Electric heating device

Abstract

The present invention relates to an electric heating device (1), comprising at least an electrically heated furnace (2) having a roof (2A) and walls defining a space (3); at least one tube (10) extending through the space (3), the at least one tube (10) having an inlet (11) and an outlet (12) outside the space (3); - an electric radiant heating element (20) arranged in the space (3) and capable of heating at least one tube (10), The heating element (20) is suspended from the roof (2A) of the space (3); The roof (2A) of the space (3) provides an electric heating device, the shape of which is adapted to have heating elements (20) suspended at different heights.

Description

[Technical field]

[0001] The present invention particularly relates to an electric heating device for carrying out gas shift reactions or for heating fluids at high temperatures. [Background technology]

[0002] A variety of electrically heated reactors are well known in the art.

[0003] As an example, WO 2020 / 002326 A1 discloses a reactor configuration comprising at least one electrically heated furnace defining a space, with at least one reaction tube positioned within the furnace space. The reaction tube is heated using at least one electric radiant heating element.

[0004] A problem associated with these and other known electric reactors is that in the event of premature failure or aging of the electric radiant heating elements, shutdown or (personal) entry into the furnace space is often required. This results in long-term interruptions of the furnace and related processes, with associated interruptions in production. Particularly in the case of large units (>50 MW) for which the present invention is specifically contemplated, this can result in very high costs due to loss of production.

[0005] Another problem is that when brittle ceramic materials are used for the heating elements, the breakage can have a potential domino effect (i.e., affecting other heating elements) if a broken heating element falls on a heating element positioned below. A similar effect can occur when certain metal heating elements are used, but this involves molten metal falling on a heating element positioned below, thereby causing an electrical failure.

[0006] It is an object of the present invention to overcome or minimize one or more of the above or other problems.

[0007] It is a further object of the present invention to provide an alternative electric heating device that is particularly suitable for high temperature reactions (such as above 400° C.), fluid heating at high temperatures, and large scale (above 50 MW) applications (using multiple tubes). Summary of the Invention

[0008] One or more of the above or other objects are achieved by providing an electric heating device comprising at least an electric heating furnace having a roof and walls defining a space; at least one tube extending through the space, the at least one tube having an inlet and an outlet outside the space; an electric radiant heating element arranged in the space, the electric radiant heating element being capable of heating at least one tube, The heating element is suspended from the roof of the space; The roofing of the space can be achieved by providing an electric heating device having a shape configured to have heating elements suspended at different heights.

[0009] Surprisingly, according to the invention it has been found that electric radiant heating elements as used in an apparatus according to the invention can be easily replaced in the event of premature failure or deterioration of the electric radiant heating element with time, without requiring shutdown of or (personal) entry into the furnace space.

[0010] Furthermore, it has been found that the apparatus according to the invention can provide precise temperature control of the tubes and the fluids flowing therethrough in apparatus intended for large scale (greater than 50 MW) applications (where multiple tubes are used), resulting in less unwanted by-products (such as coke formation) and longer uptime of the apparatus.

[0011] Another advantage of the apparatus according to the invention is that by arranging the heating elements at different heights, the heating elements can heat the tube over the entire length of the tube, which is typically longer than the length of the individual heating elements.

[0012] A further advantage of the present invention is that its principles can be applied to existing equipment by making appropriate adaptations.

[0013] Those skilled in the art will readily appreciate that the electric heating device may vary widely and may include a number of additional elements, which will not be described in detail herein, as those skilled in the art are familiar with how to design an electric heating device.

[0014] As mentioned above, the apparatus comprises an electrically heated furnace having a roof and walls which, together with the bottom, define a (furnace) space. The walls, roof and bottom of the furnace typically include some refractory material and insulation to avoid excessive heat leakage outside the furnace. Electrically heated furnaces may also have some non-electrical heating (other than that provided as a result of the exothermic reaction), but preferably at least 50%, preferably at least 80%, and most preferably all of the heating is provided by electrical heating.

[0015] As mentioned above, the roof of the furnace space of the device according to the invention has a shape that is adapted to have heating elements suspended at different heights. For this purpose, the roof can have a shape such that the roof is at an angle from the vertical, preferably using a stepped shape. According to a preferred embodiment of the device according to the invention, the roof has a shape selected from the group consisting of a gable shape, a stepped shape, some stepped shapes, preferably some stepped shapes. This allows the heating elements to be suspended at different heights (and provide heat to different parts of the tube(s)). In this respect, the skilled person will easily understand that not all heating elements need to be suspended at different heights. For example, if rows of heating elements are used, the heating elements in the same row are typically suspended at the same height.

