Oil-water separation device, system and method

Abstract

The invention relates to the field of maleic anhydride process solvent regeneration, and discloses an oil-water mixed emulsion separation device, an oil-water mixed emulsion separation method, a maleic anhydride process solvent regeneration method and a maleic anhydride process solvent regeneration system. The oil-water mixed emulsion separation device is of a horizontal structure and comprises a barrel and a raw material liquid inlet formed in one side of the barrel, and an oil-water pre-separation area, an oil-water coalescence area and a settling separation area which are communicated are sequentially arranged in the barrel from one side of the raw material liquid inlet. The maleic anhydride process solvent regeneration method and system provided by the invention have the advantages of simple process flow, simple device, continuous operation, stable operation, low device energy consumption, high solvent regeneration efficiency, high regeneration quality, low water content in the separated solvent, low solvent content in wastewater and the like. The solvent washing and impurity removal process can be fully carried out, meanwhile, the solvent and wastewater are rapidly separated, the loss of the solvent in the technological process can be reduced, meanwhile, the wastewater treatment difficulty is reduced, and the economic benefits of a refinery plant are greatly improved.

Description

Technical Field

[0001] The present invention relates to the field of regeneration of solvents in maleic anhydride processes, and particularly to an oil-water mixed emulsion separation device and method, and a maleic anhydride process solvent regeneration method and system. Background Art

[0002] Maleic anhydride is an important industrial chemical raw material, widely used in the manufacture of synthetic resins, plastics, coatings and other products. The n-butane oxidation method is currently the most mainstream maleic anhydride production process. During the production process, it is necessary to recover maleic anhydride from the gas-phase products to improve the maleic anhydride yield. The solvent absorption method has been widely used due to its high yield, few by-products and high economic benefits. The main solvents used are diisobutyl hexahydrophthalate (DIBE) or dibutyl phthalate (DBP). During the solvent absorption process, not only maleic anhydride is absorbed, but also reaction by-products such as maleic acid, fumaric acid, acrylic acid, etc. are absorbed or generated. Therefore, solvent recovery is the core of the entire solvent absorption process. The quality of solvent regeneration determines the absorption effect, maleic anhydride yield, the stable operation of the solvent absorption-desorption system, and the subsequent wastewater treatment difficulty.

[0003] Currently, the industrial separation machine system is used to remove impurities from the solvent. The solvent to be treated and desalted water are mixed in a premixing tank by stirring to transfer organic acids and other impurities in the solvent to the water phase, and then the solvent and the water phase are separated by a separator / centrifuge. However, since the density difference between the solvent and water is very small, for example, the relative density of DBP solvent and water is 1046 kg / m 3 , emulsification is likely to occur with water during the separation process, resulting in difficult oil-water separation. After centrifugation, the water contains solvent and the solvent contains a high water content. Factors such as too high stirring rate and too low oil-water ratio during the operation process will exacerbate the emulsification of the solvent and water, but too low stirring rate and too high oil-water ratio will reduce the treatment amount of solvent impurities and reduce the treatment efficiency. After the current industrial separator device is treated, the water content in the solvent is 2% - 3%, and further sedimentation and dehydration are required for recycling; the solvent content in the wastewater is 300 - 1000 mg / L or even higher, which is difficult to be degraded in the subsequent biochemical treatment, resulting in a large amount of sludge accumulation and a rapid decline in the activity of bacteria, seriously affecting the wastewater treatment difficulty and cost.

[0004] In view of this, the present invention provides a new method and device for solvent regeneration during the solvent recovery process of maleic anhydride processes, realizing the rapid regeneration of the solvent in the maleic anhydride process, oil-water separation, reducing the solvent content in maleic anhydride wastewater, improving the operation stability of the process, and reducing the operation cost. Summary of the Invention

[0005] The object of the present invention is to provide a process flow and device capable of rapidly removing impurities and separating oil and water from the solvent to be treated in the maleic anhydride process. Specifically, an oil-water mixed emulsion separation device and method, and a maleic anhydride process solvent regeneration method and system are provided to improve the efficiency of solvent recovery in the maleic anhydride process, reduce the water content in the solvent and the solvent content in the wastewater, which is beneficial to improving the quality and absorption effect of the recycled solvent, reducing side reactions and the generation of impurities caused by water in the solvent during the process, reducing the operating energy consumption of the device, and significantly reducing the solvent content in the sewage, thus reducing the burden on the subsequent sewage treatment process.

[0006] The first aspect of the present invention is to provide an oil-water mixed emulsion separation device. The separation device has a horizontal structure and includes a cylinder body, a raw material liquid inlet provided on one side of the cylinder body. Inside the cylinder body, an oil-water pre-separation zone, an oil-water coalescence zone, and a sedimentation separation zone are sequentially arranged and connected in communication from the side of the raw material liquid inlet; the space ratios of the oil-water pre-separation zone, the oil-water coalescence zone, and the sedimentation separation zone in the cylinder body are 0-15%, 35-50%, and 35%-50% respectively;

[0007] A water pocket is provided on the top of the cylinder body of the sedimentation separation zone. The water pocket is connected to the cylinder body, and a wastewater outlet is provided on one side of the water pocket; a recycled solvent outlet is provided at the lower part of the sedimentation separation zone.

[0008] The oil-water mixed emulsion separation device used in the present invention (also called a solvent regenerator in the solvent recovery method and system in the maleic anhydride process) can be applied to the oil-water separation in a strongly acidic system to achieve the oil-water separation with a relatively low content of insoluble impurities and a low density difference (<100 kg / m 3 ), mainly aiming at the solvent-water mixed system in the maleic anhydride process to achieve the separation of the oil-water emulsion with a low density difference and a low viscosity difference.

[0009] In some preferred embodiments of the present invention, a plurality of baffle plates are optionally vertically arranged in the oil-water pre-separation zone. In some preferred embodiments of the present invention, the baffle plates are corrugated baffle plates. The oil-water pre-separation zone uses corrugated baffle plates or corrugated plate packings for pre-separation to achieve the coalescence and growth of larger-sized droplets (oil droplets / water droplets) in the mixed emulsion.

[0010] In some preferred embodiments of the present invention, the number of the baffle plates is 0-10, preferably 2-6.

[0011] In some more preferred embodiments of the present invention, the number of the baffle plates is an even number, wherein the first baffle plate has an upper opening and the last baffle plate has a lower opening.

