CN116573703A - A kind of NMP dynamic rectification equipment and its control method - Google Patents

Abstract

The invention discloses NMP dynamic rectification equipment and a control method thereof, and relates to the technical field of NMP waste liquid treatment. In the present invention, the surface of the evaporator in the molecular distillation cylinder is provided with a creeping diffusion layer with a relatively large roughness, a radiation diffusion layer with a second roughness, and a relatively smooth moisture escape layer, and the roughness of the creeping diffusion layer and the radiation diffusion layer are both It is set to a state of linear decrease from top to bottom, which not only forms a strong solid-liquid surface energy when the waste liquid contacts the evaporation surface, but also "creeps" and slides down after being subjected to the gravity of the liquid itself, and spreads continuously, forming a top-down multiple Linearize the "loose" liquid state, and efficiently complete molecular distillation in the wet escape layer, thereby reducing the boiling phenomenon of waste liquid on the evaporation surface of the evaporator and improving the effect of falling film molecular distillation.

Description

A kind of NMP dynamic rectification equipment and its control method

technical field

The invention relates to the technical field of NMP waste liquid treatment, in particular to an NMP dynamic rectification equipment and a control method thereof.

Background technique

Molecular distillation is a special liquid-liquid separation technology. It is different from traditional distillation which relies on the separation principle of boiling point difference, but relies on the difference in the mean free path of molecular motion of different substances to achieve separation. When the liquid mixture flows along the heating plate and is heated, the light and heavy molecules will escape from the liquid surface and enter the gas phase. Since the free paths of the light and heavy molecules are different, the molecules of different substances move different distances after escaping from the liquid surface. If a condensing plate can be installed properly, the light molecules will reach the condensing plate and be condensed and discharged, while the heavy molecules will not reach the condensing plate and be discharged along the mixed liquid. In this way, the purpose of material separation is achieved. The pressure difference between the boiling film and the condensing surface is the driving force for the direction of steam flow, and a small pressure drop will cause the flow of steam.

NMP waste liquid is an industrial waste liquid whose main component can be recycled, and its recovery value is relatively high. When NMP waste liquid is separated and recovered, the recovery method of molecular distillation can greatly improve the recovery accuracy. Among the molecular distillation equipment, the centrifugal molecular distillation equipment has higher requirements on the overall sealing performance, structural cost, and use environment of the equipment. Although the falling film molecular distillation equipment has a simple structure, when the waste liquid just enters the evaporation surface of the evaporator, the liquid The flow rate is large, and a large amount of liquid is easy to roll on the evaporation surface of the evaporator, resulting in boiling phenomenon, which seriously affects the separation effect of molecular distillation of waste liquid. Therefore, in the process of molecular distillation of NMP waste liquid by using falling film molecular distillation equipment, reducing the boiling phenomenon of waste liquid on the evaporation surface of the evaporator and improving the effect of falling film molecular distillation have become problems that need to be solved.

Contents of the invention

The technical problem to be solved by the present invention is to provide an NMP dynamic rectification equipment and its control method, thereby reducing the boiling phenomenon of waste liquid on the evaporation surface of the evaporator and improving the effect of falling film molecular distillation.

In order to solve the problems of the technologies described above, the present invention is achieved through the following technical solutions:

The invention provides a kind of NMP dynamic rectification equipment, comprising a molecular distillation cylinder, the molecular distillation cylinder is connected with a vacuum pipeline, the molecular distillation cylinder is equipped with an evaporator with an evaporation surface, and the molecular distillation cylinder is equipped with a distributor located above the evaporator 1. A feed pipe connected to the distributor. A condenser is built in the molecular distillation cylinder. The condenser is provided with a condensation surface facing the evaporator, and a free travel space for molecules is formed between the evaporation surface and the condensation surface.

The evaporation surface is successively provided with creeping diffusion layer, radiation diffusion layer and wetting escape layer successively from top to bottom. The surfaces of the creeping diffusion layer and the radiation diffusion layer are continuous isosceles trapezoidal surfaces, and the surface of the wetting escape layer is rectangular. Among them, the width of the top side of the creeping diffusion layer is the smallest, and the width of the bottom side of the radiation diffusion layer is the same as that of the wetting escape layer.

