RU2309U1 - DEVICE FOR MEASURING THE CONTENT OF IMPURITIES, PREVIOUSLY OF SULFUR AND CHLORIDE SALTS, IN THE OIL FLOW - Google Patents

Abstract

A device for measuring the content of impurities, mainly sulfur and chloride salts, in the oil stream, including a measuring chamber made in the form of a cylindrical vessel with inlet and outlet pipes for connecting to the oil pipeline, inside of which a radionuclide source of neutrons enclosed in sealed envelopes are located and gamma scintillation detector, equipment for processing incoming measurement information and means for displaying and documenting measurement results, from characterized in that it is equipped with at least one thermal neutron detector enclosed in a sealed envelope, a radionuclide neutron source is placed in a container from a material that reduces the gamma radiation flux, and a scintillator of the gamma radiation detector is placed in a glass with a substance that reduces the thermal neutron flux.

Description

The utility model relates to the field of analysis of materials by radiation methods by measuring secondary emission using neutrons, and more particularly to devices designed for rapid measurement of impurities, mainly sulfur and chloride salts, in an oil stream, including on main pipelines in field conditions.

Known Device for Measuring Sulfur and Chloride Salts in an Oil Flow (Salahuddin Sheikh, SPE, Arabian American Oil Co., Albert P. Richter, SPE, Texaco Inc. Nuclear Salt-in-Crude Monitor, JOURNAL OF PETROLEUM TECHNOLOGU, MAY 1983) adopted for the prototype includes a measuring chamber and an instrument rack. The measuring chamber is a cylindrical vessel with inlet and outlet nozzles for connection to the oil pipeline. Two transverse tubes are welded into the vessel at a distance from each other, in the middle of one of which a neutron source is placed, and in the other a gamma-ray scintillation detector. The information coming from the gamma-ray detector is processed by special equipment located in the instrument rack, and the results of measuring the content of sulfur and chloride salts in oil are displayed on the scoreboard and documented.

The determination of sulfur and chlorine is carried out by registering capture gamma radiation in three energy ranges:

in the energy range, containing mainly the lines of capture gamma radiation of sulfur;

in the energy range containing the capture line of gamma radiation of chlorine;

in the energy range containing the lines of capture gamma radiation of hydrogen

with the subsequent determination from the system of equations for the sulfur and chlorine content in the oil in the measuring chamber. Moreover, the measured flux density of the capture gamma radiation in the energy ranges of sulfur and chlorine is normalized to the flux density of the capture gamma radiation in the energy range of hydrogen.

A measuring chamber made in the form of a cylindrical vessel with inlet and outlet pipes for connecting to an oil pipeline, a radionuclide neutron source and a gamma-ray scintillation detector, processing equipment for incoming measurement information, and imaging devices, enclosed in sealed shells and located inside the measuring chamber at a distance from each other and documenting the measurement results - the signs of the prototype, coinciding with the essential features of the claimed utility model.

The device is a prototype does not allow to reduce the relative error of measuring the content of sulfur and chloride salts in oil, except by using

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-gradionuclide source of neutrons with a large neutron flux, increase the measurement time or increase the number of gamma-ray detectors. However, the use of a radionuclide neutron source with a large neutron flux is limited by the permissible loading of the scintillation gamma-ray detector, at which its spectrometric properties are still preserved. The measurement time is limited by an allowable technological delay in obtaining regular information on the content of sulfur and chloride salts in the oil transported through the main pipeline. An increase in the number of gamma-ray detectors, as well as the use of a radionuclide neutron source with a large neutron flux, increases the cost of the device as a whole and complicates its design. At the same time, the prototype device lacks structural elements that could reduce the amount of the background component acting on the gamma radiation detector, and, therefore, reduce the relative error in measuring the content of sulfur and chloride salts in oil. In addition, the normalization of the measured flux density of capture gamma radiation in the energy ranges of sulfur and chlorine to the flux density of capture gamma radiation in the energy range of hydrogen is justified only if the density of the oil and the hydrogen content in it and the absence of microimpurities strongly absorbing neutrons in the oil are constant. Since variations in oil density and hydrogen content in it, as well as microimpurities strongly absorbing neutrons, are significant in Russian oil fields, the neglect of these factors will lead to

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an increase in the relative error in measuring the content of sulfur and chloride salts in oil.

