Method and facility for heat transfer between a granular material and a fluid

Abstract

The invention relates to a method for heat transfer between a granular material (14) capable of forming a moving bed and a fluid (15), the method comprising filling a cylindrical chamber (2) with the granular material (14), the longitudinal axis (XX') of which cylindrical chamber extends horizontally in its configuration of use, supplying fluid to the chamber (2) via at least one cylindrical fluid-receiving tube (3) arranged at least partially inside the chamber (2), and rotating the chamber (2) about an axis coincident with the longitudinal axis (XX') of the chamber (2). The tube (3) is coaxial with the longitudinal axis (XX') of the chamber (2) and leads, at each of its ends, out of the chamber (2) so as to be able to be connected to a fluid circulation circuit (5), and the filling of the chamber (2) with the granular material (14) involves filling up to a filling height (H) comprised within the height range defined by the formula: R + a x R1, where R corresponds to the inner radius of the cylindrical chamber (2) and R1 corresponds to the inner radius of the cylindrical fluid-receiving tube (3), and where a is between 0 and 1.

Description

Description Title of the invention: METHOD AND INSTALLATION FOR HEAT TRANSFER BETWEEN A GRANULAR MATERIAL AND A FLUID

[0001] The present invention relates to a method and installation for heat transfer between a granular material suitable for forming a moving bed and a fluid.

[0002] It relates in particular to a heat transfer process between a granular material capable of forming a moving bed and a fluid, said process comprising: in a configuration known as the use of a cylindrical enclosure in which the longitudinal axis of said enclosure extends horizontally - a filling of said enclosure with a volume of granular material corresponding to the mobile bed to be formed, - a fluid supply to said enclosure via at least one cylindrical fluid receiving tube disposed at least partially inside the enclosure and - a rotational drive of said enclosure around an axis coinciding with the longitudinal axis of the enclosure.

[0003] It should be noted that granular material here refers to a collection of non-cohesive particles interacting mechanically. These particles are capable of forming a moving bed under the effect of rotation. In other words, this granular material is said to be in bulk.

[0004] Moving bed heat exchangers, in which heat transfer occurs between granular material and a fluid circulating in at least one tube within the enclosure, are well-known. These heat exchangers are increasingly being studied due to the large number of industries that have access to granular material. Such heat exchangers can be used to cool or heat the fluid from the granular material, or conversely, to cool or heat the granular material from the fluid. However, the heat exchanger solutions developed to date are expensive, energy-intensive, and not optimized.

[0005] One aim of the invention is to propose a process and installation for heat transfer of the aforementioned type which allows optimal heat transfer between the granular material and the fluid without compromising the simplicity of the process and installation and the relative energy efficiency of the installation.

[0006] To this end, the invention relates to a method of heat transfer between a granular material capable of forming a moving bed and a fluid, said method comprising: in a configuration known as the use of a cylindrical enclosure in which the longitudinal axis of said enclosure extends horizontally - filling said enclosure with a volume of granular material corresponding to the mobile bed to be formed, - a fluid supply to said enclosure via at least one cylindrical fluid receiving tube disposed at least partially inside the enclosure and - a rotational drive of said enclosure around an axis coinciding with the longitudinal axis of the enclosure, characterized in that the cylindrical fluid receiving tube is a fixed tube coaxial with the longitudinal axis of rotation of the enclosure which opens, at each of its ends, to the outside of the enclosure in order to be able to be connected to a fluid circulation circuit and in that the volume of granular material of the cylindrical enclosure used to form the moving bed corresponds to a filling height in granular material of the enclosure included within the range of heights defined by the formula: R + ax R1 with R corresponding to the inner radius of the cylindrical enclosure and R1 to the inner radius of the cylindrical fluid receiving tube and a being between 0 and 1, this filling height corresponding to the level of granular material in the enclosure in the leveled state of the granular material distributed homogeneously in the enclosure.

