Electric heating device

Abstract

The present invention provides an electric heating device (1) comprising at least an electric furnace (2) having walls (2A, 2B) defining a space (3), a first row (4) of tubes (10) extending through the space (3), the tubes (10) having an inlet (11) and an outlet (12) outside the space (3), a second row (14) of tubes (10) extending through the space (3), the tubes (10) having an inlet (11) and an outlet (12) outside the space (3), and a first set (5) of electric radiant heating elements (20) disposed within the space (3), the first set (5) comprising electric radiant heating elements (20) disposed between the first row (4) and the second row (14) of tubes (10).

Description

Technical Field

[0001] The present invention relates in particular to an electric heating device for performing a gas conversion reaction or for heating a fluid at high temperature.

Background Art

[0002] Various electric heating reactors are well known in the art.

[0003] As an example, WO 2020 / 002326 (A1) discloses a reactor configuration comprising at least one electric heating 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.

Summary of the Invention

Problems to be Solved by the Invention

[0004] A problem associated with the above or other well-known electric reactors is that well-known electric reactors use the furnace wall to support the electric radiant heating element.

[0005] Another problem is that local overheating of at least one electric radiant heating element may occur.

[0006] A further problem is that the furnace needs to be shut down in case of premature failure or aging of the electric radiant heating element.

[0007] An object of the present invention is to overcome or minimize one or more of the above or other problems.

[0008] A further object of the present invention is to provide an alternative electric heating device, particularly for high temperature reactions (such as above 400 °C), fluid heating at high temperature, and large-scale applications (using a large number of tubes).

Means for Solving the Problems

[0009] One or more of the above or other purposes is at least: - An electric heating furnace having a wall that defines the space, -A first row of tubes extending through space, the tubes having an inlet and an outlet outside the space, -A second row of tubes extending through space, the tubes having an inlet and an outlet outside the space, -This can be achieved by providing an electric heating device comprising a first set of electric radiant heating elements arranged in space, wherein the first set comprises an electric radiant heating element between a first row of tubes and a second row of tubes. [Effects of the Invention]

[0010] Surprisingly, according to the present invention, it has been found that the apparatus according to the present invention can provide precise temperature control of pipes and the fluids flowing through them in apparatus intended for large-scale applications (where a large number of pipes are used). As a result, the generation of undesirable by-products (such as coke formation) is reduced, and the operating time of the apparatus can be extended.

[0011] A further advantage of the present invention is that, even when a large number of tubes are present, the device has a remarkably simple and compact design (for a given number of tubes). Considering the compact design, fewer electric radiant heating elements may be required. This compact design reduces the furnace space exposed to external ambient conditions, resulting in less heat loss and thus more economical operation.

[0012] Furthermore, in the event of premature failure or deterioration of the electric radiant heating element, the electric radiant heating element can be replaced in a relatively easy manner without requiring the shutdown of the device.

[0013] The present invention will be further described below with reference to the following non-limiting drawings.

[0014] The following is shown. [Brief explanation of the drawing]

[0015] [Figure 1] This is a schematic side view of a first embodiment of the apparatus according to the present invention. [Figure 2] Figure 1 is a schematic top view of the apparatus. [Figure 3] This is a schematic side view of a second embodiment of the apparatus according to the present invention. [Figure 4] Figure 3 is a schematic top view of the apparatus. [Modes for carrying out the invention]

[0016] Those skilled in the art will readily understand that electric heating devices can vary widely and may include several additional elements. Since those skilled in the art are familiar with the methods of designing electric heating devices, this will not be described in detail here.

[0017] As described above, the apparatus comprises an electric heating furnace having walls that define the (furnace) space. These furnace walls typically include some refractory and insulating material to prevent excessive heat leakage to the outside of the furnace. The electric heating furnace may have some non-electric 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 electric heating.

[0018] The first and second rows of tubes passing through the space may be broadly modified, provided that the tubes have inlets and outlets outside the space. As mere examples, the tubes do not have to be (preferably) straight, and may have, for example, S-shaped or U-shaped forms. If U-shaped tubes are used, both the inlet and outlet of the tube may be on one side (e.g., the top). Preferably, the first and second rows of tubes extend substantially parallel to each other. If the apparatus is in the form of a reactor (and therefore not used merely for heating), the tubes may be referred to as "reactor tubes".

