WO2013189124A1

WO2013189124A1 - Method of determining material-level curve in continuous-type passive nucleonic level gauge

Info

Publication number: WO2013189124A1
Application number: PCT/CN2012/080196
Authority: WO
Inventors: 郭云昌; 朱敏娟
Original assignee: Guo Yunchang; Zhu Minjuan
Priority date: 2012-06-19
Filing date: 2012-08-16
Publication date: 2013-12-27
Also published as: CN102735313B; CN102735313A

Abstract

A method of determining the material-level curve in a continuous-type passive nucleonic level gauge (3), said method utilizing a direct method and comprising the following steps: first disposing the continuous-type passive nucleonic level gauge (3) in a designated position; then using other measurement means to determine the material level and, depending on measurement precision requirements, measuring the intensity of gamma rays corresponding to various material levels at points where material levels vary; and, finally, determining the material level on the basis of the actual measurement of the gamma ray intensity. An algorithm method or reference method can also be used instead of a direct method. The present invention fills a gap in the prior art by providing a method to be used with a continuous-type passive nucleonic level gauge (3) to determine the relationship between material levels and gamma ray intensity. The present invention provides a basis for accurately determining material levels by setting forth three alternative methods, i.e. a direct method, an algorithm method and a reference method, to be used depending on actual measurement conditions. The methods provide more measurement options for users depending on actual measurement conditions and, when used as testing methods, improve data reliability.

Description

Method for determining material level curve in continuous passive nuclear material level gauge

[Technical Field] The present invention relates to the field of passive nuclear material level measurement technology, and in particular, to a method for determining a material level curve in a continuous passive nuclear material level gauge.

[Background technique]

In the chemical, metallurgical, coal, electric power and other industries, in the process of conveying materials, it is often necessary to measure the material level in the hopper and silo. There are two main methods for measuring the level using gamma ray: one is a conventional nuclear level meter with a radioactive source, such as an automatic level control device disclosed in the domestic patent CN202230393, which essentially utilizes left and right mutual A symmetrical gamma ray column measures the level of the material in the material level bin; the other is a non-radio source nuclear level meter that uses the natural gamma ray to measure the level of the material and the environment without the source. , referred to as the passive nuclear material level meter, the passive nuclear material level meter makes it easy to realize the non-contact measurement level without using the radioactive source but only by using the gamma radioactivity of the measured material itself and the gamma radioactivity in the environment of the tested container. Effective and feasible, the field that originally needs to use the nuclear level gauge is replaced by a passive nuclear level gauge, which greatly reduces the number of radioactive sources used, eliminates the high cost of radioactive source management, and reduces the radiation risk.

According to the alarm mode of the material level measurement, the passive nuclear material level can be divided into two types: switch mode and continuous type. The switch type passive nuclear level gauge is a level meter that can only distinguish whether the material height reaches the set position and outputs a switching signal; and the continuous level meter can distinguish the specific material height and output one or A level meter for a variety of continuous level signals. For the continuous passive nuclear level gauge, the material level curve is the corresponding relationship between the material height and the gamma ray intensity. Therefore, the determination of the material level curve plays a very important role in accurately determining the material level. Such as The domestic patent CN200810017274 provides an ideal calculation method which is very inconsistent with reality and is used to calculate the corresponding curve of the level and the measured radioactivity. For the convenience of calculation, the method firstly simplifies the bulk radioactive source into a planar radioactive source, and then simplifies the position of the measuring point on the side of the bulk radioactive source to a point above the planar radioactive source, and finally expands the ideal situation above the plane to a point. In the actual application that does not conform to the ideal model, the trend of the curve thus calculated is opposite to the actual when the measuring point is close to the material interface, so there is no practical value. Another method disclosed in the domestic patent CN03115824 for measuring the level using natural radioactivity is characterized in that, in the case of a known material level, the material is gradually increased, and the gamma ray radiation intensity is continuously measured to obtain the material height and gamma ray emission. A point where the intensity corresponds one-to-one, connecting all the measurement points to obtain a continuous curve, that is, the material level curve. The applicable premise of the method is the known material level, and the material level at each moment is known, but in actual cases, the method is difficult to achieve for three reasons: First, the material level cannot usually be accurately known in time; Second, in order to compare Accurate gamma ray intensity values require a certain response time. Third, due to the randomness of gamma rays, the actual measured gamma ray intensity value is a range.

