Process and apparatus for recovering furfuryl alcohol

Abstract

This invention discloses a method and apparatus for recovering furfuryl alcohol. The method includes: (1) mixing an aqueous solution containing furfuryl alcohol with an extractant for extraction to obtain an aqueous phase and an organic phase after extraction; (2) separating the organic phase obtained in step (1) by distillation to obtain furfuryl alcohol. This invention employs a separation method combining extraction and distillation to achieve efficient recovery of low-concentration furfuryl alcohol, while the extractant can be recycled. This invention's method is simple, economical, and has good prospects for industrial application.

Description

Technical Field

[0001] This invention relates to a method and apparatus for recovering furfuryl alcohol, belonging to the field of furfuryl alcohol derivative production technology. Background Technology

[0002] Furfuryl alcohol, also known as 2-hydroxymethylfuran, is the most important downstream derivative of furfural. It accounts for approximately 65% ​​of global furfural processing products. China is the world's largest producer of furfuryl alcohol, with an annual global production exceeding 300,000 tons, 70% of which is produced in China. Furfuryl alcohol has a wide range of applications, primarily in resin production, in the metal casting industry for making high-performance core molds and metal dies, as a viscosity reducer for epoxy resins, and in the manufacture of polyurethane foams and polyester products. In addition, furfuryl alcohol can be used to synthesize fragrances and the anti-ulcer drug lanitidine, thus it is also widely used in the food and pharmaceutical industries.

[0003] Currently, domestic sources of furfuryl alcohol mainly include two processes: gas-phase hydrogenation and liquid-phase hydrogenation of furfural. During furfuryl alcohol production, a large amount of wastewater with a furfuryl alcohol concentration of 0.1–20 wt% is easily generated. This wastewater has a high COD value and cannot be directly discharged. However, if it is sent to wastewater treatment facilities, not only are the treatment costs high, but the furfuryl alcohol in it cannot be utilized, resulting in serious resource waste. Although furfuryl alcohol can be separated from the wastewater by distillation, this method consumes a huge amount of energy and has poor economic viability for industrial applications. Therefore, there is an urgent need to develop a furfuryl alcohol recovery method that is economical, environmentally friendly, and efficient. Summary of the Invention

[0004] To address the aforementioned technical problems, the present invention provides a method for recovering furfuryl alcohol, the method comprising the following steps:

[0005] (1) Mix an aqueous solution containing furfuryl alcohol with an extractant and extract to obtain an aqueous phase and an organic phase after extraction;

[0006] (2) The organic phase obtained in step (1) is separated by distillation 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 the following: acetone, tetrahydrofuran, methyl ethyl ketone, n-butanol, ethyl acetate, diethyl ether, isopropyl ether, dichloromethane, chloroform, bromoethane, 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), the mass concentration of furfuryl alcohol in the aqueous solution containing furfuryl alcohol is 0.1% or more, for example, 0.1% to 20%, such as 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 wastewater 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 theoretical number of plates in the extraction tower is 1 to 10, for example, 1, 2, 4, 5, 7, 9, or 10 plates. 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 top of the extraction column, and the extractant is fed from the bottom of the extraction column. More 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 extracted aqueous phase can be directly sent to a wastewater treatment device 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 column.

[0016] According to an embodiment of the present invention, in step (2), the distillation column can be a packed column or a plate column. Preferably, the distillation column is further connected to a total condenser and a reboiler. Preferably, the number of theoretical plates in the distillation column is 20 to 60. Preferably, the operating pressure of the distillation column 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 column is 50 to 200 °C. Preferably, the reflux ratio of the distillation column is 0.1 to 10.

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

[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 the distillation column, and furfuryl alcohol is obtained at the bottom of the distillation column.

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

[0020] According to an embodiment of the present invention, in step (2), the purity of the 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 includes 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 column 1 and the distillation column 2. The condenser 8 is used to heat the organic phase 12 from the top of the extraction column and cool the top vapor 15 from the distillation column to obtain the preheated organic phase 14 and the top vapor condensate 16.

