Gas Regulating Unit, Gas Regulating Valve And System With Such A Gas Regulating Valve For Fail-Safe Pressure Regulation In A Gas Heater

Abstract

A gas regulating unit (10) for fail-safe regulation of a gas, specifically in a gas heater (1) or a gas burner, has a communication interface (15), a first sensor assembly (11), and a second sensor assembly (12). The first sensor assembly (11) is configured to acquire measured values from which a signed first differential pressure (p11) between a process pressure (p1) of the gas and a reference pressure (p0) is determinable. The second sensor assembly (12) is configured to acquire measured values from which a signed second differential pressure (p12) between the reference pressure (p0) and the process pressure (p1) is determinable. Thus, the signed first differential pressure (p11) and the signed second differential pressure (p12) are signed mutually inverse differential pressures (p11, p12). The communication interface (15) is configured to send the mutually inverse differential pressures (p11, p12) and/or the measured values to an external receiver.

Claims

1. A gas regulating unit for fail-safe regulation of a gas, specifically in a gas heater or a gas burner, comprising: a communication interface, a first sensor assembly, and a second sensor assembly; the first sensor assembly is configured to acquire measured values from which a signed first differential pressure (p11) between a process pressure (p1) of the gas and a reference pressure (p0) is determinable; the second sensor assembly is configured to acquire measured values from which a signed second differential pressure (p12) between the reference pressure (p0) and the process pressure (p1) is determinable, so that the signed first differential pressure (p11) and the signed second differential pressure (p12) are signed mutually inverse differential pressures (p11, p12); and the communication interface is configured to send the mutually inverse differential pressures (p11, p12) and/or the measured values to an external receiver.

2. The gas regulating unit according to claim 1, wherein the first sensor assembly is a first differential pressure sensor or is a first mass flow sensor or has at least two sensors, each configured as a pressure sensor or as a mass flow sensor, and/or wherein the second sensor assembly is a second differential pressure sensor or is a second mass flow sensor or has at least two sensors, each configured as a pressure sensor or as a mass flow sensor.

3. The gas regulating unit according to claim 1, wherein the first sensor assembly is a first differential pressure sensor and the second sensor assembly is a second differential pressure sensor; the differential pressure sensors each have a first pressure input and a second pressure input and are configured to ascertain a differential pressure (p11, p12) by subtracting a pressure applied to the second pressure input from a pressure applied to the first pressure input; the process pressure (p1) is applied to the first pressure input of the first differential pressure sensor, and the reference pressure (p0) is applied to the second pressure input of the first differential pressure sensor; the reference pressure (p0) is applied to the first pressure input of the second differential pressure sensor, and the process pressure (p1) is applied to the second pressure input of the second differential pressure sensor, so that the differential pressures (p11, p12) ascertained by the two differential pressure sensors (11, 12) are mutually inverse.

4. The gas regulating unit according to claim 1 further comprising: control electronics signalling connected to the first sensor assembly and the second sensor assembly and configured to acquire the mutually inverse differential pressures (p11, p12) or determine them from the measured values.

5. The gas regulating unit according to claim 4 further comprising: an actuator interface for triggering an actuator, specifically a stepper motor, signalling connected to the control electronics or formed integrally with the control electronics.

6. The gas regulating unit according to claim 4, wherein the communication interface is signalling connected to the control electronics or is formed integrally with the control electronics, the communication interface is specifically configured to receive control signals.

7. A gas regulating valve for fail-safe regulation of a gas in a gas heater or a gas burner comprising: a gas regulating unit according to claim 1 and a final control element for adjusting passage of a gas flowing from an inflow side to an outflow side of the gas regulating valve; and the process pressure (p1) is the pressure of the gas on the outflow side of the gas regulating valve.

8. The gas regulating valve according to claim 7, wherein the reference pressure (p0) is an ambient pressure at the gas regulating unit and/or the gas regulating valve.

9. The gas regulating valve according to claim 7 further comprising: an actuator signalling connected to the actuator interface of the gas regulating unit and configured to adjust the final control element for adjusting the passage.

10. The gas regulating valve according to claim 9, wherein the control electronics are configured to adjust the final control element for adjusting the passage by triggering the actuator until at least one of the differential pressures (p11, p12) and/or measured values corresponds to a predetermined value and/or is 0 Pa.

11. A system for fail-safe regulation of a gas in a gas heater or a gas burner comprising: a control unit for regulating combustion and a gas regulating valve according to claim 7; the control unit is signalling connected to the communication interface of the gas regulating unit as an external receiver and is configured to receive and process the mutually inverse differential pressures (p11, p12) and/or to send control signals to the communication interface.