[0012] In some preferred embodiments of the present invention, the size of the channel between adjacent baffle plates is controlled such that the flow velocity of the liquid through the channel is between 1 and 10 m / s, preferably between 1 and 3 m / s.

[0013] In some preferred embodiments of the present invention, the oil-water coalescence zone includes two vertical packing baffle plates and an oil-water coalescence composite material disposed between the packing baffle plates.

[0014] In some more preferred embodiments of the present invention, the upper part of the packing baffle plate at the feed inlet is open, and the lower part of the packing baffle plate at the discharge outlet is open; and / or, the oil-water coalescence composite material is a combination of a hydrophilic oleophobic material and a lipophilic hydrophobic material.

[0015] In some preferred embodiments of the present invention, the filling volume ratio or mass ratio of the hydrophilic oleophobic material to the lipophilic hydrophobic material is 1:5 to 1:1, preferably 1:5 to 1:3.

[0016] In some preferred embodiments of the present invention, the hydrophilic oleophobic material and the lipophilic hydrophobic material are arranged at intervals between the packing baffle plates; more preferably, when the hydrophilic oleophobic material and the lipophilic hydrophobic material are each fibrous materials, the same type of materials are respectively bundled into fiber bundles and stacked at intervals, and the stacking density is between 1 and 10 kg / L, preferably between 2 and 5 kg / L, and / or, the filling volume ratio of the hydrophilic oleophobic material to the lipophilic hydrophobic material is 1:5 to 1:1, preferably 1:5 to 1:3; if the hydrophilic oleophobic material and the lipophilic hydrophobic material are each granular fillers, the hydrophilic oleophobic material and the lipophilic hydrophobic material are uniformly mixed and filled, and the mass ratio of the hydrophilic oleophobic material to the lipophilic hydrophobic material is 1:5 to 1:1, preferably 1:5 to 1:3; further preferably, the contact angle of the hydrophilic oleophobic material with the solvent under underwater wetting conditions is above 90°, preferably above 110°; and / or, the contact angle of the lipophilic hydrophobic material with water is above 90°, preferably above 110°.

[0017] In some preferred embodiments of the present invention, the hydrophilic oleophobic material and the lipophilic hydrophobic material have acid resistance and solubility in DBP / DIBE solvents.

[0018] The solvent regenerator is a horizontal tank, which is designed according to the working site conditions and the three regions of the oil-water pre-separation zone, the oil-water coalescence zone, and the sedimentation separation zone are optimized according to the type of the tank. The space ratios of the oil-water pre-separation zone, the oil-water coalescence zone, and the sedimentation separation zone in the cylinder are 0-15%, 35-50%, and 35%-50% respectively; in some preferred embodiments of the present invention, the space ratios of the oil-water pre-separation zone, the oil-water coalescence zone, and the sedimentation separation zone in the cylinder are 5%-10%, 40%-50%, and 40%-50% respectively.

[0019] In some preferred embodiments of the present invention, a control baffle is vertically arranged between the sedimentation separation zone and the oil-water coalescence zone. A gap is provided between the control baffle and the upper wall of the cylinder body. An emulsion channel is formed between the control baffle and a packing baffle located on the discharge side of the sedimentation separation zone.

[0020] In some preferred embodiments of the present invention, the packing baffle on one side of the oil-water pre-separation zone is a corrugated baffle; and / or, a metal mesh is provided at the opening between the packing baffle and the cylinder wall to prevent the packing from entering the sedimentation separation zone.

[0021] The packing baffle serves to support the oil-water coalescence composite material and fix it in the oil-water coalescence zone, preventing it from entering the subsequent sedimentation separation zone. The control baffle is arranged behind the packing baffle to control the position where the mixed solution enters the sedimentation separation zone. The gap between the control baffle and the cylinder wall opens upward. The mixed solution after coalescence treatment passes through the gap between the packing baffle and the control baffle and enters the sedimentation separation zone from the upper part of the tank body.

[0022] The gap between the control baffle and the cylinder wall is determined according to the processing capacity of the device. In some preferred embodiments of the present invention, the size of the gap between the control baffle and the upper wall of the cylinder body is such that the flow rate of the liquid passing through the gap is between 1 and 10 m / s, preferably 1 to 3 m / s. The control baffle has an upward opening to ensure that the mixed solution maintains a water-phase feed when entering the sedimentation separation zone, and its feed position is above the oil-water liquid level (since the solvent is denser than water, the lower region is the solvent layer and the upper region is the water layer).

[0023] The water pocket is located above the solvent regenerator and is filled with the water phase. The presence of the water pocket is to ensure that the wastewater discharge port is far from the oil-water liquid level to reduce the solvent content in the discharged wastewater. In some preferred embodiments of the present invention, a wastewater discharge pipe communicating with the wastewater outlet is provided on the side of the water pocket. Preferably, the wastewater discharge pipe is arranged in the middle region on the side of the water pocket, away from the top of the water pocket; that is, the wastewater discharge pipe is arranged at a position slightly away from the top of the water pocket on the side of the water pocket to reduce the solvent content in the wastewater.

[0024] In some preferred embodiments of the present invention, during use, the water pocket is filled with the water phase and no air is retained.

[0025] In some preferred embodiments of the present invention, filler A is provided at the lower end of the water bag; preferably, filler A is a hydrophilic and oleophobic material; more preferably, filler A is an adsorption filler, and further preferably, the adsorption filler is fiber and / or particles, and / or, the contact angle of the adsorption filler with the solvent used under wetting conditions is above 90°, preferably above 120°; the adsorption filler is fixedly stacked at the lower end of the water bag through a metal mesh plate; or, filler A is a single-layer or multi-layer modified metal mesh and / or oil-water separation membrane.

[0026] In some preferred embodiments of the present invention, the circulating solvent outlet is connected to the solvent discharge pipe; and / or, filler B is provided at the circulating solvent outlet; preferably, filler B is a lipophilic and hydrophobic material;

[0027] More preferably, filler B is an adsorption filler, and further preferably, the adsorption filler is fiber and / or particles, and the contact angle of the adsorption filler with water is above 90°, preferably above 120°; the adsorption filler is fixedly stacked at the front end of the solvent discharge pipe through a metal mesh plate; or, filler B is a single-layer or multi-layer modified metal mesh and / or oil-water separation membrane provided at the front end of the solvent discharge pipe.

