Heater device and method for operating a heater device

Abstract

A heater device including at least one control and/or regulating unit, which is provided to set an air ratio of a combustion process to a setpoint air ratio. It is provided that the control and/or regulating unit is provided to ascertain a power correction factor in at least one operating state and take it into consideration in the setting of the air ratio.

Claims

1. A heater device, comprising: a heating unit having a heating module, wherein the heating module includes a first metering unit to deliver and/or regulate a combustion air flow and further includes a second metering unit having a control valve to deliver and/or regulate a gas, wherein the first metering unit is coupled to a first feed line for combustion air, and wherein the second metering unit is coupled to a second feed line for fuel; at least one control and/or regulating unit configured to set an air ratio of a combustion process to a setpoint air ratio; a plurality of pre-calibrated sensors, including at least a flow sensor, an immersion sensor, a power sensor, and a temperature sensor; and a discharge unit; wherein the control and/or regulating unit is configured to ascertain a power correction factor in at least one operating state and take the ascertained power correction factor into consideration in the setting of the air ratio, wherein the heating module includes a main burner, which is coupled via the first metering unit to the first feed line for the combustion air, wherein the main burner is configured to burn a mixture of the combustion air and the fuel in at least one operating state, wherein the heating unit includes a heat exchanger situated adjacent to heat provided by the main burner, wherein the heat exchanger includes a feed line for an unheated fluid and an outlet for a heated fluid, wherein the heating unit, which is coupled to an exhaust gas outlet, includes an exhaust gas module to discharge exhaust gases via the exhaust gas outlet, wherein the discharge unit is configured to discharge the heated fluid from the heat exchanger and/or the heater, and includes a fluid outlet, which is connected to an outlet of the heat exchanger via a further fluid connection, and wherein the control and/or regulating unit is coupled to the first metering unit and the second metering unit and to the plurality of sensors.

2. The heater device as recited in claim 1, wherein the power correction factor corresponds to a quotient of a required input power and an actual input power.

3. The heater device as recited in claim 2, wherein the control and/or regulating unit is configured to ascertain at least one of the required input power and the actual input power, based on at least one of: (i) a requested output power, and (ii) an actual output power and a thermal efficiency.

4. The heater device as recited in claim 3, wherein the control and/or regulating unit is configured to ascertain at least one of the requested output power and the actual output power, based on a temperature of at least one of a fluid and a fluid flow.

5. The heater device as recited in claim 1, wherein the control and/or regulating unit is configured to ascertain the power correction factor in the at least one operating state at time intervals of no more than 30 s.

6. The heater device as recited in claim 1, wherein the control and/or regulating unit is configured to take at least the power correction factor into consideration for the determination of a required fuel flow.

7. The heater device as recited in claim 1, wherein the control and/or regulating unit is configured to ascertain an actual combustion air flow in at least one operating state and take the ascertained actual combustion air flow into consideration for the determination of a required fuel flow.

8. The heater device as recited in claim 1, wherein the control and/or regulating unit is configured to set a combustion air flow and a fuel flow independently of one another.

9. A continuous flow heater, comprising: at least one heater device having at least one control and/or regulating unit configured to set an air ratio of a combustion process to a setpoint air ratio; wherein the control and/or regulating unit is configured to ascertain a power correction factor in at least one operating state and take the ascertained power correction factor into consideration in the setting of the air ratio, and wherein the heater device further includes: a heating unit having a heating module, wherein the heating module includes a first metering unit to deliver and/or regulate a combustion air flow and further includes a second metering unit having a control valve to deliver and/or regulate a gas, wherein the first metering unit is coupled to a first feed line for combustion air, and wherein the second metering unit is coupled to a second feed line for fuel; a plurality of pre-calibrated sensors, including at least a flow sensor, an immersion sensor, a power sensor, and a temperature sensor; and a discharge unit; wherein the control and/or regulating unit is configured to ascertain a power correction factor in at least one operating state and take the ascertained power correction factor into consideration in the setting of the air ratio, wherein the heating module includes a main burner, which is coupled via the first metering unit to the first feed line for the combustion air, wherein the main burner is configured to burn a mixture of the combustion air and the fuel in at least one operating state, wherein the heating unit includes a heat exchanger situated adjacent to heat provided by the main burner, wherein the heat exchanger includes a feed line for an unheated fluid and an outlet for a heated fluid, wherein the heating unit, which is coupled to an exhaust gas outlet, includes an exhaust gas module to discharge exhaust gases via the exhaust gas outlet, wherein the discharge unit is configured to discharge the heated fluid from the heat exchanger and/or the heater, and includes a fluid outlet, which is connected to an outlet of the heat exchanger via a further fluid connection, and wherein the control and/or regulating unit is coupled to the first metering unit and the second metering unit and to the plurality of sensors.

