CN114858858A - Automatic high accuracy frost point appearance of calibration - Google Patents

Abstract

The invention discloses an automatic-calibration high-precision frost point instrument, which comprises a high-precision frost point instrument body, wherein a thermoelectric refrigerator is arranged on the high-precision frost point instrument body, a signal transmitter is arranged in the center of the upper surface of the thermoelectric refrigerator, a temperature sensor is arranged in the center of the signal transmitter, a mirror surface is arranged above the temperature sensor in the horizontal direction, a signal receiver is arranged on the upper surface of the mirror surface, a dew point measuring chamber is arranged above the thermoelectric refrigerator, an air inlet port and an air outlet port are respectively arranged on two sides of the dew point measuring chamber, and an image analysis device is arranged in the center of the top of the dew point measuring chamber.

Description

A high-precision frost point meter with automatic calibration

technical field

The invention relates to the technical field of frost point instruments, in particular to an automatic calibration high-precision frost point instrument.

Background technique

Air humidity is a very important parameter in industrial production and storage. Precision dew point meter is a common humidity measurement and testing equipment, which is mainly used in gas preparation, drying industry, meteorology, food industry and other fields. In recent years, the research of humidity control has received more and more attention. Therefore, the accurate and reliable value of the precision dew point meter is of great significance to ensure agricultural and industrial production.

At present, some precision dew point meters have the problem of confusion between frost point and dew point calculation relative humidity. Therefore, this technical solution provides an automatic calibration high precision frost point meter to solve this problem in the prior art.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a high-precision frost point meter that can measure relative humidity and correct dew point temperature under different pressures, with high calculation accuracy and fast detection speed. .

In order to achieve the above purpose, the present invention provides the following technical solutions: an automatic calibration high-precision frost point meter, comprising a high-precision frost point meter body, the bottom of the high-precision frost point meter body is provided with a thermoelectric refrigerator, and the thermoelectric refrigerator A temperature sensor is arranged in the upper center of the temperature sensor, a mirror surface is arranged on the outside of the temperature sensor, and a mirror surface is arranged on the top of the mirror surface housing. device, signal receiver;

A dew point measurement chamber is arranged on the upper and outer sides of the thermoelectric refrigerator, and the dew point measurement chamber is fixedly connected with the thermoelectric refrigerator.

Preferably, an image analysis device is provided in the center of the inner top of the dew point measurement chamber, an air inlet port is provided on the left side wall of the dew point measurement chamber, and an air outlet port is provided on the right side wall of the dew point measurement chamber. The inlet port and the outlet port are arranged at the same level.

Preferably, when the high-precision frost point instrument body is used as a relative humidity standard, if its relative humidity display value is directly used, the displayed value should be no more than the relative humidity value calculated from the dew point and temperature values collected by the instrument. ±0.1%.

Preferably, the ambient temperature of the high-precision frost point meter body should be between 15°C and 30°C and relatively constant, and the ambient temperature of the dew point measurement chamber and the sampling pipeline system is higher than the gas to be measured. When the dew/frost point temperature is above 5℃, when the dew point temperature during measurement is higher than the ambient temperature, all the measuring pipelines are in the heating state, so that the pipeline temperature is 5℃～10℃ higher than the dew point temperature.

Preferably, a measurement standard is provided on the body of the high-precision frost point instrument, and the measurement standard includes a primary measurement standard and a secondary measurement standard;

The dew point measurement range of the reference humidity generator on the first-level measurement standard is D.06+～0.06-, the technical requirements of the reference humidity generator dew point: U/MPEV≤1/3

The measurement range of the gravimetric hygrometer is -30°C to +25°C, and the mixing ratio range of the gravimetric hygrometer is Um≤0.31%;

The dew point measurement range of the upper-level standard humidity generator of the second-level metering standard is -90℃～+90℃, and the first-level or dew point range is U/MPEV≤1/3;

The dew point measurement range of the first-level precision dew point meter on the second-level measurement standard is 0.06+～0.06-, and the first-level or dew point range is U/MPEV≤1/3.

Preferably, the dew point generation range of the humidity generator of the first-level measurement standard on the body of the high-precision frost point instrument is -90°C to +90°C, and the dew point fluctuation of the humidity generator does not exceed ±0.05°C/30min;

The dew point generation range of the humidity generator of the secondary metering standard is -90℃～+90℃, and the dew point fluctuation of the humidity generator does not exceed ±0.10℃/30min.