[0028] The second aspect of the present invention is to provide a method for separating an oil-water mixed emulsion, including demulsifying and separating a mixed emulsion containing a solvent and water by using the oil-water mixed emulsion separation device described in the first aspect, and then performing dehydration treatment to obtain wastewater and a circulating solvent; wherein, the density of the solvent is greater than that of water.

[0029] In some preferred embodiments of the present invention, the solvent is the solvent used in the solvent recovery section of the maleic anhydride process, preferably one of dibutyl phthalate and diisobutyl hexahydrophthalate.

[0030] In some preferred embodiments of the present invention, the residence time of the mixed emulsion in the solvent regenerator is 0.15 - 2 h, preferably 0.33 - 0.67 h.

[0031] In some preferred embodiments of the present invention, the flow rate of the emulsion through the channel between adjacent baffle plates is between 1 and 10 m / s, preferably between 1 and 3 m / s.

[0032] In some preferred embodiments of the present invention, the flow rate of the emulsion through the gap between the control baffle and the upper wall of the cylinder is between 1 and 10 m / s, preferably between 1 and 3 m / s.

[0033] In some preferred embodiments of the present invention, the oil-water liquid level in the sedimentation separation area is controlled at the upper-middle part of the cylinder body of the oil-water mixed emulsion separation device; preferably, the liquid level height of the solvent layer in the cylinder body is between 50% and 80%, preferably 60-70%; and / or, the oil-water liquid level is controlled by controlling the discharge amounts of the wastewater and the recycled solvent.

[0034] In some preferred embodiments of the present invention, when in use, the water bag is filled with the water phase and no air is left.

[0035] The third aspect of the present invention is to provide an application of the oil-water mixed emulsion separation device described in the first aspect or the oil-water mixed emulsion separation method described in the second aspect in the solvent regeneration of the maleic anhydride process.

[0036] The fourth aspect of the present invention is to provide a regeneration system for the maleic anhydride process solvent, including an oil-water mixer, a filter, and a solvent regenerator connected in sequence; the solvent regenerator is the oil-water mixed emulsion separation device described in the first aspect.

[0037] The oil-water mixer can be a stirring kettle, and the oil-water mixing is achieved by stirring, or it can be other devices that can fully achieve oil-water mixing on the current market. Different from the existing maleic anhydride process that can only perform stirring and mixing at a low intensity (not higher than 100 r / min, otherwise it is easy to cause emulsification of the solvent and water and subsequent difficult separation), in the present technology, the solvent to be treated and the demineralized water are mixed at a high intensity to reach an emulsified state, and then enter the subsequent device for demulsification and separation of the emulsion.

[0038] In some preferred embodiments of the present invention, the oil-water mixer is a stirring kettle.

[0039] In some preferred embodiments of the present invention, the filter includes at least two filters connected in parallel, one open and one standby, or one open and multiple standbys, or multiple open and multiple standbys.

[0040] In some preferred embodiments of the present invention, the feed port of the filter is selectively connected to the wastewater outlet of the oil-water mixed emulsion separation device, and when the filter is switched, the wastewater separated by the solvent regenerator can be used for backwashing.

[0041] The fifth aspect of the present invention is to provide a method for regenerating the maleic anhydride process solvent by using the regeneration system described in the fourth aspect, including:

[0042] Mix the solvent to be treated and the demineralized water in the oil-water mixer to obtain a mixed emulsion;

[0043] Filter the mixed emulsion through a filter to remove insoluble impurities, and then input the filtered mixed emulsion into the solvent regenerator for demulsification and separation, followed by dehydration treatment to obtain wastewater and recycled solvent.

[0044] According to the present invention, optionally, all or part of the wastewater is recycled to the filter for re-filtration. It can be determined according to the specific indicators of the discharged wastewater. If the solvent content in the wastewater exceeds the standard, part or all of the wastewater can be recycled. If the solvent content in the wastewater meets the standard, recycling is not required.

[0045] The maleic anhydride process of the present invention refers to a method for preparing maleic anhydride by the oxidation of n-butane.

[0046] The solvent to be treated is the solvent containing impurities after desorbing maleic anhydride in the solvent recovery unit of the maleic anhydride process. The solvent to be treated contains impurities such as maleic acid, fumaric acid, and acrylic acid. The density of the solvent is greater than that of water, for example, it is one of di-n-butyl phthalate and diisobutyl hexahydrophthalate.

[0047] In some preferred embodiments of the present invention, the mass ratio of the solvent to be treated to demineralized water is 20:1 to 1:20, preferably 20:1 to 5:1. Since the present technology can achieve sufficient mixing, the solvent can be fully washed with less water, reducing the generation of device wastewater. The mass ratio of the solvent to be treated to demineralized water is preferably 20:1 to 5:1.

[0048] In some preferred embodiments of the present invention, the stirring rate of the oil-water mixer is above 100 r / min, preferably 700 - 1200 r / min.

[0049] In some preferred embodiments of the present invention, the oil-water liquid level in the sedimentation and separation area is controlled at the upper-middle part of the cylinder body of the solvent regenerator; preferably,

[0050] The liquid level height of the solvent layer in the cylinder body is between 50% and 80%, preferably 60 - 70%; and / or,

[0051] The oil-water liquid level is controlled by controlling the discharge amounts of the wastewater and the recycled solvent; and / or,

[0052] The residence time of the mixed emulsion in the solvent regenerator is 0.15 - 2 h, preferably 0.33 - 0.67 h.

[0053] The flow rate of the emulsion is related to the channel spacing and the feed flow rate. When the channel spacing is fixed, the flow rate changes with the change of the feed amount / residence time. In the present invention, it is preferably to control the regeneration of the solvent by the residence time. As a reference, preferably, the flow rate of the emulsion through the channels between adjacent baffle plates is between 1 and 10 m / s, preferably 1 to 3 m / s; as a reference, preferably, the flow rate of the emulsion through the gap between the control baffle and the upper wall of the cylinder is between 1 and 10 m / s, preferably 1 to 3 m / s.

