Electric Fluid Flow Heater with Heating Element Support Member

Abstract

An electric heater to heat a flow of a fluid having a jacket block comprising a plurality of longitudinal bores to allow the through-flow of a gas phase medium. An elongate heating element extends through each of the bores and is positionally stabilised relative to the jacket block via at least one support member, optionally in the form or an elongate rod to inhibit undesirable independent axial and/or lateral movement of the heating element relative to the jacket block.

Claims

1. An electric heater to heat a flow of a fluid, comprising: at least one axially elongate jacket element defining an axially elongate jacket block having first and second lengthwise ends; a plurality of longitudinal bores or channels extending internally through the jacket block and being open at each of the respective first and second lengthwise ends; at least one heating element extending axially through the bores or channels and having respective bent axial end sections such that the at least one heating element emerges from and returns into adjacent or neighbouring bores or channels at one or both the respective first and second lengthwise ends, the at least one heating element and the jacket block forming a heating assembly; and a casing positioned to at least partially surround the heating assembly, wherein at least one support member is connected to or projecting from the casing to contact at least some of the bent axial end sections and inhibit axial and/or lateral movement of the at least one heating element relative to the jacket block and/or the casing.

2. The electric heater as claimed in claim 1, wherein the at least one support member comprises at least one rod extending between the bent axial end sections and the first lengthwise end of the jacket block.

3. The electric heater as claimed in claim 2, comprising a plurality of rods, each rod extending respectively between each of a plurality of bent axial end sections and the first lengthwise end.

4. The electric heater as claimed in claim 2, wherein the at least one rod is positioned in contact or near-touching contact with the least one heating element at respective inner regions of the bent axial end sections.

5. The electric heater as claimed in claim 3, wherein the plurality of bent axial end sections are positioned adjacent one another and are aligned in a row and a respective rod of the plurality of rods extends through the bent axial end sections of the row.

6. The electric heater as claimed in claim 2, wherein each of the rods comprise recesses to at least partially receive a portion of the at least one heating element at each of the respective bent axial end sections.

7. The electric heater as claimed in claim 1, wherein the support member comprises a generally circular, polygonal or rectangular cross sectional profile.

8. The electric heater as claimed in claim 1, wherein the heating element is bent through 170 to 190, 175 to 185 or generally 180 at the bent axial end sections.

9. The electric heater as claimed in claim 1, wherein the support member comprises a non-electrically conducting material.

10. The electric heater as claimed in claim 9, wherein the non-electrically conducting material is formed as a coating at the support member.

11. The electric heater as claimed in claim 10, wherein the support member comprises a metallic core and the non-electrically conducting material is formed as a coating to at least partially surround the metallic core.

12. The electric heater as claimed in claim 1, wherein the at least one jacket element comprises a non-electrically conducting material.

13. The electric heater as claimed in claim 1, wherein the casing comprises an outer sheath and a plurality of spacers extending radially between the outer sheath and the jacket block.

14. The electric heater as claimed in claim 13, wherein each of the spacers comprises a part-disc shaped member having a central aperture through which a part of the jacket block extends.

15. The electric heater as claimed in claim 13, further comprising a bracket provided at the spacer at or towards the first lengthwise end of the jacket block, the support member extending between the bracket and the bent axial end sections.

16. The electric heater as claimed in claim 15, comprising at least a pair of the brackets provided at the spacer at or towards the first lengthwise end of the jacket block and wherein the support member comprises at least one rod extending from the brackets and through the bent axial end sections.

17. The electric heater as claimed in claim 16, wherein the rod extends generally perpendicular to the elongate bores or channels.

18. The electric heater as claimed in claim 13, comprising a plurality of the jacket elements assembled together as a unitary body and at least partially surrounded by the spacers.

19. The electric heater as claimed in claim 18, wherein the outer sheath comprises a generally hollow cylindrical or hollow cuboidal shape encapsulating the heating assembly.

20. The electric heater as claimed in claim 19, wherein the spacers are attached to a radially inner surface of the sheath.

21. The electric heater as claimed in claim 11, wherein each of the jacket elements comprise a projection at a first region and a groove at a second region at at least one external surface, the projection of one of the jacket elements configured to at least partially sit within the groove of an adjacent jacket element to at least partially interlock the jacket elements.

