GAS MEASURING DEVICE WITH HEATING MEANS

Abstract

A gas measuring device (100) for analyzing a gas mixture (310) and monitoring an environment (300) has a housing (110) for delimiting a measurement interior volume (120) and/or for separating the measurement interior volume (120) from the environment (300) containing the gas mixture (310). The housing has a gas inlet (111) and a gas outlet (112) for respective fluid-conducting connection between the measurement interior volume (120) and the environment (300), and an electrochemical gas sensor unit, which is arranged within the measurement interior volume (120), and which serves for determining a concentration of a gas fraction, in particular an oxygen fraction, contained in the gas mixture (310).

Claims

1. A gas measuring device (100) for analyzing a gas mixture (310) and for monitoring an environment (300), the gas measuring device (100) comprising: a housing (110) for delimiting a measurement interior volume (120) or for separating the measurement interior volume (120) from the environment (300) containing the gas mixture (310), the housing (110) having a gas inlet (111) and a gas outlet (112) for respective fluid-conducting connection between the measurement interior volume (120) and the environment (300), and a gas sensor unit (130), which is arranged within the measurement interior volume (120), for determining a concentration of a gas fraction, contained in the gas mixture (310), characterized in that the gas measuring device (100) has a heater (200) with at least one heating element (220) and with an open-loop or closed-loop control system (230), wherein, to increase or maintain an interior temperature (T.sub.I) of the measurement interior volume (120), a heating temperature (T.sub.H) of the at least one heating element (220) is settable by means of the open-loop or closed-loop control system (230).

2. The gas measuring device (100) according to claim 1, characterized in that the measurement interior volume (120) and the gas sensor unit (130) are in continuous, fluid-conducting exchange with the environment (300) containing the gas mixture (310) via the gas inlet (111) or the gas outlet (112), for continuous room monitoring.

3. The gas measuring device (100) according to claim 2, characterized in that the at least one heating element (220) comprises a heating resistor (221) on a radiator, wherein the heating temperature (T.sub.H) of the heating element (220) can be open-loop controlled by means of a heating voltage (222) applied to the heating resistor (221).

4. The gas measuring device (100) according to claim 1, characterized in that the open-loop or closed-loop control system (230) has at least one first temperature sensor (231) for measuring an instantaneous heating temperature (T.sub.H, Actual) of the at least one heating element (220) and is configured for the open-loop or closed-loop control of the instantaneous heating temperature (T.sub.H, Actual) on the basis of a presettable target heating temperature (T.sub.H, Target) of the at least one heating element (220).

5. The gas measuring device (100) according to claim 4, characterized in that the open-loop or closed-loop control system (230) has at least one second temperature sensor (231) for measuring a gas inlet temperature (T.sub.G) of the gas mixture (310) present at the gas inlet (111) or an ambient temperature (T.sub.U) of the gas mixture (310) present in the environment (300), and the presettable target heating temperature (T.sub.H, Target) can be determined, in each case depending on the measured gas inlet temperature (T.sub.G) and/or the measured ambient temperature (T.sub.U) on the basis of a correlation stored in the open-loop or closed-loop control system (230), between the interior temperature (T.sub.I) of the measurement interior volume (120) and the instantaneous heating temperature (T.sub.H, Actual) of the at least one heating element (220) or on the basis of an association, stored in the open-loop or closed-loop control system (230), of concrete values of the instantaneous heating temperature (T.sub.H, Actual) with corresponding values of the interior temperature (T.sub.I).

6. The gas measuring device (100) according to claim 5, characterized in that the open-loop or closed-loop system (230) of the heater (200) has a digital computation unit (235) which has interfaces with the at least one first temperature sensor (231), with the at least one second temperature sensor (232) and with the at least one heating element (220), and wherein the correlation between the interior temperature (T.sub.I) of the measurement interior volume (120) and the instantaneous heating temperature (T.sub.H, Actual) of the at least one heating element (220) or the association of concrete values of the instantaneous heating temperature (T.sub.H, Actual) with corresponding values of the interior temperature (T.sub.I) is or are stored in the computation unit (235), and the computation unit (235) is configured for determining the presettable target heating temperature (T.sub.H, Target) depending on the measured gas inlet temperature (T.sub.G) and/or the measured ambient temperature (T.sub.U).

