Patent Application
20160209115
The invention relates to an oxidation furnace for the oxidative treatment of fibres, in particular for the production of carbon fibres, having
In such oxidation furnaces, the deflecting regions are typically sited outside the furnace housing in order on the one hand to permit intervention on the fibre and on the other hand to prevent inadequate aeration upon deflection at the process temperature. By arranging the deflecting rollers outside the furnace, the fibre is guided at the process temperature out of the process chamber through a lock region in the direction towards the deflecting roller. In the lock region, the fibre is cooled in order to stop the oxidation reaction, the temperature in the lock region being so chosen that gaseous substances from the atmosphere are prevented from condensing out. When the fibre leaves the furnace, the fibre accordingly at least has the temperature prevailing in the lock region. At least some of this heat energy is dissipated to the surrounding atmosphere on the path to the deflecting roller, during deflection and on the path back towards the furnace, or in the case of contact with the deflecting roller to the deflecting roller itself. The fibre accordingly passes through the lock again into the furnace with a significantly lower temperature and must be heated to the process temperature again. The energy loss thus caused by cooling is considerable. It is accordingly constructive to prevent the thread from cooling or deliberately to induce cooling in such a manner that the energy that is released can be fed back to the system again.
During operation of an oxidation furnace, work must be carried out in particular in the deflecting regions and at the deflecting rollers. For example, the fibre carpet may have to be straightened at a deflecting roller if fibres run off track. Individual fibres can also tear as they pass through the oxidation furnace. The loose end of a torn fibre is conventionally linked in the region of the deflecting rollers to an adjacent fibre, which then carries the torn fibre through the oxidation furnace. When carrying out such activities it is consequently beneficial to achieve low temperatures of the fibres in the deflecting region and further to keep the ambient temperature in the region of the deflections low, that is to say only slightly above ambient temperature.
Accordingly, the object of the invention is to provide an oxidation furnace of the type mentioned at the beginning which takes account of these ideas.
The object is achieved in an oxidation furnace of the type mentioned at the beginning in that
In this manner it is ensured that the mentioned work in the deflecting region can be carried out at moderate temperatures in the region of the deflecting rollers and at the deflecting rollers themselves, which significantly simplifies continuous operation of the oxidation furnace.
It is advantageous if the outgoing fibres can be exposed by means of the fibre cooling device to a cooling gas which has a lower temperature than the outgoing fibres. There is used as the cooling gas preferably hall air from the equipment hall in which the oxidation furnace is situated.
To that end, the fibre cooling device advantageously comprises an intake system with which a cooling gas can so be taken in that it flows to the outgoing fibre carpets. In the case of hall air, air is consequently taken in from the deflecting regions.
In order to ensure that the cooling gas reaches the outgoing fibres, it is advantageous if the intake system comprises a plurality of intake devices each having a suction side with at least one intake opening, wherein at least one intake device faces each outgoing fibre carpet. Air from the deflecting regions, for example, can thus be taken in through the outgoing fibre carpets to the intake devices and from there can be conveyed away.
In addition, it can be advantageous if the intake system for each outgoing fibre carpet comprises at least one intake device above and at least one intake device below a common outgoing fibre carpet, wherein the suction sides thereof are in each case opposite one another and face the common outgoing fibre carpet. This is advantageous in particular when the outgoing fibres form a closed fibre carpet through which the cooling gas cannot readily flow. However, the cooling gas is thus able to flow along the outgoing fibre carpets.
From a technical point of view, it is advantageous if the intake devices are in the form of intake boxes which are connected by way of one or more intake lines to one or more negative pressure sources.
The fibre cooling device has been found to be particularly efficient in the case of oxidation furnaces in which the deflecting regions are situated outside the furnace housing, the intake devices being arranged in the deflecting regions.
If a conveyor system is present, by means of which cooling gas which has been taken in and heated by the outgoing fibres can be transported away and fed to a further use, the heat energy which has been transmitted from the outgoing fibres to the cooling gas can be used effectively.
