A high temperature flue gas humidity sensor

Abstract

The present invention discloses a high-temperature flue gas humidity meter sensor, which belongs to the technical field of flue gas humidity measurement. Aiming at the problem that the high-temperature flue gas humidity meter in the prior art corrodes and pollutes the sensor during measurement, thereby causing the humidity meter to have a short service life and a high failure rate, the present invention provides a high-temperature flue gas humidity meter sensor including a sensor base, a humidity sensitive element, a heating element, a temperature sensing element and a dustproof filter cover, wherein the dustproof filter cover is covered on the sensor base to form a volume of 2cm 3 Up to 7cm 3 The measuring space between the dust filter cover and the humidity sensor, heating element and temperature sensor are all arranged on the sensor base. The heating element is used to make the measuring space reach the protection condition. Direct and real-time protection is provided from the inside, which can reduce the influence of high dew point acidic substances on the sensor and extend the service life of the flue gas humidity meter.

Description

Technical Field

[0001] The invention relates to the technical field of flue gas humidity measurement, and more specifically to a high-temperature flue gas humidity meter sensor. Background Art

[0002] High-temperature flue gas generally refers to the waste gas generated by fixed pollution sources such as coal-fired power generation projects in the thermal power industry. It is a mixture of gas and smoke, and the gas temperature range is usually 60~180 degrees. High-temperature flue gas usually contains acidic gases such as sulfur dioxide, sulfur trioxide, nitrogen oxides, water vapor, oxygen, carbon monoxide and other gases and smoke, and the composition is very complex. How to overcome the pollution of dust on the sensor of the high-temperature flue gas humidity meter using the RC method (hereinafter referred to as the humidity meter sensor), overcome the corrosion of acidic substances on the sensor of the high-temperature flue gas humidity meter using the RC method, ensure the long-term online measurement of flue gas moisture, and improve the service life of the high-temperature flue gas humidity meter using the RC method (hereinafter referred to as the flue gas humidity meter) is a difficult problem. If moisture is measured under this condition for a long time, the humidity meter sensor will be corroded and damaged by pollution.

[0003] At present, the smoke humidity is generally measured by using a resistance-capacitance hygrometer, such as the patent application with application number ZL200520075144.X, an online resistance-capacitance high-temperature smoke moisture meter, which ensures the accuracy and reliability of smoke moisture measurement through smoke compensation technology. The existing technology hygrometer manufacturers generally extend the service life of the hygrometer by adding a protective device to the periphery of the hygrometer sensor, which is an indirect protection method. The main defect of this method is that the protection lag is obvious. The consequence of the protection lag is that the hygrometer sensor is corroded and contaminated, which directly leads to inaccurate and unstable humidity measurement, and ultimately leads to a short service life and high failure rate of the smoke humidity meter, which cannot meet the needs of long-term online measurement of high-temperature smoke humidity, and does not completely solve the stability problem of long-term online measurement of humidity in a high-temperature smoke environment.

[0004] With the requirement in the Technical Requirements and Detection Methods for Continuous Monitoring Systems of Flue Gas Emissions from Fixed Pollution Sources (SO2, NOx, Particulate Matter) HJ76-2017 that flue gas humidity be used as a flue gas parameter monitoring measurement unit and directly participate in the calculation of total emissions, the power and non-power industries will gradually impose strict requirements on humidity measurement. At present, the working conditions of many non-power industries are more complicated than those of the power industry, and the requirements for flue gas humidity meters are higher. Therefore, it is imperative to ensure that the flue gas humidity meter can measure online for a long time and measure stably and accurately. Summary of the invention

[0005] 1. Technical issues to be solved

[0006] In view of the problem in the prior art that high-temperature flue gas humidity meters corrode and contaminate sensors during measurement, which results in a short service life and a high failure rate of the humidity meter, the present invention provides a high-temperature flue gas humidity meter sensor, which can reduce the influence of high dew point acidic substances on the sensor and extend the service life of the flue gas humidity meter.

[0007] 2. Technical solution

[0008] The purpose of the present invention is achieved through the following technical solutions.