[0054] The oil-water mixed emulsion separation device, separation method, maleic anhydride process solvent regeneration method and system provided by the present invention have the advantages of simple process flow, simple device, continuous operation and stable operation, low energy consumption of the device, high solvent regeneration efficiency, high regeneration quality, low water content in the separated solvent and low solvent content in the wastewater. It can fully carry out the washing and impurity removal processes of the solvent, and at the same time quickly realize the separation of the solvent and the wastewater, which can reduce the loss of the solvent in the process, and at the same time reduce the treatment difficulty of the wastewater, and greatly improve the economic benefits of the refinery. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 Maleic anhydride process solvent regeneration method and system.

[0056] 1 - Demineralized water; 2 - Solvent to be treated; 3 - Oil-water mixer; 4, 5 - Filters; 6 - Solvent regenerator; 7 - Wastewater; 8 - Recirculating solvent;

[0057] Figure 2 Schematic structural diagram of the solvent regenerator in the maleic anhydride process solvent recovery process, that is, the oil-water mixed emulsion separation device.

[0058] 6 - Solvent regenerator; 61 - Oil-water pre-separation zone; 62 - Oil-water coalescence zone; 63 - Settling separation zone; 601 - Mixed solvent inlet pipe; 602 - Baffled corrugated plate; 603 - Oil-water coalescence composite packing; 604 - Packing baffle; 605 - Control baffle; 606 - Water pocket; 607 - Wastewater discharge pipe; 608 - Packing A; 609 - Recirculating solvent discharge pipe; 610 - Packing B DETAILED DESCRIPTION OF THE EMBODIMENTS

[0059] The present invention will be specifically described below in conjunction with specific embodiments. It is necessary to point out here that the following embodiments are only for further illustration of the present invention and cannot be construed as limiting the protection scope of the present invention. Some non-essential improvements and adjustments made by those skilled in the art according to the content of the present invention still fall within the protection scope of the present invention.

[0060] In the following examples and comparative examples, the detection method for the solvent content in water is liquid chromatography;

[0061] The detection method for the water content in the solvent is the Karl Fischer moisture determination method;

[0062] The calculation method for the removal rate of organic impurities in the solvent is as follows:

[0063] where λ is the removal rate of organic impurities, and m 0 is the mass of organic impurities in the raw material solvent, and m 1 is the mass of organic impurities in the purified solvent.

[0064] The following describes a new method for solvent recovery of maleic anhydride process solvents in conjunction with the accompanying drawings of the specification:

[0065] The maleic anhydride process of the present invention refers to the method for preparing maleic anhydride by the oxidation of n-butane. The new method for solvent regeneration in the solvent recovery process of this maleic anhydride process is as Figure 1 shown, and the specific process is as follows. The solvent to be treated is the solvent containing impurities to be treated after desorbing maleic anhydride in the solvent recovery unit of the maleic anhydride process. After desorption, the solvent to be treated 2 containing impurities such as maleic acid, fumaric acid, and acrylic acid is mixed with demineralized water 1 in an oil-water mixer 3, so that the impurities in the solvent are transferred into the water phase. After high-intensity water washing in the oil-water mixer 3, the solvent emulsifies with water to form a mixed emulsion. This mixed emulsion is filtered through filters 4 / 5 to separate insoluble impurities such as tar. Among them, filter 4 and filter 5 are in a one-open-one-standby mode (multiple groups of filters can also be used, with several open and several standby), and the filters / filter groups are switched regularly. The filters that are not in operation after switching need to be backwashed. The mixed emulsion filtered through filters 4 / 5 enters a solvent regenerator 6 for dehydration treatment. Through this device, the separation of the solvent and the waste water containing impurities can be achieved. Waste water 7 with a solvent content lower than 150 ppm, preferably lower than 30 ppm, is obtained at the upper part of the device, and a recycled solvent 8 with a water content lower than 0.9%, preferably lower than 0.5%, is obtained at the lower part of the device.

[0066] As Figure 1 shown, the mixed emulsion filtered through filters 4 / 5 enters the solvent regenerator 6 through the combined solvent inlet pipe 601. The new device for solvent regeneration in this maleic anhydride process solvent recovery process is preferably the oil-water mixed emulsion separation device described in the first aspect of the present invention (also called the solvent regenerator in the solvent recovery method and system of the maleic anhydride process).

[0067] Using Figure 2 the designed horizontal solvent regenerator to conduct experiments. As Figure 2 shown, the solvent regenerator 6 is divided into three regions, including an oil-water pre-separation region 61, an oil-water coalescence region 62, and a sedimentation separation region 63. The mixed emulsion passes through these three regions in sequence to achieve solvent dehydration treatment.

[0068] In the oil-water pre-separation zone 61, a baffle corrugated baffle 602 is provided. The mixed emulsion passes through this baffle, enabling the preliminary coalescence of relatively large-sized droplets (oil droplets / water droplets) in the solution. After the preliminary coalescence of the mixed emulsion passing through the oil-water pre-separation zone 61, it enters the oil-water coalescence zone 62. This area is filled with an oil-water coalescence composite material 603. Through the combined action of the coalescence composite material 603, small particles and micro-particle droplets (oil droplets / water droplets) in the mixed emulsion can achieve further coalescence and growth, thereby achieving the effect of demulsification. The oil-water coalescence zone includes a packing baffle 604 with an upper opening and a lower opening, and the oil-water coalescence composite material arranged between the packing baffles. The upper part of the packing baffle 604 at the feed inlet is open, and the lower part of the packing baffle 604 at the discharge outlet is open; the oil-water coalescence composite material is a combination of a hydrophilic oleophobic material and a lipophilic hydrophobic material; entering the oil-water coalescence zone from the upper part, enabling the coalesced oil-water mixture to exit the packing from the lower part. The solution that has achieved micro-particle coalescence and growth in the oil-water coalescence zone 62 enters the sedimentation separation zone 63 after passing through the channel between the packing baffle 604 and the control baffle 605, where further sedimentation separation is carried out. The wastewater containing impurities such as organic acids has a density slightly lower than that of the solvent and accumulates in the upper part of the device. A water pocket 606 is provided in the upper part of the sedimentation separation zone 63. A wastewater discharge pipe 607 is designed on the side of the water pocket. The wastewater containing impurities exits the device through the wastewater discharge pipe 607 and enters the subsequent wastewater treatment unit. Among them, a packing A 608 is provided at the lower end of the water pocket, which can prevent the solvent phase from being discharged from the upper part of the device through the wastewater discharge pipe 607. The solvent deposits downward and exits the device through the recycled solvent discharge pipe 609 for subsequent recycling. Among them, a packing B 610 is provided at the front end of the recycled solvent discharge pipe 609, which can prevent the water phase from being discharged from the lower part of the device through the recycled solvent discharge pipe 609. Among them, in the solvent regenerator used in the embodiment, that is, in the oil-water separation device:

