EP4108988A1

EP4108988A1 - Method and mechanism for controlling the operation of a boiler

Info

Publication number: EP4108988A1
Application number: EP21181520.4A
Authority: EP
Inventors: Sebastiano Temperato; Andrea Pisoni; Job Rutgers
Original assignee: BDR Thermea Group BV
Current assignee: BDR Thermea Group BV
Priority date: 2021-06-24
Filing date: 2021-06-24
Publication date: 2022-12-28
Also published as: WO2022269017A1; EP4359703A1

Abstract

The invention relates to a method for controlling the operation of a boiler (1) having a fuel supply system (2) for supplying fuel gas, in particular hydrogen, from a fuel supply (3) to a fuel gas combusting burner (4), the method comprising determining (S101) whether a risk situation exists based on a security criterion, blocking (S102) the supply of fuel gas in the fuel supply system (2) by means of a first gas valve (5) in case the security criterion is not satisfied, and providing (S103) the burner (4) with fuel gas from the fuel supply (3) by operating at least a second gas valve (6) of the fuel supply system (2) in presence of a heat request, in case the security criterion is satisfied, wherein the security criterion is based on a safety parameter associated with a concentration of fuel gas, in particular of hydrogen, in the fuel supply system (2) and/or on a detected electrical fault in the fuel supply system (2).

Description

The invention relates to a method for controlling the operation of a boiler. Additionally, the invention relates to a safety mechanism and to a gas boiler comprising said mechanism and to a use of the safety mechanism for controlling the operation of a gas boiler or in a heating system. In addition, the invention relates to a computer program product.
Gas boilers combust gas fuel to heat water for domestic use and/or central heating systems in buildings. Exhaust flue gas is generated by this combustion. Usually, a central heating water circuit is heated, as well as a hot water supply. A gas leak, both considering the combustible fuel gas or the exhaust flue gas, can be very dangerous. In fact, the gas can accumulate in closed spaces, such as the room containing the boiler or even the boiler's cabinet, and determine the conditions for an explosion. Several operating components of the gas boiler, such as the fan or the pump can indeed trigger for an explosion. It is therefore desirable to promptly avoid risky situations thereby preventing an explosion. It is particularly desirable to avoid that the operating parts of the boiler can trigger an explosion in case of gas leak. It is furthermore desirable to maintain the safety of the boiler system even in case of malfunctioning of internal safety devices.
US 2008/0223946 A1 is directed to gas controlling and blocking valves to be used in an automatic warm water circulator. To automatically control the quantity of gas or to block the gas, the gas control valve and a gas blocking valve comprise valve pistons automatically moving up and down due to an elastic force and vapor pressure. In this way, the automatic warm water circulator is configured to adjust the temperature of a boiler using the gas control valve and the above gas blocking valve, for continuously producing and supplying warm water by taking advantage of the vapor pressure change occurring when water in the boiler is transformed into vapor. Accordingly, the valves are automatically opened and closed according to vapor pressure change without a separate power source.
US 9,151,490 A1 is directed to a boiler control system for efficiently controlling the operation of a packaged boiler. The system includes a combustion air control system, a fuel control system, a flue gas sensing system, and a boiler controller. The boiler controller is in operative communication with the combustion air control system, fuel control system, and the flue gas sensing system. Based upon a system demand, the boiler controller controls coarse-level operation of the combustion air control system and the fuel control system. The flue gas sensing system includes an oxygen sensor and a flue gas differential sensor to sense a change in a characteristic of the flue gas. When the flue gas differential sensor senses a change in the flue gas characteristic that meets a flue gas differential set point, the boiler controller controls the fine-level operation of the boiler.
US 9,816,891 B2 is directed to a gas leakage checking device and a corresponding method for checking fuel-gas leakage of safety shutoff valves by measuring a pressure in a fuel supply pipe. The gas-leakage checking device includes a first safety shutoff valve disposed in a fuel-gas supply pipe of the gas internal combustion engine for permitting or shutting off a flow of the fuel gas, a second safety shutoff valve disposed on a downstream side of the first safety shutoff valve, a gas-leakage checking pipe branched from between the first and second safety shutoff valves, a gas-discharge valve disposed in the gas-leakage checking pipe and configured to discharge the fuel gas between the first and second safety shutoff valves, a first pressure meter for detecting a pressure of the fuel gas in the gas-leakage checking pipe, and second pressure meters disposed on a downstream side of the second safety shutoff valve, for detecting the pressure of the fuel gas in the fuel-gas supply pipe.
EP 2 952 792 A1 is directed to an electronic gas safety control means comprising an electronic shut-off valve, which is normally closed, and is opened to supply gas from a gas source to a gas appliance for heating purposes; and a controller electrically connected to the electronic shut-off valve and having at least a sensor for sensing dangerous leaking gas, carbon monoxide, smoke or earthquake and also for issuing a close signal to close the electronic shut-off valve for enhancing the gas safety.
The documents that are discussed above disclose devices, systems and methods that are complicate to implement. Also, these are not suitable to maintain the safety conditions even in case of gas leakage already occurred and/or in case of failure of dedicated safety control mechanisms.
The object of the invention is therefore to provide a method for controlling the operating of a boiler that is easy to implement and by means of which a dangerous situation, in particular a dangerous situation for human health, can be prevented.
The object is solved by a method for controlling the operation of a boiler having a fuel supply system for supplying fuel gas, in particular hydrogen, from a fuel supply to a fuel gas combusting burner, the method comprising:

