Combustion-supporting air volume meter heating and drying device for natural gas boiler and control circuit

Abstract

The invention belongs to the technical field of natural gas boiler auxiliary equipment, and particularly relates to a combustion-supporting air volume meter heating and drying device for a natural gas boiler and a control circuit, the device comprises a boiler body, an air preheater, an air blower, a heater, an induced draft fan and a combustion-supporting air volume meter, the air preheater is connected with an inlet and an outlet of the boiler body through pipelines. One end of the blower is connected to an inlet of the air preheater, the other end of the blower is communicated with the outside through an air duct, and the air duct comprises a heating section and a confluence section; the heater is mounted in the heating section of the blower inlet air duct; one end of the induced draft fan is connected to a smoke outlet of the air preheater, and the other end is communicated with the confluence section of the air duct; and the combustion-supporting air volume meter is arranged on a pipeline connected between the air preheater and the air blower. The heating and drying device prevents combustion-supporting air at a measurement point of the natural gas boiler air meter from containing moisture, ensures the accuracy of air quantity measurement, and enables the measurement of the air meter to meet the requirement of a boiler combustion automatic mode.

Description

Technical Field

[0001] The invention belongs to the technical field of natural gas boiler auxiliary equipment, and in particular relates to a heating and drying device and a control circuit of a combustion-supporting air flow meter for a natural gas boiler. Background Art

[0002] Natural gas boilers are widely used in modern industrial production to provide stable and efficient heat energy. During the operation of natural gas boilers, the supply of combustion air is one of the key factors to ensure combustion efficiency and environmental emission standards. Combustion air refers to the air supplied to the combustion chamber during the combustion process, which directly affects the integrity of the combustion reaction and the combustion efficiency.

[0003] Traditional natural gas boiler combustion systems are usually equipped with air flow meters to measure and control the amount of air entering the combustion chamber. However, these air flow meters are easily affected by the outside temperature and humidity in winter or low temperature environments, resulting in inaccurate measurement data. The high water vapor content in low temperature air will form condensation on the air flow meter sensor, which not only affects the accuracy of the data, but may also cause damage to the equipment.

[0004] In addition, the existing combustion air system fails to effectively solve the condensation problem caused by large changes in ambient temperature. When the combustion air is mixed with the flue gas, a large amount of condensation water is easily generated due to the dew point, which not only affects the measurement accuracy of the combustion air flow meter, but also accelerates the corrosion of the equipment, reducing the overall safety and operating life of the system.

[0005] Therefore, there is an urgent technical demand for improvement, namely, to develop a natural gas boiler combustion air heating and drying device that can effectively prevent condensation, improve measurement accuracy and extend the service life of the equipment. Summary of the invention

[0006] 1. Technical issues to be resolved

[0007] The present invention mainly aims at the above problems and proposes a heating and drying device and a control circuit for a combustion air volume meter for a natural gas boiler, the purpose of which is to solve the problems of inaccurate measurement and equipment condensation caused by high ambient humidity in winter or low temperature environments.

[0008] (II) Technical solution

[0009] To achieve the above-mentioned object, the first aspect of the present invention provides a combustion air flow meter heating and drying device for a natural gas boiler, comprising:

[0010] Boiler body;

[0011] An air preheater, which is connected to the inlet and outlet of the boiler body through pipelines, and is used to heat the air entering the boiler body and discharge the flue gas after heat exchange;

[0012] A blower, one end of which is connected to the inlet of the air preheater and is used to provide combustion-supporting air to the inlet of the boiler body, and the other end of the blower is connected to the outside through an air duct, and the air duct includes a heating section and a converging section;

[0013] A heater, installed in a heating section of the blower inlet duct, for heating the air entering the blower;

[0014] An induced draft fan, one end of which is connected to the smoke outlet of the air preheater, and the other end of which is connected to the converging section of the air duct;

[0015] The combustion-supporting air volume meter is installed on the pipeline connecting the air preheater and the blower.

[0016] Furthermore, the heater includes two sets of independent heating units, namely a first heating unit and a second heating unit, wherein:

[0017] The first heating unit always operates under normal conditions;

[0018] The second heating unit is started when the outdoor temperature is extremely low, and the first heating unit and the second heating unit serve as backup for each other.

