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(11) | EP 4 472 354 A1 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | HEATER ASSEMBLY AND REACTOR ASSEMBLY |
| (57) A heater assembly (10) comprising a plurality of heating units (30). The heating
units comprise a heater pipe (35), a conductor (31) inside the heater pipe for conveying
electric current, electric insulation (33) arranged between the conductor and the
heater pipe to electrically insulate the conductor. The heating units (30) are arranged
with their radially outer surfaces of the heater pipes (35) beside each other. A reactor
assembly comprising such a heater is also disclosed.
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Technical Field
[0001] The present invention relates to a heater assembly and to a reactor assembly configured for reaction of heated materials.
Background Art
[0002] Reactor assemblies have been known for a long time. Their use includes heating of various types of matter, typically without the presence of oxygen, to obtain a chemical reaction. For example, some reactors are used to produce carbon monoxide and hydrogen from natural gas.
[0003] To heat the reactor, it is known to use a portion of the natural gas as fuel, while letting the remaining portion react. An alternative solution is to heat the natural gas with other means, for instance with an electrically powered heater assembly. Such heater assemblies typically comprise a coil to provide induction heating of a ferromagnetic and/or conductive material with alternating current.
Summary of invention
[0004] According to a first aspect of the present invention, there is provided a heater assembly comprising a plurality of heating units. The heating units comprise a heater pipe, a conductor inside the heater pipe for conveying electric current, and electric insulation arranged between the conductor and the heater pipe to electrically insulate the conductor. The heating units are arranged with their radially outer surfaces of the heater pipes beside each other.
[0005] By stating that the radially outer surfaces of the heater pipes are arranged beside each other is meant that they are not arranged longitudinally after one another in a non-overlapping fashion. Instead, they are arranged such that at least some of their respective axial distances are overlapping. Preferably, the heater pipes are arranged in parallel.
[0007] The electric insulation will typically also function as thermal insulation. A possible material of the electric insulation is a ceramic material.
[0008] In addition to the said electric insulation, the heater assembly may also comprise a thermal insulation arranged radially between the heater pipe and the electrical insulation. Such a thermal insulation may also contribute to electrical insulation. A typical material of the thermal insulation may be a ceramic material.
[0009] In some embodiments, the conductor can comprise a conductor bore for conveying a cooling fluid. The conductor may for instance be a copper tube configure to guide a cooling fluid, for instance a liquid, through its bore. This will protect the conductor from excessive heat.
[0010] The heater assembly can in some embodiments have one or more sets of three heating unit groups, wherein the respective one of the three heating unit groups connects to one of respective three power supply lines configured for connection to a three-phase power supply. The respective heating unit groups can then comprise a plurality of heating units, including a proximate heating unit and a remote heating unit. The conductors that exit the respective remote heating units of the respective heating unit groups of a common set connect to each other at a branching point.
[0011] In some embodiments, the heater assembly can comprise two sets of three heating unit groups, wherein a return inlet and a cooling outlet of a cooling fluid supply connect to a respective branching point of the respective two sets of three heating unit groups. In this manner, the cooling fluid supply can connect to the conductors at a point without voltage.
[0012] In some embodiments, the heater assembly comprises a three-phase power supply, a transformer with primary windings and secondary windings, wherein the primary windings connect to the power supply and the secondary windings connect to the conductors of the heating units. It further has a cooling fluid supply with a cooling outlet and a return inlet connected to respective cooling lines that connect to conductors on opposite sides of the plurality of heating units to form a cooling loop, as the conductors comprise conductor bores for conveying cooling fluid, and a cooling fluid pump.
[0013] In some embodiments, the heater assembly comprises a power supply in the form of a frequency converter comprising phase cells, wherein the phase cells connect to a respective power line that connect to a respective conductor.