determining whether a risk situation exists based on a security criterion;
blocking the supply of fuel gas in the fuel supply system by means of a first gas valve in case the security criterion is not satisfied; and
providing the burner with fuel gas from the fuel supply by operating at least a second gas valve of the fuel supply system in presence of a heat request, in case the security criterion is satisfied,
wherein the security criterion is based on a safety parameter associated with a concentration of fuel gas, in particular of hydrogen, in the fuel supply system and/or on a safety parameter associated with a detected electrical fault in the boiler.

As an advantage, the method increases the safety of the boiler due to the operation on two separate gas valves used to prevent the fuel gas to be supplied to the burner if a particular security criterion is not fulfilled. It is noted that the security criterion is not only related to the concentration of the fuel gas in the boiler caused for example by a gas leakage but also to a possible electrical fault in the boiler. With electrical fault is intended for example that a leakage sensor is not correctly operating and/or another safety device (i.e. an internal gas valve such as the second gas valve) is not functioning. It is noted that the first gas valve can be directly connected to the fuel supply. Therefore, the first gas valve can be actuated to promptly block the gas supply in the fuel supply system and thereby avoiding a possible explosion in the boiler. For example, when associated with the concentration of fuel gas, the safety parameter can be a threshold concentration value of said fuel gas so that if the concentration value exceeds the threshold value, a risky situation exists. On the other hand, when associated with a detected electrical fault in the boiler, the safety parameter can be for example a threshold current/voltage value so that when the measured current/voltage is above or below said threshold, a risky situation exists. It is noted that in this case the safety parameter can represent a set of safety parameters within a certain security range.
A dangerous situation is a situation in which a danger for human health exists. This situation can result from that a leaked gas has reached an explosive level. An unwanted explosion can then be triggered by the operating components of the boiler. Additionally, a dangerous situation exists if the leaked gas is toxic or is asphyxiating.
In one example, to improve the safety, the first gas valve is always in the close position and the method comprises opening the first gas valve only when both the security criterion is satisfied and the heat request is present. Accordingly, even during the standby phase of the boiler, i.e. when the heat request is not yet present, the first gas valve is close.
In another example, the method comprises displaying a dedicated error associated with the risk situation in case the security criterion is not satisfied. In this way, it is possible to immediately identify the risk situation and also the type of error/problem, i.e. gas leakage or sensor/second gas valve defect. Advantageously, a sound effect can be associated to the displayed error.
In examples, the method comprises shutting down the boiler in case the security criterion is not satisfied. Also, the method can comprise entering a standby mode in the absence of a heat request. In addition, the method comprises providing the burner with fuel gas until the heat request is satisfied. These are expedients to increase the general safety of the system.
In one example, providing the burner with fuel gas from the fuel supply involves adjusting a flow of fuel gas with respect to the heat request by operating the at least the second gas valve of the fuel supply system. In other words, once the security criterion is satisfied, the second gas valve can be used to regulate the gas flow to be supplied to the burner in accordance with the heat request. It is noted that the second gas valve can also be configured to completely block the supplying of the fuel gas to the burner. Therefore, the second gas valve can be used as an additional safety device together with the first gas valve in order to eventually isolate the fuel gas (if any) in a region defined between the first gas valve and the second gas valve.
In examples, the security criterion involves a threshold condition on the concentration of the fuel gas, in particular of hydrogen, in the fuel supply system. In other words, if the gas concentration exceeds a predetermined threshold value, the security criterion is not satisfied and the supply of the fuel gas to the fuel supply system is blocked by the first gas valve. For example, said threshold value can be comprised between 0.3% and 0.4% of gas concentration in the fuel supply system, in particular, in a cabinet of the boiler.
A further object of the invention is to provide a safety mechanism that is easy to implement and by means of which a dangerous situation, in particular a dangerous situation for human health, can be prevented.
The object is solved by the mechanism for controlling the operation of a boiler, in particular of a boiler for domestic hot water generation or central heating, the mechanism comprising:

a first gas valve and at least a second gas valve, located downstream the first gas valve, the first gas valve and the second gas valve being included in a fuel supply system of the boiler that is configured to provide a burner of the boiler with fuel gas from a fuel supply, wherein the boiler is contained in a cabinet and the first gas valve is located outside the cabinet and the second gas valve is located inside the cabinet;
a leakage sensor for determining a concentration of fuel gas, in particular hydrogen, in the fuel supply system; and
a control unit connected to the first gas valve, the second gas valve and the leakage sensor configured to determine whether a risk situation exists based on a security criterion, to block the supply of fuel gas in the fuel supply system by means of the first gas valve in case the security criterion is not satisfied and to operate the at least second gas valve of the fuel supply system in presence of a heat request, thereby providing the burner with fuel gas from the fuel supply, in case the security criterion is satisfied,
wherein the security criterion is based on a safety parameter associated with a concentration of fuel gas, in particular of hydrogen, in the fuel supply system and/or on a safety parameter associated with a detected electrical fault in the boiler.

Differently from the prior art systems, the control unit is not only connected to the leakage sensor but also is directly connected to the first gas valve in order to promptly block the fuel gas supply based on the gas concentration measured by the leakage sensor and/or based on an electrical fault of the boiler, for example of the sensor itself.
In one example, the first gas valve can be a shut-off valve configured to at least block and release the supply of fuel gas in the fuel supply system. Also, the at least second gas valve can be a control valve configured to adjust the flow of fuel gas with respect to the heat request. In addition, the leakage sensor is configured to measure a concentration of fuel gas, in particular hydrogen, in the fuel supply system.
In examples, the control unit can comprise a printed circuit board that is connected to the first gas valve through a terminal block or electric plug. For example, the output in the printed circuit board can be a contact in a terminal block and provides power supply. The output can directly connected to a 120V or 230V (Voltage) gas valve (i.e. first gas valve). The action to open or close the first gas valve can be driven by the software applied in the control unit (for example microcontroller or processor) on the printed circuit board.
According to an aspect of the invention, a gas boiler, in particular a hydrogen boiler, comprising the inventive safety mechanism and/or configured for carrying out the inventive method is provided.
According to an additional aspect of the invention, a use of a safety mechanism as described above for controlling the operation of a gas boiler, in particular of a boiler for domestic hot water generation or central heating is provided.
Additionally, an advantageous embodiment is a computer program product comprising instructions which, when the program is executed by a control unit, cause the control unit to perform the inventive method. Furthermore, a data carrier is provided on which the computer program is stored and/or data carrier signal is provided which transmits the computer program. A building management system can comprise a control unit in order to execute the aforementioned program. Additionally or alternatively a fire alarm system of a building and/or apartment can comprise a control unit in order to execute the aforementioned program.
In the figures, the subject-matter of the invention is schematically shown, wherein identical or similarly acting elements are usually provided with the same reference signs.

