Devolatilizer and method for removing small molecular substances in polyether polyol and reducing odor

Abstract

The present invention provides a devolatilizer and method for removing small molecular substances in polyether polyol and reducing odor. The devolatilizer comprises: an upper devolatilizer and a lower devolatilizer, wherein the upper devolatilizer is provided with a first packing layer at the top, a second packing layer at the bottom, a steam distributor in the middle, a steam inlet, a first nitrogen distributor and a first nitrogen inlet below the second packing layer, a first polyether polyol distributor and a first feed port above the first packing layer, a first gas outlet at the top, and a first discharge port at the bottom; and the lower devolatilizer is provided with at least one third packing layer, a second polyether polyol distributor above the third packing layer, a second nitrogen distributor and a second nitrogen inlet below the third packing layer, a second gas outlet at the top, and a second discharge port at the bottom. In the devolatilizer of the present invention, no other components need to be introduced, and small organic molecules generated by side reactions can be removed, and odor can be reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of refined polyether polyols, and specifically relates to a devolatilizer and method for removing small molecular substances such as aldehydes and ketones generated in the production of polyether polyols and reducing odor at the same time. Background Art

[0002] Polyether polyol is an important raw material for the polyurethane industry, which is obtained by the polyaddition reaction of an initiator with propylene oxide and ethylene oxide under the action of a catalyst. It is widely used in furniture and home appliances such as refrigerators and sofas, interior decoration of aircraft and automobiles, as well as polyurethane waterproof coatings, adhesives, plastic runways and other fields, and has penetrated into all aspects of life. In the process of producing polyether polyols, due to the occurrence of side reactions, some small molecular substances such as aldehydes and ketones will be produced. Although the content of such odorous substances is relatively small, when polyether polyols are used as raw materials to produce the desired products, they will also cause the products to have a pungent odor.

[0003] With the improvement of people's quality of life and the increasing requirements for health and safety, more stringent requirements are also put forward for product quality. The volatile and high-odor organic matter in polyether polyols has become a key factor affecting the market share of products. Therefore, removing small molecules from polyether polyols has become an important way to enhance product competitiveness and expand the market.

[0004] The odor in polyether polyols mainly comes from the following aspects: (1) a small amount of odorous impurities carried in the product raw materials; (2) the side reactions during the propylene oxide reaction that cause the reaction to generate aldehydes; (3) ketone aldehyde compounds generated by polyether disproportionation rearrangement or oxidation by air. Common removal methods include ion adsorption, adding chemical substances to inhibit the generation of small molecular substances, nitrogen bubbling, etc. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a devolatilizer and method which can remove organic small molecules such as aldehydes and ketones produced by side reactions in polyether polyols and reduce odor by physical methods without introducing other components.

[0006] According to a first aspect of the present invention, there is provided a devolatilizer comprising:

[0007] Upper devolatilizer and lower devolatilizer,

[0008] A first packing layer located at the upper part and a second packing layer located at the lower part are arranged in the upper devolatilizer; a steam distributor and a steam inlet for supplying steam are arranged between the first packing layer and the second packing layer; a first nitrogen distributor and a first nitrogen inlet for supplying nitrogen are arranged below the second packing layer; a first polyether polyol distributor and a first feed inlet for supplying polyether polyol are arranged above the first packing layer; a first gas outlet is arranged at the top of the upper devolatilizer, and a first discharge port is arranged at the bottom of the upper devolatilizer;

[0009] At least one third packing layer is arranged in the lower devolatilizer, and a second polyether polyol distributor is arranged above the third packing layer, which is connected with the first discharge port through a second feed port to feed the polyether polyol purified by the upper devolatilizer from the first discharge port; a second nitrogen distributor and a second nitrogen inlet for supplying nitrogen are arranged below the third packing layer; a second gas outlet is arranged at the top of the lower devolatilizer, and a second discharge port is arranged at the bottom of the lower devolatilizer,

[0010] During operation, a polyether polyol liquid phase exists at the bottom of the upper devolatilizer and the lower devolatilizer, and the first nitrogen distributor and the second nitrogen distributor are respectively located below the liquid surface of the polyether polyol liquid phase.