The surface roughness of creep diffusion layer, radiation diffusion layer, and wetting escape layer decreases in turn. Wherein, the surface roughness of the creeping diffusion layer and the radiation diffusion layer gradually decreases from top to bottom, and the roughness of the lowest point on the surface of the creeping diffusion layer is greater than the roughness of the highest point of the radiation diffusion layer. The roughness of the entire surface of the moisture escape layer is the same, and the roughness of the lowest point of the radiation diffusion layer is the same as that of the moisture escape layer. Wherein, let the average roughness of the surface of the creeping diffusion layer be R _a , set the average roughness of the surface of the radiation diffusion layer as R _c , let the surface area of the creeping diffusion layer be S _a , let the surface area of the radiation diffusion layer be S _c , then

The molecular distillation cylinder has a built-in heavy component collection mechanism located under the evaporator, and the vertical distribution range of the heavy component collection mechanism is located in the inner peripheral area of the condensation surface of the condenser.

As a preferred technical solution of the rectification equipment of the present invention: a cooling pipe for dynamically circulating cooling liquid is arranged in the condenser.

As a preferred technical solution of the rectification equipment of the present invention: in the vertical direction, the distribution range of the condensation surface of the condenser matches the distribution range of the evaporation surface of the evaporator.

As a preferred technical solution of the rectification equipment of the present invention: the bottom of the molecular distillation cylinder is provided with a heavy component pipeline and a light component pipeline, the heavy component pipeline is equipped with a first flowmeter, and the light component pipeline is equipped with a second flowmeter. Wherein, the heavy component pipeline is connected with the heavy component collection mechanism, and the light component pipeline is connected with the cavity at the bottom of the molecular distillation cylinder.

As a preferred technical solution of the rectification equipment of the present invention: the molecular distillation cylinder is equipped with a vacuum sensor for sensing and monitoring the vacuum degree of the inner chamber of the molecular distillation cylinder.

As a preferred technical solution of the rectification equipment of the present invention: the creeping diffusion layer is divided into m continuous horizontal unit height areas, and the roughness of the m continuous horizontal unit height areas is R a1 , R _a1 from top to bottom. _a2 , R _a3 ,..., R _am , then Assuming that the radiation diffusion layer is divided into n continuous horizontal unit height areas, the roughness of the n continuous horizontal unit height areas is R _c1 +R _c2 +R _c3 +...+R _cn from top to bottom, then

The invention provides a control method of NMP dynamic rectification equipment, including the following links:

Link 1, "affinity" peristaltic diffusion of waste liquid: NMP waste liquid is diverted downward to the peristaltic diffusion layer on the evaporation surface through the distributor, and flows from top to bottom on the surface of the peristaltic diffusion layer. state.

Link two, rapid radiation diffusion of waste liquid: NMP waste liquid peristaltically falls through the "affinity" state of the peristaltic diffusion layer and gradually shunts. After the NMP waste liquid enters the radiation diffusion layer with reduced roughness, the NMP waste liquid flows along the surface of the radiation diffusion layer The diversion rate of the single original liquid flow is accelerated.

Link 3, liquid film evaporation of waste liquid: After the NMP waste liquid passes through the radiation diffusion layer and linearly accelerates the diversion and diffusion, the fluid cross-section of each diversion of the NMP waste liquid reaches the minimum at the bottom of the radiation diffusion layer, and the NMP waste liquid enters the wet area with the lowest surface roughness. Escape layer, NMP waste liquid forms a liquid film on the wet escape layer, and the liquid film evaporates in the vacuum environment of the molecular distillation cylinder. Among them, the light components with a large molecular free path reach the condensation surface of the condenser, and fall into the molecules after condensation. At the bottom of the distillation cylinder, NMP heavy components with small molecular free paths cannot reach the condensation surface of the condenser and fall into the heavy component collection mechanism.