7. The gas measuring device (100) according to claim 6, characterized in that the digital computation unit (235) is configured for outputting an error message or for switching off the heater (200) if a measured value of the instantaneous heating temperature (T.sub.H, Actual) is less than the temperature minimum reference value stored in the computation unit (235), or the measured value of the instantaneous heating temperature (T.sub.H, Actual) is greater than a stored temperature maximum reference value.

8. The gas measuring device (100) according to claim 1, characterized in that the gas measuring device (100) comprises a gas mixture return (260) with a gas mixture return line (261), wherein gas mixture (310) flowing out at the gas outlet (112) of the housing (110) can be at least partially supplied via the gas mixture return line (261) to the heating means (200).

9. The gas measuring device (100) according to claim 2, characterized in that the heater (200) has a fan (240) for generating a gas mixture flow (320).

10. The gas measuring device (100) according to claim 6, characterized in that the digital computation unit (235) is configured to increase or maintain the interior temperature (T.sub.I) of the measurement interior volume (120) of the gas measuring device (100) indirectly by heating a gas mixture flow (320) by the at least one heating element (220).

11. The gas measuring device (100) according to claim 3, characterized in that the heater (200) has a heater housing (210) for accommodating the at least one heating element (220) and for accommodating the open-loop and/or closed-loop control system (230), with a heater housing inlet (211) for fluid-conducting connection to the environment (300) and a heater housing outlet (212) for fluid-conducting connection with the gas inlet (111) of the housing (110) of the gas measuring device (100).

12. A heater (200) for a gas measuring device (100) for increasing or maintaining an interior temperature (T.sub.I) of a measurement interior volume (120) of the gas measuring device (100), having: a heater housing (210) with a heater housing inlet (211) for fluid-conducting connection with an environment (300) containing a gas mixture (310) and with a heater housing outlet (212) for fluid-conducting connection with the measurement interior volume (120) of the gas measuring device (100), at least one heating element (220) which is arranged within the heater housing (210), an open-loop or closed-loop control system (230) which is arranged within the heater housing (210) and which is configured for setting a heating temperature (T.sub.H) of the at least one heating element (220), characterized in that the open-loop or closed-loop control system (230) has at least one first temperature sensor (231) for measuring an instantaneous heating temperature (T.sub.H, Actual) of the at least one heating element (220) and is configured for the open-loop or closed-loop control of the instantaneous heating temperature (T.sub.H, Actual) on the basis of a presettable target heating temperature (T.sub.H, Target) of the at least one heating element (220), and has at least one second temperature sensor (232) for measuring a gas inlet temperature (T.sub.G) of the gas mixture (310) present at the heater housing inlet (211) or for measuring an ambient temperature (T.sub.U) of the gas mixture (310) present in the environment (300).

13. The heater heating m ns according to claim 12, characterized in that the presettable target heating temperature (T.sub.H, Target) can be determined on the basis of a correlation stored in the open-loop or closed-loop control system (230), between the interior temperature (T.sub.I) of the measurement interior volume (120) and the instantaneous heating temperature (T.sub.H, Actual) of the at least one heating element (220) or on the basis of an association, stored in the open-loop or closed-loop control system (230), of concrete values of the instantaneous heating temperature (T.sub.H, Actual) with corresponding values of the interior temperature (T.sub.I), in each case depending on the measured gas inlet temperature (T.sub.G) or the measured ambient temperature (T.sub.U).

