Dean vortex reverser suitable for low-net-flow continuous flow reaction and continuous flow system of Dean vortex reverser

Abstract

The invention discloses a Dean vortex reverser suitable for low net flow continuous flow reaction and a continuous flow system thereof. The continuous flow system comprises a feeding device, an oscillation device, a reactor body and a back pressure control device, the feeding device comprises a stirring batching kettle, a filter, a metering pump, a check valve, a stop valve and the like; the oscillation device is positioned between the feeding device and the reactor body and comprises an oscillation pump, an oscillation pipeline, a valve and the like; the reactor body comprises an elliptical reaction tube without a baffle structure, the elliptical reaction tube twists and spirals along the inner cylinder wall of the oil bath cavity to form an elliptical twisted spiral tube structure, reverse rotation of Dean vortexes is achieved in the flowing direction, the elliptical twisted spiral tube is clamped by the inner cylinder wall and the outer cylinder wall of the oil bath cavity, a twisted spiral oil heat exchange channel is formed, and the heat exchange efficiency is improved. Based on the dual effects of the Dean vortex reverser with the elliptical twisted spiral tube structure and the oscillatory flow, the radial cross-channel mixing capacity is effectively enhanced in a limited geometric space, the piston flow characteristic of the reactor is enhanced, and the low-net-flow continuous flow reactor is particularly suitable for low-net-flow continuous flow reaction requiring long reaction time.

Description

Technical Field

[0001] This invention belongs to the field of continuous flow reactor technology, and relates to a Dean vortex inverter and its continuous flow system suitable for low net flow continuous flow reactions. Background Technology

[0002] Process intensification (especially through continuous flow technology) aims to significantly improve the space-time yield and energy efficiency of reactors through methods such as equipment integration, reactor miniaturization, alternative reaction pathway screening, and continuous operation at higher temperatures, pressures, and concentrations. The fine chemical and pharmaceutical industries are the main application areas for continuous flow-oriented process intensification technologies. These industries commonly employ numerous batch processes, some of which are characterized by short operating cycles, relatively mild operating conditions, and small production scales, making them highly compatible with continuous flow processes. Microchannel mixers and plate serpentine channels have been applied to mixing miscible and immiscible systems, particularly suitable for reaction scenarios requiring near-plug flow characteristics and rapid transfer rates. However, for reaction systems with slower reaction rates, longer residence times, or those containing solid particles, small helical reactors or stirred tank reactors remain the primary options.

[0003] In a helical reactor, when the reactant velocity exceeds a critical value, the pressure gradient at the tube wall dominates the centrifugal force, causing the fluid on the upper and lower walls to flow inwards towards the inner wall, while the fluid in the center flows back towards the outer wall. This secondary flow manifests as a pair of counter-rotating vortices, known as Dean vortices, superimposed on the net mainstream motion. Multiple studies have shown that, utilizing the Dean vortex phenomenon, helical reactors in the laminar flow region can reduce axial diffusion compared to straight tubes. The greater frictional loss on the curved outer side translates into superior radial mixing, achieving characteristics similar to piston flow. However, existing research has confirmed that the axial dispersion performance of helical reactors is only superior to that of straight tubes when the Reynolds number Re > 300, setting a lower limit for the operating flow rate of helical reactors. For processes with long residence times, reactors with large aspect ratios are required, which presents limitations in practical applications. Furthermore, the fluid at the center of the Dean vortex can only achieve mass transfer through diffusion; the existence of such fluid retention zones leads to suboptimal mixing and axial dispersion performance.

[0004] Therefore, developing a quasi-plugg flow reactor that is compact, easy to maintain, and suitable for reaction systems with long residence times and containing solid particles is of great research and application significance. Summary of the Invention

[0005] In view of this, the purpose of this invention is to propose a Dean vortex inverter and its continuous flow system suitable for low net flow continuous flow reactions. Based on the Dean vortex inverter with an elliptical twisted helical tube structure and the dual effect of oscillating flow, it effectively enhances the radial cross-channel mixing capacity within a limited geometric space and enhances the piston flow characteristics of the reactor. It is particularly suitable for low net flow continuous flow reactions with long reaction time requirements.