[0011] Preferably, the fillers in the first packing layer, the second packing layer and the third packing layer are the same or different, and are independently random packing or structured packing, and the specific surface area of ​​the filler is 80 to 500 m 2 / m 3 , preferably 80~350m 2 / m 3 .

[0012] Preferably, the height of the first packing layer is 3D to 15D (D is the tower diameter), preferably 3D to 8D; the height of the second packing layer is 3D to 15D, preferably 3D to 8D; the height of the third packing layer is 0.5D to 8D, preferably 1D to 5D.

[0013] Preferably, the diameter ratio between the lower devolatilizer and the upper devolatilizer is 1-2.

[0014] Preferably, a wire mesh demister is provided before the first gas outlet and the second gas outlet, more preferably an SP type wire mesh demister, and further preferably, the specific surface area of ​​the wire mesh demister is 100 to 800 m 2 / m 3 .

[0015] Preferably, the first nitrogen distributor and the second nitrogen distributor are each independently a single-layer or multi-layer tubular distributor.

[0016] Preferably, the upper devolatilizer and the lower devolatilizer are integrated. Preferably, the upper devolatilizer is located above the lower devolatilizer. The material in the upper devolatilizer enters the lower devolatilizer by gravity and pressure difference.

[0017] Preferably, the devolatilizer further comprises: a product delivery pump, which is connected to the second discharge port to discharge the purified product; a first vacuum unit, which is connected to the first gas outlet to discharge the gas discharged from the upper devolatilizer; and a second vacuum unit, which is connected to the second gas outlet to discharge the gas discharged from the lower devolatilizer. Preferably, the first nitrogen inlet is connected to the second vacuum unit and the nitrogen source respectively so that a part of the gas discharged from the second gas outlet of the lower devolatilizer is combined as recycled gas and fresh nitrogen and enters the upper devolatilizer through the first nitrogen inlet.

[0018] In the present invention, the first feed port is communicated with the first polyether polyol distributor through a pipeline, so that the polyether polyol fed through the first feed port enters the first polyether polyol distributor. The steam inlet is communicated with the steam distributor through a pipeline, so that the steam fed through the steam inlet enters the steam distributor. The first nitrogen inlet is communicated with the first nitrogen distributor through a pipeline, so that the nitrogen fed through the first nitrogen inlet enters the first nitrogen distributor. The second feed port is communicated with the second polyether polyol distributor through a pipeline, so that the polyether polyol fed through the second feed port enters the second polyether polyol distributor. The second nitrogen inlet is communicated with the second nitrogen distributor through a pipeline, so that the nitrogen fed through the second nitrogen inlet enters the second nitrogen distributor.

[0019] According to a second aspect of the present invention, there is provided a method for removing small organic molecules from polyether polyols and reducing odor, the method using the devolatilizer according to the present invention and comprising the following steps:

[0020] The polyether polyol to be treated is continuously fed into the upper devolatilizer through the first feed port and the first polyether polyol distributor, and steam is fed from the steam inlet and nitrogen is fed from the first nitrogen inlet and the second nitrogen inlet at the same time; wherein the polyether polyol to be treated sequentially enters the first packing layer and contacts with steam and nitrogen for mass transfer, enters the second packing layer and contacts with nitrogen for mass transfer, then enters the third packing layer through the first discharge port, the second feed port and the second polyether polyol distributor and contacts with nitrogen for mass transfer, and then is discharged from the second discharge port of the lower devolatilizer to obtain the purified polyether polyol; and the gas carrying small molecular substances is discharged from the first gas outlet and the second gas outlet.

[0021] In the first packing layer, the polyether polyol contacts with steam and nitrogen for mass transfer. The steam inhibits the generation of small molecules and strengthens the small molecules dissolved in the polyether polyol. The nitrogen passes through the polyether polyol and brings out the small molecules in the polyether polyol during the rising process.

[0022] In the second packing layer, the polyether polyol contacts with nitrogen for mass transfer. The nitrogen passes through the polyether polyol and brings out small molecular substances in the polyether polyol during the rising process.

