Patent Application
20250172287
The present disclosure relates to controllers for boiler and furnace systems, in particular, controllers for controlling the blend of gas and air provided to the combustion chamber of the boiler.
Boilers and furnaces are used for various processes and heating applications, including water heating, central heating, boiler-based power generation, cooking, and sanitation. The boiler includes a combustion chamber. A fuel source is released into the combustion chamber, along with air, and combusts to create heat energy. Conventional fuel sources include, but are not limited to, coal, oil, and natural gas.
Recently, other non-carbon-based fuels, such as hydrogen (H2), have been used in boiler applications to improve sustainability. For example, the European Union has considered banning pure natural gas (CH4) boilers beginning in 2029. As a result, boiler and furnace manufacturers are beginning to develop boilers and furnaces that blend non-carbon fuels with traditional fuels, such as H2+CH4. To achieve efficient combustion, the amount of air provided must be controlled in relation to the type of gas blend.
Aspects provide systems and methods for controlling an air flow rate provided to a burner based on the concentration of one or more gases provided to the burner. The method for controlling a burner including receiving a gas concentration value indicating a concentration of one or more gases in a gas mixture provided to a burner; determining, using the gas concentration value, an air flow rate to input to the burner; and controlling the air flow rate provided to the burner based on the determined air flow rate.
An apparatus includes a control circuit to receive a gas concentration value indicating a concentration of one or more gases in a gas mixture provided to a burner; determine, using the gas concentration value, an air flow rate to input to the burner; and control the air flow rate provided to the burner based on the determined air flow rate.
A system includes a gas concentration sensor, a ventilator, and a control circuit. The control circuit to receive a gas concentration value, from the gas concentration sensor, indicating a concentration of one or more gases in a gas mixture provided to a burner; determine, using the gas concentration value, an air flow rate to input to the burner; and control the air flow rate provided to the burner based on the determined air flow rate.
Example aspects of the present disclosure are described below in conjunction with the figures, in which:
The reference number for any illustrated element that appears in multiple different figures has the same meaning across the multiple figures, and the mention or discussion herein of any illustrated element in the context of any particular figure also applies to each other figure, if any, in which that same illustrated element is shown.
According to an aspect of the invention, a controller measures the percentage of one or more gases in a fuel source provided to a burner, such as boilers, water heaters, hot air generators, and/or wall hung boilers, used for residential, commercial, industrial, and/or transportation applications. Based on the measurement, the controller calculates the amount of air to be provided to the combustion chamber to achieve perfect or near-perfect combustion. In this way, the controller avoids losses into the ambient environment and provides cost savings due to the improved combustion efficiency.
System 100 receives a gas mixture. The gas mixture may be a blend of one or more gases. The gas mixture is input to concentration sensor circuitry 110. Concentration sensor circuitry 110 may measure, and or determine, the concentration of respective gases in the gas mixture. For example, the gas mixture may be a blend of hydrogen (H2) and natural gas (CH4). Concentration sensor circuitry 110 may measure the concentration of H2 and determine the concentration of CH4, such as 20% H2 and 80% CH4. The concentration of each gas in the gas mixture may vary based on several factors including, but not limited to, the supplier of the gas mixture, the distance from the source of the gas mixture, and the current demand for the gas mixture from other users between the source and system 100. Concentration sensor circuitry 110 may be implemented in any suitable combination of analog and digital circuitry, such as a suitable microprocessor, microcontroller, control board, or other computing device having input and output interfaces for communicating with other devices, as well as memory or other storage for program logic/instructions that concentration sensor circuitry 110 executes to send and receive signals and process data. There is no requirement that the concentration of the respective gases be each separately measured. For example, if there is a mixture of H2 and CH4, measuring the concentration of H2 is sufficient to determine the concentration of CH4.