[0009] A high-temperature flue gas humidity meter sensor comprises a sensor base, a humidity-sensitive element, a heating element, a temperature-sensing element and a dust-proof filter cover, wherein the dust-proof filter cover is covered on the sensor base to form a measuring space; inside the dust-proof filter cover, the humidity-sensitive element, the heating element and the temperature-sensing element are all arranged on the sensor base, and the humidity-sensitive element and the temperature-sensing element are arranged on both sides of the heating element; a connecting piece is arranged on the sensor base, one end of the connecting piece is respectively connected to the humidity-sensitive element, the heating element or the temperature-sensing element, and the other end of the connecting piece is connected to the circuit of the high-temperature flue gas humidity meter.

[0010] The sensor of the high-temperature flue gas humidity sensor described in the present invention, the dust-proof filter cover forms a tiny measuring space on the sensor base, the sensor base is provided with a humidity-sensitive element, a heating element and a temperature-sensing element, the humidity-sensitive element and the temperature-sensing element are arranged on both sides of the heating element, the heating element is connected to the circuit through a connector, the circuit controls the heating of the heating element, so that the measuring space is quickly heated up to reach the protection condition of the sensor element, thereby improving the service life of the sensor, and can be used even under harsh working conditions.

[0011] Furthermore, the humidity sensitive element is connected to the heating element. The measuring space formed by the dustproof filter cover and the sensor base of the present invention is very small. The humidity sensitive element and the heating element are connected by high-temperature adhesive, which can further reduce the volume of the measuring space and enable the measuring space to quickly reach the protection conditions required to resist high dew point acidic substances.

[0012] Furthermore, the temperature sensing element is connected to the heating element. The temperature sensing element and the heating element are connected by high-temperature adhesive, which further reduces the volume of the measurement space. Compared with the humidity-sensitive element, the temperature sensing element is less affected by the corrosion of acidic substances. In a measurement environment with higher requirements, the temperature sensing element and the heating element are connected by high-temperature adhesive, so that the measurement space formed by the dustproof filter cover is smaller, the heating element responds faster, and the sensor is better protected.

[0013] Furthermore, the volume of the measuring space is between 2cm3 and 7cm3. According to the different settings of the humidity-sensitive element, the heating element and the temperature-sensitive element, the volume of the measuring space is between 2cm3 and 7cm3, which is much smaller than the sensor measuring space in the prior art. After heating, the protective condition can be quickly reached, thereby extending the service life of the sensor.

[0014] Furthermore, when the heating element is connected to the humidity-sensitive element or the temperature-sensing element, the pins of the heating element, the humidity-sensitive element and the temperature-sensing element are bent. The heating element, the humidity-sensitive element and the temperature-sensing element are all set on the sensor base through pins. When the elements are connected by high-temperature adhesive, the pins need to be bent so that the elements fit closely.

[0015] Furthermore, the humidity-sensitive element, the heating element or the temperature-sensitive element is connected to the sensor base through a pair of connecting pieces.

[0016] Furthermore, the connecting piece is a metal wire, and the outer layer of the metal wire is gold-plated.

[0017] Furthermore, the circuit includes a heating circuit, a high-frequency oscillation circuit and a flue gas temperature compensation processing circuit; the heating circuit is connected to the heating element through a gold needle, the high-frequency oscillation circuit is connected to the humidity sensitive element through a gold needle, and the flue gas temperature compensation processing circuit is connected to the temperature sensing element through a gold needle.

[0018] Furthermore, the circuit also includes a frequency-voltage conversion circuit and a voltage-current conversion circuit, the humidity-sensitive element is connected to the input end of the high-frequency oscillation circuit, the output end of the high-frequency oscillation circuit is connected to the input end of the frequency-voltage conversion circuit, and the frequency-voltage conversion circuit is connected to the input end of the high-frequency oscillation circuit.

[0019] The output end of the conversion circuit and the temperature sensing element are commonly connected to the input end of the flue gas temperature compensation processing circuit, the output end of the flue gas temperature compensation processing circuit is connected to the input end of the voltage-current conversion circuit, and the input end of the voltage-current conversion circuit is connected to the display monitoring device of the high-temperature flue gas humidity meter.

