Condensation hygrometer

 

(57) Abstract:

The proposed condensation hygrometer relates to techniques for measuring the humidity of gases and can be used for measuring low dew point directly at high pressures. The measuring chamber of the hygrometer made in the form of multiple longitudinal symmetrical cylindrical channels, which is the condensing mirrors. One of the channels is equipped with an insert in the form of a hollow cylinder made of a material with lower thermal conductivity than the material of the measuring chamber. The cavity insert is connected with the output of the sample gas pipeline and manifold. The hygrometer is equipped with a cooler, a temperature sensor, a light source and a photodetector. Between the light source and the measuring chamber installed reflector. A sight glass is located coaxially with the measuring chamber. The technical result of the invention is to improve the measurement accuracy of the dew point and the reduction of the sample gas. 2 Il.

The invention relates to techniques for measuring the humidity of gases. Primary area of use is the measurement of low values of dew point directly at high pressures.

The disadvantage of this hygrometer is that a relatively large volume of the measuring chamber and a relatively small area of the condensing mirror lead to the fact that the great mass of the sample gas does not participate in the process of condensation flowing almost in the boundary layer, which leads to an increase in its consumption when measuring dew point. In addition, the temperature difference between the analyzed gas and condensing mirror increases with the lowering of temperature of the condensing mirror that leads to increased measurement errors.

Known condensation hygrometer containing the measuring chamber to the condensing mirror in the form of a cylindrical channel, the cooler, the light source, the photodetector and the temperature sensor (see, for example, [2]).

This hygrometer increased area of the condensing mirror. However, as the hygrometer discussed above, a large mass of the sample gas does not participate in the process of condensation of water vapor, and also has a substantial temperature difference between the analyzed gas and condensing mirror that is not rnost which is a measuring mirror, cooler, the light source, the photodetector and the temperature sensor (see, for example [3]) adopted for the prototype.

In the prototype reduced the number of analyzed gas not participating in the process of vapor condensation, but not resolved the issue of reducing the temperature difference between the analyzed gas and condensing mirror, resulting in large measurement errors.

In addition, all considered hygrometers excluded the possibility of visual observation of the surface of the condensing mirror.

The result of the invention is to improve the measurement accuracy of the dew point and reducing the number of analyzed gas needed for the measurements.

This result is achieved by the fact that in the proposed condensation hygrometer containing the measuring chamber to the condensing mirror in the form of a cylindrical channel, the cooler, the light source, the photodetector and the temperature sensor, the measuring chamber in the form of several longitudinal symmetrical channels, one of which is equipped with an insert in the form of a hollow cylinder made of a material with lower thermal conductivity than the material of the measuring chamber, the cavity of which is connected to the input of made reflector, and coaxially with the measuring tube is a sight glass.

The invention and its distinguishing features are that in the alleged condensation hygrometer measuring chamber in the form of several longitudinal symmetrical channels, one of which is equipped with an insert in the form of a hollow cylinder made of a material with lower thermal conductivity than the material of the measuring chamber. Between the light source and the measuring chamber installed reflector and coaxially with the measuring tube is a sight glass.

This results in a positive effect, consisting in the following. Rays from the light source, Bouncing, fall on all parts of the measuring mirrors, with a direct hit of light beams on the photodetector excluded. The presence of inserts of a material with lower thermal conductivity connecting the inlet pipe and header, allows you to pre-cool the gas, thereby decreasing the temperature difference between the analyzed gas and the surfaces of the channels of the measuring chamber.

Compared with the prototype of these channels (measuring mirrors) can be performed with much smaller diameters, as a result is that you can greatly reduce its consumption. In addition, the design provides for visual observation of the degree of purity of channels condensing mirrors to reveal the need of cleaning them. Compared with the prototype of the proposed condensation hygrometer relatively simple design.

Variant of practical implementation of the proposed condensation hygrometer shown in Fig. 1 and 2, which respectively depict the hygrometer in the cut and its cross section along a - A.

Condensation hygrometer includes measuring chamber 1, cases 2 and 3, the light source 4, a reflector 5, a protective glass 6 and 7, a sight glass 8, the inlet 9 and outlet 10 pipelines, box 11, collective screen 12, a sensor 13, the manifold 14, the insulating strips 15 and 16, the temperature sensor 17, the cooler 18.

The measuring chamber 1 is made of metal with high thermal conductivity (such as copper) with polished surfaces of the channels, the insert 11 and the inlet pipe 9 made of a metal with a relatively low thermal conductivity (e.g., stainless steel), the reflector 5 is made of metal (e.g. stainless steel) with a polished surface, for the manufacture of teplota is the quality of the light source 4 can be a source of infrared radiation, collectively, the screen 12 is a metal cone with a polished inner surface, the hole is set to the photodetector 13 (for example, photodiode), the cooler 18 is, for example, a thermopile, and a temperature sensor 17 is a thermistor.

Condensation hygrometer works as follows.

Analyzed the high-pressure gas through the inlet pipe 9 connected tangentially (not shown) with the cavity of the insert 11, enters the collector 14, where uniformly passes through the longitudinal channels of the measuring chamber 1, and then flows into the cavity between the protective glass 6 and through an outlet pipe 10 is discharged into the atmosphere. Simultaneously the cooler 18, the light source 4, the photodiode 13 and the temperature sensor 17. Due to significant differences of coefficients of thermal conductivity of the material of the measuring chamber 1 and the insert 11, will take place a certain temperature difference, automatically supported in the process. The temperature of the insert 11 is not reduced until the temperature of the gas dew point. The light rays from the light source 4 enters the reflector 5 and is directed in the longitudinal channels of the measuring chamber 1 through stvie providing coverage of all surfaces of the channels, to reduce measurement error. In Fig. 1 shows the course of the rays from the light source 4 to the photodetector 13 in one of the channels.

In addition, the use of an infrared light source, the rays of which intensively absorbed by the condensed phase of water vapor, also reduces the measurement error. In the absence of the condensed phase on the inner surfaces of the channels of the measuring chamber 1, the signal on the photodetector 13 is maximum. During the formation of the condensed phase the intensity of the light rays falling on the photodetector 13, sharply decreases due to the absorption of light condensed phase. Defined in this moment the temperature of the measuring chamber 1 temperature sensor 17 is the dew point of the gas.

Visual monitoring of the condition of the surfaces of the channels is carried out through a sight glass 8 to reveal the need of cleaning them.

Thus, the proposed condensation hygrometer compared with the prototype allows to reduce the amount of the sample gas, to automatically maintain the temperature difference between the analyzed gas and measuring channels, and substantially lowered the 397830, CL G 01 N 25/66, 1973.

2. Auth.St. USSR N 488126, CL G 01 N 25/66, 1975.

3. Auth.St. USSR N 1681218, CL G 01 N 25/66, 1991.

Condensation hygrometer containing a measuring chamber with a condensing mirror, the cooler, the light source, the photodetector and the temperature sensor, wherein the measuring chamber in the form of several longitudinal symmetrical cylindrical channels, one of which is provided with an insert in the form of a hollow cylinder made of a material with lower thermal conductivity than the material of the measuring chamber, the cavity of which is connected to the input of the sample gas pipeline and collector, and the rest are channels condensing mirrors, between the light source and the measuring chamber installed reflector and coaxially with the measuring tube is a sight glass.

 

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