[0006] Based on the above objectives, the present invention provides a Dian vortex inverter and its continuous flow system suitable for low net flow continuous flow reactions, including: a feeding device, an oscillation device, a reactor body, a back pressure control device, a heat transfer oil cooling and heating integrated machine, heat transfer oil pipelines, etc. The feeding device includes a batching and mixing unit, a filtration unit, a metering unit, a check valve, a preheating period, and several shut-off valves; the filtration unit includes a dual-path filter cartridge, which can be replaced online through front and rear valves. The oscillation device includes an oscillation pump, an oscillation preheater, and a control shut-off, and a waste liquid collection tank is connected downstream of the oscillation device. The reactor body includes a reaction liquid inlet, a reaction liquid outlet, a heat transfer oil inlet, a heat transfer oil outlet, and a reaction tube without a baffle structure. The reaction tube has an elliptical cross-section. The reaction tube is twisted and spiraled along the inner wall of the oil bath cavity to form an elliptical twisted spiral tube structure, which realizes the reversal of the Dean vortex in the flow direction. The inner and outer walls of the oil bath cavity clamp the elliptical twisted spiral tube to form a twisted spiral oil heat exchange channel. A safety pressure relief valve and a four-way valve for manifolding are installed upstream of the reactor body. The feeding device and the oscillation device are respectively connected to the four-way valve and then enter the reactor body. A back pressure control device is connected downstream of the reactor body to control the reaction pressure inside the reactor body.

[0007] Preferably, the reaction tube has an elliptical cross-section, with the long side A ranging from 5 to 50 mm, the short side B ranging from 1 to 30 mm, the helical diameter D ranging from 10 to 500 mm, the pitch H ranging from 10 to 500 mm, and the twist number T within one pitch ranging from 2 to 30. The reaction tube root can be repeatedly wound in multiple units to adapt to different reaction process requirements. The reaction tube material can be austenitic stainless steel or Hastelloy, and to prevent particles from adhering to the tube wall, the tube wall needs to be polished to achieve a mirror finish.

[0008] Preferably, the oscillation amplitude of the oscillation pump is adjustable from 0 to 100 mm, and the oscillation frequency is adjustable from 0 to 20 Hz.

[0009] The beneficial effects of this invention are: (1) Based on the dual enhancement of Dean's vortex reversal and oscillating flow, the radial mixing and piston flow characteristics under low net flow rate are significantly improved: The present invention optimizes the problem of insufficient mixing efficiency and poor backmixing controllability of traditional continuous flow reactors under low net flow rate conditions from the perspective of fluid dynamics by realizing the synergistic coupling effect of Dean's vortex reversal effect and oscillating flow through the elliptical twisted spiral tube structure. Under low net flow rate conditions, the fluid in conventional tubular reactors is mainly in a laminar state, and radial mass transfer is completed only by molecular diffusion. The mixing speed is slow and the uniformity is poor, which makes it difficult to meet the process requirements of rapid reaction and long residence time. In this scheme, when the fluid flows through the elliptical reaction tube arranged in a twisted spiral along the inner wall of the oil bath chamber, the flow channel cross section and flow direction change continuously, which can induce stable and periodically reversing Dean's vortex. While the fluid flows along the tube axis, it forms a strong radial disturbance across the channel, breaks the laminar boundary layer, and greatly enhances the radial mixing efficiency. Building upon this, the controllable oscillating flow provided by the front-end oscillation device further applies reciprocating disturbances to the fluid, creating a superimposed and enhanced effect with the Dean vortex reversal, enabling efficient mixing of the fluid at both the micro and mesoscales. This dual-action mechanism significantly suppresses axial backmixing, greatly improving the reactor's plug flow characteristics. This allows the reactor to maintain a stable and uniform reaction environment even under harsh conditions of low net flow rate and long reaction time, effectively improving reaction conversion, selectivity, and product consistency. (2) The present invention adopts an integrated structure of a baffle-free elliptical reaction tube with a twisted spiral arrangement and an inner and outer cylinder wall clamped oil bath cavity, which simultaneously achieves compact reactor structure and high efficiency of heat transfer process within a limited geometric space. The reactor body adopts an elliptical reaction tube with a baffle-free structure, which is twisted spirally formed along the inner cylinder wall of the oil bath cavity, eliminating the problems of flow dead zone, coking, blockage and cleaning difficulties caused by internal components; at the same time, the inner cylinder wall and the outer cylinder wall of the oil bath cavity directly clamp the elliptical twisted spiral tube, forming a twisted spiral oil heat exchange channel that fits tightly with the reaction tube, and the heat exchange medium and the outer wall of the reaction tube achieve full circumferential and high fit contact, which greatly increases the effective heat exchange area. Attached Figure Description