[0019] Further, the heater is connected to a control circuit, and the control circuit comprises:

[0020] A power module, used to provide power to the entire control circuit;

[0021] A conversion switch, having two gears, a manual mode and an automatic mode, connected to the power module, receiving power, the conversion switch comprising a first contact group and a second contact group, and controlling different working modes of the circuit through the first contact group and the second contact group;

[0022] A start button connected to a first contact group of the transfer switch;

[0023] The stop button is used to stop the heater in manual and automatic modes, and forms a circuit with the start button and the output contact of the temperature controller respectively;

[0024] A solid-state relay, one end of which is connected to the normally closed contact of the thermal relay, and the other end of which is connected to the stop button;

[0025] An intermediate relay, one end of which is connected to the normally closed contact of the thermal relay, and the other end of which is connected to the stop button, forming a parallel circuit with the solid-state relay;

[0026] A temperature controller receives the temperature signal from the thermal resistor and adjusts the heating time of the heater by controlling the solid-state relay, wherein one end of the output contact is connected to the second contact group of the conversion switch, and the other end of the output contact is connected between the start button and the stop button;

[0027] The thermal resistor is installed at the outlet of the heating section, and is used to detect the air temperature and transmit the temperature signal to the temperature controller, and its signal output end is connected to the input end of the temperature controller.

[0028] Furthermore, the intermediate relay acts as a latching relay, and a normally open contact is connected to the input side of the start button to form a bypass loop, which is closed when the intermediate relay coil is energized, and another normally closed contact is closed when the intermediate relay coil is de-energized and connected to the heater stop indicator light, which is connected to the input side of the start button.

[0029] Furthermore, a heater start indicator light is included, and the heater start indicator light is connected to the output side of the stop button.

[0030] Furthermore, it also includes a thermal relay for cutting off the circuit and issuing a fault indication when the heater is overheated, and a normally closed contact of the thermal relay is installed on the output side of the solid-state relay.

[0031] Furthermore, it also includes a fault indicator light. A normally open contact of the thermal relay is installed to close after the heater is overheated and is connected to the fault indicator light. The fault indicator light is connected to the input side of the start button.

[0032] Furthermore, the air duct is provided with a drain outlet, the drain outlet is provided with a drain valve, and the drain outlet is located at the outlet of the heating section.

[0033] To achieve the above object, the second aspect of the present invention provides a heater control circuit for a natural gas boiler combustion-supporting air flow meter, comprising:

[0034] A power module, used to provide power to the entire control circuit;

[0035] A conversion switch, having two gears, a manual mode and an automatic mode, connected to the power module, receiving power, the conversion switch comprising a first contact group and a second contact group, and controlling different working modes of the circuit through the first contact group and the second contact group;

[0036] A start button connected to a first contact group of the transfer switch;

[0037] The stop button is used to stop the heater in manual and automatic modes, and forms a circuit with the start button and the output contact of the temperature controller respectively;

[0038] A solid-state relay, one end of which is connected to the normally closed contact of the thermal relay, and the other end of which is connected to the stop button;

[0039] An intermediate relay, one end of which is connected to the normally closed contact of the thermal relay, and the other end of which is connected to the stop button, forming a parallel circuit with the solid-state relay;

[0040] A temperature controller receives the temperature signal from the thermal resistor and adjusts the heating time of the heater by controlling the solid-state relay, wherein one end of the output contact is connected to the second contact group of the conversion switch, and the other end of the output contact is connected between the start button and the stop button;

[0041] The thermal resistor is installed at the outlet of the heating section, and is used to detect the air temperature and transmit the temperature signal to the temperature controller, and its signal output end is connected to the input end of the temperature controller.