[Summary of the Invention]

The object of the present invention is to make up for the deficiencies of the prior art and to provide a method for accurately determining the material level curve in a continuous passive nuclear level gauge.

In order to achieve the above object, a method for determining a material level curve in a continuous passive nuclear level gauge is designed, which comprises a measuring device and a calculation module, characterized in that the method adopts a direct method and comprises the following steps:

(a) Install the continuous passive nuclear level gauge at the selected position so that the installation height meets the height requirements of the alarm. The installation direction is such that the gamma ray detector can detect the material to be tested and the container to be tested. Gamma ray intensity;

(b) Record the intensity of the gamma ray measured by the continuous passive nuclear level gauge and its range of variation at any known level within the measurement range, and obtain a line segment on the level of the level and the gamma ray intensity plane. ; (c) Change the material level according to the required measurement accuracy, record the intensity of the gamma ray measured by the continuous passive nuclear level gauge and its variation range, and obtain another line segment on the level of the level and the gamma ray intensity plane;

( d ) repeat step (C) ;

(e) connecting the maximum point of the obtained line segment, and then connecting the minimum point of the obtained line segment, to obtain the change trend of the gamma ray intensity corresponding to different material positions, that is, a relatively thick material level curve;

(f) According to the material level curve, the range of the material level is obtained according to the actual measured gamma ray intensity, and the middle value is the measured material level.

The method uses a push algorithm instead of the direct method and includes the following steps:

(a) Linear fitting calculation, measuring the gamma ray intensity Nh when the material is full (the material level is H); and measuring the gamma ray intensity Nl when the material space is empty (the material level is L), when actually measuring The measured gamma ray intensity is N, and the material level at this time is calculated according to the calculation formula h=L+ (HL) * (N-Nl) I (Nh-Nl).

(b) Calculate the curve fitting, measure the two gamma ray intensity values of the material full and the material empty, change the material level multiple times, determine the material level value by the mobile positioning method, and measure the gamma corresponding to the material level. The intensity of the ray is obtained, and the corresponding points of the plurality of material levels and the gamma ray intensity including the full material and the material empty are obtained, and the three curves are used to fit the points, and the relationship between the gamma ray intensity and the material level is obtained, and the actual measurement time is obtained. Calculate the corresponding level by using the measured gamma ray intensity value and the relationship curve.

The method uses a reference method instead of the direct method and includes the following steps:

(a) In the vicinity of the environmental radiation near the container to be tested, select a similar container that can be used to determine the material level, and install the continuous passive nuclear level gauge in the measurement position with the container to be tested. Similar location

(b) Measure the gamma ray intensities Nh and Nl at the full and empty, as the gamma ray intensities Nh and Nl at the actual container and at the material empty.

(c) Install the continuous passive nuclear level gauge back to the selected position of the container to be tested, actually measure the gamma ray intensity N, and use the material space and material full ray intensity Nh and Nl just determined, according to the algorithm Level h = L + (HL) * (N-Nl) I (Nh-Nl).

The push algorithm is applicable to the situation that the two states of the filled container and the complete material empty can be determined, including the case where the specific intermediate material level cannot be determined, and the corresponding relationship between the gamma ray intensity and the material level is obtained. The reference method is applicable to all situations, including the inability to determine the actual level, and the determination of the full and empty state of the container under test.