[0069] The space occupancy ratios of the oil-water pre-separation zone, the oil-water coalescence zone, and the sedimentation separation zone in the device are 10%, 40%, and 50% respectively; the number of baffle corrugated plates is 4; both the hydrophilic oleophobic material and the lipophilic hydrophobic material are fibrous materials; the hydrophilic oleophobic material is an acid-resistant fibrous material with a contact angle of 125° with the solvent used underwater, and the lipophilic hydrophobic material is an acid-resistant modified fibrous material with a contact angle of 100° with water; the two materials are respectively bundled into fiber bundles and stacked at intervals, with a stacking density of 4 kg / L; the filling volume ratio of the hydrophilic oleophobic material to the lipophilic hydrophobic material is 1:4; the packing A is a modified polyurethane packing with a contact angle of 134° with the solvent used underwater, and the packing B is a modified metal mesh with a contact angle of 128° with water.

[0070] The solvent used in the following examples is DBP (dibutyl phthalate), and the mass content of organic impurities in the solvent is 2.5% (maleic acid 0.25%, fumaric acid 0.08%, acrylic acid 0.20%, phthalic acid 0.20%, maleic anhydride 0.12%, phthalic anhydride 0.15%, tar 1.5%). The test temperature is 60 - 65°C, and the stirring tank, filter, solvent regenerator, and pipeline are all maintained at a temperature of 60 - 65°C. The oil-water mixer used is a stirring tank, and the stirring rate is 500 - 1100 r / min. The devices used in the test, the operating temperature, the packing type, combination method, bulk density, and bulk volume of the oil-water coalescing composite packing in the device are all the same. The test is carried out by controlling the mixing intensity of the solvent and water and the residence time of the mixed emulsion in the device. Some specific examples are as follows.

[0071] Example 1

[0072] A new method for solvent regeneration during the solvent recovery process of the maleic anhydride process, comprising the following steps:

[0073] (1) The mass flow ratio of the solvent to the demineralized water is 20:1. The solvent and the demineralized water are respectively heated to 60 - 65°C and then enter the stirring tank for stirring and mixing, and the stirring rate is 700 r / min;

[0074] (2) After the mixed emulsion formed by stirring and mixing in the stirring tank is filtered in the filter, it enters the solvent regenerator for solvent regeneration. The residence time of the mixed emulsion in the solvent regenerator is 1 h, and the liquid level height of the solvent layer of the oil-water liquid level in the cylinder is 70%.

[0075] It has been verified that by using the preferred oil-water pre-separation zone, oil-water coalescing zone, and sedimentation separation zone in the present invention, the space occupancy ratio in the device, the number of baffle corrugated plates, the packing with performance within the preferred range in the oil-water coalescing zone, the preferred packing method, the preferred packing A, and the preferred packing B, and the solvent regenerator obtained by changing one or more of the above factors, when experiments are carried out according to the same method as in Example 1, all have technical effects similar to those of Example 1.

[0076] Example 2

[0077] A new method for solvent regeneration during the solvent recovery process of the maleic anhydride process, comprising the following steps:

[0078] (1) The mass flow ratio of the solvent to the demineralized water is 5:1. The solvent and the demineralized water are respectively heated to 60 - 65°C and then enter the stirring tank for stirring and mixing, and the stirring rate is 700 r / min;

[0079] (2) The mixed emulsion formed after stirring and mixing in the stirring kettle is filtered in a filter and then enters a solvent regenerator for solvent regeneration. The residence time of the mixed emulsion in the solvent regenerator is 1 h, and the liquid level height of the solvent layer in the oil-water liquid level in the cylinder is 70%.

[0080] Example 3

[0081] A new method for solvent regeneration in the process of maleic anhydride process solvent recovery, comprising the following steps:

[0082] (1) The mass flow ratio of the solvent to the demineralized water is 1:10. The solvent and the demineralized water are respectively heated to 60 - 65 °C and then enter a stirring kettle for stirring and mixing. The stirring rate is 700 r / min;

[0083] (2) The mixed emulsion formed after stirring and mixing in the stirring kettle is filtered in a filter and then enters a solvent regenerator for solvent regeneration. The residence time of the mixed emulsion in the solvent regenerator is 1 h, and the liquid level height of the solvent layer in the oil-water liquid level in the cylinder is 70%.

[0084] Example 4

[0085] A new method for solvent regeneration in the process of maleic anhydride process solvent recovery, comprising the following steps:

[0086] (1) The mass flow ratio of the solvent to the demineralized water is 5:1. The solvent and the demineralized water are respectively heated to 60 - 65 °C and then enter a stirring kettle for stirring and mixing. The stirring rate is 1200 r / min;

[0087] (2) The mixed emulsion formed after stirring and mixing in the stirring kettle is filtered in a filter and then enters a solvent regenerator for solvent regeneration. The residence time of the mixed emulsion in the solvent regenerator is 1 h, and the liquid level height of the solvent layer in the oil-water liquid level in the cylinder is 70%.

[0088] It has been verified that the solvent regeneration is carried out according to the method of Example 4 above. The difference is that the liquid level height of the solvent layer in the oil-water liquid level in the cylinder is controlled at 60%. The solvent regeneration effect is very close to the result when the liquid level height of the solvent layer in the oil-water liquid level in the cylinder is controlled at 70%, with little change and basically no influence.

[0089] Example 5

[0090] A new method for solvent regeneration in the process of maleic anhydride process solvent recovery, comprising the following steps:

[0091] (1) The mass flow ratio of the solvent to the demineralized water is 5:1. The solvent and the demineralized water are respectively heated to 60 - 65 °C and then enter a stirring kettle for stirring and mixing. The stirring rate is 700 r / min;

[0092] (2) After the mixed emulsion formed by stirring and mixing in the stirring kettle is filtered in the filter, it enters the solvent regenerator for solvent regeneration. The residence time of the mixed emulsion in the solvent regenerator is 0.65 h, and the liquid level height of the solvent layer of the oil-water liquid level in the cylinder is 70%.

