INFRARED RADIANT HEATER

Abstract

An infrared radiant heater, in particular a dark radiant heater or a bright radiant heater, includes a burner and a fan. The burner is connected to a combustion gas supply and the fan is designed to supply the burner with combustion air. The combustion gas supply is connected to a hydrogen source as a combustion gas source. A UV sensor is provided which is designed to detect at least one parameter of the flame generated by the burner.

Claims

1: An infrared radiant heater, in particular a dark radiant heater or a bright radiant heater, having a burner and a fan, wherein the burner is connected to a fuel gas supply, wherein the fan is set up for supplying combustion air to the burner, wherein the fuel gas supply is connected to a hydrogen source as the fuel gas source, wherein a UV sensor is provided that is set up for detecting at least one parameter of the flame produced by the burner.

2: The infrared radiant heater according to claim 1, wherein the infrared radiant heater is a dark radiant heater, which comprises a radiant tube in which the burner is arranged, wherein the UV sensor is directed at the base of the flame.

3: The infrared radiant heater according to claim 2, wherein the radiant tube is provided with a viewing window, wherein the UV sensor is directed at the base of the flame from outside of the radiant tube, through the viewing window.

4: The infrared radiant heater according to claim 2, wherein the radiant tube is connected to an exhaust gas discharge line, wherein a combustion air mixing chamber is arranged to precede the burner in the flame direction, which chamber is connected to a combustion air source and the exhaust gas discharge line.

5: The infrared radiant heater according to claim 4, wherein the fan is arranged to precede the burner in the flame direction, and the combustion air mixing chamber is arranged within the fan.

6: The infrared radiant heater according to claim 4, wherein an adjustment device is arranged on the discharge line, by means of which device the ratio of the exhaust gas volume stream of the exhaust gas discharge line to the combustion air volume stream of the combustion air source can be set.

7: The infrared radiant heater according to claim 1, wherein the infrared radiant heater is a bright radiant heater that has a radiant panel provided with flame passage channels, which serves as a radiating surface, wherein the burner is set up to bring about glowing of the radiant panel over its full area, and wherein the UV sensor is directed at the radiant panel so as to enclose an obtuse angle with it.

8: The infrared radiant heater according to claim 7, wherein a reflector that encloses the radiant panel, at least in certain regions, is provided, which is provided with a viewing window, wherein the optical sensor is directed at the radiant panel from outside of the reflector, through the viewing window.

9: The infrared radiant heater according to claim 8, wherein the reflector encloses the emission surface of the radiant panel and delimits an exhaust gas space, wherein a combustion air mixing space is arranged ahead of the burner, which space is connected to a combustion air source and the exhaust gas space.

10: The infrared radiant heater according to claim 9, wherein the exhaust gas space is connected to the combustion air mixing space by way of an ejector, wherein the driving medium of the ejector is combustion air introduced by means of the fan, and the medium drawn into the combustion air mixing space is exhaust gas situated in the exhaust gas space.

11: The infrared radiant heater according to claim 10, wherein an adjustment device is provided, by way of which the ratio of the combustion air volume stream to the exhaust gas volume stream of the ejector that is drawn in can be set.

12: The infrared radiant heater according to claim 1, wherein the UV sensor is connected to a setting device connected to the fuel gas supply, for interrupting and/or setting the hydrogen supply.

13: The infrared radiant heater according to claim 1, wherein the UV sensor is set up for NOX measurement, in particular by means of UV resonance absorption spectroscopy.

14: The infrared radiant heater according to claim 1, wherein the setting device and/or the adjustment device is connected to a control and regulation module that is programmed to regulate the flame properties by means of a comparison of the actual parameter transmitted by the UV sensor with a stored reference parameter, by means of changing the hydrogen volume stream and/or the combustion air volume stream and/or the ratio of exhaust gas stream and combustion air stream.

15: The infrared radiant heater according to claim 14, wherein the actual parameter is a NOX value detected by the UV sensor, wherein the control and regulation module is programmed to regulate the flame temperature on the basis of the difference between the actual value and a stored reference value, by means of changing the hydrogen stream and/or the combustion air stream and/or the ratio of exhaust gas stream and combustion air stream.

Description

[0021] Other further developments and embodiments of the invention are indicated in the other dependent claims. Exemplary embodiments of the invention are shown in the drawings and will be described in detail below. The figures show:

[0022] FIG. 1 the schematic representation of an infrared radiant heater in the form of a dark radiant heater, and

[0023] FIG. 2 the schematic representation of an infrared radiant heater in the form of a bright radiant heater.

