Method and device for recovering furfuryl alcohol

Abstract

The invention discloses a method and device for recovering furfuryl alcohol, and the method comprises the following steps: (1) mixing an aqueous solution containing furfuryl alcohol with an extraction agent, and extracting to obtain an extracted aqueous phase and an organic phase; and (2) carrying out rectification separation on the organic phase obtained in the step (1) to obtain furfuryl alcohol. According to the method disclosed by the invention, a separation method combining extraction and rectification is adopted, so that efficient recovery of low-concentration furfuryl alcohol is realized, and meanwhile, the extraction agent can be recycled. The method disclosed by the invention is simple in process and good in economical efficiency and has a good industrial application prospect.

Description

Technical Field

[0001] The invention relates to a method and a device for recovering furfuryl alcohol, and belongs to the technical field of production of furfuryl alcohol derivatives. Background Art

[0002] Furfuryl alcohol, also known as 2-hydroxymethylfuran, is the most important downstream derivative of furfural. Among the global furfural deep processing conversion products, furfuryl alcohol accounts for about 65%. China is the world's largest producer of furfuryl alcohol, with an annual output of more than 300,000 tons worldwide, of which 70% is produced in China. Furfuryl alcohol has a wide range of applications. It is mainly used in the production of resins, in the metal casting industry to make core molds and metal molds with good performance, as a viscosity reducer for epoxy resins, and in the manufacture of polyurethane foams and polyester products. In addition, furfuryl alcohol can also be used in the synthesis of fragrances, anti-ulcer ranitidine, etc., so it is also widely used in food, medicine and other industries.

[0003] At present, the domestic sources of furfuryl alcohol mainly include two processes: furfural gas phase hydrogenation and liquid phase hydrogenation. In the production process of furfuryl alcohol, a large amount of wastewater with a furfuryl alcohol concentration of 0.1 to 20wt% is easily produced. This type of wastewater has a high COD value and cannot be discharged directly. However, if it is sent to a sewage treatment facility, not only is the treatment cost high, but the furfuryl alcohol therein cannot be utilized, resulting in serious waste of resources. Although furfuryl alcohol can be separated by distilling the wastewater, the energy consumption of this method is huge and the economic efficiency of industrial application is poor. Therefore, it is urgent to develop an economical, environmentally friendly and efficient method for recovering furfuryl alcohol. Summary of the invention

[0004] In order to improve the above technical problems, the present invention provides a method for recovering furfuryl alcohol, the method comprising the following steps:

[0005] (1) mixing an aqueous solution containing furfuryl alcohol with an extractant to perform extraction to obtain an extracted aqueous phase and an organic phase;

[0006] (2) The organic phase obtained in step (1) is subjected to rectification and separation to obtain furfuryl alcohol.

[0007] According to an embodiment of the present invention, in step (1), the extractant is selected from one, two or more of acetone, tetrahydrofuran, methyl ethyl ketone, n-butanol, ethyl acetate, ether, isopropyl ether, dichloromethane, chloroform, ethyl bromide, benzene, xylene, carbon tetrachloride, cyclohexane, hexane, n-heptane, methyl isobutyl ketone and o-xylene.

[0008] According to an embodiment of the present invention, in step (1), in the aqueous solution containing furfuryl alcohol, the mass concentration of furfuryl alcohol is 0.1% or more, for example, 0.1% to 20%, for example, 0.1%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19% or 20%. For example, the aqueous solution containing furfuryl alcohol is waste water generated in a method for preparing furfuryl alcohol by gas phase hydrogenation or liquid phase hydrogenation of furfural, wherein the concentration of furfuryl alcohol is 0.1% or more, for example, 0.1% to 20%.

[0009] According to an embodiment of the present invention, in step (1), the mass ratio of the extractant to the aqueous solution containing furfuryl alcohol is 10:1 to 1:10, for example, 10:1, 8:1, 6:1, 4:1, 2:1, 1:1, 1:2, 1:4, 1:6, 1:8 or 1:10.

[0010] According to an embodiment of the present invention, in step (1), the extraction temperature is 5 to 50°C, for example, 5°C, 10°C, 15°C, 20°C, 25°C, 30°C, 35°C, 40°C, 45°C or 50°C.

[0011] According to an embodiment of the present invention, in step (1), the extraction is carried out in an extraction tower. Preferably, the extraction tower is a packed tower or a plate tower. Preferably, the number of theoretical plates of the extraction tower is 1 to 10, for example, 1, 2, 4, 5, 7, 9 or 10. Preferably, the operating pressure of the extraction tower is 50 to 500 kPa, for example, 50 kPa, 100 kPa, 200 kPa, 300 kPa, 400 kPa or 500 kPa.

[0012] Preferably, the aqueous solution containing furfuryl alcohol is fed from the upper part of the extraction column, and the extractant is fed from the lower part of the extraction column. Also preferably, the aqueous solution containing furfuryl alcohol is fed from the top of the extraction column, and the extractant is fed from the bottom of the extraction column.

[0013] According to an embodiment of the present invention, in step (1), the aqueous phase after extraction can be directly sent to a sewage treatment plant for treatment.

[0014] According to an embodiment of the present invention, in step (1), the mass concentration of furfuryl alcohol in the aqueous phase after extraction is less than 0.1%.

[0015] According to an embodiment of the present invention, in step (2), distillation separation is carried out in a distillation tower.

