WO2022089679A1

WO2022089679A1 - Electric heating sleeve

Info

Publication number: WO2022089679A1
Application number: PCT/DE2021/000173
Authority: WO
Inventors: Helmut Heinz
Original assignee: H. Heinz Messwiderstände GmbH
Priority date: 2020-10-28
Filing date: 2021-10-18
Publication date: 2022-05-05
Also published as: EP4237719A1; DE102020006614A1

Abstract

The invention relates to an electric heating sleeve for heating the valve spindle housing of valves used in high-temperature energy technology. The problem addressed by the invention is that of developing an electric heating sleeve for heating the valve spindle housing of valves used in high-temperature energy technology, which sleeve is resistant to the salts and acids used in high-temperature energy technology, and which ensures highly precise and very reliable temperature control over a long lifetime under very extreme conditions, such as high daily external temperature variations and extremely high air humidity, at a heating temperature of the heating sleeve of up to a maximum of 750°C. The electric heating sleeve (1) according to the invention, comprising two half-shells (3) which consist of cast material and have an inner contour (4) on the inside as a contact surface and an approximately cylindrical outer lateral surface (5) on the outside, is characterised inter alia in that the two half-shells (3) are completely identical in design, and a separate terminal box (7) for supplying energy is situated on each of the half-shells (3), and in that a spacer tube (9) is situated between the half-shell (3) and the terminal box (7) assigned thereto, and in that thermal insulation (14) that corresponds approximately in its thickness dimensions to the length of the spacer tube (9) is arranged around the outer lateral surface (5) of the half-shell (3).

Description

Electric heating sleeve

The invention relates to an electrical heating sleeve for heating the valve spindle housing of valves used in high-temperature energy technology, which are used in particular in connection with solar thermal power plants, mostly under very extreme conditions (such as in the desert), in order to use the superheated steam to operate the electrical to produce turbines.

During the course of the day's solar radiation, the brines are heated by solar cells. Temperatures of over 700°C occur here. These brines are pumped through the valves into appropriately insulated tanks and at night, when the outside temperatures drop, to generate superheated steam and then removed/drained/pumped back from the storage tanks through these valves to operate the turbines. The resulting rapid changes in temperature can result in a drop in temperature. At minus 27°C, the salts freeze and make the valves unusable, which is why the adjusting spindles are heated.

In the state of high-temperature energy technology, electric heaters for such valve spindle housings are known, which, as shown in Figure 1, consist of a tubular heating element wound around the respective valve spindle housing, which is additionally encased with an insulating material for thermal insulation (insulating material not shown in Figure 1 ).

confirmation copy] During assembly, as well as in the event of a defect for repairing it, the complete spindle head must be dismantled with this spindle heater constructed in this way, ie for the installation and replacement of the tubular heater.

In the prior art, despite the use of this electrical heating of the valve spindle housing, for example if the hot salts stored in liquid form at approx , at a valve temperature of, for example, approx. +27°C, the salts passed through the valve solidify in the valve body.

This inevitably means that the valve spindle can no longer be adjusted, i.e. that the valve is no longer functional.

The uncontrolled "frozen" valves then have to be completely removed and then repaired, which is very costly and time-consuming.

Special heating sleeves for heating tubular objects are already described in the prior art, particularly in the field of plastics processing.

For example, DE 34 28 539 A1 discloses a heating sleeve for heating tubular objects, in particular for injection nozzles of plastic injection molding machines, which consists of two bent metal plates, for example made of an aluminum alloy, and which correspond to the circumference of the respective tubular Object are bent and braced by means of a pipe clamp on the tubular object. It is essential that in the concavely curved inner surface of each of the plates there are grooves running parallel to the axis, into which, before the plates are bent, tubular heating elements in the form of heating cartridges are inserted.

However, this solution known from DE 34 28 539 A1 is by no means suitable for use in high-temperature energy technology, since this is not for rapid temperature changes over several 100°C are designed and they are not suitable for brine.

In addition, DE 4013538 A1 discloses another temperature control device for machines that process plastics, which is formed by two half-shells that are produced in a die-casting process, for example from aluminum. Temperature control elements are cast into these half-shells, which can be used as a heating element or as a cooling element, depending on requirements.

Due to the process, these temperature control elements have supporting surfaces which are not covered by the cast metal and which are directed towards both the inner and the outer lateral surface of the half-shell and which are required to secure the position of the temperature control element during injection molding.