[0024] The dark radiant heater according to FIG. 1, chosen as an exemplary embodiment, comprises a burner 1 that is connected to a fan 3 and followed by a radiant tube 4. The radiant tube 4 is merely indicated in FIG. 1; the radiant tube 4 can certainly extend over a length of several meters and can be formed from multiple radiant tube elements. In the exemplary embodiment, the radiant tube 4 is configured as a highly heat-resistant stainless steel tube. Alternatively, special steels with a thermally applied aluminum oxide layer can also be used. In the exemplary embodiment, the radiant tube 4 is enclosed by a reflectornot shownwhich is formed from surface-structured sheet aluminum in the exemplary embodiment, and which has bulkhead plates on both sides, for the reduction of convective losses.

[0025] The burner 1 comprises a gas jet 21 that is connected to a hydrogen supply 2. An ignition electrode 11 is arranged in the burner 1, at a distance from the gas jet 21. On its side of the burner 1 facing away from the ignition electrode 11, the fan 3 is set in such a way that is flushes the gas jet 21 with combustion air. For this purpose, the fan 3 is connected, on the suction side, to a combustion air supply 31.

[0026] The hydrogen stream, which exits from the gas jet 21 under pressure, mixes with the combustion air stream, which flushes the gas jet 21, and is ignited when the required mixture ratio is reached, by means of the ignition electrode 11 arranged at a distance from the gas jet 21, and thereby a flame 15 is formed at a distance from the gas jet 21, which flame extends into the radiant tube 4, over its length. In the region 22 of the hydrogen stream that is not capable of ignition, which does not have a sufficient mixture ratio with combustion air, no flame formation takes place.

[0027] A sensor holder 13 is introduced into the housing 12 of the burner 1, which holder has a window 14. A UV sensor 5 is introduced into the sensor holder 13, which sensor is connected to a setting device 32 for interrupting the hydrogen supply 2, by way of an electrical line 51. In the exemplary embodiment, the UV sensor 5 is directed centered on the flame base 151 of the flame 15. If no flame 15 is detected by the UV sensor 5, the hydrogen supply is interrupted by the setting device 32.

[0028] The control and regulation module 33, in the present case a setting valve, which is connected to the setting device 32, is additionally connected to the ignition electrode 11 here, and set up in such a manner that in the event that no flame is detected, first the ignition electrode 11 is activated, and only after there continues to be no flame, an interruption of the hydrogen supply takes place.

[0029] In an optional expansion, the fan 3 can be connected, on its suction side, to an ejector, the drive connector of which is connected to a combustion air supply 31, and the suction connector of which is connected to an exhaust gas supply, which is supplied by an exhaust gas line, which is connected to the radiant tube 4 on the exhaust gas side. The combustion air drawn in by the fan 3 serves as a driving medium here, by means of which intake of the exhaust gas is brought about. On the pressure side, in this way an exhaust gas/combustion air mixture is supplied to the gas jet 21, by means of the fan 3, which mixture flushes the gas jet 21. The exhaust gas/combustion air mixture has a reduced oxygen content, and thereby a flame having a reduced temperature is brought about. On the basis of the great reactivity of hydrogen, even a low oxygen content in the exhaust gas/combustion air mixture is sufficient for ignition, and thereby a flame 15 that extends through the radiant tube 4 is produced. By means of an adjustment device arranged in the exhaust gas line or in the ejector, for example an adjustment shutter or a setting valve, it is possible to set the mixture ratio of exhaust gas volume stream and combustion air volume stream.

[0030] In the exemplary embodiment, the UV sensor 5 is set up for NOX measurement by means of UV resonance absorption spectroscopy, and is connected to the control and regulation module 33. In this regard, the control and regulation module 33 is programmed in such a manner that the actual NOX value delivered by the UV sensor 5 is compared to a stored reference value, and based on the difference of the two values, regulating the flame properties by means of changing the hydrogen volume stream and/or the combustion air volume stream. For this purpose, the control and regulation module 33 is connected to the setting device 32, by way of which the hydrogen volume stream and the combustion air volume stream can be set. If the fan 3 is provided with the ejector described above, then the programming can additionally undertake regulation of the flame properties by way of an adjustment of the ratio of exhaust gas stream and combustion air stream. For this purpose, the adjustment device is connected to the control and regulation module 33. The setting device 32 and the control and regulation module 33 are merely indicated schematically in the figures, and connected to the points of action with broken lines.

