wash unit comprises an organic phase inlet, a water inlet, an organic phase outlet, and a waste water outlet.

22. The system of claim 21, wherein, The organic phase outlet of the caustic wash unit is connected to the water wash unit.

23. The system of claim 21, wherein, The organic phase outlet of the caustic wash unit is connected to the organic phase inlet of the water wash unit.

24. The system of claim 21, wherein, The waste caustic outlet of the caustic wash unit is optionally connected to the caustic inlet; and / or, the waste water outlet of the water wash unit is optionally connected to the water inlet; and / or, One or more coalescing filter cartridges are disposed within the caustic wash unit and the water wash unit.

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