Oil is and in the near future will remain the main raw material for the basic industries - energy and the chemical industry. In a market economy, the profitability of this industry largely determines the state of the country's economy as a whole. In turn, profitability significantly depends on the quality of raw materials, since the costs of transporting and refining oil and bringing the quality indicators of the final product to the norms established by national or international standards depend on it.

At the same time, quality indicators can have significant variations in their source (well, field), and oil from various fields significantly (by an order of magnitude or more) varies both in hydrocarbon composition and in the content of impurities. The main impurities that determine the commercial quality of oil are sulfur and chloride salts of sodium, potassium and magnesium chlorides. Their content in oil supplied to domestic refineries is regulated by GOST 9965-76 Oil. Degree of training for refineries. Technical conditions

Since the technological process of obtaining a particular product from oil depends on the class of oil established by GOST 9965-76, depending on the mass fraction of sulfur in crude oil, when transporting it through main pipelines at oil pumping stations, an express determination of the sulfur content in the oil flow should be made.

- identification of the oil class and the choice of transportation direction for the established time to the regions with the corresponding profiled oil refineries.

Whereas both the price of crude oil and the cost of its refining substantially depend on the sulfur content, the depreciation costs associated with the corrosion of oil pipelines, railway tanks and tanks of oil vessels depend on the content of chloride salts. According to GOST 9965-76, oil, depending on the content of chloride salts in it, is divided into three groups.

It follows from the foregoing that the prompt and accurate determination of these impurities in crude oil, both for the supplier and for the consumer, is an important element of the production process.

Thus, the task to which the claimed utility model is directed is to create a device for the rapid measurement of the content of impurities, mainly sulfur and chloride salts, in the oil stream, which would increase the accuracy of classifying the transported oil to the corresponding class or group according to national or international standards depending on the content of sulfur or chloride salts in it, which will contribute to the profitability of the industry.

When implementing the utility model, a technical result is achieved, expressed in the reduction of the relative error in measuring the content of sulfur and chloride salts in oil without using a radionuclide source of neutrons

with an increased neutron flux, an increase in the measurement time and an increase in the number of gamma-ray detectors.

In the known device, which is made in the form of a cylindrical vessel with inlet and outlet nozzles for connecting to the oil pipeline, a measuring chamber, inside of which at a distance from each other there is a radionuclide neutron source and a gamma-ray scintillation detector enclosed in airtight shells, equipment for processing incoming measurement information and means for displaying and documenting measurement results:

at least one thermal neutron detector is introduced, enclosed in an airtight shell;

a radionuclide source of neutrons is placed in a container from a material that reduces the gamma radiation flux;

the scintillator of the gamma radiation detector is placed in a glass with a substance that reduces the thermal neutron flux.

Distinctive from the prototype of the essential features of the claimed utility model:

placing a radionuclide neutron source in a container from a material that reduces the gamma radiation flux;

placing the scintillator of the gamma radiation detector in a glass with a substance that reduces the thermal neutron flux — they reduce the background component of the neutron and gamma radiation acting on the gamma radiation detector by absorbing its own gamma radiation from a neutron source in the container material and absorbing thermal neutrons in substance of a glass. This, in turn, provides a reduction in the relative measurement error

sulfur and chloride salts in oil without the use of a radionuclide neutron source with an increased neutron flux, an increase in the measurement time and an increase in the number of gamma-ray detectors.

