EP1698828A2 - Combustion system, in particular system for regulating a combustion system according to its ventilation or exhaust actual conditions - Google Patents

Abstract

The system has a combustion chamber (1) having an attached exit gas line arrangement (3, 5) for exhaust gases. A controllable mechanism (7, 17, 23, 29, 33, 64) influences operating conditions of the combustion chamber. A flow measuring instrument (35) is provided to record the exhaust gas flow in the exit gas line arrangement. The control equipment (53) in addition steers the mechanism to influence the operating conditions of the combustion chamber in accordance with the condition of the measurement effects of the flow measuring instrument. An independent claim is included for a method.

Description

The invention relates to a furnace with a fireplace, connected to the fireplace exhaust line arrangement for the derivation of the combustion process in the fireplace resulting exhaust gases, a controllable means for influencing the operating conditions of the fireplace and a control device for controlling the device for influencing the operating conditions of the fireplace. The invention is particularly concerned with the problem of the ventilation or exhaust gas control for furnaces, such. Stoves, gas heaters etc.

The combustion operation of a fireplace of the type considered here depends in each case on given fuel in particular from the supply of combustion air and from the chimney draft and thus the exhaust gas flow in the exhaust gas line arrangement. Thus, e.g. when installed in living rooms stoves or gas boiler the combustion air supply depend on whether supply flaps are open or closed, living room windows are open or closed, if a living room ventilation device, such as a component of an air conditioner is currently in operation, whether a ventilation device or possibly a cooker hood currently is in operation, etc. The exhaust flow depends inter alia from the Kamingeometrie, the temperature difference between the firing side connection and the chimney outlet of the exhaust pipe arrangement and any weather conditions, such as air pressure, wind, etc. from. For influencing the exhaust gas flow, draft limiters, exhaust gas flaps, exhaust gas extraction devices, etc. are known.

The invention has for its object to provide an improved furnace system of the type mentioned and in particular a control and operating concept for such a furnace, which allows a reliable and largely optimized combustion operation of the fireplace.

To achieve this object, the invention proposes that a flow measuring arrangement is provided and adapted to detect the exhaust gas flow in the exhaust pipe assembly by measurement, wherein the control device is prepared to control the device for influencing the operating conditions of the fireplace in accordance with measurement effects of the flow measuring arrangement.

As means for influencing the operating conditions of the fireplace, e.g. in question: motor controllable inlet flaps, supply air blower, extractor hoods, living room ventilation devices, etc. The above-mentioned components or facilities relate to the aspect of influencing the combustion air supply. Other suitable devices for influencing the operating conditions of the fireplace are: engine-controllable draft regulators, motor-controllable exhaust flaps, smoke extraction devices, etc. The latter components or devices relate to the aspect of influencing the exhaust gas flow.

According to the invention, at least one operating condition on the supply air side or on the exhaust side of the fireplace is influenced as a function of the measured exhaust gas flow and thus as a function of the chimney draft. Furthermore, the operating temperature of the fireplace or / and a temperature derived therefrom, for example the room temperature in the installation room of the fireplace, are preferably also measured and included in the control of the components influencing the operating conditions. In addition, it may be provided that the state of further, the combustion air supply or optionally the exhaust gas flow mitbestimmender elements is queried by means of relevant sensors from the control device and included in the control process or control process. As an example of this, for example, be monitored by the controller window switch, which opens the states living room window and closed housing window closed. In a stove, a corresponding furnace door switch may be provided, by means of which the control device the Can monitor closed state of the oven door.

Preferably, means for detecting the respective positions of flap components of the furnace, such as continuously or continuously controllable or discontinuously controllable Zuluftklappen, exhaust valves, draft regulators, etc. are provided.

In a further embodiment of the invention with a smoke evacuator is further provided that also the current operating state of the smoke evacuator is detected and queried by the control device.

The controller is programmed to incorporate the states of the monitored parameters into the control of the firing site's firing condition.