[0020] Furthermore, the heating element is a sheet-type heating element, the humidity-sensitive element is a polymer film capacitor humidity-sensitive element, and the temperature-sensing element is a flue gas temperature sensor. The prior art heating elements mostly use parts such as heating wires or heating rods, which are not only large in size but also consume a lot of power, and the power is generally 30 to 50W. The present invention uses a sheet-type heating element, which is arranged in a tiny measuring space to quickly heat the tiny measuring space where the humidity-sensitive element is located to reach the dew point temperature required for protection. The power of the sheet-type heating element is generally 1 to 4W, which has a better protection effect under the premise of greatly reducing energy consumption. The humidity-sensitive element is used for flue gas moisture measurement. The temperature-sensing element is used for flue gas temperature sensing for temperature compensation.

[0021] Unlike the prior art in which the heating element is arranged outside the sensor, the present invention arranges the heating element inside the sensor base, in the same measuring space as the humidity-sensitive element and the temperature-sensing element, to better protect the sensor and extend its service life. The high-temperature flue gas humidity meter sensor of the present invention arranges a heating element on the sensor base, connects the heating element to the heating circuit through a connecting gold needle, and constructs a tiny measuring space through a dustproof filter cover on the outer layer of the heating element, the humidity-sensitive element and the temperature-sensing element. The heating circuit measures in real time through the gold needle. Since the measuring space has a small volume, the measuring space can quickly reach the protection conditions required to resist high dew point acidic substances after the heating element is heated, greatly increasing the service life of the high-temperature flue gas humidity meter sensor.

[0022] 3. Beneficial effects

[0023] Compared with the prior art, the advantages of the present invention are:

[0024] The present invention focuses on constructing a tiny measuring space inside the RC hygrometer sensor. Since the tiny measuring space is small enough, the protection conditions of the tiny measuring space can be achieved within tens of seconds, so the protection provided by the present invention is direct and real-time. The existing technologies all implement protection outside the RC hygrometer sensor. Since the space to be protected is much larger, the most direct disadvantage is that the protection lag is obvious. It usually takes tens of minutes or even hours to have a protective effect, or the protection conditions are not met in the end and the protection effect is not played. The existing technology cannot prevent the formation of high dew point acidic substances in high-temperature flue gas in real time, thereby generating strong corrosive substances to corrode and damage the core components of the RC hygrometer sensor, and even directly cause corrosion damage, resulting in a short service life of the RC hygrometer sensor. The service life of the hygrometer sensor of the existing technology under harsh working conditions is only a few days.

[0025] The sensor protection device of the prior art is arranged outside the sensor, which is large in size and consumes a lot of power. In order to obtain a better sensor protection effect, the prior art often requires continuous increase in power or long-term heating, which consumes a lot of energy. The heating element of the present invention is arranged in a tiny measuring space, and only a few watts of sheet heater is needed for real-time heating, thereby directly protecting the sensor. The present invention arranges the heating element on the sensor base. The present invention abandons the conventional method of continuously increasing the power of the heating element to obtain a better protection effect, and arranges the heating element on the sensor. The protection conditions can be met with very little power, and the sensor space does not need additional changes, which is a qualitative improvement in this field.

[0026] The present invention reconstructs the tiny measuring space in the high-temperature flue gas hygrometer sensor and the tiny measuring space condition protection circuit connected thereto, tracks the tiny measuring space protection condition in real time, can quickly make the tiny measuring space reach the required protection condition, prevent the formation of high dew point acidic substances in the high-temperature flue gas, avoid the problem of strong corrosion of the resistance-capacitance hygrometer sensor by acidic substances, and ensure that the humidity sensitive elements, temperature sensitive elements, etc. in the tiny measuring space are effectively protected at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic diagram of the structure of the sensor of the present invention; Figure 2 It is a schematic diagram of the sensor of the present invention;

[0028] Figure 3 This is a schematic diagram of the sensor connection of the present invention; Figure 4 It is the installation schematic diagram of the present invention;

[0029] Description of the numbers in the figure:

[0030] 1. Sensor base; 2. Humidity-sensitive element; 3. Heating element; 4. Temperature-sensing element; 5. Dust-proof filter cover; 6. Gold needle. DETAILED DESCRIPTION

[0031] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0032] Example 1

[0033] In the prior art, a protective device is added to the outside of the sensor in the high-temperature flue gas humidity meter, and the sensor is protected by an indirect and delayed protection method. In applications, it often takes dozens of minutes or even hours to achieve the protection effect. Different from the prior art, this embodiment reconstructs the tiny measurement space of the high-temperature flue gas humidity meter sensor, and enables the tiny measurement space to quickly reach the protection conditions required to resist high dew point acidic substances. By improving the internal structure of the sensor, the purpose of increasing the service life of the flue gas humidity meter sensor is achieved. The measurement space can reach the protection conditions within a few seconds at the fastest. Since the measurement air conditioner is small and the heating speed is fast, the sensor can be protected in real time.