Concentration sensor circuitry 110 outputs a signal to controller 120 indicating the concentration of each gas in the gas mixture. The signal may be in the form of program instructions, digitalized information signal, or any other suitable digital or analog signal. Controller 120 may control the operation of one or more components of system 100, for example safety gas valve 130 and/or ventilator 140 (e.g., a fan). Controller 120 may be implemented in any suitable combination of analog and digital circuitry, such as a suitable microprocessor, microcontroller, control board, or other computing device having input and output interfaces for communicating with other devices, as well as memory or other storage for program logic/instructions that controller 120 executes to send and receive signals and process data. By measuring, and/or determining, the concentration of the different gases in the gas mixture, system 100 may be controlled more efficiently than using traditional post-burning feedback because by measuring and/or determining the amount of each gas at the input of burner 150, a control loop, such as controller 120 can calculate the amount of air needed to improve combustion.
In some examples, controller 120 manages safety gas valve 130 and/or ventilator 140 by transmitting instructions, or commands, that safety gas valve 130 and/or ventilator 140 execute. Additionally, or alternatively, controller 120 may control safety gas valve 130 and/or ventilator 140 by pulse-width modulation (PWM), which may be in the form of a PWM signal, through an on/off enabler to provide a voltage to safety gas valve 130 and the use of PWM to modulate the provided voltage, or through direct PWM of the current provided to safety gas valve 130 and/or ventilator 140.
Safety gas valve 130 may prohibit the flow of the gas mixture into burner 150 if an unsafe condition occurs. Safety gas valve 130 may be actuated by a control signal from controller 120 and operate according to the control signal parameters. For example, if controller 120 identifies an unsafe condition, such as the absence of a flame in burner 150, controller 120 outputs a signal to safety gas valve 130 to close safety gas valve 130. As described previously, the signal output from controller 120 to safety gas valve 130 may be a PWM signal, program instructions, and/or a general-purpose input/output (GPIO) signal. Safety gas valve 130 may also modulate the amount of gas provided to burner 150.
Ventilator 140 may be used to control the amount of air combined with the gas mixture at mixer 160 before the gas/air mixture enters burner 150. Ventilator 140 may control the air flow rate provided to mixer 160 based on the rotation speed of ventilator 140. The rotation speed may be determined by the pulse width or period of a PWM signal: a shorter pulse width may cause ventilator 140 to rotate slower. Correspondingly, the power consumption of ventilator 140 changes according to the control signal. For example, a shorter pulse that causes ventilator 140 to spin slower also causes ventilator to use less current during operation. Controller 120 may apply the control signal to ventilator 140 continuously, at predetermined intervals, or only when controller 120 changes a parameter of the control signal.
Controller 120 may process one or more inputs to determine the parameters of the control signal. One or more inputs may be provided by concentration sensor circuitry 110. For example, controller 120 may obtain the present (i.e., real-time) gas mixture concentration or a rate or other value describing the concentration of the gas mixture. Controller 120 may use the gas mixture concentration to determine the air (e.g., oxygen) flow rate to combine with the gas mixture to achieve efficient combustion. The air flow rate is varied by controller 120 based on the type and concentration of gases in the gas mixture. For example, natural gas may require a higher amount of air than propane to achieve near perfect combustion while hydrogen requires a higher amount of air than natural gas. Controller 120 is provided with information regarding the respective gases being provided so as to properly determine the appropriate air flow rate.
Controller 120 may additionally, or alternatively, receive as inputs data describing the real-time or past operation of burner 150. One such input may include a flame signal reading value produced by flame signal reading circuitry 170. Controller 120 may update the control signal to close safety gas valve 130 (i.e., to inhibit the flow of gas towards burner 150) if the flame signal indicates that the main flame in burner 150 is not lit. Alternatively, controller 120 may update the control signal to maintain safety gas valve 130 in an open position (i.e., to allow the flow of gas towards burner 150) if the flame signal indicates that the main flame in burner 150 is lit. By using input from flame signal reading circuitry 170, controller 120 may be safety certified, such as IEC60730 EN298 Class C certified.