[0016] According to an embodiment of the present invention, in step (2), the distillation tower may be a packed tower or a plate tower. Preferably, a full condenser and a reboiler are also connected to the distillation tower. Preferably, the number of theoretical plates of the distillation tower is 20 to 60. Preferably, the operating pressure of the distillation tower is 50 to 500 kPa, for example, 50 kPa, 100 kPa, 200 kPa, 300 kPa, 400 kPa or 500 kPa. Preferably, the operating temperature of the distillation tower is 50 to 200 ° C. Preferably, the reflux ratio of the distillation tower is 0.1 to 10.

[0017] Preferably, the extracted organic phase is fed from the middle of the distillation tower, for example, from 1 / 3 to 1 / 2 of the number of plates of the distillation tower.

[0018] According to an embodiment of the present invention, in step (2), furfuryl alcohol and the extractant are separated by distillation. For example, the extractant is obtained at the top of a distillation tower, and furfuryl alcohol is obtained in the bottom of the distillation tower.

[0019] According to an embodiment of the present invention, in step (2), the distillation temperature is 50-200°C.

[0020] According to an embodiment of the present invention, in step (2), the purity of furfuryl alcohol obtained after separation is not less than 98.0%, preferably not less than 99.0%.

[0021] According to an embodiment of the present invention, the method further comprises step (3): recycling the separated extractant and reusing it in step (1) to mix with furfuryl alcohol wastewater.

[0022] According to an embodiment of the present invention, a condenser 8 is further provided between the extraction tower 1 and the distillation tower 2, and the condenser 8 is used to heat the organic phase 12 from the top of the extraction tower and cool the top steam 15 from the distillation tower to obtain the preheated organic phase 14 and the top steam condensate 16.

[0023] Preferably, the organic phase 12 from the top of the extraction column is heated by the steam in the condenser 8;

[0024] Preferably, the steam comes from the top of the gas distillation tower, that is, the top steam 15.

[0025] According to an embodiment of the present invention, a first separator 5 is further connected between the condenser 8 and the distillation tower 2; the tower top steam condensate 16 is separated in the first separator 5 to obtain the tower top reflux liquid 17 and the recycled extractant 18. That is, the condenser 8 is connected to the distillation tower 2 through a pipeline, and in addition, the condenser 8, the first separator 5 and the distillation tower 2 are also connected in sequence through various pipelines.

[0026] Preferably, the recycled extractant 18 re-enters the extraction tower 1 as a partial replacement for the raw extractant;

[0027] Preferably, the top reflux liquid 17 enters a distillation tower.

[0028] According to an embodiment of the present invention, the extractant is stored in an extractant storage tank 7 .

[0029] According to an embodiment of the present invention, the first separator 5 is also connected to an extractant storage tank via a pipeline. The recycled extractant is sent to the extractant storage tank.

[0030] According to an embodiment of the present invention, the distillation tower is also connected to a compressor 3, a heat exchanger 4 and a first separator 5 in sequence.

[0031] According to an embodiment of the present invention, the first separator 5 is also connected to the distillation tower through a pipeline.

[0032] According to an embodiment of the present invention, the heat exchanger 4 is also connected to the distillation tower through a pipeline.

[0033] According to an embodiment of the present invention, the extractant is stored in an extractant storage tank 7 .

[0034] According to an embodiment of the present invention, the first separator 5 is connected to the extractant storage tank 7 through a pipeline.

[0035] According to an embodiment of the present invention, a second separator 6 is connected between the distillation tower 2 and the heat exchanger 4. Preferably, the bottom of the distillation tower is connected to the heat exchanger and the second separator in sequence. That is, the heat exchanger 4 is connected to the distillation tower 2 through a pipeline. In addition, the distillation tower 2, the second separator 6 and the heat exchanger 4 are also connected in sequence through pipelines. After part of the produced liquid from the bottom of the distillation tower is heated to steam in the heat exchanger, it flows back to the bottom of the distillation tower to provide rising steam for the distillation tower.

[0036] According to an embodiment of the present invention, the method further comprises step (4): directly selling the separated furfuryl alcohol or using it for the production of furfuryl alcohol downstream chemicals.

[0037] The present invention also provides a recovery device, which is used to implement the above method, and comprises:

[0038] An extraction tower and a distillation tower, wherein the distillation tower is connected to the extraction tower;

[0039] The extraction tower at least comprises an inlet for an aqueous solution containing furfuryl alcohol and an inlet for an extractant.

[0040] According to an embodiment of the present invention, the extraction tower is a packed tower or a plate tower, the number of theoretical plates is 1 to 10, and the operating pressure is 50 to 500 kPa.

[0041] According to an embodiment of the present invention, the temperature of the extraction tower is 5-50°C.

[0042] According to an embodiment of the present invention, the inlet of the aqueous solution containing furfuryl alcohol is located at the upper part of the extraction tower, and the inlet of the extractant is located at the lower part of the extraction tower.

[0043] According to an embodiment of the present invention, the distillation tower is used to recover furfuryl alcohol.

[0044] According to an embodiment of the present invention, the distillation tower is used to recover the extractant.

[0045] According to an embodiment of the present invention, the top of the distillation tower is used to recover the extractant, and the bottom of the distillation tower is used to recover furfuryl alcohol.

[0046] According to an embodiment of the present invention, the top of the distillation tower is also connected to the extractant inlet of the extraction tower.

[0047] According to an embodiment of the present invention, the distillation tower has 20 to 60 theoretical plates.

[0048] According to an embodiment of the present invention, the operating pressure of the distillation tower is 50-500 kPa.