The essential feature of the claimed utility model, distinctive from the prototype, that the device is equipped with at least one thermal neutron detector, provides information on the magnitude of the thermal neutron flux density in the measuring chamber used to normalize the measured flux density of capture gamma radiation in the energy ranges of sulfur and chlorine. Normalization of the measured flux density of capture gamma radiation in the energy ranges of sulfur and chlorine to the flux density of thermal neutrons in the measuring chamber makes the results of measuring the content of sulfur and chloride salts independent of variations in the density of oil and its hydrogen content, the presence of microimpurities strongly absorbing neutrons in the oil. This, in turn, also provides a decrease in the relative error in measuring the content of sulfur and chloride salts in oil without using a radionuclide source of neutrons with an increased neutron flux, increasing the measurement time and increasing the number of gamma radiation detectors.

Thus, the above set of essential features of the claimed utility model provides a technical result, which consists in reducing the relative error in measuring sulfur content and

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chloride salts in oil without using a radionuclide neutron source with an increased neutron flux, increasing the measurement time and increasing the number of gamma-ray detectors, in all cases to which the requested scope of legal protection applies.

The essence of the utility model is illustrated by drawings:

figure 1 shows a General view of the measuring chamber

sectional devices;

figure 2 shows the electrical structural diagram

devices.

A device for measuring the content of impurities, mainly sulfur and chloride salts, in the oil stream contains a measuring chamber (see figure 1), equipment for processing incoming measurement information and means for displaying and documenting measurement results (see figure 2).

The measuring chamber is made in the form of a cylindrical vessel 1 with input 2 and output 3 nozzles for the possibility of connecting it to the oil pipeline. The vessel is designed for internal pressure equal to the working pressure in the main pipeline. Inside the vessel in the diametrical direction and at a distance from each other, pipes 4, 5, and 6 are installed with plugged ends from the side of the internal volume of the vessel. The pipes are fixed in the walls of the vessel by welding and are designed for an external pressure equal to the working pressure in the main pipeline. A container 7 is located in the pipe 4, inside of which a radionuclide source is placed

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neutrons 8. A gamma radiation detector 9 is installed in the pipe 5, and its sensing element 10, a scintillator, is placed in a glass 11 with a substance 12 inside the pipe. A thermal neutron detector 13 is placed in the pipe 6. A container 7, which is a cylinder with an internal the cavity for accommodating the radionuclide source 8 is made of a material that reduces the gamma radiation flux. It uses lead or bismuth, the latter being more preferable due to the low level of capture gamma radiation when irradiated with thermal neutrons. The substance 12 located in the glass 11 reduces the flux of thermal neutrons. It is best used as lithium-containing compounds, for example, lithium carbonate, lithium fluoride and lithium phosphate due to the low yield of capture gamma radiation during radiation capture of thermal neutrons by lithium. The material of pipes 4, 5 and 6 should not contain elements with a large capture cross section of thermal neutrons in order to exclude a large level of capture gamma radiation. In this regard, the pipes are made of zirconium alloys, fiberglass or aluminum. A radionuclide source of neutrons should have a relatively soft neutron spectrum, a low level and energy of its own gamma radiation, and also a possibly long half-life. The closest to these requirements are radionuclide sources (americium-241 + boron) and California-252, which can be used in the device. The processing equipment for incoming measurement information includes two pulse discriminators 14 and 15 with energy thresholds corresponding to registration thresholds

capture gamma radiation of sulfur and chlorine, pulse counters 16, 17 and 18, measuring the number of discrete electrical signals received at their inputs during the measurement, and the computer 19.

Means for displaying and documenting the measurement results has a light display board or display 21 and a digital printing device 22.

The device connected to the pipeline works as follows.