Preferably, the body of the high-precision frost point meter takes the average value of each verification point, and the difference between the average value of the displayed value of the tested dew point meter and the average value of the standard device is called the displayed value error of the tested dew point meter, according to the formula (1) calculation;

ΔT _d =T _d -T' _d (1)

In the formula: ΔT _d is the indication error of the dew point meter to be inspected, °C;

T _d is the average value of the dew point meter to be inspected, ℃;

T' _d is the average dew point of the standard device, °C;

For each verification point, the dew point indication value T1 recorded by the dew point meter to be inspected for 6 times is recorded, and the experimental standard deviation of the indication value is calculated according to formula (2) as its repeatability.

In the formula: S is the experimental standard deviation of the indicated value, ℃;

T _d is the average value of the dew point meter to be inspected, ℃;

n is the number of repeated measurements, where n=6.

Preferably, the relative humidity is defined according to the definition of relative humidity when the high-precision frost point meter body performs the calculation of the relative humidity measurement, and the relative humidity of the dew point meter can be calculated according to the formula:

where:

H _s - is the relative humidity of the measured gas;

f- is the value-added coefficient of the measured gas, which is a function of the temperature and pressure of the measured gas;

T _d - is the dew point temperature of the measured gas, °C;

T _s - is the temperature of the gas to be measured, °C;

P- is the measured gas pressure, Pa;

_{es (T d )} is the dew point temperature T. Corresponding pure water or ice plane saturated water vapor pressure, Pa;

_{es (T s )} is the temperature T, corresponding to the saturated water vapor pressure of the pure water plane or ice plane, Pa.

Preferably, under the condition that the high-precision frost point meter body does not undergo phase change, the moisture changes from the pressure p' state to the pressure p state, and the dew point changes from T' to Ta, and the dew point under different pressures can be determined according to the formula (B .1) Calculate:

In the formula: f - the value-added coefficient of the measured gas, which is a function of the temperature and pressure of the measured gas;

T _d - the dew point temperature of the gas to be measured under the state of pressure p, °C;

T' _d - the dew point temperature of the gas to be measured under the state of pressure p', °C;

p - final pressure of the gas to be measured, Pa;

p'-initial pressure of the gas to be measured, Pa;

_{es (T d )} - dew point temperature T. Corresponding pure water or ice plane saturated water vapor pressure, Pa;

_{es (T' d )} - dew point temperature T. Corresponding pure water or ice plane saturated water vapor pressure, Pa.

By measuring the initial pressure of the measured gas, the final pressure and the initial dew point of the measured gas, the value of _{es (T d )} can be obtained from the formula (B.1), and the final pressure p can be obtained by checking the saturated water vapor pressure gauge. Dew point value T.

Preferably, a measurement method for an automatically calibrated high-precision frost point meter comprises the following steps:

Step 1. The sample gas with the set dew point temperature is generated by the humidity generator, divided into several strands and connected to the dew point temperature sensor of the precision dew point meter, and the temperature of the constant temperature tank is 20.00 ℃;

Step 2. Both the temperature sensor of the precision dew point meter and the standard platinum resistance thermometer are inserted into the constant temperature bath;

Step 3: After the humidity generator and the constant temperature tank are stable, read the frost/dew point temperature indication, temperature indication and relative humidity value of the standard precision dew point meter and the tested precision dew point meter respectively.

Compared with the prior art, the beneficial effects of the present invention are:

(1) When the dew point meter has the relative humidity display function, in addition to the dew point indication error verification, it is also necessary to place the temperature probe of the dew point meter in a constant temperature environment, and record the dew point temperature, ambient temperature and relative humidity of the dew point meter respectively. value, and calculate the relative humidity value, the difference between the relative humidity display value of the dew point meter and the calculated value should not exceed ± 0.1%, which greatly improves the detection accuracy;

(2) The high-precision frost point meter can measure relative humidity and correct dew point temperature under different pressures, with high calculation accuracy and fast detection speed.

Description of drawings

FIG. 1 is a schematic diagram of the body structure of the high-precision frost point meter of the present invention.

In the figure: 1. High-precision frost point instrument body; 2. Inlet port; 3. Outlet port; 4. Platinum resistance temperature sensor; 5. Thermoelectric cooler; 6. Signal transmitter; 7. Signal receiver; 8. Image analysis device; 9. Dew point measurement chamber; 10. Mirror surface.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

Referring to FIG. 1, the present invention provides a technical solution: an automatic calibration high-precision frost point meter, comprising a high-precision frost point meter body 1, a thermoelectric refrigerator 5 is arranged at the bottom of the high-precision frost point meter body 1, and a thermoelectric A temperature sensor 4 is provided in the upper center of the refrigerator 5, a mirror surface is provided on the outside of the temperature sensor 4, and a mirror surface 10 is provided on the top of the mirror surface housing. Signal transmitter 6, signal receiver 7.