10. A method for operating a heater device, the method comprising: setting an air ratio for a combustion process to a setpoint air ratio; and ascertaining, in at least one operating state, a power correction factor which is taken into consideration in the setting of the air ratio; wherein the heater device includes: a heating unit having a heating module, wherein the heating module includes a first metering unit to deliver and/or regulate a combustion air flow and further includes a second metering unit having a control valve to deliver and/or regulate a gas, wherein the first metering unit is coupled to a first feed line for combustion air, and wherein the second metering unit is coupled to a second feed line for fuel; at least one control and/or regulating unit configured for the setting of the air ratio for the combustion process to the setpoint air ratio; a plurality of pre-calibrated sensors, including at least a flow sensor, an immersion sensor, a power sensor, and a temperature sensor; and a discharge unit; wherein the control and/or regulating unit is configured to ascertain a power correction factor in at least one operating state and take the ascertained power correction factor into consideration in the setting of the air ratio, wherein the heating module includes a main burner, which is coupled via the first metering unit to the first feed line for the combustion air, wherein the main burner is configured to burn a mixture of the combustion air and the fuel in at least one operating state, wherein the heating unit includes a heat exchanger situated adjacent to heat provided by the main burner, wherein the heat exchanger includes a feed line for an unheated fluid and an outlet for a heated fluid, wherein the heating unit, which is coupled to an exhaust gas outlet, includes an exhaust gas module to discharge exhaust gases via the exhaust gas outlet, wherein the discharge unit is configured to discharge the heated fluid from the heat exchanger and/or the heater, and includes a fluid outlet, which is connected to an outlet of the heat exchanger via a further fluid connection, and wherein the control and/or regulating unit is coupled to the first metering unit and the second metering unit and to the plurality of sensors.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Further advantages of the present invention may be derived from the description below of the figures. The figures show one exemplary embodiment of the present invention. The figures and the description include numerous features and combinations. Those skilled in the art will advantageously also consider the features individually and combine them into useful further combinations.

(2) FIG. 1 shows a schematic block diagram of a heater designed as a continuous flow heater including a heater device.

(3) FIG. 2 shows a block diagram for an exemplary operation of the heater device.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

(4) FIG. 1 shows an exemplary heater 12 in a schematic block diagram representation. Heater 12 is designed as a continuous flow heater in the present case. Alternatively, it is possible that the heater is designed as a boiler. Heater 12 includes a heater device.

(5) The heater device includes a heating unit 14. Heating unit 14 is provided to heat a fluid. In the present case, heating unit 14 is provided to heat water. For this purpose, heating unit 14 includes a heating module 16. Heating module 16 is designed as a gas burner module. Alternatively, however, it is also possible that a heating unit is provided to heat a different fluid, such as a cooling medium and/or a heating medium.

