GB2241138A

GB2241138A - Electrical heating apparatus

Info

Publication number: GB2241138A
Application number: GB9103141A
Authority: GB
Inventors: Helmut Meyer
Original assignee: Draack & Meyer Polytetra
Current assignee: Draack & Meyer Polytetra
Priority date: 1990-02-16
Filing date: 1991-02-14
Publication date: 1991-08-21
Anticipated expiration: 2011-02-14
Also published as: CH681340A5; FR2658693A1; FR2658693B1; DE4100008A1; JPH0660970A; DE9001852U1; GB2241138B; GB9103141D0; DE4100008C2

Description

2:2 _el X X 3 =5 f 1 Electrical Heating Apparatus The present invention

relates to an electrical heating apparatus and more particularly an electrical heating apparatus for a corrosive fluid medium.

In situations which involve a requirement for heating an aggressive or corrosive f luid medium, use may be made of an electrical heating apparatus comprising at least one bar-like heating body which comprises a sheathing of a fluoroplastic-based material, with the ends of the heating body being brought together in a connecting head. Typically, the connecting unit is in the form of a housing which can be closed by a cover fitted thereto. The configuration of such a known connecting head is such that under no circumstances can it come into contact with the medium to be heated for-a prolonged period of time, for example by virtue of being immersed therein.

According to the present invention there is provided an electrical heating apparatus for a corrosive fluid comprising at least one bar-like heating body including a sheathed conductor, and a connecting head comprising a body including receiving passages into which the ends of the heating body are sealed, and a further passage in which a sheathed connecting line is sealed in electrical contact with the conductor, whereby the apparatus is resistant to immersion in the corrosive fluid.

In a preferred arrangement all or part of the apparatus is protected by a layer of plastics material, preferably a fluoroplastic. The heating bar 2 l- and the conecting line are non-rotatably mounted in the connecting head.

As will become more clearly apparent from the following description of a. preferred embodiment, an electrical heating apparatus according to the invention is of such a configuration that it can now be dipped into a corrosive or attacking fluid medium to any depth as both the connecting head and the connecting line are designed to be resistant to

3 the medium in question and the apparatus enjoys good sealing integrity. Preferably the 'ends. of the heating body have material injected therearound or have welding therearound to seal it in relation to the connecing head. The connecting line may similarly have material injected therearound or welding:therearound.

In a preferred feature of the invention, the bar-like heating body way be in the form of a tubular heating body, and the ends thereof way be of a non-round configuration, while the passages are designed to receive the non-round configuration of the ends of the heating body.

The non-round configuration way be pro vided for example by means of a separate portion which is fitted on to the end portions of the heating body. That fixing arrangement can provide at the same time for an electrical connection between the protective conductor of the connecting line and a metal jacket of the tubular heating body. That has the advantage that that connection can be produced in an electrically secure fashion, in a simple manner.

In accordance with a further preferred feature of the invention, the heating body has portions of a curved configuration, while in the portions of curved configuration the output in relation to surface area is reduced in coison with portions of the heating body which are of an at least substantially straight configuration. The reduction in heating output, in this context, my also include a reduction to zero. That ensures that the curved portions of the heating body do not suffer frcrn overheating at endangered locations thereof, for example in the internal radius of the curvature.

In a further preferred feature of the- invention, the heating body way be of a meander-like configuration and has straight portions arranged to extend in a conical configuration relative to each other. That provides that the inside radii of the curved portions are greater than in the case of straight portions which extend in parallel relationship with each other, without the structural width of the 1 4 heating body being increased overall. It is also possible for the conically extending configuration of the straight regions of the heating body to be combined with a reduced heating output in relation to surface area, in curved regions thereof.

A further preferred aiment of the invention can provide that the connecting head has fixng means which way be for example in the form of eye members or the like. That maker. it possible for exapple to combine a plurality of heating apparatuses together or to mount at least one protective or guard plate or support members, as well as fitting holding devices.

In another embodiment of the invention, the sheathing of the heating body may be of a multi-layer construction. In comparison with a single-layer construction, that arrangement provides an extra barrier layer which makes it more difficult for the surrounding medium to diffuse into the sheathing, or retards such diffusion effect, so that as a result the service life of the heating body is enhanced.

A further preferred feature of the invention my provide that the means for sealing the tubular heating body relative to the connecting head may be in the form of a screw seal, and the screw seal can be locked in position by a suitable securing means.