[0023] In the third packing layer, the polyether polyol contacts with nitrogen for mass transfer. The nitrogen passes through the polyether polyol and brings out small molecular substances in the polyether polyol during the rising process.

[0024] Preferably, the temperature of the polyether polyol to be treated is 100-180° C., preferably 120-170° C., and the operating pressure of the upper devolatilizer is controlled at 2-30 kPaA, preferably 5-25 kPaA.

[0025] If the feed temperature of polyether polyol is too low, it is difficult to achieve the purpose of small molecule removal, and if the temperature is too high, the formation of small molecule aldehydes and ketones will increase.

[0026] Preferably, the steam is saturated or superheated steam of 0.2 to 1.5 MPaG.

[0027] Preferably, the gas-liquid mass ratio of the polyether polyol to steam is in the range of 15-40.

[0028] Preferably, a bottom liquid phase is formed at the bottom of the upper devolatilizer, and the residence time of the bottom liquid phase is 1 to 15 minutes, preferably 1 to 10 minutes.

[0029] Preferably, the outlet flow rate of the first nitrogen distributor is between 2 and 50 m / s, preferably between 5 and 30 m / s.

[0030] Preferably, in the first nitrogen distributor, the gas-liquid volume ratio of the feed nitrogen to the polyether polyol is controlled in the range of 2-100, preferably 5-60.

[0031] Preferably, the temperature of the polyether polyol entering the lower devolatilizer through the first discharge port is 100-180°C, preferably 120-170°C.

[0032] Preferably, the operating pressure of the lower devolatilizer is 0.1 to 5 kPaA, preferably 0.5 to 2 kPaA.

[0033] Preferably, a bottom liquid phase is formed at the bottom of the lower devolatilizer, and the residence time of the bottom liquid phase is 1 to 15 minutes, preferably 1 to 10 minutes.

[0034] Preferably, the outlet flow rate of the second nitrogen distributor is between 2 and 50 m / s, preferably between 5 and 30 m / s.

[0035] Preferably, in the second nitrogen distributor, the gas-liquid volume ratio of the feed nitrogen to the polyether polyol is controlled in the range of 2-70, preferably 8-50.

[0036] Preferably, part of the gas discharged from the second gas outlet of the lower devolatilizer is combined with fresh nitrogen as recycled gas and then enters the upper devolatilizer through the first nitrogen inlet.

[0037] The advantages of the present invention are:

[0038] In the process of devolatilizing polyether polyols using the method according to the present invention, only non-toxic and harmless steam and nitrogen are introduced, and no additional impurities are introduced into the product. The process has the advantages of being simple, efficient, and highly adaptable. For polyether polyols of different grades prepared by different production processes, it can achieve the purpose of removing small molecular substances and odors. By adopting a continuous devolatilization process, steam and nitrogen are added in stages between different filler layers, so that the removal of small molecular aldehydes and ketones and other impurities in polyether polyols is more efficient and thorough, the product odor is significantly reduced, and finally a high-quality product is obtained. The use of upper and lower integrated devolatilizers not only saves space, but also reduces pipeline and equipment investment through equipment strengthening. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 The present invention is a schematic flow diagram of a method for removing small molecular substances using an integrated devolatilizer according to an embodiment of the present invention.

[0040] Reference numerals

[0041] I: Upper devolatilizer

[0042] II: Lower Devolatilizer

[0043] N1: First feed port

[0044] N2: First gas outlet

[0045] N3: Steam inlet

[0046] N4: First nitrogen inlet

[0047] N5: First outlet

[0048] N6: Second feeding port

[0049] N7: Second nitrogen inlet

[0050] N8: Second gas outlet

[0051] N9: Second discharge port

[0052] a: The first packing layer

[0053] b: The second packing layer

[0054] c: The third packing layer

[0055] d: Wire mesh demister

[0056] e: The first polyether polyol distributor

[0057] f: Steam distributor

[0058] g: First nitrogen distributor

[0059] h: Second polyether polyol distributor

[0060] i: Second nitrogen distributor

[0061] FIC: Flow Indicator Controller

[0062] LIC: Liquid Level Display Controller

[0063] PIC: Pressure display controller. DETAILED DESCRIPTION

[0064] Based on the technical solution of the present invention, combined with Figure 1 And specific implementation examples are provided to further illustrate the specific implementation methods and operation processes of the present invention.