(6) Heating module 16 includes a first metering unit 18 for combustion air. First metering unit 18 is designed as a variable-speed blower. First metering unit 18 is provided to deliver and/or to regulate a combustion air flow. For this purpose, first metering unit 18 is connected to a first feed line 20 for combustion air. Moreover, heating module 16 includes a second metering unit 22 for fuel. Second metering unit 22 is designed as a variable-throughput and electronic fuel valve. In the present case, second metering unit 22 is designed as a control valve, in particular as an oscillator coil-modulated flow control valve. Second metering unit 22 is provided to deliver and/or to regulate a fuel flow. In the present case, second metering unit 22 is provided to deliver and/or to regulate a gas. For this purpose, second metering unit 22 is connected to a second feed line 24 for fuel.

(7) Heating module 16 furthermore includes a main burner 26. Main burner 26 is designed as a gas burner in the present case. Main burner 26 is connected via first metering unit 18 to first feed line 20 for combustion air. Moreover, main burner 26 is connected via second metering unit 22 to second feed line 24 for fuel. Main burner 26 is provided to burn a mixture made up of a combustion air and a fuel in at least one operating state. Main burner 26 is provided to generate a heating flame. Additionally, a heating module may include a pilot burner, which in particular is provided to provide a pilot flame for a main burner. Moreover, it is possible to use spark ignition, for example, instead of a pilot burner.

(8) Furthermore, heating unit 14 includes a heat exchanger 28. Heat exchanger 28 is situated in the immediate surroundings of the heating flame. Heat exchanger 28 is provided to transmit thermal energy from heating module 16 to the fluid. For this purpose, heat exchanger 28 includes a feed line 30 for an unheated fluid, in particular water, and an outlet 32 for a heated fluid, in particular water.

(9) Additionally, heating unit 14 includes an exhaust gas module 34. Exhaust gas module 34 is designed as a flue. Exhaust gas module 34 is provided to discharge exhaust gases. For this purpose, exhaust gas module 34 is connected to an exhaust gas outlet 36.

(10) Moreover, the heater device includes a feed unit 38. In the present case, feed unit 38 is provided to feed the unheated fluid to heat exchanger 28 and/or to heater 12. For this purpose, feed unit 38 includes a fluid inlet 40. Fluid inlet 40 is connected to feed line 30 of heat exchanger 28 via a fluid connection.

(11) Furthermore, the heater device includes a discharge unit 42. Discharge unit 42 is provided to discharge the heated fluid from heat exchanger 28 and/or heater 12. For this purpose, discharge unit 42 includes a fluid outlet 44. Fluid outlet 44 is connected to outlet 32 of heat exchanger 28 via a further fluid connection.

(12) Heater device furthermore includes multiple sensors 46, 48, 50, 52, 54. In the present case, heater device includes at least seven sensors 46, 48, 50, 52, 54. Sensors 46, 48, 50, 52, 54 are precalibrated to ensure in particular a high accuracy of the ascertained values. A recalibration and/or readjustment of sensors 46, 48, 50, 52, 54 during operation is dispensed with. A first sensor 46 is designed as a flow rate sensor. First sensor 46 is designed as a vortex flow meter. First sensor 46 is provided to detect a fluid flow. A second sensor 48 is designed as a first temperature sensor. Second sensor 48 is designed as an NTC immersion sensor. Second sensor 48 is provided to detect a fluid temperature. Second sensor 48 is provided to detect a temperature of the fluid immediately downstream from fluid inlet 40 and/or immediately upstream from feed line 30 of heat exchanger 28. A third sensor 50 is designed as a second temperature sensor. Third sensor 50 is designed as an NTC immersion sensor. Third sensor 50 is provided to detect a fluid temperature. Third sensor 50 is provided to detect a temperature of the fluid immediately downstream from outlet 32 of heat exchanger 28 and/or immediately upstream from fluid outlet 44. A fourth sensor 52 is designed as a third temperature sensor. Fourth sensor 52 is provided to detect a temperature of the combustion air, in particular of the combustion air flow. Fourth sensor 52 is provided to detect a temperature of the combustion air, in particular of the combustion air flow, immediately downstream from first metering unit 18 and/or immediately upstream from main burner 26. A fifth sensor 54 is designed as a fourth temperature sensor. Fifth sensor 54 is designed as an exhaust gas temperature sensor. Fifth sensor 54 is provided to detect a temperature of the burned mixture made up of the combustion air and the fuel. Fifth sensor 54 is provided to detect a temperature of the burned mixture immediately downstream from main burner 26 and/or immediately upstream from exhaust gas outlet 36. A sixth sensor (not shown) is designed as a power sensor. The sixth sensor is provided to detect a power consumption of first metering unit 18. A seventh sensor (not shown) is designed as a rotation sensor. For example, the seventh sensor is designed as a magnetic sensor. The seventh sensor is provided to detect a rotational speed of first metering unit 18. The rotational speed is a variable which reflects the revolutions per unit of time, for example the revolutions per minute. As an alternative and/or in addition, it is possible that a heater device includes further sensors, such as at least one pressure sensor and/or at least one temperature sensor for a fuel and/or for a mixture made up of a combustion air and a fuel.