Compared with prior art, the beneficial effect of the present invention is:

In the present invention, the surface of the evaporator in the molecular distillation cylinder is provided with a creeping diffusion layer with a relatively large roughness, a radiation diffusion layer with a second roughness, and a relatively smooth moisture escape layer, and the roughness of the creeping diffusion layer and the radiation diffusion layer are both It is set to a state of linear decrease from top to bottom, which not only forms a strong solid-liquid surface energy when the waste liquid contacts the evaporation surface, but also "creeps" down after being subjected to the liquid's own gravity, and spreads continuously (the roughness decreases, and the solid-liquid surface The energy can be reduced, and the diffusion ability is enhanced under the same gravity), forming a top-down multiple linearized "scattered" liquid state, and efficiently completing molecular distillation in the wet escape layer, thereby reducing the boiling phenomenon of waste liquid on the evaporation surface of the evaporator, Improve the effect of falling film molecular distillation.

Description of drawings

Fig. 1 is a structural schematic diagram of a molecular distillation cylinder in the present invention.

Fig. 2 is a schematic structural diagram of the evaporator in the present invention.

Fig. 3 is a schematic diagram of the creeping diffusion layer, the radiation diffusion layer and the moisture escape layer of the evaporator in the present invention.

FIG. 4 is a schematic diagram of a horizontal unit height area in the present invention.

Among them: 1-molecular distillation cylinder; 2-evaporator, 2a-evaporating surface, 201-creeping diffusion layer, 201a-horizontal unit height area, 202-radiation diffusion layer, 203-wetting escape layer; 3-condenser, 3a -condensation surface; 4-cooling pipe; 5-vacuum pipe; 6-feed pipe; 7-distributor; 8-heavy component collection mechanism; 9-heavy component pipeline; meter; 12-second flow meter; 13-vacuum sensor.

Detailed ways

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention, not to limit the present invention.

Embodiment one, the present invention relates to a kind of NMP dynamic rectification equipment, its main structure is as follows:

Please refer to FIG. 1 , the vacuum pipeline 5 is connected to the molecular distillation cylinder 1 , and the molecular distillation cylinder 1 is equipped with a vacuum sensor 13 , and the vacuum sensor 13 is used for sensing and monitoring the vacuum degree of the inner cavity of the molecular distillation cylinder 1 . The molecular distillation cylinder 1 has a built-in evaporator 2, and the evaporator 2 has an evaporation surface 2a. The molecular distillation cylinder 1 is equipped with a distributor 7 located above the evaporator 2. The upper side of the distributor 7 is connected to the feed pipe 6. The molecular distillation cylinder 1 has a built-in condenser 3. The condenser 3 is equipped with a cooling pipe 4. The cooling pipe 4 is dynamic Circulating cooling liquid, the condenser 3 is provided with a condensation surface 3a, the condensation surface 3a faces the evaporator 2, and in the vertical direction, the distribution range of the condensation surface 3a of the condenser 3 matches the distribution range of the evaporation surface 2a of the evaporator 2, Between the evaporating surface 2a and the condensing surface 3a, a molecule free travel space is formed. The molecular distillation cylinder 1 is provided with a heavy component collection mechanism 8, which is located below the evaporator 2, and the vertical distribution range of the heavy component collection mechanism 8 is located in the inner peripheral area of the condensation surface 3a of the condenser 3. The bottom of the molecular distillation cylinder 1 is provided with a heavy component pipeline 9 and a light component pipeline 10 , the heavy component pipeline 9 is equipped with a first flowmeter 11 , and the light component pipeline 10 is equipped with a second flowmeter 12 . The heavy component pipeline 9 communicates with the heavy component collection mechanism 8, the light component pipeline 10 communicates with the bottom cavity of the molecular distillation cylinder 1, and the sum of the liquid flow monitored by the first flowmeter 11 and the liquid flow monitored by the second flowmeter 12 , as a reference basis for the amount of NMP liquid supplied dynamically downward by the distributor 7 (combined with Fig. 2 and Fig. 3 ), so as to control the amount of liquid on the surface of the evaporator 2 more accurately, so that the creeping diffusion layer 201 and the radiation diffusion layer 202 1. The state of liquid flow generated in real time by wetting the escape layer 203 is optimal.

