A granular packed fixed bed

Abstract

The present invention discloses a particle-packed fixed bed, which includes solid particles, unit-type enhanced heat transfer parts, a mesh limiter, a fairing, and a fixed bed housing. The unit-type enhanced heat transfer parts and the solid particles are arranged alternately along the axial direction of the fixed bed housing. The unit-type enhanced heat transfer parts are centrally symmetric columnar structures made of high thermal conductivity materials. The unit-type enhanced heat transfer parts have voids in the axial direction to allow fluid to pass through axially. Vortex generators are provided on the surfaces of the unit-type enhanced heat transfer parts parallel to the axial direction. And in the axial projection of the unit-type enhanced heat transfer parts, the outermost boundary in the radial direction thereof is in close fit with the inner side of the fixed bed housing. The present invention is applied to the field of fixed beds, can enhance the heat transfer efficiency of the fixed bed, quickly realize the disassembly and assembly of the particle-packed fixed bed, improve the orderliness of the particle-packed fixed bed, reduce the flow loss in the particle bed, extend the service life of the particles, and achieve more efficient industrial production.

Description

Technical Field

[0001] The present invention relates to the technical fields of reactors and enhanced heat transfer technology. It can conveniently and quickly construct a particle-packed fixed bed and enhance its heat transfer performance, achieving functional purposes such as efficient heat transfer, energy storage, and chemical reactions in the particle-packed fixed bed, and particularly relates to a particle-packed fixed bed. Background Art

[0002] The particle-packed fixed bed is a common reactor in the fields of nuclear energy, petrochemical industry, energy storage, renewable energy, and dust removal and purification, such as ammonia synthesis towers, sulfur dioxide contact oxidizers, solar collectors, and gas purifiers. The particle-packed fixed bed has the advantages of being structurally compact, having a large internal specific surface area, strong flow disturbance, simple design and manufacture, and stable operation, and is mainly used to achieve gas (liquid)-solid phase reactions and gas purification, etc. The particle-packed fixed bed can be divided into an ordered particle-packed fixed bed and a disordered particle-packed fixed bed according to the particle packing method therein. The disordered particle-packed fixed bed is widely used in industrial production due to its advantages of simple structure, easy implementation, and low cost; the ordered particle-packed fixed bed usually includes a grid channel particle packing structure and an ideal particle packing structure, but its application is limited due to the complexity of the structure. In the particle-packed fixed bed, its heat transfer performance is relatively crucial. Good heat transfer performance can enable the heat source outside the particle-packed fixed bed to be efficiently transferred to its interior, enabling the heat to complete the corresponding efficiency within the particle-packed fixed bed. However, since its interior is made of a large number of solid particles with low thermal conductivity, the heat transfer performance of the particle-packed fixed bed is poor, which greatly limits its production efficiency and service life.

[0003] Therefore, for the particle-packed fixed bed, there is an urgent need for a simple and feasible structure with enhanced heat transfer to solve the technical deficiencies of the particle-packed fixed bed. Summary of the Invention

[0004] In view of the limitations and deficiencies of the above research, the present invention proposes a particle-packed fixed bed on this basis, which has a simple manufacturing process, is structurally compact, has strong heat transfer ability, reduces wall effects, and can be quickly modified on the existing particle-packed fixed bed.

[0005] The technical solution of the present invention is realized as follows:

[0006] The specific structure of a particle-packed fixed bed of the present invention includes solid particles, unit-type enhanced heat transfer parts, a mesh limiter, a fairing, and a fixed bed housing. The mesh limiter and the fairing are located at the inlet and outlet positions on the fixed bed housing. The unit-type enhanced heat transfer parts and the solid particles are inside the fixed bed housing. The unit-type enhanced heat transfer parts and the solid particles are arranged alternately along the axial direction of the fixed bed housing, and the positions of the solid particles and the unit-type enhanced heat transfer parts do not overlap, and the solid particles do not enter the gaps of the unit-type enhanced heat transfer parts.