Fast neutrons emitted by a radionuclide source 8 slow down to thermal energy on the hydrogen nuclei of the oil pumped through the vessel 1. Thermal neutrons are captured by the nuclei of elements contained in the oil, including sulfur and chlorine nuclei. The number of captures on the nuclei of a given element is proportional to the number of nuclei of this element per unit volume and the radiation capture cross section. After neutron capture by the nucleus, instantaneous emission of gamma radiation (capture gamma radiation) occurs. The spectrum of this radiation is linear and can contain from one (hydrogen) to several tens of lines (heavy elements). The energy and intensity of the lines are characteristics of the element. Gamma radiation is detected by a gamma radiation detector 9 having spectral sensitivity. Electrical signals from the gamma radiation detector 9 are fed to the input of the discriminator

14, which transmits pulses with an amplitude corresponding to an energy of about 4 MeV (sulfur threshold), and to the discriminator input

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the signals from the output of discriminators 14 and 15 are fed to the input of pulse counters 16 and 17, respectively, measuring the number of these signals during the measurement, after which the information in a digital code is transmitted to computer 19 for processing according to a previously entered program. Simultaneously with the registration of gamma radiation, the thermal neutron flux density is measured in the measuring chamber, which is used to normalize the measured flux density of capture gamma radiation in the energy ranges of sulfur and chlorine. Electrical signals from the thermal neutron detector 13 are fed to the input of the pulse counter 18 and, further, the information in a digital code is transmitted to a computer 19 for processing together with information on registration of capture gamma radiation.

The sulfur content of Cs and chlorine Cc1 (in g / kg) in oil is determined from the system of equations:

Be1 - Cs.Ssl + Ccl.Scll

ES2 Cs.Ss2 + Ccl.Scl2 (1)

where: Be1 and Me2 is the counting rate of the effect in energy

ranges containing capture lines of gamma radiation of sulfur and chlorine, respectively, imp / s;

Ssl and Sell are the detection efficiencies of sulfur and chlorine radiation, respectively, in the energy range containing sulfur capture gamma radiation lines, imp.l / sg;

and chlorine, respectively, in the energy range containing the capture line of gamma radiation of chlorine, imp.l / s.g.

The efficiencies Ssl, Sell, Ss2 and Scl2 are determined when calibrating the device.

The processing results in the form of the average value of the value of the content of sulfur and chloride salts in oil are displayed on the scoreboard 21 and are documented using a digital printing device 22.

Thus, the measurement using the claimed device the intensity of the group of lines in certain sections of the energy spectrum, allows you to determine the content of sulfur and chlorine in oil. In this case, the relative error in measuring the sulfur and chlorine content is determined by the expression:

S. () (2)

where: A is the coefficient of proportionality;

Q - neutron flux of a radionuclide source, neutron / s;

F is the cross-sectional area of the gamma radiation detector, sq.cm;

Nf is the count rate recorded by the gamma radiation detector from the background radiation component, imp / s;

-Is2A Mf 0.5

QF T

From formula (2) it is seen that a decrease in the relative error S without the use of a radionuclide neutron source with an increased neutron flux (i.e., without an increase in Q), an increase in the measurement time (i.e., without an increase in T), and an increase in the number of gamma-ray detectors (i.e., without increasing F) is possible only due to a decrease in the background radiation component Lf acting on the gamma-ray detector.

The total count rate recorded by the gamma radiation detector from the background radiation component is:

Nf N1 + N2 + N3 + N4 + N5 + N6 + N7 (3)

where: N1 - own gamma radiation of a radionuclide neutron source;

N2 - fast neutrons of a radionuclide source of neutrons;

N3 - thermal neutrons;

N4 - gamma radiation emitted during the capture of thermal neutrons by oil hydrogen nuclei;

N5 - gamma radiation emitted during the capture of thermal neutrons by nuclei of structural materials;

N6 - gamma radiation emitted during the capture of thermal neutrons by nuclei of uncontrolled impurities contained in oil;

N7 - cosmic radiation.