[0065] Example 1

[0066] The integrated devolatilizer comprises an upper devolatilizer I, a lower devolatilizer II, a vacuum unit I (a first vacuum unit), a vacuum unit II (a second vacuum unit) and a product delivery pump.

[0067] The polyether polyol to be treated at 120°C containing small molecular substances such as aldehydes and ketones enters the upper devolatilizer I from the first feed port N1 at a flow rate of 10 t / h. The diameter of the upper devolatilizer is 700 mm and the control pressure is 25 kPaA. The high-temperature polyether polyol enters the first polyether polyol distributor (which is a tubular liquid distributor) e through the first feed port N1 and enters the first packing layer a after distribution. The first packing layer a is equipped with random packing with a specific surface area of ​​100 m 2 / m 3, the height of the first packing layer a is 4500mm. Fresh steam enters the upper devolatilizer I through the steam inlet N3 at a flow rate of 400kg / h (1MPaG) and after being distributed by the steam distributor f, the steam distributor f is located between the first packing layer a and the second packing layer b. The first packing layer a has a large specific surface area, the steam and the polyether polyol are fully in contact in the first packing layer a, gas-liquid mass transfer occurs, and the added steam can inhibit the generation of aldehydes and ketones, which has the effect of strengthening the removal of small molecular substances such as aldehydes and ketones dissolved in the polyether polyol.

[0068] Then the polyether polyol liquid is collected and redistributed at the bottom of the first packing layer a and then enters the second packing layer b, whose height is 4500mm. The second packing layer b is filled with random packing with a specific surface area of ​​100m 2 / m 3 The bottom liquid volume of the upper devolatilizer I is 1m 3 (residence time is 6 minutes), a nitrogen feeding system is provided below the liquid level, 60Nm 3 / h nitrogen (including recycled gas) enters the first nitrogen distributor (which is a ring pipe distributor) through the first nitrogen inlet N4 and is distributed, and then enters the bottom polyether polyol at a flow rate of 10m / s at the outlet. Nitrogen passes through the liquid surface in the form of bubbles, which can increase the gas-liquid contact interface to a certain extent and enhance mass transfer, and bring out aldehyde and ketone impurities in the bottom polyether polyol during the rising process.

[0069] The bottom nitrogen then enters the second packing layer b and the first packing layer a in turn, and transfers mass with the polyether polyol containing low concentration of aldehydes and ketones after steam stripping in the second packing layer b, so as to further remove aldehydes and ketones; in the first packing layer a, nitrogen and steam act as inert gases, and contact with the polyether polyol containing higher concentration on the packing surface, so as to cause gas-liquid mass transfer and reduce aldehyde and ketone impurities in the material.

[0070] After passing through the first packing layer a, the gas phase enters the gas phase space at the top of the upper devolatilizer I. In order to reduce the entrainment of mist at the gas phase outlet of the upper devolatilizer I, an SP type wire mesh demister d is provided before the first gas outlet N2. The specific surface area of ​​the wire mesh demister d is 400m 2 / m 3 The larger the specific surface area, the better the defoaming effect of the wire mesh, and the corresponding resistance drop will also increase.

[0071] Under the action of gravity and pressure difference, the polyether polyol at the bottom of the upper devolatilizer I flows out from the first outlet N5 of the upper devolatilizer I and enters the second polyether polyol distributor (which is a tubular liquid distributor) h through the second feed port N6 for distribution and then enters the third packing layer c of the lower devolatilizer II. At this time, the temperature of the polyether polyol from the upper devolatilizer I is about 120°C. The diameter of the lower devolatilizer II is 1000mm, and the pressure is controlled at 1kPaA. The third packing layer c is equipped with random packing, and the specific surface area of ​​the packing is 100m 2 / m 3 , its height is 1000mm.