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

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

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

[0026] Preferably, the recycled extractant 18 is reintroduced into the extraction tower 1 as a partial substitute for the raw material extractant;

[0027] Preferably, the reflux liquid 17 at the top of the column enters the distillation column.

[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. Reclaimed extractant is fed into the extractant storage tank.

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

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

[0032] According to an embodiment of the present invention, the heat exchanger 4 is also connected to a distillation column via 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 via a pipe.

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

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

[0037] The present invention also provides a recycling apparatus for implementing the above method, the apparatus comprising:

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

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

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

[0041] According to an embodiment of the present invention, the temperature of the extraction tower is 5 to 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 column is used to recover furfuryl alcohol.

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

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

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

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

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

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

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

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

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

[0053] Preferably, the steam comes from the top of the distillation column, 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 column 2; the top vapor condensate 16 is separated in the first separator 5 to obtain the top reflux liquid 17 and the recycled extractant 18.

[0055] Preferably, the recycled extractant 18 is reintroduced into the extraction tower 1 as a partial substitute for the raw material extractant;

[0056] Preferably, the reflux liquid 17 at the top of the column enters the distillation column.

[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. Reclaimed extractant is fed into the extractant storage tank.

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

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

[0061] According to an embodiment of the present invention, the heat exchanger is also connected to a distillation column via 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 via a pipe.

[0064] According to an embodiment of the present invention, a second separator 6 is connected between the distillation column 2 and the heat exchanger 4. Preferably, the bottom of the distillation column is connected to the heat exchanger and the second separator 6 in sequence. After part of the liquid drawn from the bottom of the distillation column is heated into steam in the heat exchanger, it flows back to the bottom of the distillation column to provide rising steam for the distillation column.

[0065] According to an embodiment of the present invention, the distillation column is used in the method for recovering furfuryl alcohol described in the present invention. Therefore, the method for recovering furfuryl alcohol described in the present invention further includes performing the above-described step (2) using the distillation column. Beneficial effects of the present invention:

[0066] This invention employs a separation method combining extraction and distillation to achieve efficient recovery of low-concentration furfuryl alcohol, while allowing for the recycling of the extractant. The method is simple, economical, and has promising prospects for industrial application. Specifically:

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

[0068] (2) The extractant used in this invention is inexpensive and can be recycled and reused, resulting in minimal 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 make full use of the steam at the top of the distillation column to heat the organic phase 12 from the top of the extraction column, making full use of the latent heat of condensation or waste heat in the process flow, which greatly reduces the energy consumption of the process flow and thus reduces the production cost.

[0071] (5) The method and apparatus of the present invention make full use of the steam at the top of the distillation column to heat the reboiler in the column bottom, thereby reducing the energy consumption required for the process and greatly reducing the production cost. Attached Figure Description

[0072] Figure 1 The diagrams are of the apparatus in Examples 4 and 6;

[0073] Figure 2 This is a diagram of the apparatus in Example 12;

[0074] Wherein: 1-Extraction column; 2-Distillation column; 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 effluent; 23-Bottom reflux steam. Detailed Implementation

[0075] The technical solution of the present invention will be further described in detail below with reference to specific embodiments. It should be understood that the following embodiments are merely illustrative and explanatory 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 covered within the scope of protection intended by the present invention.

[0076] Unless otherwise stated, the raw materials and reagents used in the following examples are commercially available products 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 HP-5 capillary column (30m×0.32μm, 0.25μm) and FID detector. The external standard method was used to detect the types of substances and the content of each substance.