14. A method for open-loop or closed-loop control (400) of a heater (200) with at least one heating element (220) for a gas measuring device (100) the method comprising the following steps: acquiring (410) a gas inlet temperature (T.sub.G) or an ambient temperature (T.sub.U), which is measured by means of a first temperature sensor (231), acquiring (420) an instantaneous heating temperature (T.sub.H, Actual) of the at least one heating element (220), which is measured by means of a second temperature sensor (232), computing (430) a target heating temperature (T.sub.H, Target) for the at least one heating element (220) depending on the measured gas inlet temperature (T.sub.G) or the measured ambient temperature (T.sub.U), open-loop or closed-loop controlling (440) of the instantaneous heating temperature (T.sub.H, Actual) based on the computed target heating temperature (T.sub.H, Target)

15. The method for open-loop or closed-loop control (400) according to claim 14, characterized by, open loop controlling the interior temperature (T.sub.I) of a measurement interior volume (120) of the gas measuring device (100) by means of the instantaneous heating temperature (T.sub.H, Actual) of the at least one heating element (220), wherein the computation of the target heating temperature (T.sub.H, Target) for the at least one heating element (220) occurs based on a correlation between the interior temperature (T.sub.I) and the instantaneous heating temperature (T.sub.H, Actual) or based on an association of concrete values of the instantaneous heating temperature (T.sub.H, Actual) with corresponding values of the interior temperature (T.sub.I).

16. The gas measuring device (100) according to claim 2, characterized in that, the environment (300) is a room containing the gas mixture and continuously being monitored by the gas measuring device (100), wherein the measurement interior volume (120) and the gas sensor unit (130) are in continuous, fluid-conducting exchange with the room.

17. The gas measuring device (100) according to claim 1, characterized in that, the gas sensor unit (130) is an electrochemical gas sensor unit for determining an oxygen gas fraction contained in the gas mixture.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0044] Other details, features, feature (sub)combinations, advantages and effects on the basis of the invention result from the following description of the preferred embodiment examples of the invention and the drawings. The drawings show, in

[0045] FIG. 1 a diagrammatic representation of the first exemplary embodiment of a gas measuring device according to the invention with integrated heating means,

[0046] FIG. 2 a diagrammatic representation of the second exemplary embodiment of a gas measuring device according to the invention with upstream heating means,

[0047] FIG. 3 a diagrammatic representation of a third exemplary embodiment of a gas measuring device according to the invention with upstream heating means and gas mixture return,

[0048] FIG. 4 a block diagram of an exemplary control loop of a closed-loop and/or open-loop control system of a heating means according to the invention, and

[0049] FIG. 5 a flow chart of an exemplary sequence of a method according to the invention for open-loop and/or closed-loop control of a heating means for a gas measuring device.

[0050] The figures are only of exemplary nature and used only for the understanding of the invention. The same elements are provided with the same reference numerals.

DETAILED DESCRIPTION OF THE INVENTION

[0051] In FIG. 1, a first exemplary embodiment of a gas measuring device 100 according to the invention with integrated heating means 200 is diagrammatically represented. The gas measuring device 100 comprises a housing 110 which separates a measurement interior volume 120 from an environment 300. Here, a gas inlet 111 and a gas outlet 112 are formed on mutually facing housing walls and in each case are provided for fluid-conducting connection with the environment 300. The environment 300 can be, for example, a protected zone of an oxygen reduction installation, within which a reduction of the oxygen content is carried out by introducing an inert gas. For monitoring this environment 300, by means of the gas measuring device 100, an analysis, in particular a continuous analysis, of a gas mixture 310, for example, of oxygen-reduced ambient air, present in the environment 300 can be carried out.

[0052] Advantageously, for this purpose, within the measurement interior volume 120 of the gas measuring device 100, a gas sensor unit 130 is placed, which, for the analysis of the gas mixture 310, determines the concentration of a gas fraction in particular an oxygen fraction, contained in the gas mixture 310. In an advantageous design, the gas sensor unit 130 is a commercial electrochemical oxygen sensor. The gas measuring device 100 can be placed within the environment 300 to be monitored, wherein a continuous exchange of the gas mixture 310 between the measurement interior volume 120 and the environment 300 occurs due to a gas mixture flow 320, generated, for example, by free convection, from the gas inlet 111 to the gas outlet 112. Alternatively and not shown in this figure, it is also conceivable to design the gas inlet 111 and the gas outlet 112 as an identical component and/or on the same housing wall, in that, for example, a pipe connection or a recess of the housing, protected by a grate, functions as gas inlet and outlet 111, 112. The gas mixture 310 is then let in or let out through the same opening or recess functioning as gas inlet and outlet 111, 112, wherein the gas mixture flow 320 then enters the housing 110 at the gas inlet and outlet 111, 112, passes through the gas sensor unit 130 and subsequently exits again from the gas inlet and outlet 111, 112.

