RU87544U1 - THREE-COLOR LED RADIATOR OF THE MIDDLE INFRARED AREA OF THE SPECTRUM FOR MEASURING THE WATER CONTENT IN OIL AND OTHER INHOMOGENEOUS LIQUIDS - Google Patents

Abstract

A mid-infrared three-color LED emitter for measuring the water content in oil and other non-homogeneous fluids, consisting of an eight-pin TO-39 housing, which has a built-in thermo-cooler, a thermistor and three LED chips glued to its cold end: LED16 measuring LED chip for oil , a measuring LED chip for water LED19 and a reference LED chip LED22, the anodes and cathodes of the LED chips are connected by gold wires to four external leads of the TO-39 case: first, second m, third, sixth; the findings of the thermo-refrigerator and thermistor are connected with the fourth, fifth, seventh and eighth external terminals of the TO-39 housing, to which a parabolic reflector with a KI quartz glass window is welded.

Description

The utility model relates to devices emitting incoherent electromagnetic waves in the mid-infrared range (1.6-5.0 μm), and can be used for optical spectroscopy of multicomponent liquids in the maximum intensity range of characteristic absorption lines of chemical substances. The main areas of application are the measurement of water in crude oil, petroleum products and other non-homogeneous liquids.

Existing methods for measuring moisture in crude oil and petroleum products are based on various physical and chemical principles. The separation methods for controlling the water cut of crude oil include methods based on gravity sedimentation, centrifugation, heat and cold treatments, microwave and ultrasonic separation, separation under the influence of a constant electric field. Two of the most common methods at the moment are azeotropic distillation and centrifugation (separation due to centrifugal forces). In the azeotropic distillation method (Dean-Stark method) (GOST 2477-65), an oil sample is poured into a flask and a dried solvent, usually gasoline or toluene, is added to it. A reflux trap is inserted into the flask. All this is installed on the heater. During heating, water in a vaporous state, together with the solvent, enters the reflux condenser. In it, water and solvent vapors condense and flow into a trap, where they are divided into two layers due to the difference in densities. Excess solvent is returned from the trap to the flask through the tube. Distillation is continued until the water level in the trap stops changing. This method has a negative systematic error, leading to an underestimation of the measurement result and due to a partial loss of moisture on the walls of the refrigerator and its dissolution in gasoline. With a moisture content of 0.1-1%, this error can reach 7%. The accuracy of the method can be improved by increasing the volume of the oil sample, which determines the moisture content. However, this technique leads to an increase in the duration of the analysis, which can already reach 1-1.5 hours. The centrifugation method is based on the separation of a multicomponent liquid in accordance with the different densities of the individual components when the sample is rotated at high speed. The analysis time for this method is shorter than with the azeotropic distillation method (about 20-30 minutes), but the accuracy is significantly worse (error about 10%).

As an alternative method, near-infrared spectroscopy is increasingly being used. It is known that oil and its refined products are a complex mixture of hydrocarbons of various classes having absorption bands in the near-IR spectral region. Studies of absorption spectra make it possible to determine the content of water and other substances in oil and oil products. The equipment for IR analysis of oil mixtures based on IR spectrometers is currently produced by the German company Bruker, the Israeli company PetroMetrix and several other companies. However, such equipment is large in size, high in cost, the analysis process is quite complicated and therefore is used only in special laboratories.

At the moment, there is no possibility of carrying out quick and sufficiently accurate measurements of the water content in crude oil using a portable device in wells and in areas of primary oil refining.

The objective of the proposed technical solution was to create a new three-color LED emitter of the mid-IR spectral range with a built-in thermal refrigerator. Such a compact emitter (diameter 9 mm) is a key element for creating portable IR analyzers for the content of water in oil, oil products and other non-homogeneous liquids. In this case, it is necessary to simultaneously control the characteristic optical absorption of water and a mixture of hydrocarbons. For inhomogeneous liquids, the attenuation of the signal when passing through the measured medium also strongly depends on the optical scattering at the boundaries of the two phases of the water-oil emulsion. Therefore, the optimal measuring circuit should contain three channels: measuring for water (at a wavelength of maximum absorption of water), measuring for oil (at a wavelength of maximum absorption of oil) and reference (at a wavelength where the absorption of water and oil are close in value and minimal) .