[0078] Example 1:

[0079] A separation apparatus includes an extraction column and a distillation column, wherein the distillation column is connected to the extraction column;

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

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

[0082] In a liquid-liquid extraction column 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, with a furfuryl alcohol mass fraction of 20%. Pure methyl isobutyl ketone (Methyl isobutyl ketone) as the extractant enters from the fifth plate at a flow rate of 1000 kg / h. The extraction column temperature is 10°C, and the operating pressure is atmospheric pressure. The furfuryl alcohol mass concentration in the aqueous phase after extraction is less than 0.01%, and it can be sent to a wastewater treatment unit. The Methyl isobutyl ketone phase (i.e., the extracted organic phase) then enters a distillation column with 60 theoretical plates. The feed position of the extracted organic phase 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%, with a furfuryl alcohol recovery rate >99.9%, which can be sold directly 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] Example 2:

[0085] The operation is the same as in Example 1, except that the flow rate of the extractant, pure methyl isobutyl ketone, is 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 collected from the bottom of the distillation column, with a furfuryl alcohol recovery rate >99.9%; 527.375 kg / h of methyl isobutyl ketone with a mass fraction of 92.3% is collected from the top of the column. This process consumes 0.36 tons of low-pressure steam per hour.

[0087] Example 3:

[0088] In the apparatus used in this embodiment 3, the top of the distillation column 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 all the extractant obtained from the top of the distillation column is recycled back to the extraction column for reuse, and only 13.6 kg of fresh extractant methyl isobutyl ketone needs to be added every hour.

[0090] The 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 concentration higher than 99.9% is collected from the bottom of the distillation column, with a furfuryl alcohol recovery rate >99.9%. All methyl isobutyl ketone containing 7.6 wt% water collected from the top of the column is recycled back to the extraction column for reuse. This process consumes 0.28 tons of low-pressure steam per hour.

[0091] Example 4:

[0092] One such 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 connected in sequence.

[0093] A first separator 5 is also connected between the condenser 8 and the distillation column 2; that is, the condenser 8 and the distillation column 2 are connected by a pipe. In addition, the condenser 8, the first separator 5 and the distillation column 2 are also connected in sequence by various pipes.

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

[0095] The bottom of the distillation column 2 is equipped with a reboiler 9;

[0096] The top of the distillation column is also connected to an extractant storage tank (not shown in the figure). Using... Figure 1 The method for recovering furfuryl alcohol from the apparatus shown is as follows:

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

[0098] Organic phase 12 then enters condenser 8 and is preheated to 90°C by the overhead vapor 15 from distillation column 2. The preheated organic phase 14 enters distillation column 2. The condensate 16 after the vapor is cooled in condenser 8 enters separator and is separated into aqueous phase 17 and recycled extractant 18. The recycled extractant is reloaded into extractant storage tank 7, and the aqueous phase 17 separated in separator 5 is sent back to distillation column 2.

[0099] The methyl isobutyl ketone phase (i.e., the extracted organic phase) then enters a distillation column with 60 theoretical plates. The feed position of the extracted organic phase is 30, the reflux ratio is 1, the top temperature is 85.7℃, the bottom temperature is 185℃, the top pressure is 100 kPa, and the bottom pressure is 159 kPa. All the recycled extractant after separation in the distillation column is returned to the extractant storage tank and then reintroduced into the extraction column for reuse.

[0100] This thermal integration process consumes 0.18 tons of low-pressure steam per hour. Compared to Example 1, this reduces steam consumption by approximately 0.44 tons, resulting in energy savings of 71%; compared to Example 3, it reduces steam consumption by approximately 0.1 tons, resulting in energy savings of 36%.

[0101] The 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 concentration of more than 99.9% is collected from the bottom of the distillation column, with a furfuryl alcohol recovery rate of >99.9%. All of the methyl isobutyl ketone with a water content of 8.2 wt% collected from the top of the column is recycled back to the extraction column for reuse, and only 13.6 kg of fresh methyl isobutyl ketone needs to be added per hour.

[0102] Example 5:

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

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

[0105] Example 6

[0106] Adopting such Figure 1 The method for recovering furfuryl alcohol from the apparatus shown is as follows:

[0107] In a liquid-liquid extraction column 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%. The extractant 11-methyl isobutyl ketone enters from the fifth plate (the extractant comes from the recycled extractant and fresh extractant collected from the top of the distillation column, with a flow rate of 15.4 kg / h for the fresh extractant) with a flow rate of 500 kg / h. The temperature of the extraction column is 30°C, and the operating pressure of the extraction column is 100 kPa.