[0093] Example 6

[0094] A new method for solvent regeneration in the process of maleic anhydride process solvent recovery, comprising the following steps:

[0095] (1) The mass flow ratio of the solvent to the demineralized water is 5:1. The solvent and the demineralized water are respectively heated to 60 - 65 °C and then enter the stirring kettle for stirring and mixing, and the stirring rate is 700 r / min;

[0096] (2) After the mixed emulsion formed by stirring and mixing in the stirring kettle is filtered in the filter, it enters the solvent regenerator for solvent regeneration. The residence time of the mixed emulsion in the solvent regenerator is 1 h, and the liquid level height of the solvent layer of the oil-water liquid level in the cylinder is 90%.

[0097] Example 7

[0098] Using the solvent regenerator in the examples, the difference is that the liquid level height of the solvent layer of the oil-water liquid level in the cylinder is 35%.

[0099] (1) The mass flow ratio of the solvent to the demineralized water is 5:1. The solvent and the demineralized water are respectively heated to 60 - 65 °C and then enter the stirring kettle for stirring and mixing, and the stirring rate is 700 r / min;

[0100] (2) After the mixed emulsion formed by stirring and mixing in the stirring kettle is filtered in the filter, it enters the solvent regenerator for solvent regeneration. The residence time of the mixed emulsion in the solvent regenerator is 1 h, and the liquid level height of the solvent layer of the oil-water liquid level in the cylinder is 30%.

[0101] Comparative Example 1

[0102] (1) The mass flow ratio of the solvent to the demineralized water is 5:1. The solvent and the demineralized water are respectively heated to 60 - 65 °C and then enter the stirring kettle for stirring and mixing, and the stirring rate is 700 r / min;

[0103] (2) After the mixed emulsion formed by stirring and mixing in the stirring kettle is filtered in the filter, it enters the settling tank for natural sedimentation, and the sedimentation time is 2 h.

[0104] Comparative Example 2

[0105] (1) The mass flow rate ratio of the solvent to the demineralized water is 5:1. The solvent and the demineralized water are respectively heated to 60 - 65 °C and then enter the stirring kettle for stirring and mixing, and the stirring rate is 700 r / min;

[0106] (2) After the mixed emulsion formed by stirring and mixing in the stirring kettle is filtered in the filter, it enters the centrifuge and is centrifugally separated at 2000 r / min, and the centrifugation time is 0.15 h.

[0107] Comparative Example 3

[0108] (1) The mass flow rate ratio of the solvent to the demineralized water is 5:1. The solvent and the demineralized water are respectively heated to 60 - 65 °C and then enter the stirring kettle for stirring and mixing, and the stirring rate is 80 r / min;

[0109] (2) After the impurities in the solvent are removed by stirring and mixing in the stirring kettle (the solution is basically not emulsified), the mixed solution enters the centrifuge and is centrifugally separated at 2000 r / min, and the centrifugation time is 0.15 h.

[0110] Comparative Example 4

[0111] The solvent regenerator in the example is adopted, except that the waste water discharge pipe is arranged at the top of the water pocket.

[0112] (1) The mass flow rate ratio of the solvent to the demineralized water is 5:1. The solvent and the demineralized water are respectively heated to 60 - 65 °C and then enter the stirring kettle for stirring and mixing, and the stirring rate is 700 r / min;

[0113] (2) After the mixed emulsion formed by stirring and mixing in the stirring kettle is filtered in the filter, it enters the solvent regenerator for solvent regeneration. The residence time of the mixed emulsion in the solvent regenerator is 1 h, and the liquid level height of the solvent layer of the oil - water liquid level in the cylinder body is 70%.

[0114] Comparative Example 5

[0115] The solvent regenerator in the example is adopted, except that the space occupation ratios of the oil - water pre - separation area, the oil - water coalescence area, and the sedimentation separation area in the device are 20%, 60%, and 20% respectively.

[0116] (1) The mass flow rate ratio of the solvent to the demineralized water is 5:1. The solvent and the demineralized water are respectively heated to 60 - 65 °C and then enter the stirring kettle for stirring and mixing, and the stirring rate is 700 r / min;

[0117] (2) After the mixed emulsion formed by stirring and mixing in the stirring kettle is filtered in the filter, it enters the solvent regenerator for solvent regeneration. The residence time of the mixed emulsion in the solvent regenerator is 1 h, and the liquid level height of the solvent layer of the oil - water liquid level in the cylinder body is 70%.

[0118] Table 1 below shows the analysis results of the water content in the solvent and the solvent content in the water after the treatments of Examples 1-7 and Comparative Examples 1-5 of the present invention.

[0119] Table 1 Analysis Results of Oil-Water Separation

[0120]

[0121] Summarized from the above Table 1 as follows:

[0122] From the data comparison of the water content in the solvent and the solvent content in the water after the treatments of Examples 1-7, it can be seen that under the condition of the same device structure, this device can use less demineralized water (Examples 1 and 2) to achieve an organic impurity removal rate in the solvent of over 99%. When the amount of demineralized water used is higher (Example 3), the organic impurity removal rate in the solvent increases, but the corresponding water content in the solvent increases significantly. Under the conditions of the same residence time and oil-water ratio, the faster the mixing and stirring rate of the solvent and demineralized water, the slightly higher the oil content in the treated water and the water content in the solvent (Examples 2 and 4). Under the conditions of the same oil-water ratio and stirring rate, when the residence time is above 0.67 h, the oil content in the treated water and the water content in the solvent change little (Examples 2 and 5). Under the conditions of the same oil-water ratio and stirring rate, the liquid level height of the solvent layer in the oil-water liquid level in the cylinder also affects the oil content in the discharged water and the water content in the solvent of the device. When the oil-water liquid level is closer to the upper part of the device, the solvent content in the discharged wastewater is higher (Examples 2 and 6), and when the oil-water liquid level is closer to the lower part of the device, the water content in the discharged solvent is higher (Examples 2 and 7).