[0014] In some embodiments, the heater pipe comprises cobalt. In such embodiments, the heater pipe can comprise cobalt cladding. In other embodiments it may comprise a cobalt-containing alloy, or it may be made of substantially cobalt. This is advantageous, since cobalt has a high Curie temperature.
[0015] According to a second aspect of the present invention, there is provided a reactor assembly comprising a vessel with a reactor chamber and a heater assembly according to the above discussed first aspect of the invention. The vessel comprises an inlet and an outlet, and the heating units are arranged inside the vessel.
[0016] In some embodiments the vessel may comprise a first and a second thermal insulation wall arranged at the respective ends of the heating units, to form a fluid barrier between the interior of the vessel (the reactor chamber) and a gap located between the conductor and the inner surface of the heater pipe.
[0017] Advantageously, the heating units can be supported at least partly by the first and second thermal insulation walls.
[0018] The reactor assembly may further comprise a first buffer chamber adjacent the first thermal insulation wall and a second buffer chamber adjacent the second thermal insultation wall, such that conductors extending out from the heating units extend into the first and second buffer chambers.
[0019] The said gaps of the heating units (radially outside of the conductors) may then form flow channels between the first and second buffer chambers.
[0020] Preferably, the reactor assembly can further comprise a pressure control unit configured to control the pressure in the first and second buffer chambers.
[0021] The reactor assembly can further comprise a buffer gas circulation system configured to circulate buffer gas between the first and second buffer chambers through the heating units. The buffer gas circulation system can comprises a buffer gas cooler, a buffer gas pump, and a buffer gas line extending between the first and second buffer chambers.
[0022] In this manner, one can cool the conductors of the heating units by flowing the buffer gas through the heating units.
[0023] Advantageously, the buffer gas circulation system may further comprise a buffer gas analyzer unit. The buffer gas analyzer unit can detect the contents of the buffer gas and thus detect if a leak has occurred from the reactor chamber into the buffer gas.
[0024] Preferably, the pressure control unit maintains a pressure in the buffer chambers that is above ambient pressure and below the pressure inside the reaction chamber.
[0025] According to a further aspect of the invention, there is disclosed a use of a reactor assembly as defined above for producing iron in a direct reduced iron process, or producing carbon black, or producing methanol from syngas.
[0026] As the skilled reader will appreciate, the reactor assembly discussed herein is well suited for high temperature processes in a closed reactor chamber.
Detailed description of the invention
[0027] While various features of the invention have been discussed in general terms above, a more detailed and non-limiting example of embodiment will be presented in the following with reference to the drawings, in which
- Fig. 1
- is a schematic illustration of a reactor assembly with a heater assembly;
- Fig. 2
- is a schematic perspective view of a heating unit;
- Fig. 3
- is another schematic perspective view of a heating unit corresponding to Fig. 2, however illustrating a somewhat different embodiment;
- Fig. 4
- is a cross section view through a heating unit;
- Fig. 5
- is a schematic illustration of two heating units connected to an electric power supply and to a cooling fluid supply;
- Fig. 6
- is a schematic illustration of four serially arranged heating units that are connected to an electric power supply and a cooling unit supply;
- Fig. 7
- is a schematic illustration of a heater assembly comprising a plurality of heating units that are connected to a three-phase electric power supply;
- Fig. 8
- is a principle cross section view through a reactor assembly with a heater assembly;
- Fig. 9
- is a principle cross section view through the reactor assembly shown in Fig. 8, however seen from another angle;
- Fig. 10
- is another principle cross section view similar to Fig. 8, however depicting another embodiment with more heating units;
- Fig. 11
- is a schematic illustration of a further embodiment, depicting in particular another electric configuration;
- Fig. 12
- is a schematic illustration resembling Fig. 11, depicting yet another electric configuration; and
- Fig. 13
- is another embodiment of a reactor assembly according to the invention.
