CN212514378U - High-temperature humidity measuring device - Google Patents

Abstract

The utility model relates to a high temperature and humidity measuring device, which comprises a gas circuit unit and a circuit unit; the gas path unit comprises a gas filter, a Venturi tube, a pressure regulating valve and a humidity measuring pool, wherein the gas filter is connected with the contraction section of the Venturi tube, the pressure regulating valve is connected with the inlet section of the Venturi tube, the diffusion section of the Venturi tube is connected with the humidity measuring pool, a temperature sensor and a humidity sensor are arranged in the humidity measuring pool, and the gas filter and the Venturi tube are heated by heaters; the circuit unit comprises an oscillation circuit, an analog-to-digital conversion circuit and a processor, the temperature sensor is connected with the processor through the analog-to-digital conversion circuit, the humidity sensor is connected with the processor through the oscillation circuit, and the processor outputs signals after software compensation calculation according to preset calibration parameters. The high temperature and humidity measuring device provided in the technical scheme can effectively solve the problems that the existing high temperature and humidity measuring device is greatly influenced by the external environment and is not suitable for high temperature and corrosion working conditions.

Description

High-temperature humidity measuring device

Technical Field

The utility model relates to a high temperature humidity measures technical field, concretely relates to high temperature humidity measuring device.

Background

The precision of high-temperature humidity measurement is a difficult problem in the field of measurement, and currently, common humidity measurement technologies include a cold mirror method, a gravimetric method, a wet-dry-bulb method and an electronic method (such as a resistance method, a capacitance method and the like). The cold mirror method is characterized in that the temperature of a measuring air chamber is reduced to be below a humidity condensation point by cooling a lens semiconductor, and water mist is generated on the surface of a lens; the mirror reflection characteristic is measured through the light path, so that the humidity dew point value can be accurately obtained, and other humidity values can be obtained through conversion; the device can be conveniently used for high-temperature measurement, and has high precision; but only clean gases can be tested and corrosion and small amounts of dust can make the measurement inaccurate. The gravimetric method is to condense the humidity of the sample gas into liquid water by a cooling machine at high temperature, and the weight of the liquid water increased in unit time is the weight of the humidity increase; this method is often used in laboratories because of the high precision of weight in existing measurement techniques; the flow control in field measurement and the weight can be influenced by other factors, and the method is too expensive and complicated to limit. The dry-wet bulb method is that the relative humidity of the gas to be measured is obtained through the temperature curves of the dry bulb and the wet bulb; this method is less costly but very inaccurate; the corresponding factors such as flow rate, operation time and operators cannot be accurately controlled, and very large errors are easily caused. Electronic methods, most of the existing microelectronic sensor technologies are developed based on microelectronic materials such as glass, polymer, ceramic, silicon, etc., and are not suitable for high temperature and corrosion conditions. Therefore, it is necessary to design a new technical solution to comprehensively solve the problems in the prior art.

SUMMERY OF THE UTILITY MODEL

The utility model aims at providing a high temperature and humidity measuring device, it can effectively solve the problem that receives external environment influence big and be not suitable for high temperature and corruption operating mode that current high temperature and humidity measuring device exists.

In order to solve the technical problem, the utility model discloses a following technical scheme:

a high temperature and humidity measuring device comprises a gas circuit unit and a circuit unit;

the gas path unit comprises a gas filter, a venturi tube, a pressure regulating valve and a humidity measuring pool, the gas filter is connected with the contraction section of the venturi tube, the pressure regulating valve is connected with the inlet section of the venturi tube, the diffusion section of the venturi tube is connected with the humidity measuring pool, a temperature sensor and a humidity sensor are arranged in the humidity measuring pool, and the gas filter and the venturi tube are heated by a heater;

the circuit unit comprises an oscillation circuit, an analog-to-digital conversion circuit and a processor, the temperature sensor is connected with the processor through the analog-to-digital conversion circuit, the humidity sensor is connected with the processor through the oscillation circuit, and the processor outputs signals after software compensation calculation according to preset calibration parameters.

Wherein, the gas entering the gas filter is sample gas, and the gas entering the pressure regulating valve is instrument gas; the instrument gas is compressed air or high-purity nitrogen.