[0019] The first set of electric radiant heating elements (arranged within the furnace space) is not particularly limited. Typically, for heating the electric radiant heating elements, electric resistance heating is used (utilizing the "Joule effect"). Generally, the electric radiant heating elements are suitable for heating up to temperatures exceeding 300°C. Preferably, the electric radiant heating elements are suitable for heating to temperatures in the range of 400 - 1600°C. Preferably, the electric radiant heating elements include NiCr, SiC, MoSi2 or FeCrAl-based resistance heating elements. Preferably, the electric radiant heating elements are made of SiC because this material maintains its strength under high-temperature conditions (thus eliminating the need for support walls within the furnace space).

[0020] One skilled in the art will readily understand that the electric radiant heating elements can take many different shapes such as rods, plates, sheets, grids, and (for example, ceramic) rods with heating wires wound around them.

[0021] According to the present invention, the first set of electric radiant heating elements comprises at least electric radiant heating elements between a first row of tubes and a second row of tubes. These heating elements of the first set between the first row of tubes and the second row of tubes may be positioned one above the other or adjacent to each other depending on the settings of the device, but preferably, they are positioned one above the other. In addition to the heating elements between the first row of tubes and the second row of tubes, the first set may comprise further electric radiant heating elements.

[0022] According to a preferred embodiment of the device according to the present invention, the first set of electric radiant heating elements comprises electric radiant heating elements between the side wall of the space and the first row of tubes. If there are multiple rows of tubes, then preferably, the heating elements are present between the side wall of the space and the row of tubes closest to the side wall. The presence of heating elements between the side wall of the space and the row of tubes closest to the side wall makes it possible to minimize the non-uniformity of the heat flux (on the surface of the tubes) caused by the outer cold surfaces.

[0023] Furthermore, the device comprises a third tube bank and further tube banks, and it is preferable that the electric radiant heating elements are positioned between the banks. Thus, in the latter case, the first set of electric radiant heating elements comprises electric radiant heating elements between each of the tube banks. Also in this case, the first set of heating elements may include several heating elements between each tube bank, and preferably such heating elements are positioned on top of each other between each tube bank.

[0024] According to a preferred embodiment, each tube bank comprises at least 10 tubes. Preferably, the tubes in a particular bank extend substantially parallel.

[0025] Furthermore, it is preferable that the tubes extend substantially in the vertical direction. In such a vertical arrangement of the tubes, it is preferable that the fluid flowing through the tubes flows downward. Thus, in this case, the inlet of the tube is at the top and the outlet is at the bottom.

[0026] According to a particularly preferred embodiment of the device according to the invention, the device further comprises a second set of electric radiant heating elements arranged in the space, and the second set of heating elements extends substantially perpendicular to the first set of heating elements.

[0027] In this way, the first set and the second set (and further sets) of heating elements form a "grid-like" pattern, thereby increasing the uniformity of heat transfer from the heating elements to the surroundings of the tubes. The second set of electric radiant heating elements may be the same or similar to the first set of heating elements.

[0028] Furthermore, it is preferable that the electric radiant heating elements extend substantially in the horizontal direction.

[0029] To avoid excessive overheating of the tubes, it is preferable that the electric radiant heating elements do not contact the tubes directly. In other words, the heating elements and the tubes do not contact each other at least within the furnace space. [[ID=z5]]

[0030] While heating elements can take many forms, electric radiant heating elements are particularly preferably in the form of tubular heating elements, i.e., rods. A suitable example of a tubular heating element is a commercially available silicon carbide (SiC) rod.

[0031] Such tubular SiC heating elements also allow for a compact design of the furnace space because the tubular heating elements are self-supporting. As a result, support walls for the heating elements within the furnace space are not required. Preferably, the furnace space has no walls at all to support the tubular heating elements.

[0032] In a further embodiment, the present invention provides a method for carrying out a fluid conversion reaction or heating using an electric heating device according to the present invention, the method comprising at least the following steps:

[0033] a) supplying a feed flow through the inlet of a pipe; b) subjecting the feed flowing through the pipe to a fluid transformation reaction or heating within the space of the apparatus using heat generated by an electric radiant heating element, thereby obtaining one or more reaction products or a heated feed flow; and c) removing one or more reaction products or a heated feed flow from the apparatus through the outlet of the pipe.

[0034] For the purposes of this explanation, the same reference number refers to the same or similar component.

[0035] In the embodiments shown in Figure 1 (and Figure 3), the electric heating apparatus of Figure 1 is generally indicated by reference numeral 1 and is shown as a reactor. However, it will also be readily apparent to those skilled in the art that the apparatus may be used to heat a fluid, i.e., to prevent a reaction from occurring.

[0036] The reactor 1 in Figure 1 comprises an electric heating furnace 2 having walls defining a furnace space 3 inside, a first row 4, a second row 14, and a third row 24 of reaction tubes 10, and a first set 5 of electric radiant heating elements 20. In Figure 1, only the side walls 2A and 2B are shown. However, those skilled in the art will understand that in the case of a rectangular reactor, there are four side walls, a top, and a bottom.