An embodiment of the invention relates to a combustion chamber with a room-air-independent fireplace, which has a combustion air supply arrangement, wherein a flow measuring arrangement is provided for detecting the combustion air flow in the Verbrennungsluftzuführungsanordung. In this case, the control device is set up to influence the combustion operating conditions of the fireplace also under consideration of the measured combustion air flow in the sense of optimizing the combustion mode.

For the flow measurement in the exhaust pipe arrangement and - if provided - for the flow measurement in the combustion air supply, a respective temperature measuring arrangement is preferably used to detect a temperature difference in the flowing medium between two consecutive points in the flow path, wherein at least one provided between the two locations controllable temperature influencing element serves to locally cause a change in temperature of the flowing medium (exhaust gas or possibly supply air), which then as a flow-dependent measurement effect in the temperature difference measurement can be detected.

The prior art of such a flow measuring arrangement and measurement mode is referred to the DE 196 23 174 C1.

As already explained in DE 196 23 174 C1, the temperature measuring sensor is preferably a thermocouple in question, which already allows a temperature difference detection at two measuring points.

The flow measuring arrangement makes it possible to determine whether, in which direction and at what speed the medium flows. If the medium flows, for example, in the direction from the first location to the second location of the temperature difference monitoring, the "thermal disturbance" triggered by the temperature influencing element is carried by the flowing medium to the downstream, ie second measuring point, so that there a temperature change with respect to the upstream, ie Here the first measuring point is recorded. If the medium flows in the opposite direction, this is to be determined in a corresponding manner on the basis of the temperature difference between the two temperature difference measuring points.

In the exhaust gas flow measurement, which provides immediate information about the respective chimney draft, the temperature difference detection takes place according to a preferred embodiment of the invention using a thermopile of several series-connected high-temperature thermocouples, such as NiCr-Ni thermocouples or PtRh thermocouples. The temperature-influencing element is preferably a heating element, in particular a heating resistor whose heating power is adjustable. The temperature of the heating element is to be chosen so that it is greater than the temperature of the exhaust gases flowing to the measuring arrangement.

As already in DE 196 23 174 C1 for the general case proposed flow measurement, the heating element should be provided in the vicinity of the first temperature difference measuring point.

There are various possibilities of measuring operation. Thus, according to a first variant of the measuring operation, continuous continuous monitoring of the temperature difference between the two temperature difference measuring points takes place, wherein information about the flow behavior of the exhaust gas can be derived from changes in the temperature difference. In this case, the evaluation device of the control device assigned to the flow measuring device can be programmed to use the time that passes between cooling of the upstream measuring point and heating of the downstream measuring point as an indicator of the flow velocity as the flow velocity of the exhaust gas changes.

Furthermore, a dynamic measuring mode is possible in which e.g. the temporal temperature difference change measured by the switch-on of the heating element is measured and the measured values are evaluated to provide information about flow behavior. In this case, the heating element is preferably switched off between two measuring cycles, so that it assumes the normal exhaust gas temperature as the starting temperature for the next measuring cycle. The temperature difference changes to be measured can also be evaluated for flow evaluation.

The advantages of the invention are particularly useful in furnaces with a stove or a gas boiler in a living room, the inventively achievable exhaust gas technical and Zulufttechnische control or component control allows a largely optimized combustion operation. As mentioned above, come as actuators supply flaps, exhaust valves, draft regulator, hood switch, living room ventilation switch, smoke aspirators, etc. in question, with respective actual values of Abgasströmungsmessanordnungen, Zuluftströmungsmessanordnungen, an oven door switch, window switches, Zugregler-position sensors, exhaust valve position sensors, gas thermostats etc. monitored by the controller and can be included in the control processes.

The invention further relates to a method for detecting the exhaust gas flow in an exhaust pipe arrangement in a furnace, which is characterized in that by means of a temperature measuring arrangement, in particular thermocouple temperature measuring arrangement, a temperature difference in the flowing medium between at least two consecutive points in the flow path is detected and a temperature-influencing element in the form of a heating element and / or a cooling element is operated at a third point located between the two locations to produce the temperature difference, wherein the temperature difference measured values are evaluated to determine the direction and / or the strength of the exhaust gas flow.