Figure 1: shows a flow chart of the method according to an example.
Figure 2: shows a detailed flow chart of the method according to an example.
Figure 3A: shows a schematic representation of a safety mechanism according to an example.

Figure 3B: shows a schematic representation of a heating system according to an example.
Figure 4: shows a detailed representation of a heating system according to an example.

Figure 1

method

boiler

fuel supply system

first gas valve

boiler

first gas valve

boiler

burner

fuel supply

second gas valve

fuel supply system

second gas valve

first gas valve

boiler

The method 200 for controlling the operation of a boiler 1 is illustrated in more detail in Figure 2. The method 200 starts turning on the main power of the system (S201). Accordingly, the boiler 1 is turned on (S202). It is noted that at step S202 the first gas valve 5 can be in a close configuration. At step S203, it is determined whether a risk situation exists based on a security criterion. The security criterion comprises two conditions. In a first condition (S204), the level of fuel gas, i.e. Hydrogen, is measured. If the level of fuel gas is determined to be lower than a predefined threshold value (e.g. 0.4%), the first condition is satisfied. If, on the other hand, the fuel gas level is higher that the predefined threshold value, the first condition is not satisfied and a risk situation occurs. In a second condition (S205), electrical anomalies are checked by the control unit 9. In particular, faulty sensor or issues on the electrical connection are checked, for example by measuring the current or the voltage associated to a device inside the boiler (leakage sensor or second gas valve). If no electrical anomalies are found, the second condition is satisfied. If, on the other hand, at least one electrical anomaly is detected, the second condition is not satisfied and a risk situation occurs. Based on the combination of these two conditions, the method can determine whether a risk situation exists or does not exist. In this case, safety parameters are taken into account, such as a threshold concentration value of the fuel gas and/or a measured current or voltage value.
In case a risk situation exists, that is either the first condition or the second condition is not satisfied, the first gas valve 5 is checked to be sure that it is close (S206). Should the first gas valve 5 not be close, this valve 5 is immediately closed. Accordingly, a dedicated alarm message is generated (S207) and the boiler 1 is in lockout (S208).
In case both the first and second condition are satisfied, no risk situation exists and a heating request is checked at step S209. If no heating request is present, the boiler 1 is set in standby mode (S210), and the method 200 goes back to step S203 for checking new possible risky situations during the standby. On the other hand, if a heating request is present the ignition is started (S211) and the boiler 1 is set in the operation mode (S212). It is noted that after completing the operation mode, the method can return to step S203 for monitoring the presence of a risky situation.
Figures 3A and 3B illustrate schematic representations of a safety mechanism 7 and a heating system 16 according to examples of the disclosure. The safety mechanism 7 basically comprises a first gas valve 5, a second gas valve 6 and a leakage sensor 8. Also, the mechanism 7 comprises a control unit 9 connected to the first gas valve 5, the second gas valve 6 and the sensor 8. Thanks to a dedicated output on a printed circuit board of the control unit 9, the first gas valve 5 can be controlled and activated to prevent the fuel gas from being supplied to the burner 4 of the boiler 1. This is schematically represented in figure 3B.