[0016] Furthermore, the heating element is preferably removably connected to the roof of the space, preferably by means of a closable opening in the roof, so that the heating element can be replaced through the roof. This allows easy access to the heating element and provides the possibility to replace it in case of premature failure or ageing even during operation of the device. If the heating element is replaced during operation of the furnace, the replacement is preferably performed in a pressure box in order to maintain the pressure in the furnace at an appropriate level (and to avoid excessive heat from within the furnace leaving the furnace).

[0017] At least one tube (but typically several tubes) passing through the space may be widely varied, so long as the tube has an inlet and an outlet outside the space. By way of example only, the tube need not be straight (although preferred), but may have, for example, an S-shape or a U-shape. If a U-shaped tube is used, both the inlet and the outlet of the tube may be on one side (e.g., at the top). If several tubes are present, the tubes preferably run substantially parallel. If the device is in the form of a reactor (and therefore not used solely for heating), the tube may be referred to as a "reactor tube". The tube may be formed in the form of a coil, i.e., helically.

[0018] The electric radiant heating element (placed in the furnace space) is not particularly limited. Typically, for heating the electric radiant heating element, electric resistance heating is used (utilizing the "Joule effect"). In general, the electric radiant heating element is suitable for heating to temperatures above 300°C. Preferably, the electric radiant heating element is suitable for heating to temperatures in the range of 400-1600°C. Preferably, the electric radiant heating element comprises a NiCr, SiC, MoSi2 or FeCrAl based resistance heating element.

[0019] Those skilled in the art will readily appreciate that electric radiant heating elements can take many different forms, such as rods, plates, sheets, grids, (e.g., ceramic) rods with heating wire wrapped around the rod.

[0020] Typically, the length of the heating element is shorter than the length of the tube(s), and therefore, several separate heating elements are usually used to heat the tube(s) over their entire length.

[0021] According to a preferred embodiment, the device comprises at least 10 tubes extending through the space. Preferably, the tubes extend substantially parallel.

[0022] Furthermore, the tube(s) preferably extend in a substantially vertical direction. In such a vertical configuration of the tubes, the fluid flowing through the tubes preferably flows downwards. Thus, in this case, the inlet of the tube is at the top and the outlet is at the bottom.

[0023] To avoid excessive overheating of the tubes, it is preferred that the electric radiant heating elements are not in direct contact with the tubes, in other words the heating elements and the tubes do not contact each other, at least within the furnace space.

[0024] Although the heating element may have many forms, it is particularly preferred that the electric radiant heating element be in the form of a tubular heating element, i.e., a rod. An example of a suitable tubular heating element is a silicon carbide (SiC) rod, which is commercially available.

[0025] Such tubular SiC heating elements allow a compact design of the furnace space to be achieved.

[0026] In a further aspect, the present invention provides a method for carrying out a fluid transformation reaction or heating using an electric heating device according to the present invention, the method comprising at least the following steps: a) providing a feed stream through an inlet of a tube; b) subjecting the feed stream flowing through the tubes to a fluid transformation reaction or heating within the volume of the apparatus using heat, such as that generated by an electrical radiant heating element, thereby obtaining one or more reaction products or a heated feed stream; c) removing one or more of the reaction products or heated feed streams from the apparatus via an outlet of the tube.

[0027] Although not limited thereto, the method according to the invention is particularly directed to heating or fluid conversion reactions in large scale applications (greater than 50 MW).

[0028] Those skilled in the art will readily appreciate that the nature of the fluid conversion reaction is not particularly limited. Non-limiting preferred examples include SMR (steam methane reforming), steam cracking, etc. [Brief description of the drawings]

[0029] The invention will now be further illustrated by the following non-limiting figures, in which: [Figure 1] 1 is a schematic side cross-sectional view of an apparatus having a stepped gable configuration in accordance with the present invention; [Diagram 2] FIG. 2 is a schematic top view of the device of FIG. 1. [Diagram 3] 1 is a schematic cross-sectional top view of an apparatus according to the present invention; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0030] For purposes of this description, the same reference numbers refer to the same or similar components.