[0007] It should be noted that the granular material fill height of the enclosure, which corresponds to the granular material level of the enclosure, refers to the fact that the fill height, in the enclosure's operating configuration—that is, in the horizontal position of the enclosure's longitudinal axis—is defined relative to a horizontal reference plane. This horizontal reference plane is the plane passing through the lowest point of the cylindrical wall of The enclosure is in its operating configuration. This level is taken in the leveled state of the granular material, that is, in a state where the top surface of the granular material is substantially flat. This leveling of the granular material, distributed homogeneously within the enclosure, can be achieved by simply rotating the enclosure. It should be noted that the volume of granular material corresponding to this height or filling level can be determined empirically or by calculation. In practice, for example, when a is equal to zero, and the filling height is equal to the inner radius of the cylindrical enclosure, the volume of granular material in the enclosure used to form the moving bed is equal to half the volume of the enclosure minus half the volume of the tube. The tube is a fixed tube, that is, stationary when the enclosure is rotating. This tube is therefore not rotationally fixed to the enclosure.The coaxial arrangement of the fluid receiving tube, aligned with the chamber's axis of rotation, creates a consistent and dense flow of granular material particles around the tube, combined with a predefined chamber fill level. This optimizes heat transfer between the granular material and the fluid. This design ensures near-constant contact between the tube and at least some of the granular material during chamber rotation. Specifically, it allows the granular material to circulate over both the upper and lower sections of the fluid receiving tube as the chamber rotates. This "dual-flow" regime of granular material results in optimized convection at the surface of the fluid receiving tube, which in turn enhances heat transfer.The coaxial arrangement of the tube inside the enclosure also allows for a continuous fluid supply to the tube, in parallel with the rotation of the enclosure. Naturally, the enclosure is closed when full, before rotation begins.

[0008] According to one implementation method of the process, the rotation of said enclosure around an axis coinciding with the longitudinal axis of the enclosure is carried out at an angular speed between 5 and 50 rpm.

[0009] According to one implementation of the process, the cylindrical enclosure, which is delimited by a cylindrical wall and two end faces, is, for its filling with granular material and / or emptying it, provided with at least one closable opening in the cylindrical wall of said enclosure.

[0010] Preferably, this opening extends from one end face to the other end face of the enclosure.

[0011] The invention further relates to a heat transfer installation between a granular material suitable for forming a moving bed and a fluid, said installation comprising a cylindrical enclosure having an operating configuration in which the longitudinal axis of the enclosure extends horizontally and in which said enclosure is suitable for being filled with a volume of granular material corresponding to the moving bed to be formed, at least one cylindrical fluid receiving tube disposed at least partially inside the enclosure and a drive system for rotating the enclosure around an axis coinciding with the longitudinal axis of the enclosure, characterized in that the fluid receiving tube is a fixed tube which is disposed coaxially with the longitudinal axis of rotation of the enclosure and which opens, at each of its ends, to the outside of the enclosure in order to be able to be connected to a fluid circulation circuit,and in that the volume of granular material in the cylindrical enclosure used to form the moving bed corresponds to a granular material filling height of the enclosure, within the range of heights defined by the formula, R + ax R1, where R corresponds to the inner radius of the cylindrical chamber and R1 to the inner radius of the cylindrical fluid receiving tube, and a is between 0 and 1, this filling height corresponds to the level of granular material in the chamber when the granular material is leveled and homogeneously distributed within the chamber. This installation is suitable for implementing the process described above. Again, the coaxial arrangement of the fluid receiving tube to the longitudinal axis of rotation of the chamber, combined with a predefined filling level of the chamber, creates a regular and dense flow of the constituent particles of the granular material around the fluid receiving tube, thus optimizing heat transfer between the granular material and the fluid.This design allows for almost constant contact between the tube and at least part of the granular material during the rotation of the enclosure. In particular, this design allows for the circulation of the granular material flow over the entire area. upper and lower parts of the fluid receiving tube during the rotation of the chamber. Thanks to this regime, called the "bi-flow" regime of the granular material flow, there is an optimization of convection at the surface of the fluid receiving tube, this optimization being favorable to heat transfer.