For the operation of the oxidation furnace itself, it is particularly energy efficient if cooling gas which has been taken in and heated by the outgoing fibres can be conveyed to the atmosphere device. In this manner, the heated cooling gas can contribute towards the gas balance of the oxidation furnace and in particular towards maintaining the operating temperature.
If the atmosphere device comprises at least one heating unit, it is advantageous if cooling gas which has been taken in and heated by the outgoing fibres can be fed thereto as combustion air.
As an alternative or in addition to the intake system, it is advantageous if the fibre cooling device comprises a blowing system with which outgoing fibres can purposively be blown with cooling gas.
To that end, the blowing system advantageously comprises a plurality of blowing devices each having a blowing side with at least one blowing opening, wherein at least one blowing device faces each outgoing fibre carpet.
Especially in the case of dense outgoing fibre carpets, it is advantageous if the blowing system for each outgoing fibre carpet comprises at least one blowing device above and at least one blowing device below a common outgoing fibre carpet, wherein the blowing sides thereof are in each case opposite one another and face the common outgoing fibre carpet.
The blowing devices are preferably in the form of blowing boxes which are connected by way of one or more blowing lines to a cooling gas source.
The blowing devices can cooperate with the intake devices so that blown cooling air which has been heated by the fibres is conveyed away by the intake system. This will become clear from the explanations given below.
Embodiments of the invention will be described in greater detail below with reference to the drawings, in which:
Reference will first be made to
The oxidation furnace 10 comprises a housing 12 which delimits a passage chamber 14, which forms the interior of the oxidation furnace 10, by means of a top wall 12a and a bottom wall 12b and two vertical longitudinal walls, of which only a longitudinal wall 12c lying behind the section plane can be seen in
At each of its ends the housing 12 has an end wall 16a, 16b, wherein horizontal inlet slots 18 and outlet slots 20 alternating from top to bottom are present in the end wall 16a and horizontal outlet slots 20 and inlet slots 18 alternating from top to bottom are present in the end wall 16b, through which slots the fibres 22 are guided into and out of the passage chamber 14. The inlet and outlet slots 20 generally form passage regions of the housing 12 for the carbon fibres 22. Apart from these passage regions, the housing 12 of the oxidation furnace 10 is gas-tight.
The passage chamber 14 is in turn divided into three regions in the longitudinal direction and comprises a first prechamber 24, which is arranged directly adjacent to the end wall 16a, a second prechamber 26, which is directly adjacent to the opposite end wall 16b, and a process chamber 28 sited between the prechambers 24, 26.
The prechambers 24 and 26 thus together form an inlet and outlet lock for the fibres 22 into the passage chamber 14 or the process chamber 28.
The fibres 22 to be treated are fed to the passage chamber 14 of the oxidation furnace 10 in parallel as a kind of fibre carpet 22a. To that end, the fibres 22 pass from a first deflecting region 30, which is situated adjacent to the end wall 16a outside the furnace housing 12, through the topmost inlet slot 18 in the end wall 16a into the first prechamber 24. The fibres 22 are then guided through the process chamber 28 and through the second prechamber 26 to a second deflecting region 32, which is situated adjacent to the end wall 16b outside the furnace housing 12, and back from there again.
Overall, the fibres 22 pass through the process chamber 28 in a serpentine manner by way of deflecting rollers 34 arranged in succession from top to bottom, which deflecting rollers are designated 34a, 34b, 34c, 34d, 34e, 34f following the path of the fibres from bottom to top. Three deflecting rollers 34a, 34c, 34e lying with their axes parallel one above the other are arranged in the second deflecting region 32 of the oxidation furnace 10, and three such deflecting rollers 34b, 34d, 34f are provided in the first deflecting region 30. Between the deflecting rollers 32a, 32b, 32c, 32d, 32e, 32f, the fibre carpet formed by the plurality of fibres 22 running side by side spans a plane. The path of the fibres can also be from bottom to top. It is also possible for more or fewer planes than shown in
This is illustrated in
During operation of the oxidation furnace 10, the deflecting regions 30, 32 are continuously in contact with the area surrounding the oxidation furnace 10.