[0031] If the fan 3 according to the exemplary embodiment according to FIG. 2 is connected to an ejector on the suction side, by way of which ejector mixing an exhaust gas stream into the combustion air stream takes place, then the ejector or the exhaust gas supply line that supplies it on the suction side can be provided with an adjustment device, by way of which the mixture ratio of exhaust gas stream and combustion air stream can be set. If the UV sensor is set up for UV resonance absorption spectroscopy, regulation of the flame temperature on the basis of a NOX content detected by the UV sensor is possible. For this purpose, it is practical if the sensor is connected to a regulation module, the reference value of which is a predetermined reference NOX value, wherein the actual NOX value is supplied by the UV sensor. On the basis of the difference between the reference value and the actual value, adjustment of the mixture ratio of exhaust gas stream and combustion air stream can take place by way of control of the adjustment device, and thereby a change in the temperature of the flame 6 is brought about, which in turn brings about a change in the actual NOX value.

[0032] In the exemplary embodiment according to FIG. 2, the infrared radiant heater is configured as a bright radiant heater and comprises a burner 6 that is connected to a hydrogen supply 7 and a fan 8. A reflector 9 is arranged to enclose the burner 6.

[0033] The burner 6 comprises a fuel mixing chamber 61, which is delimited by a ceramic radiant panel 62. The ceramic radiant panel 62 is provided, in a known manner, with a hole pattern that extends over the entire surface, formed by cylindrical flame passage channels, which are configured to widen conically on the side of the radiant panel 62 that is directed outward. Lying opposite the radiant panel 62, a hydrogen supply 7 is arranged orthogonal to the panel, which supply opens into the fuel mixing chamber 61. At a right angle to the hydrogen supply 7, a pressure line 81 opens into the fuel mixing chamber 61, which line is connected to the fan 8.

[0034] On the suction side, the fan 8 is connected to a combustion air supply 82, wherein an ejector 83 is inserted into the pressure line 81, within the reflector 4, by means of which ejector a suction gap 84 that radially encompasses the pressure line 81 is formed. The section of the pressure line 81 that follows the ejector 83 forms a combustion air mixing space 86. The combustion air stream drawn in by the fan 8, by means of the combustion air supply 82, serves as a driving medium here, by means of which suctioning in of part of the exhaust gas cushion 851 situated within the reflector 9, through the suction gap 84, is brought about. The remaining exhaust gas stream 85 flows out of the reflector 9 into the ambient air. The width of the suction gap 84 can be set by way of an adjustment device present in the ejector 83, and thereby, in turn, the proportion of the exhaust gas stream 85 in the exhaust gas/combustion air stream mixture and thereby its oxygen content can be set.

[0035] The exhaust gas/combustion air mixture that exits from the combustion air mixing space 86 of the pressure line 81 is mixed with the hydrogen stream introduced by means of the hydrogen supply 7, and, once again, after exiting through the radiant panel 82, ignited by means of a the ignition electrode 63 arranged on the burner 6, on the outside, in front of the radiant panel 62.

[0036] A sensor holder 91 is affixed in the reflector 9, which holder has a window 92. A UV sensor 5 is introduced into the sensor holder, which sensor is connected to a setting device 32 for interrupting the hydrogen supply, by way of an electrical line 51. In the exemplary embodiment, the UV sensor 5 is oriented at an angle of 45 relative to the radiant panel 62. If no flame is detected by the UV sensor 5, then the hydrogen supply is interrupted by the setting device 32, a setting valve in the present case. The setting device 32 or the control and regulation module 33 connected to it can be additionally connected, here too, to the ignition electrode 63, and set up in such a manner that in the event that no flame is detected, first the ignition electrode 63 is activated, and only after there continues to be no flame, interruption of the hydrogen supply takes place.

[0037] In this exemplary embodiment, as well, a UV sensor 5 can be used that is set up for NOX measurement by means of UV resonance absorption spectroscopy and connected to a control and regulation module that is connected to the setting device 32 for interrupting the hydrogen stream and/or the combustion air stream, wherein the control and regulation module 33 is programmed in accordance with the above explanations relating to the dark radiant heater. In addition, the programming can undertake regulation of the flame properties by way of adjusting the ratio of exhaust gas stream and combustion air stream, by way of the adjustment device of the ejector 83. For this purpose, the adjustment device is connected to the control and regulation module 33.