An apparatus according to the invention will now be described by way of example with reference to the accompanying drawings in which:

Figure 1 is a diagrammatic plan view of an electrical heating apparatus in accordance with the present invention, and Figure 2 is a partly sectional view on an enlarged scale of the connecting head of the Figure 1 beating apparatus, showing one of the ends of the heating body introduced into the connecting head, and the connecting line connected thereto.

Referring firstly to Figure 1, shown therein is an electrical heating apparatus identified generally by reference numeral 1 for heating an aggressive or corrosive fluid medium. The electrical heating J; X apparatus 1 comprises a bar-like heating body which is identified generally by reference numeral 2 and which is of a meander-like configuration.

The heating body 2 rises ends 3 and 4 which are brought together in a connecting head which is generally indicated by 5, where they are connected to a connecting feed line 6. The connecting head 5 is in the form of a solid body and is Made from a suitable plastics material, for example a fluoroplastic-based material. For accwTnodating the ends 3 and 4 of the heating body 2 and the connecting line 6, the connecting head 5 has passages which in Figure 2 are identified by reference numeral 7 for receiving the end 3 of the heating body 2, and which are shown in broken lines and identified by reference numeral 8 for receiving the end 4 of the heating body 2 and reference numeral 9 for receiving the connecting line 6.

As shown in Figure 2, the end 3 of the heating body 2 comprises an inner conductor 10 which is surrounded by an insulation 11 and a steel casing 12 which has a sheathing 13 of a fluoroplastic-base material. The sheathing 13 may also be pf a multi-layer construction.

The end 3 of the heating body 2, and in a corresponding fashion also the end 4 thereof, are introduced into the respective passages 7 and 8 in the connecting head 5, where they are electrically connected to the connecting line 6. For that purpose the connecting line 6 has a plurality of inner conductors, there being two inner conductors in the illustrated embodiment. One of the inner conductors of the connecting line is indicated at reference numeral 14 in Figure 2 and is introduced through the passage 9 and then passed into the passage 7. The conductor 14 is electrically connected to the inner conductor 10 of the heating body 2, for example by the pressed sleeve 15 shown in Figure 2. The inner conductor at the end 4 of the heating body is also connected to a further inner conductor of the connecting line 6 in a corresponding fashion. That region is provided with electrical insulation as indicated at 16 in Figure 2.

6 A protective conductor of the connecting line 6 is indicated by reference numeral 17 in Figure 2, more specifically the end"portion of the conductor 17 being expanded and passed on to the plain or smooth metal casing -12 at the end 3 of the heating body 2. The protective conductor is fixed -with a =rponent which is identified by reference numeral 18 and which serves on the one hand as a means for preventing rotary movement as between the end of the heating body 2 and the connecting head 5, whereby the ends of the heating body 2 are nonrotatably held in the body of the connecting head 5, and on the other hand serving to make an electrical connection between the protective conductor of the connecting line 6 and the rmtal casing of the tubular heating body 2. In order to ensure that the ends of the heating body are held non-rotatably in the connecting head 5, the member 18 is of a non- round configuration at its outside periphery. The passage in which the member 18 is received, being illustrated as the passage 7 in Figure 2, has a portion or recess of a corresponding non-round configuraton. Reference numeral 19 in Figure 2 identifies a seal while reference numeral 20 identifies a screw seal niaTd)er. The external screwthread of the screw seal member 20 and the corresponding internal screwthred in a recess for receiving same in the passage 7 are not shown for the sake of simplicity of the dreawing. The screw seal member 20 can be secured in position by a suitable securing means, illustrated in the form of at least one securing pin 23.

It will be appreciated that, instead of a screw sealing member, the ends 3, 4 of the heating body may be suitably accommodated in the connecting head 5 in sealed relationship therewith by mans of another form of seal, for example by material being injected therearound or welded therearound or produced by casting therearound. The connecting line 6 my also be sealed in relation to the connecting head 5 in the same or a similar manner to the sealing connections between the ends 3 and 4 of -the heating body 2 and the connecting head 5. Reference 4 k k 7 nun-erals 22 and 23 in Figure 2 identify screw sealing mrs for the end 4 of the heating body 2 and the connecting line 6, corresponding to the wr 20 described in greater detail hereinbefore.

The connecting head 5 additionally has fixing mans which arein the form of eyes in the illustrated embodb-ent, at 24.

