Humid gas consumption determining method

FIELD: instrumentation.

SUBSTANCE: humid gas consumption determining method is based on a relationship between a dilution degree of an indicator substance and a value of consumption of the measured substance at known consumption and initial concentration of indicator substance. With that, as the indicator substance, paramagnetic marks are used, and as an applied method, an electron paramagnetic resonance (EPR) method is applied.

EFFECT: improving accuracy of determination of percentage content of water and gas condensate in humid gas and correction of a reading of dry gas consumption converters as per analysis results of spectrum performance of samples taken from a humid gas flow.

3 dwg

The invention relates to measuring technique and can be used in gas and other industries for accurate measurement of gas flow, containing in its composition up to 10% (by volume) of water and gas condensate (hereinafter wet gas) during its transportation through the pipeline.

Known concentration methods of measuring the flow of liquids and gases. They are based on the dependence of the degree of dilution of the indicator or impurities from the flow rate of the material being measured Q₀at a known initial concentration of the indicator C_uand the amount of flow q_u. After sufficient mixing of the indicator with the measured substance downstream flow selected sample of fixed volume in which the measured concentration of the indicator C_x. The flow of the material being measured can be determined from the balance equation of the indicator:

$$Q_0{C}_0+q_u{C}_u=\left(Q_0+q_u\right)C_x,\left(1\right)$$

where C₀- possible initial concentration of the indicator in the measured substance.

If a₀=0 and C₀<<C_uthen

$$Q_0=q_u\frac{C_u}{C_x}\left(2\right)$$.

The method described in international standard ISO 2975-1 [1]. Its essence is described in more detail in many articles, for example [2].

Thus, for measuring the flow of liquids and gases are needed with high precision to determine the concentration of the indicator in the stream after mixing. For gases, containing in its composition up to 10% (by volume) of water and gas condensate, offered first to determine the above method, the flow rate of the liquid phase, and then to correct the readings of the transducers in the gas flow.

Depending on the substance of indicator methods are based on the following physical principles and methods of research: chemical, colorimetric, fluorometrically, refraction, conductometric. These methods are intended for one-time or periodic measurements of flow rate calibration/calibration standard constriction devices and other transducers in the gas flow.

For the first time as a matter of indicator applied paramagnetic labels of two different types. Due to its chemical structure and properties of one type of label is soluble only in water, is another type of label is soluble only in the gas condensate. The intensity of the EPR signal is proportional to the number of paramagnetic labels, decreases with decrease in the selected sample, and for a fixed volume of sample is proportional to the concentration of the indicator, With_xafter mixing [3]. Analyzing the EPR spectra of paramagnetic labels in the samples, it is possible to determine the flow rate of the wet gas in the stream.

The technical result of the invention is to improve the accuracy of the measurement results of the flow rate of the wet gas, the possibility of simultaneous determination of water content and gas condensate, wet gas, reducing the number of substance-indicator required for measurements in comparison with the methods described previously[1, 2, 4].

This goal is achieved due to the high sensitivity of the ESR method when determining the concentration of paramagnetic labels in the sample. In Fig.1 shows the dependences of the intensity of the EPR signal of the different types of paramagnetic labels on their concentration. Also, due to high sensitivity of the method, the EPR enough to enter into the flow of wet gas solutions with low initial concentration of paramagnetic labels that can reduce its costs during the measurement.

This method of simultaneous determination of water content and gas condensate, wet gas is very simple and intuitive thanks to the WMD, the EPR signals from various types of paramagnetic labels "exploded" (arise when different values of the constant magnetic field induction).

For wet gas in a horizontal pipe is layered character. In the lower part of the stream is the liquid phase of the wet gas consisting of water and gas condensate. The invention is illustrated in the drawing, is shown in Fig.2. In the wet gas flow, the current through the pipeline 1 of diameter D and passing through the Converter flow of dry gas 2, using injection systems 3 at a constant flow rate from the tank 4 injections solutions of paramagnetic labels with known initial concentration. After passing the stream a distance of not less than 100 D, which provides the necessary mixing of the pipeline using the sampling system 5 selected sample of the liquid phase of the wet gas.

The collected sample is placed in the microwave cavity of an EPR spectrometer, and registered its EPR spectrum. According to the intensity of the received spectrum is determined by the concentration of both types introduced upstream flow paramagnetic labels. The flow rate of the liquid phase present in the wet gas flow, is found from the balance equation of the indicator by the formula (1).

The efficiency of the method was determined in laboratory experiments using an EPR spectrometer Elexsys 500 Phi is we Bruker at a frequency of 9.5 GHz (which corresponds to a wavelength of 3 cm, X-band), amplitude modulation is 0.5 Gauss, the temperature is 300 K.

As paramagnetic labels were used in the experiments copper sulphate (copper sulfate) soluble in water, and spin label on the basis of nitroxyl radicals TEMPON, soluble in kerosene. The concentration of label in water and kerosene was achieved by mixing in an ultrasonic bath, the mass of the components was controlled by weighing on scales Vibra HT (abs.have been recovered. 1 mg).

Samples of the spin label, dissolved in kerosene, was placed in a glass capillary with an inner diameter of 1 mm using a long, thin pipette. Total sample volume of less than 5 μl, which allowed to maintain the quality factor of the microwave cavity at a reasonable level.

Samples of copper sulfate dissolved in water, were placed in a glass capillary with an inner diameter of 4 mm, the total volume of the sample did not exceed 0.5 ml

Also, experiments were carried out, during which the microwave cavity spectrometer simultaneously in different quantitative proportions were placed samples of copper sulphate in water and samples of the spin label in kerosene. On the EPR spectra (Fig.3) simultaneously present signals from both types of labels, the intensity of these signals varies according to the proportion of the two fluids in the cavity. The EPR signals from various types of paramagnetic IU is OK arise when the values of the magnetic field and 3450 3150 HS, respectively. The integral intensity of the signal decreases with the decrease of the number of paramagnetic labels in the selected sample. Comparing EPR spectrum of the sample of unknown concentration with a "calibration" spectra, it is possible to determine the concentration of both types of labels in the sample and, therefore, to determine the flow rate based on equation (2), and then to adjust the readings of the transducers of the gas flow, i.e., to determine the flow rate of the wet gas.

Sources of information

1. ISO 2975-1 "Measurement of water flow in closed channels. Methods of vaccination".

2. PP Kremlin. "Flow meters and counters", SPb.:

Polytechnic, 136-152 S. (2004).

3. R. S. Alger, Electron paramagnetic resonance: techniques and applications, New York, pp.201-221 (1971).

4. H. de Leeuw, Wet gas flow measurement by means of a Venturi meter and a tracer technique, the North Sea Measurement Workshop (1994).

The method for determining the flow rate of the wet gas based on the dependence of the degree of dilution of the substance of the indicator the rate of flow of the material being measured, at a known flow rate and initial concentration of the indicator substance, characterized in that, as a matter of indicator are paramagnetic labels, as well as the method used is the method of electron paramagnetic resonance (EPR), which allows high accuracy to determine the percentage of water and gas condensate, wet gas and adjust the readings of p is OBRAZOVATEL flow of dry gas through the results of the analysis of the spectral characteristics of samples selected from a stream of wet gas.