Using a series of experiments (Fig. 1), LEDs were selected for three channels: measuring for water - LED 19 (maximum emission spectrum at 1.94 μm), measuring for oil - LED 16 (maximum radiation spectrum at 1.65 μm) and reference - LED22 ( maximum emission spectrum at 2.20 μm). The results of measuring the water content in oil and other liquid media using optical IR analysis are significantly affected by temperature changes. Therefore, the design of a three-color LED emitter also includes a miniature thermo-holodilik and a thermistor (figure 2). Measuring the differential difference in the ratio of signals from two measuring and reference sources ensures the stability of the results when changing the main external factors.

A key element of the three-color LED module are LED heterostructures based on narrow-gap A ³ B ⁵ semiconductor materials. The wavelength of the LED radiation is determined by the band gap, that is, the composition of the solid solution in the active region. For an LED with a maximum radiation at 1650 nm, an AlGaAsSb quaternary solid solution with an aluminum content of 3% is used in the active region. For an LED with a radiation maximum at 1940 nm, a GaInAsSb quaternary solid solution with an indium content of 9% is used in the active region. For an LED with a radiation maximum at 2200 nm in the active region, a GaInAsSb quaternary solid solution with an indium content of 19% is used. In all cases, a wide-gap AlGaAsSb solid solution with an aluminum content of 64% is used as an electronic limitation. The structures are grown on GaSb substrates by liquid phase epitaxy (LPE) or gas phase epitaxy from organometallic compounds (MOCVD).

Using photolithography, heterostructures are used to form LED chips ranging in size from 0.3 × 0.3 mm to 1.0 × 1.0 mm. Then the chip is mounted on a ceramic or silicon substrate ranging in size from 0.8 × 0.8 mm to 2.0 × 2.0 mm.

A three-color LED emitter for measuring water in oil is shown in FIG. 2.

LED emitter includes:

1 - measuring LED chip for oil LED 16

2 - measuring LED chip for water LED 19

3 - reference LED chip LED22

4 - parabolic reflector

5 - ceramic substrates

6 - thermistor

7 - thermo-refrigerator

8 - KI quartz glass window

9 - TO-39 building.

The module is mounted in a 9 mm standard TO-39 package with 8 pins (9). A thermo-refrigerator (Peltier element) built-in to the housing (3 × 3 mm in size) (7) provides a temperature difference between the hot and cold ends without load of at least 60 degrees. A temperature sensor - a thermistor (6) is glued to the cold end of the thermo-refrigerator. Three LED chips already mounted on the substrates, emitting at the wavelengths of 1650 nm (LED16), 1940 nm (LED19) and 2200 nm (LED22) (1, 2 and 3) are glued to the free surface of the cold end of the thermo-refrigerator. The anodes and cathodes of the LEDs are connected by gold wires with four external terminals 1-3, 6 of the TO-39 housing (Fig. 3). The findings of the thermo-refrigerator and the thermistor are connected to the external terminals 4, 5, 7, 8 of the TO-39 housing. A parabolic reflector with a window with a diameter of 15 mm is welded to the body to narrow the radiation pattern of the emitter.

Pulse power of the three LED channels of the emitter, control and stabilization of temperature is carried out using an electronic circuit. The electronic circuit is not part of the claimed design; various embodiments of the electronic circuit are possible.

The measurement of water content in oil and petroleum products using a three-channel emitter is as follows.