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removing the radionuclide source of neutrons 8 from the gamma-ray detector 9. Using pipes 4, 5, and 6 with structural materials with a small capture cross section of thermal neutrons or cladding them with a protective layer that absorbs thermal neutrons suppresses to some extent the background radiation component N5. The intrinsic gamma radiation of the radionuclide neutron source 8 (component N1) is attenuated by bismuth or lead from which the container 7 is made. This source, and finally, the effect of thermal neutrons on the gamma radiation detector (component N3), is reduced due to their absorption in lithium-containing substance 12 screening the scintillator 10 of the gamma radiation detector 9.

Therefore, by reducing the components N1 and N2, the total counting rate recorded by the gamma radiation detector is reduced from the background radiation component фф defined by expression (3), which, in turn, leads to a decrease in the relative error in measuring the sulfur and chlorine content s in accordance with the formula (2).

Further, in order to realize the possibility of normalizing the measured flux density of capture gamma radiation in the energy ranges of sulfur and chlorine to the thermal neutron flux density in the measuring chamber, it is necessary to measure the thermal neutron flux density over the entire volume of oil in the space between the radionuclide neutron source 8 and the detector gamma radiation 9 (i.e., multiple thermal neutron detectors), or at least one, most representative location (i.e., one

 (thermal neutron detector).

Uncontrolled variations in the properties of oil - density, which affects the attenuation coefficient of gamma radiation, hydrogen content, which affects the magnitude of the thermal neutron flux, content of non-analyzable elements in oil, which affects both the thermal neutron flux and the background radiation in the analyzed range capture gamma radiation energies - can lead to a significant increase in the error in determining the sulfur and chlorine content.

The estimates made at the enterprise showed:

possible variations in the oil density can lead to a change in the density of the gamma radiation flux in the range of 4-8 MeV at a distance of 40 cm from the neutron source within 7%;

possible variations in the hydrogen content in oil can lead to a change in the flux density of thermal neutrons in the hydrocarbon medium at a distance of 30 cm from the neutron source within 15%;

the appearance in oil of noticeable concentrations of elements with a large absorption cross section of thermal neutrons (boron, cobalt, cadmium, etc.) can lead to a decrease in the density of the flux of thermal neutrons in the measuring chamber by up to 45%.

However, if we normalize the values of the efficiency Ssl, Sell, Ss2 and Scl2, which are determined during the calibration of the device, and the counting rate of the effect Li1 and Li2, determined during the operation of the device, to the densities measured during calibration and operation, respectively

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-i6 thermal neutron flux in the measuring chamber, the result of measuring the content of sulfur and chloride salts in oil will not depend on possible variations in the density of oil, its hydrogen content and elements with a large absorption cross section of thermal neutrons. This reduces the relative error in determining the sulfur and chlorine content.

Thus, the introduction of at least one thermal neutron detector 13 into the inventive device, placement of a radionuclide neutron source 8 in a container 7 from a material that reduces the gamma radiation flux and placing the scintillator 10 of the gamma radiation detector 9 in the glass 11 with the thermal neutron flux reducing substance 12 provides a technical result - a decrease in the relative error in measuring the content of sulfur and chloride salts in oil without the use of a radionuclide source of neutrons with increased sweat com of neutrons, increasing the measurement time and increasing the number of gamma-ray detectors.

 9b (memory

Claims (1)

A device for measuring the content of impurities, mainly sulfur and chloride salts, in the oil stream, including a measuring chamber made in the form of a cylindrical vessel with inlet and outlet pipes for connecting to the oil pipeline, inside of which a radionuclide source of neutrons enclosed in sealed envelopes are located and gamma scintillation detector, equipment for processing incoming measurement information and means for displaying and documenting measurement results, from characterized in that it is equipped with at least one thermal neutron detector enclosed in a sealed envelope, a radionuclide neutron source is placed in a container from a material that reduces the gamma radiation flux, and a scintillator of the gamma radiation detector is placed in a glass with a substance that reduces the thermal neutron flux.