The method of measuring the dew point temperature and device for its implementation
(57) Abstract:Usage: in measurement technology, in particular for measuring the humidity of gases by the method of dew point. The inventive method for measuring the dew point is in the cooling section of optically transparent body, through which pass the light flux, and register the change in intensity of the light flux. The gas flow rate to the cooled area limit to the level determined by the diffusion of gas molecules. Measuring the dew point contains an optically transparent body 1, is connected to the emitter 5 and the Converter of the light flux 7, the cooler 9, the temperature sensor 8 and the sampling tube 10 mounted on the housing of the cooled area and set in the direction of the action of gravitational forces. The ratio of the area of the inner cross section of the tube S to the area of cooled surface area greater than 5, and l2/S > 25, where l is the length of the sampling tube. The tube end is made with a bevel. 2C. and 1 C.p. f-crystals, 1 Il. The invention relates to the field of measurement technology, in particular to measuring the humidity of gases by the method of dew point and can be used in the condensation specialists and indicators corrosion condense plot optically transparent body, through which pass the light flux, register the change of intensity of the light flux, which is judged on the occurrence of the dew point (ed. St. USSR N 593127, CL G 01 N 25/66, 1975).However, when using this method in the condensation hygrometers due to contamination of the cooled mirror is greatly reduced and the reliability.A device for measuring the dew point, contains two fiber with a pure heart, in the gap between the ends which has a condensing mirror, a condensing surface which is covered namachivayam film, the cooling unit and the Registrar dew point, and the bottom ends of the optical fibers are located in the plane of the condensing surface (patent USSR N 1806361, CL G 01 N 25/66, 15.01.90).However, when using this device possible contamination by impurities mirror, which reduces the measurement accuracy.The technical nature closest to the proposed technical solution is the method of measuring the dew point, which consists in the supply of the test gas in the cooled area of the optically transparent body, through which pass the light flux, and registration of the change and the sobe measuring the dew point, containing a cooled section of optically transparent body, enclosed in the housing and connected through the optical fibers with emitters and with the Converter of the light flux that is connected to the logger, cooler and temperature sensor (ed. St. USSR N 1744618, CL G 01 N 25/66, 06.06.89).A disadvantage of the known technical solutions is a low reliability due to possible contamination with impurities of the test gas is optically transparent body, may result in Vozniknovenie unnecessary layer, which can lead to inaccurate measurements and loss of efficiency.The technical result is to reduce possible contamination of the optically transparent body.For this purpose, the method of measuring the dew point, which consists in the supply of the test gas in the cooled area of the optically transparent body, through which pass the light flux, and registration of the change of the intensity of the light flux, which is judged on the occurrence of the dew point, the feed rate of the test gas in the cooled area of the optically transparent body limit to zero while maintaining the diffusion of molecules to the cooled section of the optically transparent body, and measuring the dew point, provided the switch and the Converter of the light flux, connected to the logger, a cooler and a temperature sensor, equipped with a sampling tube, one end of which is mounted on the housing around the cooled area of the optically transparent body, and the other set in the direction of the action of gravitational forces, moreover, the ratio of square internal cross-section of the tube to the surface area of the cooled area of the optically transparent body exceeds 5, and l2/S > 25, where l is the length of the sampling tube, S the area of its inner section. The sample tube is made with a bevel at the other end and set the bevel is opposite to the flow of the test gas.The essence of the invention lies in the fact that the creation of near-cooled section of optically transparent body of stagnant zones of the test gas before passing the light flux due to the introduction in measuring the dew point of the sample tube, restricting the gas flow rate to zero, and the implementation of registration of the change of the intensity of the light flux due to diffusion of the test gas to the cooled section of the optically transparent body can significantly reduce the pollution of the cooled area of the optically transparent body.Comparison predlagaemoj the significant features allows you to judge the fulfillment of the criterion of "inventive step", and the results of the model tests indicate the possibility of industrial use.The drawing shows the design of the proposed meter dew point.The method of measuring the dew point includes the supply of the test gas in the cooled area of the optically transparent body, through which pass the light flux, and the registration of changes in the intensity of the light flux, which is judged on the occurrence of