[0123] From the comparison of the data on the water content in the solvent and the solvent content in water after treatment in Example 2, Example 5 and Comparative Examples 1 to 3, it can be seen that this device has an obvious improvement effect compared with centrifugal separation and natural sedimentation. Without being treated by a centrifuge or this device, through natural sedimentation, it is very difficult for the emulsified DBP solvent to separate from water. After sedimentation for 2 hours, partial stratification is achieved, but both the solvent content in water and the water content in the solvent are very high (Comparative Example 1). Comparative Example 3 simulates the industrial process of solvent dehydration using a separator in the maleic anhydride process, but the treatment time of the centrifuge is appropriately increased. From the comparison of the data of Comparative Example 3 with those of Example 2 and Example 5, it can be seen that under the same raw material conditions and oil-water feed ratio, after the actual process flow treatment, not only the solvent content in water and the water content in the solvent are higher than those of the present invention, but also the removal rate of impurities in the solvent is significantly lower than that of the present invention. Comparative Example 2 is to increase the stirring rate in the stirring kettle in the existing industrial process technology to cause obvious emulsification of the DBP solvent. From the comparison of the data of Example 2, Example 5, Comparative Example 2 and Comparative Example 3, it can be seen that after the DBP solvent is emulsified, it is difficult to demulsify by means of centrifugal separation. After separation, the solvent content in the wastewater increases significantly, making it difficult to meet the requirements of subsequent sewage treatment, and the water content in the solvent also increases, and further dehydration treatment is required to meet the requirements of solvent recycling.

[0124] From the comparison between Example 2 and Comparative Example 4, it can be seen that due to the very small density difference between the solvent and water and the existence of interfacial tension, a part of the solvent will float on the surface of the water layer, resulting in a relatively high solvent content in the upper part of the water layer. Setting the wastewater discharge pipe at the top of the water package will cause an increase in the solvent content in the discharged wastewater.

[0125] From the comparison between Example 2 and Comparative Example 5, it can be seen that when the volume ratios of the oil-water pre-separation zone and the oil-water coalescence zone are relatively large, but the volume ratio of the sedimentation separation zone is relatively small, at the same throughput, although it is beneficial to the further coalescence of the solvent and water, the residence time of the coalesced oil droplets and water droplets in the sedimentation separation zone is relatively short, resulting in an increase in the oil content in the wastewater and the water content in the solvent, and a decrease in the removal rate of organic impurities in the solvent.

[0126] Generally speaking, after being treated by the device of the present invention, the DBP solvent can achieve rapid dehydration. Under appropriate operating conditions, the solvent content in the separated water is <30 ppm, the water content in the solvent is <0.5%, and the removal rate of organic impurities in the solvent is over 99%.

[0127] It should be noted that the above-described embodiments are only used to explain the present invention and do not constitute any limitation to the present invention. The present invention has been described by referring to exemplary embodiments, but it should be understood that the words used therein are descriptive and explanatory words rather than limiting words. Modifications can be made to the present invention within the scope of the claims of the present invention as provided, and revisions can be made to the present invention without departing from the scope and spirit of the present invention. Although the present invention described therein relates to specific methods, materials, and embodiments, it does not mean that the present invention is limited to the specific examples disclosed therein. On the contrary, the present invention can be extended to all other methods and applications having the same function.

[0128] All publications, patent applications, patents, and other references mentioned in this specification are hereby incorporated by reference in their entirety. Unless otherwise defined, all technical and scientific terms used in this specification have the meanings commonly understood by those skilled in the art. In case of conflict, the definitions in this specification shall prevail.

[0129] When this specification uses prefixes such as "well-known to those skilled in the art", "prior art", or similar terms to introduce materials, substances, methods, steps, devices, or components, etc., the objects introduced by such prefixes cover those commonly used in the art at the time when this application is filed, but also include those that are not commonly used at present but will become commonly recognized in the art as suitable for similar purposes.

[0130] In the scope disclosed in this application document, the endpoints and any values of the ranges are not limited to the exact ranges or values. These ranges or values should be understood to include values close to these ranges or values. For numerical ranges, between the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values, they can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein. In the following text, in principle, the various technical solutions can be combined with each other to obtain new technical solutions, and this should also be regarded as specifically disclosed herein.

[0131] In the context of this specification, except for the content clearly stated, any matters or things not mentioned directly apply to those known in the art without any change.

[0132] Moreover, any embodiment described herein can be freely combined with one or more other embodiments described herein, and the technical solutions or technical ideas formed thereby are regarded as part of the original disclosure or original record of the present invention, and should not be regarded as new content not disclosed or anticipated herein, unless those skilled in the art consider that the combination is obviously unreasonable.

Claims

1. An oil-water mixed emulsion separation device, the separation device is of a horizontal structure, including a cylinder body, a raw material liquid inlet arranged on one side of the cylinder body, and an oil-water pre-separation area, an oil-water coalescence area and a sedimentation separation area which are successively arranged and communicated in the cylinder body from the side of the raw material liquid inlet; the space ratios of the oil-water pre-separation area, the oil-water coalescence area and the sedimentation separation area in the cylinder body are 0-15%, 35-50%, and 35%-50% respectively; A water pocket is arranged on the top of the cylinder body of the sedimentation separation area, the water pocket is communicated with the cylinder body, and a waste water outlet is arranged on one side of the water pocket; a circulating solvent outlet is arranged at the lower part of the sedimentation separation area.

2. The oil-water mixed emulsion separation device according to claim 1, characterized in that: Optionally, a plurality of baffle plates are vertically arranged in the oil-water pre-separation area; Preferably, the number of the baffle plates is 0-10, preferably 2-6; and / or, Preferably, the number of the baffle plates is an even number, wherein the first baffle plate has an upper opening and the last baffle plate has a lower opening.

3. The oil-water mixed emulsion separation device according to claim 1, characterized in that: The oil-water coalescence area includes two vertical packing baffle plates and an oil-water coalescence composite material arranged between the packing baffle plates; preferably: the upper part of the packing baffle plate at the feeding place has an opening, and the lower part of the packing baffle plate at the discharging place has an opening; and / or, the oil-water coalescence composite material is a combination of a hydrophilic oleophobic material and a lipophilic hydrophobic material; more preferably: The filling volume ratio or mass ratio of the hydrophilic oleophobic material to the lipophilic hydrophobic material is 1:5-1:1, preferably 1:5-1:3; and / or, The hydrophilic oleophobic material and the lipophilic hydrophobic material are arranged at intervals between the packing baffle plates; preferably, If the hydrophilic oleophobic material and the lipophilic hydrophobic material are each a fibrous material, the same type of materials are respectively bundled into fiber bundles and stacked at intervals, and the stacking density is 1-10 kg / L, preferably 2-5 kg / L, and / or, the filling volume ratio of the hydrophilic oleophobic material to the lipophilic hydrophobic material is 1:5-1:1, preferably 1:5-1:3; If the hydrophilic oleophobic material and the lipophilic hydrophobic material are each granular filler, the hydrophilic oleophobic material and the lipophilic hydrophobic material are uniformly mixed and filled, and the mass ratio of the hydrophilic oleophobic material to the lipophilic hydrophobic material is 1:5-1:1, preferably 1:5-1:3; Further preferably, the contact angle of the hydrophilic oleophobic material with the used solvent under the underwater wetting condition is above 90°, preferably above 110°; and / or, The contact angle of the lipophilic hydrophobic material with water is above 90°, preferably above 110°.