(13) Furthermore, the heater device includes a control and/or regulating unit 10. Control and/or regulating unit 10 is provided to control an operation of the heater device. For this purpose, control and/or regulating unit 10 includes a processing unit, a memory unit, and an operating program which is stored in the memory unit and provided to be executed by the processing unit. Moreover, control and/or regulating unit 10 is provided to set and/or provide a requested heating power. For this purpose, control and/or regulating unit 10 has an electrical connection to first metering unit 18 and second metering unit 22. In the present case, control and/or regulating unit 10 is provided to set the combustion air flow and the fuel flow independently of one another with the aid of first metering unit 18 and second metering unit 22. Moreover, control and/or regulating unit 10 has an electrical connection to sensors 46, 48, 50, 52, 54.

(14) Control and/or regulating unit 10 is provided to set an air ratio .sub.c of the combustion process to a setpoint air ratio .sub.d. Furthermore, control and/or regulating unit 10 is provided to ascertain a power correction factor C.sub.F in at least one operating state and take it into consideration in a setting of air ratio .sub.c to setpoint air ratio .sub.d.

(15) The equations required for this purpose, which are in particular stored in the memory unit of control and/or regulating unit 10, are summarized hereafter, while an exemplary operation is described below with reference to FIG. 2.

(16) Control and/or regulating unit 10 is provided to set air ratio .sub.c to setpoint air ratio .sub.d as a function of the combustion air flow, in particular of a required combustion air flow Q.sub.air,d and/or an actual combustion air flow Q.sub.gas,c and the fuel flow, in particular of a required fuel flow Q.sub.gas,d and/or an actual fuel flow Q.sub.gas, c. The variables are correlated with one another as follows:
.sub.i=Q.sub.air,i/Q.sub.gas,i(1)

(17) Moreover, control and/or regulating unit 10 is provided to ascertain an output power, in particular a requested output power P.sub.out,d and/or an actual output power P.sub.out,c, based on a temperature of the fluid, in particular a requested output temperature T.sub.out,c of the fluid, an actual output temperature T.sub.out,c of the fluid ascertained with the aid of third sensor 50 and/or an input temperature T.sub.in of the fluid ascertained with the aid of second sensor 48, and a fluid flow q.sub.m. For this applies:
P.sub.out,i=q.sub.m.Math.c.sub.p.Math.(T.sub.out,iT.sub.in)(2)

(18) The fluid flow q.sub.m corresponds to a flow rate of the fluid ascertained with the aid of first sensor 46, and c.sub.p corresponds to a calorific value of the fluid.