12. The system according to claim 11, wherein the control unit is configured to plausibility check the mutually inverse differential pressures (p11, p12) by comparing the mutually inverse differential pressures (p11, p12) with target values or threshold values stored in the control unit, and/or plausibility check the mutually inverse differential pressures (p11, p12) by comparing the absolute values of the mutually inverse differential pressures (p11, p12) with one another, and/or plausibility check the application of the process pressure (p1) and the reference pressure (p0) to the sensor assemblies (11, 12).

13. A method for plausibility checking differential pressures (p11, p12) acquired with a system for fail-safe pressure regulation according to claim 11 comprising: triggering the final control element of the gas regulating valve or a safety valve, provided upstream of the gas regulating valve, to change the process pressure (p1), so that the change in the process pressure (p1) changes the first differential pressure (p11) and the second differential pressure (p12) inversely to one another; comparing, after their change, the mutually inverse differential pressures (p11, p12) with a respective target value or threshold value, and by means of the comparison; checking whether the first differential pressure (p11) associated with the first sensor assembly is the differential pressure acquired from the first sensor assembly, and/or whether the second differential pressure (p12) associated with the second sensor assembly is the differential pressure acquired from the second sensor assembly, and/or whether the process pressure (p1) is applied to the first sensor assembly as intended, and/or whether the reference pressure (p0) is applied to the first sensor assembly as intended, and/or whether the reference pressure (p0) is applied to the second sensor assembly as intended, and/or whether the process pressure (p1) is applied to the second sensor assembly as intended.

14. The method according to claim 13, wherein a fault is detected and output if the mutually inverse differential pressures (p11, p12) do not correspond to the respective target values or do not reach the respective threshold values.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0061] Other advantageous developments of the disclosure are characterised in the dependent claims or are presented in further detail below along with the description of the preferred embodiment of the disclosure with reference to the figures. In the drawings:

[0062] FIG. 1 depicts a schematic block diagram of a gas heater;

[0063] FIG. 2 depicts a schematic block diagram of a gas regulating valve;

[0064] FIG. 3 depicts a first pressure diagram for plausibility checking in a first operating mode;

[0065] FIG. 4 depicts a second pressure diagram for plausibility checking in a second operating mode.

DETAILED DESCRIPTION

[0066] The figures are schematic by way of example. Like reference numbers in the figures indicate like functional and/or structural features.

[0067] In FIG. 1, a section or part of a gas heater 1, specifically a gas boiler, is shown schematically and by way of example, wherein the gas regulating valve 2 illustrated in FIG. 2 as well as the gas regulating unit 10 contained therein may each be the gas regulating valve 2 and the gas regulating unit 10 according to FIG. 1, however, in principle may also be contemplated independently of the gas heater 1 or built into other installations or devices. Although the components and functions of FIGS. 1 and 2 are described collectively in the present document, what is disclosed with respect to FIG. 2, specifically, may also be contemplated independently of the exemplary embodiment according to FIG. 1.

[0068] FIG. 1 schematically depicts a part or a section of a gas heater 1 and more precisely the schematic construction of a gas-air system of a gas heater 1, wherein a venturi mixer is shown as a mixing apparatus 7, in which air is drawn in from the environment by a blower 8 through an air inlet L at an air pressure p0. In the mixing apparatus 7, the air flowing in and a fuel (gas) flowing in through the fuel supply G are mixed to form a gas-air mixture.

[0069] The gas flowing in from the fuel supply G flows to the mixing apparatus 7 through a safety valve 5 with a final control element 40 adjustable by an actuator 50, a gas regulating valve 2 with a valve or final control element 30 configured, for example, as a proportional valve, as well as a main flow restrictor 6.

[0070] The safety valve 5 or its final control element 40 preferably has a through position and a blocking position between which the actuator 50 may be switched, wherein the passage of the fuel or gas is enabled in the through position and blocked in the blocking position. The safety valve 5 may additionally or alternatively also be manually actuatable or actuatable by hand.

[0071] The gas regulating valve 2 is configured to regulate the volumetric or mass flow of the gas, so that the gas or the flow of the gas through the gas regulating valve 2 to the mixing apparatus 7 is adjustable or regulatable.

[0072] Thus, adjusting or regulating the flow of the gas using the gas regulating valve 2 as well as by means of a main flow restrictor 6 provided, as appropriate, between the gas regulating valve 4 and the mixing apparatus 7, causes the mixing ratio of the gas-air mixture in the mixing apparatus 7 to be regulatable or adjustable.