These half-shells, which are produced according to the solution presented in DE 4013538 A1, are applied to the surface to be tempered and clamped using straps.

However, these aluminum half-shells produced according to DE 4013538 A1 cannot be used in high-temperature energy technology at heating temperatures of the heating jacket of up to 750 °C, since aluminum already becomes "soft" in the temperature range of 300 °C to 400 °C and already at approx 660° C melts.

In addition, there is a significantly increased tendency to corrosion in the area of the support surfaces at significantly lower temperatures, even under normal boundary conditions, which makes use under the extreme and saline conditions of high-temperature energy technology completely impossible.

Furthermore, DE 10 2010 021 968 A1 discloses a surface heating device, here for heating a container, which comprises at least one heat transfer body on which at least one heating element is arranged.

This heating element is a conductor that can be charged with electrical energy and has electrical insulation relative to the heat transfer body and which can also be bent non-destructively. In an advantageous embodiment of DE 10 2010 021 968 A1, the conductor is designed as a heating wire and the insulation is designed as a plastic sleeve lying against the heating wire.

This solution presented in DE 10 2010 021 968 A1 is also unsuitable for use in high-temperature energy technology, since the heating wire is encased in a plastic sheath and is therefore not suitable for temperatures of a maximum of 750°C.

It is therefore the object of the invention to develop an electrical heating sleeve for heating the valve spindle housing of valves used in high-temperature energy technology, which can be installed easily and quickly, but which can also be maintained easily, quickly and inexpensively, but which also prevents the valves from "freezing". should be completely avoided, and which should at the same time enable energy-efficient heating of the valve spindle housing, should be resistant to the salts and acids used in high-temperature energy technology, and which should also be used under very extreme conditions, such as daily outside temperature fluctuations in the range of minus 10 °C above the dew point up to plus 60 °C, an extremely high humidity, with a heating temperature of the heating sleeve of up to a maximum of 750 °C, a highly precise and very reliable temperature control over a long service life is to be guaranteed, and which is also easy to manufacture in terms of production technology en can.

According to the invention, this object is achieved by an electrical heating sleeve 1 for valve spindle housings 2 used in high-temperature energy technology, according to the features of the main claim of the invention. Advantageous designs, details and features of the invention result from the dependent claims and from the following description of the exemplary embodiment according to the invention in connection with the exemplary embodiment of five representations of a possible design of the solution according to the invention.

The illustrations show in the

FIG. 1: an electrical heater for valve spindle housing 2 used in the prior art, in high-temperature energy technology, which consists of an electrical tubular heating element 6 wound around the respective valve spindle housing 2;

FIG. 2: a half-shell 3 of the heating collar 1 according to the invention for heating the valve spindle housing 2 of the valves used in high-temperature energy technology, in a plan view;

FIG. 3: the side view of the half-shell 3 shown in FIG. 2 of the heating sleeve 1 according to the invention;

FIG. 4: the three-dimensional representation of the heating collar 1 according to the invention in an assembly drawing, this consisting of two identical half-shells 3 according to the invention, shown in FIGS. 2 and 3;

FIG. 5: a heating sleeve 1 according to the invention with thermal insulation 14 mounted on a valve spindle housing 2, according to FIG. 4, ie in the thermally insulated final assembly state, in plan view; Figure 6: the sectional view at AA, according to Figure 5.

The electrical heating sleeve 1 according to the invention shown in Figures 2 to 6 for valve spindle housing 2 used in high-temperature energy technology consists of two identically constructed, i.e. identically constructed, half-shells 3 made of cast material shown in Figures 2 and 3, which serve as a contact surface to the Coat of the valve stem housing 2 has an inner contour 4, and the outside has an approximately cylindrical outer surface 5.

As shown in FIGS. 2 and 3, in each of the half-shells 3 an originally linear electrical tubular heating element 6 deformed in a meandering manner by bending is cast in such a way that its electrical connection points open into a terminal box 7 arranged on the heating collar 1 .

The casting of the tubular heating elements in the half-shells 3 results in a stable and secure construction of the respective half-shell 3, which enables the heating sleeves 1 to be used in a robust, reliable manner even under the most extreme operating conditions.

The size and heating capacity of the heating sleeves 1 used in each case can be optimally adapted to the valve spindle housing design to be heated by the sand casting process used in the production of the half-shells 3 .