[0028] Fig. 1 is a schematic diagram of a reactor assembly 1 according to the present invention. It comprises a vessel 3 with a reactor chamber 5. The vessel 3 has an inlet 7 and an outlet 9. Depending on the specific purpose of the reactor assembly 1, the vessel 3 may comprise a plurality of inlets 7 and/or a plurality of outlets 9. The inlet 7 is configured to guide matter that shall be treated, for instance a gas mixture, into the reactor chamber 5. The outlet 9 is configured for guiding treated matter, such as a gas mixture, out from the reactor chamber 5.
[0029] Inside the vessel 3 there is arranged a heater assembly 10 for heating the matter to be treated. The heater assembly 10 is an electric heater assembly, and thus connects to power supply lines 11 for providing electric power into the vessel 3. The power supply lines 11 extend through a wall 3a of the vessel 3, for instance by means of penetrators 12.
[0030] While Fig. 1 depicts the main components of the reactor assembly 1, a more detailed discussion of the heater assembly 10 will be given in the following.
[0031] Fig. 2 depicts a principle perspective view of a heating unit 30. The heating unit 30 comprises a conductor 31 configured for conducting electric current. The conductor 31 is, in this embodiment, made of copper. Other suitable nonferromagnetic metals, such as aluminum or silver, or superconductors, or metal alloys can also be used.
[0032] An electric insulation 33 is arranged outside the conductor 31. The electric insulation 33 can extend coaxially with the conductor 31. A suitable material of the electric insulation 33 can be a ceramic material since such materials typically will withstand heat. Thus, the electric insulation 33 can be made of a ceramic tube with a tube bore receiving the conductor 31.
[0033] The conductor 31 and electric insulation 33 is arranged inside the bore of a heater pipe 35. The heater pipe 35 is preferably made of a ferromagnetic material. The heater pipe 35 can also be made another material. Such other material can for instance be vanadium, titanium, or wolfram. The chosen material should preferably have a suitable conductivity and a reasonably high melting point. As shown in Fig. 2, there is a gap between the electric insulation 33 and the inner bore of the heater pipe 35. However, other embodiments may be without such a gap.
[0034] While the embodiments discussed herein disclose a heater pipe 35 having a circular cross section, it shall be clear that also other designs are possible. For instance, the heater pipe 35 may have a polygonal configuration, for instance as a square.
[0035] By applying alternating current through the conductor 31, the alternating electric field generated by the electric current will induce current in the heater pipe 35 in the opposite direction. This current will create heat. Thus, the heater pipe 35 can be connected to earth, typically at both pipe ends, while still being used to generate heat. If a current flows in one direction through the conductor 31, a current will then flow through the heater pipe 35 in the opposite direction.
[0036] The heating power generated in the heater pipe 35 will depend on the amount of current passed through the conductor 31, the frequency, and the conductive characteristics of the heater pipe 35. These parameters will thus be chosen according to the desired temperature (i.e. the desired heating power and target temperature).
[0037] In some embodiments, one may wish to heat to temperatures that are noncompatible with the material in the conductor 31. Furthermore, to maintain good conductivity in the conductor 31, it is desirable to maintain a low temperature in the conductor 31.
[0038] Fig. 3 depicts an embodiment of a heating unit 30 wherein the conductor 31 is made of a metal tube. In particular, in this embodiment the conductor 31 is made of a copper tube. Hence, the conductor 31 has a conductor bore 32. With such a conductor 31, one can guide a cooling fluid through the conductor bore 32 to prevent excessive temperature in the conductor 31. A typical cooling fluid can be water. However, other fluids are possible, for instance an oil or a gas.
[0039] Fig. 4 depicts a cross-section view through a heating unit 30. This heating unit 30 comprises the conductor 31 with the conductor bore 32, the electric insulation 33, and the heater pipe 35, which were also included in the schematic view of Fig. 3. Moreover, the heating unit 30 shown in Fig. 4 further comprises a thermal insulation 37 arranged between the electric insulation 33 and the heater pipe 35. Notably, in this embodiment, both the thermal insulation 37 and the electric insulation 33 will contribute to thermal insulation of the conductor 31.