22. The electric heater as claimed in claim 1, wherein: the at least one jacket element comprises a plurality of jacket elements assembled together to form the elongate jacket block; the at least one support member comprises a plurality of rods and the bent axial end sections are positioned adjacent one another and are aligned into rows such that a respective rod of the plurality of rods extends through the bent axial end sections of each respective row; the casing comprises an outer sheath and the heater further comprises a plurality of spacers extending radially between the outer sheath and the jacket block, the spacers comprising central apertures through which a part of the jacket block extends; and the heater further comprising a plurality of brackets provided at one of the spacers at or towards the first lengthwise end of the jacket block such that the rods extend between the brackets and through the bent axial end sections of each row.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0041] A specific implementation of the present invention will now be described, by way of example only, and with reference to the accompanying drawings in which:

[0042] FIG. 1 is a cross sectional side view of an electric heater according to one aspect of the present invention;

[0043] FIG. 2 is a perspective view of a heating assembly forming a part of the electric heater of FIG. 1;

[0044] FIG. 3 is a further perspective view of a first lengthwise end of the heating assembly of FIG. 2;

[0045] FIG. 4 is a further perspective view of the first lengthwise end of the heating assembly of FIG. 3; and

[0046] FIG. 5 is a perspective view of neighbouring and adjacent jacket elements forming a part of the heating assembly of FIG. 4.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT OF THE INVENTION

[0047] Referring to FIGS. 1, 2 and 3 an electric heater 1 comprises a casing 2 in a form of a cylindrical sheath 3 (having internal and external facing surfaces 3b, 3a respectively) that defines an internal chamber 4 open at both axial ends. A heating assembly indicated generally by reference 5 is mounted within chamber 4. Heating assembly 5 is formed from a plurality of lengthwise elongate jacket elements 6 assembled and held together to form a lengthwise elongate jacket block 7. Each elongate jacket element 6 comprises a lengthwise extending longitudinal internal bore 8 extending the full length of each jacket element 6 so as to be open at a first and second axial end 7a, 7b of the jacket block 7. The jacket element 6 and jacket block 7 are formed as hollow bodies in which the solid mass and volume extends continuously between the first and second axial ends 7a, 7b. That is, the jacket elements 6 and jacket blocks 7 are not discontinuous between respective ends 7a, 7b. Such an arrangement is advantageous to maximise the extent and efficiency of thermal energy transfer within the respective jacket elements 6 as explained in further detail herein.

[0048] Jacket block 7 is mounted in position (within casing 2) via a pair of disc-shaped spacers 9a, 9b positioned in a lengthwise direction towards each jacket block axial end 7a, 7b. Sheath 3 and spacers 9a, 9b may be formed from metal such that spacers 9a, 9b are secured to an internal facing surface 3b of sheath 3 via welding. Each spacer 9a, 9b comprises a central aperture 10 having a rectangular shape profile and dimensioned to accommodate jacket block 7 that also comprises an external generally cuboidal shape profile. Accordingly, jacket block 7 is mounted within each spacer aperture 10 so as to be suspended within chamber 4 and spatially separated from sleeve internal facing surface 3b.

[0049] A heating element indicated generally by reference 11 is formed as an elongate rod having respective ends 11d, 11e projecting generally from one of the axial ends of jacket block 7. Ends 11d, 11e are illustrated in FIGS. 1 to 3 projecting from the hot end 7b of the jacket block 7 for illustrative purposes. Ends 11d, 11e, preferably extend from the cool end 7a of jacket block 7. Heating element 11 comprises a generally circular cross sectional profile and is dimensioned slightly smaller than the cross-sectional area of each jacket element bore 8. The single heating element 11 is adapted to extend sequentially through each elongate bore 8 of the jacket block 7 via respective bent axial end sections 11a and 11b. In particular, heating element 11 emerges from one bore 8 of a first jacket element 6 is bent through 180 (heating element end section 11a) so as to return into an adjacent or neighbouring bore 8 at the jacket block first axial end 7a. This is repeated at the jacket block second axial end 7b via bent end sections 11b. Heating element ends 11d, 11e are capable of being coupled to electrical connections to enable a current to be passed through element 11 as will be appreciated.

[0050] Referring to FIG. 5, each jacket element 6 comprises four longitudinal extending side faces 6a, 6b, 6e and 6h that are generally planar such that each jacket element comprises an external generally square cross sectional shape profile adapted to enable the jacket elements to sit together in touching contact to form a rectangular cuboidal unitary body in which the individual side faces of the jacket elements 6 form the external facing surfaces of the jacket block 7. A small gap is provided between each spacer aperture 10 and the external surfaces of jacket block 7 (defined by jacket element side faces 6a, 6b, 6e, 6h). Such gaps accommodated differential thermal expansion of the spacers 9a, 9b (typically formed from metal) and the jacket elements 6 that are preferably formed from a non-electrically conducting refractory material. However, at least some structural support of the jacket block 7 and heating element 11 is provided by spacers 9a, 9b (via apertures 10) that are at least partially in contact with jacket block 7. To inhibit axial and lateral movement of each of the individual jacket elements 6 (relative to a longitudinal axis 12 extending through heater 1), each jacket element 6 comprises a groove 6f and a corresponding rib 6g extending laterally across jacket elements 6 and perpendicular to axis 12. The grooves 6f and ribs 6g of neighbouring jacket elements 6 are adapted to inter-fit one another to provide a part-tessellating jacket block 7 resistant to axial loading forces and lateral shear forces. The groove and rib arrangement (6f, 6g) of FIG. 5 is complementary to the positional holding of the heating assembly 5 via spacers 9a, 9b.