The material level curve in the push algorithm and the reference method is a relatively thick curve, and each material level corresponds to a gamma ray intensity range; each measured gamma ray intensity also corresponds to a material level on the curve. Range, the range is the measurement accuracy of the continuous passive nuclear level gauge; the moving positioning method used in the curve fitting in the push algorithm is in a certain level state, from top to bottom or from Moving the continuous passive nuclear level gauge down and up, simultaneously measuring the intensity of the gamma ray, and obtaining a set of changed data. The continuous passive nuclear level corresponding to the largest difference between two adjacent data in the set of data The measured position of the meter is the actual level. Compared with the prior art, the present invention makes up for the gap of the prior art, and provides a method for determining the relationship between the material level and the gamma ray intensity of the continuous passive nuclear level gauge, which provides a solid foundation for accurately determining the material level. The invention proposes a direct method, a fitting push algorithm and a reference method, which can replace each other according to the actual measurement situation, which not only increases the selectivity of the user according to the actual measurement situation, but also can be used as a test method to improve the reliability of the data. degree.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram showing the internal hardware structure of a passive nuclear level gauge according to the present invention; FIG. 2 is a schematic diagram of the application of a passive nuclear level gauge according to the present invention; Bit diagram; Figure 1. Material 2. Container to be tested 3. Passive nuclear level gauge 4. Passive nuclear level gauge bracket [Detailed Description] The present invention will be further described with reference to the accompanying drawings, which is specialized in the field. The technician is OK To achieve. The method of the present invention is proposed to be applied to a continuous level gauge. It is desirable to continuously output an accurate level signal as the height of the material changes. The basic design of the design is: Continually install a sensitivity point at a determined measurement point. Passive nuclear level gauge, measure the intensity of gamma ray in a determined response time, determine the relationship between the measured gamma ray intensity and the level, and output the measured material according to the actual measured gamma ray intensity value. Bit.

The implementation of the direct method proposed by the present invention should first determine the material level in combination with other methods. The method is not limited to the moving method and the tapping method. According to the measurement accuracy requirement, the gamma ray intensity range corresponding to different material positions is repeatedly measured, and the continuous type is recorded. The intensity of the gamma ray measured by the source nuclear level gauge and its range of variation, thereby obtaining a point on the level curve, and then using various methods to change the level, repeating the above steps, and then obtaining the level curve. Another point, repeated this way, will get a lot of points. By connecting these points together, you can get the range of gamma ray intensity corresponding to different material heights. In fact, what is obtained is a relatively "coarse" material level curve corresponding to one gamma ray intensity range for each material level and one gamma ray intensity value corresponding to one material level range. Try to find enough points to make the connected curve smooth. The measured range of the gamma ray intensity corresponds to the accuracy requirement of the continuous passive nuclear level gauge. The fill level is then determined based on the actual measured gamma ray intensity. The method provided by the invention is applied to a continuous fly ash level gauge, and the level of the ash hopper of the electrostatic precipitator or the bag filter is measured. The hopper of the electric precipitator or the bag filter is used as shown in FIG. 2 Pyramid steel plate structure, height 5-8 meters, inclination angle 60 degrees, externally provided with 20-40cm thick insulation material and color steel plate for protection of thermal insulation material, the internal measured material is the temperature formed after pulverized coal combustion is 135-45CTC Fly ash, in view of the temperature, viscosity and ash impact of fly ash and its strong gamma radioactivity, it is highly desirable to employ the method described herein for ash ash monitoring. The passive nuclear level gauge used in the embodiment mainly includes as shown in FIG. 1 : (1) gamma ray detection The Nal scintillation detector is used to measure the gamma ray intensity of the environment in which the material to be tested and the container to be tested are located; (2) a signal processing module for processing the collected gamma ray intensity signal, which is pre-set according to software The fixed switch point sends out an alarm signal, cancels the alarm signal, or outputs an electronic circuit of the continuous material level signal according to the relationship between the gamma ray intensity and the material level obtained in advance; (3) the material level signal output module for the signal processing module The output alarm signal, alarm release signal, and output signal electronic circuit can be light, sound, I/O port, relay, analog output circuit, communication interface, etc.; (4) Auxiliary module, including mounting bracket, improvement Signal-to-noise ratio ray shielding device, cable connector, antenna, handheld device for setting switching point or gamma ray intensity and material level relationship parameter, communication device for exchanging information between passive nuclear level gauges (5) software for controlling the gamma detector, processing the gamma signal and outputting the alarm signal, releasing the alarm signal , Or a continuous set of all relevant material code signal, or interactive communication to achieve like functionality. The direct measurement method is as follows:

(a) Install a continuous fly ash level gauge at 3/4 of the hopper height so that the direction of detection of the continuous fly ash level gauge is aligned with the hopper and begins to measure gamma ray intensity;

(b) Change the material level, measure and confirm the material level with other material level measuring equipment, record the gamma ray intensity measured by the continuous passive nuclear level meter and its variation range when the reliability is 99%. a line segment on the level curve;

(c) Repeat step (b) until there is sufficient accuracy of the data, usually more than 50 times;

(d) Connect the obtained line segments to obtain the change trend of the gamma ray intensity corresponding to different material levels, that is, the material level curve. According to the material level curve, each gamma ray intensity value corresponds to a material level range, and the cover range is measured. Accuracy

(e) The current gray level range is obtained based on the measured gamma ray intensity N and the above-described fill level curve. Since it is difficult to confirm the material level, but it can be confirmed that the two states of the material and the material are empty, the push is adopted. (a) Install the continuous fly ash level gauge at the 3/4 position of the hopper height so that the detection direction of the continuous fly ash level gauge is aligned with the hopper and begins to measure the gamma ray intensity;

(b) When the hopper is completely empty (gray is L), the measured gamma ray intensity N1 is measured;

(c) When it is empirically confirmed that the hopper is full (gray position H), the gamma ray intensity Nh is measured;

(d) In the actual measurement, the relationship between the measured gamma ray intensity N and the gray position h at this time: h=L+ (HL) * (N-Nl) I (Nh-Nl), and input continuous flight Ash level gauge;

(e) The current gray level range is obtained based on the measured gamma ray intensity N and the above-described fill level curve. Sometimes, the full value of the material is more difficult to obtain. The reference method is used to measure the full value of the material, and then the algorithm is used. The steps are as follows:

(a) Install the continuous fly ash level gauge at the 3/4 position of the hopper height so that the detection direction of the continuous fly ash level gauge is aligned with the ash hopper;

(b) When the hopper is completely empty (level L), the measured gamma ray intensity N1;

(c) Take the continuous fly ash level gauge down, at the same height below the installation location, at the same distance from the hopper, against the ash bucket. The gray position is judged by the moving positioning method, and after confirming that the gray level is more than half, the area with the strongest gamma ray intensity is found in the lower half of the ash bucket, and the strongest gamma ray intensity is approximated as the full gamma ray intensity Nh. _;

(d) Install the continuous fly ash level gauge back to the installation position, and measure the relationship between the measured gamma ray intensity N and the ash h at this time: h=L+ (HL) * (N-N1) / (Nh- Nl), and input continuous fly ash level gauge;

(e) The continuous fly ash level gauge is at the installation position, and the ash position 1 is obtained based on the measured gamma ray intensity N and the above relationship formula. According to the above method, the material level curve shown in Fig. 3 is obtained. As the height of the material level increases, the gamma ray radiation intensity increases, and each material level H corresponds to a gamma ray intensity range (A1, A2). When measuring, each time a gamma ray intensity value A is measured, it corresponds to a range of material levels (H1, H2), which is the measurement accuracy. The direct method, the fitting push algorithm and the reference method can be mutually replaced according to the actual measurement conditions, and can also be used as a test method to improve the reliability of the data.