[0053] In order to be able to determine the gas fraction contained in the gas mixture 310 being influenced by the ambient temperature T.sub.U, a heating means 200 is provided here as component of the gas measuring device 100. The heating means 200 in this embodiment comprises, for example, two heating elements 220 as well as an open-loop and/or closed-loop control system 230 with a digital computation unit 235, in particular a digital microcontroller, which is connected to a printed circuit board 236. Alternatively, it is also conceivable to integrate the heating elements 220 in a cover of the housing 110. The digital computation unit 235 is connected on the input side via interfaces to at least a first temperature sensor 231, in the present case to two first temperature sensors 231, for measuring an instantaneous heating temperature T.sub.H, Actual of the heating elements 220 and to at least one second temperature sensor 232 for measuring a gas inlet temperature T.sub.G present at the gas inlet 111 and/or an ambient temperature T.sub.U of the gas mixture 310 present in the environment 300. In the present embodiment example, the gas inlet temperature T.sub.G corresponds to the ambient temperature T.sub.U. On the output side, via corresponding interfaces of the computation unit 235, the heating elements 220 are actuated. Each heating element 220 has in particular a heating resistor 221 (see FIG. 4) and a radiator (not represented), which are thermally coupled to one another. By means of the heating elements 220, the interior temperature T.sub.I of the measurement interior volume 120 can be increased and/or maintained at a desired temperature level. By means of an optional fan 240, by forced convection, a gas mixture flow 320 can be generated, the flow rate of which and/or volume flow of which can be set or controlled based on the rotational speed of the fan 240.

[0054] A second exemplary embodiment of a gas measuring device 100 is diagrammatically represented in FIG. 2 and essentially has components which correspond to the components of the first exemplary embodiment, wherefore they are also not explained in greater detail again. However, unlike the first exemplary embodiment, the heating means 200 here is designed with its own separately implemented heater housing 210, the heater housing inlet 211 of which leads in a fluid-conducting manner into the environment 300, and the heater housing outlet 212 of which, here, for example, via a pipe connection 250, in particular via a plastic pipe provided with insulation 251, is connected to the gas inlet 111 of the housing 110 of the gas measuring device 100. Accommodated in the heater housing 210 are five heating elements 220 in total, which are actuated by the digital computation unit 235, not represented here, the open-loop and/or closed-loop control system 230 as well as a first temperature sensor 231 and a second temperature sensor 232. The second temperature sensor 232 for measuring the non-preheated gas inlet temperature T.sub.G or ambient temperature T.sub.U in this embodiment is arranged on the heater housing inlet 211. Also, within the heater housing 210, a fan 240 for generating a gas mixture flow 320 is provided. The gas mixture flow 320 is preheated here already in the heater housing 210, with regard to the flow direction of the gas mixture flow 320, upstream of the gas measuring device 100, by means of the heating elements 220. Here, an indirect increasing and/or an indirect maintaining of the interior temperature T.sub.I is implemented at the gas sensor unit 130. Optionally, the heating means 200 moreover comprises a third temperature sensor 233 which is arranged on the heater housing outlet 212, downstream of the heating elements 220, for measuring a preheating temperature T.sub.V of the already heated gas mixture flow 320. As desired, a fourth temperature sensor 234 can be provided in the measurement interior volume 120 or can be integrated in the gas sensor unit 130, in order to enable a monitoring of the interior temperature T.sub.I in the immediate vicinity of the gas sensor unit 130.