Flame signal reading circuitry 170 receives a flame signal from flame sensor 175 in burner 150. The flame signal may be in the form of a voltage, current, digital signal, or any other analog or digital signal format that communicates the presence of a flame in burner 150. Flame signal reading circuitry 170 may be implemented in any suitable combination of analog and digital circuitry, such as a suitable microprocessor, microcontroller, control board, or other computing device having input and output interfaces for communicating with other devices, as well as memory or other storage for program logic/instructions that flame signal reading circuitry 170 executes to send and receive signals and process data. Flame signal reading circuitry 170 outputs a signal to controller 120 to indicate whether a flame is present in burner 150. The signal may be in the form of program instructions, digitalized information signal, or any other suitable digital or analog signal. In some examples, flame sensor 175 may be coupled to controller 120 without the use of flame signal reading circuitry 170.
Controller 200 may include concentration sensor interface 210 to receive a signal from a concentration sensor circuitry, such as concentration sensor circuitry 110 shown in
Controller 200 may also include thermostat interface 220 for sending and receiving signals to and from a thermostat. Thermostat interface 220 may be any suitable type of interface, such as an I2C bus, SPI, and/or UART interface. A user may use the thermostat to set a temperature at which a burner, such as burner 150 shown in
Controller 200 may further include flame signal interface 230 to receive a signal from a flame signal reading circuitry, such as flame signal reading circuitry 170 shown in
Controller 200 may include air machine interface 240 to send a signal to a ventilator, such as ventilator 140 shown in
Controller 200 may additionally include safety valve interface 250 to send a signal to a valve, such as safety gas valve 130 shown in
Controller 200 further includes control algorithm 260 to receive inputs, perform algorithmic processing, and produce outputs. These inputs and outputs may be communicated using, for example, concentration sensor interface 210, thermostat interface 220, flame signal interface 230, air machine interface 240, or safety valve interface 250. Control algorithm 260 may be implemented using any combination of program instructions and circuit components that provide the described functionality.
Control algorithm 260 may include a control loop that is implemented using either a proportional-integrative-derivative (PID) controller or a proportional-integrative (PI) controller. A PI controller may be used in implementations where the concentration of the gas mixture is stable, while a PID controller may be used in implementations where the concentration of the gas mixture varies across time. In implementations where control algorithm 260 includes a PID controller, the PID controller may include a proportional gain Kp, an integrative gain Ki, and a derivative gain Kd. In implementations where control algorithm 260 includes a PI controller, the PI controller may include a proportional gain Kp and an integrative gain Ki. The gains may have gas mixture concentration as an input and a setpoint for a speed that corresponds to an air flow rate as an output. The integrative gain Ki may further pass its output through an integrative accumulator. The derivative gain Kd may further pass its output through a derivative accumulator. These accumulators may refine the setpoint according to a trend of recent historical recorded values of the gas mixture concentration.
In some examples, control algorithm 260 may include a lookup table. When control algorithm 260 receives a given concentration of a gas from concentration sensor interface (e.g., the concentration of H2 in the gas), control algorithm 260 may look up the amount of air to provide to the burner for the given concentration of gas. The lookup table of control algorithm may be based on the amount of air to add to a given gas concentration to achieve efficient combustion. The lookup table may be specific to the boiler. For example, the amount of air to add to a given gas concentration may depend on the mechanics (e.g., shape and size) of the burner.
Boiler system 300 may include one or more gas valves 305a-305d into which one or more gases are provided. Gas valves 305a-305d may control the amount of gas permitted to flow into system 300. For example, gas valve 305a may control the amount of gas 1 permitted to flow into system 300, gas valve 305b may control the amount of gas 2 permitted to flow into system 300, and so forth. Gas valves 305a-305d may be coupled to mixer 380 where the gases 1 through n are combined to become a gas mixture. Gas valves 305a-305d and mixer 380 may be at the gas supplier's premises and the gas mixture may be provided to customers after mixing.