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

[0109] The methyl isobutyl ketone phase (i.e., the extracted organic phase) then enters a distillation column. Distillation column 2 has 30 theoretical plates, a feed position of 15, a reflux ratio of 2, a top temperature of 108.0°C, a bottom temperature of 183.3°C, a top pressure of 100 kPa, and a bottom pressure of 159 kPa. This embodiment consumes 0.15 tons of low-pressure steam per hour. Compared to Example 1, this reduces steam consumption by approximately 0.47 tons, resulting in energy savings of 76%; compared to Example 3, it reduces steam consumption by approximately 0.13 tons, resulting in energy savings of 46%.

[0110] The concentration of furfuryl alcohol in the aqueous phase 10 after extraction is less than 0.01%, and the concentration of methyl isobutyl ketone is less than 0.3%. 100 kg / h of furfuryl alcohol with a concentration of more than 99.9% is collected from the bottom of the distillation column, with a furfuryl alcohol recovery rate of >99.9%. 484.6 kg / h of methyl isobutyl ketone with a water content of 5.0 wt% is collected from the top of the column. All of it is recycled back to the extraction column for reuse. Only 15.4 kg of fresh methyl isobutyl ketone needs to be added every hour.

[0111] Example 7

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

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

[0114] Example 8

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

[0116] The bottom of the tower produces 200 kg / h of furfuryl alcohol with a mass concentration of 99.2%, with a furfuryl alcohol recovery rate of >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 column with 5 theoretical plates, a furfuryl alcohol-water mixture with a flow rate of 1000 kg / h enters from the first plate. The furfuryl alcohol mass fraction in the feed is 20%. The extractant is recycled chloroform containing 3 wt% water, collected from the bottom of the column in Example 6, entering the extraction column from the fifth plate at a flow rate of 500 kg / h. The extraction column temperature is 25°C, and the operating pressure is 150 kPa. The furfuryl alcohol mass concentration in the extracted aqueous phase is less than 0.6%, which can be directly fed into the wastewater treatment plant. The chloroform phase then enters a distillation column with 30 theoretical plates. The mixture feed position 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 extraction tower yields 197 kg / h of furfuryl alcohol with a mass concentration of 99.4%, achieving a furfuryl alcohol recovery rate of >99.4%, which can be sold directly. The top of the tower yields 492 kg / h of chloroform with a mass fraction of 96.5%, which can be replenished with 8 kg of fresh chloroform and recycled back to the extraction tower for reuse. This means that only 8 kg of chloroform is needed to replenish every 1000 kg of wastewater. This process consumes 0.25 tons of low-pressure steam per hour.

[0120] Example 10:

[0121] The operation is the same as in Example 6, except that the extractant flow rate 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 higher than 99.7% is collected from the bottom of the distillation column, achieving a recovery rate >99.9%. A mixture of methyl isobutyl ketone, chloroform, and water at a mass ratio of 39:58:3 is collected from the top of the column and can be recycled back to the extraction column after replenishing with 4 kg of fresh chloroform and 6 kg of methyl isobutyl ketone. This process consumes 0.73 tons of low-pressure steam per hour.

[0123] Example 11:

[0124] In a liquid-liquid extraction column with 5 theoretical plates, a furfuryl alcohol-water mixture with a flow rate of 1000 kg / h enters from the first plate, containing 20% ​​furfuryl alcohol by mass. The extractant, o-xylene, enters from the fifth plate at a flow rate of 1000 kg / h. The extraction column temperature is 30°C, and the operating pressure is 150 kPa. The furfuryl alcohol concentration in the extracted aqueous phase is less than 0.01%, allowing it to be directly fed into a wastewater treatment plant. The o-xylene phase then enters a distillation column with 30 theoretical plates. The mixture feed point is 15, the reflux ratio is 1.5, the top temperature is 59°C, the bottom temperature is 178°C, the top pressure is 100 kPa, and the bottom pressure is 129 kPa.