(19) Furthermore, control and/or regulating unit 10 is provided to ascertain an input power, in particular a required input power P.sub.in,d and/or an actual input power P.sub.in,c, based on the output power, in particular the requested output power P.sub.out,d and/or the actual output power P.sub.out,c, and a thermal efficiency 11 of heating module 16. For this applies:
P.sub.in,i=P.sub.out,i(3)

(20) In the present case, control and/or regulating unit 10 is provided to ascertain thermal efficiency at least based on an input temperature of the combustion air ascertained with the aid of fourth sensor 52 and an exhaust gas temperature ascertained with the aid of fifth sensor 54, by which in particular possible signs of aging of heating module 16 may be considered. Since such an ascertainment of thermal efficiency in particular is only valid in a slightly lean mixture range (.sub.c>1) of the mixture made up of the combustion air and the fuel, control and/or regulating unit 10 is furthermore provided to ascertain a mixture range in which the combustion takes place. Control and/or regulating unit 10 takes advantage of the property that in the lean mixture range an increase in the fuel flow, at a constant combustion air flow, results in an increase in the output power, while this is not the case in a rich mixture range (.sub.c<1). Moreover, control and/or regulating unit 10 is provided to ascertain air ratio .sub.c based on the exhaust gas temperature.

(21) Additionally, the following relationship applies for required input power P.sub.in,d:
P.sub.in,d=Q.sub.ges,d.Math.P.sub.1=C.sub.n.Math.W.sub.i(2.Math..sub.p){circumflex over ()}()=C.sub.n.Math.W.sub.i,ref.Math.C.sub.F.Math.(2.Math..sub.p){circumflex over ()}()(4)
where
Q.sub.gas,d=C.sub.n.Math.[(2.Math..sub.p)/]{circumflex over ()}()(5)
P.sub.in,d/P.sub.in,c=C.sub.F(6)
P.sub.in,c(gas1)/P.sub.in,c(gas2)=W.sub.i(gas1)/W.sub.i(gas2)(7)
and
.sub.p=p.sub.Bp.sub.air
P.sub.i corresponds to a calorific value of heating unit 14, C.sub.n to a flow rate coefficient of a main burner nozzle, W.sub.i to a Wobbe index of a present fuel, W.sub.i,ref to a Wobbe index of a reference fuel, C.sub.F to the power correction factor, to a density of the fuel, p.sub.B to a pressure of the main burner and/or a back pressure of the main burner nozzle, and p.sub.air to a pressure of the combustion air and/or a counter pressure of the main burner nozzle. Moreover, power correction factor C.sub.F corresponds to a quotient of required input power P.sub.in,d and actual input power P.sub.in,c. If main burner 26 is operated with the reference fuel, power correction factor C.sub.F is indicated by the value 1. In the present case, power correction factor C.sub.F thus corresponds to a factor dependent on the present fuel.

(22) Moreover, in the present case control and/or regulating unit 10 is provided to determine an air ratio correction factor f.sub. dependent on power correction factor C.sub.F, and to take it into consideration in the determination of air ratio .sub.c and/or setpoint air ratio .sub.d, in particular in equation (1). A corrected equation (1) thus reads:
.sub.i=f.sub.(C.sub.F).Math.Q.sub.air,i/Q.sub.gas,i(9)

(23) A difference between equation (1) and equation (9), however, is less than 5%, so that a determination of air ratio correction factor f.sub. may also be dispensed with.

(24) If a heated fluid, and thus a certain output temperature T.sub.out,d, is requested by control and/or regulating unit 10 and/or by a user, control and/or regulating unit 10 is provided to ascertain required combustion air flow Q.sub.air,d and required fuel air flow Q.sub.gas,d for requested output power P.sub.out,d, and in particular to accordingly adapt actual combustion air flow Q.sub.air,c and actual fuel flow Q.sub.gas,c. The individual operating steps for this purpose are illustrated in FIG. 2 based on an exemplary block diagram, a sequence of the individual operating steps being at least partially variable.

(25) In an operating step 56, control and/or regulating unit 10 is provided to ascertain and read in required measured values with the aid of sensors 46, 48, 50, 52, 54.

(26) In an operating step 58, control and/or regulating unit 10 is provided to determine requested output power P.sub.out,d based on requested output temperature T.sub.out,d, and in particular using equation (2).