According to a variant of the method, the temporal change of the temperature difference is measured as a step response to the switching on of the temperature influencing element, wherein information about the exhaust gas flow behavior is derived from the measured values.

The invention will be explained in more detail below with reference to FIG. 1.

To explain the concept of the invention of the air and / or exhaust gas control to optimize the combustion operation of a fireplace is shown in Fig. 1 in a simplified manner a furnace with a stove 1 as ambient air-dependent solid fuel fireplace in a living room 2. The stove 1 is connected via an exhaust pipe 3 to the chimney 5, wherein the exhaust pipe arrangement of the exhaust pipe 3 and the chimney 5, the exhaust gases resulting from the combustion operation of the stove 1 passes outside.

In the example of Fig. 1 is at the chimney outlet a smoke aspirator 7 is provided which can be activated with increased chimney draft requirement to suck the exhaust gases into the open. The chimney 7 may be for example a functioning according to the injector principle chimney in which a fan 9 promotes outside air into the annulus area 11, which then emerges upwardly out of the opening 13 of the chimney 7 together with the exhaust gases. The exhaust gases are discharged through the chimney extension pipe section 15 of the chimney 7. The stronger the parallel air flow generated by the blower 9, the greater the injector suction effect with which the exhaust gases are forcibly discharged. If the chimney draft, so the thermal buoyancy of the chimney 5 sufficient for optimum combustion operation of the furnace 1, the smoke extractor 7 may remain inactive.

To influence the chimney draft a controllable draft regulator 17 is provided, which is preferably a so-called combined secondary air device or a forced-controlled secondary air device. Depending on the position of the secondary air damper 19, more or less air can flow from the outside into the chimney 5 in order to limit the chimney draft. An electromotive actuator 21 serves to forcibly control the secondary air damper 19 as needed. The actuator is deactivated, so that the secondary air damper 19 can then operate in a known manner differential pressure controlled.

A controllable room ventilation device 23 serves, if necessary, to convey fresh air into the installation room of the stove 1.

If the window 25 is opened, fresh air can also pass through this window 25 in the installation room 2. To determine whether the window 25 is open or closed, is a window contact switch 27. In the installation room 2 of the stove 1 is also a cooker hood 29 which promotes air in the on state from the room 2 via the line 31 to the outside.

The exhaust pipe 3 is shown broken in two places, around an exhaust flap 33 and a flow measuring arrangement 35 (both shown in simplified form) to make recognizable. The position of the exhaust valve 33 is continuously controllable by means of the electromotive actuator 37. It could alternatively or additionally be provided between two end positions switchable exhaust flap.

The flow measuring arrangement 35 comprises at least one thermocouple with a thermocouple of two different electrical conductors (thermo legs 39, 41). The welding joint 43 of the two thermo legs 39, 41 forms a measuring point. At their ends remote from the welding point 43, the thermo legs 39, 41 are connected to measuring lines 49, 50, which are connected to the evaluation and control device 45. The connection point 47 between the thermo leg 39 and the connecting line 49 is located in the exhaust path from the stove 1 to the chimney 5 behind the measuring point 43 and forms a reference point for the detection of temperature differences between the two points 43 and 47. The evaluation and control device 45 evaluates the Thermocouple supplied thermoelectric voltage signal. In the immediate vicinity of the first measuring point 43 is a heating element 51, whose heating current is provided by the evaluation and control device 45.

If there is currently no exhaust gas flow in the exhaust pipe 3, the activation of the heating element 51 causes the measuring point 43 to undergo greater heating than the measuring point (reference) 47, wherein an equilibrium state of the temperature difference within a certain time after switching on the heating element 51 between positions 43 and 47. After the onset of the exhaust gas flow in the exhaust pipe 3 from the stove 1 toward the chimney 5, the thermal conditions on the flow measuring arrangement change to the fact that the upstream in the flow path measuring point 43 under the thermal influence of coming from the stove 1 exhaust gas and thus at least tends to the temperature assumes this exhaust gas. When the exhaust gas flows past the heating element 51 behind the point 43, it then comes for partially heating this exhaust gas, provided that the temperature of the heating element 51 is above the normal exhaust gas temperature. The heating element 51 thus generates a "thermal disturbance" in the exhaust gas flow, which is carried to the second point 47 and there gives rise to a temperature increase, which is reflected in the temperature difference signal of the thermocouple. The flow measuring arrangement 35 allows both the determination of the flow direction and the flow velocity, so that it can be used to check and monitor the train in the exhaust pipe arrangement 3, 5. As installation location for the flow measuring arrangement 35, the chimney 5 would also be suitable.