[0012] According to one embodiment of the invention, the ratio of the inner radius of the enclosure to the inner radius of the tube is between 3 and 15.

[0013] According to one embodiment of the invention, the cylindrical enclosure, which is delimited by a cylindrical wall and two end faces, is provided, for its filling with granular material and / or its emptying, with at least one closable opening formed in the cylindrical wall of said enclosure. The filling of the enclosure can be carried out homogeneously along its entire length. Leveling can be achieved by simply rotating the enclosure. Preferably, this opening extends from one end face to the other end face of the enclosure.

[0014] According to one embodiment of the invention, said installation comprises at least one chamber filling station, said station comprising at least one hopper positioned above the chamber in the chamber's operating configuration, this hopper being mounted to move along an axis parallel to the chamber's longitudinal axis of rotation. Again, this arrangement allows for homogeneous filling of the chamber.

[0015] According to one embodiment of the invention, the installation includes a collector for the granular material contained within the enclosure, this collector being positioned beneath the enclosure, vertically aligned with the opening in the cylindrical wall of the enclosure. This results in easy emptying of the enclosure.

[0016] According to one embodiment of the invention, the enclosure's rotation drive system is configured to rotate the enclosure at an angular speed between 5 and 50 rpm.

[0017] According to one embodiment of the invention, the enclosure's rotation drive system comprises at least one rotating member meshed with an external part of the enclosure.

[0018] According to one embodiment of the invention, the fluid is a liquid, preferably water. Brief description of the drawings

[0019] The invention will be better understood upon reading the following description of exemplary embodiments, with reference to the attached drawings in which:

[0020] [Fig. 1] represents a schematic view of a heat transfer installation according to the invention;

[0021] [Fig. 2] represents a cross-sectional view of the enclosure to illustrate the range of filling heights of the enclosure;

[0022] [Fig. 3] represents a cross-sectional view of the enclosure in the rotating state to illustrate a "bi-fluid" regime;

[0023] [Fig. 4] represents a partial perspective view of a heat transfer installation during the granular material filling phase of the enclosure;

[0024] [Fig. 5] represents a partial perspective view of a heat transfer installation during the granular material emptying phase of the enclosure.

[0025] As mentioned above, the invention relates to a heat transfer process between a granular material 14 suitable for forming a moving bed and a fluid, and the installation 1 in particular for the implementation of such a process.

[0026] The granular material 14 can be of any nature and originate from the chemical, pharmaceutical, food, or other industries. Figure 2 illustrates an example of granular material 14 made of glass beads. Ideally, the particle size of the granular material 14 is between 500 microns and 1 cm. The fluid 15 is a liquid, preferably water. Water has good thermal storage properties and is inexpensive.

[0027] Installation 1, as illustrated in Figure 1, comprises a cylindrical enclosure 2 delimited by a cylindrical wall 6 and two end faces 7, each formed here by a centrally hollowed flange. This cylindrical enclosure 2 has a longitudinal axis XX' formed by the longitudinal axis of the cylinder. In the operating configuration, the longitudinal axis XX' of the enclosure 2 extends horizontally, as illustrated in particular in figure 1.

[0028] Installation 1 further includes a cylindrical fluid receiving tube 3. This cylindrical tube 3 is disposed at least partially inside the enclosure 2 coaxially with the longitudinal axis XX' of the enclosure 2. This cylindrical tube 3 opens at each of its ends either outside the enclosure 2 or projecting from said end face. The opening of each end of the tube 3 is disposed at the level of an end face 7 of the enclosure 2 or projecting from said end face. This cylindrical tube 3 is, at each of its ends, connected to a fluid circulation circuit 5 to allow fluid to be received inside the tube 3 and for the circulation of said fluid inside the tube 3. For this purpose, the fluid circulation circuit 5 may be equipped with a pump, as illustrated in Figure 1.A rotating fitting can be provided between the tube and each end face 7 of the enclosure so that the tube 3 does not rotate and only the enclosure rotates around the tube 3. The tube 3 remains fixed.

