BRIEF DESCRIPTION OF THE DRAWINGS
The present invention is further described in the detailed description which follows, in reference to the noted plurality of drawings by way of non-limiting examples of exemplary embodiments of the present invention, in which like reference numerals represent similar parts throughout the several views of the drawings, and wherein:
FIG. 1 shows a drying device combined with a fuel cell unit for a machine according to the first embodiment of the present invention,
FIG. 2 shows a drying device for a machine according to the second embodiment of the present invention,
FIG. 3 shows a further exemplary embodiments of drying devices for a machine according to the invention, and
FIG. 4 shows a further exemplary embodiments of drying devices for a machine according to the invention.
DETAILED DESCRIPTION OF THE PRESENT INVENTION
The particulars shown herein are by way of example and for purposes of illustrative discussion of the embodiments of the present invention only and are presented in the cause of providing what is believed to be the most useful and readily understood description of the principles and conceptual aspects of the present invention. In this regard, no attempt is made to show structural details of the present invention in more detail than is necessary for the fundamental understanding of the present invention, the description taken with the drawings making apparent to those skilled in the art how the several forms of the present invention may be embodied in practice.
FIG. 1 shows a drying device, designated generally by 10, for a paper machine according to the first embodiment of the present invention. The drying device 10 comprises an arrangement of drying cylinders 12 in two mutually parallel rows. Around the drying cylinders 12 of a row, with the aid of felt guide rolls 14, a dryer felt 16 is guided in such a way that it runs around approximately two thirds of each drying cylinder 12 and is subsequently guided around a felt dryer 18. A material web section 20 to be dried enters the drying device 10 on the side of the latter on the left in FIG. 1, in that it runs between the dryer felt 16 of the first row and the first drying cylinder 12 of the first row. After that, the material web section 20 runs around a first drying cylinder 12 of the second row, once more enclosed between the drying cylinder 12 on one side and a second dryer felt 16 of the second row on the other side. In this way, the material web section 20 to be dried runs alternately around the drying cylinders of the first and second row and, in the process, is in each case pressed by the corresponding dryer felt 16 against the circumferential surface of the drying cylinders 12, by which means the dryer felt 16 extracts moisture from the material web 20. The dryer felt 16 is for its part dried in a felt dryer 18 during its return run.
To increase the drying capacity of drying devices with drying cylinders, it is known to heat the drying cylinders. In the drying device 10 of the first embodiment of the present invention, each drying cylinder 12 is connected to a feed duct 22, via which a heating medium can be supplied to the respective drying cylinder 12. According to FIG. 1, a feed duct 22 is provided for each row of drying cylinders 12 in each case, the two feed ducts 22 being connected to a main feed line 24 which, in turn, is connected to a fuel cell unit 26.
In the example shown in FIG. 1, the main feed line 24 is charged with the waste air from the fuel cell unit 24, which then flows into the feed ducts 22 at a temperature of several hundred degrees Celsius and is led directly from there into the individual drying cylinders 12. There, the waste air supplied gives up part of its thermal energy to the drying cylinders 12, for example to their walls, which means that the drying cylinders 12 are heated to a specific temperature or kept at a specific temperature. After the waste air has given up at least part of its thermal energy to the drying cylinders 12, it flows out of the drying cylinders 12 through openings, not shown, and can then be led away or else reused.
In addition to the example shown in FIG. 1 with direct supply of the waste air from the fuel cell unit 26 to the drying cylinders 12, however, it is also conceivable to use a heat exchanger, whose primary side is heated by the hot waste air and whose secondary side is in thermal contact with the drying cylinders 12 via a heat transfer medium, in order to transfer the thermal energy from the waste air to the drying cylinders 12. It is then also conceivable likewise to provide any electrical energy which may possibly be needed to drive pumps, motors or the like for moving the waste air or the heat transfer medium by means of the fuel cell unit 26.
In connection with the invention, use can advantageously be made of a fuel cell unit having a high temperature fuel cell, whose operating temperature lies in the range from about 600° C. to about 1000° C., so that the waste air discharged by the fuel cell has a temperature from about 300° C. to about 600° C. An example of such a fuel cell unit 26, illustrated schematically in FIG. 1, comprises a gas preparation unit 28, a central unit 30 with fuel cell stacks 32 arranged therein and an electrical unit 34 having an energy conditioning unit 36 and a control/regulating unit 38. The gas preparation unit is supplied with fresh air via a fresh air inlet 40 and with natural gas, town gas or another suitable fuel gas via a gas inlet 42. The gas supplied via the gas inlet 42 is prepared in the gas preparation unit, in particular desulfurized and preheated, and subsequently supplied to the central unit 30 as process gas via a gas line 44. At the same time, the central unit 30 is supplied via a fresh air line 46 with the fresh air supplied to the gas preparation unit 28 via the fresh air inlet 40. In the central unit, process gas and atmospheric oxygen react at the electrodes of the fuel cell stack 32, forming electric charges and thermal energy.
The thermal energy produced is led out of the central unit 30 in the form of hot waste air and, via a waste air line 48, passes back to the gas preparation unit 28, from which it emerges through a waste air outlet 50. Depending on whether part of the thermal energy of the hot waste air is used in the gas preparation unit 28 for preheating fuel gas, the waste air leaves the fuel cell unit 26 at a temperature of about 400° C. or, respectively, at a temperature of about 600° C.