After passing through the entire process chamber 28, the fibres 22 leave the oxidation furnace 10 through the bottommost outlet slot 20 in the end wall 16b. Before they reach the topmost inlet slot 18 in the end wall 16a and after they leave the oxidation furnace through the bottommost outlet slot 20 in the end wall 16b, the fibres 22 are guided over further guide rollers 36 outside the furnace housing 12.
In the process chamber 28, two opposing air streams are maintained. To that end, a blowing-in device 38 is arranged in the middle region of the process chamber 28, and an exhaust device 40 is arranged in each of the two outer end regions of the process chamber 28, adjacent to the prechambers 24, 26. The blowing-in device 38 comprises a plurality of blowing-in boxes 42 and the exhaust devices 40 comprise a plurality of exhaust boxes 44 which are each arranged between the planes spanned by the fibre carpet 22a and extend between the vertical longitudinal walls of the furnace housing 12.
Starting, for example, from the exhaust devices 40, the air is conveyed into an air guiding chamber 46 which is situated behind the plane of projection in
From the air guiding chamber 46, the air passes to the blowing-in device 38. This delivers the circulated and conditioned air into the process chamber 28 in such a manner that it flows in opposite directions towards the deflecting regions 30 and 32. In the process chamber, the air streams flow in opposite directions to the exhaust devices 40, which is illustrated in
The blowing-in device 38 and the exhaust devices 40 accordingly form, together with the air guiding chamber 46 and conditioning devices which are present, an atmosphere device with which hot air can be generated as the hot working atmosphere and blown into the process chamber 28.
As the fibres 22 pass in a serpentine manner through the process chamber 28, hot, oxygen-containing air thus flows around them and they are thereby oxidised. The precise configuration both of the blowing-in device 38 and of the exhaust devices 40 and the flow path of the air from the blowing-in device 38 to the exhaust devices 40 are of no further importance in the present document.
Two outlets 48 are additionally provided in the region of the air guiding chamber 46. The gas or air volumes which are either formed in the oxidation process or enter the process chamber 28 as fresh air through an air inlet device (not shown) can be removed via these outlets, in order thus to maintain the air balance in the oxidation furnace 10. The gases which are removed, which may also contain toxic constituents, are fed to thermal post-combustion. The heat which may thereby be recovered can be used at least for preheating the fresh air fed to the oxidation furnace 10.
The fibres 22 which have left the process chamber 28 and are on the path to a deflecting roller 34 are referred to hereinbelow as outgoing fibres 50, which form an outgoing fibre carpet 50a. Outgoing fibres 50 are accordingly both fibres 22 which are still in the passage chamber 14 and fibres 22 which have already passed through the outlet slots 20 out of the passage chamber 14 into the deflecting regions 30, 32 and are situated in the deflecting regions 30, 32.
Correspondingly, the fibres 22 which, coming from a deflecting roller 34, are on the path back into the passage chamber 14 and the process chamber 28 again define incoming fibres 52 and form an incoming fibre carpet 52a, this being the fibres 22 in the portion of the fibre carpet 22 from the deflecting rollers 34 to the process chamber 28.
In order that maintenance operations discussed at the beginning in the region of the deflecting rollers 34 can be carried out safely, the oxidation furnace 10 comprises a fibre cooling device 54 by means of which the outgoing fibres 50 can purposively be cooled before they reach the deflecting rollers 34. To that end, the outgoing fibres 50 are exposed to a cooling gas which has a lower temperature than the outgoing fibres 50.