[0055] With respect to the second embodiment example, the third embodiment example of a gas measuring device 100 according to the invention according to the diagrammatic representation of FIG. 3, differs by a gas mixture return 260. The gas mixture return 260 comprises a gas mixture return line 261, the input-side end of which is connected in a fluid-conducting manner to the gas outlet 112 of the housing 110 of the gas measuring device 100 and the output-side end of which is connected to the heater housing inlet 211 of the heater housing 210. By means of the gas mixture return line 261, a partial flow of the gas mixture flow 320 flowing out at the gas outlet 112 can be diverted and returned via the heater housing inlet 211 to the heating means 200 and the heating elements 220. The returned partial flow of the gas mixture flow 320 converges at the heater housing inlet 211 with a partial flow of the gas mixture flow 320 coming from the environment 300 and is supplied as mixed flow to the heater housing inlet 211. In the heater housing inlet 211, the second temperature sensor 232 is arranged, wherein, in this embodiment example, the gas inlet temperature T.sub.G measured there has a higher value than the ambient temperature T.sub.U. Due to the gas mixture return 260, the total necessary heating power can be reduced. For further reduction, the housing 100, the heater housing 200 and/or the gas mixture return line 261 in each case can optionally be provided with insulation.

[0056] FIG. 4 shows a block diagram of an exemplary control loop of a closed-loop and/or open-loop control system 230 of a heating means 200 according to the invention. Herein, the digital computation unit 235 is connected by signal technology via input-side interfaces to a first temperature sensor 231 for measuring an instantaneous heating temperature T.sub.H, Actual and to a second temperature sensor 232 for measuring a gas inlet temperature T.sub.G and/or an ambient temperature T.sub.U. The temperature values measured by analog measurement in each case at the temperature sensors 231, 232 are converted by means of an appropriate analog-digital converter and are transmitted to the digital computation unit 235. The computation unit 235 performs a target value/actual value comparison with regard to the heating temperature T.sub.H, wherein the target heating temperature T.sub.H, Target is computed based on the measured gas inlet temperature T.sub.G and/or the measured ambient temperature T.sub.U. For the open-loop and/or closed-loop control of the instantaneous heating temperature T.sub.H, Actual, the computation unit 235 actuates a heating resistor 221, wherein the output signal digitally output by the computation unit 235 as pulse width modulation 238 is output to a switching power supply 239. Via the heating voltage 222 output by the switching power supply 239 and the heating resistor 221, the heating temperature T.sub.H of the heating element 220 is finally open-loop controlled.

[0057] For the indirect open-loop and/or closed-loop control of the interior temperature T.sub.I of the measurement interior volume 120 of the gas measuring device 100 by the represented control loop, in the computation unit 235, in particular on a storage unit 237, a correlation or another relationship between the interior temperature T.sub.I of the measurement interior volume 120 and the instantaneous heating temperature T.sub.H, Actual of the at least one heating element 220 and/or an association of concrete values of the instantaneous heating temperature T.sub.H, Actual with corresponding values of the interior temperature T.sub.I is stored. A desired interior temperature T.sub.I or a temperature range within which the interior temperature T.sub.I is to be maintained can be stored in the computation unit 235 or stored by a user.

[0058] Finally, shown in FIG. 5 is a flow chart of an exemplary sequence of a method according to the invention for open-loop and/or closed-loop control 400 of a heating means 200 with at least one heating element 220 for a gas measuring device 100 (see FIGS. 1-3). With the start of the open-loop and/or closed-loop control method 400, in a first step 410, a gas inlet temperature T.sub.G, measured by a second temperature 232 of the heating means 200 and/or a measured ambient temperature T.sub.U, is acquired. In a second step 420, an instantaneous heating temperature T.sub.H, Actual measured by a first temperature sensor 231 of the heating means 200 is acquired. The first step 410 and the second step 420 as desired can also be carried out successively or also in parallel or simultaneously.

[0059] In a third step 430, a target heating temperature T.sub.H, Target for the at least one heating element 220 is computed based on the gas inlet temperature T.sub.G measured in the first step 410 and/or the measured ambient temperature T.sub.U. For computing the target heating temperature T.sub.H, Target, in addition to the measured gas inlet temperature T.sub.G and/or the measured ambient temperature T.sub.U, a correlation or another relationship between the interior temperature T.sub.I of the measurement interior volume 120 of the gas measuring device 100 and the instantaneous heating temperature T.sub.H, Actual of the at least one heating element 220 and/or an association of concrete values of the instantaneous heating temperature T.sub.H, Actual with corresponding values of the interior temperature T.sub.I is/are preferably used. Preferably, before the start of the method 400, in a single step 431, the respective correlation or the other relationship and/or the association is/are in particular experimentally determined and stored in the open-loop and/or closed-loop control system 230, in order to be used in additional method runs in the third step 430 in each case for computing the target heating temperature T.sub.H, Target.