The gas mixture flows into concentration sensor circuitry 310, which may be similar to concentration sensor circuitry 110 shown in
In some examples, controller 320 manages safety gas valve 330 and/or ventilator 340 by transmitting program instructions that safety gas valve 330 and/or ventilator 340 execute. Additionally, or alternatively, controller 120 may control safety gas valve 330 and/or ventilator 340 by pulse-width modulation (PWM), which may be in the form of a PWM signal or through direct PWM of the current provided to safety gas valve 330 and/or ventilator 340.
Safety gas valve 330 may be used to prohibit the flow of the gas mixture into burner 350 if an unsafe condition occurs. Safety gas valve 330 may be similar to safety gas valve 130 shown in
Ventilator 340 may be used to control the amount of air added to burner 350. Ventilator 340 may control the air flow rate provided to burner 350 based on the rotation speed of ventilator 340. The rotation speed may be determined by the pulse width or period of a PWM signal: a shorter pulse width may cause ventilator 340 to rotate slower. Correspondingly, the power consumption of ventilator 340 changes according to the control signal. Ventilator 340 may be similar to ventilator 140 shown in
Controller 320 may process one or more inputs to determine the parameters of the control signal. One or more inputs may be provided by concentration sensor circuitry 310. For example, controller 320 may obtain the present (i.e., real-time) gas mixture concentration or a rate or other value describing the concentration of the gas mixture. Controller 120 may use the gas mixture concentration to determine the air flow rate to combine with the gas mixture to achieve efficient combustion. The air flow rate required varies based on the type and concentration of gases in the gas mixture. In some examples, the type of gases in the gas mixture may be provided by the supplier of the gas mixture (e.g., a utility provider).
Controller 320 may additionally or alternatively receive, as inputs, data describing the real-time or past operation of burner 350. One such input may include the exhaust gas concentration from exhaust gas concentration sensor 385. For example, exhaust gas concentration sensor 385 may measure the amount of oxygen or nitrogen oxide in the exhaust from burner 350 to monitor the efficiency of the combustion in burner 350. As another example, exhaust gas concentration sensor 385 may measure the amount of water vapor (H2O) in the exhaust from burner 350 to determine the amount of H2 originally provided to burner 350. Controller 320 may use the exhaust gas concentration as an input into its control logic, such as control algorithm 460 shown in
Another input to controller 320 may include the temperature from temperature sensor 390. For example, temperature sensor 390 may measure the ambient air temperature. Controller 320 may use the temperature information to determine whether the temperature is equal to the desired temperature, such as the temperature set on a thermostat. If the temperature is lower than the desired temperature, controller 320 may send a signal to light burner 350.
Additionally, controller 400 may include exhaust gas concentration sensor interface 470 to receive a signal from an exhaust gas concentration sensor, such as exhaust gas concentration sensor 385 shown in
Controller 400 may include ambient air temperature interface 480 for receiving a signal from a temperature sensor, such as temperature sensor 390 shown in
Controller 400 further includes control algorithm 460 to receive inputs, perform algorithmic processing, and produce outputs. These inputs and outputs may be communicated using, for example, concentration sensor interface 410, thermostat interface 420, flame signal interface 430, air machine interface 440, safety valve interface 450, exhaust gas concentration sensor interface 470, or ambient air temperature interface 480. Control algorithm 460 may be implemented using any combination of program instructions and circuit components that provide the described functionality.