[0072] The gas phase of the lower devolatilizer II enters the vacuum unit II from the second gas outlet N8 and is discharged as waste gas, or is mixed with fresh nitrogen after being pressurized by the unit and enters the upper devolatilizer.

[0073] The bottom liquid volume of the lower devolatilizer II is 1m 3 (residence time is 6 minutes), a nitrogen feeding system is provided below the liquid level, 5Nm 3 / h of nitrogen enters the second nitrogen distributor (which is a ring tube distributor) through the second nitrogen inlet N7 and is distributed, and then enters the bottom polyether polyol at a flow rate of 12m / s at the outlet. Nitrogen passes through the liquid surface in the form of bubbles, which can increase the gas-liquid contact interface and enhance mass transfer. The bottom nitrogen then rises and enters the third packing layer c, and deep removal of residual organic matter and moisture is achieved in the third packing layer c at a lower operating pressure, and finally a high-quality polyether polyol product with small molecular aldehydes and ketones and other impurities removed and product odor significantly reduced is obtained, and finally it is delivered to the product tank area through the product delivery pump. In addition, if Figure 1 As shown, a flow display controller FIC, a liquid level display controller LIC and a pressure display controller PIC are also provided in the devolatilizer to perform corresponding flow, level and pressure control.

[0074] The small molecule aldehydes and ketones / odor in the polyether polyols before and after removal were detected / evaluated. The test results are shown in Table 1.

[0075] Table 1: Aldehyde and ketone content (ppm) in the polyether polyol obtained in Example 1

[0076] formaldehyde Acetaldehyde acetone Propylene Ketone Odor Rating Before removal 50 110 25 40 3 After removal 0.3 15 0.1 0.3 1

[0077] It can be seen from the above that by adopting the process scheme for removing aldehyde and ketone impurities and reducing odor in polyether polyols described in the present invention, both the volatile components in polyether polyols and the product odor can be effectively reduced.

[0078] The content of aldehydes and ketones impurities was measured by gas chromatography.

[0079] The odor scoring was based on QB / T2725-2005 "Determination of Leather Odor", which is divided into 5 levels, as described below:

[0080] Level 1: No noticeable odor;

[0081] Level 2: Slight odor, but not noticeable;

[0082] Level 3: Obvious odor, but not offensive;

[0083] Level 4: Strong, unpleasant odor;

[0084] Level 5: Very strong unpleasant odor.

[0085] Example 2

[0086] The integrated devolatilizer comprises an upper devolatilizer I, a lower devolatilizer II, a vacuum unit I, a vacuum unit II and a product delivery pump.

[0087] The polyether polyol to be treated at 145°C containing small molecular substances such as aldehydes and ketones enters the upper devolatilizer I from the first feed port N1 at a flow rate of 20 t / h. The diameter of the upper devolatilizer is 1000 mm and the control pressure is 15 kPaA. The high-temperature polyether polyol enters the first polyether polyol distributor (which is a porous tube-type liquid distributor) e through the first feed port N1 and enters the first packing layer a after distribution. The first packing layer a is equipped with random packing with a specific surface area of ​​150 m 2 / m 3 The height of the first packing layer a is 5500 mm. Fresh steam enters the upper devolatilizer I through the steam inlet N3 at a flow rate of 600 kg / h and after being distributed by the steam distributor f, the steam distributor f is located between the first packing layer a and the second packing layer b. The first packing layer a has a large specific surface area, and the steam and the polyether polyol are fully contacted in the first packing layer a, gas-liquid mass transfer occurs, and the aldehyde and ketone impurities in the material are reduced.

[0088] Then the polyether polyol liquid is collected and redistributed at the bottom of the first packing layer a and then enters the second packing layer b, whose height is 5500mm. The second packing layer b is filled with random packing, and the specific surface area of ​​the packing is 80m 2 / m 3 The bottom liquid volume of the upper devolatilizer I is 2m 3 (residence time is 6 minutes), a nitrogen feeding system is provided below the liquid surface, 50Nm 3 / h nitrogen (including recycled gas) enters the first nitrogen distributor (which is a ring pipe distributor) through the first nitrogen inlet N4 and is distributed, and then enters the bottom polyether polyol at a flow rate of 15m / s at the outlet. Nitrogen passes through the liquid surface in the form of bubbles, which is beneficial to increase the gas-liquid contact interface and enhance mass transfer to a certain extent, and brings out aldehyde and ketone impurities in the bottom polyether polyol during the rising process.