[0042] Further, the intermediate relay acts as a latching relay, a normally open contact is connected to the input side of the start button to form a bypass loop, which is closed when the intermediate relay coil is energized, and another normally closed contact is closed when the intermediate relay coil is de-energized and connected to the heater stop indicator light, which is connected to the input side of the start button;

[0043] The control circuit includes a heater start indicator light, a thermal relay, and a fault indicator light. The heater start indicator light is connected to the output side of the stop button; the thermal relay is used to cut off the circuit and issue a fault indication when the heater is overheated, and a normally closed contact of the thermal relay is installed on the output side of the solid-state relay; a normally open contact of the thermal relay is installed to close after the heater is overheated and is connected to the fault indicator light, and the fault indicator light is connected to the input side of the start button.

[0044] (III) Beneficial effects

[0045] Compared with the prior art, the present invention provides a heating and drying device and a control circuit for a combustion-supporting air volume meter for a natural gas boiler. By adding a heating and drying device to the blower inlet of the boiler body, the heated high-temperature air is mixed with the return flue gas without producing condensation, thereby achieving the purpose of accurate air volume measurement. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 This is a structural schematic diagram of a heating and drying device for a combustion-supporting air volume meter for a natural gas boiler disclosed in this application.

[0047] Figure 2 This is a control circuit diagram of a heater 1 disclosed in this application.

[0048] Figure 3 This is a control circuit diagram of a heater 2 disclosed in this application.

[0049] Figure 4 This is a general power supply diagram of a heating system disclosed in this application.

[0050] The reference numerals shown in the figure are: 1. boiler body; 2. air preheater; 3. blower; 4. heater; 5. induced draft fan; 6. combustion air volume meter; 7. heating section; 8. confluence section; 9. thermal resistor; 10. drain valve. DETAILED DESCRIPTION

[0051] The present invention will be described in detail below in conjunction with the accompanying drawings, and the technical solutions in the embodiments of the present invention will be clearly and completely described. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0052] It should be noted that when a component is referred to as being "fixed to" another component, it may be directly on the other component or there may also be a component centered. When a component is considered to be "connected to" another component, it may be directly connected to the other component or there may also be a component centered. When a component is considered to be "set on" another component, it may be directly set on the other component or there may also be a component centered. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only.

[0053] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0054] See also Figure 1 The figure is a schematic diagram of the structure of a heating and drying device for a combustion air volume meter for a natural gas boiler provided by a preferred embodiment of the present application. Figure 1 In the embodiment shown, the main components of the device include:

[0055] The boiler body 1, as the core of the system, is responsible for the combustion of natural gas and the generation of heat energy;

[0056] The air preheater 2 is connected to the inlet and outlet of the boiler body 1 through pipelines. Its main function is to preheat the air entering the boiler body 1 and safely discharge the flue gas after heat exchange;

[0057] The blower 3, one end of which is connected to the inlet of the air preheater 2, is responsible for sending the heated and dried air into the boiler body 1 to support the combustion process. The other end of the blower 3 is connected to the outside through an air duct, which is divided into a heating section 7 and a converging section 8;

[0058] The heater 4 is arranged in the air duct heating section 7 at the inlet of the blower 3, and is mainly used to heat the air entering the blower 3 to ensure that the air does not cause measurement errors of the air volume meter in a low temperature environment;

[0059] The induced draft fan 5 is connected to the smoke outlet of the air preheater 2, and the other end thereof is connected to the converging section 8 of the air duct;

[0060] The combustion-supporting air volume meter 6 is installed on the pipeline connecting the air preheater 2 and the blower 3, and is used to accurately measure the combustion-supporting air volume entering the boiler body 1 to ensure combustion efficiency and environmental safety.

[0061] The design of this embodiment not only optimizes the utilization efficiency of thermal energy, but also reduces energy consumption by precisely controlling the heating process, and can effectively prevent water vapor in the cold air from condensing on the sensor of the combustion-supporting air volume meter 6, thereby ensuring the accuracy of the measurement of the combustion-supporting air volume meter 6.

[0062] In this embodiment, the heater 4 is designed to include two independent heating units: a first heating unit and a second heating unit, which optimizes the operating efficiency of the equipment under different environmental conditions. The first heating unit is responsible for continuous operation under normal climatic conditions to ensure that the air intake of the blower 3 always maintains a suitable temperature. When encountering extremely low temperature weather, the second heating unit will automatically start to provide additional heating power to ensure the stability and efficiency of the system. In addition, the two heating units are designed to be in standby status with each other. When one unit is repaired or fails, the other unit can immediately take over the work, thereby seamlessly maintaining the continuity and reliability of operation. This flexible configuration enhances the system's adaptability in the face of different temperature changes and significantly improves the operating efficiency and safety of the equipment.