(27) In an operating step 60, control and/or regulating unit 10 is provided to ascertain required combustion air flow Q.sub.air,d based on requested output power P.sub.out,d, and in particular using equation (9) or alternatively equation (1), and to accordingly readjust first metering unit 18.

(28) In an operating step 62, control and/or regulating unit 10 is provided to ascertain required input power P.sub.in,d based on requested output power P.sub.out,d, based on thermal efficiency , and in particular using equation (3).

(29) In an operating step 64, control and/or regulating unit 10 is provided to determine an actual combustion air flow Q.sub.air,c. In the present case, control and/or regulating unit 10 is provided to ascertain actual combustion air flow Q.sub.air,c based on a rotational speed of metering unit 18 ascertained with the aid of the seventh sensor and a characteristics field stored in the memory unit of control and/or regulating unit 10. Alternatively, however, it is also possible that a control and/or regulating unit 10 is provided to ascertain an actual combustion air flow based on a power consumption of first metering unit 18 ascertained with the aid of the sixth sensor, a rotational speed of first metering unit 18, which is known to control and/or regulating unit 10 based on an activation of first metering unit 18, and a characteristics field stored in the memory unit of control and/or regulating unit 10. Such a method is described in German Patent Application No. DE 10 2012 016 606 A1, for example. Alternatively, however, it is also possible that a control and/or regulating unit is provided to ascertain an actual combustion air flow with the aid of at least one flow rate sensor, at least one mass flow sensor and/or with the aid of a differential pressure measurement. Moreover, control and/or regulating unit 10 is provided to infer the pressure of combustion air p.sub.air based on actual combustion air flow Q.sub.air,c.

(30) In an operating step 66, control and/or regulating unit 10 is provided to ascertain the pressure of main burner p.sub.B based on required input power P.sub.in,d and the pressure of combustion air p.sub.air, and in particular using equations (4) and (8). Subsequently, control and/or regulating unit 10 is provided to ascertain required fuel flow Q.sub.gas,d, in particular based on equation (5), and to accordingly readjust second metering unit 22. Accordingly, control and/or regulating unit 10 is provided to take actual combustion air flow Q.sub.air,c into consideration for the determination of required fuel flow Q.sub.gas,d.

(31) Moreover, control and/or regulating unit 10 is provided to take power correction factor C.sub.F into consideration for the determination of required fuel flow Q.sub.gas,d. In the present case, control and/or regulating unit 10 is provided to ascertain power correction factor C.sub.F in an operating step 68 and to take it into consideration in operating step 62.

(32) To ascertain power correction factor C.sub.F, control and/or regulating unit 10 is provided to determine actual output power P.sub.out,c based on actual output temperature T.sub.out,c, and in particular using equation (2). Moreover, control and/or regulating unit 10 is provided to ascertain actual input power P.sub.in,c based on actual output power P.sub.out,c, and in particular using equation (3). Power correction factor C.sub.F then results as the ratio between required input power P.sub.in,d and actual input power P.sub.in,c, and in particular based on equation (6).

(33) Control and/or regulating unit 10 is provided to adapt required input power P.sub.in,d with the aid of correction factor C.sub.F. For this purpose, control and/or regulating unit 10 is provided to ascertain power correction factor C.sub.F in the at least one operating state at time intervals of 0.5 s, and to at least essentially continuously adapt required input power P.sub.in,d with the aid of power correction factor C.sub.F. For this applies:
C.sub.F(n)=P.sub.in,d/P.sub.in,c.Math.C.sub.F(n1)(10)

(34) C.sub.F(n1) corresponds to a power correction factor C.sub.F at point in time n1, and C.sub.F(n) corresponds to a power correction factor C.sub.F at point in time n. In the present case, points in time n and n1 have a difference of 0.5 s. In this way, control and/or regulating unit 10 is able to infer a composition and/or a type of the fuel and, in the event of a change in the composition and/or the type of fuel, to adapt first metering unit 18 and/or second metering unit 22 relatively quickly and automatically to these new conditions.