Tubular reactor with multi-strand rotary jet flow impacting spiral flow

Abstract

The invention relates to a tubular reactor, in particular to a tubular reactor with multi-strand rotary jet flow impacting spiral flow, which comprises a core tube (1), a core tube fixing piece (2), a transverse flow inlet tube (3), a reaction tube (4), a jet flow tube (5), a twisting element (6), a mixing element (7) and a jacket (8). A plurality of jet pipes (5) are arranged to be flush with the inner wall of a core pipe (1) or extend inwards, and twisting elements (6) are inserted into the jet pipes (5). The jet fluid rotationally impacts the cross-flow fluid under the action of the twisting element (6), and the cross-flow fluid spirally flows in the reaction tube (4) under the action of the tangentially mounted cross-flow inlet tube (3). And the reaction effect of the reaction fluid is obviously improved under the combined action of the rotary jet flow and the spiral flow. The reactor has the advantages of being simple in structure, high in pressure bearing capacity, good in reaction and heat exchange effect, few in by-product and not prone to scaling, is suitable for gas-liquid and liquid-liquid reaction processes, and is particularly suitable for the rapid reaction process with the high heat exchange requirement.

Description

Technical Field

[0001] The invention relates to a tubular reactor, in particular to a tubular reactor utilizing a rotating jet to impact a spiral flow. Background Art

[0002] Spiral flow is a common flow form in process industries such as chemical and petrochemical industries. It is mainly used to enhance unit processes such as heat transfer, mixing, separation, and transportation of fluids. There are three main ways to generate spiral flow: one is to use a tangential inlet, such as a cyclone separator; the second is to insert a twisting element in the straight channel, such as a Kenics static mixer; the third is to use a spiral pipe, such as a spiral coil heat exchange element. The enhancement mechanism of spiral flow can be summarized as follows: During the spiral flow of the fluid, the fluid particles are acted upon by centrifugal force, which causes it to generate a lateral flow perpendicular to the mainstream direction, forming a secondary vortex. The mainstream fluid and the boundary fluid are exchanged and renewed, and the thickness of the flow and heat transfer boundary layer will also be reduced to a certain extent.

[0003] Jets are a common flow form in process industries and aerospace. When a high-speed fluid is ejected into another fluid, the high-speed fluid is called a jet fluid, and the other low-speed or stationary fluid is called an ambient fluid or a cross-flow fluid. The jet fluid will entrain the cross-flow fluid during high-speed flow, and the two fluids will mix with each other. As the flow path grows, the mixing area expands and the flow speed slows down. When the space where the cross-flow fluid is located is small, the momentum of the jet fluid is not consumed by the cross-flow fluid. At this time, the jet fluid will impact the wall of the cross-flow fluid space at a higher speed, significantly thinning the flow and heat transfer boundary layer, and improving the fluid convective heat transfer coefficient.

[0004] Based on the flow pattern of the jet itself, the jet can be divided into two types: direct current jet and rotary jet. A direct current jet refers to a fluid ejected along the axis of the jet tube or nozzle, while a rotary jet refers to a jet spirally flowing around the axis of the jet tube or nozzle. While there is an axial velocity, there is also a large tangential velocity. Previous research results show that when the jet flow rate and flow area are constant, the impact intensity of the rotary jet on the surface is weakened compared to the direct current jet, but the impact area is increased, and at the same time, the entrainment and mixing ability of the cross-flow fluid is significantly stronger than that of the direct current jet. Therefore, rotary jets have attracted the attention of more and more scholars in recent years.

[0005] In summary, both spiral flow and rotating jet can enhance the mixing and heat transfer process of fluids. If the above two flow modes are combined in the same reactor, the reaction effect of the reactor and the ability to control the reaction temperature will be significantly improved. It has a very broad application prospect for enhancing the exothermic reaction process in the chemical, petrochemical and other fields. Summary of the invention

[0006] The purpose of the present invention is to provide a tubular reactor with multiple rotating jets impacting spiral flows, in which the reaction fluid of the reactor flows in a spiral, and at the same time, the reaction fluid flows in a rotating jet, and the two fluids are mutually entrained and mixed, and at the same time, under the combined action of the rotating jet and the spiral flow, the heat transfer boundary layer of the reaction tube wall is significantly thinned, and the mixing effect and heat transfer capacity of the reactor are significantly enhanced, so as to realize an efficient reactor with good reaction effect, stable and controllable reaction.