The flow and temperature information obtained by means of the flow measuring arrangement 35 can be used to control the components 7, 17, 23, 29 or / and 33 by means of a control device 53 in the sense of optimizing the burning operation of the stove 1.

The control device 53 is in signal transmission connection with actuators 10, 21, 24, 32, 37 of these components as well as with feedback sensors (not shown), which indicate the respective setting state of said components. Further, the controller 53 monitors the sigal of the window switch 27 and an oven door switch 55 indicating the closed state of the oven door. The signal transmission between control device 53 and the aforementioned actuators and feedback sensors can be done via wires or / and over radio links. Also a so-called power-line data transmission over the power supply network is conceivable within the scope of the invention.

At the operating device 59 of the control device 53, a respective operating mode of the stove 1 is preselected.

The control device 53 then carries out a status check of the furnace in accordance with the program sequence, the feedback sensors of the Components 7, 17, 23, 27, 29, 33, 55 are queried, whereupon the respective actuators 9, 21, 24, 32, 37 are driven as required by the selected program to affect the operating conditions for the chimney 1. In diesem Fall wird die Brennkraftmaschine an die Brennkraftmaschine zugeführt. If the controller 53 determines that the oven door 57 or / and the window 25 are to be opened or closed, it may issue a respective visual and / or audible indication to the operator.

During the burning operation, a tensile test is then regularly carried out, i. Measurement of the exhaust gas flow by means of the flow measuring arrangement 35 and a check of the furnace operating temperature and / or possibly the room temperature by means of the temperature sensors 60, 62, whose measurement signals are also taken into account by the control device 53. The room temperature sensor 62 may be e.g. to act a sensor for measuring the "sensed" temperature, as described in EP 1 121 609 B1.

In accordance with the selected program, the control device 53 changes the states of the components influencing the combustion operation by supplying corresponding signals to the adjusting devices. This can mean that the chimney 7 is switched on or off or possibly influenced in its suction power and / or that the operation of the room ventilation 23 is changed or turned off and / or the hood 29 is switched on or off or influenced in their suction power or / and the exhaust valve 33 is adjusted or / and the secondary air damper 19 is adjusted or / and a supply air flap 64 of the stove 1 is opened or closed by controlling its actuator 66.

The illustrated with reference to FIG. 1 embodiment of the invention thus represents a system which monitor the supply air and exhaust gas flow of the fireplace 1 and components that affect the combustion operation, can control to optimize the operation of the Feruerungsanlage as far as possible and to avoid malfunction.

The hearth is also a so-called pellet stove in question, which is set up for burning solid fuel pellets.

The optimization of the combustion operation and the improvement of the efficiency of the fireplace using the concept of the invention leads to fuel savings and to minimize the exhaust pollution of the environment. Furnace commissioning can be simplified. It is also possible to include several hearths in the furnace of the invention, e.g. a gas boiler and a woodburning stove, both attached to a chimney. In particular, using Zuluftsensoren and supply air dampers can be made a degree of efficiency regarding the furnace operation and an efficiency indicator can be provided.

Tension regulators can be used to protect the fireplace from sooting.

Particularly in the case of room air-independent fireplaces with combustion air supply from the outside, it is advisable to provide a flow measuring arrangement and a controllable inlet air flap in the supply air duct and to include it in the control process.

For security reasons, the following aspects should be considered. When the system is turned on, a self-test should be performed to ensure that the components function correctly. In the event of a power failure or sensor defect, all actuators should remain in the current position and not automatically fall into the closed position.

Safety-related parameters, such as the level of low temperature, should only be changed by authorized persons, for example after entering a four- to six-digit password. At low temperature, an optical or / and audible alarm signal to be acknowledged should be output by the control device.

