CN110431371A

CN110431371A - A kind of tube mixer

Info

Publication number: CN110431371A
Application number: CN201780088617.5A
Authority: CN
Inventors: 王昌松; 刘耀倩; 陈晶晶; 陆小华; 吴佳军; 宋健
Original assignee: Nanjing Tech University
Current assignee: Nanjing Tech University
Priority date: 2017-06-07
Filing date: 2017-06-07
Publication date: 2019-11-08
Also published as: EP3587987A1; EP3587987A4; WO2018223296A1; EP3587987B1

Abstract

A kind of tube mixer, it has included the inner sleeve (2) of immixture and the outer tube (1) for playing heat exchange, inner sleeve (2) is located in outer tube (1), and the section of inner sleeve (2) is hexagon and is composed by one section along the inner tube of tube hub clockwise twist and the inner tube of counterclockwise twists.The tube mixer is that one kind can be for high solids content, high viscosity or fibrous complex fluid, while realizing the tube mixer for strengthening mass transfer and heat transfer, and has good antiscale property, anti-clogging and replace churned mechanically effect.

Description

Tubular mixer

Technical Field

The invention belongs to fluid mixing equipment, and particularly relates to a tubular mixer with a heat exchange function.

Background

Mixing is a unit operation in which two or more materials are dispersed within each other to a certain degree of homogeneity, by mechanical or hydrodynamic means. With the gradual deepening of scientific research, the mixing effect is more and more emphasized in the aspects of chemical industry, petroleum, power, light industry and the like, and the purpose of mixing is achieved by mechanical stirring, gas circulation stirring and hydraulic stirring in many fields. In addition, many projects or project-related processes require heating or temperature control of the raw materials, the discharge and the reaction process; the temperature not only affects the energy consumption of the system, but also is a key factor for ensuring the normal and efficient operation of the reaction process. Therefore, the heat exchange technology is combined with the mixing technology, and the research and development of the high-efficiency and energy-saving mixer has important significance for reducing the production cost and saving energy.

At present, the mixing equipment commonly used in industry comprises a stirring mixing kettle, a static mixer, a circulating mixer and the like, and the commonly used heat exchange equipment comprises a tubular heat exchanger, a plate heat exchanger, a finned heat exchanger and the like, but the equipment cannot simultaneously enhance mixing and heat exchange, so that the selection of process schemes and conditions is limited, and the equipment becomes a main bottleneck of enhancing transfer in a fluid process. On the other hand, many process raw materials have high solid content, high apparent viscosity and complex rheological property, such as fermentation raw materials (straw and poultry manure systems and the like), which all cause the blockage and scaling of equipment, so that the process transfer efficiency is greatly reduced, and the continuous and stable operation of the system is influenced. With the improvement of mixing technology and heat exchange technology, mixers are inserted into a plurality of heat exchangers, such as a horizontal liquid-solid fluidized bed heat exchanger with a Kenics static mixer inserted in a pipe, the configuration can effectively improve the distribution condition of particles, but the heat exchanger with the structure is only suitable for a system with low solid content of 2 wt% to 4 wt%, and the high solid content system has great flow resistance during heat exchange due to the existence of pipe internals, so that the power consumption of the process is increased. In recent years, tubular mixers have been developed rapidly, such as multi-stage vortex tube mixers, S-K type mixers, tube bundle tubular static mixers, which are mainly used for filtering flocs in water, and such tubular mixers are only suitable for low-solid-content, low-viscosity simple fluids such as sewage. Chinese patent CN201510185307.8 discloses a tubular mixer with spiral channel, which has a spiral groove on the outer wall of the inner tube, and the spiral groove is connected with the inner wall of the outer tube to form the spiral channel, and the mixer with this structure can provide a long mixing length in a short axial distance, and provide a better mixing effect in the same mixing time. However, the channel is a spiral channel, the configuration is only suitable for a system with low solid content, and for a system with high solid content, especially straws containing fibers, the channel is easy to block, so that the mixing effect can be reduced.