[0049] According to an embodiment of the present invention, the operating temperature of the distillation tower is 50-200°C.

[0050] According to an embodiment of the present invention, the reflux ratio of the distillation tower is 0.1-10.

[0051] According to an embodiment of the present invention, a condenser 8 is further provided between the extraction tower 1 and the distillation tower 2, and the condenser 8 is used to heat the organic phase 12 from the top of the extraction tower and cool the top steam 15 from the distillation tower to obtain the preheated organic phase 14 and the top steam condensate 16.

[0052] Preferably, the organic phase 12 from the top of the extraction column is heated by the steam in the condenser 8;

[0053] Preferably, the steam comes from the top of the distillation tower, that is, the top steam 15.

[0054] According to an embodiment of the present invention, a first separator 5 is further connected between the condenser 8 and the distillation tower 2; the tower top steam condensate 16 is separated in the first separator 5 to obtain tower top reflux liquid 17 and recycled extractant 18.

[0055] Preferably, the recycled extractant 18 re-enters the extraction tower 1 as a partial replacement for the raw extractant;

[0056] Preferably, the top reflux liquid 17 enters a distillation tower.

[0057] According to an embodiment of the present invention, the extractant is stored in an extractant storage tank 7 .

[0058] According to an embodiment of the present invention, the first separator 5 is also connected to an extractant storage tank via a pipeline. The recycled extractant is sent to the extractant storage tank.

[0059] According to an embodiment of the present invention, the distillation tower is also connected to a compressor, a heat exchanger and a first separator in sequence.

[0060] According to an embodiment of the present invention, the first separator is also connected to the distillation tower through a pipeline.

[0061] According to an embodiment of the present invention, the heat exchanger is also connected to the distillation tower through a pipeline.

[0062] According to an embodiment of the present invention, the extractant is stored in an extractant storage tank 7 .

[0063] According to an embodiment of the present invention, the first separator 5 is connected to the extractant storage tank 7 through a pipeline.

[0064] According to an embodiment of the present invention, a second separator 6 is connected between the distillation tower 2 and the heat exchanger 4. Preferably, the bottom of the distillation tower is connected to the heat exchanger and the second separator 6 in sequence. Part of the produced liquid from the bottom of the distillation tower is heated into steam in the heat exchanger and then refluxed to the bottom of the distillation tower to provide rising steam for the distillation tower.

[0065] According to an embodiment of the present invention, the distillation tower is used in the method for recovering furfuryl alcohol of the present invention. To this end, the method for recovering furfuryl alcohol of the present invention further comprises using the distillation tower to perform the above step (2). Beneficial effects of the present invention:

[0066] The method of the present invention adopts a separation method combining extraction and distillation to achieve efficient recovery of low-concentration furfuryl alcohol, and the extractant can be recycled. The method of the present invention has simple process, good economy, and good industrial application prospects. Specifically:

[0067] (1) The method of the present invention uses a process combining extraction and distillation, which reduces the treatment cost of furfuryl alcohol wastewater and avoids the damage to the environment caused by high COD wastewater;

[0068] (2) The extractant used in the present invention is cheap and can be recycled and reused, resulting in less loss;

[0069] (3) The implementation of the method of the present invention does not require complex equipment, catalysts, etc., which greatly simplifies the wastewater treatment process and reduces energy consumption and process costs.

[0070] (4) The method and apparatus of the present invention fully utilize the steam from the top of the distillation tower to heat the organic phase 12 from the top of the extraction tower, fully utilize the condensation latent heat or waste heat in the process flow, greatly reduce the energy consumption of the process flow, and thus reduce the production cost.

[0071] (5) The method and apparatus of the present invention fully utilize the steam from the top of the distillation tower to heat the reboiler of the tower bottom, thereby reducing the energy consumption required for the process and greatly reducing the production cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0072] Figure 1 It is a device diagram of embodiments 4 and 6;

[0073] Figure 2 This is a device diagram of Example 12;

[0074] Among them: 1-extraction tower; 2-distillation tower; 3-compressor; 4-heat exchanger; 5-first separator; 6-second separator; 7-extractant storage tank; 8-condenser; 9-reboiler; 10-furfuryl alcohol-containing wastewater; 11-extractant; 12-organic phase; 13-aqueous phase; 14-preheated organic phase; 15-top steam; 16-top steam condensate; 17-top reflux liquid; 18-reused extractant; 19-fresh extractant; 20-furfuryl alcohol product; 21-top steam after pressurization; 22-bottom produced liquid; 23-bottom reflux steam. DETAILED DESCRIPTION

[0075] The technical scheme of the present invention will be further described in detail below in conjunction with specific embodiments. It should be understood that the following embodiments are only exemplary descriptions and explanations of the present invention and should not be construed as limiting the scope of protection of the present invention. All technologies implemented based on the above content of the present invention are included in the scope that the present invention is intended to protect.

[0076] Unless otherwise specified, the raw materials and reagents used in the following examples are commercially available or can be prepared by known methods.

[0077] For the determination of furfuryl alcohol and extractant content in wastewater, Agilent 7890B gas chromatography was used, equipped with an HP-5 capillary column (30m×0.32μm, 0.25μm) and a FID detector, and the types of substances contained and the content of each substance were detected by the external standard method.

[0078] Embodiment 1:

[0079] A separation device, comprising: an extraction tower and a distillation tower, wherein the distillation tower is connected to the extraction tower;

[0080] The extraction tower at least includes a furfuryl alcohol wastewater inlet and an extractant inlet;

[0081] The distillation tower is used to separate furfuryl alcohol and the extractant.