[0040] The thermal insulation 37 has a tubular configuration such that it receives the electric insulation 33 in its bore. As indicated in Fig. 4, there is a first gap 34 between the electric insulation 33 and the bore of the thermal insulation 37. The first gap 34 enables thermal expansion. Moreover, there is a second gap 36 between the bore of the heater pipe 35 and the thermal insulation 37. However, in other embodiments there may be a tight fit without such gaps 34, 36. Or there may be present only one of the said gaps.
[0041] As will be discussed further below, a cooling gas can be guided through the gap (the first gap 34) that is provided radially outside the conductor 31.
[0042] The radially outwardly facing surface of the heater pipe 35 is sealed off from the inner bore of the heater pipe 35, such that the matter introduced to the reactor assembly 1 through the inlet 7 does not enter the heater pipe 35. Such separation can for instance be obtained with a thermal insulation wall 3b, 3c, which will be discussed further below (Fig. 9 and Fig. 13).
[0043] In some embodiments, the electric insulation 33 can be used both for electric insulation and for thermal insulation.
[0044] However, if for instance the electric insulation 33 is made of cross-linked polyethylene (XLPE), then the electric insulation 33 should be maintained at a temperature below 90 °C. For embodiments where the heater pipe 35 is heated to for instance 400 °C, one will also need the thermal insulation 37.
[0045] The thermal insulation 37 can for instance be made of a ceramic material, as such materials tend to tolerate high temperatures, be electrically non-conductive, and allowing the electric field from the conductor 31 to reach the heater pipe 35.
[0046] At one or both ends of the heater pipe 35, there is arranged a pipe connection flange 39. The pipe connection flanges 39 facilitates mounting of the heating unit 30 inside the vessel 3.
[0047] Fig. 5 depicts a heater assembly 10 comprising two heating units 30. The heating units 30 are schematically depicted for illustrational purpose, comprising the conductor 31 and the heater pipe 35. Although not shown, the heating units 30 shown in Fig. 5 also comprise the electric insulation 33 and advantageously the thermal insulation 37.
[0048] The conductor 31 extends through the bore of the heater pipe 35 and connects to an electric power supply 41. The power supply 41 can for instance be a frequency converter. In particular, the power supply 41 can be a frequency converter typically used for a variable frequency drive (VFD) (often referred to as a VSD - variable speed drive - which typically is used for controlling rotating machinery).
[0049] The conductor 31 has a conductor bore 32 that communicates with a cooling fluid supply 43. When used with the reactor assembly 1 shown in Fig. 1, the heating unit 30 will be located inside the vessel 3, while the power supply 41 and the cooling fluid supply 42 will be located outside the vessel 3. Hence, the conductor 31 can be extended through the wall 3a of the vessel 3 and thus constitute the power supply lines 11 shown in Fig. 1. The wall 3a of the vessel 3 is indicated with the dashed line in Fig. 5.
[0050] The heater pipes 35 shown in Fig. 5 are earthed at both ends to provide a path for the return current through the heater pipe 5.
[0051] Fig. 6 schematically illustrates an embodiment that is similar to the one shown in Fig. 5. However, instead of having one heating unit 30, the heater assembly 10 shown in Fig. 6 has four heating units 30. The four heating units 30 are connected to a common conductor 31 with a serial configuration. Although the heating units 30 are arranged with a serial configuration in Fig. 6, one may also arrange them with a parallel configuration.
[0052] The pipe ends of the heater pipes 35 are electrically interconnected and possibly earthed. Such interconnection can advantageously be done by connecting interconnecting cables 38 to the pipe connection flanges 39 (cf. Fig. 4) of the heater pipes 35.
[0053] Also shown in Fig. 6 are earthing cables 40 connected between earth and at least one of the heater pipes 35, at its respective pipe ends.