The fibre cooling device 54 shown in
The intake boxes 56 preferably have a rectangular cross-section and extend parallel to the adjacent deflecting roller 34. On the suction side facing the outgoing fibre carpet 50a, the intake boxes 56 have a plurality of intake openings 58, which are distributed over the whole of the suction side. The intake boxes 56 are intake devices of an intake system 60 with which a cooling gas is taken in from the deflecting regions 30 and 32. The cooling gas is generally fresh air, which is available through the hall air of the equipment hall in which the oxidation furnace 10 is situated. That air then flows through the outgoing fibre carpets 50a, so that the outgoing fibres 50 are exposed to that air as cooling gas.
To that end, the intake boxes 56 are connected by way of an intake line 62 to a negative pressure source in the form of a fan 64, which operates as an induced draught fan relative to the intake boxes 56. When the oxidation furnace 10 is in operation, the induced draught fan 64 is activated, the air taken in flows through the outgoing fibre carpets 50a and thereby takes up heat energy from the outgoing fibres 50, which thereby cool. Before the outgoing fibres 50 reach the deflecting rollers 34, they can thus be cooled considerably relative to their outlet temperature at which they leave the passage chamber 14. For example, the outgoing fibres 50 can be cooled to temperatures of 60° C.
Despite the oxidative reaction being interrupted in the prechambers 24, 26 by the temperature reduction, the outgoing fibres 50 may still emit gases in the deflecting regions 30, 32, whereby HCN inter alia can be released and, without further measures, enters the hall atmosphere. These gas emissions are removed by the intake boxes 56, so that the workplace concentrations are additionally reduced by the gas emissions.
The fibre cooling device 54 is additionally connected to a conveyor system 66 with which the cooling gas, in the present case air, which has been taken in and heated can be transported away and fed to a further use. The heat energy of the heated air can be used in another location, for example, and fed to a heat exchanger for that purpose.
The heated air from the fibre cooling device 54 contributes towards the air balance of the oxidation furnace 10 itself. To that end, the air is fed, for example, via the conveyor system 66 to a fresh air conditioning system 69, which is additionally illustrated in
In this embodiment, the fibre cooling device 54 additionally comprises a blowing system 70 with which the outgoing fibres 50 can purposively be blown with cooling gas. To that end, a plurality of blowing boxes 72 are present as blowing devices, which blowing boxes correspond in their basic construction to the intake boxes 56 of the intake system 60 and have blowing openings 74 on a blowing side. Only the topmost blowing box 72 is provided with a reference numeral.
In a first variant, the blowing boxes 72 are arranged above the outgoing fibre carpets 50a and in each case opposite an intake box 56, the blowing openings 74 of a blowing box 72 facing the intake openings 58 of an intake box 56. This is the case in
In a second variant, the blowing boxes 72 are arranged beneath the outgoing fibre carpets 50a and in each case opposite an intake box 56, the intake boxes in this case being situated above the respective outgoing fibre carpet 50a. Here too, the blowing openings 74 of a blowing box 72 and the intake openings 58 of an intake box 56 face an outgoing fibre carpet 50a running between them and one another. This variant is realised in
The flow path 76 between the blowing boxes 72 and the intake boxes 56 is illustrated in
The blowing boxes 72 are supplied with a cooling gas by way of a blowing line 78 by means of a fan 80 serving as the cooling gas source. The cooling gas can be fresh air and, for example, again the hall air. Alternatively, however, cooling gas other than air can also be provided in this manner.
If this cooling gas is not to enter the furnace atmosphere, the conveyor system 66 can also convey the heated cooling gas to another location, where its heat can be used.
In this embodiment there is no blowing system 70, but for each outgoing fibre carpet 50a an intake box 56 is provided above and an intake box 56 is provided below the outgoing fibre carpet 50a, the suction sides thereof in each case being opposite one another and facing the common outgoing fibre carpet 50a. The intake openings 58 are not distributed over the whole of the suction side but are present only in the edge regions facing the end walls 16a, 16b of the oxidation furnace 10.
