Control method for preventing smoke blockage of heating stove

Abstract

The invention discloses a control method for preventing smoke blockage of a heating furnace, which comprises the following steps of: presetting a flame ion current intensity analog signal Ad value of smoke tube blockage as P3, a wind speed duty ratio deviation value of smoke tube blockage as P1 and a wind speed duty ratio deviation value of low voltage as P5; the current real-time flame ion current intensity analog signal value is measured as Ireal, whether Ireal is larger than P3 or not is judged, if yes, a fault is reported, the process is ended, if not, the next step is executed, the heating furnace works normally, the rotating speed of a fan is adjusted through an MCU main control chip in the heating furnace, the wind speed is stable, the actual rotating speed duty ratio of the fan is measured as Dreal, and the voltage is low; and judging whether D real-D setting is greater than P5 or whether D setting-D real-D setting is greater than P1 under the working condition of high-speed big fire under the working condition of running at the maximum wind speed, and if one of the conditions is met, reporting a fault to end the process. According to the control method provided by the invention, the smoke blockage condition can be monitored at the same time under the working conditions of high-speed big fire, low-speed small fire and low voltage, the heating furnace can be effectively closed before the smoke exceeds the standard, and the performance is stable.

Description

Technical Field

[0001] The invention relates to the technical field of heating furnaces, and in particular to a control method for preventing smoke blockage in a heating furnace. Background Art

[0002] After long-term use, the exhaust pipe of the existing heating furnace is prone to blockage. The blockage of the exhaust pipe will affect the combustion system of the heating furnace, causing the relevant parameters of the internal combustion system of the heating furnace to change and deviate from the original factory set values, which will have an adverse effect on the heating furnace equipment and affect the use of the heating furnace equipment. In order to prevent the situation where the heater is still running when the exhaust pipe is seriously blocked, existing manufacturers usually install multiple wind pressure switches and multiple wind pressure sensors in the exhaust pipe, and monitor the airflow of the exhaust pipe through multiple wind pressure switches and multiple wind pressure sensors, so as to respectively detect the changes in the air intake pressure and exhaust pressure in the exhaust pipe, so as to determine whether the exhaust pipe is blocked.

[0003] The existing exhaust pipe smoke blockage detection structure has the following shortcomings:

[0004] 1) The wind pressure switch and wind pressure sensor can only protect the heating furnace startup protection and the exhaust pipe blockage at the maximum speed of the fan, but cannot identify the blockage of low-speed and low-fire combustion during operation. Monitoring the speed of the AC fan can only identify the blockage of high-speed and high-fire combustion, but cannot identify the blockage of low-speed and low-fire combustion during operation.

[0005] 2) The monitoring of wind pressure switch and wind pressure sensor can only monitor the airflow, ignoring the influence of voltage on fan speed. When the operating voltage is lower than the rated voltage, if the smoke pipe is seriously blocked, the combustion condition will deteriorate and the smoke will exceed the standard, but the fan speed is still lower than the upper limit, the heating furnace will not shut down, which is not environmentally friendly and poses a safety hazard. Summary of the invention

[0006] In response to the technical problems existing in the prior art, the present invention provides a control method with low cost and stable performance, which can simultaneously monitor the smoke blockage situation under high-speed high-fire, low-speed low-fire and low-voltage working conditions, and can effectively shut down the heating furnace before the smoke exceeds the standard.

[0007] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0008] A control method for preventing smoke blockage in a heating furnace, the control method comprising the following steps:

[0009] Step 1) On the human-machine interface of the heating furnace, preset the flame ion current intensity analog signal Ad value of the heating furnace smoke pipe blockage as P3, the wind speed duty cycle deviation value of the smoke pipe blockage as P1, the wind speed duty cycle deviation value at low pressure as P5, and the duty cycle of the stable speed of the fan inside the heating furnace as D 设 , then go to step 2);

[0010] Step 2) The heating furnace is ignited and burned, and the current real-time flame ion current intensity analog signal value is measured to be I 实 The MCU main control chip inside the heating furnace simulates the real-time flame ion current intensity signal value I 实 It is compared with the preset flame ion current intensity analog signal Ad value P3. If the MCU main control chip determines that I 实 If the MCU main control chip determines that I 实 If it is not greater than P3, go to step 3);

[0011] Step 3) The heating furnace works normally. The MCU main control chip inside the heating furnace adjusts the speed of the fan. The wind speed is stable. The actual speed duty ratio of the fan is measured to be D 实 , proceed to step 4);

[0012] Step 4) The MCU main control chip inside the heating furnace determines D 实 -D 设 Is > P5 or D 设 -D 实 Is it > P1? If one of the conditions is met, a fault is reported and the heating furnace workflow is terminated. Otherwise, execute step 3).