The tubular heating elements 6 are always arranged in the half-shells 3 and cast there in such a way that an even heat distribution is ensured on the inner surface, the inner contour 4 of the heating sleeve 1 . According to the invention is that in the connection area of the two half-shells 3 mounting brackets 8 are always arranged to connect the two half-shells 3 to each other.

In the present exemplary embodiment, both half-shells 3 are screwed together via six cast-on mounting brackets 8 . The use of mounting brackets 8 makes it possible to quickly mount and dismantle the heating sleeves 1 according to the invention. Advantageously, 8 through holes 17 for receiving clamping screws 18 are arranged in these mounting brackets.

In the present exemplary embodiment, a through hole 17 is arranged in each of the mounting brackets 8 .

By using clamping screws 18 arranged in these through bores 17, the two half-shells can be screwed together after they have been placed around the valve spindle housing 2, as shown in FIGS.

However, it is also important that the inner contour 4 of the half-shells 3 can be optimally and precisely adapted in size and shape to the outer contour, i.e. also to the outer diameter of the valve spindle housing 2 to be heated, by mechanical processing after casting, so that a very energy-efficient Heating of the valve stem housing 2 is guaranteed. It is also characteristic that a separate terminal box 7 for the power supply is arranged on each of the half-shells 3 of identical construction.

This makes it possible for each half-shell 3 of the heating sleeve 1 to be easily and inexpensively replaced separately and also maintained separately within the scope of maintenance at a reasonable cost.

In addition, this ensures redundancy, which, for example, in the event of the failure of a thermocouple 11, ensures rapid error detection and continued operation until repairs are made, thereby improving reliability.

According to the invention, the cast material of the half-shells 3 consists of the brass alloy CC761S.

This brass alloy is resistant to salt water and can be operated continuously up to a temperature of 700°C and a maximum of up to a temperature of 750°C.

It is also important that the material 1.4541 (X6CrNiTi18-10) is used as the casing 15 for the tubular heating element 6 . In combination, the materials used, i.e. the respective casting material used according to the invention in conjunction with the steel alloy used according to the invention for the casing 15 of the tubular heating element 6, cause the tubular heating element 6 to withstand the casting temperature due to the joint expansion behavior of these materials used according to the invention during casting.

The encapsulated tubular heaters used in the exemplary embodiment according to the invention have a diameter of 6 mm.

It is also essential to the invention that a spacer tube 9 is arranged between the half-shell 3 and the terminal box 7 assigned to it, which also distances the terminal box 7 from the lateral surface 5 of the half-shell 3 and stabilizes it safely and reliably, and in addition to safe cable routing, also the installation of others assemblies enabled.

It is essential that the spacer tube 9 is cast into the respective half-shell 3 or is firmly/rigidly anchored in an adapter plate 16 hard-soldered to the half-shell 3 .

In the present exemplary embodiment, the spacer tube 9 consists of a U-profile made of the material 1.4301 (X5CrNi18-10) and is firmly anchored in the sprue nozzle 16 in the respective half-shell 3 .

It is also essential to the invention that the end regions 10 of the tubular heating element 6 arranged in the spacer tube 9 are designed as cold ends 10 (i.e. without heating coils).

The electrical connection of the tubular heating elements ends in the terminal box 7.

The construction according to the invention, with the spacer tube 9 according to the invention and the end regions 10 of the tubular heating element 6 arranged according to the invention as cold ends 10 in the spacer tube 9, causes a thermal decoupling according to the invention of the terminal box 7 with the electrical connection points of the lateral surface 5 of the heating sleeve 1, which then ensures reliable continuous operation the heating sleeve 1 according to the invention at high operating temperatures of up to 750 ° C allows. It is also important that the terminal box 7 itself consists of stainless steel, as a result of which the entire heating sleeve 1 can be designed very cost-effectively in such a way that the degree of protection IP67 is guaranteed.

It is also essential that a thermocouple 11 is arranged in the spacer tube 9, which serves as a measuring system for temperature control in order to prevent the respective valves from “freezing”.

It is also characteristic that the measuring point 12 of the thermocouple 11 is arranged in a bore 13 in the half-shell 3, which ensures a very short reaction time for temperature regulation.

In the present embodiment, a thermocouple 11 type K is used.

It is also essential to the invention that thermal insulation 14 is arranged around the outer lateral surface 5 of the half-shell 3 and its thickness dimensions correspond approximately to the length of the spacer tube 9 .

As a result, not only a highly precise and very reliable temperature control of the valve spindle housing 2, but also a very heating cost-optimized temperature control of the valve spindle housing 2 is ensured by means of the heating collar 1 according to the invention.