[0010] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only for this invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0011] Figure 1 This is a schematic diagram of the reactor body structure of a Dian vortex inverter and its continuous flow system, which is suitable for low net flow rate continuous flow reactions as described in this invention. Figure 2This is a schematic diagram and characteristic geometric parameters of an elliptical twisted helical tube structure and its continuous flow system for a Dian vortex inverter suitable for low net flow continuous flow reactions, as described in this invention. Figure 3 This is a schematic diagram of the reactor body cross-section of a Dean vortex inverter suitable for low net flow continuous flow reactions and its continuous flow system, as described in this invention, and a schematic diagram of Dean vortex inversion caused by an elliptical twisted helical tube. Figure 4 This is a process flow diagram of a Dian vortex inverter and its continuous flow system suitable for low net flow continuous flow reactions, as described in this invention.

[0012] The diagram is marked as follows: 1. Reactor body; 101. Reaction liquid inlet; 102. Reaction liquid outlet; 103. Reaction tube; 104. Heat transfer oil outlet; 105. Heat transfer oil inlet; 106. Oil heat exchange channel; 107. Outer cylinder wall; 108. Inner cylinder wall; 109. Contact point between reaction tube and outer cylinder wall; 110. Contact point between reaction tube and inner cylinder wall; 2. Vibrating pump; 301. First metering pump; 302. Second metering pump; 401. First batching stirring vessel; 402. Second batching mixing vessel; 501, First filter device; 502, Second filter device; 601~606, Shut-off valve; 701, First check valve; 702, Second check valve; 801, First preheater; 802, Second preheater; 803, Oscillating preheater; 9, Thermal oil cooling and heating integrated machine; 10, Thermal oil pipeline; 11, Back pressure control device; 12, Reaction outlet; 13, Waste liquid collection tank; 14, Four-way valve; 15, Safety pressure relief valve. Detailed Implementation To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments.

[0013] It should be noted that, unless otherwise defined, the technical or scientific terms used in this invention should have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The terms "first," "second," and similar terms used in this invention do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0014] like Figure 4 As shown, a specific embodiment of the present invention provides a vertical shaft support structure suitable for magnetic coupling seals and its high-temperature pump system, characterized in that it includes: a feeding device, an oscillation device, a reactor body (1), a back pressure control device (11), and a heat transfer oil cooling and heating integrated machine (9), a heat transfer oil pipeline (10), etc.; the feeding device includes a batching and stirring kettle (401, 402), a filtration device (501, 502), a metering pump (301, 302), a check valve (701, 702), a preheating stage (801, 802), and several shut-off valves (601, 602, 603, 604); the filtration device (501, 502) includes a dual-path filter element, which can be replaced online by controlling the front and rear valves; the oscillation device includes an oscillation pump (2), an oscillation preheater (803), and a control shut-off valve (605, 606), and a waste liquid collection tank (13) is connected downstream of the oscillation device; as Figure 1 The reactor body (1) shown includes a reaction liquid inlet (101), a reaction liquid outlet (102), a heat transfer oil inlet (105), a heat transfer oil outlet (104), and a reaction tube (103) without a baffle structure. The reaction tube (103) has an elliptical cross section. The reaction tube (103) is twisted and spiraled along the inner wall (108) of the oil bath chamber to form an elliptical twisted spiral tube structure, realizing the reversal of the Dean vortex in the flow direction. The inner wall (108) and outer wall (107) of the oil bath chamber clamp the elliptical twisted spiral tube (103) to form a twisted spiral oil heat exchange channel (106). A safety pressure relief valve (15) and a four-way valve (14) for confluence are installed upstream of the reactor body. The feeding device and the oscillation device are connected to the four-way valve and then enter the reactor body (1). A back pressure control device (11) is connected downstream of the reactor body (1) to control the reaction pressure inside the reactor body (1).

[0015] In specific implementation cases, such as Figure 3 As shown, the inner wall (108) and outer wall (107) of the oil bath chamber clamp the elliptical twisted spiral tube to form several fulcrums, including the contact point between the reaction tube and the outer wall (109) and the contact point between the reaction tube and the inner wall (110), forming a twisted spiral oil heat exchange channel (106) that fits tightly with the reaction tube. The heat exchange medium and the outer wall of the reaction tube achieve full circumferential and high fit contact, greatly increasing the effective heat exchange area and eliminating the gaps and heat transfer dead angles that exist in traditional jacketed heat exchange.