[0013] As a further improvement of the above technical solution, a circuit control board is installed inside the heating furnace in step 1), and the circuit control board includes an MCU main control chip, a wind speed control and detection circuit, and a flame signal detection circuit. The wind speed control and detection circuit and the flame signal detection circuit are both electrically connected to the MCU main control chip. When the heating furnace is burning normally, P3 is 0.

[0014] As a further improvement of the above technical solution, the current real-time flame ion current intensity simulation signal value in step 2) is I 实 It is detected by the flame signal detection circuit on the internal circuit control board of the heating furnace.

[0015] As a further improvement of the above technical solution, the actual speed V of the fan in step 3) 实 The wind speed is detected by the wind speed detection circuit on the internal circuit control board of the heating furnace.

[0016] As a further improvement of the above technical solution, the heating furnace includes a heating furnace shell, a burner, a flame detection probe, and a premixer. The burner is installed at the upper end of the interior of the heating furnace shell, the flame detection probe is installed at the fire outlet of the burner, the circuit control board is installed inside the heating furnace shell and is located on one side of the burner, and the premixer is installed below the burner.

[0017] As a further improvement of the above technical solution, an air inlet pipe and a smoke exhaust pipe are provided above the heating furnace shell. The air inlet pipe is installed on one side of the smoke exhaust pipe. After entering the heating furnace shell, the air inlet pipe is connected to the premixer. After entering the heating furnace shell, the smoke exhaust pipe is connected to the air outlet of the burner.

[0018] As a further improvement of the above technical solution, a fan is installed on one side of the premixer, and the fan and the flame detection probe are electrically connected to the wind speed control and detection circuit and the flame signal detection circuit of the circuit control board respectively.

[0019] As a further improvement of the above technical solution, the heating furnace includes a gas valve and a gas inlet channel, one end of the gas inlet channel is connected to the gas valve, and the other end of the gas inlet channel is connected to the air inlet of the premixer.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] The control method of the present invention comprises presetting the flame ion current intensity analog signal Ad value of the smoke pipe blockage, the wind speed duty ratio deviation value of the smoke pipe blockage, and the wind speed duty ratio deviation value at low pressure P5, the heating furnace is ignited and burned, and the current real-time flame ion current intensity analog signal value is measured to be I 实 , determine whether I>P3, if so, report a fault and end the process, otherwise go to the next step, the heating furnace works normally, the MCU main control chip inside the heating furnace adjusts the speed of the fan, the wind speed is stable, and the actual speed duty ratio of the fan is measured to be D 实 , judge D 实 –D 设 Is > P5 or D 设- D 实 Is it>P1? If one of the conditions is met, a fault is reported and the process is terminated. The control method provided by the present invention can monitor the smoke blockage situation at high speed and high fire, low speed and low fire, and low voltage working conditions at the same time, and can effectively shut down the heating furnace before the smoke exceeds the standard, with low cost and stable performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a control flow chart of preventing smoke blockage in a heating furnace according to the present invention;

[0023] Figure 2This is a schematic diagram of the relationship between the heating furnace of the present invention, the air inlet pipe, and the smoke exhaust pipe;

[0024] Figure 3 This is a diagram showing the internal structure of the heating furnace of the present invention;

[0025] Figure 4 It is a schematic diagram of the air intake and exhaust gas emission of the heating furnace of the present invention;

[0026] Figure 5 This is the circuit principle of the MCU main control chip, wind speed control and detection circuit, and flame signal detection circuit of the present invention.

[0027] In the figure: a heating furnace shell 1, a burner 2, a flame detection probe 3, a premixer 4, a circuit control board 5, an air inlet duct 6, a smoke exhaust pipe 7, a fan 8, a gas valve 9, and a gas intake channel 10. DETAILED DESCRIPTION

[0028] The present invention is described in detail below in conjunction with the accompanying drawings, which are part of this specification and illustrate the principles of the present invention through embodiments. Other aspects, features and advantages of the present invention will become clear from the detailed description. In the drawings referred to, the same or similar parts in different figures are represented by the same reference numerals.