Referring to FIG. 2 and FIG. 3 , the evaporation surface 2 a is provided with a creeping diffusion layer 201 , a radiation diffusion layer 202 , and a wetting escape layer 203 successively from top to bottom. The surfaces of the creeping diffusion layer 201 and the radiation diffusion layer 202 are continuous isosceles trapezoidal surfaces, and the surface of the moisture escape layer 203 is rectangular. The width of the top side of the creeping diffusion layer 201 is the smallest, the width of the bottom side of the radiation diffusion layer 202 and the width of the rectangle of the moisture escape layer 203 are the same.

Please refer to Fig. 3 and Fig. 4, the surface roughness of the creeping diffusion layer 201, the radiation diffusing layer 202, and the moisture escape layer 203 decrease successively, that is, the surface of the creeping diffusing layer 201 is the roughest, followed by the radiation diffusing layer 202, and the moisture escape layer Layer 203 has the smoothest surface. The surface roughness of the creeping diffusion layer 201 and the radiation diffusion layer 202 gradually decreases from top to bottom, and the roughness at the lowest point of the creeping diffusion layer 201 is greater than the roughness at the highest point of the radiation diffusion layer 202 . In addition, the roughness of the entire surface of the moisture escape layer 203 is the same, and the roughness of the lowest point of the radiation diffusion layer 202 is the same as that of the moisture escape layer 203 . Let the average roughness of the surface of the creeping diffusion layer 201 be R _a , let the average roughness of the surface of the radiation diffusion layer 202 be R _c , let the surface area of the creeping diffusion layer 201 be S _a , let the surface area of the radiation diffusion layer 202 be S _c , but

The average roughness of the creeping diffusion layer 201 and the radiation diffusion layer 202 is the average roughness of all horizontal unit height areas 201a from top to bottom: suppose the creeping diffusion layer is divided into m continuous horizontal unit height areas 201a, such as In Fig. 4, the unit height of the horizontal unit height area 201a is △D. In Fig. 4, the creeping diffusion layer 201 is taken as an example to illustrate, and the same is true for the radiation diffusion layer 202. The roughness of m continuous horizontal unit height areas 201a Degrees from top to bottom are R _a1 , R _a2 , R _a3 ,..., R _am , then Assuming that the radiation diffusion layer 202 is divided into n continuous horizontal unit height areas, the roughness of the n continuous horizontal unit height areas 201a is R _c1 +R _c2 +R _c3 +...+R _cn from top to bottom, but

Embodiment 2. In the present invention, the liquid flow flows from top to bottom, and the creeping diffusion layer 201 on the upper side of the evaporation surface has a large roughness, that is, the creeping diffusion layer 201: the greater the interface energy of the evaporation surface 2a, the generated The solid-liquid surface energy is relatively large, and for the liquid that is continuously (falling) on the upper part, the external force (that is, gravity) required to roll down is large, and it can only "creep" and spread naturally downward along the evaporation surface.

The same is true for the radiation diffusion layer 202. The roughness is smaller than that of the peristaltic diffusion layer 201. However, in order to reduce fine boiling, the roughness should not be too low, and the liquid flow needs to be further divided, and the liquid flow forms a rapid "radiation split" diffusion.

The lower the evaporation surface 2a is, the smoother the surface is, the liquid flow reaches the wetting escape layer 203, and the wetting escape layer 203 is relatively smooth, the surface interface energy of the wetting escape layer 203 is small, and the solid-liquid surface energy generated is small, and the bottom of the radiation diffusion layer 202 The relatively dense "fine" liquid flow has been formed. Once these dense "fine" liquid flows enter the wetting escape layer 203, the solid-liquid surface energy decreases sharply, and a thinner liquid film is formed, which tends to be "completely wet". liquid film layer.