[0007] The fixed bed shell is a circular tubular structure, and the unit-type enhanced heat transfer part is a centrally symmetric columnar structure made of a high thermal conductivity material. The unit-type enhanced heat transfer part is coaxial with the fixed bed shell. The unit-type enhanced heat transfer part has voids in the axial direction to allow fluid to pass through axially. In the axial projection of the unit-type enhanced heat transfer part, its outermost boundary in the radial direction is in close fit with the inner side of the fixed bed shell, and this outermost boundary in the radial direction is located on the concentric circle of the axial projection of the fixed bed shell. The diameter of this concentric circle is 0.98 - 1 times the inner diameter of the fixed bed shell. The unit-type enhanced heat transfer part can be freely loaded and unloaded inside the fixed bed shell; after the unit-type enhanced heat transfer part is placed into the fixed bed shell, it can be automatically positioned under the action of the inner side of the fixed bed shell and solid particles without manual adjustment. The structure of the unit-type enhanced heat transfer part is an enhanced heat transfer structure, such as: fin structure, pin column structure, foam structure, etc.

[0008] The shape of the solid particles can be spherical, quasi-spherical, petal-shaped, etc., and its characteristic diameter is 0.1 - 1 times the characteristic size of the fixed bed. The solid particles are randomly distributed in the space inside the fixed bed shell, outside the unit-type enhanced heat transfer part, and between the inlet and outlet mesh limiters.

[0009] By changing the number, shape, size of the solid particles and the number, shape, and length size of the unit-type enhanced heat transfer parts, different stacking forms of this kind of particle-packed fixed bed can be formed. At the same time, connecting the above-mentioned particle-packed fixed beds in series or parallel can form multiple groups of particle-packed fixed beds of different scales.

[0010] The present invention has the following advantages compared with the prior art

[0011] 1. The enhanced heat transfer part is a centrally symmetric columnar structure made of a high thermal conductivity material, which is coaxial with the fixed bed shell, enabling rapid installation. In the axial projection of the unit-type enhanced heat transfer part, its outermost boundary in the radial direction is in close fit with the inner side of the fixed bed shell, increasing the radial heat conduction ability of the particle-packed fixed bed. And the unit-type enhanced heat transfer part has voids in the axial direction to allow fluid to pass through axially, increasing the convective heat transfer area while rectifying the fluid. Compared with the traditional particle-packed fixed bed, this particle-packed fixed bed has the effects of enhancing heat transfer and improving fluidity.

[0012] 2. This particle-packed fixed bed improves the order degree of the particles, reduces the internal flow loss, increases the temperature uniformity inside the particle-packed fixed bed, extends the service life of the particles, realizes more efficient industrial production (flow heat transfer), weakens the influence of the wall effect in the fixed bed, and enhances the safety inside the reactor.

[0013] 3. The manufacturing process of the particle-packed fixed bed is simple and its structure is compact. The unit-type enhanced heat transfer parts can be freely loaded and unloaded within the original fixed bed shell, and convenient and rapid enhanced transformation can be achieved on the structure of the original particle-packed fixed bed, so as to quickly realize efficient production. Brief Description of the Drawings

[0014] Figure 1(a) is a schematic diagram of the particle-packed fixed bed - 1 with the unit-type enhanced heat transfer part - a placed therein according to the present invention.

[0015] Figure 1(b) is a schematic diagram of the particle-packed fixed bed - 2 with the unit-type enhanced heat transfer part - b placed therein according to the present invention.

[0016] Figure 1(c) is a schematic diagram of the particle-packed fixed bed - 3 with a different particle arrangement mode from that in Figure 1(a) and with the unit-type enhanced heat transfer part - a placed therein according to the present invention.

[0017] Figure 2(a) is a left view of the particle-packed fixed bed - 1 according to the present invention.

[0018] Figure 2(b) is a schematic diagram of the section A - A of Figure 2(a).

[0019] Figure 2(c) is a front view of the particle-packed fixed bed - 1 according to the present invention.

[0020] Figure 2(d) is a schematic diagram of the section B - B of Figure 2(c).

[0021] Figure 3(a) is a left view of the particle-packed fixed bed - 2 according to the present invention.

[0022] Figure 3(b) is a schematic diagram of the section A - A of Figure 3(a).