[0029] like Figure 1 As shown, the first embodiment of the present invention provides a control method for preventing smoke blockage in a heating furnace, and the control method includes the following steps:

[0030] Step 1) On the human-machine interface of the heating furnace, preset the flame ion current intensity analog signal Ad value of the heating furnace smoke pipe blockage as P3, the wind speed duty cycle deviation value of the smoke pipe blockage as P1, the wind speed duty cycle deviation value at low pressure as P5, and the duty cycle of the stable speed of the fan 8 inside the heating furnace as D 设 , then go to step 2);

[0031] Step 2) The heating furnace is ignited and burned, and the current real-time flame ion current intensity analog signal value is measured to be I 实 The MCU main control chip inside the heating furnace simulates the real-time flame ion current intensity signal value I 实 It is compared with the preset flame ion current intensity analog signal Ad value P3. If the MCU main control chip determines that I 实 If the MCU main control chip determines that I 实 If it is not greater than P3, go to step 3);

[0032] Step 3) The heating furnace works normally. The speed of the fan 8 is adjusted by the MCU main control chip inside the heating furnace. The wind speed is stable. The actual speed duty ratio of the fan 8 is measured to be D 实 , proceed to step 4);

[0033] Step 4) The MCU main control chip inside the heating furnace determines D 实 -D 设 Is > P5 or D 设 -D 实 Is it > P1? If one of the conditions is met, a fault is reported and the heating furnace workflow is terminated. Otherwise, execute step 3).

[0034] The present invention pre-sets the flame ion current intensity analog signal Ad value of smoke pipe blockage, the wind speed duty cycle deviation value of smoke pipe blockage, and the wind speed duty cycle deviation value at low pressure as P5, and controls the heating furnace to ignite and burn and work through the internal circuit control circuit of the heating furnace, and then adjusts the working condition of the heating hot water boiler in real time, and can simultaneously monitor the smoke blockage situation under high-speed high-fire, low-speed low-fire, and low-voltage working conditions. The control method provided by the present invention is convenient for effectively and timely shutting down the heating furnace before the exhaust pipe is blocked or the smoke exceeds the standard, which is very convenient for adjusting the heating furnace, has strong versatility, does not need to design too many or redundant mechanical action parts, has less drift of the blockage protection point, and has more stable and reliable performance.

[0035] like Figure 2-5 As shown, when the present invention is specifically implemented, in step 1), a circuit control board 5 is installed inside the heating furnace, and the circuit control board 5 includes an MCU main control chip, a wind speed control and detection circuit, and a flame signal detection circuit. The wind speed control and detection circuit and the flame signal detection circuit are both electrically connected to the MCU main control chip. When the heating furnace is burning normally, P3 is 0, and the current real-time flame ion current intensity analog signal value in step 2) is I 实 The detection is performed by the flame signal detection circuit on the internal circuit control board 5 of the heating furnace. In the specific implementation, when the fire is started in step 2), the heating furnace burns slowly with a small fire. After 60S, the MCU main control chip can detect the current flame ion current intensity analog signal value I in real time through the flame signal detection circuit. 实 If the MCU main control chip detects the current flame ion current intensity analog signal value I 实 If it is greater than P3, a fault is reported and the heating furnace is turned off, otherwise proceed to the next step, i.e. step 3).

[0036] Regarding the actual speed V of the fan 8 in step 3) of the present invention 实 The wind speed is detected by the wind speed detection circuit on the internal circuit control board 5 of the heating furnace. As the temperature of the heating furnace changes, the speed duty ratio of the fan 8 is D 实There will also be corresponding changes.

[0037] When the embodiment of the present invention is specifically implemented, the heating furnace includes a heating furnace shell 1, a burner 2, a flame detection probe 3, and a premixer 4. The burner 2 is installed at the upper end of the interior of the heating furnace shell 1, the flame detection probe 3 is installed at the fire outlet of the burner 2, the circuit control board 5 is installed inside the heating furnace shell 1 and is located on one side of the burner 2, the premixer 4 is installed below the burner 2, and an air inlet pipe 6 and a smoke exhaust pipe 7 are provided above the heating furnace shell 1. The air inlet pipe 6 is installed on one side of the smoke exhaust pipe 7. , the air inlet pipe 6 is connected to the premixer 4 after entering the heating furnace shell 1, the smoke exhaust pipe 7 is connected to the air outlet of the burner 2 after entering the heating furnace shell 1, a fan 8 is installed on one side of the premixer 4, the fan 8 and the flame detection probe 3 are electrically connected to the wind speed control and detection circuit and the flame signal detection circuit of the circuit control board 5 respectively, the heating furnace of the present invention comprises a gas valve 9 and a gas intake channel 10, one end of the gas intake channel 10 is connected to the gas valve 9, and the other end of the gas intake channel 10 is connected to the air inlet of the premixer 4. The present invention detects the flame current through the flame detection probe 3, and sends the flame current signal to the main control chip of the circuit control board 5 through the flame signal detection circuit on the circuit control board 5, and the main control chip of the circuit control board 5 can monitor the combustion condition of the burner 2 to determine whether the burner 2 meets the good combustion range, thereby adjusting the number of revolutions of the fan 8.