[0051] The present electric heater is specifically configured with at least one support member 13 (alternatively termed a heating element stabilisation unit) configured to positionally stabilise the heating element 11 relative to the jacket block 7, spacers 9a, 9b and/or casing 2 (encompassing sheath 3). Such an arrangement is advantageous to minimise independent movement of the heating element 11 with respect to the jacket block 7 and specifically the jacket block axial ends 7a, 7b. As will be appreciated, the dimensions of the heating element 11 and bores 8 are carefully controlled to achieve a desired small separation gap between the inward facing surface of each bore 8 and the external surface of heating element 11. Such an arrangement is advantageous to maximise the effectiveness and efficiency of heat energy transfer from element 11 to a gas phase medium initially introduced into the chamber 4 at position 14a to then flow through each of the bore 8 and exit from the heating assembly 5 at position 14b. This effectiveness and efficiency of heat energy transfer is also provided, in turn, by the heating elements 6 extending continuously lengthwise (axially) between respective ends 7a, 7b. In particular, heating element 11 is entirely and continuously housed, covered and contained by the elongate jacket elements 6 between ends 7a, 7b. When the electric heater 1 is suspended vertically in use, undesirable contact between the bent end sections 11a, 11b and the end faces 6c, and in particular the annular edges that define the entry and exit end of each bore 8, contribute to fatigue and damage to the heating element 11 and a corresponding reduction in the service lifetime of the heater 1. To mitigate this, the heating element support member 13 is specifically provided to inhibit and in particular prevent any axial and lateral movement of the heating element 11 (independently of jacket block 7). Advantageously, the support member 13 is positioned at a cool axial end of the heating assembly 5 corresponding to the gas inflow 14a in contrast to a hot axial end for heated gas outflow (position 14b). The cool first axial end 7a is the region of lower stress (lower temperature differential) relative to the second axial end 7b and therefore stabilisation at the first axial end 7a is more practical and effective. The support member 13 comprises a pair of spaced apart brackets 15 that are secured to a front face 16 of spacer 9a so as to project forwardly into the oncoming gas flow 14a. Each bracket 15 projects beyond the axial end face 6c of the jacket block 7. Boreholes 17 extend through each bracket 15 along axis 19 extending perpendicular to main longitudinal axis 12 of the heater 1. An elongate rod (or bar) 18 is mounted within each borehole 17 to be centred on axis 19 and to extend between each of the opposed brackets 15 and laterally across the end face 6c of the jacket block 7. The present invention comprises a plurality of stabilisation rods 18 each extending parallel to one another and perpendicular to the main longitudinal axis 12. As illustrated in FIGS. 1, 2 and 4, the bent axial sections 11a are arranged in rows at each end face 6c so as to accommodate a single respective rod 18 that is inserted and passes through and under each of the bent sections 11a so as to be positioned or at least partially entrapped between the bent (or looped) end sections 11a and the collective end face 6c of the jacket block 7. In such a configuration, the heating element 11 is prevented from movement in the gas flow direction (from position 14a to 14b along axis 12) due to contact with the rod 18 which is held securely in fixed position via brackets 15.

[0052] Referring to FIG. 4, each rod 18 comprises a plurality of recesses 18a that are space apart along the length of rod 18 to correspond to the region of contact (or near contact) with each bent end section 11a. Each recess 18a is curved and complementary to the curved profile of the heating element at a radially inner region 11c at each bent end section 11a. That is, each heating element in each region 11c is at least partially accommodated within each respective recess 18a. Such an arrangement is advantageous to provide (or increase) lateral stabilisation of heating element 11 (in a direction perpendicular to longitudinal axis 12).

[0053] The present electric heater having an axially and laterally stabilised heating element 11 is configured with an extended operation lifetime via minimised independent movement of the heating element 11 relative to the heating assembly 5 and in particular jacket block 7.

[0054] As will be appreciated, whilst the subject invention is described with reference to elongate rods 13 inserted through each bent end section 11a, the same stabilisation may be achieved via alternative components and arrangements in which the bent end sections 11a are contacted by an abutment component that is secured, either directly or indirectly to casing 2 (for example via intermediate brackets 15 and/or spacers 9a, 9b). For example, such abutment components may comprise eyelets, hook shaped members, plates or washers adapted to at least partially sit between the radially inner region 11c of each end section 11a and the end face 6c of jacket block 7.