There is thus formed between the intake boxes 56 a flow channel 82 in which a respective outgoing fibre carpet 50a runs. When the induced draught fan 64 is activated, air from outside is drawn as cooling gas through the flow channel 82 between two suction boxes 56, where it is able to flow along above and below the outgoing fibre carpet 50a until it reaches the intake openings 58 of the intake boxes 56.
This variant can be used in particular when the fibres 22 form cohesive and closed fibre carpets 22a in which a through-flow is difficult. Cooling gas reaches such closed fibre carpets 22a on both sides in this manner.
In this embodiment, both intake boxes 56 and blowing boxes 72 are arranged above and below the outgoing fibre carpets 50a. Adjacent to the end wall 16a or 16b of the oxidation furnace 10 there are intake boxes 56, the suction sides of two intake boxes 56 being opposite one another and facing a common outgoing fibre carpet 50a. The intake openings 58 are again present in the edge regions of the intake boxes 56 that face the end walls 16a, 16b of the oxidation furnace 10.
On the side of the intake boxes 56 that is remote from the end walls 16a, 16b there are arranged blowing boxes 72, the blowing sides of two blowing boxes 72 correspondingly being opposite one another and facing a common outgoing fibre carpet 50a. The blowing openings 74 are arranged in the edge regions of the blowing boxes 72 that are remote from the end walls 16a, 16b of the oxidation furnace 10 and the intake boxes 56.
A flow channel 82 is again formed in each case between the intake boxes 56 and the blowing boxes 72. The cooling gas from the blowing boxes 72 flows into the flow channel 82 from the top and bottom, relative to the outgoing fibre carpet 50a, and along the top and bottom side of the respective outgoing fibre carpet 50a, so that the outgoing fibres 50 cool down and the cooling gas is heated and then conveyed away via the intake boxes 56.
At the same time, hall air is drawn into the flow channel 82 on the side of the flow channel 82 that is remote from the end walls 16a, 16b, which hall air contributes towards cooling the outgoing fibres 50a.
The protective device 84 comprises a plurality of protective plates 86, which in the present embodiment have a C-shaped cross-section, only the topmost protective plate 86 bearing a reference numeral. The protective plates 86 are each situated between an outgoing fibre carpet 50a and an incoming fibre carpet 52a adjacent to a deflecting roller 34, the open side of the “C” facing the deflecting roller 34. A protective space is thereby formed on the rear side of the deflecting roller 34.
By means of the protective device 84, the risk of the moved and deflected fibres 22 being caught during work on the rear side of the deflecting rollers 34 is reduced. The protective device 84 can also be so designed that the protective plates 86 is designed functionally as part of the intake boxes 56 and blowing boxes 72.
In the embodiments of the fibre cooling device 54 discussed above, there are two principles of operation. On the one hand, the fibre cooling device 54 can be in the form of a passive system in terms of the cooling gas. This means that the cooling gas is available from the surroundings. This is the case in the embodiments in which only an intake system 60 is present.
On the other hand, the fibre cooling device 54 can be in the form of an active system in terms of the cooling gas. This means that the cooling gas is actively supplied from a source. This is the case in the embodiments in which the blowing system 70 is also present.
In modifications (not shown), the fibre cooling device 54 can also operate in the passage chamber 14. For example, the intake boxes 56 can be formed by the exhaust boxes 44 in the passage chamber 14 of the oxidation furnace 10. The outgoing fibre carpets 50a are not actively exposed to cooling gas and run either between the closed rear sides of fresh air channels, as are designated 71 in
The intake boxes 56 in the form of the exhaust boxes 44 take in the atmosphere from the prechambers 24, 26, so that air from outside is taken in through inlet slots and then flows in the mentioned flow channel along the outgoing fibre carpets 50a, cools them and thereby takes up heat energy. From the exhaust boxes 44, that air then passes into the air guiding chamber 46 and back into the process chamber, so that its heat energy contributes to the air balance of the oxidation furnace 10.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2013 015 841.9 | Sep 2013 | DE | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2014/002517 | 9/17/2014 | WO | 00 |