[0029] Indeed, installation 1 also includes a system 4 for rotating the enclosure 2 around an axis coinciding with the longitudinal axis XX' of the enclosure 2. Thus, the fluid receiving tube 3 is also coaxial with the axis of rotation of the enclosure 2. This system 4 for rotating the enclosure 2 includes at least one rotating element 11 meshing with an external part of the enclosure 2. This rotating element 11 is in the form of a pinion located outside the enclosure 2, beneath the enclosure 2. This rotating element 11 meshes with a notch on an end face of the enclosure, the flange of which is in the form of a ring circumferentially fitted with teeth. These teeth close the notch in contact with the teeth of the pinion.

[0030] The drive system 4 further includes at least one electric motor 12 in contact with the rotating member 11 for the rotational drive of said rotating member 11 around an axis parallel to the longitudinal axis XX' of rotation of the enclosure 2 and a control unit 13 for the electric motor(s) 12.

[0031] In the example shown, a drive system 4 is provided with two motor / rotating component assemblies 11, namely one assembly per end face 7 of the enclosure 2, said assemblies operating synchronously. Alternatively, a single assembly may be provided.

[0032] The rotation drive system 4 for chamber 2 is configured to rotate chamber 2 at an angular speed between 5 and 50 revolutions per minute. Chamber 2 is intended to be filled with a volume of granular material 14 corresponding to a granular material filling height H of chamber 2. This granular material filling height H of chamber 2 is measured from a horizontal plane passing through the lowest point of the cylindrical wall of the chamber, in the chamber's operating configuration. This height H corresponds to the filling level of the chamber with granular material. This height H is therefore measured when the granular material is level and homogeneously distributed within chamber 2, as illustrated in Figure 2.This height H falls within the height range defined by the formula R + ax R1, where R corresponds to the inner radius of the cylindrical enclosure and R1 to the inner radius of the cylindrical fluid receiving tube 3, and a is between 0 and 1. It should be noted that a can be an integer or a decimal. The expression "a is between 0 and 1" also includes the values ​​0 and 1.

[0033] In other words, the fill height (or fill level) of enclosure 2 is between H1 and H2 with H1 being equal to R and H2 being equal to R + R1.

[0034] Therefore, to obtain a "dual-flow" system, the height H is between R and R+R1. The volume of granular material corresponding to this filling height can be determined by calculation when the dimensions of the enclosure 2 and the tube 3, as well as the dimensional characteristics of the granular material 14, are known, but also empirically, for example, by observing the filling. The inventors found that outside this range of filling heights, the system is "single-flow," meaning that the flow of granular material is localized to the upper or lower part of the tube, so that heat transfer is not optimized.

[0035] In the example shown, enclosure 2 has a diameter of 40 cm. The cylindrical fluid receiving tube 3 has a diameter of 10 cm. Ideally, the ratio of the inside radius of enclosure 2 to the inside radius of tube 3 is between 3 and 15.

[0036] To allow the filling and emptying of the enclosure 2 with granular material 14, the cylindrical enclosure 2 is provided with at least one closable opening 8 in the cylindrical wall 6 of said enclosure 2. This opening 8 preferably extends from one end face 7 to the other end face 7 of the enclosure 2.

[0037] The closing mechanism for this opening 8 may be formed by a movable part of the cylindrical peripheral wall 6 of the enclosure 2. This movable part may be in the form of at least one shutter or door closing said opening in the closed position. The transition from the closed to the open position of the opening may be achieved by sliding and / or pivoting and / or dismantling said movable part.

[0038] Installation 1 also includes a filling station for enclosure 2. This station includes at least one hopper 9 positioned above enclosure 2 in the configuration for use of enclosure 2. This hopper 9 is mounted movable along an axis parallel to the longitudinal axis XX' of rotation of enclosure 2, as illustrated in Figure 4.