[0023] Figure 3(c) is a front view of the particle-packed fixed bed - 2 according to the present invention.

[0024] Figure 3(d) is a schematic diagram of the section B - B of Figure 3(c).

[0025] Figure 4(a) is a schematic diagram of the unit-type enhanced heat transfer part - a in the present invention.

[0026] Figure 4(b) is a schematic diagram of the unit-type enhanced heat transfer part - b in the present invention.

[0027] Figure 5(a) is a front view of the unit-type enhanced heat transfer part - a in the present invention.

[0028] Figure 5(b) is a front view of the unit-type enhanced heat transfer part - b in the present invention.

[0029] Figure 6 It is a schematic diagram of a fairing.

[0030] Figure 7It is a schematic diagram of a mesh limiter.

[0031] Figure 8(a) is a schematic diagram of a traditional ordered particle-packed fixed bed - 4.

[0032] Figure 8(b) is a schematic diagram of a particle-packed fixed bed - 5 with the unit type enhanced heat transfer part - a described in the present invention. At the same time, to verify the enhanced heat transfer and hydrogen production effects of the particle-packed fixed bed in the present invention, this schematic diagram is a CFD simulation physical model of methane steam reforming in the particle-packed fixed bed.

[0033] Figure 9(a) is the simulation result: a schematic diagram of the average outlet temperature of the particle-packed fixed bed - 3 under different wall temperatures.

[0034] Figure 9(b) is the simulation result: a schematic diagram of the hydrogen mass at the outlet of the particle-packed fixed bed - 3 under different wall temperatures.

[0035] In the figure: (1) is the fairing, (2) is the mesh limiter, (3) is the fixed bed shell, (4) is the solid particles, (5) is the unit type enhanced heat transfer part - a, (6) is the unit type enhanced heat transfer part - b, and (7) is the vortex generator. Specific implementation mode

[0036] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative efforts belong to the scope of protection of the present invention.

[0037] As shown in Figure 1(a), the particle-packed fixed bed - 1 of the present invention is composed of: a fairing (1), a mesh limiter (2), a fixed bed shell (3), solid particles (4), a unit type enhanced heat transfer part - a (5), and a vortex generator (7). The fixed bed shell (3) is a circular tubular structure. The solid particles (4) and the unit type enhanced heat transfer part - a (5) are arranged alternately along the axial direction of the fixed bed shell in the fixed bed shell (3), and their positions do not overlap. The solid particles (4) will not enter the gaps of the unit type enhanced heat transfer part - a (5). The unit type enhanced heat transfer part - a (5) is fixed to the fixed bed shell (3) and the solid particles (4) in a mutually extruded manner. The mesh limiter (2) is located at the inlet and outlet of the fixed bed shell (3) and is used to limit the positions of the solid particles (4) and the unit type enhanced heat transfer part - a (5) in the fixed bed shell. The fairing (1) is located outside the mesh limiter (2) at the inlet and outlet and serves to connect the pipeline and the particle-packed fixed bed.

[0038] As shown in Fig. 1(b), another specific embodiment of the present invention is the particle-packed fixed bed - 2, which consists of a fairing (1), a mesh limiter (2), a fixed bed housing (3), solid particles (4), a unitary enhanced heat transfer part - b (6), and a vortex generator (7). By comparing with Fig. 1(a), the difference between the particle-packed fixed bed - 2 and the particle-packed fixed bed - 1 is the difference between the used unitary enhanced heat transfer part - b (6) and the unitary enhanced heat transfer part - a (5). As shown in Figs. 4(a), (b) and Figs. 5(a), (b), the unitary enhanced heat transfer part - a (5) and the unitary enhanced heat transfer part - b (6) are centrosymmetric finned columnar structures. In the unitary enhanced heat transfer part - a (5) and the unitary enhanced heat transfer part - b (6), there are voids in the axial direction to allow the fluid to pass through axially, and vortex generators (7) are arranged on the surfaces parallel to the axial direction to enhance the fluid disturbance. As shown in Figs. 1(a), (b), Fig. 2(d), and Fig. 3(d), the outermost radial boundaries of the unitary enhanced heat transfer part - a (5) and the unitary enhanced heat transfer part - b (6) are in close fit with the inner side of the fixed bed housing, and the outermost radial boundary is located on the concentric circle of the axial projection of the fixed bed housing. The diameter of this concentric circle is 0.98 - 1 times the inner diameter of the fixed bed housing, and the unitary enhanced heat transfer part can be freely loaded and unloaded in the fixed bed housing.