On the other hand, chinese patent CN201510305639.5 discloses a double pipe heat exchanger suitable for high solid content sewage, which is suitable for high solid content sewage, wherein the dirt and impurities in the sewage are not easy to form scale or block on the four walls of the sewage channel, thus ensuring the heat exchange efficiency and continuous and stable operation of the heat exchanger, and the tube pass and shell pass of the heat exchanger have high convective heat transfer efficiency, so that the heat exchanger has high enhanced heat exchange performance, but the cross section of the twisted pipe in the heat exchanger is triangular, and the configuration has dead angles for high solid content and high viscosity complex fluid containing fibers, and the enhanced mixing effect cannot be achieved. In addition, although the twisted tube heat exchanger with the oval cross section has certain advantages in enhancing heat exchange performance, the twisted tube heat exchanger is only limited to single-phase fluid without solid particles, such as sulfuric acid temperature reduction, ammonia preheating, lubricating oil temperature reduction and the like.

In conclusion, aiming at complex fluid with high solid content, high viscosity or fiber, the development of novel fluid mixing equipment with the functions of mass transfer enhancement and heat transfer enhancement is of great significance, the energy consumption of mixing and heat exchange of the system can be reduced, and the reaction efficiency is improved.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provide a tubular mixer which simultaneously realizes the mass transfer and heat transfer enhancement aiming at complex fluid with high solid content, high viscosity or fiber and has the functions of preventing scaling and blocking and replacing mechanical stirring. The invention has important application background in the fields of petrochemical industry, food processing, biological fermentation and the like.

The method is realized by the following technical scheme:

the utility model provides a tubular mixer, its outer tube that includes interior sleeve pipe that plays the mixing action and play the heat transfer effect, interior sleeve pipe is located the outer tube, interior sleeve pipe's cross-section for the hexagon and by the inner tube that twists clockwise along the pipe center and the inner tube combination of anticlockwise distortion form.

The tubular mixer is suitable for material systems with high solid content and high viscosity, and has the advantages of simple structure, blockage and scaling prevention, and integration of heat exchange and mixing.

Preferably, the cross section of the inner sleeve is an equilateral hexagon. The central axis of the inner sleeve is a straight line or a curve, and a straight central axis is adopted under the preferred condition.

This interior sleeve pipe is formed by the inner tube of the clockwise uniform distortion of pipe center and the combination of the inner tube of the anticlockwise uniform distortion, and preferred, interior sleeve pipe moment of torsion, the pipe length that 360 corresponds of pipe wall spiral deformation around the pipe central axis is 300 and one-tenth 800mm, preferred 500 and one-tenth 800 mm. Experiments show that the medium channel space is too small due to the fact that the medium channel space is too large, the mixer cannot work normally and is easy to scale, and the mixing effect and the heat exchange effect can be reduced due to too small torque. In addition, the torque of the two sections of the inner pipe formed by clockwise twisting and anticlockwise twisting can be the same or different, and the influence on the mixing and heat exchange effects is not obvious.

Preferably, the diameter of the inscribed circle of the hexagonal section of the inner sleeve is 20-150mm, preferably 80-150mm, and experiments show that the heat exchange efficiency and the mixing effect are affected by too large or too small diameter of the inscribed circle, and dirt or blockage on the wall surface of the inner sleeve is easily caused.

The cross section of the outer sleeve is not limited, and can be round, square, hexagonal and the like, and for convenience of production and better heat exchange efficiency, the interface of the outer sleeve is preferably round. The distance between the diameter of the inscribed circle of the inner sleeve and the diameter of the inscribed circle of the outer sleeve is 5-15mm, preferably 10-15mm, and the experiment shows that: too large or too small spacing can reduce heat exchange effect, and too large spacing can also cause higher energy consumption and cost.

Furthermore, the diameter of the inscribed circle of the inner sleeve and the outer sleeve can be adjusted within the range of the invention according to actual requirements, and in order to realize better anti-scaling and anti-clogging effects, higher mixing effect and better heat exchange performance, the diameter D of the inscribed circle is preferably selected when the total solid content TS is 4-10 percent₁20-80 mm diameter D of the inner sleeve and the inscribed circle₂The outer sleeve with the diameter of 30-95 mm is preferred, and the diameter D of an inscribed circle is selected for materials with the total solid content TS of 10-15%₁Diameter D of the inner sleeve and the inscribed circle of 80-150mm₂The outer sleeve is preferably 95-165 mm.