[0060] In a fourth step 440, the instantaneous heating temperature T.sub.H, Actual is open-loop and/or closed-loop controlled based on the computed target heating temperature T.sub.H, Target. Here, two successive target value/actual value comparisons 441, 442 are carried out between the instantaneous heating temperature T.sub.H, Actual and the target heating temperature T.sub.H, Target, wherein, in a first target value/actual value comparison 441, it is checked whether the instantaneous heating temperature T.sub.H, Actual is less than the target heating temperature T.sub.H, Target. In the case of a positive result of the test (if “Yes”), the at least one heating element 220 is correspondingly actuated, in that a pulse width modulation 238 transmitting the control signal is set “higher” 443, in particular the duty factor of the pulse width modulation 238, that is to say the ratio of the pulse duration to the period duration, is increased. In the case of a negative test result of the first target value/actual value comparison 441 (if “No”), then one continues with a second target value/actual value comparison 442, in which it is checked whether the instantaneous heating temperature T.sub.H, Actual is higher than the target heating temperature T.sub.H, Target. In the case of a positive result of the test (if “Yes”), the at least one heating element 220 is correspondingly actuated, in that a pulse width modulation 238 transmitting the control signal is set “lower” 444, in particular the duty factor of the pulse width modulation 238 is reduced. In the case of a negative test result of the second target value/actual value comparison 442 (if “No”), the instantaneous heating temperature T.sub.H, Actual corresponds to the target heating temperature T.sub.H, Target, and the method run is ended without actuation of the at least one heating element 220. Preferably, during the operation of the heating means 200 according to the invention, the described sequence is repeated at regular time intervals.

LIST OF REFERENCE NUMERALS

[0061] 100 Gas measuring device [0062] 110 Housing [0063] 111 Gas inlet [0064] 112 Gas outlet [0065] 120 Measurement interior volume [0066] 130 Gas sensor unit [0067] 200 Heating means [0068] 210 Heater housing [0069] 211 Heater housing inlet [0070] 212 Heater housing outlet [0071] 220 Heating element [0072] 221 Heating resistor [0073] 222 Heating voltage [0074] 230 Open-loop and/or closed-loop control system [0075] 231 First temperature sensor [0076] 232 Second temperature sensor [0077] 233 Third temperature sensor [0078] 234 Fourth temperature sensor [0079] 235 Digital computation unit [0080] 236 Printed circuit board [0081] 237 Storage unit [0082] 238 Pulse width modulation [0083] 239 Switching power supply [0084] 240 Fan [0085] 250 Pipe connection [0086] 251 Insulation [0087] 260 Gas mixture return [0088] 261 Gas mixture return line [0089] 300 Environment [0090] 310 Gas mixture [0091] 320 Gas mixture flow [0092] 400 Open-loop and/or closed-loop control method [0093] 410 Acquisition of a gas inlet temperature (T.sub.G) and/or of an ambient temperature (T.sub.U), first step [0094] 420 Acquisition of an instantaneous heating temperature (T.sub.H, Actual), second step [0095] 430 Computation of a target heating temperature (T.sub.H, Target), third step [0096] 431 Determination of a relationship between the instantaneous heating temperature (T.sub.H, Actual) and the interior temperature (T.sub.I) [0097] 440 Open-loop control and/or closed-loop control of the instantaneous heating temperature (T.sub.H, Actual), fourth step [0098] 441 First target value/actual value comparison [0099] 442 Second target/value/actual value comparison [0100] 443 Increasing the duty factor [0101] 444 Decreasing the duty factor [0102] T.sub.U Ambient temperature [0103] T.sub.G Gas inlet temperature [0104] T.sub.I Interior temperature [0105] T.sub.V Preheating temperature [0106] T.sub.H Heating temperature [0107] T.sub.H, Actual Instantaneous heating temperature [0108] T.sub.H, Target Target heating temperature