[0039] When the particle-packed fixed bed of the present invention is working, the fluid first flows into the particle-packed fixed bed through the fairing (1) from the pipeline, and then enters the fixed bed housing (3) through the mesh limiter (2). When the fluid contacts the solid particles (4), corresponding physical or chemical processes occur and heat is consumed. When the fluid flows through the unitary enhanced heat transfer part - a (5) or the unitary enhanced heat transfer part - b (6), due to its high thermal conductivity and the flow disturbance brought by the vortex generator (7), the heat transfer effect of the fluid is enhanced. The unitary enhanced heat transfer part - a (5) or the unitary enhanced heat transfer part - b (6) replenishes heat to the fluid. The fluid alternately flows through the solid particles (4) and the unitary enhanced heat transfer part in the fixed bed housing (3) to complete the corresponding physical or chemical processes, and then the fluid flows out of the fixed bed housing (3) and enters the pipeline again through the mesh limiter (2) and the fairing (1).

[0040] As shown in Fig. 1(c), another specific embodiment of the present invention is the particle-packed fixed bed - 3. It has the same composition as the particle-packed fixed bed - 1, and the difference lies in the arrangement mode of the solid particles (4) and the unitary enhanced heat transfer part - a (5). The specific arrangement mode can be adjusted according to actual industrial applications. The shape of the solid particles (4) can be spherical, quasi-spherical, petal-shaped, etc.; the characteristic diameter of the solid particles (4) is 0.1 - 1 times the characteristic size of the fixed bed housing (3), and the specific shape and size can be selected according to actual industrial applications.

[0041] Under normal circumstances, the heat source is located outside the fixed bed of particle accumulation. Heat is transferred into the fixed bed of particle accumulation through the outer shell (3) of the fixed bed. In the physical or chemical process where the fluid acts on the surface of solid particles, heat is consumed. Since the unit-type enhanced heat transfer part is made of a material with high thermal conductivity and its outer boundary fits tightly with the outer shell (3) of the fixed bed, this unit-type enhanced heat transfer part enhances the ability of heat to transfer from the outer shell (3) of the fixed bed into the fixed bed of particle accumulation. Moreover, the unit-type enhanced heat transfer part increases the heat transfer area in contact with the fluid, and the vortex generator (7) on its parallel axial surface enhances the flow disturbance. Therefore, the addition of the unit-type heat transfer part strengthens the heat transfer ability of the fixed bed of particle accumulation described in the present invention. When the fluid flows through the unit-type enhanced heat transfer part, heat is replenished. When the solid particles (4) and the unit-type enhanced heat transfer part are arranged alternately, the fluid can maintain a relatively high average temperature in the fixed bed of particle accumulation described in the present invention, and the overall efficiency is improved.

[0042] To verify the strengthening effect of the fixed bed of particle accumulation described in the present invention, the CFD software is used to perform simulation calculations on the methane steam reforming reaction in the fixed bed of particle accumulation. Figure 8 is a schematic diagram of the physical model used in the CFD simulation. As shown in Figure 8(a), it is a common ordered fixed bed of particle accumulation, and as shown in Figure 8(b), it is the fixed bed of particle accumulation - 4 described in the present invention. The CFD simulation compares the outlet temperature and the outlet hydrogen mass flow rate of the common fixed bed of particle accumulation and the fixed bed of particle accumulation described in the present invention.