Further, the inner casing according to the present invention may comprise one or more of a combination of an inner tube twisted clockwise along the center of the tube and an inner tube twisted counterclockwise as a constituent unit; the inner tube according to the present invention, wherein the inner tube (L) is uniformly twisted clockwise along the center of the tube₁) With the inner tube (L) twisted uniformly counterclockwise₂) May preferably be L₁:L₂(0.5-2): 1, the length ratio in this range has no significant effect on the mixing effect, and below or above this range, the mixing effect is significantly reduced.

In one technical scheme, the tubular mixer comprises a material mixing channel and a heat exchange medium channel, wherein the material mixing channel is formed by an inner sleeve, and a material feeding hole and a material discharging hole are respectively formed in two ends of the material mixing channel; the heat exchange medium channel is composed of an annular gap between the outer sleeve and the inner sleeve, two ends of the heat exchange medium channel formed by the gap between the outer sleeve and the inner sleeve can be sealed, and the heat exchange medium channel or the heat exchange medium main channel is provided with a heat exchange medium inlet pipe and a heat exchange medium outlet pipe. In order to obtain better heat exchange effect, the material feeding hole is preferably corresponding to the outlet pipe of the heat exchange medium, and the material discharging hole is corresponding to the inlet pipe of the heat exchange medium.

The invention has the beneficial effects that:

1. it is suitable for material system with high solid content TS of 4-15 wt% and containing solid or fiber, and has no dead angle, less fouling and less jamming.

2. Compared with a triangular twisted tube mixer, the mixer has smaller dead space ratio, and can remarkably enhance the mixing effect.

3. The heat exchange efficiency of the tube pass and the shell pass is high, so that the heat exchange performance is high, and the power consumption of the process pump is low.

4. The mixing channel is formed by splicing a coaxial circular tube and a twisted tube which are nested with each other, can be conveniently manufactured by using a conventional machining technology, and is low in cost.

5. The materials can be fully mixed and heat exchanged in the mixing channel, the reaction efficiency of the later system is improved, and the energy consumption is reduced.

Drawings

FIG. 1 is an overall view of a mixer with heat exchange function;

FIG. 2 is a hexagonal twist tube with internal channels;

FIG. 3 schematic cross-sectional view of a mixer

In the figure, 1-outer sleeve, 2-inner sleeve, 3-A inlet pipe, 4-B inlet pipe, 5-outlet pipe, 6-heat exchange medium inlet pipe, 7-heat exchange medium outlet pipe and 8-hexagonal inscribed circle O₁Cross-section, 9-hexagonal cross-section, 10-jacket round tube O₂Cross section.

Detailed description of the invention

The invention is further described below with reference to the figures and examples. The following description is not to be construed as limiting the scope of the invention.

The invention relates to a tubular mixer which aims at complex fluid with high solid content, high viscosity or fiber and simultaneously realizes the enhancement of mass transfer and heat transfer. The tubular mixer is suitable for material systems with high solid content and high viscosity, and has the advantages of simple structure, blockage and scaling prevention, and integration of heat exchange and mixing.

As shown in fig. 2, the inner casing of the present invention may be a hexagonal twisted pipe having a hexagonal cross section and formed by combining a section of an inner pipe uniformly twisted clockwise along the center of the pipe and a section of an inner pipe uniformly twisted counterclockwise. The cross-section of the hexagonal twisted tube is a regular hexagon, the central axis of which is a straight line or a curve, and a straight central axis as shown in fig. 2 is adopted under a preferable condition.

One of the important parameters of the hexagonal twisted tube is torque, namely the length of the tube corresponding to the tube wall twisted and deformed by 360 degrees around the central axis of the tube, and the torque of the hexagonal twisted tube is 300-800 mm. The diameter of the inscribed circle of the hexagonal section of the hexagonal twisted tube is 20-150mm, as shown in figure 3. The inner tube (L) of the inner sleeve is uniformly twisted clockwise along the center of the tube₁) With the inner tube (L) twisted uniformly counterclockwise₂) Has a length ratio of L₁:L₂(0.5-2): 1. the material and the heat exchange medium directly exchange heat through the pipe wall of the hexagonal twisted pipe.