[0054] While the embodiments shown in Fig. 5 and Fig. 6 are shown with a cooling fluid supply 43 and thus a conductor 31 with a conductor bore 32, corresponding embodiments could be without the cooling fluid supply 43 and/or the conductor bore 32.
[0055] Fig. 7 depicts a heater assembly 10 configured for being powered with a three-phase power supply 41. The heater assembly 10 comprises two sets 45 of three heating unit groups 47, wherein each heating unit group 47 comprises four heating units 30. The embodiment shown in Fig. 6 thus comprises one group 47 having four heating units 30.
[0056] Similar to Fig. 6, adjacent heater pipes 35 are electrically interconnected with interconnection cables 38. Moreover, the heater pipes 35 are also connected to earth with earthing cables 40. It is noted that while in Fig. 7 only some of the heater pipes 35 (shown as heating units 30) are illustrated with interconnection cables 38 and earthing cables 40, they will typically all be interconnected and they may all be earthed.
[0057] The total number of heating units 30 shown in Fig. 7 is thus two sets x three groups x four heating units per group = 24 heating units 30.
[0058] The number of heating units 30 per heating unit group 47 can be different from four, for instance one, two, three or more than four. Moreover, the number of heating unit groups 47 in each set 45 can be different from three. Correspondingly, the number of sets 45 can be different from two.
[0059] However, as will become apparent with the following discussion, it is advantageous to have three heating unit groups 47 per set 45. It is also advantageous to have two sets 45.
[0060] The cooling fluid supply 43 has a return inlet 43a and a cooling outlet 43b. The cooling outlet 43b guides cooled fluid, typically a liquid such as water, and branches, at a branching point 44, into three conductors 31 with conductor bores 32. The three conductors 31 extend through the three heating unit groups 47 of a first set 45 and further through the three heating unit groups 47 of a second set 45. The three conductors 31 leaving the said second set 45 are joined, at a branching point 44, to the return inlet 43a. Thus, the cooling fluid, which now has been heated, is collected in the cooling fluid supply 43. In the cooling fluid supply 43, the cooling fluid is cooled before another run through the conductors 31.
[0061] The three-phase power supply 41 connects with three power supply lines 11 to the respective conductors 31 that extend between the two sets 45. The electric currents flowing through the respective three conductors 31 of the respective two sets 45 of three heating unit groups 45 flow to the return inlet 43a and to the cooling outlet 43b, respectively. Hence, the branching point 44 at return inlet 43a and the branching point 44 at cooling outlet 43b are electrical neutral points or star-points that can be earthed.
[0062] The power supply lines 11 from the power supply 41 connect to the conductors 31 at connection points 14. From the connection points 14, the conductors 31 extend into a respective proximate heating unit 30a of the respective heating unit groups 47. The proximate heating units 30a are the heating units of being most proximate to the power supply 41 (i.e. in electrical sense, not necessarily in a spatial sense). After a respective remote heating unit 30b of the respective heating unit groups 47, the conductors 31 are connected, as discussed above.
[0063] While the electric layout and the path of the cooling fluid appear from the schematic diagram of Fig. 7, Fig. 8 shows how the plurality of heating units 30 can be assembled inside the vessel 3. The heating units 30 are arranged with their radially outer surfaces of the heater pipes beside each other. The six heating unit groups 45 shown in Fig. 7 each have a stacked configuration, such as shown in Fig. 6. Moreover, the heating unit groups 47 are arranged next to each other. As a result, the cross-section shown in Fig. 8 depicts a 6 × 4 configuration of the heating units 30.
[0064] Fig. 9 depicts the same heating units 30 as in Fig. 8, however with a schematic side view. Also shown in Fig. 9 are baffles 61 interposed between the heating units 30 to direct the matter flowing through the vessel 3.
[0065] The length of the respective heating units 30, or the heater pipes 35, can typically be between 1 and 10 meters, for instance between 3 and 7 meters.