A dew point measurement chamber 9 is provided above and outside the thermoelectric refrigerator 5 , and the dew point measurement chamber 9 is fixedly connected to the thermoelectric refrigerator 5 .

The image analysis device 8 is arranged in the center of the inner top of the dew point measurement chamber 9, the air inlet port 2 is arranged on the left side wall of the dew point measurement chamber 9, the air outlet port 3 is arranged on the right side wall of the dew point measurement chamber 9, and the inlet port 2. The air outlet 3 is set at the same level.

When the high-precision frost point meter body 1 is used as a relative humidity standard, if its relative humidity display value is used directly, the displayed value should be within ±0.1% of the relative humidity value calculated from the dew point and temperature values collected by the instrument.

The ambient temperature of the high-precision frost point meter body 1 should be between 15°C and 30°C, and it should be relatively constant. The ambient temperature where the dew point measurement chamber 9 and the sampling pipeline system are located is higher than the dew/frost point of the gas to be measured. When the temperature is above 5°C, and the dew point temperature during measurement is higher than the ambient temperature, all measurement pipelines are in a heated state, so that the pipeline temperature is 5°C to 10°C higher than the dew point temperature.

The main body 1 of the high-precision frost point meter is provided with a measurement standard. The measurement standard includes a primary measurement standard and a secondary measurement standard. The dew point measurement range on the reference humidity generator on the primary measurement standard is D.06+～ 0.06-, the technical requirements of the reference humidity generator Dew point: U/MPEV≤1/3

The measurement range of the gravimetric hygrometer is -30°C to +25°C, and the mixing ratio range of the gravimetric hygrometer is Um≤0.31%.

The dew point measurement range of the upper-level standard humidity generator of the second-level measurement standard is -90℃～+90℃, the first-level or dew point range is U/MPEV≤1/3, and the upper-level precision dew point meter of the second-level metering standard The measurement range of the dew point is 0.06+～0.06-, and the first-level or dew point range is U/MPEV≤1/3.

Table 2 Technical requirements for measurement standards

The dew point range of the humidity generator of the upper-level measurement standard of the high-precision frost point meter body 1 is -90℃～+90℃, and the dew point fluctuation of the humidity generator does not exceed ±0.05℃/30min. The dew point generation range of the humidity generator is -90℃～+90℃, and the dew point fluctuation of the humidity generator does not exceed ±0.10℃/30min.

Technical requirements for humidity generators

The high-precision frost point meter body 1 takes the average value of each verification point, and the difference between the average value of the dew point meter under inspection and the average value of the standard device is called the display value error of the dew point meter under inspection, and it is calculated according to formula 1;

ΔT _d =T _d -T' _d

In the formula: ΔT _d is the indication error of the dew point meter to be inspected, °C;

T _d is the average value of the dew point meter to be inspected, ℃;

T' _d is the average dew point of the standard device, °C;

For each verification point, the dew point indication value T1 recorded by the dew point meter to be inspected for 6 times is recorded, and the experimental standard deviation of the indication value is calculated according to formula (2) as its repeatability.

In the formula: S is the experimental standard deviation of the indicated value, ℃;

T _d is the average value of the dew point meter to be inspected, ℃;

n is the number of repeated measurements, where n=6.

When the high-precision frost point meter body (1) calculates the relative humidity measurement, according to the definition of relative humidity, the relative humidity of the dew point meter can be calculated according to the formula:

where:

H _s - is the relative humidity of the measured gas;

f- is the value-added coefficient of the measured gas, which is a function of the temperature and pressure of the measured gas;

T _d - is the dew point temperature of the measured gas, °C;

T _s - is the temperature of the gas to be measured, °C;

P- is the measured gas pressure, Pa;

_{es (T d )} is the dew point temperature T. Corresponding pure water or ice plane saturated water vapor pressure, Pa;

_{es (T s )} is the temperature T, corresponding to the saturated water vapor pressure of the pure water plane or ice plane, Pa.

When the dew point meter has the relative humidity display function, in addition to the dew point indication error verification, it is also necessary to place the temperature probe of the dew point meter in a constant temperature environment to record the dew point temperature, ambient temperature and relative humidity indication value of the dew point meter respectively. And calculate the relative humidity value, the difference between the relative humidity display value of the dew point meter and the calculated value should not exceed ± 0.1%.