[0082] In a liquid-liquid extraction tower with 5 theoretical plates, a furfuryl alcohol-water mixture (i.e., furfuryl alcohol wastewater) with a flow rate of 1000 kg / h enters from the first plate, the mass fraction of furfuryl alcohol in the feed is 20%, and the extractant pure methyl isobutyl ketone enters from the fifth plate with a flow rate of 1000 kg / h. The temperature of the extraction tower is 10°C, and the operating pressure of the extraction tower is normal pressure. The mass concentration of furfuryl alcohol in the aqueous phase after extraction is less than 0.01%, and it can enter the wastewater treatment device. The methyl isobutyl ketone phase (i.e., the organic phase after extraction) then enters the distillation tower, the theoretical number of plates of the distillation tower is 60, the feed position of the organic phase after extraction is 30, the reflux ratio is 1, the top temperature is 85.7°C, the bottom temperature is 185°C, the top pressure is 100 kPa, and the bottom pressure is 159 kPa.

[0083] The bottom of the tower produces 200 kg / h of furfuryl alcohol with a mass concentration higher than 99.9%, and the recovery rate of furfuryl alcohol is >99.9%, which can be directly sold or used in downstream chemical production; the top of the tower produces 1036 kg / h of methyl isobutyl ketone with a mass fraction of 95.3%. This process consumes 0.62 tons of low-pressure steam per hour.

[0084] Embodiment 2:

[0085] The operation was the same as in Example 1, except that the flow rate of the extractant pure methyl isobutyl ketone was 500 kg / h.

[0086] The concentration of furfuryl alcohol in the aqueous phase after extraction is less than 0.01%; 200 kg / h of furfuryl alcohol with a concentration higher than 99.9% is produced from the distillation tower, and the recovery rate of furfuryl alcohol is greater than 99.9%; 527.375 kg / h of methyl isobutyl ketone with a mass fraction of 92.3% is produced from the top of the tower. This process consumes 0.36 tons of low-pressure steam per hour.

[0087] Embodiment 3:

[0088] In the device used in this Example 3, the top of the distillation tower is also connected to an extractant storage tank (not shown in the figure).

[0089] The operation is the same as in Example 1, except that the extractant obtained from the top of the distillation tower is all recycled back to the extraction tower for reuse, and only 13.6 kg of fresh extractant methyl isobutyl ketone needs to be added per hour.

[0090] The mass concentration of furfuryl alcohol in the aqueous phase after extraction is less than 0.01%, and the concentration of methyl isobutyl ketone is less than 0.3%; 200 kg / h of furfuryl alcohol with a mass concentration higher than 99.9% is produced from the distillation tower, and the recovery rate of furfuryl alcohol is greater than 99.9%; the methyl isobutyl ketone containing 7.6 wt% of water produced from the top of the tower is all recycled to the extraction tower for repeated use. This process consumes 0.28 tons of low-pressure steam per hour.

[0091] Embodiment 4:

[0092] A kind of Figure 1 The furfuryl alcohol recovery device shown includes an extractant storage tank 7, an extraction tower 1, a condenser 8, and a distillation tower 2 which are connected in sequence;

[0093] A first separator 5 is also connected between the condenser 8 and the distillation tower 2; that is, the condenser 8 is connected to the distillation tower 2 through a pipeline. In addition, the condenser 8, the first separator 5 and the distillation tower 2 are also connected in sequence through pipelines.

[0094] The first separator 5 is also connected to the extractant storage tank 7 through a pipeline;

[0095] A reboiler 9 is provided at the bottom of the distillation tower 2;

[0096] The top of the distillation tower is also connected to an extractant storage tank (not shown in the figure). Figure 1 The recovery method of furfuryl alcohol of the device shown is:

[0097] In a liquid-liquid extraction tower with 5 theoretical plates, a furfuryl alcohol-water mixture (i.e., furfuryl alcohol wastewater) with a flow rate of 1000 kg / h enters from the first plate, the mass fraction of furfuryl alcohol in the feed is 20%, and the extractant 11 methyl isobutyl ketone enters from the fifth plate (the extractant comes from the recycled extractant and fresh extractant taken from the top of the distillation tower 2, and the flow rate of the fresh extractant is 13.6 kg / h), the total flow rate of the extractant is 1000 kg / h, the temperature of the extraction tower is 10°C, and the operating pressure of the extraction tower is normal pressure. The mass concentration of furfuryl alcohol in the aqueous phase 13 after extraction is less than 0.01%, which is recovered from the bottom of the extraction tower 1 and enters the wastewater treatment device.

[0098] The organic phase 12 then enters the condenser 8 and is preheated to 90°C by the top steam 15 from the distillation tower 2. The preheated organic phase 14 enters the distillation tower 2. The condensate 16 after the steam is cooled in the condenser 8 enters the separator and is separated into an aqueous phase 17 and a recycled extractant 18. The recycled extractant is reloaded into the extractant storage tank 7, and the aqueous phase 17 separated in the separator 5 is re-sent to the distillation tower 2.

[0099] The methyl isobutyl ketone phase (i.e. the organic phase after extraction) then enters the distillation tower, the theoretical plate number of the distillation tower is 60, the feeding position of the organic phase after extraction is 30, the reflux ratio is 1, the tower top temperature is 85.7°C, the tower bottom temperature is 185°C, the tower top pressure is 100kPa, and the tower bottom pressure is 159kPa. The recycled extractant separated in the distillation tower is all returned to the extractant storage tank and passed into the extraction tower for reuse.