The outer sleeve in this example can be a common circular sleeve, the cross section of the outer sleeve is circular, the pipe diameter of the outer sleeve is larger than that of the inner sleeve, and the distance between the wall of the outer sleeve and the inner sleeve is 5-15 mm. The cross-sectional structure of the inner and outer sleeves in this example is shown in fig. 3.

Fig. 1 shows a relatively perfect tubular mixer, which comprises an outer sleeve 1, an inner sleeve 2, a material a inlet 3, a material B inlet 4, a material outlet 5, a heat exchange medium inlet 6, and a heat exchange medium outlet 7, wherein the outer sleeve is a heat exchange medium channel, the inner sleeve is a material mixing channel, the inner sleeve is located in the outer sleeve, the cross section of the inner sleeve is hexagonal, and the inner sleeve is formed by combining a section of inner tube which is uniformly twisted clockwise along the center of the tube and an inner tube which is uniformly twisted counterclockwise, as shown in fig. 2-3, the two ends of the inner sleeve are respectively connected with a feeding tube opening a, a feeding tube opening B and a material outlet 5. The heat exchange medium flows into the annular gap between the circular-section sleeve and the hexagonal-section twisted tube from the heat exchange medium inlet 6 and flows out from the heat exchange medium outlet 7, and the outer sleeve is provided with a heat insulation material.

Performance testing

The structure shown in fig. 1 is adopted below, the outer sleeve is a circular sleeve, the material a is straw, the material B is a cmc (carboxy methyl cellulose) solution (mass fraction is 1%), and the heat exchange medium is water. The material inlet temperature is 10 ℃, and the heat exchange medium inlet temperature is 55 ℃. The mixing effect is characterized by adopting a tracer method, 0.7mol/L KCl solution is injected into an inlet, the voltage of the KCl solution is measured by a conductivity meter (DDSJ-308A) at an outlet, and the dimensionless variance of the step-by-step residence time is calculated through the voltage

And a beckia number (Pe),

the closer to 1, the better the mixing effect, the closer to 0 Pe, the larger the axial back mixing, and the flow state close to the complete mixing flow. The material inlet speeds of the examples and comparative examples in Table 1 were the same, the heat exchange medium inlet speed was also the same, D₁Is the diameter of a hexagon inscribed circle, D₂Is the outer tube diameter, n₁And n₂Respectively, the torque of the two twisted tubes, L₁And L₂Respectively, are lengths of two twisted tubes (see fig. 2).

The operating conditions and the results of the mixed heat transfer characterization for examples 1-7 and comparative examples 1-8 are shown in table 1.

TABLE 1 operating conditions and characterization results for the examples

As can be seen from the above table, the mixer of comparative example 1 has better heat exchange performance, but the co-twisted hexagonal structure does not disturb the fluid as the mixer of example 1; comparative example 3 a triangular twisted tube mixer has a better heat exchange effect, but the mixing effect is inferior to that of a hexagonal twisted tube. The hexagonal straight tube and the elliptical twisted tube are blocked and cannot be measured. Through the analysis, the twisted tube mixer with the hexagonal cross section has better effect.

In comparison with examples 1 to 3, the mixers in examples 2 to 3 are inferior to the mixer in example 1 in mixing and heat exchange effects because the hexagonal twisted tubes in the material passage have too large torque, so that the medium passage space is too small, and the mixer cannot work normally, so that the twisted tubes with the torque exceeding 800mm are easy to scale, and the mixing and heat exchange effects are reduced by too small torque. Therefore, the torque of the torque tube is in the range of 300-.

For a material system with higher solid content, the blockage, scaling and enhanced mixing and heat exchange can be prevented by changing the torque and the length of the two sections of twisted tubes or the diameter of the hexagonal inscribed circle and the diameter of the outer tube. The torque and the length of the two sections of twisted tubes are respectively changed in the embodiment 4 and the embodiment 5, the structural sizes of the inner tube and the outer tube are changed in the embodiment 7, and according to the representation result, the mixing and heat exchange effects are similar to those of the embodiment 1, so that various combinations can be flexibly selected according to specific conditions in actual operation.