[0007] The objective of the present invention is achieved through the following technical solutions: A tubular reactor with multiple rotating jets impacting spiral flows, the reactor comprising a core tube, a core tube fixing member, a cross-flow inlet tube, a reaction tube, a jet tube, a twisting element, a mixing element and a jacket; the core tube is fixed by welding with the core tube fixing member and inserted into the reaction tube concentrically; the core tube outlet in the reaction tube is sealed by welding with a blind plate, a plurality of through holes are arranged on the surface of the core tube, the jet tubes are welded and fixed in the through holes, and the jet tubes are flush with the inner surface of the core tube or extended inwardly; the twisting element is inserted into each jet tube, and the twisting element is directly The diameter should ensure that its contour fits the inner wall of the jet tube, and the length is equal to the jet tube; the twisting element adopts a spiral twisted band shaped swirl element, and its twist rate is determined according to the flow velocity and physical properties of the jet fluid; the cross-flow inlet tube is installed tangentially to the reaction tube, that is, the axis of the cross-flow inlet tube is perpendicular to the axis of the reaction tube, and the outermost side of the inner wall of the cross-flow inlet tube is tangent to the inner wall of the reaction tube; according to the different diameters of the reaction tube, one, two or more cross-flow inlet tubes are used, each of which has the same specifications and is evenly distributed circumferentially in the same cross-section of the reaction tube.

[0008] In the tubular reactor with multiple rotating jets impacting spiral flows, the mixing element added behind the core tube in the reaction tube is a commercial static mixing element.

[0009] The tubular reactor with multiple rotating jets impacting spiral flows, the static mixing elements used by the mixing elements include Kenics, SX, SL, or directly use empty tubes.

[0010] In the tubular reactor with multiple rotating jets impacting spiral flows, the length of the mixing element is determined according to the reaction residence time and the reaction effect.

[0011] The tubular reactor with multiple rotating jets impacting spiral flows is installed horizontally or vertically.

[0012] The advantages and effects of the present invention are: 1. Both fluids involved in the reaction are in a swirling state and are perpendicular to each other, with strong turbulence, good mixing effect and high reaction quality.

[0013] 2. The jet fluid is sprayed into the reaction tube by multiple jet tubes, which not only realizes jet enhancement but also achieves distributed mixing.

[0014] 3. The jet fluid forms multiple rotating jets under the action of the twisting element, which expands the jet entrainment range and further improves the mixing effect.

[0015] 4. The present invention is applicable to liquid-liquid and gas-liquid reaction processes, has good reaction effect, few by-products, and high production efficiency, and is particularly applicable to highly exothermic reaction processes with high heat exchange requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic structural diagram of the tubular reactor of the present invention; Figure 2 It is the structural diagram of jet tubes arranged in a rectangular pattern (in sequence); Figure 3 This is the structural diagram of the triangular arrangement (cross arrangement) of jet tubes; Figure 4 This is the assembly relationship diagram of the twisting element and the jet tube; Figure 5 It is a structural diagram of a straight-line twisting element; Figure 6 It is a structural diagram of a three-pointed star-shaped twisting element; Figure 7 It is the structural diagram of the cross-shaped torsion element; Figure 8 This is the assembly diagram of the circular cross-flow inlet pipe; Fig. 9 This is the assembly diagram of the rectangular cross-flow inlet pipe. DETAILED DESCRIPTION

[0017] The present invention is described in detail below with reference to the accompanying drawings A tubular reactor with multiple rotating jets impacting spiral flows is composed of a core tube, a core tube fixing part, a cross-flow inlet tube, a reaction tube, a jet tube, a twisting element, a mixing element and a jacket.

[0018] The core tube is placed at the center axis of the reactor, and its function is to arrange the jet tube so that the jet fluid is ejected radially outward along the core tube into the reaction tube, impacting the spirally flowing cross-flow fluid, and generating entrainment and mixing enhancement effects. The core tube adopts a smooth straight tube, the diameter of which is 20% to 60% of the diameter of the reaction tube, and the length of the core tube is 30% to 80% of the length of the reaction tube. The surface of the core tube is evenly distributed with multiple through holes along the circumferential and axial directions, and the jet tube is welded and fixed in the through hole. The core tube outlet in the reaction tube is sealed by blind plate welding to ensure that all the jet fluid is ejected through the jet tube. The inlet of the core tube can be connected to an external pipeline or equipment by welding or flange connection.

