Device for measuring the inner temperature of a reforming tube

Abstract

A device for measuring the internal temperature of a reforming tube including a first structure having an axial part of tubular shape positioned in the lengthwise direction of a reforming tube and a radial part projecting radially towards the central axis of the reforming tube, a second structure of oblong shape having at least one thermocouple made of welded Nicrosil/Nisil conductors arranged longitudinally against the axial part and radially against the radial part, and an outer sheath enveloping the first structure and the second structure.

Claims

1. A device for measuring the internal temperature of a reforming tube comprising: a first structure comprising an axial part of tubular shape positioned in the lengthwise direction of a reforming tube and at least one radial part projecting radially towards the central axis of the reforming tube, a second structure comprising at least one thermocouple made of welded Nicrosil/Nisil conductors arranged longitudinally against the axial part and parallel with the radial part, and an outer sheath enveloping the first structure and the second structure, wherein the second structure is tied to the first structure.

2. The device of claim 1, wherein the Nicrosil/Nisil conductors are welded at a tip situated at the end of the radial part.

3. The device of claim 1, further comprising a reinforcing structure in the form of an arc of a circle reinforcing the retention of the device against the internal wall of the reforming tube.

4. The device of claim 1, wherein the at least one radial part of the first structure further comprises at least a first radial part and a second radial part, wherein the first radial part and the second radial part are situated at different heights on the tube, the at least one thermocouple of the second structure comprises at least a first thermocouple and a second thermocouple made of welded Nicrosil/Nisil conductors positioned parallel with, respectively, the first radial part and the second radial part and longitudinally against the axial part.

5. A device for measuring the internal temperature of a reforming tube comprising: a first structure comprising an axial part of tubular shape positioned in the lengthwise direction of a reforming tube and at least one radial part projecting radially towards the central axis of the reforming tube, a second structure comprising at least one thermocouple made of welded Nicrosil/Nisil conductors arranged longitudinally against the axial part and parallel with the radial part, and an outer sheath enveloping the first structure and the second structure, wherein a remaining space between the outer sheath, the first structure and the second structure is filled with a solder.

6. A device for measuring the internal temperature of a reforming tube comprising: a first structure comprising an axial part of tubular shape positioned in the lengthwise direction of a reforming tube and at least one radial part projecting radially towards the central axis of the reforming tube, a second structure comprising at least one thermocouple made of welded Nicrosil/Nisil conductors arranged longitudinally against the axial part and parallel with the radial part, and an outer sheath enveloping the first structure and the second structure, wherein the first structure has an upper end, and wherein the upper end of the first structure is plugged.

7. The device of claim 1, wherein the device for measuring the internal temperature of a reforming tube comprises a single unit or of several units joined together.

8. A reforming tube comprising a device for measuring the internal temperature of a reforming tube as claimed in claim 1, wherein the device is placed against an internal wall of the reforming tube.

9. The reforming tube of claim 8, wherein the reforming tube has an upper end comprising a blanking plate and the device for measuring the internal temperature of a reforming tube is installed through the blanking plate.

10. The reforming of claim 9, wherein the measuring device is connected to conventional data acquisition and storage means.

11. The reforming tube of claim 8, wherein the end of the radial part is situated at a distance of between 2 and 5 mm from the central axis of the reforming tube.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) For a further understanding of the nature and objects for the present invention, reference should be made to the following detailed description, taken in conjunction with the accompanying drawings, in which like elements are given the same or analogous reference numbers and wherein:

(2) FIG. 1a illustrates the positioning of the temperature measuring device within the reforming tube, in accordance with one embodiment of the present invention.

(3) FIG. 1b illustrates the overall structure of the temperature measuring device, in accordance with one embodiment of the present invention.

(4) FIG. 2 illustrates a profile of porosity along the tube, averaged over the cross section of the tube, in accordance with one embodiment of the present invention.

(5) FIG. 3 illustrates a view of the temperature measuring device from above, in accordance with one embodiment of the present invention.

(6) FIG. 4 illustrates a schematic side view of the reforming tube with the measuring device, in accordance with one embodiment of the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

(7) FIG. 1a shows the positioning of the temperature measuring device within the reforming tube. The device is pressed against the internal skin of the reforming tube and the circular-arc-shaped structure is there to ensure that it is held in position, notably while the tube is being filled with the catalyst.

(8) FIG. 1b shows how the heap is created around the device. Specifically, the device is supposed to measure the temperature of the gas in the catalytic bed without interfering with the heaping as this could lead to local temperature increases or cause fluidic phenomena around the thermocouple which would then lead to a biased measurement not representative of the physical reality. This result is obtained by simulation using the DigiPac software.

(9) Empty zones that would encourage preferred circulation of gas are observed around the device. However, it has been demonstrated that the risk of creating hotspots is modest, even with larger voids. FIG. 2 shows a profile of porosity along the tube, averaged over the cross section of the tube. Here, the expansion is situated at the altitude z=250 mm (z=0 being taken to be at the height of the bottom of the furnace). The disruption contributes to locally increasing the porosity by around 10%. This perturbed zone is located at the level of the expansion and below the expansion. With regard to the variations in porosity arising out of the random nature of the heaping (+1-5%), this porosity defect will not be able to generate undesirable effects that might introduce error into the temperature measurement. In other words, it is possible to consider that the heaping of the catalysts in the reforming tube comprising the temperature measuring device according to the invention is correct.

(10) FIG. 3 shows a view of the temperature measuring device from above.

(11) FIG. 4 is a schematic side view of the reforming tube with the measuring device. For better visibility, the outer sheath has not been depicted and only a portion of the reforming tube has been depicted. There are depicted: the reforming tube the first structure 2 made up of at least a part 2a of tubular shape positioned in the lengthwise direction of the tube and of an expansion 2b of this part of tubular-shaped part projecting radially towards the central axis 3 of the reforming tube, the second structure 4 of oblong shape comprising at least one thermocouple made of welded Nicrosil/Nisil conductors arranged longitudinally against the tubular-shaped part of the first structure and radially against the expansion of the first structure, the ties 7 the tip 6 at which the conductors are welded, and the reforming tube blanking plate 9.

(12) Note that the expansion of the first structure may be holed in order to allow the thermocouple to pass through.