[0100] This heat integration process consumes 0.18 tons of low-pressure steam per hour, which is about 0.44 tons less than that of Example 1, saving 71% of energy; and about 0.1 tons less than that of Example 3, saving 36% of energy.

[0101] The mass concentration of furfuryl alcohol in the aqueous phase after extraction is lower than 0.01%, and the concentration of methyl isobutyl ketone is lower than 0.3%; 200 kg / h of furfuryl alcohol with a mass concentration higher than 99.9% is produced from the bottom of the rectification tower, and the recovery rate of furfuryl alcohol is higher than 99.9%; the methyl isobutyl ketone containing 8.2 wt% of water produced from the top of the tower is all recycled to the extraction tower for repeated use, and only 13.6 kg of fresh extractant methyl isobutyl ketone needs to be supplemented per hour.

[0102] Embodiment 5:

[0103] In a liquid-liquid extraction tower with 10 theoretical plates, a furfuryl alcohol-water mixture with a flow rate of 1000 kg / h enters from the first plate, the mass fraction of furfuryl alcohol in the feed is 10%, and the extractant n-butanol enters from the 10th plate with a flow rate of 1000 kg / h. The temperature of the extraction tower is 20°C, and the operating pressure of the extraction tower is 100 kPa. The mass concentration of furfuryl alcohol in the aqueous phase after extraction is less than 0.01%. The n-butanol phase (i.e., the organic phase after extraction) then enters the distillation tower, the theoretical number of plates of the distillation tower is 60, the feed position of the mixture is 15, the reflux ratio is 1.2, the top temperature is 96°C, and the bottom temperature is 188°C. The top pressure is 100 kPa, and the bottom pressure is 159 kPa.

[0104] The bottom of the tower produces 100 kg / h of furfuryl alcohol with a mass concentration of 99.9%, and the recovery rate of furfuryl alcohol is >99.9%, which can be directly sold or used in downstream chemical production; the top of the tower produces 454 kg / h of n-butanol with a mass fraction of 75.6%, which can be appropriately supplemented with fresh n-butanol and circulated to the extraction tower for repeated use. This process consumes 1.4 tons of low-pressure steam per hour.

[0105] Example 6

[0106] Use Figure 1 The recovery method of furfuryl alcohol of the device shown is:

[0107] In a liquid-liquid extraction tower with 10 theoretical plates, a furfuryl alcohol-water mixture (i.e., furfuryl alcohol-containing wastewater 10) with a flow rate of 1000 kg / h enters from the first plate, the mass fraction of furfuryl alcohol in the feed is 10%, and the extractant 11 methyl isobutyl ketone enters from the fifth plate (the extractant comes from the recycled extractant and fresh extractant extracted from the top of the distillation tower, and the flow rate of the fresh extractant is 15.4 kg / h), the flow rate is 500 kg / h, the extraction tower temperature is 30°C, and the operating pressure of the extraction tower is 100 kPa.

[0108] The organic phase 12 then enters the condenser 8 and is preheated to 90°C by the top steam 15 from the distillation tower 2. The preheated organic phase 14 enters the distillation tower 2. The condensate 16 after the steam is cooled in the condenser 8 enters the first separator 5 and is separated into an aqueous phase 17 and a recycled extractant 18. The recycled extractant is reloaded into the extractant storage tank 7, and the aqueous phase 17 separated in the first separator is re-sent to the distillation tower 2.

[0109] The methyl isobutyl ketone phase (i.e., the organic phase after extraction) then enters the distillation tower. The theoretical plate number of distillation tower 2 is 30, the mixture feed position is 15, the reflux ratio is 2, the tower top temperature is 108.0°C, the tower bottom temperature is 183.3°C, the tower top pressure is 100kPa, and the tower bottom pressure is 159kPa. This embodiment consumes 0.15 tons of low-pressure steam per hour. Compared with Example 1, the steam consumption is reduced by about 0.47 tons, and the energy saving is 76%; compared with Example 3, the steam consumption is reduced by about 0.13 tons, and the energy saving is 46%.

[0110] The mass concentration of furfuryl alcohol in the aqueous phase 10 after extraction is lower than 0.01%, and the concentration of methyl isobutyl ketone is lower than 0.3%; 100 kg / h of furfuryl alcohol with a mass concentration higher than 99.9% is produced from the bottom of the rectification tower, and the recovery rate of furfuryl alcohol is greater than 99.9%; 484.6 kg / h of methyl isobutyl ketone containing 5.0 wt% of water is produced from the top of the tower, all of which is recycled to the extraction tower for repeated use, and only 15.4 kg of fresh extractant methyl isobutyl ketone needs to be supplemented per hour.

[0111] Example 7

[0112] In a liquid-liquid extraction tower with 10 theoretical plates, a furfuryl alcohol-water mixture with a flow rate of 1000 kg / h enters from the first plate, the mass fraction of furfuryl alcohol in the feed is 10%, and the extractant ethyl acetate enters from the fifth plate with a flow rate of 500 kg / h. The temperature of the extraction tower is 30°C, and the operating pressure of the extraction tower is 150 kPa. The mass concentration of furfuryl alcohol in the aqueous phase after extraction is less than 0.01%. The ethyl acetate phase then enters the distillation tower, the theoretical number of plates of the distillation tower is 30, the feed position of the mixture is 15, the reflux ratio is 3, the top temperature is 70.7°C, the bottom temperature is 183.3°C, the top pressure is 100 kPa, and the bottom pressure is 150 kPa.

