The detector dew point

 

(57) Abstract:

The invention relates to measuring technique and is intended to determine the dew point of the gaseous mixture, mainly of hydrocarbons. It can be used in technological devices petrochemical production, gas transport, as well as in the development of gas-condensate and gas fields. Essence: in the device source and the radiation detector optically connected with the cooled surface of the mirror through the optical fiber, and a radiation source optically connected with the core of the fiber and the radiation detector with the sheath of the fiber, the diameter of the shell does not exceed the diameter of the mirror. 1 table, 1 Il.

The invention relates to the physical dimensions and may find application in the oil and gas industry, meteorology and other fields of science and technology, where necessary moisture measurement gas.

Establishing the parameters under which condensation occurs formation of hydrocarbon gas mixtures, which can significantly improve the efficiency of operation of gas-condensate fields, to reduce the loss of condensate, a valuable hydrocarbon cheese is the most sensitive and low-inertia are optical detectors dew condensation hygrometers. They are based on the principle of measurement of luminous flux reflected from the surface condensation or passed through it, and check the dew point at the moment of changing intensity of the light flux. A number of optical detectors dew [1, 2, 3] contains placed in a controlled gas-cooled flat mirror, a light source, a cooling device, a sensor and a temperature Converter.

Detectors dew flat mirror have insufficient sensitivity in the determination of the dew point. This is because the process at which condensation is the formation of primary droplets on a separate randomly distributed centers of condensation, which are separate microscopic depressions or grooves on the condensation surface [4] Therefore, the condensation may begin on any part of the cooled mirror, for example in the wrong place, where the reflection of the light flux. Consequently, a further cooling of the surface of the mirror to achieve the attenuation of the intensity reflected from the mirror radiation. Due to the fact that the steam condenses on the surface, cooled with a certain pace, i.e. in the absence of thermodynamicist the cooling surface is a flat mirror with the aim of consistent detection of dew significantly reduces the accuracy in determining humidity: 10% for each degree of hypothermia [6] the Disadvantage of the traditional optical detectors flat condensation surface is also a narrow range of humidity control, namely, the lower limit of the chapel measurement of dew point, especially at low temperatures, due to the fact that under these conditions, changes dramatically the density of the crystals on the condensation surface: the condensate is rare, but large "Islands" that may not be in the field of view of the detector. The practical lower limit of conventional optical detectors at low temperatures is limited by the moisture content of 25-35% [7]

Higher sensitivity have hygrometers, optical detectors dew which contain reflective condensing surface in the form of a surface of the second order, providing invariance detection of dew from all over the surface to be cooled. Known, for example, hygrometers [8, 9, 10] in which the reflective surface is made in the form of powellites rotation, in one of the foci of which is the source and the second radiation detector. However, the detectors dew these hygrometers have the disadvantages inherent in this type of constructions, namely:

the complexity of manufacturing the reflective surface;

the complexity of maintaining the same temperature on the surface condensation due to its relatively large size;

stringent requirements on the alignment of the source and the photodetector;

greater intensity reflected from the entire condensing surface signal does not allow to detect the first drops of condensate, as their appearance is slightly weakens the reflected signal. Therefore, to noticeable changes of the output signal requires a large amount of condensate, i.e. a further reduction in temperature.

All of these listed features detectors dew elliptic mirror cause loss of precision measuring dew point. In addition, for each specific disadvantages.

The closest technical solution to offer a greater number of common features is the detector hygrometer dew point containing a cooled surface in the form of a concave spherical mirror, a light source placed on the side of the optical axis of the mirror, two photodetectors, one of which is installed in the focal plane of the mirror, two temperature-sensitive elements, one of which is placed in the zone of the cooler [11]

When known the benefits of this hygrometer he has insufficient tondemo surface radiation, excluding the tracking of the first drops of condensate due to excessive brightness of the optical spot.

The objective of the invention is to improve the accuracy of determining the temperature at which condensation by reducing the degree of supercooling controlled mixture of gases.

The technical result, which sent the invention consists in the exclusion of focusing reflected from the cooled spherical mirrors radiation on the entrance window of the photodetector, thereby enabling to detect the first drops of condensate and to improve the accuracy in determining the temperature at which condensation of a mixture of gases.

The task and the technical result is achieved by the fact that the detector dew point containing a cooled metal surface in the form of a concave spherical mirror, measuring the temperature of this surface, microglial, the source and the radiation detector, optically coupled with the surface of the mirror, and the radiation source is selected in the focus of the mirror, unlike the prototype source and the radiation detector optically connected with the mirror surface by using the optical fiber, and a radiation source optically connected with the core of the fiber and the receiver the way, the invention meets the criterion of "novelty".

Patent research showed that in all known devices to control all of the cooled mirror surface is focusing reflected from the surface to be cooled radiation on the entrance window of the photodetector (ed. St. USSR N 315999, 1969; 397830, 1973; 359994, 1976; 642665, 1979; 661485, 1979; 819648, 1981 , 885589, 1981; 979978, 1982; 1073668, 1984; 1569565, 1990; U.S. Patent N 4435091, 1984; application UK: N 1297296, 1978; 2043242, 1980). Focusing reflected from the cooled mirror radiation degrades the sensitivity of the detector due to excessive brightness of the optical spot on the entrance window of the photodetector, eliminating the tracking of the first drops of condensate, slightly weakening the intensity of the reflected signal.

The use of the invention allows to achieve a result that meets the need.

Thus, the invention meets the criterion of "inventive step".

The drawing shows the design of the device.