The charges produced on the electrodes of the fuel cell during the combustion process are led away via a power line 43 and provided to the energy conditioning unit 36 of the electrical unit 34. The energy conditioning unit 36 can convert the direct current supplied by the fuel cell into an alternating current if required, which can ultimately be used by a load. The operation of the fuel cell unit 26 is controlled and monitored by a control/regulating unit 38 which, for this purpose, is connected to the central unit 30 and the gas preparation unit 28 via lines 45 and 39, respectively.
In FIG. 2, a hot gas drying device 100 for a machine according to the second embodiment of the present invention is illustrated. The hot gas drying device 100 comprises two blower units 152, to which hot waste air from a fuel cell unit 126, indicated only schematically, can in each case be supplied via hot gas connections 154, and air can be supplied via fresh air connections 156. In the blower units 152, the air is brought into thermal contact with the hot waste gas via a heat exchanger and heated up to an operating temperature. The heated air then flows out of nozzles 158 into the blower units 152 as drying gas and acts on a material web 120 guided through between the blower units 152. The drying of the material web 120 is thus carried out without contact in a stream of hot drying gas, using the thermal energy provided by the fuel cell unit 126. After at least part of the thermal energy of the waste air has been transferred to the air supplied, cooled waste air leaves the blower unit 152 via outlets 160.
It should be mentioned that the blower units 152 can also be formed in such a way that the fresh air supplied is mixed in the blower units 152 with the waste air supplied from the fuel cell unit, and the gas mixture produced in this way leaves the blower units 152 through the nozzles 158 as drying gas in order to act on the material web 120. In addition, it would be conceivable to dispense entirely with a fresh air feed line and to arrange for the waste air from the fuel cell unit 126 to emerge directly from the nozzles 158 of the blower units 152 in order to dry the material web 120 directly in the stream of hot waste air.
FIG. 3 illustrates an exemplary embodiment of the present invention, in which an infrared drying device 200 for a machine, for example a paper machine, is connected to the waste air outlet 250 of a fuel cell unit 226, merely indicated in FIG. 3. The infrared drying unit 200 comprises two infrared radiant heaters 252 having radiant surfaces 258 which face a material web 220 to be dried guided through between the infrared radiant heaters 252.
Via hot gas connections 254, the infrared radiant heaters 252 are supplied with hot waste air from the fuel cell unit 226, which then gives up part of its thermal energy to the infrared radiant heaters 252 and then leaves the infrared radiant heaters 252 via outlets 260. The waste air from the fuel cell unit 226 is thus brought into thermal contact with the infrared radiant heaters 252 in order to heat up the radiant surfaces 258 of the infrared radiant heaters 252 to an operating temperature. The radiant surfaces 258 then emit thermal radiation in the direction of the material web 220 to be dried, by which means the latter is heated and dried. A further example of a drying device for a machine according to the present invention is shown by FIG. 4. In the drying device 300, a blower unit 352 is supplied via a hot gas connection 354 with hot waste air from a fuel cell unit 326, which, in a manner analogous to the drying device 100 of FIG. 2, heats fresh air there, which has been supplied to the blower unit 352 via a fresh air connection 356. The fresh air thus heated to an operating temperature then flows out of the blower unit 352 through nozzles 358 and acts on a material web 320 guided past the blower unit 352. Cooled waste air leaves the blower unit 352 via an outlet 360.
As opposed to the drying device 100 of FIG. 2, the surface 362 facing the material web 320, in which surface the nozzles 358 are also arranged, has a convex curvature, so that the running path of the material web 320 exhibits a curvature in this region. In this region, the material web 320 runs on an air bed, which is formed by the hot drying gas emerging from the nozzles 358. This principle relating to deflecting a moving material web is known as an airturn. In that, now, according to the present invention, a blower unit 352 constructed in analogy with the principle of an airturn is charged with hot waste air from a fuel cell unit 326, the hot air drying device according to the invention can also be used simultaneously for material web deflection.
Irrespective of the practical implementation of the invention in accordance with the embodiments described or other conceivable embodiments or exemplary embodiments of the invention, it will be expedient to supply the electrical energy provided by the fuel cell unit 26, 126, 226, 326 to the machine directly as direct current or as alternating current, in order thus to use the total energy given up before the fuel cell unit 26, 126, 226, 326 as completely as possible and thus to optimize the total energy balance of the system comprising fuel cell unit 26, 126, 226, 326 and the machine.
It is noted that the foregoing examples have been provided merely for the purpose of explanation and are in no way to be construed as limiting of the present invention. While the present invention has been described with reference to an exemplary embodiment, it is understood that the words which have been used herein are words of description and illustration rather than words of limitation. Changes may be made, within the purview of the appended claims, as presently stated and as amended, without departing from the scope and spirit of the present invention in its aspects. Although the present invention has been described herein with reference to particular means, materials and embodiments, the present invention is not intended to be limited to the particulars disclosed herein; rather, the present invention extends to all functionally equivalent structures, methods and uses, such as are within the scope of the appended claims.
Patent Application
20080023166