First you need to turn on the temperature stabilization of the three-color LED emitter. Temperature stabilization allows to ensure the accuracy of measurements in a wide range of ambient temperatures (-20 ÷ + 30 ° C). The electronic circuit provides access to the desired temperature and stabilization in automatic mode. Then the pulse power of the measuring and reference channels is turned on, the values of three signals are recorded in the processor memory when the rays pass in the absence of the test sample. S ₁₆ ⁰ - signal of the LED chip LED16, S ₁₉ ⁰ - LED19, S ₂₂ ⁰ - LED22. Thus, using the signal conversions below, you can eliminate errors associated with a possible change in the power of the LEDs or other parameters of the device or the environment over time. After that, the radiation is passed through the test sample, while the measured signals S ₁₆ ^and (LED16), S ₁₉ ^and (LED19), S ₂₂ ^and (LED22) of three channels are entered into the processor memory. The measured signals are processed, the relative signals S ₁₆ = S ₁₆ ⁰ / S ₁₆ ^and , S ₁₉ = S ₁₉ ⁰ / S ₁₉ ^and , S ₂₂ = S ₂₂ ⁰ / S ₂₂ ^and , as well as the difference in the ratios S = S ₁₆ / S are calculated ₂₂ -S ₁₉ / S ₂₂ . Then, using the known calibration dependence of the water concentration C on the difference in the relations S C (%) = f (S), the percentage of water in the test sample is determined.

A prototype of the claimed device was manufactured and tested. This tri-color LED emitter with built-in thermo-refrigerator for the mid-IR region of the spectrum is characterized by compactness and unity of design. In a 9 mm case the size contains three different LED emitters (two measuring and reference), a thermo-refrigerator and a thermistor. This design of the device has no direct analogues in the mid-IR region of the spectrum; in existing devices for implementing a two-, three-channel scheme based on thermal or re-emitting sources, significantly more dimensional optical systems are used. The small distance between the chips provides the same operating conditions for the three channels, which is an important advantage of this design compared to conventional three-channel circuits. The maximum wavelength of the radiation and the half-width of the radiation spectrum is determined by the parameters of the heterostructure itself, and not by an external optical filter. The lifetime of LEDs of 80,000-100,000 hours significantly exceeds the lifetime of other types of sources of infrared radiation. The well-known process of slow degradation of the power of semiconductor LEDs occurs equally for three chips of the same type of structure, which ensures the stability of the differential signal for 8-10 years. The design allows you to select the total temperature for the three emitters in the range of -10 ÷ + 20 ° C and maintain it constantly with minimal electrical power. The small size and high efficiency of the thermo-refrigerator allow keeping the temperature close to room temperature with a constant current of about 10 mA. The tri-color LED module with built-in thermal refrigerator for the mid-IR spectral range meets the requirements of portable optical analysis.

The positive effect of the claimed utility model in comparison with devices that determine the concentration of water in oil and oil products using azeotropic distillation methods (Dean-Stark method), centrifugation, and other physical methods currently used is primarily in the speed and simplicity of measurements. Compared with the currently used methods of IR spectroscopy, the positive effect of the claimed utility model lies in the low cost, portable size and ease of measurement. Compared to heat sources and sources based on re-radiation for the mid-IR region, the positive effect consists in an increased service life of continuous operation (80,000-100,000 hours), high speed (rise and fall times of less than 50 ns), and the absence of the need to use additional optical filters. The presence of three radiation channels makes it possible not only to simultaneously control the optical absorption of water and a mixture of hydrocarbons, but also to take into account the optical scattering at the interface between the two phases of the water-oil emulsion, which is characteristic of inhomogeneous liquids. The flexibility of heteroepitaxy technology and the miniature size of the LED chips made it possible to realize a unique design, where a thermo-refrigerator, a thermistor and three emitters are combined in one standard 9 mm case. For the considered analogues, the implementation of such a miniature design is in principle impossible.

Claims (1)

A mid-infrared three-color LED emitter for measuring the water content in oil and other non-homogeneous fluids, consisting of an eight-pin TO-39 housing, which has a built-in thermo-cooler, a thermistor and three LED chips glued to its cold end: LED16 measuring LED chip for oil , a measuring LED chip for water LED19 and a reference LED chip LED22, the anodes and cathodes of the LED chips are connected by gold wires to four external leads of the TO-39 case: first, second m, third, sixth; the findings of the thermo-refrigerator and thermistor are connected with the fourth, fifth, seventh and eighth external terminals of the TO-39 housing, to which a parabolic reflector with a KI quartz glass window is welded.