The two gas valves are included in a fuel supply system 2 that fluidically connects a fuel supply 3 (e.g. a gas storage element or a gas supply pipe) to the burner 4 of a boiler 1. The first gas valve 5 is located outside the boiler 1, whereas the second gas valve 6 is located inside the boiler 1 and downstream the first gas valve 5. The control unit 9 can directly act on the fuel supply system 2, and therefore on the first gas valve 5 and second gas valve 6 in order to block the fuel gas supply to the burner 4, if a risk situation is determined, that is if the security criterion is not satisfied. It is noted that the control unit 9 can advantageously be connected to the burner 4 in order to check and regulate other devices connected to the burner, such as temperature sensors.
Figure 4 shows a heating system 16 in more detail according to an example of the disclosure. The heating system 16 comprises a gas boiler 1, in particular a hydrogen boiler. The boiler 1 comprises several operating components that are located inside a cabinet 10. The components comprise at least a fan 13, a burner 4 and a heat exchanger 14. The functioning of these components 4, 13, 14 is controlled by the control unit 9 that is for example also located in the cabinet 10. It is noted that the control unit 9 also controls the functioning of other elements, such as the opening or closing of gas valves 5, 6. The hydrogen gas enters the boiler's cabinet 10 through a gas conduit 11 from a fuel supply 3. A first gas valve 5, located outside the cabinet 10, can be opened or closed by the control unit 9 to regulate the gas inlet, for example if a risk situation is determined. The second gas valve 6, located downstream the first gas valve 5 and inside the cabinet 10, is placed at the entrance of the burner 4 to regulate the flow of fuel gas with respect to the heat request. The second gas valve 6 can also be closed to completely prevent the fuel gas from entering into the burner 4. Prior to combustion, the hydrogen can be mixed with air introduced in the cabinet 10 through an air conduit 12. In particular, hydrogen and air are forced or blown into the boiler 1 using the fan 13. The gas mixture is ignited by an ignition system in the burner 4. The combustion of the gas mixture results in hot flue gas which flows through the heat exchanger 14 transferring heat to the water system. The flue gas is for example ducted to the top of the cabinet 10 and exits the cabinet 10 through an exhaust conduit 15.
The control unit 9 is also connected to a leakage sensor 8 located inside the cabinet 10 for measuring the level of gas concentration in the cabinet 10.
The presence of two gas valves 5, 6 connected to the control unit 9 increases the safety of the system, In particular, placing the first gas valve 5 outside the cabinet 10 of the boiler 1 allows the system 16 to prevent the fuel gas from entering into the cabinet 10 of the boiler in case risky situations are determined, thereby avoiding possible explosions triggered by internal components of the boiler 1. Furthermore, the possibility to simultaneously controlling the first gas valve 5 and the leakage sensor 8 by the control unit 9, ensures that the first gas valve 5 can be closed not only in case of gas leakage but also in case of an electrical fault detected in the system 16, such as for example defect in the sensor 8 or electrical issues in the connections to the first gas valve 5 and/or the second gas valve 6.

Reference Signs

1.: Boiler
2: Fuel supply system
3: Fuel supply
4: Burner
5: First gas valve
6: Second gas valve
7: Safety mechanism
8: Leakage sensor
9: Control unit
10: Cabinet
11: Gas conduit
12: Air conduit
13: Fan
14: Heat exchanger
15: Exhaustion gas conduit
16: Heating system
17: Terminal block
100: Method
200: Method