The humidity measurement formula is:

wherein, the humidity value measured by the mixed gas is the humidity value of the mixed gas of the sample gas and the instrument gas after passing through the Venturi tube.

Preferably, the temperature sensor is a platinum resistor.

According to the high-temperature humidity measuring device provided by the technical scheme, the sample gas enters the heated gas filter through the gas path inlet and then enters the Venturi tube heated by the heater; simultaneously instrument gas is through the air-vent valve pressure regulating, venturi after the heating produces the negative pressure, absorb the sample gas that gets into venturi, export gas humidity through venturi mixed gas reduces 50 ~ 100 times, humidity control is at 500 ~ 3000ppm, the gas that obtains after mixing is measured through temperature sensor and humidity transducer in the humidity measuring cell, temperature sensor passes through analog to digital conversion circuit connection treater, humidity transducer passes through oscillating circuit simultaneously and produces frequency signal, carry frequency signal for the treater, the treater is according to preset's calibration parameter, calculate through software compensation and obtain ultimate humidity value again.

The utility model discloses high temperature humidity measuring device utilizes gas mixing device to drop high temperature (more than 150 degrees) high humidity (0 ~ 40% v/v) gas humidity value to normal atmospheric temperature non-condensation state in proportion, need not to adopt the whole heating of traditional sample gas sampling method plus gas preliminary treatment, has reduced structural complexity, has avoided high temperature and corruption to cause the damage to equipment to greatly reduced the cost; the gas concentration is controlled by adopting a pressure regulating valve and a heater, so that the method is simple, convenient and convenient to control; in addition, the temperature sensor adopts a platinum resistor, and a mirror image constant current source is used for providing an excitation signal for the platinum resistor, so that the ambient temperature interference is eliminated; finally, through tests, the measurement precision of the high-temperature humidity measurement device can meet the reading value of 20% of relative error, and can basically meet most of the application of current online high-temperature humidity measurement.

Drawings

FIG. 1 is a system structure diagram of the high temperature and humidity measuring device of the present invention;

FIG. 2 is a circuit diagram of an analog-to-digital conversion circuit;

FIG. 3 is a circuit diagram of a mirror constant current source;

fig. 4 is a diagram of an oscillation circuit.

In the figure: 1. a gas path inlet; 2. a gas filter; 3. a heater; 4. a temperature sensor; 5. a circuit unit; 6. an evacuation interface; 7. a humidity sensor; 8. a humidity measuring cell; 9. a venturi tube; 10. a pressure regulating valve; 11. an instrument gas inlet.

Detailed Description

In order to make the objects and advantages of the present invention more apparent, the present invention will be described in detail with reference to the following embodiments. It is to be understood that the following text is only intended to describe one or several particular embodiments of the invention, and does not strictly limit the scope of the claims specifically claimed.

The technical scheme adopted by the utility model is as shown in figures 1-4, and the high temperature and humidity measuring device comprises a gas circuit unit and a circuit unit 5; the gas path unit comprises a gas filter 2, a Venturi tube 9, a pressure regulating valve 10 and a humidity measuring pool 8, sample gas enters the gas filter 2 from a gas path inlet 1 and then enters a contraction section of the Venturi tube 9 (specific proportion: 10-100), instrument gas (compressed air or high-purity nitrogen) passes through the pressure regulating valve 10 from an instrument gas inlet 11, mixed gas enters the humidity measuring pool 8 from an outlet of the Venturi tube 9 at an inlet section of the Venturi tube 9, an outlet pipeline of the humidity measuring pool 8 is connected with an emptying interface 6, a temperature sensor 4 (platinum resistor) and a humidity sensor 7 are arranged in the humidity measuring pool 8, and the gas filter 2 and the Venturi tube 9 are both processed by a heater 3 and kept above the dew condensation temperature of the sample gas; the temperature sensor 4 adopts a platinum resistor and provides a platinum resistor excitation signal by using a mirror image constant current source, thereby eliminating the ambient temperature interference.