[0066] While the heating units 30 of the embodiment shown in Fig. 8 and Fig. 9 have a rectangular grid configuration, wherein the heating units 30 are arranged along straight rows and columns, other configurations are possible. However, for a 3-phase heater assembly 10, the number of heating units 30 should preferably be an even multiple of 3. This facilitates electric load symmetry and may further provide a fairly simple wiring or routing of the conductors 31 at the end portions of the reactor assembly 1. This will appear from the embodiment shown in Fig. 12, which will be discussed further below.
[0067] Fig. 10 depicts a schematic cross section view through another embodiment, having heating units 30 stacked within a vessel 3. 48 heating units 30 are arranged inside the vessel 3. The electric layout can for instance be similar to the layout shown in Fig. 7. For instance, the heater assembly 10 may comprise four sets 45 of three heating unit groups 47, wherein each heating unit group 47 comprises four heating units 30.
[0068] In the embodiment shown in Fig. 11, another electric layout is disclosed. In this embodiment, the power supply 41 is connected to a transformer 50. The transformer 50 has three primary windings 51 and three secondary windings 53. The primary and secondary windings 51, 53 are arranged inside a transformer enclosure 55 and the transformer has a Dyn configuration.
[0069] As the skilled reader will appreciate, electric power is in this embodiment transferred to the heating units 30 through the transformer 50. There is no direct electrical contact between the power supply 41 and the return inlet 43a, the cooling outlet 43b, and the conductors 31.
[0070] A cooling fluid pump 46 is arranged to pump cooling fluid through the conductor bores 32 (cf. Fig. 3) of the conductors 31.
[0071] Fig. 12 depicts an embodiment that in many respects is similar to the embodiment shown in Fig. 11. However, the electric power is not transferred via the transformer 50. Instead, phase cells 41a of the power supply 41, which in the present embodiment is a frequency converter, are connected directly to the conductors 31 of three phases of the heater assembly 10. The frequency converter (power supply 41) as such is not shown in Fig. 12, beyond its phase cells 41a.
[0072] It shall be understood that the examples shown in and discussed with reference to Fig. 5 to Fig. 12 above are merely schematic / principle examples. For instance, the skilled reader will appreciate that a conductor 31 extending between two heating units 30 may be covered with an electric insulation 33 and possibly also a thermal insulation 37, although not shown in the drawings.
[0073] Fig. 13 depicts a further embodiment of a reactor assembly 1 according to the invention. When the reactor assembly 1 is used to treat matter, for instance a gas, at high temperatures, one must prevent that the conductors 31 and the lines that convey the cooling fluid are not excessively heated.
[0074] This is solved with the embodiment shown in Fig. 13. The reaction chamber 5 is delimited in part by a first and second thermal insulation wall 3b, 3c. A plurality of conductors 31 extend through the first thermal insulation wall 3b. The power supply 41 connects to the conductors 31 at the external side of the first thermal insulation wall 3b. Moreover, the (not shown) cooling fluid supply also connects to the conductors 31 at the external side of the thermal insulation wall 3b. As the skilled reader will appreciate, the connection of the power supply 41 and the cooling fluid supply 43 resembles the embodiment shown in Fig. 7.
[0075] The conductors 31 exit the reaction chamber 5 through the second thermal insulation wall 3c to make a turn for re-entry through the same wall.
[0076] While not compulsory, it is advantageous to support the heater pipes 35 with the first and second thermal insulation walls 3b, 3c. In such embodiments, the conductors 31 need not be exposed to the pressure inside the reaction chamber 5, as the heater pipes 35 can be made to withstand the pressure drop over their pipe walls.
[0077] The reactor assembly 1 disclosed in Fig. 13 comprises a first and a second buffer chamber 63a, 63b. The first buffer chamber 63a is adjacent the first thermal insulation wall 3b, while the second buffer chamber 63b is adjacent the second thermal insulation wall 3c.