[0043] Figure 8 shows the result diagram of the methane steam reforming reaction in the fixed bed of particle accumulation by CFD simulation. In Figure 8(a), the average outlet temperature of the common fixed bed of particle accumulation and the fixed bed of particle accumulation - 4 described in the present invention is compared under different wall temperatures. In Figure 8(b), the outlet hydrogen mass flow rate of the common fixed bed of particle accumulation and the fixed bed of particle accumulation - 4 described in the present invention is compared under different wall temperatures. The results show that the average outlet temperature of the fixed bed of particle accumulation - 4 described in the present invention is increased by up to 8K at most, and the outlet hydrogen mass flow rate is increased by up to 56% at most.

[0044] The enhanced heat transfer effect of the fixed bed of particle accumulation described in the present invention is verified. This kind of fixed bed of particle accumulation can enhance heat transfer by adding unit-type enhanced heat transfer parts without changing the structure of the outer shell of the original fixed bed of particle accumulation. The fixed bed of particle accumulation with this structure has obvious effects, is simple and easy to implement, and has relatively low time and money costs in engineering applications, and has good application prospects.

Claims

1. A particle-packed fixed bed, comprising solid particles, unit-type enhanced heat transfer parts, a mesh limiter, a fairing, and a fixed bed housing. The mesh limiter and the fairing are located at the inlet and outlet positions on the fixed bed housing. The unit-type enhanced heat transfer parts and the solid particles are inside the fixed bed housing. It is characterized in that, The unit-type enhanced heat transfer parts and solid particles are arranged alternately along the axial direction of the fixed bed shell, and the positions of the solid particles and the unit-type enhanced heat transfer parts do not overlap. The solid particles do not enter the voids of the unit-type enhanced heat transfer parts. The solid particles are randomly distributed in the space inside the fixed bed shell, outside the unit-type enhanced heat transfer parts, and between the inlet and outlet mesh limiters. The unit-type enhanced heat transfer part is a centrosymmetric columnar structure made of a high thermal conductivity material, and the unit-type enhanced heat transfer part is coaxial with the fixed bed shell. The unit-type enhanced heat transfer part has voids in the axial direction to allow the fluid to pass through axially. Vortex generators are provided on the surface of the unit-type enhanced heat transfer part parallel to the axial direction. In the axial projection of the unit-type enhanced heat transfer part, its outermost boundary in the radial direction is in close fit with the inner side of the fixed bed shell, and the outermost boundary in the radial direction is located on a concentric circle of the axial projection of the fixed bed shell. The diameter of the concentric circle is 0.98 - 1 times the inner diameter of the fixed bed shell. The unit-type enhanced heat transfer part can be freely loaded and unloaded in the fixed bed shell.

2. A granular packed fixed bed according to claim 1, characterized in that: After the unit-type enhanced heat transfer part is placed into the fixed bed shell, the unit-type enhanced heat transfer part can be automatically positioned under the action of the inner side wall surface of the fixed bed shell and the solid particles without manual adjustment.

3. A particle-packed fixed bed according to claim 1, characterized in that: The structure of the unit-type enhanced heat transfer part is a heat transfer enhancement structure, a fin structure, a pin fin structure, or a foam structure.

4. A particle-packed fixed bed according to claim 1, characterized in that: The shape of the solid particles is spherical, quasi-spherical, or petal-shaped.

5. A particle-packed fixed bed according to claim 1, characterized in that: The characteristic diameter of the solid particles is 0.1 - 1 times the characteristic size of the fixed bed.

6. A particle-packed fixed bed according to claim 1, wherein: The mesh limiter restricts the positions of the solid particles or the unit-type enhanced heat transfer parts at the inlet and outlet of the fixed bed while allowing the fluid to pass through the mesh limiter freely.

7. A particle-packed fixed bed according to claim 1, characterized in that: The fairing is located at the inlet and outlet of the fixed bed shell to connect the pipeline and the particle-packed fixed bed.

8. A particulate packed fixed bed according to claim 1, wherein: By changing the number, shape, size of the solid particles and the number, shape, and length size of the unit-type enhanced heat transfer parts, different stacking forms of the particle-packed fixed bed can be formed. At the same time, by connecting the above particle-packed fixed beds in series or in parallel, multiple groups of particle-packed fixed beds with different scales can be formed.

9. A particle-packed fixed bed according to claim 1, wherein: The fixed bed shell is a circular tubular structure.

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