the dew point. A special feature of this method is that before passing the light flux through a cooled section of optically transparent body form near him stagnant zone of the test gas by limiting the rate of gas supply to zero, and keep the diffusion of the molecules of the test gas to the cooled section of the optically transparent body.Create stagnant zones allows different impurities in the gas to be deposited on the surface of the cooled area of the optically transparent body, as well as gravitational forces act in the opposite direction, it contributes to maintaining the accuracy of the measurement of the dew point and hence increased reliability.The device has cooled section 1 optical Pro is OBRAZOVATEL 6 of the light flux, the output of which is connected to the recorder 7. In the housing 2 is installed the temperature sensor 8 and the cooler 9. The device is equipped with a sampling tube 10, one end of which is fixed on the housing 2 around the cooled section 1 optically transparent body and the other end is made with a bevel and installed in the direction of the action of gravitational forces. The sample tube 10 is installed slant opposite to the flow of the test gas and has three zones 11 13 transfer of molecules of the test gas to the cooling section 1.The device fits in the hole of the pipe 14 having a flange 15, is bonded with the pipe 14 by a locking connection 16.The sample tube 10 is installed slant opposite to the flow of the test gas, and the ratio of the area S of the internal cross section of the sample tube 10 to the area of Skthe surface of the cooled section 1 optically transparent body exceeds 5, and l2/S > 25, where l is the length of the sampling tube 10, S the area of its inner section.As the cooled section 1 optically transparent body can be used curved optical fiber, and the emitter 5 led type AL-B.And the Aza or mixture of gases the last act on the condensation surface of the cooled section 1 optically transparent body, in the absence of moisture condensation on the surface of the condensate is not allocated, and the flow of light from the emitter 5 to the optical fiber 3 passes through the cooling section 1 and the light guide 4, goes to the input of the Converter 6, but output it to the Registrar 7 nothing is supplied, indicating the absence of the condensate, and it does not register the temperature of the dew point.In the presence of moisture in the analyzed gas cooled section 1 optically transparent body at a certain temperature it forms a layer of condensate from melkodisperstnoy drops of spherical shape having a diameter commensurate with the diameter of the core of the applicable light guide 3. Due to the dispersion of the luminous flux surfaces of fine droplets of condensate intensity sharply decreases until complete dispersion and misses in the light guide 4. With the loss of luminous flux in the dispersion in the refrigerated section 1 optically transparent body Converter 6 outputs a signal to the controller 7, which records the occurrence of the dew point. The temperature of the cooler 9 is determined by the temperature sensor 8, the role of which can play a thermocouple connected to the galvanometer. The measured temperature and process automation, which yields this gas mixture.The leakage test gas in the sample tube 10 is on the opposite side of the bevel, thus protected from direct splashes, droplets and particles in the zone of the sensor. In the sampling tube 10 there are three zones 11 13 transmission of the test gas molecules to plot 1. Direct air cooling of the sample tube 10 by the gas flow causes turbulence inside her in the zone 11, which carry the molecules of the test gas, possible impurities, aerosols and solid particles in zone 12. The energy of the vortices is lost and in zone 12, the movement of the gases is laminar in nature, and bringing the gas into the zone 13 diffusive exchange of molecules, the presence of which leads to filtration of aerosols and trace contaminants present in the analyzed gas and aerosols and solids reach only zone 12 laminar flows, not penetrating into the diffusion zone 13 due to the impact of gravitational forces on them.If the length of the sample tube 10 is shorter than or equal to the sum of the lengths of the zones 11, 12, turbulent, and then laminar flow will bring aerosols and trace amounts of condensation on the surface of the sensor and cause contamination. Dvorni tube 10. If the sample tube 10 is cylindrical, then the sum of the lengths of the zones 11 and 12 does not exceed five diameters, i.e., if the length of the tube 10 to be shorter than five diameters, particles and aerosols from contaminating the mirror and cause a malfunction.If the sample tube has a cross section is not circular, then there is a limit of l2/S > 25, where l is the length of the sampling tube 10, S - the area of its inner section.For fixing the dew point without over-cooling the condensing surface is necessary in areas adjacent to the surface boundary layer of the sample gas to have the necessary number of layers of water molecules.Intensive dissipation of light energy gives this layer of water molecules, which is three times the wavelength of the light flux. Given that the number of water molecules in solid monolayer of 1 cm condensing surface 0,87 1015cm-2the diameter of molecules of H2O equal 0,348 nm, and the wavelength of the light energy introduced into the optically transparent body, is 900 nm, it is not difficult to determine that the required number of layers of water molecules for stable fixation of the condensing temperature is approximately equal to 3000, and the number of water molecules, which must be adjacent sensational surface Sk1 cm2the cooled section 1 optically transparent body).Condensation of water molecules in the diffusion zone leads to diffusion from the zone of laminar flow the same amount of molecules that condense.Therefore, at time t on the condensation surface is formed from the required number of layers of water molecules for stable fixation of the condensation temperature due to diffusion.The amount of mass of moisture transferred over time t due to the diffusion