[0039] The installation also includes a collector 10 for the granular material 14 contained in the enclosure 2. This collector 10 is arranged under the enclosure 2 vertically above the opening 8 in the cylindrical wall 6 of the enclosure 2, as illustrated in Figure 5.

[0040] In practice, chamber 2 is in its operating configuration, that is, with its longitudinal axis XX' extending horizontally. The opening 8 of the chamber is therefore positioned upwards for filling chamber 2 with granular material 14, and the hopper 9 is moved parallel to the longitudinal axis XX', which forms the axis of rotation of chamber 2, to ensure homogeneous filling of chamber 2, i.e., along its entire length. Leveling can then be carried out by simply rotating chamber 2 to verify that the filling level or height conforms to the desired level. This filling thus occurs along the entire length of chamber 2 thanks to the movement of the hopper 9, as illustrated in Figure 4. Once the filling height H is reached, the opening 8 of the chamber is closed. During this filling, fluid 15 can also be brought into the fluid receiving tube 3.Once chamber 2 has been filled and chamber 2 closed, chamber 2 can be. Driven in rotation, fluid 15 can circulate in the fluid receiving tube 3 under the action of the pump equipping the fluid circulation circuit 5. Heat transfer in a "two-flow" regime can occur between the granular material and the fluid. The temperature of the granular material 14 and / or the fluid 15 can be controlled. The rotation of the chamber 2 can be stopped, for example, when the temperature difference between the temperature of the granular material and the temperature of the fluid is less than a predetermined value.

[0041] Due to the relative positioning of tube 3 within chamber 2 and the fill level of chamber 2, heat transfer is optimal, as illustrated in Figure 3, since heat transfer can occur continuously on both the upper and lower parts of tube 3 during the rotation of the chamber. 2. Once heat transfer is complete, the rotation of chamber 2 is stopped and the chamber 2 is emptied, as illustrated in Figure 5. For this purpose, the opening 8 of chamber 2 is oriented downwards and opened. The contents of chamber 2 flow into the collector 10, which is a container with an open top. This container is positioned below chamber 2, directly above the opening 8 in the cylindrical wall of chamber 2.A new filling of chamber 2, as described above, can then be considered for the implementation of a new heat transfer operation between a bulk granular material and the fluid 15. Each heat transfer operation comprises filling chamber 2 with said granular material while it is in its operating configuration, supplying the chamber with fluid via the cylindrical fluid receiving tube 3 located at least partially inside chamber 2, and rotating chamber 2 around its longitudinal axis XX'. This rotation occurs in parallel with the circulation of the fluid inside the fluid receiving tube 3.

Claims

Claims

1. Method of heat transfer between a granular material (14) capable of forming a moving bed and a fluid (15), said method comprising: in a so-called use configuration of a cylindrical enclosure (2) in which the longitudinal axis (XX') of said enclosure (2) extends horizontally - filling said enclosure (2) with a volume of granular material (14) corresponding to the moving bed to be formed, - a fluid supply to said enclosure (2) via at least one cylindrical fluid receiving tube (3) arranged at least partially inside the enclosure (2) and - a rotational drive of said enclosure (2) around an axis coinciding with the longitudinal axis (XX') of the enclosure, characterized in that the cylindrical fluid receiving tube (3) is a fixed tube (3) coaxial with the longitudinal axis (XX') of rotation of the enclosure (2) which opens, at each of its ends, outside the enclosure (2) so as to be able to be connected to a fluid circulation circuit (5) and in that the volume of granular material (14) of the cylindrical enclosure (2) used for the formation of the moving bed corresponds to a filling height (H) of granular material of the enclosure (2) included within the range of heights defined by the formula: R + ax R1 with R corresponding to the inner radius of the cylindrical enclosure (2) and R1 to the inner radius of the cylindrical fluid receiving tube (3) and a being between 0 and 1, this filling height (H) corresponding to the level of granular material (14) of the enclosure (2) in the leveled state of the granular material (14) distributed homogeneously in the enclosure (2).