[0063] like Figure 2-Figure 4 As shown, the heater 4 is managed by a control circuit, which ensures that the heating system can automatically or manually adjust the operating mode according to different environmental conditions. The following are the main components and functions of the control circuit:

[0064] Power module: responsible for providing the required power to the control circuit.

[0065] Conversion switch SA1, SA2: It has two operating positions: manual mode and automatic mode. The conversion switch SA1, SA2 is directly connected to the power module, and the working mode of the heater can be selected according to the operating requirements. The conversion switch SA1, SA2 includes two groups of contacts, the first contact group 1, 2 and the second contact group 3, 4, which respectively control different working states of the circuit.

[0066] Start button SB1, SB3: connected to the first contact group 1, 2 of the conversion switch SA1, SA2, used to start the operation of the heater.

[0067] Stop buttons SB2, SB4: In manual and automatic modes, the stop buttons SB2, SB4 are used to stop the operation of the heater, and together with the start buttons SB1, SB3 and the output contacts of the temperature controller, they constitute an operating circuit.

[0068] Solid-state relays SSR1, SSR2: One end is connected to the normally closed contact KH1 of the thermal relay, and the other end is connected to the stop button.

[0069] Intermediate relays KA1, KA2: connected in parallel with solid-state relays SSR1, SSR2, and also connected to the normally closed contacts of the thermal relay and stop buttons SB2, SB4.

[0070] Temperature controller: Receives temperature signal from thermal resistor 9. Adjusts the working time of the heater according to the detected temperature to ensure that the air is heated to a suitable temperature. The input end of the temperature controller is connected to the second contact group 3, 4 of the conversion switch SA1, SA2, and the output end is connected between the start button SB1, SB3 and the stop button SB2, SB4, forming a temperature control loop.

[0071] Thermal resistor 9: installed at the outlet of heating section 7, used to monitor the temperature of the air after being heated by the heater in real time and transmit this temperature information to the temperature controller.

[0072] By adding a set of heater control circuits in the inlet air duct of the blower 3, a thermistor 9 is installed at the outlet of the heater, and the signal of the thermistor 9 is connected to the temperature controller (refer to the Yudian AI208 series). The advantage of this is that the heating time of the heater can be controlled by setting the temperature value of the thermostat, so as to achieve the purpose of drying and heating the cold air and making the combustion air volume meter measure accurately.

[0073] In this embodiment, the application of the intermediate relay greatly improves the operation convenience and continuity of the heating system. Figure 2As shown in the figure, when the operator presses the start button SB1, the intermediate relay KA1 and the solid-state relay SSR1 are activated, thereby starting the heater. At this time, the start button SB1 only needs to be pressed briefly, and thanks to the design that the intermediate relay KA1 closes quickly after being energized, a bypass circuit is immediately formed. This means that even if the operator releases the start button SB1, the heater remains in operation due to the existence of the bypass circuit.

[0074] This design ensures continuity and safety during operation, allowing the heater to continue to operate without continuously manually pressing the start button. In addition, the normally closed contacts of the intermediate relay are closed after power failure and connected to the stop indicator light of the heater, which in this embodiment is connected to the input side of the start button. This provides important visual feedback, allowing the operator to clearly see when the heater is stopped, further enhancing the safety and intuitiveness of operation.

[0075] The circuit of this embodiment is provided with a plurality of indicator lights, such as heater start indicator lights H1, H3 and heater fault indicator lights H5, H6. The heater start indicator lights H1, H3 are connected to the output side of the stop buttons SB2, SB4 to provide immediate start status feedback. The heater fault indicator lights H5, H6 are connected to the normally open contacts of the thermal relays KH1, KH2. When the heater overheats and causes the thermal relays KH1, KH2 to operate, the heater fault indicator lights H5, H6 will light up to warn the operator to take corresponding measures.