[0073] The gas-air mixture is further conveyed by the blower 8 into a burner 9 or its combustion chamber, where the combustion of the gas-air mixture takes place.

[0074] To regulate the gas flow or the passage through the gas regulating valve 2, it has a final control element 30, for example configured as a proportional valve, as shown, whose position is adjustable by an actuator 20, specifically configured as a stepper motor, as well as a gas regulating unit 10.

[0075] The gas regulating unit 10 itself is not configured to be fail-safe, but alongside control electronics 13, an actuator interface 14 signalling connected to the control electronics 13, as well as a communication interface 15 signalling connected to the control electronics 13, it comprises two sensor assemblies 11, 12, each configured as a differential pressure sensor 11, 12.

[0076] It is essential for the shown embodiment, on the one hand, that the respective differential pressure p11, p12 is acquired by the respective differential pressure sensor 11, 12 not only as an absolute value (i.e., unsigned), but in each case as signed pressure values or signed differential pressures. In this context, the differential pressures result from, for example, subtracting a pressure applied to each respective second pressure input 11B, 12B from a pressure applied to each respective first pressure input 11A, 12A, so that, depending on the respective applied pressures, signed pressure values may result for the differential pressures.

[0077] On the other hand, it is essential for the shown embodiment that a same pressure, denotable as a process pressure p1, is applied or applicable to the first pressure input 11A of the first differential pressure sensor 11 and to the second pressure input 12B of the second differential pressure sensor 12, as well as a same pressure, denotable as a reference pressure p0, is applied or applicable to the second pressure input 11B of the first differential pressure sensor 11 and to the first pressure input 12A of the second differential pressure sensor 12, so that the differential pressures p11, p12 ascertained by the two differential pressure sensors 11, 12 are mutually inverse.

[0078] As shown in FIGS. 1 and 2, it is provided in the present document that one separate pressure channel each leads to the first pressure input 11A of the first differential pressure sensor 11 and to the second pressure input 12B of the second differential pressure sensor 12 to the measurement point of the process pressure, whereas the pressure channels from the second pressure input 11B of the first differential pressure sensor 11 and from the first pressure input 12A of the second differential pressure sensor 12 to the measurement point of the reference pressure are formed integrally with one another in sections.

[0079] In this context, the process pressure p1 is a gas pressure in the gas regulating valve 2 on the discharge or outflow side of the final control element 30, and the reference pressure p0 is an air pressure at the gas regulating valve 2 or at the air inlet L, which may, however, deviate from the ambient pressure poo.

[0080] While the gas regulating valve 2 itself is not configured to be fail-safe, the gas heater 1 must be operable in a fail-safe manner. For this purpose, the differential pressures p0, p1 are transferred from the gas regulating valve 2 via the communication interface 15 to a control unit 3, which may check on the basis of the absolute values whether a measuring error is present. In the prior art, however, such control units 3 cannot verify whether the differential pressures associated with the first differential pressure sensor 11 and the second differential pressure sensor 12 have actually been measured by the respective differential pressure sensor 11, 12.

[0081] To form a system 4 consisting of the control unit 3 and the gas regulating valve 2 which is fail-safe overall, the signed pressure values are transferred to the control unit 3 from the gas regulating valve 2 or via the communication interface 15 of the gas regulating unit 10.

[0082] Since in normal combustion operation of the gas heater 1, the goal is usually zero-pressure regulation, the process pressure p1 substantially corresponds to the reference pressure p0, so that the differential pressures p11, p12 fluctuate in the range around 0 (e.g., 0 Pa or 0 bar). Due to measurement inaccuracies, in this regard, it is usually not possible to reliably deduce a fault from the respective sign.

[0083] Hence, the control unit 3 is configured to plausibility check the differential pressures p11, p12 in certain operating modes or within the framework of certain methods, i.e., to check for faults, with a pressure diagram according to FIGS. 3 and 4 resulting in each case.

[0084] Since the plausibility check is usually not conductable in a reliable manner during normal combustion operation or burner operation, it is provided according to a first method variant, the pressure curve of which being shown in FIG. 3, that the plausibility check is conducted during or in parallel with ventilation and specifically in a pre-flushing phase, in which the burner 9 or its combustion chamber is flushed or ventilated with air. For this purpose, the safety valve 5 and/or the gas regulating valve 2 is triggered to completely block a gas stream or a gas flow to the mixing apparatus 7 during the ventilation and, herein, in the pre-flushing phase, wherein the blower 8 continues to draw in air, so that a suction pressure of the blower 8 consequently ensues at the process pressure measurement point. As an alternative to the pre-flushing phase, the described method may also be conducted in a post-flushing phase.