[0125] The bottom of the extraction tower yields 200 kg / h of furfuryl alcohol with a mass concentration of 99.9%, with a furfuryl alcohol recovery rate >99.9%, which can be sold directly. The top of the tower yields 1007 kg / h of o-xylene with a mass fraction of 99.3%, which can be replenished with 1.3 kg of fresh o-xylene and recycled back to the extraction tower for reuse. That is, only 1.3 kg of o-xylene needs to be added for every 1000 kg of wastewater. This process consumes 0.75 tons of low-pressure steam per hour.

[0126] Example 12:

[0127] One such Figure 2 The furfuryl alcohol recovery device shown includes an extractant storage tank 7, an extraction column 1, a distillation column 2, a compressor 3, a heat exchanger 4, and a first separator 5 connected in sequence.

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

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

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

[0131] A second separator 6 is connected between the distillation column 2 and the heat exchanger 4. Specifically, the heat exchanger 4 is connected to the distillation column 2 via a pipe. Furthermore, the distillation column 2, the second separator 6, and the heat exchanger 4 are sequentially connected via pipes. [The following sentence appears to be incomplete and requires further context: "Adopting..."] Figure 2 The method for recovering furfuryl alcohol from the apparatus shown is as follows:

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

[0133] The organic phase 12 separated from the extraction column 1 then enters the distillation column, which has 30 theoretical plates, a 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 vapor 15 collected from the top of the distillation column enters the compressor 3 for pressurization and heating, yielding vapor 21 (i.e., the pressurized overhead vapor) (its pressure is 400 kPa and its temperature is 215 °C). Vapor 21 then enters the heat exchanger 4 for cooling to 181 °C. The resulting condensate 16 (i.e., the overhead vapor condensate 16) is separated by the separator 5 into overhead reflux liquid 17 and recycled extractant 18. Overhead reflux liquid 17 is returned to the top of the distillation column. The flow rate of liquid 17 is 1870 kg / h; the recycled extractant 18 is circulated to the extractant storage tank 7, and after replenishing with fresh extractant, it enters the extraction tower for recycling; after passing through the second separator 6, a portion of the extracted liquid 22 enters from the tube side of the heat exchanger 4 and is heated into steam 23 (i.e., tower bottom reflux steam 23) in the heat exchanger 4, and the steam 23 is refluxed to the distillation tower at a flow rate of 92 kg / h; the remaining extracted liquid 20 is extracted as furfuryl alcohol product.

[0135] The organic matter concentration in the aqueous phase after extraction is less than 0.05%; 200 kg / h of furfuryl alcohol with a concentration higher than 99.3% is collected from the bottom of the distillation column, with a furfuryl alcohol recovery rate of >99%; all o-xylene with a concentration of 99.2% collected from the top of the column is recycled back to the extraction column for reuse, and only 1.5 kg of fresh o-xylene extractant needs to be added every hour.

[0136] This embodiment utilizes the latent heat of condensation of the overhead steam to heat the reboiler in the column, significantly reducing the energy consumption required for the process, consuming only 0.19 tons of low-pressure steam per hour. Compared to Comparative Example 1, this reduces steam consumption by approximately 3.51 tons, achieving energy savings of 95%; compared to Example 11, it reduces steam consumption by approximately 0.56 tons, achieving energy savings of 75%.

[0137] This embodiment consumes less steam, produces high-quality furfuryl alcohol, and requires less fresh o-xylene to replenish.

[0138] Comparative Example 1:

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

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

[0141] The embodiments of the present invention have been described above by way of example. However, the scope of protection of the present invention is not limited to the above embodiments. Any modifications, equivalent substitutions, improvements, etc., made by those skilled in the art within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for recovering furfuryl alcohol, characterized in that, The method includes the following steps: (1) The aqueous solution containing furfuryl alcohol was mixed with the extractant and extracted to obtain the aqueous phase and organic phase after extraction; (2) The organic phase obtained in step (1) is subjected to distillation to obtain furfuryl alcohol; In step (1), the extractant is at least one of methyl isobutyl ketone, n-butanol, ethyl acetate, chloroform, and o-xylene; In step (1), the mass concentration of furfuryl alcohol in the aqueous solution containing furfuryl alcohol is 10-20%. In step (1), the extraction is carried out in an extraction tower; The extraction temperature is 10-30℃, and the operating pressure of the extraction tower is atmospheric pressure -150kPa.