[0089] The bottom nitrogen then enters the second packing layer b and the first packing layer a in turn, and transfers mass with the polyether polyol containing low concentration of aldehydes and ketones after steam stripping in the second packing layer b, so as to further remove aldehydes and ketones; in the first packing layer a, nitrogen and steam act as inert gases, and contact with the polyether polyol containing higher concentration on the packing surface, so as to cause gas-liquid mass transfer and reduce aldehyde and ketone impurities in the material.

[0090] The gas phase passes through the first packing layer a and enters the gas phase space at the top of the upper devolatilizer I. In order to reduce the entrainment of mist at the gas phase outlet of the upper devolatilizer I, a wire mesh demister d is provided before the first gas outlet N2. The specific surface area of ​​the wire mesh demister is 500m 2 / m 3 .

[0091] Under the action of gravity and pressure difference, the polyether polyol at the bottom of the upper devolatilizer I flows out from the first outlet N5 of the upper devolatilizer I and enters the second polyether polyol distributor (which is a tubular liquid distributor) h through the second feed port N6 for distribution and then enters the third packing layer c of the lower devolatilizer II. At this time, the temperature of the polyether polyol from the upper devolatilizer I is about 145°C. The diameter of the lower devolatilizer II is 1200mm, and the pressure is controlled at 1.5kPaA. The third packing layer c is equipped with random packing, and the specific surface area of ​​the packing is 80m 2 / m 3 , its height is 1500mm.

[0092] The gas phase of the lower devolatilizer II enters the vacuum unit II from the second gas outlet N8, and enters the upper devolatilizer I after being pressurized by the unit.

[0093] The bottom liquid volume of the lower devolatilizer II is 2m 3 (residence time is 6 minutes), a nitrogen feeding system is provided below the liquid level, 20Nm 3 / h of nitrogen enters the second nitrogen distributor (which is a ring tube distributor) i through the second nitrogen inlet N7 for distribution, and then enters the bottom polyether polyol at a flow rate of 8m / s at the outlet. Nitrogen passes through the liquid surface in the form of bubbles, which can increase the gas-liquid contact interface and enhance mass transfer. The bottom nitrogen then rises and enters the third packing layer c, and the residual organic matter and water are deeply removed in the third packing layer c at a lower operating pressure, and finally a high-quality polyether polyol product with impurities such as small molecular aldehydes and ketones removed and the product odor significantly reduced is obtained, and finally it is delivered to the product tank area through the product delivery pump.

[0094] The small molecule aldehydes and ketones / odor in the polyether before and after removal were detected / evaluated. The test results are shown in Table 2.

[0095] Table 2: Aldehyde and ketone content (ppm) in the polyether polyol obtained in Example 2

[0096] formaldehyde Acetaldehyde acetone Propylene Ketone Odor Rating Before removal 55 120 30 45 3 After removal 0.2 10 0.1 0.2 1

[0097] Comparative Example 1

[0098] After the reaction, the 145℃ polyether polyol containing aldehydes and ketones continuously enters the conventional devolatilization kettle from the upper space at a flow rate of 20t / h. The devolatilization kettle is equipped with a vacuum unit to maintain the pressure in the kettle at 1.5kPaA. The diameter of the devolatilization kettle is 1500mm and the height is 2500mm, of which the liquid phase volume is 4m 3 (Residence time is 12 minutes). A nitrogen feeding system is provided below the liquid surface, 20Nm 3 / h of nitrogen is distributed by the ring pipe distributor and enters the polyether polyol at the bottom at a flow rate of 8m / s at the outlet. During the rising process of the nitrogen, gas-liquid mass transfer occurs with the polyether polyol, which reduces the aldehyde and ketone impurities in the material to a certain extent.

[0099] The production system of this comparative example was used for treatment to detect / evaluate the small molecule aldehydes and ketones / odor in the polyether polyol before and after removal. The test results are shown in Table 3.