Embodiment 3. The present invention relates to a control method of NMP dynamic rectification equipment, including peristaltic diffusion, radiation diffusion, liquid film formation and other links:

Firstly, the waste liquid undergoes "affinity" creeping diffusion in the creeping diffusion layer 201: the NMP waste liquid passes through the distributor 7 and shunts down to the creeping diffusion layer 201 on the evaporation surface, flows from top to bottom on the surface of the creeping diffusion layer 201, and the NMP waste The liquid forms a creeping state on the surface of the creeping diffusion layer 201, and the NMP waste liquid rolls down evenly along the surface of the creeping diffusion layer 201, and in the process of rolling down, the surface roughness of the creeping diffusion layer 201 decreases continuously, and the wriggling NMP waste liquid It also continues to generate "diversion" outwards.

Then, the waste liquid rapidly radiates and diffuses in the radiation diffusion layer 202: the NMP waste liquid wriggles and falls in the "affinity" state of the peristaltic diffusion layer 201 and gradually shunts. After the NMP waste liquid enters the radiation diffusion layer 202 with reduced roughness, the NMP waste liquid The splitting rate of the single original liquid flow along the surface of the radiation diffusion layer 202 is accelerated, wherein, the splitting rate of the single original liquid flow: the flowing liquid of a unit cross-sectional area diffuses to both sides within a unit longitudinal distance The number of tributaries. For example, a flowing liquid with a cross-section of ^1mm2 forms 3 branches within a flow distance of 100mm (including the original liquid flow, which is actually 2 more new liquid flows), and the split flow rate is 3. For example, a flowing liquid with a cross-section of 1.5mm ² forms three branches within a flow distance of 100mm, and the flow rate is 2. For example, a flowing liquid with a cross-section of ^2mm2 forms 5 branches within a flow distance of 100mm, and the split flow rate is 2.5.

Finally, the waste liquid forms a liquid film in the wetting escape layer 203 and evaporates: after the NMP waste liquid passes through the radiation diffusion layer 202 and accelerates the split flow, the fluid cross section of each split flow of the NMP waste liquid reaches the minimum at the bottom of the radiation diffusion layer 202, and the NMP waste liquid Entering the wetting escape layer 203 with the lowest surface roughness, the NMP waste liquid forms a liquid film on the wetting escape layer 203, and the liquid film evaporates in the vacuum environment of the molecular distillation cylinder 1, wherein the light components with a large molecular free path reach the condensed The condensing surface 3a of the condenser 3 falls into the bottom of the molecular distillation cylinder 1 after condensation, and the NMP heavy component with a smaller molecular free path cannot reach the condensing surface 3a of the condenser 3 and falls into the heavy component collecting mechanism 8 .

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention should be included in the protection of the present invention. within range.

Claims (7)