[0078] Advantageously, the first and second buffer chambers 63a, 63b can be pressurized, such that the pressure drop over the first and second thermal insulation walls 3b, 3c is reduced.
[0079] As an example, the pressure of the matter entering the inlet 7 can be 24 bar and the pressure of the matter exiting through the outlet 9 can be 20 bar. Advantageously, the pressures in the first and second buffer chambers 63a, 63b can be above the ambient pressure, however below the pressure within the reactor chamber 5. In this embodiment, the pressure inside the first and second buffer chambers 63a, 63b can thus be for instance 19 bar.
[0080] To provide the desired pressure inside the first and second buffer chambers 63a, 63b, there is arranged a pressure control unit 64, which is configured to adjust the pressure.
[0081] Moreover, also merely serving as an example, the matter introduced through the inlet 7 can for instance be at a temperature below 600 °C or 700 °C, while the matter exiting the vessel 3 through the outlet 9 can be at a temperature between 1100 °C and 1300 °C, for instance 1200 °C.
[0082] Also schematically shown in Fig. 13 is a buffer gas circulation system 70. The buffer gas circulation system 70 is configured to insert buffer gas into the first buffer chamber 63a and receive buffer gas that exits the second buffer chamber 63b. The buffer gas flows from the first buffer chamber 63a to the second buffer chamber 63b through the heating units 30. In particular, the buffer gas flows through the first gap 34 or annulus arranged radially outside the conductor 31 (cf. Fig. 4). This first gap 34 can be between the electric insulation 33 and the bore of the thermal insulation 37. However, it may also be said to be outside the conductor 31, as not all embodiments may have the thermal insulation 37 in addition to the electric insulation 33.
[0084] The buffer gas can thus be used to cool down the conductor 31. To this end the buffer gas circulation system 70 comprises a buffer gas cooler 71. The buffer gas cooler 71 will cool down the buffer gas, which will have been heated by the flow through the heating units 30.
[0085] To provide the circulation of the buffer gas, the buffer gas circulation system 70 comprises a buffer gas pump 73.
[0086] Preferably, the buffer gas circulation system 70 may also comprise a buffer gas analyzer unit 75. The buffer gas analyzer unit 75 is configured to measure the contents of the buffer gas. The buffer gas can preferably comprise an idle gas, such that it does not react with the components within the heating units 30. The buffer gas analyzer unit 75 is configured to detect presence of reaction gases, i.e. gases that will be present outside the heating units 30 and inside the reactor chamber 5. Detection of the presence of such a gas mixed into the buffer gas will imply a leak.
[0087] The first buffer chamber 63a comprises buffer chamber access apertures 65 for receiving cooling fluid, power supply lines 11, and buffer gas. Similarly, the second buffer chamber 63b has a buffer chamber access aperture 65 to enable exit of the buffer gas. The skilled reader will appreciate that while Fig. 13 is a schematic illustration, the said buffer chamber access apertures 65 are configured such as to maintain the previously discussed pressure inside the first and second buffer chambers 63a, 63b.
[0088] For embodiments of the heater assembly 10 and/or the reactor assembly 1 intended for particularly high temperatures, for instance above 1000 °C, the heater pipes 35 can advantageously comprise cobalt. Cobalt has a Curie temperature of about 1130 °C. In some embodiments, the heater pipes 35 may comprise a cladding comprising cobalt, while in other embodiments, the heater pipes 35 may be made of cobalt or an alloy comprising cobalt. The use of cobalt in the heater pipe material contributes to maintaining the ferromagnetic properties of the material at higher temperatures. This provides better magnetic coupling and thus a more efficient heater assembly 10.