It is also important that the thermocouple 11 is arranged in the spacer tube 9 and in the bore 13 of the half-shell 3 so that it can be replaced.

As a result, the thermocouple 11 can also be replaced separately, very easily, quickly and inexpensively, or maintained.

By means of the solution according to the invention, it has thus been possible to develop a heating sleeve 1 for heating a valve spindle housing 2 for valves used in high-temperature energy technology, which can be installed easily and quickly, but can also be maintained easily, quickly and inexpensively, but which also prevents "freezing" of the valves is completely avoided and at the same time enables energy-efficient heating of the valve stem housings 2, is resistant to the salts and acids used in high-temperature energy technology, and which is also used under very extreme conditions, such as everyday ones Outside temperature fluctuations in the range from minus 10 °C above the dew point to plus 60 °C, an extremely high humidity, with a heating temperature of the heating jacket of up to a maximum of 750 °C, a highly precise and very reliable temperature control is guaranteed over a long service life, and that too can be easily manufactured in terms of manufacturing technology.

Compilation of reference numbers

1 heating sleeve

2 valve stem housing

3 half shell

4 inner contour

5 lateral surface

6 tubular heaters

7 terminal box

8 mounting tab

9 spacer tube

10 cold ends

11 thermocouple

12 measuring point

13 hole

14 thermal insulation

15 sheath

16 sprue nozzles

17 through hole

18 tension screw

Claims

patent claims

1. Electric heating sleeve (1) for heating a valve spindle housing (2) in valves used in high-temperature energy technology with two half-shells (3) made of cast material, which have an inner contour (4) as a contact surface on the inside and an approximately cylindrical outer surface (5) on the outside , wherein in each of the half-shells (3) an originally linear electrical tubular heating element (6) deformed in a meandering manner by bending is cast in such a way that its electrical connection points are arranged in a terminal box (7) for electrical power supply arranged on the heating collar (1). , characterized,

- That the two half-shells (3) are completely identical, and

- that in the connection area of the two half-shells (3) mounting brackets (8) are arranged,

- that the inner contour (4) of the half-shells (3) is adapted in size and shape to the outer contour of the respective valve stem housing (2), and

- that on each of the half-shells (3) a separate terminal box (7) is arranged for power supply, and

- a spacer tube (9) is arranged between the half-shell (3) and the terminal box (7) assigned to it, and

- that the spacer tube (9) is firmly/rigidly anchored in the respective half-shell (3), and

- that the end regions of the tubular heating element (6) arranged in the spacer tube (9) are designed as cold ends (10) (i.e. without heating coils), and

- that a thermocouple (11) is arranged in the spacer tube (9), and

- that the measuring point (12) of the thermocouple (11) is arranged in a bore (13) in the half-shell (3), and

- that around the outer lateral surface (5) of the half-shell (3) around a heat insulation (14) corresponding approximately in its thickness dimensions to the length of the spacer tube (9) is arranged.

2. Electrical heating sleeve (1) according to claim 1, characterized in that the casting material of the half-shells (3) consists of the brass alloy CC761S.

3. Electrical heating sleeve (1) according to claim 1 and/or 2, characterized in that the tubular heating elements (6) have a casing (15) made of steel.

4. Electrical heating jacket (1) according to claim 3, characterized in that the material 1.4541 (X6CrNiTi18-10) is used as the casing (15) for the tubular heating elements (6).

5. Electrical heating sleeve (1) according to one of claims 1 to 4, characterized in that the spacer tube (9) consists of the material 1.4301 (X5CrNi18-10).

6. Electrical heating jacket (1) according to any one of claims 1 to 5, characterized in that on each of the half-shells (3) a sprue (16) is arranged, in which the spacer tube (9) is cast.

7. Electrical heating collar (1) according to any one of claims 1 to 5, characterized in that the spacer tube (9) is firmly anchored in an adapter plate (16) hard-soldered to the half-shell (3).

8. Electrical heating jacket (1) according to any one of claims 1 to 6, characterized in that the terminal box (7) consists of stainless steel. 14

9. Electrical heating jacket (1) according to any one of claims 1 to 8, characterized in that the thermocouple (11) is arranged interchangeably in the spacer tube (9) and in the bore (13) of the half-shell (3).

10. Electrical heating jacket (1) according to any one of claims 1 to 9, characterized in that in the mounting brackets (8) through holes (17) for clamping screws (18) are arranged.