[0113] The bottom of the tower produces 100 kg / h of furfuryl alcohol with a mass concentration of 99.5%, and the recovery rate of furfuryl alcohol is >99.5%, which can be directly sold or used in downstream chemical production; the top of the tower produces 472 kg / h of ethyl acetate with a mass fraction of 92.1%, which can be recycled to the extraction tower for repeated use. This process consumes 0.4 tons of low-pressure steam per hour.

[0114] Example 8

[0115] In a liquid-liquid extraction tower with 5 theoretical plates, a furfuryl alcohol-water mixture with a flow rate of 1000 kg / h enters from the first plate, the mass fraction of furfuryl alcohol in the feed is 20%, and the extractant chloroform enters from the fifth plate with a flow rate of 500 kg / h. The temperature of the extraction tower is 30°C, and the operating pressure of the extraction tower is normal pressure. The mass concentration of furfuryl alcohol in the aqueous phase after extraction is less than 0.2%. The chloroform phase (i.e., the organic phase after extraction) then enters the distillation tower, the theoretical number of plates of the distillation tower is 30, the feed position of the mixture is 15, the reflux ratio is 2.5, the top temperature is 41.9°C, the bottom temperature is 172.4°C, the top pressure is 80 kPa, and the bottom pressure is 109 kPa.

[0116] The bottom of the tower produces 200 kg / h of furfuryl alcohol with a mass concentration of 99.2%, and the recovery rate of furfuryl alcohol is >99.12%, which can be directly used for sales or downstream chemical production; the top of the tower produces 507 kg / h of chloroform with a mass fraction of 97%. This process consumes 0.3 tons of low-pressure steam per hour.

[0117] Example 9

[0118] In a liquid-liquid extraction tower with 5 theoretical plates, a furfuryl alcohol-water mixture with a flow rate of 1000 kg / h enters from the first plate, the mass fraction of furfuryl alcohol in the feed is 20%, and the extractant is the recycled chloroform containing 3wt% of water extracted from the bottom of the tower in Example 6. It enters the extraction tower from the fifth plate, with a flow rate of 500 kg / h, a temperature of the extraction tower of 25°C, and an operating pressure of the extraction tower of 150 kPa. The mass concentration of furfuryl alcohol in the aqueous phase after extraction is less than 0.6%, and can be directly fed into the sewage treatment device. The chloroform phase then enters the distillation tower, the theoretical number of plates of the distillation tower is 30, the feed position of the mixture is 15, the reflux ratio is 1.7, the top temperature is 42.1°C, the bottom temperature is 172°C, the top pressure is 80 kPa, and the bottom pressure is 109 kPa.

[0119] The bottom of the tower produces 197 kg / h of furfuryl alcohol with a mass concentration of 99.4%, and the recovery rate of furfuryl alcohol is >99.4%, which can be sold directly; the top of the tower produces 492 kg / h of chloroform with a mass fraction of 96.5%, which can be supplemented with 8 kg of fresh chloroform and then recycled to the extraction tower for repeated use, that is, only 8 kg of chloroform needs to be supplemented for every 1000 kg of wastewater. This process consumes 0.25 tons of low-pressure steam per hour.

[0120] Embodiment 10:

[0121] The operation is the same as that of Example 6, except that the flow rate of the extractant is 1000 kg / h and the extractant is a mixture of methyl isobutyl ketone: chloroform: water in a mass ratio of 39:58:3.

[0122] The concentration of furfuryl alcohol in the aqueous phase after extraction is less than 0.01%; 200 kg / h of furfuryl alcohol with a concentration of more than 99.7% is produced from the distillation tower kettle, and the recovery rate of furfuryl alcohol is greater than 99.9%; a mixture of extractants with a mass ratio of methyl isobutyl ketone: chloroform: water of 39:58:3 is produced from the top of the tower, and 4 kg of fresh chloroform and 6 kg of methyl isobutyl ketone can be supplemented and circulated to the extraction tower for repeated use. This process consumes 0.73 tons of low-pressure steam per hour.

[0123] Embodiment 11:

[0124] In a liquid-liquid extraction tower with 5 theoretical plates, a furfuryl alcohol-water mixture with a flow rate of 1000kg / h enters from the first plate, the mass fraction of furfuryl alcohol in the feed is 20%, and the extractant o-xylene enters the extraction tower from the fifth plate, with a flow rate of 1000kg / h, the extraction tower temperature is 30°C, and the operating pressure of the extraction tower is 150kPa. The mass concentration of furfuryl alcohol in the extracted water phase is less than 0.01%, and it can directly enter the sewage treatment device. The o-xylene phase then enters the distillation tower, the theoretical number of plates of the distillation tower is 30, the feed position of the mixture is 15, the reflux ratio is 1.5, the top temperature is 59°C, the bottom temperature is 178°C, the top pressure is 100kPa, and the bottom pressure is 129kPa.

[0125] The bottom of the tower produces 200 kg / h of furfuryl alcohol with a mass concentration of 99.9%, and the recovery rate of furfuryl alcohol is >99.9%, which can be sold directly; the top of the tower produces 1007 kg / h of o-xylene with a mass fraction of 99.3%, which can be supplemented with 1.3 kg of fresh o-xylene and then recycled to the extraction tower for repeated use, that is, only 1.3 kg of o-xylene is needed for every 1000 kg of wastewater. This process consumes 0.75 tons of low-pressure steam per hour.