[0100] Table 3: Aldehyde and Ketone Content (ppm) in the Polyether Polyol Obtained in Comparative Example 1

[0101] formaldehyde Acetaldehyde acetone Propylene Ketone Odor Rating Before removal 55 120 30 45 3 After removal 25 85 23 35 2

[0102] It can be seen from the above that by adopting the process scheme for removing aldehyde and ketone impurities and reducing odor in polyether polyols described in the present invention, both the volatile components in polyether polyols and the product odor can be effectively reduced.

[0103] The above is only a preferred embodiment of the present invention. It should be pointed out that ordinary technicians in this field can make several improvements and supplements without departing from the method of the present invention. These improvements and supplements should also be regarded as the scope of protection of the present invention.

Claims

1. A devolatilizer, comprising: Upper devolatilizer and lower devolatilizer, Wherein, a first packing layer located at the upper part and a second packing layer located at the lower part are arranged in the upper devolatilizer; a steam distributor and a steam inlet for supplying steam are arranged between the first packing layer and the second packing layer; a first nitrogen distributor and a first nitrogen inlet for supplying nitrogen are arranged below the second packing layer; a first polyether polyol distributor and a first feed inlet for supplying polyether polyol are arranged above the first packing layer; a first gas outlet is arranged at the top of the upper devolatilizer, and a first discharge port is arranged at the bottom of the upper devolatilizer; At least one third packing layer is arranged in the lower devolatilizer, and a second polyether polyol distributor is arranged above the third packing layer, which is connected with the first discharge port through a second feed port to feed the polyether polyol purified by the upper devolatilizer from the first discharge port; a second nitrogen distributor and a second nitrogen inlet for supplying nitrogen are arranged below the third packing layer; a second gas outlet is arranged at the top of the lower devolatilizer, and a second discharge port is arranged at the bottom of the lower devolatilizer, During operation, a polyether polyol liquid phase exists at the bottom of the upper devolatilizer and the lower devolatilizer, and the first nitrogen distributor and the second nitrogen distributor are respectively below the liquid surface of the liquid phase of the polyether polyol. The upper devolatilizer and the lower devolatilizer are integrated.

2. The devolatilizer according to claim 1, wherein: The fillers in the first packing layer, the second packing layer and the third packing layer are the same or different, and are independently random packing or structured packing, and the specific surface area of ​​the fillers is 80 to 500 m 2 / m 3 .

3. The devolatilizer according to claim 2, wherein: The specific surface area of ​​the filler is 80 to 350 m 2 / m 3 .

4. The devolatilizer according to claim 1, wherein: The height of the first packing layer is 3 to 15 times the diameter of the upper devolatilizer; The height of the second packing layer is 3 to 15 times the diameter of the upper devolatilizer; The height of the third packing layer is 0.5 to 8 times the diameter of the lower devolatilizer; The diameter ratio of the lower devolatilizer to the upper devolatilizer is 1-2.

5. The devolatilizer according to claim 4, wherein: The height of the first packing layer is 3 to 8 times the diameter of the upper devolatilizer; and / or The height of the second packing layer is 3 to 8 times the diameter of the upper devolatilizer; and / or The height of the third packing layer is 1 to 5 times the diameter of the lower devolatilizer.

6. The devolatilizer according to claim 1, wherein: A wire mesh demister is arranged before the first gas outlet and the second gas outlet; The first nitrogen distributor and the second nitrogen distributor are each independently a single-layer or multi-layer tubular distributor.

7. The devolatilizer according to claim 6, wherein: The wire mesh demister is an SP type wire mesh demister.

8. The devolatilizer according to claim 7, wherein: The specific surface area of ​​the wire mesh demister is 100 to 800 m 2 / m 3 .

9. The devolatilizer according to any one of claims 1 to 8, wherein The devolatilizer further includes: a product delivery pump, which is connected to the second discharge port to discharge the purified product; a first vacuum unit, which is connected to the first gas outlet to discharge the gas discharged from the upper devolatilization tower; and a second vacuum unit, which is connected to the second gas outlet to discharge the gas discharged from the lower devolatilization tower.