Claims

Method for controlling the operation of a boiler (1) having a fuel supply system (2) for supplying fuel gas, in particular hydrogen, from a fuel supply (3) to a fuel gas combusting burner (4), the method comprising:
determining (S101) whether a risk situation exists based on a security criterion;

blocking (S102) the supply of fuel gas in the fuel supply system (2) by means of a first gas valve (5) in case the security criterion is not satisfied; and

providing (S103) the burner (4) with fuel gas from the fuel supply (3) by operating at least a second gas valve (6) of the fuel supply system (2) in presence of a heat request, in case the security criterion is satisfied,

wherein the security criterion is based on a safety parameter associated with a concentration of fuel gas, in particular of hydrogen, in the fuel supply system (2) and/or on a safety parameter associated with a detected electrical fault in the boiler (1).
Method (100) according to claim 1, characterized by opening the first gas valve (5) only when both the security criterion is satisfied and the heat request is present.
Method (100) according to claim 1 or 2, characterized by displaying a dedicated error associated with the risk situation in case the security criterion is not satisfied.
Method (100) according to any one of the claims 1 to 3, characterized by shutting down the boiler (1) in case the security criterion is not satisfied.
Method (100) according to any one of the claims 1 to 4, characterized by entering a standby mode in the absence of a heat request.
Method (100) according to any one of the claims 1 to 5, characterized in that providing the burner (1) with fuel gas from the fuel supply (3) involves adjusting a flow of fuel gas with respect to the heat request by operating the at least the second gas valve (6) of the fuel supply system (2).
Method (100) according to any one of the claims 1 to 6, characterized by providing the burner (1) with fuel gas until the heat request is satisfied.
Method (100) according to any one of the claims 1 to 7, characterized in that the security criterion involves a threshold condition on the concentration of the fuel gas, in particular of hydrogen, in the fuel supply system (2).
Safety mechanism (7) for controlling the operation of a boiler (1), in particular of a boiler for domestic hot water generation or central heating, the mechanism comprising:
a first gas valve (5) and at least a second gas valve (6), located downstream the first gas valve (5), the first gas valve (5) and the second gas valve (6) being included in a fuel supply system (2) of the boiler (1) that is configured to provide a burner (4) of the boiler (1) with fuel gas from a fuel supply (3), wherein the boiler (1) is contained in a cabinet (10) and the first gas valve (5) is located outside the cabinet (10) and the second gas valve (6) is located inside the cabinet (10);

a leakage sensor (8) for determining a concentration of fuel gas, in particular hydrogen, in the fuel supply system (2); and

a control unit (9) connected to the first gas valve (5), the second gas valve (6) and the leakage sensor (8) configured to determine whether a risk situation exists based on a security criterion, to block the supply of fuel gas in the fuel supply system (2) by means of the first gas valve (5) in case the security criterion is not satisfied and to operate the at least second gas valve (6) of the fuel supply system (2) in presence of a heat request, thereby providing the burner (4) with fuel gas from the fuel supply (3), in case the security criterion is satisfied,

wherein the security criterion is based on a safety parameter associated with a concentration of fuel gas, in particular of hydrogen, in the fuel supply system (2) and/or on a safety parameter associated with a detected electrical fault in the boiler (1).
Mechanism (7) according to claim 9, characterized in that
a. the first gas valve (5) is a shut-off valve configured to at least block and release the supply of fuel gas in the fuel supply system (2); and/or

b. the at least second gas valve (6) is a control valve configured to adjust the flow of fuel gas with respect to the heat request.
Mechanism (7) according to claim 9 or 10, characterized in that the leakage sensor (8) is configured to measure a concentration of fuel gas, in particular hydrogen, in the fuel supply system (2).
Mechanism (7) according to any one of the claims 9 to 11, characterized in that the control unit (9) comprises a printed circuit board that is connected to the first gas valve (5) through a terminal block (17).
Gas boiler (1), in particular a hydrogen boiler, comprising the safety mechanism (7) of one of the claims 9 to 12 and/or configured for carrying out the method (100) of one of the claims 1 to 8.
Use of a safety mechanism (7) according to any one of the claims 9 to 12 for controlling the operation of a boiler (1), in particular of a boiler for domestic hot water generation or central heating.
Computer program product comprising instructions which, when the program is executed by a computer or control unit, cause the computer or the control unit to carry out the method (100) according to one of the claims 1 to 8.