[0038] In an embodiment of the present invention, the wind speed control and detection circuit includes a fan connection socket CN1, a resistor R4, a diode ZD1, a resistor R21, a transistor Q2, a resistor R5, a transistor Q1, a resistor R12, a resistor R1, and a resistor R3, one end of the resistor R12 is electrically connected to the MCU main control chip, the other end of the resistor R12 is electrically connected to the base of the transistor Q1, one end of the resistor R1 is electrically connected to the second pin of the fan connection socket CN1, and one end of the resistor R3 is electrically connected to the fifth pin of the fan connection socket CN1. The other end of the resistor R1 is connected in parallel with the other end of the resistor R3 and then electrically connected to the collector of the transistor Q1 to realize the electrical connection between the transistor Q1 and the connection base of the fan 8. One end of the resistor R5 is electrically connected to the MCU main control chip, and the other end of the resistor R5 is electrically connected to the collector of the transistor Q2. The base of the transistor Q2 is electrically connected to the resistor R21, the diode ZD1, and one end of the resistor R4 in sequence, and the other end of the resistor R4 is electrically connected to the 4th pin of the fan connection base CN1 to realize the electrical connection between the transistor Q2 and the connection base of the fan 8. In specific implementation, the models of the transistors Q2 and Q1 in the wind speed control and detection circuit of the present invention are both MMBT5551. The wind speed control and detection circuit of the present invention is electrically connected to the fan 8 through the fan connecting socket CN1. The wind speed control and detection circuit will measure the real-time wind speed of the fan 8 and send the measured real-time wind speed signal to the MCU main control chip. The wind speed detection circuit is used to detect the real-time rotation speed of the fan 8 and transmit the detected real-time rotation speed data signal to the MCU main control chip. The MCU main control chip will send a signal to the wind speed control and detection circuit according to the received real-time rotation speed data signal, and the wind speed control and detection circuit will adjust the rotation speed of the fan 8.

[0039] In specific implementation, the flame signal detection circuit of the present invention includes a resistor R30, a resistor R34, a high-speed switching diode D1, a transistor Q7, a resistor R37, a resistor R38, a resistor R39, and a fire detection probe PT1. The fire detection probe PT1 is electrically connected to the resistor R39, the resistor R38, and one end of the resistor R37 in sequence, the other end of the resistor R37 is electrically connected to the emitter of the transistor Q7, the collector of the transistor Q7 is electrically connected to one end of the high-speed switching diode D1, the resistor R34, and one end of the resistor R30 in sequence, and the other end of the resistor R30 is electrically connected to the MCU main control chip.

[0040] The flame signal detection circuit of the present invention is electrically connected to the flame detection probe 3 through the flame detection probe PT1, and the flame detection probe 3 collects the current flame ion current intensity analog signal value I 实 And collect the current flame ion current intensity analog signal value I 实 Sent to the MCU main control chip.

[0041] In specific implementation, the present invention needs to determine whether the wind speed duty cycle deviation value of the fan 8 is greater than the preset value in step 4). 实 -D 设 Is > P5 or D 设 -D 实 Is it > P1), there are two main reasons. The first one is that when the air inlet and / or the exhaust port is gradually blocked, the load of the fan 8 will inevitably decrease and the speed of the fan 8 will increase. Because the fan 8 is a constant speed fan 8, the MCU main control chip adjusts and reduces the duty cycle of the PWM output by the wind speed control and detection circuit, so that the speed of the fan 8 remains at the original speed. When D 设 -D 实 >P1(where D 设 It is the data obtained through experiments and set through the human-machine interface. 设 , which can also be reset by adjusting the wind speed), indicating that the heating furnace exhaust pipe is seriously blocked, and then the MCU main control chip closes the gas valve, so that the wall-mounted heating furnace meets the national inspection standards. The second type: When the city power is lower than 170V, it will inevitably cause the speed of fan 8 to decrease. Because fan 8 is a constant speed fan 8, the MCU main control chip adjusts and increases the duty cycle of the PWM output by the wind speed control and detection circuit, so that the speed of fan 8 remains at the original speed. When D 实 -D 设 >P5, indicating that the mains voltage was too low and not suitable for normal operation. For safety reasons, the MCU main control chip closed the gas valve.