< / BR>where m is the mass of moisture;
D is the diffusion coefficient;
S surface area, which passes through the diffusion, i.e., the inner section of the sampling tube;
t the time of the transfer;
the gradient of the density (concentration).Hence, the ratio should be greater than 5. When the ratio is less than 5 errors of measurement occur.Thus, in the proposed method and the device provided with high reliability and measurement accuracy by eliminating pollution. 1. The method of measuring the dew point temperature, which consists in the supply of the test gas in the cooled area of the optically transparent body, through which pass the light flux, and the registration of the action scene, the feed rate of the test gas in the cooled area optical prozrachnogo body limit to the level determined by the diffusion of molecules.2. Measuring the dew point temperature, containing a cooled section of optically transparent body, enclosed in the housing and connected through the optical fibers with the emitter and transducer of the light flux that is connected to the recorder, a cooler and a temperature sensor, characterized in that it is equipped with a sampling tube, one end of which is mounted on the housing of the cooled area of the optically transparent body and the other end installed in the direction of the action of gravitational forces, and the ratio of the area of the inner cross section of the sampling tube to the surface area of the cooled area of the optically transparent body exceeds 5, and l2/ S > 25, where l is the length of the sampling tube, S the area of its inner section.3. The device according to p. 2, wherein the sample tube is made with a bevel at the other end and set the bevel is opposite to the flow of the test gas.
FIELD: measurement technology.
SUBSTANCE: working body of indicator is made in form of thin metal membrane which is subject to cooling according to linear law by means of thermo-electric cooler. Direct measurement of temperatures of body and cooler is provided. At the moment of water vapor condensation the speed of cooling of membrane reduces abruptly due to consumption of cold used for cooling of moisture that condenses on surface of membrane turned to atmosphere.
EFFECT: improved precision of indication.
FIELD: measurement technology.
SUBSTANCE: device has two units. The first one combines mechanical units and has casing, connection tube with gas duct. The tube branches into the main one and internal one placed inside, electrically connected to each other. Filter collecting moisture is mounted on entry to the internal tube. The third tube having entry closed from the gas flow side is formed above the internal tube surface. The fourth tube is located in the third tube. The fourth and the third tube go out from the main one. The fourth one is connected to pump which outlet is separately connected to cooler and heater. Dielectric layers cover external surface of the third tube and internal surface of the fourth one. Its dielectric properties depend on moisture amount. The dielectric layers are covered with reticular electrodes bearing temperature gages attached to them. The second unit is electric circuit for shaping, processing and recording electric signal. It has generator, bridge circuit, differential amplifier, recorder and two-channeled amplifier.
EFFECT: high accuracy in concurrently measuring humidity and temperature.
FIELD: measuring technique.
SUBSTANCE: hygrometer comprises measurement chamber with sight and protecting glasses, pipelines for gas to be analyzed and cooling gas, cool conductor with condensation surface and temperature gage, base, throttle, and control members. The throttle may be mounted in the bottom section of the cool conductor with condensation surface or in the base.
EFFECT: enhanced accuracy of measurement.
2 cl, 2 dwg
FIELD: measurement engineering.
SUBSTANCE: controlled gas is subject to cool down due to passing it through layer of liquid, temperature of which liquid is kept equal to preset value of "dew point temperature for higher hydrocarbons". Correspondence of gas quality according to "of "dew point temperature for higher hydrocarbons" is determined by absence or presence of higher hydrocarbon film on surface of liquid. For the case, the liquid is chosen with density being higher than density of liquid state of hydrocarbons and in which liquid the liquid higher hydrocarbons do not solve. Water, diethylene glycol and methanol should solve in the liquid, which matter normally are present in controlled gas. Calcium chloride water solution of required concentration can be used as the liquid.