Under the condition of no phase change, the humidity of the high-precision frost point meter body 1 changes from the pressure p' state to the pressure p state, and the dew point changes from T' to Ta. The dew point under different pressures can be calculated according to formula (B.1) :

In the formula: f - the value-added coefficient of the measured gas, which is a function of the temperature and pressure of the measured gas;

T _d - the dew point temperature of the gas to be measured under the state of pressure p, °C;

T' _d - the dew point temperature of the gas to be measured under the state of pressure p', °C;

p - final pressure of the gas to be measured, Pa;

p' - initial state pressure of the gas to be measured, Pa;

_{es (T d )} - dew point temperature T. Corresponding pure water or ice plane saturated water vapor pressure, Pa;

_{es (T' d )} - dew point temperature T. Corresponding pure water or ice plane saturated water vapor pressure, Pa. By measuring the initial pressure of the measured gas, the final pressure and the initial dew point of the measured gas, the value of _{es (T d )} can be obtained from the formula (B.1), and the final pressure p can be obtained by checking the saturated water vapor pressure gauge. Dew point value T.

The measurement method of the automatic calibration high-precision frost point meter: the sample gas with the set dew point temperature is generated by the humidity generator, divided into several strands and connected to the dew point temperature sensor of the precision dew point meter, and the temperature of the constant temperature tank is 20.00 ℃.

The temperature sensor of the precision dew point meter and the standard platinum resistance thermometer are inserted into the constant temperature bath. After the humidity generator and the constant temperature bath are stable, read the frost/dew point temperature indication and the temperature indication of the standard precision dew point meter and the tested precision dew point meter respectively. and relative humidity values.

The high-precision frost point meter can measure relative humidity and correct dew point temperature under different pressures, with high calculation accuracy and fast detection speed.

Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, and substitutions can be made in these embodiments without departing from the principle and spirit of the invention and modifications, the scope of the present invention is defined by the appended claims and their equivalents.

Claims (10)

1. The utility model provides an automatic high accuracy frost point appearance of calibration, includes high accuracy frost point appearance body (1), its characterized in that: the high-precision frost point instrument comprises a high-precision frost point instrument body (1), wherein a thermoelectric refrigerator (5) is arranged at the bottom of the high-precision frost point instrument body (1), a temperature sensor (4) is arranged in the center above the thermoelectric refrigerator (5), a mirror surface shell is arranged outside the temperature sensor (4), a mirror surface (10) is arranged at the top of the mirror surface shell, the mirror surface (10) and the mirror surface shell are of an integral structure, and a signal transmitter (6) and a signal receiver (7) are arranged on the upper surface of the mirror surface (10);

and a dew point measuring chamber (9) is arranged on the outer side above the thermoelectric refrigerator (5), and the dew point measuring chamber (9) is fixedly connected with the thermoelectric refrigerator (5).

2. The self-calibrating high precision frost point gauge of claim 1, wherein: the dew point measuring chamber is characterized in that an image analysis device (8) is arranged in the center of the top of the inner side of the dew point measuring chamber (9), an air inlet port (2) is arranged on the side wall of the left side of the dew point measuring chamber (9), an air outlet port (3) is arranged on the side wall of the right side of the dew point measuring chamber (9), and the air inlet port (2) and the air outlet port (3) are arranged at the same horizontal height.

3. The self-calibrating high precision frost point gauge of claim 1, wherein: when the high-precision frost point instrument body (1) is used as a relative humidity standard instrument, if the relative humidity display value is directly used, the difference between the display value and the relative humidity value obtained by calculating the dew point and temperature value collected by the instrument is not more than +/-0.1%.

4. The self-calibrating high precision frost point gauge of claim 1, wherein: the environment temperature of the high-precision frost point instrument body (1) is 15-30 ℃ during measurement and is relatively constant, the environment temperature of the dew point measuring chamber (9) and the sampling pipeline system is higher than the dew/frost point temperature of the gas to be measured by more than 5 ℃, and when the dew point temperature during measurement is higher than the environment temperature, all measuring pipelines are in a heating state, so that the pipeline temperature is 5-10 ℃ higher than the dew point temperature.