Controller 460 may include logic to receive inputs, perform algorithmic processing, and produce outputs. This logic may include a control loop that is implemented using either a PID controller or a PI controller. In implementations where the logic includes a PID controller, the PID controller may include a proportional gain Kp, an integrative gain Ki, and a derivative gain Kd. In implementations where the logic includes a PI controller, the PI controller may include a proportional gain Kp and an integrative gain Ki. The gains may have gas mixture concentration, temperature, and/or exhaust gas concentration as an input and a setpoint for a speed of ventilator 340 that corresponds to a volume of air as an output. The integrative gain Ki may further pass its output through an integrative accumulator. The derivative gain Kd may further pass its output through a derivative accumulator. These accumulators may refine the setpoint according to a trend of recent historical recorded values of the gas mixture concentration.
In some examples, control algorithm 460 may include a lookup table. When control algorithm 460 receives a given concentration of a gas from concentration sensor interface (e.g., the concentration of H2 in the gas), control algorithm 460 may look up the amount of air to provide to the burner for the given concentration of gas. The lookup table of control algorithm may be based on the amount of air to add to a given gas concentration to achieve efficient combustion. The lookup table may be specific to the boiler. For example, the amount of air to add to a given gas concentration may depend on the mechanics (e.g., shape and size) of the burner. However, the amount of air to add to a given gas concentration may also depend on environmental factors, such as the atmospheric pressure of the environment around the burner or the humidity of the air provided to the burner. Therefore, control algorithm 460 may use information from exhaust gas concentration sensor interface 470 to tune the lookup table in real-time. As an example, if the exhaust gas concentration indicates that the amount of air provided to the burner during a previous combustion was low, control algorithm 460 may increase the amount of air provided for subsequent combustions. This may occur when, for example, the humidity of the air provided to the burner is high.
Method 500 begins at block 505 where the controller may receive a gas concentration value indicating a concentration of one or more gases in a gas mixture. The gas mixture may be a blend of one or more gases and concentration sensor circuitry, such as concentration sensor circuitry 110 or concentration sensory circuitry 310 shown in
Next, at block 510, the controller may determine an air flow rate to input to a burner. The controller may use the gas concentration value to determine the air flow rate to provide to the burner to achieve efficient combustion. In some examples, the controller may use both the gas concentration value (received at block 510) and the indication of a concentration of gases in the exhaust from the burner (received at block 540, discussed below).
At block 515, the controller may control the air flow rate provided to the burner based on a first calculation. For example, the controller may output a control signal to a ventilator to control the operation of the ventilator (e.g., a speed of rotation of the ventilator) such that it outputs air at the air flow rate determined at block 510.
At block 520, the controller may receive a flame signal reading. The flame signal reading may be provided by flame signal reading circuitry, such as flame signal reading circuitry 170, indicating that the main flame in the burner is lit. Using the flame signal reading, at block 525, the controller may determine whether a flame exists in the burner. If a flame exists in the burner, the controller may maintain the safety valve in an open position (block 530). If a flame does not exist in the burner, at block 535, the controller may close the safety valve.
At block 540, the controller may receive an indication of a concentration of gases in the exhaust from the burner. The concentration of gases in the exhaust may be measured by an exhaust gas concentration sensor, such as exhaust gas concentration sensor 385 shown in
At block 545, the controller may receive an ambient air temperature reading.
The ambient air temperature reading may be provided to the controller by a temperature sensor, such as temperature sensor 390 shown in
At block 550, the controller may receive a temperature set point value. The temperature set point value may be provided to the controller by a thermostat.
At block 555, the controller may determine a difference between the ambient air temperature reading and the temperature set point value. At block 560, the controller may generate a burner signal to control a flame in the burner. For example, if the ambient air temperature is lower than the temperature set point value, the controller may generate a signal to instruct the burner to light. Alternatively, the controller may adjust the safety valve to control the amount of gas provided to the burner.
Although
Although examples have been described above, other variations and examples may be made from this disclosure without departing from the spirit and scope of these disclosed examples.
This application claims priority to U.S. Provisional Patent Application No. 63/603,309, filed Nov. 28, 2023, the contents of which are hereby incorporated in their entirety.
| Number | Date | Country | |
|---|---|---|---|
| 63603309 | Nov 2023 | US |