4. The oil-water mixed emulsion separation device according to claim 1, characterized in that: The space ratios of the oil-water pre-separation area, the oil-water coalescence area and the sedimentation separation area in the cylinder body are 5%-10%, 40%-50%, and 40%-50% respectively; and / or, A control baffle is vertically arranged between the sedimentation separation zone and the oil-water coalescence zone. A gap is provided between the control baffle and the upper wall of the cylinder body. An emulsion channel is formed between the control baffle and the packing baffle on the discharge side of the sedimentation separation zone.

5. The oil-water mixed emulsion separation device according to claim 1, characterized in that: the packing baffle on one side of the oil-water pre-separation zone is a corrugated baffle; and / or, a metal mesh is provided at the opening between the packing baffle and the cylinder wall.

6. The oil-water mixed emulsion separation device according to any one of claims 1-5, characterized in that: a waste water discharge pipe communicating with the waste water outlet is provided on the side surface of the water pocket. Preferably, the waste water discharge pipe is arranged in the middle area of the side surface of the water pocket, away from the top of the water pocket; and / or, the water pocket is filled with the water phase and no air is retained; and / or, packing A is provided at the lower end of the water pocket; preferably, packing A is a hydrophilic and oleophobic material; further preferably, the packing A is an adsorption packing. Further preferably, the adsorption packing is fiber and / or particle, and / or the contact angle of the adsorption packing with the used solvent is above 90°, preferably above 120° under the wetting condition; the adsorption packing is fixedly stacked at the lower end of the water pocket through a metal mesh plate; or, the packing A is a single-layer or multi-layer modified metal mesh and / or oil-water separation membrane.

7. The oil-water mixed emulsion separation device according to any one of claims 1-5, characterized in that: the circulating solvent outlet is connected to a solvent discharge pipe; and / or, packing B is provided at the circulating solvent outlet; preferably, the packing B is a lipophilic and hydrophobic material; further preferably, the packing B is an adsorption packing. Further preferably, the adsorption packing is fiber and / or particle, and the contact angle of the adsorption packing with water is above 90°, preferably above 120°; the adsorption packing is fixedly stacked at the front end of the solvent discharge pipe through a metal mesh plate; or, the packing B is a single-layer or multi-layer modified metal mesh and / or oil-water separation membrane arranged at the front end of the solvent discharge pipe.

8. An oil-water mixed emulsion separation method, which includes using the oil-water mixed emulsion separation device according to any one of claims 1-7 to demulsify and separate a mixed emulsion containing a solvent and water, and then performing dehydration treatment to obtain waste water and a circulating solvent; wherein, the density of the solvent is greater than that of water.

9. The oil-water mixed emulsion separation method according to claim 8, characterized in that: the solvent is a solvent used in the solvent recovery section of the maleic anhydride process, preferably one of dibutyl phthalate and diisobutyl hexahydrophthalate; and / or, the residence time of the mixed emulsion in the solvent regenerator is 0.15-2 h, preferably 0.33-0.67 h; and / or, the flow rate of the emulsion through the channel between adjacent baffle plates is between 1 and 10 m / s, preferably between 1 and 3 m / s; and / or, the flow rate of the emulsion through the gap between the control baffle and the upper wall of the cylinder body is between 1 and 10 m / s, preferably between 1 and 3 m / s.

10. The method for separating an oil-water mixed emulsion according to claim 8 or 9, characterized in that: the oil-water liquid level in the sedimentation separation area is controlled at the upper-middle part of the cylinder body of the oil-water mixed emulsion separation device; preferably, the liquid level height of the solvent layer in the cylinder body is between 50% and 80%, preferably 60 - 70%; and / or, the oil-water liquid level is controlled by controlling the discharge amounts of the wastewater and the recycled solvent.

11. The application of the oil-water mixed emulsion separation device according to any one of claims 1 - 7 or the oil-water mixed emulsion separation method according to any one of claims 9 - 11 in the solvent regeneration of the maleic anhydride process.

12. A regeneration system for a maleic anhydride process solvent, comprising an oil-water mixer, a filter, and a solvent regenerator that are connected in sequence; the solvent regenerator is the oil-water mixed emulsion separation device according to any one of claims 1 - 7.

13. According to the regeneration system of claim 12, characterized in that: the oil-water mixer is a stirring kettle; and / or, the filter comprises at least two filters connected in parallel, one open and one standby or one open and multiple standbys; and / or, the feed port of the filter is selectively connected to the wastewater outlet of the oil-water mixed emulsion separation device.

14. A method for regenerating a maleic anhydride process solvent using the regeneration system according to claim 12 or 13, comprising: mixing a solvent to be treated with demineralized water in the oil-water mixer to obtain a mixed emulsion; filtering the mixed emulsion through the filter to remove insoluble impurities, and then inputting the obtained filtered mixed emulsion into the solvent regenerator for demulsification and separation, and then performing dehydration treatment to obtain wastewater and a recycled solvent.

15. According to the method of claim 14, characterized in that: the mass ratio of oil to water of the solvent to be treated to demineralized water is 20:1 - 1:20, preferably 20:1 - 5:

1.

16. According to the method of claim 14 or 15, characterized in that: the stirring rate of the oil-water mixer is above 100 r / min, preferably 700 - 1200 r / min; and / or, the oil-water liquid level in the sedimentation separation area is controlled at the upper-middle part of the cylinder body of the solvent regenerator; preferably, the liquid level height of the solvent layer in the cylinder body is between 50% and 80%, preferably 60 - 70%; and / or, the oil-water liquid level is controlled by controlling the discharge amounts of the wastewater and the recycled solvent; and / or, the residence time of the mixed emulsion in the solvent regenerator is 0.15 - 2 h, preferably 0.33 - 0.67 h.

Images