2. Heat transfer method according to claim 1, characterized in that the rotational drive of said enclosure (2) around an axis coincident with the longitudinal axis (XX') of the enclosure (2) takes place at an angular speed of between 5 and 50 rpm.

3. Heat transfer method according to one of claims 1 or 2, characterized in that the cylindrical enclosure (2), which is delimited by a cylindrical wall (6) and two end faces (7), is, for its filling with granular material (14) and / or its emptying, provided with at least one closable opening (8) made in the cylindrical wall (6) of said enclosure (2).

4. Heat transfer method according to claim 3, characterized in that the closable opening (8) provided in the cylindrical wall (6) of the enclosure (2) extends from one end face (7) to the other end face (7) of the enclosure (2).

5. Installation (1) for heat transfer between a granular material (14) capable of forming a moving bed and a fluid (15), said installation (1) comprising a cylindrical enclosure (2) having a configuration of use in which the longitudinal axis (XX') of the enclosure (2) extends horizontally and in which said enclosure (2) is capable of being filled with a volume of granular material (14) corresponding to the moving bed to be formed, at least one cylindrical tube (3) for receiving fluid arranged at least partially inside the enclosure (2) and a system (4) for driving the enclosure (2) in rotation about an axis coinciding with the longitudinal axis (XX') of the enclosure (2), characterized in that the fluid receiving tube (3) is a fixed tube (3) which is arranged coaxial with the longitudinal axis (XX') of rotation of the enclosure (2) and which opens, at each of its ends,outside the enclosure (2) so as to be able to be connected to a fluid circulation circuit (5), and in that the volume of granular material (14) of the cylindrical enclosure (2) used for forming the moving bed corresponds to a filling height (H) of granular material (14) of the enclosure (2), included within the range of heights defined by the formula R + ax R1 with R corresponding to the internal radius of the cylindrical enclosure (2) and R1 to the internal radius of the cylindrical fluid receiving tube (3) and a being between 0 and 1 this filling height (H) corresponding to the level of granular material (14) of the enclosure (2) in the leveled state of the granular material (14) distributed homogeneously in the enclosure (2).,

6. Heat transfer installation (1) according to claim 5, characterized in that the ratio of the inner radius (R) of the enclosure (2) to the inner radius (R1) of the tube (3) is between 3 and 15.

7. Heat transfer installation (1) according to one of claims 5 or 6, characterized in that the cylindrical enclosure (2), which is delimited by a cylindrical wall (6) and two end faces (7), is, for its filling with granular material (14) and / or its emptying, provided with at least one closable opening (8) formed in the cylindrical wall (6) of said enclosure (2)

8. Heat transfer installation (1) according to claim 7, characterized in that the opening (8) extends from one end face (7) to the other end face (7) of the enclosure (2).

9. Heat transfer installation (1) according to one of claims 5 to 8, characterized in that said installation (1) comprises at least one station for filling the enclosure (2), said station comprising at least one hopper (9) positioned above the enclosure (2) in the configuration for use of the enclosure (2), this hopper (9) being mounted to move along an axis parallel to the longitudinal axis (XX') of rotation of the enclosure (2).

10. Heat transfer installation (1) according to one of claims 7 or 8, characterized in that the installation comprises a collector (10) of the granular material (14) contained in the enclosure (2), this collector (10) being arranged under the enclosure (2) vertically above the opening (8) made in the cylindrical wall (6) of the enclosure (2).

11. Heat transfer installation (1) according to one of claims 5 to 10, characterized in that the system (4) for driving the enclosure (2) in rotation is configured to drive the enclosure (2) in rotation at an angular speed of between 5 and 50 rpm.

12. Heat transfer installation (1) according to one of claims 5 to 11, characterized in that the system (4) for driving the enclosure (2) in rotation comprises at least one rotating member (11) engaged by meshing with an external part of the enclosure (2).

13. Heat transfer installation (1) according to one of claims 5 to 12, characterized in that the fluid (15) is a liquid, preferably water.

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