[0126] Embodiment 12:

[0127] A kind of Figure 2 The furfuryl alcohol recovery device shown comprises an extractant storage tank 7, an extraction tower 1, a distillation tower 2, a compressor 3, a heat exchanger 4 and a first separator 5 which are connected in sequence;

[0128] The first separator 5 is also connected to the distillation tower 2 through a pipeline;

[0129] The heat exchanger 4 is also connected to the distillation tower 2 through a pipeline;

[0130] The first separator 5 is connected to the extractant storage tank 7 through a pipeline;

[0131] A second separator 6 is connected between the distillation tower 2 and the heat exchanger 4. That is, the heat exchanger 4 is connected to the distillation tower 2 through a pipeline. In addition, the distillation tower 2, the second separator 6 and the heat exchanger 4 are also connected in sequence through pipelines. Figure 2 The recovery method of furfuryl alcohol of the device shown is:

[0132] In a liquid-liquid extraction tower 1 having 5 theoretical plates, a furfuryl alcohol-water mixture (i.e., wastewater containing furfuryl alcohol) with a flow rate of 1000 kg / h enters from the first plate, the mass fraction of furfuryl alcohol in the feed is 20%, and the extractant o-xylene enters the extraction tower from the fifth plate with a flow rate of 1000 kg / h. The temperature of the extraction tower is 30° C., and the operating pressure of the extraction tower is 100 kPa. The mass concentration of furfuryl alcohol in the aqueous phase 13 after extraction is less than 0.01%, and can be directly fed into a sewage treatment device.

[0133] The organic phase 12 separated from the extraction tower 1 then enters a distillation tower having a theoretical plate number of 30, a mixture feed position of 15, a reflux ratio of 1.5, a top temperature of 142°C, a bottom temperature of 178°C, a top pressure of 100 kPa, and a bottom pressure of 129 kPa.

[0134] The overhead steam 15 extracted from the top of the distillation tower enters the compressor 3 to increase the pressure and temperature to obtain steam 21 (i.e., the overhead steam after the pressure increase) (its pressure is 400 kPa and the temperature is 215°C). The steam 21 then enters the heat exchanger 4 to be cooled to 181°C. The obtained condensate 16 (i.e., the overhead steam condensate 16) is separated into the overhead reflux liquid 17 and the reused extractant 18 by the separator 5. The overhead reflux liquid 17 is refluxed to the top of the distillation tower, and the overhead reflux is refluxed to the top of the distillation tower. The flow rate of liquid 17 is 1870 kg / h; the recycled extractant 18 is circulated to the extractant storage tank 7, and after being supplemented with fresh extractant, it enters the extraction tower for recycling; after the bottom produced liquid 22 passes through the second separator 6, a part of the produced liquid enters from the pipe side of the heat exchanger 4, and is heated into steam 23 (i.e., bottom reflux steam 23) in the heat exchanger 4, and the steam 23 is refluxed to the distillation tower with a flow rate of 92 kg / h; the remaining produced liquid 20 is produced as the furfuryl alcohol product.

[0135] The mass concentration of organic matter in the aqueous phase after extraction is lower than 0.05%; 200kg / h of furfuryl alcohol with a mass concentration higher than 99.3% is produced from the distillation tower kettle, and the recovery rate of furfuryl alcohol is>99%; all of the o-xylene with a mass concentration of 99.2% produced from the top of the tower is recycled to the extraction tower for repeated use, and only 1.5kg of fresh o-xylene as the extractant needs to be added per hour.

[0136] This embodiment utilizes the condensation latent heat of the tower top steam to heat the tower bottom reboiler, which greatly reduces the energy consumption required for the process, and consumes only 0.19 tons of low-pressure steam per hour. Compared with Comparative Example 1, the steam consumption is reduced by about 3.51 tons, saving 95% energy; compared with Example 11, the steam consumption is reduced by about 0.56 tons, saving 75% energy.

[0137] This embodiment consumes low steam and produces high quality furfuryl alcohol products, and requires little fresh o-xylene to be supplemented.

[0138] Comparative Example 1:

[0139] The flow rate of furfuryl alcohol-water mixture (i.e. furfuryl alcohol wastewater) is 1000kg / h, the mass fraction of furfuryl alcohol is 20%, and the flow rate is 1000kg / h. The total theoretical number of plates of the distillation tower is 30, the reflux ratio is 3, the top temperature is 99°C, the bottom temperature is 116°C, the furfuryl alcohol wastewater enters the distillation tower from the 30th plate, the top pressure is 100kPa, and the bottom pressure is 159kPa.

[0140] The bottom of the tower produces 200 kg / h of furfuryl alcohol with a mass concentration of 80.9%, and the recovery rate of furfuryl alcohol is 80.9%; the top of the tower produces 800 kg / h of aqueous solution with a furfuryl alcohol concentration of 4.8%. This separation process tower consumes 3.7 tons of low-pressure steam per hour.

[0141] The above is an exemplary description of the embodiments of the present invention. However, the protection scope of the present invention is not limited to the above embodiments. Any modification, equivalent substitution, improvement, etc. made by those skilled in the art within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for recovering furfuryl alcohol, characterized in that, The method comprises the following steps: (1) mixing an aqueous solution containing furfuryl alcohol with an extractant to perform extraction to obtain an extracted aqueous phase and an organic phase; (2) The organic phase obtained in step (1) is subjected to rectification and separation to obtain furfuryl alcohol.