As shown in Figure 1, the, heating body 2 is of a weander-like configuration, with straight portions 25 through 30 thereof being arranged to extend in a conical configuration relative to each other. That provides that the inside radius of the curved portions of the heating body is increased in cmiparison with a corresponding Manderlike configuration which involves the same overall width. The heating output of the heating body, in relation to surface area, way also be varied in respective portions thereof, in order to avoid overheating.

It will be appreciated that the above-described wbodiment has been set forth solely by way of example and that vario Vs other modifications and alterations my be made therein without thereby departing from the scope of the invention as defined by the appended clah-ns.

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Claims

1. An electrical heating apparatus f or use with a corrosive fluid comprising at 'least one bar-like heating body including a sheathed conductor, and a connecting head comprising a body including receiving passages into which the ends of the heating body are sealed, and a further passage in which a sheathed connecting line is sealed in electrical contact with the conductor, whereby the apparatus is resistant to immersion in the corrosive fluid.

2. An apparatus according to claim 1, wherein one or more of the following are formed from a plastics material:

(i) (ii) (iii) the conductor sheathing the connecting line sheathing at least part of the connecting head.

3. An apparatus according to claim 2, wherein the plastics material is a fluoroplastic.

4. An apparatus according to any preceding claim, wherein the ends of the heating body and/or the end of the connecting line are non-rotatably mounted in the connecting head.

5. Apparatus according to any preceding claim, wherein said ends of said heating body have material injected therearound to seal same in relation to said connecting head.

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6. Apparatus according to any preceding claim, wherein said ends of said heating body -have welding therearound to seal same in relation to said connecting head.

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7. Apparatus according to any preceding claim, wherein said connecting line has material injected therearound to seal same in relation to said connecting head.

8. Apparatus according to any preceding claim, wherein said connecting line has welding therearound to seal same in relation to said connecting head.

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9 Apparatus according to any one of the preceding claims wherein said heating body is a tubular heating body, the ends thereof have portions of a non-round -configuration, and the passages in said connecting head are adapted to receive the non-round portions at the ends of the heating body.

10. - Apparatus according to claim 9 wherein said non-round portion is in the form of a separate ccoponent fitted on to the corresponding end of said heating body, for simultaneously making an electrical connection between a protective conductor of the connecting line and a metal casing portion of the heating body.

11. Apparatus according to any one of the preceding claim wherein said heating body has portions of a curved configuration and in said portions of said curved configuration the output in relation to the surface area is reduced in comparison with portions of the heating body which are of an at least substantially straight configuration.

12. Apparatus according to any one of the preceding claims wherein the heating body is of a meander-like configuration- and has straight portions arranged to extend in a conical relationship relative to each other.

13. Apparatus according to any one of the preceding claims wherein the connecting head has fixing weans.

14- Apparatus according to any one of the preceding claims wherein the sheathing of the heating body is of a multi-layiar construction.

15. Apparatus according to any one of the preceding claim including weans for sealing said heating body and/or said connecting line 1.

11 relative to the connecting head, said sealing means being in the form of a screw seal ftE, and including securing mems for securing said screw seal mr in position.

16. - An electrical heating apparatus for a corrosive fluid medium comprising: a connecting head in the form of a solid body of material resistant to said medium and having first, second and third passages therein; at least one heating bar means having first and second ends, a sheathing of material resistant to said medium, and inner conductor manh therein, said first and second ends being accoated in said first and second passages and held non-rotatably therein in sealed relationship with said connecting head; and a connecting feed line accambodated in said third passage and held non-rotatably therein in sealed relationship with said connecting head, said connecting line including electrical conductor means electrically connected within said connecting head to said inner conductor ns of said heating bar mans and sald connecting line including insulation resistant to said medium.

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17 '.. Apparatus according to claim 16 wherein said sheathing of said heating bar mans is of a fluorosplastic-based material.

18. Apparatus according to claim 16 or claim 17. wherein said connecting head is of a fluoroplastic-based material.

19. - An electrical heating apparatus substantially as hereinbefore described with reference to the accaq:)anying drawings.

Published 1991 at Ite Patent Office. State House, 66171 High Holborn. London WC I R 47P. Further copies may be obtained from sake B. Unit 6. Nine Mile Point ewmfchnfach. Cross Keys. N. NPI 7HZ. Printed by Multiplex techniques lid. St Mary Cray. Kent.