The detector dew point consists of a short metal housing 1 in which is placed the shell 2 and the core 3 fiber-optic light guide. The detector is equipped with a temperature measuring unit 4, which with the maturity of 5 to Windows 6 for controlled pumping of gases. At the bottom of this cavity is mounted a concave spherical mirror 7, the temperature of which is controlled by thermocouple 4, and microglial 8. Out of control (in the field of atmospheric pressure), the fiber is divided into the shell and the core, protected by a rubber coating 9 and 10. The radiation source 11 (for example, led AL-107 or semiconductor laser ILPN-109), the sensor 12 (e.g., PD-8K) placed in special holders 13 and 14 are installed on the front panel of the secondary device. When the radiation source is associated with the core fiber and a radiation receiver with a sheath of the fiber, the diameter of which does not exceed the diameter of the cooled mirror.

The detector dew point operates as follows.

The detector is installed in the housing of the measuring chamber by means of threaded connections and seals the controlled environment using a blade seal. The radiation source 11 generates an optical signal of the infrared range, which core 3 of the fibre falls on a concave mirror, is fixed by soldering on Mikrokreditna type TAMO-8. While the core 3 of the optical fiber placed in the focus of the mirror 7. The mirror 7 is formed by the ode. Because the diameter of the shell does not exceed the diameter of the cooled mirror, and thus, the beam reflected from mirror rays on the shell falls on the photodetector. For controlling the operation of the emitter in the secondary device, which has a radiation source, the support channel included in the scheme, comparing the sent and received signals. In the initial state in the absence of condensate on the mirror 7, these signals are balanced.

At lower temperature controlled environment due to the adiabatic expansion of the gas (as is the case in the test chambers pipelines) or due to the inclusion of microblades 8 the temperature of the mirror 7 is reduced. This is indicated by thermocouple 4, placed near the mirror. When the condensation on the cooled surface of the concave metal mirror 7, the intensity of the reflected laser radiation is sharply reduced due to double scattering: primary scattering on microcaps incident on mirrors radiation and secondary scattering passed through the condensate and reflected from mirrors radiation. In addition, the molecular absorption of radiation in the condensate layer is greater than in Gaza. The decrease in intensity of halogen with exceptiona the Ala offset in the comparison circuit, which is the dew point temperature. This signal can be monitored and the pressure at which detects the occurrence of condensation. As follows from the description of the operating principle of the proposed detector, an electronic circuit generally follows the scheme presented in the device selected for the prototype [11] the Device as a sensing element in the proposed detector is very easy to implement and reliable in operation. First of all greatly simplified aligning concave mirror relative to the radiation source: moving cylindrical cavity 5 with the mirror 7 to the screw thread of the housing 1, to achieve the maximum reflected signal and fix this situation. No offset relative to each other of the core and shell eliminates the need to align the positions of the source and the radiation detector, as is the case in the prototype. Hard, fixed layout elements of the optical system of the detector, its minor dimensions: h mm allow you to place it in high-pressure installations. The detector can be used in the pressure range of 0.1-20 MPa, in the temperature range 253-373 K. Expanding range of applications in Otley is s thus from exposure to low temperatures and high pressures. Unlike the prototype of the proposed detector excluded focusing reflected from the cooled mirror radiation, which does not allow to detect the first drops of condensate, as their appearance is slightly weakens the intensity of the reflected pre-focus signal.

The detector proposed design was tested in a high pressure autoclave when determining the parameters of the condensation of n-pentane. The table shows the results of measurements and comparison with literature data [12]

You can see that the comparison of test data with tabular [12] confirms the reliability and greater functionality of the proposed detector. The test device [11] is selected prototype, in similar conditions was not possible due to the fact that the detector prototype is designed for normal pressure.

When dimensioning the condensation of explosive gases, such as mixtures of hydrocarbons at high pressures, the temperature of the controlled environment reduced by adiabatic expansion of gases. Power microblades in this case should be disabled. Otherwise, the detector remains the same.

Sources Who USSR N 256500 G 01 N 21/50, 1970.

3. The UK Patent N 2043242 G 01 N 25/68, 1980.

4. Tanaka H. Theoretical study of drip condensation. - "Heat transfer". So 101, No. 1, 1979. 72-79 C.

5. Umur A. Griffith R. Mechanism drip condensation. -"Heat transfer". So 101, No. 1, 1979. 135-144 C.

6. Berliner M. A. Status and direction of development of means of measurement and automatic control of humidity abroad. M Tsniiteneftehim, 1967. 21-81 C.

7. Zaitsev C. A. and other air Humidity and its measurement. L. Gidrometeoizdat, 1974. 38 C.

8. USSR author's certificate N 115828 class. 42 e, 416, 19567

9. French Patent N 2196977 G 01 N 21/006, 1974.

10. USSR author's certificate N 359994 G 01 N 25/66, 1974.

11. USSR author's certificate N 1460685 G 01 N 25/66, 1989 (prototype).

12. Vargaftik, N. In. Handbook of thermophysical properties of gases and liquids. M State. publishing house of physical-matemat. the literature dealing with. 1962. 202 C.

The detector dew point containing a cooled metal surface in the form of a concave spherical mirror, measuring the temperature of this surface, microglial, the source and the radiation detector, optically coupled with the surface of the mirror, and the radiation source is selected, the focus of sea, moreover, the radiation source optically connected with the core of the fiber and the radiation receiver with a sheath of the fiber, the diameter of the shell does not exceed the diameter of the mirror.

 

Same patents:

The invention relates to measurement techniques, in particular to control the degree of moisture contamination of the surfaces of the insulators in electrical installations, as well as the friction surfaces of various machines and mechanisms

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.

4 dwg

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.

2 dwg

Hygrometer // 2280249

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

FIELD: physics.

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.

3 dwg

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.

1 dwg

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

Up!