1. A heater assembly (10) comprising a plurality of heating units (30), wherein the heating
units comprise
- a heater pipe (35);
- a conductor (31) inside the heater pipe for conveying electric current;
- electric insulation (33) arranged between the conductor and the heater pipe to electrically insulate the conductor;
wherein the heating units (30) are arranged with their radially outer surfaces of the heater pipes (35) beside each other.2. A heater assembly (10) according to claim 1, wherein the conductor (31) comprises
a conductor bore (32) for conveying a cooling fluid.
3. A heater assembly (10) according to claim 1 or claim 2,
- wherein it comprises one or more sets (45) of three heating unit groups (47);
- wherein the respective one of the three heating unit groups (47) connects to one of respective three power supply lines (11) configured for connection to a three-phase power supply (41);
- wherein the respective heating unit groups (47) comprises a plurality of heating units (30), including a proximate heating unit (30a) and a remote heating unit (30b);
- wherein the conductors (31) exiting the respective remote heating units (30b) of the respective heating unit groups (47) of a common set (45) connect to each other at a branching point (44).
4. A heater assembly (10) according to claim 2 and claim 3, wherein it comprises two
sets (45) of three heating unit groups (47), wherein a return inlet (43a) and a cooling
outlet (43b) of a cooling fluid supply (43) connect to a respective branching point
(44) of the respective two sets (45) of three heating unit groups (47).
5. A heater assembly (10) according to one of the preceding claims, wherein it comprises
- a three-phase power supply (41),
- a transformer (50) with primary windings (51) and secondary windings (53), wherein the primary windings connect to the power supply (41) and the secondary windings (53) connect to the conductors (31) of the heating units (30),
- a cooling fluid supply (43) with a cooling outlet (43b) and a return inlet (43a) connected to respective cooling lines (43c) that connect to conductors (31) on opposite sides of the plurality of heating units (30) to form a cooling loop, as the conductors (31) comprise conductor bores (32) for conveying cooling fluid, and
- a cooling fluid pump (46).
6. A heater assembly (10) according to one of claims 1 to 5, wherein it comprises a power
supply (41) in the form of a frequency converter comprising phase cells (41a), wherein
the phase cells (41a) connect to a respective power line (11) that connect to a respective
conductor (31).
7. A heater assembly (10) according to one of the preceding claims, wherein the heater
pipe (35) comprises cobalt.
8. A reactor assembly (1) comprising a vessel (3) with a reactor chamber (5) and a heater
assembly (10) according to one of the preceding claims, wherein the vessel (3) comprises
an inlet (7) and an outlet (9), and wherein the heating units (30) are arranged inside
the vessel (3).
9. A reactor assembly (1) according to claim 8, wherein the vessel (3) comprises a first
and a second thermal insulation wall (3b, 3c) arranged at the respective ends of the
heating units (30), to form a fluid barrier between the interior of the vessel (3)
and a gap (34) located between the conductor (31) and the inner surface of the heater
pipe (35).
10. A reactor assembly (1) according to claim 9, wherein it further comprises a first
buffer chamber (63a) adjacent the first thermal insulation wall (3b) and a second
buffer chamber (63b) adjacent the second thermal insultation wall (3c), such that
conductors (31) extending out from the heating units (30) extend into the first and
second buffer chambers (63a, 63b).
11. A reactor assembly (1) according to claim 10, wherein it further comprises a pressure
control unit (64) configured to control the pressure in the first and second buffer
chambers (63a, 63b).
12. A reactor assembly (1) according to claim 10 or claim 11, wherein it further comprises
a buffer gas circulation system (70) configured to circulate buffer gas between the
first and second buffer chambers (63a, 63b), through the heating units (30), wherein
the buffer gas circulation system (70) comprises a buffer gas cooler (71), a buffer
gas pump (73), and a buffer gas line (72) extending between the first and second buffer
chambers (63a, 63b).
13. Use of a reactor assembly according to one of claims 8 to 12 to
- produce iron in a direct reduced iron process; or
- produce carbon black; or
- produce methanol from syngas.