5. The self-calibrating high precision frost point gauge of claim 1, wherein: the high-precision frost point instrument body (1) is provided with a measurement standard device, and the measurement standard device comprises a first-stage measurement standard device and a second-stage measurement standard device;

the measuring range of the upper dew point of the reference humidity generator on the first-level measuring standard device is D.06+ to 0.06-, and the technical requirement dew point of the reference humidity generator is as follows: U/MPEV is less than or equal to 1/3

The measurement range of the gravimetric hygrometer is-30 ℃ to +25 ℃, and the mixing ratio range of the gravimetric hygrometer is Um and is less than or equal to 0.31 percent;

the dew point measuring range of the first-stage standard humidity generator on the second-stage measuring standard device is between 90 ℃ below zero and 90 ℃, and the dew point range of the first-stage standard humidity generator or the first-stage standard humidity generator is U/MPEV which is not more than 1/3;

the dew point measuring range of the first-level precision dew point instrument on the second-level measuring standard instrument is 0.06 plus-0.06-, and the first-level or dew point range is U/MPEV which is less than or equal to 1/3.

6. The self-calibrating high precision frost point gauge of claim 1, wherein: the dew point generating range of a humidity generator of a first-stage metering standard device on the high-precision frost point instrument body (1) is-90 ℃ to +90 ℃, and the dew point fluctuation degree of the humidity generator does not exceed 0.05 ℃/30 min;

the dew point generating range of the humidity generator of the secondary metering standard device is-90 ℃ to +90 ℃, and the dew point fluctuation degree of the humidity generator does not exceed 0.10 ℃/30 min.

7. The self-calibrating high precision frost point gauge of claim 1, wherein: the high-precision frost point instrument body (1) takes an average value of each verification point, the difference between the indication average value of the detected dew point instrument and the standard average value is called the indication error of the detected dew point instrument, and the calculation is carried out according to the formula (1);

ΔT _d ＝T _d -T′ _d

in the formula: delta T _d The indication error of the dew point instrument to be detected is DEG C;

T _d the average value of the indication values of the dew point instrument to be detected is DEG C;

T′ _d is the standard dew point average, DEG C;

for each detection point, the dew point indication T1 of the detected dew point instrument is recorded for 6 times, and the experimental standard deviation of the indication is calculated according to the formula (2) as the repeatability.

In the formula: s is the experimental standard deviation of the indicated value, DEG C;

T _d the average value of the indication values of the dew point instrument to be detected is DEG C;

n is the number of repeated measurements, where n is 6.

8. The self-calibrating high precision frost point gauge of claim 1, wherein: the high-precision frost point instrument body (1) is defined according to relative humidity when calculating relative humidity measurement, and the relative humidity of a dew point instrument can be expressed as follows:

in the formula:

H _s -is the relative humidity of the gas being measured;

f-is the measured gas value increasing coefficient which is a function of the temperature and the pressure of the measured gas;

T _d -is the measured gas dew point temperature, deg.c;

T _s -is the measured gas temperature, deg.c;

p-is the measured gas pressure, Pa;

e _s (T _d ) Is the dew point temperature T. The corresponding pure water plane or ice plane saturated water vapor pressure, Pa;

e _s (T _s ) The corresponding pure water plane or ice plane is saturated with water vapor pressure, Pa, at temperature T.

9. The self-calibrating high precision frost point gauge of claim 1, wherein: under the condition that the high-precision frost point instrument body (1) does not generate phase change, moisture is changed from a pressure p 'state to a pressure p state, a dew point is changed from T' to Ta, and the dew points under different pressures can be calculated according to a formula (B.1):

in the formula: f-measured gas value increasing coefficient which is a function of the temperature and the pressure of the measured gas;

T _d -measured gas dew point temperature in pressure p, ° c;

T′ _d -measured gas dew point temperature, deg.c, at pressure p';

p-measured gas final state pressure, Pa;

p' -the measured gas initial pressure, Pa;

e _s (T _d ) Dew point temperature T. The corresponding pure water plane or ice plane saturated water vapor pressure, Pa;

e _s (T′ _d ) -dew point temperature T. The corresponding pure water plane or ice plane has saturated water vapor pressure, Pa.

By measuring the initial pressure, the final pressure and the initial dew point of the measured gas, e can be obtained from the formula (B.1) _s (T _d ) And checking a saturated water vapor pressure gauge to obtain a dew point value T under the state of final pressure p.

10. The measurement method for realizing the automatic calibration high-precision frost point instrument in the claim 1 comprises the following steps:

step one, generating sample gas with set dew point temperature by a humidity generator, wherein the sample gas is divided into a plurality of strands and is respectively connected to a dew point temperature sensor of a precision dew point instrument, and the temperature of a thermostatic bath is 20.00 ℃;

step two, inserting a temperature sensor of the precise dew point instrument and a standard platinum resistance thermometer into a constant temperature bath;

and step three, after the humidity generator and the constant temperature bath are stable, respectively reading a frost/dew point temperature indication value, a temperature indication value and a relative humidity value of the standard precision dew point instrument and the detected precision dew point instrument.

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