[0076] The control circuit of this embodiment also includes thermal relays KH1 and KH2, which are used to automatically cut off the circuit when the heater is overheated to prevent damage to the equipment. The normally closed contacts of the thermal relays KH1 and KH2 are installed on the output side of the solid-state relays SSR1 and SSR2 to quickly disconnect the power supply of the heater in an emergency.

[0077] Preferably, a drain port is provided at the outlet of the heating section 7 of the air duct, and a drain valve 10 is provided to drain condensed water that may be generated during the heating process. This not only helps to keep the inside of the air duct dry, but also prevents water vapor from corroding the equipment.

[0078] The heating and drying device for the combustion-supporting air flow meter of a natural gas boiler provided in this embodiment can effectively prevent the water vapor in the cold air from condensing on the combustion-supporting air flow meter 6 sensor by introducing a specially designed heating system, thereby ensuring the accuracy of the air flow meter measurement. This system includes two sets of heating units, one of which operates continuously under normal conditions, and the other is started under extremely low external temperature conditions to provide additional heating to ensure that the performance of the air flow meter is not affected under all climatic conditions. In addition, the equipped control circuit can automatically adjust the heating time through the use of a temperature controller and a thermal resistor to ensure the optimization of the heating effect, and also includes a fault indication system to improve the safety of the equipment and the convenience of maintenance. This innovative design not only improves the reliability and efficiency of the system, but also extends the service life of the equipment and reduces maintenance costs.

[0079] This embodiment also provides a heater control circuit for a natural gas boiler combustion-supporting air flow meter, the control circuit comprising:

[0080] A power module, used to provide power to the entire control circuit;

[0081] A conversion switch, having two gears, a manual mode and an automatic mode, connected to the power module, receiving power, the conversion switch comprising a first contact group and a second contact group, and controlling different working modes of the circuit through the first contact group and the second contact group;

[0082] A start button connected to a first contact group of the transfer switch;

[0083] The stop button is used to stop the heater in manual and automatic modes, and forms a circuit with the start button and the output contact of the temperature controller respectively;

[0084] A solid-state relay, one end of which is connected to the normally closed contact of the thermal relay, and the other end of which is connected to the stop button;

[0085] An intermediate relay, one end of which is connected to the normally closed contact of the thermal relay, and the other end of which is connected to the stop button, forming a parallel circuit with the solid-state relay;

[0086] A temperature controller receives the temperature signal from the thermal resistor and adjusts the heating time of the heater by controlling the solid-state relay, wherein one end of the output contact is connected to the second contact group of the conversion switch, and the other end of the output contact is connected between the start button and the stop button;

[0087] A thermal resistor, installed at the outlet of the heating section, used to detect the air temperature and transmit a temperature signal to the temperature controller, and a signal output end thereof is connected to an input end of the temperature controller;

[0088] The intermediate relay acts as a latching relay, with one normally open contact connected to the input side of the start button to form a bypass loop, which is closed when the intermediate relay coil is energized, and the other normally closed contact is closed when the intermediate relay coil is de-energized and connected to the heater stop indicator light, which is connected to the input side of the start button;

[0089] The control circuit includes a heater start indicator light and a thermal relay fault indicator light, and the heater start indicator light is connected to the output side of the stop button; the thermal relay is used to cut off the circuit and issue a fault indication when the heater is overheated, and a normally closed contact of the thermal relay is installed on the output side of the solid-state relay; a normally open contact of the thermal relay is installed and closed after the heater is overheated, and is connected to the fault indicator light, and the fault indicator light is connected to the input side of the start button.

[0090] The heater has two control modes, manual control mode and temperature controller automatic control mode. Take heater 1 as an example. Figure 2 As shown, the circuit breaker QF6 is closed. When the transfer switch SA1 is turned to the manual position, the first contact group 1 and 2 of the transfer switch SA1 are closed, and the second contact group 3 and 4 are disconnected. When the start button SB1 is pressed, the intermediate relay KA1 and the solid-state relay SSR1 at the rear are energized, and the heater starts. KH1 is the normally closed contact of the thermal relay, which plays a protective role in the circuit. H1 and H2 are the indicator lights for the start and stop of the heater, and H5 is the indicator light for the heater failure. After the intermediate relay KA1 is energized, the normally open contact KA1 in front is closed, and the normally closed contact KA1 is disconnected. At this time, the heater start indicator light H1 is on, and the heater stop indicator light is off. When the heater fails and overheats, the normally closed contact of the thermal relay KH1 is disconnected, the heater stops working, and the normally open contact of the thermal relay KH1 is closed. At this time, the heater fault indicator light H5 is on. When you need to stop, you can press the stop button SB2 to disconnect the stop button SB2, and then it returns to the initial state.