[0019] The jet tube axis is perpendicular to the inner surface of the core tube, and the jet tubes can be arranged in a rectangular or triangular arrangement. The jet tube has two functions: one is the flow channel of the jet fluid; the other is to install a twisting element to force the jet fluid to flow axially while generating a rotational flow. The jet tube is a smooth straight tube with a diameter of 10% to 30% of the core tube diameter. The jet tube is flush with the inner wall of the core tube or extends a certain length inward, and the length range is 0%-30% of the inner diameter of the core tube. The extension length of the jet tube on the surface of the core tube is not greater than 50% of the gap between the reaction tube and the core tube.

[0020] Each jet tube is inserted with a twisting element. The diameter of the twisting element should ensure that its contour fits the inner wall of the jet tube, and the length is equal to or slightly shorter than the jet tube; the twisting element adopts a spiral twisted belt (twisting sheet) or a swirl element with other cross-sectional shapes, and its twist rate is determined according to the flow rate and physical properties of the jet fluid. The function of the twisting element is to form a rotating jet, and its structure can adopt a straight-line, three-pointed star, cross-shaped twisting sheet, etc. The twisting element is fixed to the inner wall of the jet tube by welding or bonding. The aspect ratio of the twisting element is ≤2 (the aspect ratio is the ratio of the axial length to the element diameter when twisted 180°). The surface of the twisting sheet should be smooth and flat, and the roughness should not be greater than 16μm. Under the action of the twisting element, the jet fluid is divided into two or more strands and flows spirally around the center of the jet tube, producing a suction effect on the spiral flow (cross flow) and a strong impact on the reaction tube wall.

[0021] The cross-flow inlet tube is installed tangentially to the reaction tube, that is, the axis of the cross-flow inlet tube is perpendicular to the axis of the reaction tube (4), and the outermost inner wall of the cross-flow inlet tube is tangential to the inner wall of the reaction tube; depending on the diameter of the reaction tube, one, two or more cross-flow inlet tubes can be used, each of which has the same specification and is evenly distributed in the same cross-section of the reaction tube. The cross-flow inlet tube connecting element is preferably a flange, and can also be directly connected by welding. The function of the cross-flow inlet tube is to force the reaction fluid (i.e., the lateral fluid) entering the annular space between the core tube and the reaction tube to produce a spiral flow around the axis of the reaction tube, and the average spiral angle of the induced spiral flow is φ Should not be greater than 60°, average helix angle φ The average circumferential tangential velocity V θm and the average axial velocity V zm Calculated, that is φ= Arctan V θm / V zm ).

[0022] According to the needs of reaction residence time and reaction effect, a certain space length should be left in the reaction tube behind the core tube. This section can be empty or add static mixing elements, such as Kenics, SX, SL and other structural elements. The function of this space is to maintain the mixing effect of the rotating jet impacting the spiral cross flow to ensure sufficient reaction residence time.

[0023] The function of the jacket is to take away or provide the heat released or required by the reaction process, so that the reaction process is in a relatively stable temperature state. The jacket uses a sleeve concentric with the reaction tube, and the diameter is 2 specifications larger than the reaction tube. Under the premise of meeting the welding requirements of the reaction tube wall, it is as close to the reaction tube length as possible. Example 1

[0024] The reaction tube is a stainless steel tube of φ159×4.5, and the core tube is a stainless steel tube of φ59×3. The cross-flow inlet tube uses two rotating opposite circular tubes with a specification of φ59×3. Its structure is as follows: Figure 8 The jet tubes are evenly distributed in 5 rows along the core tube axis, and 4 jet tubes are evenly distributed in each row along the circumference. The jet tubes in each row have the same orientation, that is, they are arranged in a rectangular shape. The arrangement of the jet tubes is as follows: Figure 2 The jet tube has a built-in straight-line twisting element. The assembly relationship between the twisting element and the jet tube and the structure of the twisting element are shown in Figure 4 and Figure 5 As shown. An empty tube is directly used behind the core tube as a mixing element to maintain the mixing effect. The cross-flow fluid enters the reaction tube through two cross-flow inlet tubes, and a spiral flow is formed in the annular cavity between the core tube and the reaction tube. After the jet fluid enters the core tube, it passes through each jet tube and is sprayed at high speed to the cross-flow fluid under the action of the twisting element, thereby realizing an efficient reaction process of cross-flow and jet. The reactor structure and flow characteristics of this embodiment are shown in FIG. Figure 1 shown. Example 2

