ARRANGEMENT AND METHOD FOR OPERATING A HEATING APPLIANCE

Description

[0001] The invention relates to an arrangement and a method for the efficient operation of a heating appliance. This concerns systems for heating water and, more generally, heating appliances for heating buildings and / or providing hot water.

[0002] Heating systems primarily powered by a single fuel (gas, oil, hydrogen, etc.) consume not only energy in the form of fuel but also electrical energy to drive components such as fans, circulation pumps, electronic measuring and control devices, and the like. Generally, efforts are made to minimize electrical power consumption. Furthermore, the number of components in a heating system is kept to a minimum, both to reduce costs and to avoid unnecessary system complexity. There is also a constant drive to minimize system failure while simultaneously ensuring safe and robust operation.

[0003] Modern heating appliances typically contain a blower (also called a fan) that draws ambient air to a burner during operation. Fuel, in a quantity suitable for combustion, is mixed into the resulting airflow before it reaches the burner. The resulting mixture is then fed by the burner into a combustion chamber where it is burned. Exhaust gases are discharged via a flue system. This process involves overcoming considerable flow resistance, particularly at the transition from the burner to the combustion chamber, where the mixture is forced through numerous very small openings. Depending on the type of fuel used, opening diameters of 2 to less than 0.8 mm (millimeters) are employed; even smaller openings may be used with hydrogen as fuel. This means that higher blower outputs and consequently higher electricity consumption are required when hydrogen is used as the fuel gas or as an additive to the fuel gas.The entire airflow from an air inlet back into the environment via the exhaust system is maintained by the blower, which is why it consumes a significant portion of the electrical energy required to operate the heater. The blower must be able to operate (modulate) at different power levels depending on the heater's required output and other ambient conditions. However, each blower is designed for a specific optimal power level at which it operates most efficiently. Consequently, at higher or lower power levels, it consumes more electrical energy per unit of blower power than blowers specifically designed for those power levels. An arrangement with the design features of the preamble of claim 1 is known from EP 0071416 A2.

[0004] The object of the present invention is to at least partially solve the problems described with reference to the prior art and, in particular, to create an arrangement and a method for operating a heating device at different power levels with the lowest possible consumption of electrical energy and reliable and robust modulation over a wide power range.

[0005] To solve this problem, an arrangement, a method, and a computer program product according to the independent claims are provided. Advantageous embodiments and further developments of the invention are specified in the respective dependent claims. The description, particularly in conjunction with the drawing, illustrates the invention and provides further exemplary embodiments.

[0006] In the arrangement used to solve the problem, for operating a heating appliance in which hydrogen or a fuel gas containing hydrogen is mixed with an air stream as fuel, the resulting mixture is burned in a combustion chamber, and the resulting combustion gases are discharged via an exhaust system, the heating appliance has a first blower and a second blower connected in series. These blowers are connected to a control unit via separate (electrical or electronic) control lines and can be controlled individually. The control unit is designed to distribute the blower power required for a predefined heating appliance output between the first and second blowers, thus minimizing power consumption. At least one of the blowers has a maximum blower power that is lower than the total blower power required for the heating appliance's maximum output.

[0007] Although this makes the heating unit somewhat more complex and two fans cost more to manufacture than one, the availability of the unit increases significantly. If one fan fails, the other can at least partially take over its function, preventing the heating unit from failing completely, as would be the case with only one fan. Furthermore, with proper design of the two fans, the additional manufacturing costs are more than offset by lower operating costs. This is because heating units can generally be operated at a wide range of power outputs, and in practice, this is indeed the case. It is by no means always possible to predict which specific power output will be required most frequently.For each heating appliance's output, a specific volume flow of air, and therefore a corresponding total fan output (volume flow), is required. However, a fan can only be optimized for one specific fan output. This fan output is called the design point. The further the fan is operated from the design point, the less efficiently it works, and the less fan output is available per unit of electrical input (power consumption). However, if two fans are used, additional possibilities arise to reduce power consumption at a given required total fan output. This is particularly important for heating appliances powered by hydrogen or hydrogen-containing fuel gas, which typically require higher fan outputs.