2. The method according to claim 1, characterized in that, 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, characterized in that, In step (2), distillation separation is carried out in a distillation column.

4. The method according to claim 1, characterized in that, The operating pressure of the distillation column is 50-500 kPa, the operating temperature of the distillation column is 50-200℃, and the reflux ratio of the distillation column is 0.1-10.

5. The method according to claim 1, characterized in that, The method further includes step (3): recycling the separated extractant and reusing it in step (1) to mix with furfuryl alcohol wastewater.

6. The method according to claim 3, characterized in that, A condenser (8) is provided between the extraction column (1) and the distillation column (2). The condenser is used to heat the organic phase (12) from the top of the extraction column and cool the top vapor (15) from the distillation column to obtain the preheated organic phase (14) and the top vapor condensate (16).

7. The method according to claim 6, characterized in that, A first separator (5) is also connected between the condenser and the distillation column; the top vapor condensate (16) is separated in the first separator (5) to obtain the top reflux liquid (17) and the recycled extractant (18).

8. The method according to claim 7, characterized in that, The recycled extractant (18) is reintroduced into the extraction tower (1) as a partial substitute for the raw material extractant.

9. The method according to claim 8, characterized in that, The reflux liquid (17) at the top of the column enters the distillation column.

10. The method according to claim 9, characterized in that, The extractant is stored in an extractant storage tank (7).

11. The method according to claim 10, characterized in that, The first separator (5) is also connected to the extractant storage tank via a pipeline; the recycled extractant is sent into the extractant storage tank.

12. The method according to claim 6, characterized in that, The distillation column (2) is also connected in sequence to the compressor (3), the heat exchanger (4) and the first separator (5); The first separator is also connected to a distillation column via a pipeline; The heat exchanger (4) is also connected to the distillation column via a pipeline.

13. The method according to claim 12, characterized in that, A second separator (6) is connected between the distillation column and the heat exchanger.

14. The method according to claim 13, characterized in that, The bottom of the distillation column is connected in sequence to the bottom of the heat exchanger and the second separator (6).

15. The method according to claim 5, characterized in that, Preferably, the method further includes step (4): selling the separated furfuryl alcohol directly or using it in the production of downstream chemicals of furfuryl alcohol.

16. A recycling apparatus, said apparatus for carrying out the method according to any one of claims 1-15, characterized in that, The device includes: An extraction column and a distillation column, wherein the distillation column is connected to the extraction column; The extraction tower includes at least an inlet containing an aqueous solution of furfuryl alcohol and an extractant inlet; The temperature of the extraction tower is 10-30℃, and the operating pressure of the extraction tower is atmospheric pressure - 150kPa.

17. The apparatus according to claim 16, characterized in that, The extraction tower is a packed tower or a plate tower, with a theoretical number of 1 to 10 plates.

18. The apparatus according to claim 16, characterized in that, The inlet of the aqueous solution containing furfuryl alcohol is located at the top of the extraction tower, and the inlet of the extractant is located at the bottom of the extraction tower.

19. The apparatus according to claim 16, characterized in that, The top of the distillation column is used to recover the extractant, and the bottom of the distillation column is used to recover furfuryl alcohol.

20. The apparatus according to claim 16, characterized in that, The top of the distillation column is also connected to the extractant inlet of the extraction column.

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

22. The apparatus according to claim 21, characterized in that, The distillation column (2) is also connected in sequence to the compressor (3), the heat exchanger (4) and the first separator (5); The first separator is also connected to a distillation column via a pipeline; The heat exchanger is also connected to the distillation column via a pipeline; The bottom of the distillation column is connected in sequence to the bottom of the heat exchanger (4) and the second separator (6).

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