[0091] When the switch SA1 is turned to the automatic position, the second contact group 3 and 4 of the switch SA1 are closed, the contacts of the temperature controller output are closed, the intermediate relay KA1 and the solid-state relay SSR1 are energized, and the heater starts. (When the temperature set by the heater temperature controller is higher than the input ambient temperature, the output normally open contacts of the temperature controller will be closed) Heater 2 (see Figure 3 ) has the same working principle as heater 1.

[0092] In the automatic control mode, the temperature value at the heater outlet is T, the temperature value set by the temperature controller of heater 1 is T1, the hysteresis is T2, and the temperature value set by the temperature controller of heater 2 is T3. T < T1 < T3. Both heater 1 and heater 2 will start and quickly heat the air in the suction pipe. When the temperature T at the heater outlet rises to the temperature T1, heater 1 stops, and heater 2 continues to operate until the temperature reaches T3, then heater 2 will stop. In fact, with only one heater running, the set temperature value of T3 cannot be reached at the outlet temperature. So heater 2 will keep running. When the load increases, the air volume increases, or the outdoor temperature is extremely low, the outlet temperature will drop to less than T1 - T2. At this time, heater 1 will restart, so that the outlet temperature T can be maintained between T1 and T3 to meet the temperature requirements.

[0093] Therefore, from any perspective, the embodiments should be regarded as exemplary and non-limiting. The scope of the present application is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the present application. Any reference signs in the claims should not be construed as limiting the corresponding claims. In addition, it is obvious that the term "comprising" does not exclude other units or steps, and the singular does not exclude the plural. The multiple units or devices stated in the apparatus claims can also be implemented by the same unit or device through software or hardware. The terms "first", "second", etc. are used to denote names and do not denote any particular order.

[0094] The above embodiments are only used to illustrate the technical solutions of the present application and are not restrictive. Although the present application has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present application can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present application.

Claims

1. A heating and drying device for a combustion air flow meter of a natural gas boiler, characterized in that: include: Boiler body; An air preheater, which is connected to the inlet and outlet of the boiler body through pipelines, and is used to heat the air entering the boiler body and discharge the flue gas after heat exchange; A blower, one end of which is connected to the inlet of the air preheater and is used to provide combustion-supporting air to the inlet of the boiler body, and the other end of the blower is connected to the outside through an air duct, and the air duct includes a heating section and a converging section; A heater, installed in a heating section of the blower inlet duct, for heating the air entering the blower; An induced draft fan, one end of which is connected to the smoke outlet of the air preheater, and the other end of which is connected to the converging section of the air duct; The combustion air volume meter is installed on the pipeline connecting the air preheater and the blower.

2. The heating and drying device for a combustion air flow meter for a natural gas boiler according to claim 1 is characterized in that: The heater comprises two sets of independent heating units, namely a first heating unit and a second heating unit, wherein: The first heating unit always operates under normal conditions; The second heating unit is started when the outdoor temperature is extremely low, and the first heating unit and the second heating unit serve as backup for each other.