2. The method according to claim 1, characterized in that In step (1), the extractant is selected from one, two or more of acetone, tetrahydrofuran, methyl ethyl ketone, n-butanol, ethyl acetate, ether, isopropyl ether, dichloromethane, chloroform, ethyl bromide, benzene, xylene, carbon tetrachloride, cyclohexane, hexane, n-heptane, methyl isobutyl ketone and o-xylene. Preferably, in step (1), the mass concentration of furfuryl alcohol in the aqueous solution containing furfuryl alcohol is greater than 0.1%. Preferably, in step (1), the mass ratio of the extractant to the aqueous solution containing furfuryl alcohol is 10:1 to 1:

10.

3. The method according to claim 1 or 2, characterized in that: In step (1), the extraction temperature is 5 to 50°C. Preferably, in step (1), the extraction is carried out in an extraction tower. Preferably, in step (2), distillation separation is carried out in a distillation tower. Preferably, the operating pressure of the distillation tower is 50-500 kPa, the operating temperature of the distillation tower is 50-200° C.; and the reflux ratio of the distillation tower is 0.1-10. Preferably, the method further comprises step (3): recycling the separated extractant and reusing it in step (1) to mix with furfuryl alcohol wastewater.

4. The method according to claim 3, characterized in that A condenser (8) is also provided between the extraction tower (1) and the distillation tower (2), and the condenser is used to heat the organic phase (12) from the top of the extraction tower and cool the top steam (15) from the distillation tower to obtain the preheated organic phase (14) and the top steam condensate (16). Preferably, a first separator (5) is connected between the condenser and the distillation tower; the tower top steam condensate (16) is separated in the first separator (5) to obtain tower top reflux liquid (17) and recycled extractant (18). Preferably, the recycled extractant (18) re-enters the extraction tower 1 as a partial replacement for the raw extractant. Preferably, the top reflux liquid (17) enters a distillation tower. Preferably, the extractant is stored in an extractant storage tank (7). Preferably, the first separator (5) is also connected to an extractant storage tank via a pipeline; the recycled extractant is sent to the extractant storage tank.

5. The method according to claim 3, characterized in that: The distillation tower (2) is also connected in sequence to a compressor (3), a heat exchanger (4) and a first separator (5). Preferably, the first separator is also connected to the distillation tower via a pipeline. Preferably, the heat exchanger (4) is also connected to the distillation tower via a pipeline. Preferably, the extractant is stored in an extractant storage tank. Preferably, the first separator (5) is connected to the extractant storage tank via a pipeline. Preferably, a second separator (6) is connected between the distillation tower and the heat exchanger. Preferably, the bottom of the distillation tower is connected to the bottom of the heat exchanger and the second separator (6) in sequence. Preferably, the method further comprises step (4): directly selling the separated furfuryl alcohol or using it for the production of furfuryl alcohol downstream chemicals.

6. A recovery device, the device being used to implement the method according to any one of claims 1 to 5, characterized in that: The device comprises: An extraction tower and a distillation tower, wherein the distillation tower is connected to the extraction tower; The extraction tower at least comprises an inlet for an aqueous solution containing furfuryl alcohol and an inlet for an extractant.

7. The device according to claim 6, characterized in that The extraction tower is a packed tower or a plate tower, the number of theoretical plates is 1 to 10, and the operating pressure is 50 to 500 kPa. Preferably, the temperature of the extraction tower is 5-50°C. Preferably, the inlet for the aqueous solution containing furfuryl alcohol is located at the upper part of the extraction tower, and the inlet for the extractant is located at the lower part of the extraction tower.

8. The device according to claim 6, characterized in that The top of the distillation tower is used to recover the extractant, and the bottom of the distillation tower is used to recover furfuryl alcohol. Preferably, the top of the distillation tower is also connected to the extractant inlet of the extraction tower.

9. The device according to claim 6, characterized in that A condenser (8) is also provided between the extraction tower (1) and the distillation tower (2), and the condenser is used to heat the organic phase (12) from the top of the extraction tower and cool the top steam (15) from the distillation tower to obtain the preheated organic phase (14) and the top steam condensate (16). Preferably, a first separator (5) is further connected between the condenser (8) and the distillation tower (2); the tower top steam condensate (16) is separated in the first separator (5) to obtain tower top reflux liquid (17) and recycled extractant (18). Preferably, the recycled extractant re-enters the extraction column as a partial replacement for the raw material extractant; Preferably, the top reflux liquid (17) enters a distillation tower. Preferably, the extractant is stored in an extractant storage tank (7). Preferably, the first separator (5) is also connected to the extractant storage tank (7) via a pipeline, and the recycled extractant is sent to the extractant storage tank.

10. The device according to claim 6, characterized in that The distillation tower (2) is also connected in sequence to a compressor (3), a heat exchanger (4) and a first separator (5). Preferably, the first separator is also connected to the distillation tower via a pipeline. Preferably, the heat exchanger is also connected to the distillation tower via a pipeline. Preferably, the extractant is stored in an extractant storage tank (7). Preferably, the first separator (5) is connected to the extractant storage tank (7) via a pipeline. Preferably, a second separator (6) is connected between the distillation tower (2) and the heat exchanger (4). Preferably, the bottom of the distillation tower is connected to the bottom of the heat exchanger (4) and the second separator (6) in sequence.

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