[0031] In the embodiment of Figure 1, the electric heating device of Figure 1 is generally designated by the reference numeral 1 and is shown as a reactor, however, those skilled in the art will readily appreciate that the device may also be used to heat a fluid, i.e., such that no reaction takes place.

[0032] The reactor 1 in FIG. 1 comprises an electrically heated furnace 2 having a roof 2A, a bottom 2B, and walls 2C defining a furnace space 3 therein, a number of reaction tubes 10 (only one is shown in FIG. 1), and a number of electric radiant heating elements 20.

[0033] Electric radiant heating elements 20 are disposed within the space 3 and suspended from the roof 2A. Because the roof 2A of the space 3 has a somewhat stepped gable shape, the heating elements are suspended at different heights (although heating elements in the same row are typically suspended at the same height). The heating elements 20 are removably connected to the roof 2A of the furnace space 3, which in the embodiment of Figure 1 is a closable opening 4 in the roof 2A.

[0034] 1, the reaction tube 10 extends through the space 3 and has an inlet 11 and an outlet 12 outside the space 3. Furthermore, the reaction tube 10 extends in a substantially vertical direction.

[0035] As can be further seen in FIG. 1, the electric radiant heating elements 20 are not in direct contact with the reactor tube 10 .

[0036] The roof 2A, bottom 2B and walls 2C of the furnace space 2 are typically made from heat-resistant structural materials and may be insulated to avoid excessive leakage of heat from inside the furnace 2 to its outside.

[0037] In the event of premature failure or deterioration over time of the electric radiant heating elements 20 as used in the reactor 1 according to the invention, these heating elements can be easily replaced (through a closable opening 4 in the roof 2A) without requiring shutdown of the reactor 1 or personal entry into the reactor 1.

[0038] If the heating element 20 is replaced during operation of the reactor, the replacement is preferably performed within a pressure box (not shown) to maintain the pressure within the furnace space 3 at an appropriate level (and to avoid excessive heat from within the furnace space 3 exiting the reactor).

[0039] As seen in front view in FIG. 2, the reactor 1 includes an array of four parallel tubes 10 .

[0040] As can be clearly seen from the top view in FIG. 3, all the heating elements 20 are easily accessible from the roof 2A (which has a somewhat stepped gable shape) of the reactor 1.

[0041] 1 and 3, a fluid stream (typically a gas) is fed through inlet 11 to reactor tube 10. The fluid stream flowing through reactor tube 10 is then subjected to a fluid transformation reaction in (reactor tube 10 within) space 3 of reactor 1 using heating, such as generated by electrical radiant heating elements 20, thereby producing one or more reaction products.

[0042] One or more reaction products are subsequently removed from reactor 1 via outlet 12 of reactor tube 10.

[0043] Those skilled in the art will readily appreciate that numerous modifications can be made without departing from the scope of the present invention.

Claims

1. An electric heating device, which has at least, - An electric heating furnace having a roof and walls that define the space, - At least one tube extending through the space, having an inlet and an outlet outside the space, - An electric radiant heating element arranged in the space, which is capable of heating the at least one tube, The heating element is suspended from the roof of the space, The roof of the space has a shape configured to have heating elements suspended at different heights, The aforementioned roof has a shape selected from the group consisting of a gable shape, a stepped shape, and a tiled shape, and is used for electric heating devices.

2. The apparatus according to claim 1, wherein the heating element is detachably connected to the roof of the space such that the heating element can be replaced via the roof through a closable opening in the roof.

3. The apparatus according to claim 1 or 2, comprising at least 10 tubes extending through the space.

4. The apparatus according to claim 1 or 2, wherein the pipe extends substantially vertically.

5. The apparatus according to claim 1 or 2, wherein the electric radiant heating element is not in direct contact with the tube.

6. A method for carrying out a fluid conversion reaction or heating using an electric heating device according to claim 1 or 2, wherein the method comprises at least: a) A step of supplying the supply flow through the inlet of the pipe, b) A step of subjecting the supply flow flowing through the pipe to a fluid conversion reaction or heating within the space of the apparatus using the heat generated by the electric radiant heating element, thereby obtaining one or more reaction products or heated supply flow, c) A method comprising the step of removing one or more reaction products or heated supply streams from the apparatus through the outlet of the pipe.

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