Claims

A method for determining a fill level curve in a continuous passive nuclear level gauge, comprising a measuring device and a computing module, characterized in that the method employs a direct method comprising the steps of:

(b) Record the intensity of the gamma ray measured by the continuous passive nuclear level gauge and its range of variation at any known level within the measurement range to obtain a line segment on the level of the fill level and the gamma ray intensity ;

(c) Change the level of the material according to the required measurement accuracy, record the intensity of the gamma ray measured by the continuous passive nuclear level gauge and its range of variation, and obtain another line segment on the level of the level and the gamma ray intensity plane;

(d) repeat step (c);

(e) connecting the maximum point of the obtained line segment, and then connecting the minimum point of the obtained line segment to obtain a change trend of the gamma ray intensity corresponding to different material levels, that is, a relatively thick material level curve;

2. A method of determining a fill level curve in a continuous passive nuclear level gauge according to claim 1 wherein the method employs a push algorithm instead of a direct method comprising the following steps:

(a) Linear fitting estimation, measuring the gamma ray intensity Nh when the material is full (feed level H) _; when the material space is empty (level L), the gamma ray intensity Nl is measured, when actually measuring The measured gamma ray intensity is N, and the material level at this time is calculated according to the calculation formula h=L+ (HL) * (N-Nl) I (Nh-Nl);

(b) Calculate the curve fitting, measure the two gamma ray intensity values of the material full and the material empty, change the material level multiple times, determine the material level value by the mobile positioning method, and measure the gamma corresponding to the material level. The ray intensity is obtained, and the corresponding points of the plurality of material levels and the gamma ray intensity including the full material and the material empty are obtained, and the three curves are used to fit the points, and the relationship between the gamma ray intensity and the material level is obtained, and the actual measurement time is obtained. Calculate the corresponding level by using the measured gamma ray intensity value and the relationship curve.

3. A method of determining a fill level curve in a continuous passive nuclear level gauge according to claim 1, wherein the method uses a reference method instead of the direct method, comprising the steps of: (a) In the vicinity of the environmental radiation near the container to be tested, select a similar container that can be used to determine the material level, and install the continuous passive nuclear level gauge in the measurement position with the container to be tested. Similar location

(b) Measure the gamma ray intensities Nh and Nl when the material is full and empty, as the gamma ray intensities Nh and N1 when the material is actually filled and empty;

(c) Install the continuous passive nuclear level gauge back to the selected position of the container under test, actually measure the gamma ray intensity N, and use the material space and material full ray intensity Nh and Nl just determined, according to the algorithm Level h = L + (HL) * (N-Nl) I (Nh-Nl).

4. A method for determining a fill level curve in a continuous passive nuclear level gauge according to claim 1 or 2, wherein the push algorithm is adapted to determine that the measured container is full and completely empty. In the case of two states, including the case where the specific intermediate level cannot be determined, the correspondence between the gamma ray intensity and the material level is obtained.

5. A method of determining a fill level curve in a continuous passive nuclear level gauge according to claim 1 or 3, wherein said reference method is applicable to all situations, including the inability to determine the actual fill level, It is not possible to determine the condition in which the measured container is full and empty.

6. A method of determining a fill level curve in a continuous passive nuclear level gauge according to claim 1 or 2 or 3, wherein:

(a) The fill level curve is a relatively thick curve, each level corresponding to a gamma ray intensity range;

(b) Each measured gamma ray intensity also corresponds to a fill level on this curve, the range

7 . The mobile positioning method used in the curve fitting estimation method for determining a material level curve in a continuous passive nuclear material level meter according to claim 2 , wherein: (a) moving the continuous passive nuclear level gauge from top to bottom or from bottom to top at a certain level, and simultaneously measuring the intensity of the gamma ray to obtain a set of varying data;

(b) The measurement position of the continuous passive nuclear level gauge corresponding to the largest difference between two adjacent data in the set of data is the actual level.