[0034] The sensor of this embodiment includes a sensor base 1, a humidity sensitive element 2, a heating element 3 and a temperature sensing element 4. Figure 1As shown, the humidity-sensitive element 2, the heating element 3 and the temperature-sensing element 4 are all arranged on the sensor base 1, and the sensor base 1 is the carrier of the humidity-sensitive element 2, the temperature-sensing element 4 and the heating element 3; the humidity-sensitive element 2, the heating element 3 and the temperature-sensing element 4 are evenly arranged on the sensor base 1, and the heating element 3 is centrally arranged on the sensor base 1. There is no restriction on the positions of the humidity-sensitive element 2 and the temperature-sensing element 4, and they only need to be evenly arranged on both sides of the heating element 3.

[0035] The humidity sensor 2 is a polymer film capacitor humidity sensor, which is used for measuring the moisture content of flue gas; the temperature sensing element 4 is a flue gas temperature sensor, which is used for temperature compensation of flue gas temperature sensing; the heating element 3 is a micro-chip heating element, which is used for rapid heating. The heating element 3 heats the tiny measuring space where the polymer film capacitor humidity sensor 2 is located and reaches the dew point temperature required for protection. The present invention realizes real-time protection of the high-temperature flue gas humidity meter sensor by embedding the micro-chip heating element 3 on the sensor base through the structural setting.

[0036] like Figure 3 As shown, the sensor base 1 includes three pairs of small uniformly arranged through the upper and lower end surfaces of the sensor base 1.

[0037] The gold needle 6 penetrates the upper and lower end faces in the small holes. After the gold needle 6 is inserted, the three pairs of small holes are airtight. In this embodiment, the gold needle 6 is a connector connecting the component and the circuit, which is a metal wire with a gold-plated outer layer. Other connectors can also be used in actual applications.

[0038] The upper ends of the gold pins 6 are respectively welded to the humidity sensitive element 2, the heating element 3 and the temperature sensing element 4, and each element is connected to a pair of gold pins 6. Since the heating element 3 is arranged at the center of the sensor base 1, when the gold pins 6 are connected to the elements, the pair of gold pins 6 located in the middle of the sensor base 1 is connected to the micro-chip heating element 3, and the two pairs of gold pins 6 on the side of the sensor base 1 are respectively connected to the humidity sensitive element 2 and the temperature sensing element 4.

[0039] like Figure 2 As shown, the sensor further includes a dustproof filter cover 5, which is covered on the sensor base 1. The dustproof filter cover 5 contains a humidity sensitive element 2, a heating element 3 and a temperature sensing element 4. The gold needles 6 are evenly distributed on the sensor base 1. The humidity sensitive element 2, the heating element 3 and the temperature sensing element 4 are all connected to the gold needles 6 and are also evenly distributed on the sensor base 1. The dustproof filter cover 5 forms a small measuring space for the sensor to work. The volume of the small measuring space is 2 cm 3 Up to 7cm 3 between.