[0008] The spatial arrangement of the two blowers is not fundamentally important; however, the first and second blowers are preferably arranged upstream of the combustion chamber, respectively, in the direction of airflow. This arrangement results in low temperatures in the blowers and good accessibility. The point at which a fuel (fuel gas or oil) is added is also irrelevant for the present invention. The second blower can be installed at a suitable location in a conventional system. It is also possible, in principle, to provide further blowers or connect them in series to extend this concept.

[0009] Alternatively, the second fan (or both fans) can also be located downstream of the combustion chamber in the exhaust system. In this case, no space is required upstream of the combustion chamber; however, the temperatures in the second fan are somewhat higher than in the first fan, which is not necessarily a disadvantage.

[0010] At least one of the fans has a maximum fan output that is lower than the total fan output required for the heater to operate at maximum power. Assuming that the heater's maximum output (as well as its minimum output) is only rarely required, it is advantageous to design at least one, preferably both, fans with a lower maximum fan output, for example, both with half the maximum fan output, so that together they can deliver the maximum required output. The design points of both fans would then each be somewhere below half the fan output required for the heater's maximum output. This allows for an energy-efficient distribution of the corresponding fan output across both fans for a wide range of heater outputs and permits a broad modulation range for the fan output.

[0011] Both blowers have different operating points where they exhibit the lowest energy consumption per unit of blower power. This variant is particularly advantageous when the heating appliance is primarily operated at very specific power levels that are unevenly distributed between minimum and maximum power, especially mainly in the lower or upper half of the power range.

[0012] The solution to the problem is also particularly aided if the control unit is set up to distribute the blower power required for a given output of the heating device between the first and second blowers in such a way as to result in the lowest possible power consumption.

[0013] In a corresponding method for operating a heating appliance in which hydrogen or a hydrogen-containing fuel gas is mixed with an air stream and which is equipped with a first blower and a second blower connected in series, only one or both blowers are operated, depending on the current output required by the heating appliance. For low outputs, preferably only one blower is used, but as soon as this blower operates above its design point due to increasing output demand, it can be advantageous to activate the second blower and then distribute the output. If the blowers have different design points, it can even be advantageous to switch from operating only one blower to operating only the other blower when the heating appliance's output changes (by simultaneously increasing the speed of the second blower and decreasing the speed of the first).In particular, when operating only one fan, the one whose design point is closest to the required fan output for the currently required output of the heating device is selected.

[0014] Furthermore, when both fans are operating, the total fan output is distributed between the first and second fans in such a way that the power consumption for this total fan output is minimized. This is one of the particular advantages, because it is almost always possible to operate closer to the design points of both fans (and thus save energy) than would be possible with a single fan (and a single design point).

[0015] The control unit advantageously stores calibration data that specifies the optimal distribution of fan power between the first and second fans for any given total fan output. This allows the optimal distribution of fan power between the two fans for a given heating unit output to be determined and set without further measurements or adjustments.

[0016] Alternatively or additionally (e.g., if the characteristics of the fans change over time), the current power consumption of both fans is fed to the control unit. The control unit then determines and sets a minimum power consumption by adjusting the power distribution between the two fans. Such determination and adjustment can be achieved, for example, by slightly altering the distribution in one direction. If power consumption increases as a result, the distribution is adjusted in the other direction. If it also increases in that direction, the initial setting was optimal. If power consumption decreases in one direction, adjustments are made in that direction until it increases again. In this way, a minimum can be found.

[0017] Another aspect concerns a computer program product comprising commands that cause the described arrangement to execute the described procedure. The described distribution of fan power to two fans requires a program and data, both of which may need to be updated occasionally. The computer program product can be installed, at least partially, in the control unit.

[0018] The explanations of the procedure can be used to further characterize the arrangement, and vice versa. The arrangement can also be set up in such a way that the procedure is carried out using it.

[0019] A schematic embodiment of the invention, to which it is not limited, and the functioning of the method will now be explained in more detail with reference to the drawing. It illustrates: Fig. 1: A heating device with two fans connected to a control and regulation unit.