In a multi-firing system with multiple hearths on a common fireplace and e.g. A common smoke extractor should be blocked if the chimney draft is too low.

The control concept of the invention should further include a function for safe "shutdown" of the fireplace.

Claims (18)

Furnace with a hearth (1), an exhaust pipe arrangement (3, 5) connected to the hearth (1) for discharging the exhaust gases produced during the burning process in the hearth (1), a controllable device (7, 17, 23, 29, 33, 64) for influencing the operating conditions of the fireplace (1), and a control device (53) for controlling the device (7, 17, 23, 29, 33, 64) for influencing the operating conditions of the fireplace (1),
characterized in that
a flow measuring arrangement (35) is provided and adapted to detect the exhaust gas flow in the exhaust pipe arrangement (3, 5) by measurement,
wherein the control device (53) is adapted to control the device for influencing the operating conditions of the fireplace in accordance with measuring effects of the flow measuring arrangement (35). Furnace according to claim 1, characterized in that it comprises a Verbrennungsluftzuführungsanordung and a flow measuring arrangement for detecting the combustion air flow in the Verbrennungsluftzuführungsanordung. Furnace according to claim 1 or 2, characterized in that the respective flow measuring arrangement (35) comprises a temperature measuring arrangement for detecting a temperature difference in the flowing medium between two consecutive points in the flow path (43, 47) - and at least one between the two points (43, 47) provided temperature influencing element (51). Furnace according to claim 3, characterized in that the temperature-influencing element (51) is a heating element or a cooling element. Furnace according to claim 3 or 4, characterized in that the temperature influencing element (51) to a first (43) of the two points (43, 47) has a smaller distance than to the other point (47). Furnace according to claim 5, characterized in that the temperature-influencing element (51) is arranged in close proximity to the first location (43). Furnace according to one of claims 3 to 6, characterized in that the temperature of the temperature-influencing element (51) is adjustable. Furnace according to claim 7, characterized by a control device for controlling the operating energy of the temperature-influencing element. Furnace according to at least one of the preceding claims 3 to 8, characterized in that the temperature measuring arrangement comprises at least one thermocouple. Furnace according to at least one of the preceding claims, characterized in that the fireplace (1) is a solid fuel stove, in particular a stove. Furnace according to at least one of claims 1 to 9, characterized in that the fireplace is a guest device. Furnace according to at least one of claims 1 to 9, characterized in that the fireplace is a boiler with burner. Furnace according to at least one of the preceding claims, characterized in that the controllable device (7, 17, 23, 29, 33, 64) for influencing the operating conditions of the fireplace (1) at least one in or directly on the exhaust pipe arrangement (3, 5) provided - and the exhaust gas flow affecting device (7, 17, 33). Furnace according to claim 13, characterized in that the device influencing the exhaust gas stream comprises a controllable draft regulator (17) or / and a controllable exhaust gas flap (33) or / and a controllable smoke extractor (7). Furnace according to at least one of the preceding claims, characterized in that the controllable device (7, 17, 23, 29, 33, 64) for influencing the operating conditions of the fireplace (1) at least one influencing the combustion air supply for the fireplace (1) device ( 24, 32, 64). Furnace according to claim 15, characterized in that the combustion air supply for the fireplace (1) influencing device (24, 32, 64) at least one controllable combustion air damper (64) and / or a controllable switching device (32) for a cooker hood (29) or / and a controllable switching device (24) for a living room ventilation device (23) and / or a controllable switching device for a combustion air blower. A method for detecting the exhaust gas flow in an exhaust pipe arrangement of a furnace, characterized in that by means of a temperature measuring arrangement , a temperature difference in the flowing medium is detected between two consecutive points in the flow path and at a position lying between the two bodies a temperature influencing element in the form of a heating element and / or a cooling element is operated to generate the temperature difference, the temperature difference measured values for determining the direction or / and the strength of the exhaust stream are evaluated. A method according to claim 17, characterized in that for the temperature difference detection at least one thermocouple is used as a sensor in the exhaust stream.

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