As can be seen from example 6 and comparative example 5, for the material containing fiber with high solid content and high viscosity, the diameter of the hexagonal inscribed circle is too small to easily cause blockage; from the embodiment 1 and the comparative examples 6 to 7, it can be known that, under the same inner pipe condition, the annular gap between the inner pipe and the outer pipe is reduced or enlarged, the mixing effect is not greatly influenced, but the temperature difference is insufficient due to too small annular gap, and the material in the inner pipe is not heated enough, so that the heat exchange effect is reduced; as can be seen from the example 7 and the comparative example 8, the diameter of the hexagonal inscribed circle is too large, slight scaling can be caused, the rotational flow pattern is damaged, and the heat exchange resistance is increased, so that the mixing effect and the heat exchange performance are reduced. In summary, D is selected for the material with 4-10% of TS₁20-80 mm of inner tube and D₂The outer tube of 30-95 mm is preferred, and D is selected for materials with TS of 10-15%₁＝80～150mm、D₂The outer tube is preferably 95-165 mm. In the aboveThe high-scale and anti-clogging effect and the high mixing effect and the high heat exchange performance can be realized under the TS-pipe diameter condition, and the effect can be seriously influenced when a large deviation exists.

The specific implementation method and implementation effect of the tubular mixer of the invention are described above by taking a tubular mixer with a relatively simple design as an example and combining a mixing performance characterization method generally accepted in the professional field. However, the protection scope of the present invention is not limited thereto, and actually, the tubular mixer with heat exchange function provided by the present invention can be changed into various specific structural forms according to the structural features thereof, for example, a plurality of inner sleeves are arranged in an outer sleeve, the torque and the pipe diameter are changed according to different material systems, and a plurality of inner pipes uniformly twisted clockwise and inner pipes uniformly twisted counterclockwise are arranged and combined; if a combination of a section of inner tube twisted clockwise along the center of the tube and a section of inner tube twisted counterclockwise is used as a constituent unit, the inner cannula according to the present invention may further comprise one or more constituent units; the tubular mixer constructed by various changes and combinations thereof does not depart from the protection scope of the invention.

Claims

The utility model provides a tubular mixer which characterized in that, is including the interior sleeve pipe that plays the mixing action and the outer tube that plays the heat transfer effect, interior sleeve pipe is located the outer tube, interior sleeve pipe's cross-section for the hexagon and by the inner tube that twists clockwise along the pipe center and the inner tube combination of anticlockwise distortion forms.
The tube mixer of claim 1 wherein the cross-section of the inner sleeve is an equilateral hexagon.
The tube mixer of claim 1 wherein the central axis of the inner sleeve is straight or curved and the inner sleeve is formed by a combination of an inner tube uniformly twisted clockwise and an inner tube uniformly twisted counter-clockwise along the center of the tube.
The tube mixer according to claim 1, wherein the internal casing torque, i.e. the length of the tube corresponding to a helical deformation of the tube wall of 360 ° around the central axis of the tube, is 300-.
The tube mixer according to claim 1, wherein the inner casing has a hexagonal cross-section with an inscribed circle diameter of 20 to 150mm, preferably 80 to 150 mm.
The tube mixer according to claim 1, wherein the distance between the diameter of the inscribed circle of the inner sleeve and the diameter of the inscribed circle of the outer sleeve is 5-15mm, preferably 10-15 mm.
The tube mixer according to claim 1, wherein the inner sleeve has a length ratio of the inner tube uniformly twisted clockwise to the inner tube uniformly twisted counterclockwise along the center of the tube of (0.5-2): 1.
the tube mixer according to claim 1, wherein the inner tube of the present invention comprises one or more constituent units, each of which is a combination of a clockwise twisted inner tube and a counterclockwise twisted inner tube along the center of the tube.
The tube mixer according to claim 1, comprising a material mixing channel and a heat exchange medium channel, wherein the material mixing channel is composed of an inner sleeve, and a material inlet and a material outlet are respectively arranged at two ends of the material mixing channel; the heat exchange medium channel is composed of an annular gap between the outer sleeve and the inner sleeve, and an inlet pipe and an outlet pipe of the heat exchange medium are arranged on the heat exchange medium channel or the heat exchange medium main channel.
The tube mixer of claim 9, wherein the material inlet port corresponds to an outlet tube for the heat exchange medium and the material outlet port corresponds to an inlet tube for the heat exchange medium.