3. The heating and drying device for a combustion air flow meter for a natural gas boiler according to claim 1 is characterized in that: The heater is connected to a control circuit, and the control circuit comprises: A power module, used to provide power to the entire control circuit; A conversion switch, having two gears, manual mode and automatic mode, connected to the power module, receiving power, the conversion switch comprising a first contact group and a second contact group, and controlling different working modes of the circuit through the first contact group and the second contact group; A start button connected to a first contact group of the transfer switch; The stop button is used to stop the heater in manual and automatic modes, and forms a circuit with the start button and the output contact of the temperature controller respectively; A solid-state relay, one end of which is connected to the normally closed contact of the thermal relay, and the other end of which is connected to the stop button; An intermediate relay, one end of which is connected to the normally closed contact of the thermal relay, and the other end of which is connected to the stop button, forming a parallel circuit with the solid-state relay; A temperature controller receives the temperature signal from the thermal resistor and adjusts the heating time of the heater by controlling the solid-state relay, wherein one end of the output contact is connected to the second contact group of the conversion switch, and the other end of the output contact is connected between the start button and the stop button; The thermal resistor is installed at the outlet of the heating section, and is used to detect the air temperature and transmit the temperature signal to the temperature controller, and its signal output end is connected to the input end of the temperature controller.

4. A heating and drying device for a combustion air flow meter for a natural gas boiler according to claim 3, characterized in that: The intermediate relay acts as a latching relay, and a normally open contact is connected to the input side of the start button to form a bypass loop, which is closed when the intermediate relay coil is energized, and the other normally closed contact is closed when the intermediate relay coil is de-energized and is connected to the heater stop indicator light, which is connected to the input side of the start button.

5. The heating and drying device for a combustion air flow meter for a natural gas boiler according to claim 4, characterized in that: A heater start indicator light is also included, and the heater start indicator light is connected to the output side of the stop button.

6. A heating and drying device for a combustion air flow meter for a natural gas boiler according to claim 5, characterized in that: It also includes a thermal relay for cutting off the circuit and issuing a fault indication when the heater is overheated, and a normally closed contact of the thermal relay is installed on the output side of the solid-state relay.

7. A heating and drying device for a combustion air flow meter for a natural gas boiler according to claim 6, characterized in that: It also includes a fault indicator light. A normally open contact of the thermal relay is installed to close after the heater is overheated and is connected to the fault indicator light. The fault indicator light is connected to the input side of the start button.

8. The heating and drying device for a combustion air flow meter for a natural gas boiler according to claim 1, characterized in that: The air duct is also provided with a drain outlet, on which a drain valve is provided, and the drain outlet is located at the outlet of the heating section.

9. A heater control circuit for a natural gas boiler combustion air flow meter, characterized in that: The control circuit comprises: A power module, used to provide power to the entire control circuit; A conversion switch, having two gears, manual mode and automatic mode, connected to the power module, receiving power, the conversion switch comprising a first contact group and a second contact group, and controlling different working modes of the circuit through the first contact group and the second contact group; A start button connected to a first contact group of the transfer switch; The stop button is used to stop the heater in manual and automatic modes, and forms a circuit with the start button and the output contact of the temperature controller respectively; A solid-state relay, one end of which is connected to the normally closed contact of the thermal relay, and the other end of which is connected to the stop button; An intermediate relay, one end of which is connected to the normally closed contact of the thermal relay, and the other end of which is connected to the stop button, forming a parallel circuit with the solid-state relay; A temperature controller receives the temperature signal from the thermal resistor and adjusts the heating time of the heater by controlling the solid-state relay, wherein one end of the output contact is connected to the second contact group of the conversion switch, and the other end of the output contact is connected between the start button and the stop button; The thermal resistor is installed at the outlet of the heating section, and is used to detect the air temperature and transmit the temperature signal to the temperature controller, and its signal output end is connected to the input end of the temperature controller. The heater control circuit for a natural gas boiler combustion-supporting air flow meter according to claim 9 is characterized in that: The intermediate relay acts as a latching relay, with one normally open contact connected to the input side of the start button to form a bypass loop, which is closed when the intermediate relay coil is energized, and the other normally closed contact is closed when the intermediate relay coil is de-energized and connected to the heater stop indicator light, which is connected to the input side of the start button; The control circuit includes a heater start indicator light, a thermal relay, and a fault indicator light. The heater start indicator light is connected to the output side of the stop button; the thermal relay is used to cut off the circuit and issue a fault indication when the heater is overheated, and a normally closed contact of the thermal relay is installed on the output side of the solid-state relay; a normally open contact of the thermal relay is installed to close after the heater is overheated and is connected to the fault indicator light, and the fault indicator light is connected to the input side of the start button.

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