EFFECT: improved truth of quality control.
1 dwg, 1 tbl
FIELD: measuring technique.
SUBSTANCE: method comprises step cooling of solid body, maintaining a constant temperature at each step for a time period, and step cooling down to a temperature of onset condensation. The condensation temperature is determined from the formula proposed.
EFFECT: enhanced accuracy of measurements.
2 cl, 3 dwg
FIELD: measurement technique.
SUBSTANCE: humidity of natural gas is measured by means of dewpoint hygrometers. According to method, hydrate formation onto mirror is prevented due to introduction of vapors of fluid to gas coming for analysis into dewpoint hydrometer. Freezing point of fluid is lower than -80°C and tangent of angle of loss is small at measurement of dew point temperature by means of SHF/EHF hygrometer. Amount of vapor is measured from reduction in temperature of hydrate-formation at 8-10°C in relation to overload capacity of dew point temperature for tested gas. Methyl, ethyl, propyl alcohols or acetone are taken as fluid.
EFFECT: reduced systematic error; prevention of hydrate formation.
2 cl, 3 dwg
SUBSTANCE: invention concerns gas humidity measuring techniques. Hygrometer contains casing, coaxial source and receiver of light beams between which there is mounted flat optically transparent condensation mirror, temperature sensor and cooler unit. One version of hygrometer implies that condensation mirror is provided with not less than two through channels perpendicular to axis of source and receiver of light beams which lateral surfaces are parallel to condensation mirror planes. The second version of hygrometer implies that casing is provided with internal grooves, and condensation mirror with at least one through channel, and lateral surfaces of through channels being parallel to condensation mirror planes.
EFFECT: increased accuracy of measurements.
2 cl, 4 dwg
FIELD: physics; measurement.
SUBSTANCE: invention relates to measurement techniques and more specifically to measurement of humidity of gases particularly natural gas, containing a high level of technical trace constituents - compressor oil, vapours of desiccant alcohols (glycols), and higher hydrocarbons. Gas is passed over the cooling surface of a metallic mirror and the dew point temperature (DPT) is recorded. At operating pressure the gas is fed into an enclosed volume. Using the mirror, the entire gas is cooled to a temperature invariably lower than the dew point. Thermohygrometric equilibrium is established between the falling condensate and the surrounding gas and mass of the water precipitated on the mirror is measured. The absolute moisture content, adjusted to normal conditions, is found, corresponding to saturated gas at temperature of the mirror, using known tables or graphs which link humidity of gas with dew point temperature at operating pressure. The complete normalised humidity of the initial natural gas is calculated using a given mathematical relationship, and then using the same tables or graphs, the dew point temperature is found.
EFFECT: reduced errors.
FIELD: measurement equipment.
SUBSTANCE: invention refers to relative humidity sensors. In the device, metal chrome-plated mirror plate is provided with a number of conical vertical holes and conical metal movable electrodes with micrometric thread placed in them. Control of interelectrode gap is provided by movement of electrodes along axis of conical vertical holes. Moisture microparticles allow closing circuit of electrode with plate, which allows measuring dew point temperature.
EFFECT: providing sufficient accuracy in actual operating conditions.
FIELD: instrument making.
SUBSTANCE: low-temperature humidity metre includes light generator for formation of light flux, and two mirrors. At that, one mirror is equipped with cooling system with thermometre to cool its surface when dew point value is being determined. Temperature of the other mirror is kept stable and equal to the temperature of layers enveloping its atmospheres. As light generator there used is semiconductor laser or laser diode, or light-emitting diode, or luminescent diode generating light flux. On the way of light generator there located is plane convex lens. Light flux after the lens interacts with divider so that it can be split into two beams of equal intensity. Beams are directed through plane convex and rod lenses to the appropriate mirrors. On the way of light fluxes reflected from surface of mirrors there installed in series are plane convex lenses and photodetectors. The latter generate the signals proportional to intensity of light fluxes. Outputs of the above photodetectors are connected to the appropriate two inputs of information processing unit. The third input of information processing unit is connected to the output of semi-conductor thermometre. Outputs of the above unit are connected to information board and to cooling system. At that, light flux on its way from light generator to photodetectors is enclosed in light guides.
EFFECT: enlarging the range of working temperatures, improving measurement accuracy.
7 cl, 1 dwg