The circuit unit 5 comprises an oscillation circuit, an analog-to-digital conversion circuit and a processor, the temperature sensor 4 is connected with the processor through the analog-to-digital conversion circuit, and the output voltage end V of the mirror image constant current source circuit is combined with the graph of fig. 2 and 3_outThe AD3 connected with the processor MCU acquires an output voltage end V_outThe voltage value of (1) is I ═ V_outThe current value I of the constant current source can be obtained by the Ra, and the platinum resistor PT is driven by the constant current source; the analog-digital conversion circuit converts a resistance value of the temperature sensor 4 changing along with the temperature into a measurable voltage signal, the processor MCU obtains an AD1 terminal voltage which is U1, and an AD2 terminal voltage which is U2, and the voltage value of the two ends of the temperature sensor 4 is U1-U2; and (3) carrying out data processing on the measured voltage signal, wherein the resistance value of the platinum resistor can be obtained by using U/I (U/I), and then looking up the table to obtain a high-precision temperature change value.

The humidity sensor 7 is connected with the processor through the oscillating circuit, with reference to fig. 4, after the power is switched on, VCC charges the humidity sensor C through R1 and R2, when the voltage Vc across the C rises to 2VCC/3, Vo outputs low level, at this time, C starts to discharge through R2 and chip IC1, when Vc drops to VCC/3, Vo outputs high level, VCC charges the humidity sensor C through R1 and R2, and the process is repeated in this way to form the oscillating circuit, generate the frequency signal Vo, and transmit the frequency signal Vo to the processor, and then the processor outputs the signal after software compensation calculation according to preset calibration parameters. The humidity sensor 7 can measure humidity in a normal temperature precision dominant section, and high precision temperature conversion is added to obtain a high precision value.

The humidity measurement formula is:

wherein, the humidity value measured by the mixed gas is the humidity value of the mixed gas of the sample gas and the instrument gas after passing through the Venturi tube.

In a word, the high temperature and humidity measuring device provided by the utility model adopts high purity nitrogen or compressed air to dilute the concentration of the sample gas by 50-100 times, utilizes the heater to reduce the humidity temperature below the normal temperature dew point, and then adopts the traditional humidity capacitance type measuring method to measure, thereby avoiding the damage of high temperature and corrosion to the equipment, and effectively prolonging the service life and the measuring accuracy of the equipment; meanwhile, through testing, the precision of the high-temperature humidity measuring device can meet the reading value of 20% relative error, and can basically meet most of the application of current on-line high-temperature humidity measurement.

The above detailed description of the embodiments of the present invention has been provided with reference to the accompanying drawings, but the present invention is not limited to the above embodiments, and those skilled in the art can make several equivalent transformations and substitutions without departing from the principles of the present invention after learning the contents of the present invention.

Claims (5)

1. A kind of high-temperature humidity measuring device, characterized by: comprises a gas circuit unit and a circuit unit;

the gas path unit comprises a gas filter, a venturi tube, a pressure regulating valve and a humidity measuring pool, the gas filter is connected with the contraction section of the venturi tube, the pressure regulating valve is connected with the inlet section of the venturi tube, the diffusion section of the venturi tube is connected with the humidity measuring pool, a temperature sensor and a humidity sensor are arranged in the humidity measuring pool, and the gas filter and the venturi tube are heated by a heater;

the circuit unit comprises an oscillation circuit, an analog-to-digital conversion circuit and a processor, the temperature sensor is connected with the processor through the analog-to-digital conversion circuit, the humidity sensor is connected with the processor through the oscillation circuit, and the processor outputs signals after software compensation calculation according to preset calibration parameters.

2. A high temperature humidity measurement device according to claim 1, wherein: the gas entering the gas filter is sample gas, and the gas entering the pressure regulating valve is instrument gas.

3. A humidity measurement device as claimed in claim 2, wherein: the instrument gas is compressed air or high-purity nitrogen.

4. A humidity measurement device according to claim 3, wherein the humidity is measured by the formula:

wherein, the humidity value measured by the mixed gas is the humidity value of the mixed gas of the sample gas and the instrument gas after passing through the Venturi tube.

5. A high temperature humidity measurement device according to claim 1, wherein: the temperature sensor is a platinum resistor.

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