[0085] The pressure curve ensuing therefrom is illustrated in FIG. 3, wherein at time T1, the blower 8 is switched on with the safety valve 5 and/or gas regulating valve 2 closed, and at time T2, the closed valves (safety valve 5 and/or gas regulating valve 2) are opened to enable passage.

[0086] Assuming the exemplary curve, during the ventilation and, herein by way of example, in the pre-flushing phase (specifically between times T1 and T2), a signed maximum pressure value of 4 ensues for the first differential pressure p11, and a signed maximum pressure value of +4 ensues for the second differential pressure, these being shown as and assumed to be unitless in the present document.

[0087] Since it is known that p11 results from p1-p0, and p12 results from p0-p1, and due to the ventilation, also that a lower value ensues for p1 than for p1, it may be deduced directly by means of the respective sign whether the values transmitted to the control unit 3 are correctly associated with the differential pressure sensors. In this context, the ratios and necessary assumptions need not necessarily be maintained in the control unit 3. It is sufficient, for example, for a fault to be assumed if p11 during the ventilation or p11 at a certain time during the ventilation or an average value of p11 during the ventilation is >0, and/or if p12 during the ventilation or p12 at a certain time during the ventilation or an average value of p12 during the ventilation is <0.

[0088] Consequently, if the differential pressure p12 is positive and the differential pressure p11 is negative, the differential pressure p12 is correctly associated with the second differential pressure sensor 12, and the differential pressure p11 is correctly associated with the first differential pressure sensor 11, so that the differential pressures or the pressure values have been plausibility checked. If this is not the case, a fault is present, so that correspondingly, a fault message may be output and/or the gas heater 1 may be switched off and/or switched to a safe mode.

[0089] Since this variant only enables a plausibility check during ventilation and, for example, in pre-flushing operation (or in post-flushing operation), it may alternatively or additionally also be provided that, during combustion operation or burner operation, the control unit 3 switches to a plausibility check mode for a short time in which there is no zero-pressure regulation for a short time, but a target pressure difference X of 2, for example, is set, as shown in FIG. 4, wherein other predetermined target pressure values X are also possible which should, however, exceed a measurement tolerance of the differential pressure sensors 11, 12. In the plausibility check mode, deliberate stimulation of the differential pressure sensors 11, 12 occurs for a short time, wherein the plausibility check may occur based on their behaviour or the signed pressure values ascertained in this context.

[0090] Correspondingly, a target differential pressure of 2 may be specified to the control electronics 13 by the control unit 3 via the communication interface 15, so that the control electronics 13 set the final control element 20 via the actuator electronics or actuator interface 14 in such a way that the new target differential pressure X ensues at at least one of the differential pressure sensors 11, 12 or at both of the differential pressure sensors 11, 12 at least for a short time. Subsequently, and specifically insofar as no fault is detected, it is possible to switch directly back to normal combustion operation.

[0091] If the new target differential pressure X of 2, for example, has been reached, it may again be deduced directly whether the signed pressure values are associated with the correct differential pressure sensor 11, 12. In this context, it should be considered that during the ventilation, i.e., herein in the pre-flushing phase, only a suction pressure may ensue for the process pressure, so that consequently, during the ventilation, or herein in the pre-flushing phase, p1<p0 always applies. In the mentioned plausibility check operation or mode, however, it may be freely determined and specified, and adjusted by triggering the final control element 30 of the gas regulating valve 2, whether the passage of the gas is to be increased or reduced, so that, depending on the desired trigger, p1<p0 (negative pressure) or p1>p0 (positive pressure) may apply. In this context, the pressure curve according to FIG. 4 corresponds to the variant of p1>p0, so that

[00002]$p11=p1-p0>0,\mathrm{and}$$p12=p0-p1<0.$

[0092] If, in turn, the differential pressures p11 and p12 do not have the sign nor the target or threshold value previously known and maintained for each case (p1<p0 or p1>p0), a fault is again present, so that again, correspondingly, a fault message may be output and/or the gas heater 1 may be switched off and/or switched to a safe mode.

[0093] The embodiments of the disclosure are not limited to the preferred exemplary embodiments indicated above. Rather, a number of variants are possible, which make use of the described solution in fundamentally different embodiments.