[0037] The first set 5 of the electric radiant heating elements 20 is arranged within the space 3. The first set 5 comprises several electric radiant heating elements 20 positioned vertically relative to each other between the first row 4 and the second row 14 of the reaction tube 10. Furthermore, the first set 5 comprises additional electric radiant heating elements 20 between the side wall 2A of the space 3 and the first row 4 of the reaction tube 10, and between the side wall 2B and the third row 24 of the reaction tube 10.

[0038] As shown in Figure 1, the reaction tube 10 extends through space 3 and has an inlet 11 and an outlet 12 outside space 3. Furthermore, the reaction tube 10 extends in a substantially vertical manner.

[0039] As can be seen further in Figure 1, the electric radiant heating element 20 is tubular and extends substantially horizontally. Furthermore, the electric radiant heating element 20 is not in direct contact with the reaction tube 10.

[0040] The walls 2A and 2B of the furnace 2 are typically made of a heat-resistant structural material and may be insulated to prevent excessive heat leakage from the inside to the outside of the furnace 2.

[0041] During the use of the reactors in Figures 1 and 2, a fluid flow (typically a gas) is supplied through the inlet 11 of the reactor tube 10. The supply flow then flows through the reactor tube 10 and is subjected to a fluid transformation reaction in the space 3 of the reactor 1 (and in the reactor tube 10) using heating such as that generated by the electric radiant heating element 20, thereby obtaining one or more reaction products.

[0042] Next, one or more reaction products are removed from the reactor 1 via the outlet 12 of the reactor tube 10.

[0043] Figures 3 and 4 show a side view and a top view of a second embodiment of the apparatus according to the present invention (in this case also in the form of a reactor), the reactor 1 further comprising a second set 6 of electric radiant heating elements 20 arranged in space 3. The heating elements 20 of the second set 6 extend substantially perpendicular to the heating elements 20 of the first set 5, thereby obtaining a grid-like pattern of heating elements (when viewed from above).

[0044] Those skilled in the art will readily understand that many modifications can be made without departing from the scope of the present invention.

Claims

1. Electric heating device (1), - An electric heating furnace (2) having walls (2A, 2B) that define space (3), - A first row (4) of pipes (10) extending through the space (3), wherein the pipes (10) have an inlet (11) and an outlet (12) outside the space (3), - A second row (14) of pipes (10) extending through the space (3), wherein the pipes (10) have an inlet (11) and an outlet (12) outside the space (3), - An electric heating device (1) comprising at least a first set (5) of electric radiant heating elements (20) arranged in the space (3), wherein the first set (5) comprises electric radiant heating elements (20) arranged between the first row (4) and the second row (14) of the tube (10).

2. The apparatus (1) according to claim 1, wherein the first set (5) of the electric radiant heating elements (20) comprises electric radiant heating elements (20) between the side wall (2A) of the space (3) and the first row (4) of the pipe (10).

3. The apparatus (1) according to claim 1 or 2, wherein the apparatus (1) comprises a third row (24) and further rows of tubes (10), and an electric radiant heating element (20) is positioned between the rows (4, 14, 24).

4. The apparatus (1) according to any one of claims 1 to 3, wherein each row (4, 14, 24) of the pipe (10) comprises at least 10 pipes (10).

5. The apparatus (1) according to any one of claims 1 to 4, wherein the pipe (10) extends substantially vertically.

6. The apparatus (1) according to any one of claims 1 to 5, further comprising a second set (6) of electric radiant heating elements (20) arranged in the space (3), wherein the heating elements (20) of the second set (6) extend substantially perpendicular to the heating elements (20) of the first set (5).

7. The apparatus (1) according to any one of claims 1 to 6, wherein the electric radiant heating element (20) extends substantially horizontally.

8. The apparatus (1) according to any one of claims 1 to 7, wherein the electric radiant heating element (20) is not in direct contact with the tube (10).

9. The apparatus (1) according to any one of claims 1 to 8, wherein the electric radiant heating element (20) is a tubular heating element.

10. A method for carrying out a fluid conversion reaction or heating using an electric heating device according to any one of claims 1 to 9, wherein the method comprises at least: A method comprising: a) supplying a supply flow through the inlet of the pipe; b) subjecting the supply flow flowing through the pipe to a fluid transformation reaction or heating within the space of the apparatus using heat generated by the electric radiant heating element, thereby obtaining one or more reaction products or a heated supply flow; and c) removing the one or more reaction products or a heated supply flow from the apparatus through the outlet of the pipe.

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