[0025] The structure of this embodiment is basically the same as that of embodiment 1, except that the cross-flow inlet pipe adopts two rectangular cross-section pipes with a cross-sectional size of 60×30. The cross-flow inlet pipe adopts this structural form to increase the inlet area and inlet momentum, improve the swirl intensity of the cross-flow, and maintain a longer swirl state in the reaction tube. The cross-flow inlet pipe structure of this embodiment is shown in 9. Example 3

[0026] The structure of this embodiment is basically the same as that of embodiment 1, except that the twisting element adopts a three-pointed star structure (such as Figure 6 As shown). This type of twisting element can be used to divide the jet fluid into three streams, each with a 120° fan-shaped cross section, and the three jets rotate and flow around the axis of the jet tube. Example 4

[0027] The structure of this embodiment is basically the same as that of embodiment 1, except that: first, the twisting element adopts a cross-shaped structure (such as Figure 7 As shown), secondly, the jet tubes are arranged in a triangle, that is, adjacent rows of jet tubes are staggered at an angle of 45°. Example 5

[0028] The structure of this embodiment is basically the same as that of embodiment 1, except that the mixing element adopts Kenics element, whose aspect ratio is 2 and the number of elements is 4. After adopting Kenics mixing element, the reaction fluid can maintain a good mixing state, which is particularly suitable for fluids with high viscosity.

Claims

1. A tubular reactor with multiple rotating jets impacting spiral flows, characterized in that: The reactor comprises a core tube (1), a core tube fixing member (2), a cross-flow inlet tube (3), a reaction tube (4), a jet tube (5), a twisting element (6), a mixing element (7) and a jacket (8); the core tube (1) is fixed by welding with the core tube fixing member (2) and is coaxially inserted into the reaction tube (4); the outlet of the core tube (1) in the reaction tube (4) is sealed by welding with a blind plate; a plurality of through holes are arranged on the surface of the core tube (1), and the jet tubes (5) are fixed by welding in the through holes; the jet tubes (5) are installed flush with the inner surface of the core tube (1) or extend inward; each jet tube (5) is inserted into a twisting element (6), and the diameter of the twisting element (6) should be The profile thereof is ensured to be in close contact with the inner wall of the jet tube (5), and the length thereof is equal to the jet tube (5); the twisting element (6) is a spiral twisted ribbon-shaped swirl element, and the twist rate thereof is determined according to the flow velocity and physical properties of the jet fluid; the cross-flow inlet tube (3) is installed tangentially to the reaction tube (4), that is, the axis of the cross-flow inlet tube (3) is perpendicular to the axis of the reaction tube (4), and the outermost side of the inner wall of the cross-flow inlet tube (3) is tangential to the inner wall of the reaction tube (4); according to the different diameters of the reaction tube (4), one, two or more cross-flow inlet tubes (3) are used, and the specifications of the cross-flow inlet tubes (3) are the same and they are evenly distributed in the same cross section of the reaction tube (4).

2. A tubular reactor with multiple rotating jets impinging on spiral flows according to claim 1, characterized in that: The mixing element (7) added at the rear of the inner core tube (1) of the reaction tube (4) is a commercial static mixing element.

3. A tubular reactor with multiple rotating jets impinging on spiral flows according to claim 2, characterized in that: The mixing element (7) may be a static mixing element including Kenics, SX, SL, or directly use an empty tube.

4. A tubular reactor with multiple rotating jets impinging on spiral flows according to claim 3, characterized in that: The length of the mixing element (7) is determined according to the reaction residence time and the reaction effect.

5. The tubular reactor with multiple rotating jets impinging on spiral flows according to claim 1, characterized in that: The tubular reactor with multiple rotating jets impacting spiral flows is installed in a horizontal or vertical manner.

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