1. A dynamic rectification device for NMP, comprising a molecular distillation cylinder (1), the molecular distillation cylinder (1) is connected with a vacuum pipeline (5), and the molecular distillation cylinder (1) is built-in with an evaporator with an evaporation surface (2a) device (2), the molecular distillation cylinder (1) is equipped with a distributor (7) located above the evaporator (2), and a feed pipe (6) communicated with the distributor (7), and the molecular distillation cylinder (1) is equipped with Condenser (3), condenser (3) is provided with the condensing surface (3a) facing evaporator (2), forms molecular free travel space between evaporating surface (2a) and condensing surface (3a), is characterized in that: The evaporation surface (2a) is successively provided with a creeping diffusion layer (201), a radiation diffusion layer (202), and a wetting escape layer (203) successively from top to bottom; The surfaces of the creeping diffusion layer (201) and the radiation diffusion layer (202) are continuous isosceles trapezoidal surfaces, and the surface of the wetting escape layer (203) is rectangular; Wherein, the width of the top side of the creeping diffusion layer (201) is the smallest, and the width of the bottom side of the radiation diffusion layer (202) is the same as that of the moisture escape layer (203); The surface roughness of the creeping diffusion layer (201), the radiation diffusion layer (202), and the wetting escape layer (203) decreases sequentially; Wherein, the surface roughness of the creeping diffusion layer (201) and the radiation diffusion layer (202) gradually decreases from top to bottom, and the roughness of the lowest point of the creeping diffusion layer (201) is greater than that of the radiation diffusion layer (202). Roughness at the highest point position; Wherein, the roughness of the entire surface of the moisture escape layer (203) is the same, and the roughness of the lowest point of the radiation diffusion layer (202) is the same as that of the moisture escape layer (203); Wherein, the average roughness of the surface of the creeping diffusion layer (201) is set as R _a , the average roughness of the surface of the radiation diffusion layer (202) is set as R _c , the surface area of the creeping diffusion layer (201) is set as S _a , and the radiation diffusion layer (202) is set as S a The surface area of layer (202) is S _c , then The molecular distillation cylinder (1) has a built-in heavy component collection mechanism (8) located below the evaporator (2), and the vertical distribution range of the heavy component collection mechanism (8) is located on the condensation surface ( 3a) Inner area. 2. A kind of NMP dynamic rectification equipment according to claim 1, is characterized in that: A cooling pipe (4) for dynamically circulating cooling liquid is arranged in the condenser (3). 3. A kind of NMP dynamic rectification equipment according to claim 1, is characterized in that: In the vertical direction, the distribution range of the condensation surface (3a) of the condenser (3) matches the distribution range of the evaporation surface (2a) of the evaporator (2). 4. A kind of NMP dynamic rectification equipment according to claim 1, is characterized in that: The bottom of the molecular distillation cylinder (1) is provided with a heavy component pipeline (9) and a light component pipeline (10), and the heavy component pipeline (9) is equipped with a first flow meter (11), and the light component pipeline (10 ) is configured with a second flow meter (12); Wherein, the heavy component pipeline (9) communicates with the heavy component collection mechanism (8), and the light component pipeline (10) communicates with the cavity at the bottom of the molecular distillation cylinder (1). 5. A kind of NMP dynamic rectification equipment according to claim 1, is characterized in that: The molecular distillation cylinder (1) is equipped with a vacuum sensor (13) for sensing and monitoring the vacuum degree of the inner cavity of the molecular distillation cylinder (1). 6. A kind of NMP dynamic rectification equipment according to claim 1, is characterized in that: Assuming that the creeping diffusion layer is divided into m continuous horizontal unit height areas (201a), the roughness of the m continuous horizontal unit height areas (201a) is R _a1 , R _a2 , R _a3 , .. .、R _am , then Assuming that the radiation diffusion layer (202) is divided into n continuous horizontal unit height areas, the roughness of the n continuous horizontal unit height areas (201a) is R _c1 +R _c2 +R _c3 +... +R _cn , then 7. a control method of NMP dynamic rectification equipment, is characterized in that, adopts a kind of NMP dynamic rectification equipment described in any one of claim 1 to 6, comprises following link content: Link 1, waste liquid "affinity" peristaltic diffusion The NMP waste liquid is diverted downward to the creeping diffusion layer on the evaporation surface through the distributor, and flows from top to bottom on the surface of the creeping diffusion layer, and the NMP waste liquid forms a creeping state on the surface of the creeping diffusion layer; Link 2, Rapid Radiation Diffusion of Waste Liquid After the NMP waste liquid enters the radiation diffusion layer with reduced roughness, the NMP waste liquid peristaltically falls in the "affinity" state of the peristaltic diffusion layer and gradually shunts, and the NMP waste liquid flows along the surface of the radiation diffusion layer. accelerate; Link 3, waste liquid film evaporation After the NMP waste liquid passes through the radiation diffusion layer and linearly accelerates the split diffusion, the fluid cross-section of each split of the NMP waste liquid reaches the minimum at the bottom of the radiation diffusion layer, and the NMP waste liquid enters the wet escape layer with the lowest surface roughness, and the NMP waste liquid escapes in the wet A liquid film is formed on the layer, and the liquid film evaporates in the vacuum environment of the molecular distillation cylinder. Among them, the light component with a large molecular free path reaches the condensation surface of the condenser, and falls to the bottom of the molecular distillation cylinder after condensation, and the molecular free path is small. The NMP heavy components cannot reach the condensation surface of the condenser and fall into the heavy component collection mechanism.