[0040] The high temperature flue gas humidity meter also includes a heating circuit, a high frequency oscillation circuit, a frequency voltage conversion circuit, a flue gas temperature compensation processing circuit and a voltage current conversion circuit. The sensor base 1 is assembled with the high temperature flue gas humidity meter through three pairs of gold pins 6 as shown in the figure. Figure 4 As shown. The heating circuit of the high-temperature flue gas humidity meter is connected to the heating element 3 through a gold needle, that is, the upper end of a pair of gold needles 6 located in the middle of the sensor base 1 is connected to the heating element 3, and the lower end of the pair of gold needles 6 is connected to the heating circuit. By real-time tracking of the protection conditions of the tiny measurement space, a signal is applied to the micro-chip heating element 3 through the heating circuit, so that the tiny measurement space quickly reaches the required protection dew point temperature, preventing the formation of conditions for the strong corrosion of the sensor by high dew point acidic substances, and greatly improving the service life of the resistance-capacitance method high-temperature flue gas humidity meter sensor. The upper ends of the other two pairs of gold needles 6 are connected to the humidity-sensitive element 2 and the temperature-sensitive element 4 respectively, the lower end of the gold needle 6 connected to the humidity-sensitive element 2 is connected to the high-frequency oscillation circuit, and the lower end of the gold needle 6 connected to the temperature-sensitive element 4 is connected to the flue gas temperature compensation circuit. When the sensor is working, the humidity sensitive element 2 is connected to the input end of the high-frequency oscillation circuit, the output end of the high-frequency oscillation circuit is connected to the input end of the frequency-voltage conversion circuit, the output end of the frequency-voltage conversion circuit outputs a voltage signal proportional to the moisture content, and is connected to the input end of the flue gas temperature compensation processing circuit together with the temperature sensing element 4. The signal after flue gas temperature compensation is sent to the voltage-current conversion circuit to generate a corresponding current signal, which is output to the display monitoring device of the humidity meter.

[0041] When the high-temperature flue gas humidity meter using the resistance-capacitance method of this embodiment is working, the tiny measuring space constructed by the high-temperature flue gas humidity meter sensor monitors the protection condition parameters in the tiny measuring space in real time through the tiny measuring space condition control circuit, and adjusts the working state of the micro-chip heating element 3 connected to the heating circuit, so that the heating element 3 is quickly heated to quickly reach the protection condition required by the tiny measuring space.

[0042] When measuring the humidity of high-temperature flue gas, the high-temperature flue gas diffuses into the tiny measuring space through the dustproof filter cover 5. At the same time, the dustproof filter cover 5 prevents the smoke in the flue gas from entering the tiny measuring space, thereby blocking the pollution of the humidity meter sensor by the smoke. The micro-chip heating element 3 is controlled by the tiny measuring space condition heating circuit connected to it to heat, adjust the working state of the micro-chip heating element 3 connected to it, and make the tiny measuring space reach the required protection conditions in a very short time, preventing the high dew point acidic substances in the high-temperature flue gas from forming strong corrosive conditions, so that all components in the tiny measuring space are quickly and effectively protected, playing a role of real-time protection, greatly improving the service life of the humidity meter sensor and the demand for long-term online stable measurement of flue gas humidity, and can even be used under more severe working conditions.

[0043] The RC method high temperature flue gas humidity meter sensor of this embodiment is provided with a gold pin 6 on the sensor base 1 to connect the heating element 3 and the heating circuit. The heating circuit controls the heating element 3 to heat up to the required protection condition of the sensor according to the real-time state of the tiny measurement space, thereby protecting the humidity meter sensor in real time and prolonging the service life of the high temperature flue gas humidity meter. The measurement space formed by the sensor in this embodiment is very small, with a volume of 2cm 3 Up to 7cm 3 The tiny measuring space is between one twentieth and one tenth of the conventional sensor measuring space. The tiny measuring space enables the heating element 3 to heat the sensor measuring space in a short time and with a fast response speed, thus providing a better protection effect on the sensor.

[0044] Example 2

[0045] This embodiment is basically the same as the embodiment 1, except that the polymer film capacitor humidity sensor 2 and the smoke temperature sensor 4 in this embodiment are attached to the two sides of the micro-chip heating element 3, rather than being spaced apart from the micro-chip heating element 3. The attachment refers to the connection between the humidity sensor 2 or the temperature sensor 4 and the heating element by high temperature glue, and since the component pins will affect the tightness of the attachment during the connection, the component pins are bent accordingly during the attachment.

[0046] Compared with the spaced arrangement of the humidity sensor 2 and the temperature sensor 4, the required sensor base 1 is smaller, the measurement space formed by the sensor base 1 and the dust filter cover 5 is also smaller, and the heating response speed of the heating element 3 is faster. However, since the humidity sensor 2 and the temperature sensor 4 are both arranged in close contact with the heating element 3, the processing technology of the high-temperature flue gas humidity meter sensor is more demanding.

[0047] Example 3

[0048] This embodiment is basically the same as the embodiment 1, except that the polymer film capacitor humidity sensor 2 in this embodiment is attached to one side of the micro-chip heating element 3, and there is no requirement for the position of the smoke temperature sensing element 4. The sensing element 4 can be spaced apart from the heating element 3 or attached to the heating element 3. The attachment method of the elements in this embodiment is consistent with that in the embodiment 2, and will not be described again.