10. The devolatilizer according to claim 9, wherein: The first nitrogen inlet is connected to the second vacuum unit and the nitrogen source through pipelines respectively so that part of the gas discharged through the second gas outlet of the lower devolatilizer is combined with fresh nitrogen as recycled gas and then enters the upper devolatilizer through the first nitrogen inlet.

11. A method for removing small organic molecules from polyether polyols and reducing odor, the method using the devolatilizer according to any one of claims 1 to 10, and comprising the following steps: The polyether polyol to be treated is continuously fed into the upper devolatilizer through the first feed port and the first polyether polyol distributor, and steam is fed from the steam inlet and nitrogen is fed to the first nitrogen inlet and the second nitrogen inlet at the same time, in, The polyether polyol to be treated sequentially enters the first packing layer and contacts with steam and nitrogen for mass transfer, enters the second packing layer and contacts with nitrogen for mass transfer, then enters the third packing layer through the first discharge port, the second feed port and the second polyether polyol distributor and contacts with nitrogen for mass transfer, and then is discharged from the second discharge port of the lower devolatilizer to obtain the purified polyether polyol; and the gas carrying small molecular substances is discharged from the first gas outlet and the second gas outlet.

12. The method according to claim 11, wherein: The temperature of the polyether polyol to be treated is 100-180° C., and the operating pressure of the upper devolatilizer is controlled at 2-30 kPaA; and / or The steam is saturated or superheated steam of 0.2-1.5 MPaG; and / or The gas-liquid mass ratio of the polyether polyol to the steam is in the range of 15-40.

13. The method according to claim 11, wherein: The temperature of the polyether polyol to be treated is 120-170° C.; and / or The operating pressure of the upper devolatilizer is controlled at 5-25 kPaA.

14. The method according to claim 11, wherein: A bottom liquid phase is formed at the bottom of the upper devolatilizer, and the residence time of the bottom liquid phase is 1 to 15 minutes; and / or The temperature of the polyether polyol entering the lower devolatilizer through the first discharge port is 100-180°C.

15. The method according to claim 14, wherein: A bottom liquid phase is formed at the bottom of the upper devolatilizer, and the residence time of the bottom liquid phase is 1 to 10 minutes; and / or The temperature of the polyether polyol entering the lower devolatilizer through the first discharge port is 120-170°C.

16. The method according to claim 11, wherein: The outlet flow rate of the first nitrogen distributor is between 2 and 50 m / s; and / or In the first nitrogen distributor, the gas-liquid volume ratio of the feed nitrogen to the polyether polyol is controlled in the range of 2-100.

17. The method according to claim 16, wherein: The outlet flow rate of the first nitrogen distributor is 5 to 30 m / s; and / or In the first nitrogen distributor, the gas-liquid volume ratio of the feed nitrogen to the polyether polyol is controlled in the range of 5-60.

18. The method according to any one of claims 11 to 17, wherein: The operating pressure of the lower devolatilizer is 0.1-5 kPaA; and / or A bottom liquid phase is formed at the bottom of the lower devolatilizer, and the residence time of the bottom liquid phase is 1 to 15 minutes; and / or The outlet flow rate of the second nitrogen distributor is between 2 and 50 m / s; and / or In the second nitrogen distributor, the gas-liquid volume ratio of the feed nitrogen to the polyether polyol is controlled in the range of 2 to 70; and / or A portion of the gas discharged from the second gas outlet of the lower devolatilizer is combined with fresh nitrogen as recycled gas and then enters the upper devolatilizer through the first nitrogen inlet.

19. The method according to claim 18, wherein: The operating pressure of the lower devolatilizer is 0.5-2 kPaA; and / or A bottom liquid phase is formed at the bottom of the lower devolatilizer, and the residence time of the bottom liquid phase is 1 to 10 minutes; and / or The outlet flow rate of the second nitrogen distributor is 5 to 30 m / s; and / or In the second nitrogen distributor, the gas-liquid volume ratio of the feed nitrogen to the polyether polyol is controlled in the range of 8-50.

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