[0020] Fig. 1Figure 1 schematically shows a heating appliance 1, which is supplied with ambient air via an air inlet 2 and with fuel, in particular fuel gas from a supply network, via a fuel inlet 3. Fuel is mixed with the air via a fuel valve 5, and the resulting mixture is fed to a burner 8 by means of a first fan 6 and a second fan 7. The burner 8 distributes the mixture in the combustion chamber 9, where it is burned. The resulting combustion gases are fed to an exhaust system 10 and from there released into the environment. A control unit 4 controls the fuel valve 5 and the fans 6 and 7 via control lines 11. In the present embodiment, the first fan 6 is arranged upstream of the burner 8 and the second fan 7 downstream of the burner 8 in the exhaust system 10. However, it is also possible to arrange both fans 6 and 7 upstream of the burner 8 or both in the exhaust system 10.The arrangement shown allows for a wider range of fan output, and thus a larger output range for the heater 1, to be covered efficiently and robustly than would be possible with a single fan. If only one of the fans 6, 7 is in operation, it can be operated safely and robustly at a minimum output that a larger fan could not achieve stably. Nevertheless, both fans 6, 7 together can achieve the same maximum output as a larger fan. Therefore, the described arrangement allows for robust and reliable modulation over a wide range. In addition, as described above, it is possible, within broad limits, to design the power distribution between the two fans 6, 7 in such a way as to minimize power consumption. The control of the fans 6, 7 can be designed in various preferred ways: . 1. The first fan 6 can be activated at the lowest output of the heater 1 up to a predefined partial load point. Only then is the second fan 7 activated from this partial load point up to full load. 2. The first fan 6 can be activated at the lowest output of the heater 1 up to a predefined partial load point. Even while this partial load point is being reached and the maximum output of the first fan 6 has not yet been reached, the second fan 7 is activated up to full load. 3. Both fans are activated in parallel from start to full load. 4. If the fans 6 and 7 have very different operating points, the fan with the lower operating point can be activated first for low outputs, then in a specific partial load range the other fan with the higher operating point takes over, whereby in a higher output range both fans 6 and 7 are activated up to full load.

[0021] The present invention makes it possible to reduce the consumption of electrical energy in a fuel-operated heating appliance 1 and to carry out efficient, robust operation with high availability in a wide modulation range of the blower power. Reference symbol list

[0022] 1 Heater 2 Air inlet 3 Fuel inlet 4 Control unit 5 Fuel valve 6 First blower 7 Second blower 8 Burner 9 Combustion chamber 10 Exhaust system 11 Control lines

Claims

1. Arrangement consisting of a heating device for operating the heating device (1), in which hydrogen or a hydrogen-containing fuel gas is mixed with an air flow as fuel, the resulting mixture is burned in a combustion chamber (9) and the resulting combustion gases are discharged via an exhaust system (10), wherein the heating device (1) has a first fan (6) and a second fan (7) connected in series thereto, which are connected to a control and regulation unit (4) via separate control lines (11) and can be controlled individually; wherein the control and regulation unit (4) is designed to distribute the fan power required for a predeterminable output of the heating device (1) to the first fan (6) and the second fan (7) in such a way that the lowest possible power consumption is achieved, characterised in that at least one of the fans (6, 7) has a maximum fan power that is lower than the total fan power required for maximum output of the heating device (1).

2. Arrangement according to claim 1, wherein the first fan (6) and the second fan (7) are arranged upstream of the combustion chamber (9).

3. Arrangement according to claim 1, wherein the second fan (7) is arranged downstream of the combustion chamber (9) in the exhaust system (10).

4. Arrangement according to one of the preceding claims, wherein both fans (6, 7) have different design points at which they each have the lowest energy consumption per fan power.

5. Method for operating the heating device (1) in which hydrogen or a hydrogen-containing fuel gas is mixed with an air flow as fuel, using the arrangement according to one of claims 1 to 4, wherein only one or both blowers (6, 7) are operated depending on the currently required output of the heating device (1).

6. Method according to claim 5, wherein, when only one fan (6, 7) is in operation, the one is selected whose design point is closest to a required fan output for the currently required output of the heating device (1).

7. Method according to one of claims 5 and 6, wherein calibration data is stored in a provided control and regulation unit (4), which data specifies the optimum distribution to the first fan (6) and the second fan (7) for each total fan output.

8. Method according to one of claims 5 to 7, wherein the current power consumption of both fans (6, 7) is supplied to the control and regulation unit (4) and the control and regulation unit (4) determines and sets a minimum of the current power consumption by changing the distribution of the power between both fans (6, 7).

9. Computer program product comprising instructions that cause the arrangement according to one of claims 1 to 4 to execute the method according to one of claims 5 to 8.