[0049] Compared with the temperature sensing element 4, the humidity sensing element 2 is more affected by the high dew point acidic substances in the high temperature flue gas. The humidity sensing element 2 and the heating element 3 are arranged in a close relationship to increase the service life of the high temperature flue gas humidity meter, and the temperature sensing element 4 does not need to be in close relationship with the heating element 3. The measurement space of the sensor in this embodiment is larger than the sensor structure described in Example 2, but the manufacturing process is less difficult than the structure described in Example 2.

[0050] The above schematically describes the invention and its implementation methods, which is not restrictive. Without departing from the spirit or basic features of the invention, the invention can be implemented in other specific forms. What is shown in the accompanying drawings is only one of the implementation methods of the invention. The actual structure is not limited to this, and any figure mark in the claims should not limit the claims involved. Therefore, if a person of ordinary skill in the art is inspired by it, without departing from the purpose of the invention, a structural method and an embodiment similar to the technical solution are designed without creativity, which should all fall within the scope of protection of this patent. In addition, the word "including" does not exclude other elements or steps, and the word "one" before the element does not exclude the inclusion of "multiple" elements. The multiple elements stated in the product claim can also be implemented by one element through software or hardware. The words first, second, etc. are used to indicate names, and do not indicate any specific order.

Claims

1. A high temperature flue gas humidity meter sensor, characterized in that: The invention comprises a sensor base, a humidity sensitive element, a heating element, a temperature sensing element and a dustproof filter cover, wherein the dustproof filter cover is covered on the sensor base to form a measuring space; inside the dustproof filter cover, the humidity sensitive element, the heating element and the temperature sensing element are all arranged on the sensor base, and the humidity sensitive element and the temperature sensing element are arranged on both sides of the heating element; a connecting piece is arranged on the sensor base, one end of the connecting piece is respectively connected to the humidity sensitive element, the heating element or the temperature sensing element, and the other end of the connecting piece is connected to the circuit of the high-temperature flue gas humidity meter; the volume of the measuring space is 2cm 3 Up to 7cm 3 The heating element is a miniature chip heating element for rapid heating; the humidity-sensitive element is fitted with the heating element; the connecting piece is a metal wire, and the outer layer of the metal wire is gold-plated.

2. A high temperature flue gas humidity meter sensor according to claim 1, characterized in that: The temperature sensing element is connected to the heating element.

3. A high temperature flue gas humidity meter sensor according to claim 2, characterized in that: When the heating element is connected to the humidity-sensitive element or the temperature-sensing element, the pins of the heating element, the humidity-sensitive element and the temperature-sensing element are bent.

4. A high temperature flue gas humidity meter sensor according to claim 3, characterized in that: The humidity-sensitive element, the heating element or the temperature-sensitive element is connected to the sensor base through a pair of connecting pieces.

5. A high temperature flue gas humidity meter sensor according to claim 4, characterized in that: The circuit includes a heating circuit, a high-frequency oscillation circuit and a flue gas temperature compensation processing circuit; the heating circuit is connected to the heating element through a gold needle, the high-frequency oscillation circuit is connected to the humidity sensitive element through a gold needle, and the flue gas temperature compensation processing circuit is connected to the temperature sensing element through a gold needle.

6. A high temperature flue gas humidity meter sensor according to claim 5, characterized in that: The circuit also includes a frequency-voltage conversion circuit and a voltage-current conversion circuit. The humidity-sensitive element is connected to the input end of the high-frequency oscillation circuit, the output end of the high-frequency oscillation circuit is connected to the input end of the frequency-voltage conversion circuit, the output end of the frequency-voltage conversion circuit and the temperature-sensing element are commonly connected to the input end of the flue gas temperature compensation processing circuit, the output end of the flue gas temperature compensation processing circuit is connected to the input end of the voltage-current conversion circuit, and the input end of the voltage-current conversion circuit is connected to the display monitoring device of the high-temperature flue gas humidity meter.

7. The high temperature flue gas humidity meter sensor according to claim 1, characterized in that: The humidity sensitive element is a polymer film capacitor humidity sensitive element, and the temperature sensing element is a flue gas temperature sensor.

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