[0016] In specific implementation cases, such as Figure 2 The reaction tube (103) has an elliptical cross-section, with the long side A of the ellipse ranging from 5 to 50 mm, the short side B ranging from 1 to 30 mm, the spiral diameter D ranging from 10 to 500 mm, the pitch H ranging from 10 to 500 mm, and the twist number T within one pitch ranging from 2 to 30.

[0017] In specific implementation cases, such as Figure 1 The reaction tube (103) can be made of austenitic stainless steel or Hastelloy, and the tube wall needs to be polished to achieve a mirror effect in order to prevent particles from adhering to the tube wall.

[0018] In some optional specific embodiments, such as Figure 1 As shown, the reaction tube (103) can be repeatedly wound into multiple units to adapt to different reaction process requirements.

[0019] In specific implementation cases, such as Figure 4 The oscillation amplitude of the oscillation pump (2) is adjustable from 0 to 100 mm, and the oscillation frequency is adjustable from 0 to 20 Hz.

[0020] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the invention (including the claims) is limited to these examples; within the framework of the invention, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of the different aspects of the invention as described above, which are not provided in the details for the sake of brevity.

[0021] This invention is intended to cover all such substitutions, modifications, and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A Dean vortex inverter and its continuous flow system suitable for low net flow rate continuous flow reactions, characterized in that, include: Feeding device, oscillation device, reactor body (1), back pressure control device (11), heat transfer oil cooling and heating integrated machine (9), heat transfer oil pipeline (10), etc.; The feeding device includes a batching and mixing tank (401, 402), a filtration device (501, 502), a metering pump (301, 302), a check valve (701, 702), a preheating valve (801, 802), and several shut-off valves (601, 602, 603, 604); the filtration device (501, 502) includes a dual-path filter element, which can be replaced online through the control of the front and rear valves; The oscillation device includes an oscillation pump (2), an oscillation preheater (803), and control shut-off valves (605, 606). A waste liquid collection tank (13) is connected downstream of the oscillation device. The reactor body (1) includes a reaction liquid inlet (101), a reaction liquid outlet (102), a heat transfer oil inlet (105), a heat transfer oil outlet (104), and a reaction tube (103) without a baffle structure. The reaction tube (103) has an elliptical cross section. The reaction tube (103) is twisted and spiraled along the inner wall (108) of the oil bath chamber to form an elliptical twisted spiral tube structure, realizing the reversal of the Dean vortex in the flow direction. The inner wall (108) and outer wall (107) of the oil bath chamber clamp the elliptical twisted spiral tube (103) to form a twisted spiral oil heat exchange channel (106). A safety relief valve (15) and a four-way valve (14) for merging are installed upstream of the reactor body. The feeding device and the oscillating device are connected to the four-way valve and merge into the reactor body (1). Downstream of the reactor body (1), a back pressure control device (11) is connected to control the reaction pressure inside the reactor body (1).

2. The Dean vortex inverter and its continuous flow system suitable for low net flow rate continuous flow reactions according to claim 1, characterized in that, The reaction tube (103) has an elliptical cross-section, with the long side A of the ellipse ranging from 5 to 50 mm, the short side B ranging from 1 to 30 mm, the spiral diameter D ranging from 10 to 500 mm, the pitch H ranging from 10 to 500 mm, and the twist number T within one pitch ranging from 2 to 30.

3. The Dean vortex inverter and its continuous flow system suitable for low net flow rate continuous flow reactions according to claim 1, characterized in that, The reaction tube (103) can be repeatedly wound in multiple units to adapt to different reaction process requirements.

4. The Dean vortex inverter and its continuous flow system suitable for low net flow rate continuous flow reactions according to claim 1, characterized in that, The reaction tube (103) can be made of austenitic stainless steel or Hastelloy, and the tube wall needs to be polished to achieve a mirror effect in order to prevent particles from adhering to the tube wall.

5. The Dean vortex inverter and its continuous flow system suitable for low net flow rate continuous flow reactions according to claim 1, characterized in that, The oscillation amplitude of the oscillation pump (2) is adjustable from 0 to 100 mm, and the oscillation frequency is adjustable from 0 to 20 Hz.

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