[0042] The above description has been a detailed description of the present invention. The above description is only a preferred embodiment of the present invention and should not limit the scope of implementation of the present application. That is, all equivalent changes and modifications made within the scope of the present application should still fall within the scope of the present invention.

Claims

1. A control method for preventing smoke blockage in a heating furnace, characterized in that: The control method comprises the following steps: Step 1) On the human-machine interface of the heating furnace, preset the flame ion current intensity analog signal Ad value of the heating furnace smoke pipe blockage as P3, the wind speed duty cycle deviation value of the smoke pipe blockage as P1, the wind speed duty cycle deviation value at low pressure as P5, and the duty cycle of the stable speed of the fan inside the heating furnace as D 设 , then go to step 2); Step 2) The heating furnace is ignited and burned, and the current real-time flame ion current intensity analog signal value is measured to be I 实 The MCU main control chip inside the heating furnace simulates the real-time flame ion current intensity signal value I 实 It is compared with the preset flame ion current intensity analog signal Ad value P3. If the MCU main control chip determines that I 实 If the MCU main control chip determines that I 实 If it is not greater than P3, go to step 3); Step 3) The heating furnace works normally. The MCU main control chip inside the heating furnace adjusts the speed of the fan. The wind speed is stable. The actual speed duty ratio of the fan is measured to be D 实 , proceed to step 4); Step 4) The MCU main control chip inside the heating furnace determines D 实 -D 设 Is > P5 or D 设 -D 实 Is it > P1? If one of the conditions is met, a fault is reported and the heating furnace workflow is terminated. Otherwise, execute step 3).

2. The control method for preventing smoke blockage of a heating furnace according to claim 1, characterized in that: The heating furnace described in step 1) is internally installed with a circuit control board, which includes an MCU main control chip, a wind speed control and detection circuit, and a flame signal detection circuit. The wind speed control and detection circuit and the flame signal detection circuit are both electrically connected to the MCU main control chip. When the heating furnace is burning normally, P3 is 0.

3. The control method for preventing smoke blockage of a heating furnace according to claim 1, characterized in that: The current real-time flame ion current intensity analog signal value in step 2) is I 实 It is detected by the flame signal detection circuit on the internal circuit control board of the heating furnace.

4. The control method for preventing smoke blockage of a heating furnace according to claim 1, characterized in that: Step 3) The actual speed V of the fan 实 It is detected by the wind speed detection circuit on the internal circuit control board of the heating furnace.

5. The control method for preventing smoke blockage in a heating furnace according to claim 3 is characterized in that: The heating furnace includes a heating furnace shell, a burner, a flame detection probe, and a premixer. The burner is installed at the upper end of the interior of the heating furnace shell, the flame detection probe is installed at the fire outlet of the burner, the circuit control board is installed inside the heating furnace shell and is located on one side of the burner, and the premixer is installed below the burner.

6. The control method for preventing smoke blockage of a heating furnace according to claim 5, characterized in that: An air inlet pipe and a smoke exhaust pipe are provided above the heating furnace shell. The air inlet pipe is installed on one side of the smoke exhaust pipe. After entering the heating furnace shell, the air inlet pipe is connected to the premixer. After entering the heating furnace shell, the smoke exhaust pipe is connected to the air outlet of the burner.

7. The control method for preventing smoke blockage in a heating furnace according to claim 5, characterized in that: A fan is installed at one side of the premixer, and the fan and the flame detection probe are electrically connected to the wind speed control and detection circuit and the flame signal detection circuit of the circuit control board respectively.

8. The control method for preventing smoke blockage of a heating furnace according to claim 5, characterized in that: The heating furnace comprises a gas valve and a gas inlet passage, one end of the gas inlet passage is connected to the gas valve, and the other end of the gas inlet passage is connected to the air inlet of the premixer.

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