CN112229762A

CN112229762A - Method for measuring density of fluid in pipeline and density measuring and mounting structure

Info

Publication number: CN112229762A
Application number: CN202011251801.7A
Authority: CN
Inventors: 王侃; 黄立立; 周宗伟; 王硕
Original assignee: Nanjing Yugong Intelligent Technology Co ltd
Current assignee: Nanjing Yugong Intelligent Technology Co ltd
Priority date: 2020-11-06
Filing date: 2020-11-11
Publication date: 2021-01-15

Abstract

The invention discloses a method for measuring density of fluid in a pipeline and a density measuring and mounting structure. When the density meter is used for measuring the density of fluid in a measured pipeline, the radioactive source is arranged in the measured pipeline, so that gamma rays radiated by the radioactive source in the measured pipeline can be detected by a probe arranged outside the pipeline, and the density of the fluid or slurry flowing through the measured pipeline is measured. The density measurement mounting structure is a mounting structure that matches the measurement method. Compared with the traditional densimeter measuring method, the measuring method can measure the pipeline with larger diameter. The source protection tube for arranging the radioactive source is obliquely arranged along the flowing direction of the fluid, so that the flow resistance of the source protection tube to the fluid is reduced, and the scouring of the flowing fluid to the source protection tube can be reduced.

Description

Method for measuring density of fluid in pipeline and density measuring and mounting structure

Technical Field

The present invention relates to densitometers, and more particularly to a gamma-ray densitometer for measuring the head density of a stream in a pipe.

Background

A gamma-ray densitometer is a device for measuring the density of a substance made according to the property that the capacity of the substance through which gamma rays pass is inversely proportional to the density of the substance. Gamma rays do not need to contact matter as they pass through it. Gamma-ray densitometers are thus a non-contact measurement device and are therefore widely used to measure fluid or slurry density in pipes. When the gamma-ray densitometer is used for measuring the density of fluid or slurry in a pipeline, a gamma-ray source and a probe are respectively arranged at the opposite sides of the pipeline, so that gamma rays emitted by the gamma-ray source can penetrate through the pipeline and be detected by the probe at the opposite side. The probe is connected with a calculating part. The calculation part calculates the density of the fluid or slurry in the pipeline according to the gamma ray count or the gamma ray density detected by the probe and the calibration contrast.

The above-described measurement of fluid or slurry density in a pipe by means of a gamma-ray densitometer has substantial drawbacks. First, the gamma rays emitted from the gamma ray source need to pass through the air twice and the tube wall twice, in addition to the material to be measured. Gamma rays pass through air and tube walls with attenuation which is inherent in the material being measured, so that the gamma rays emitted by the gamma ray source are wasted in large quantities. Secondly, when the diameter of the pipeline is relatively thick, the gamma rays cannot penetrate to the opposite side, and at the moment, all the gamma rays are absorbed, so that the probes on the opposite side cannot detect the gamma rays. This also means that this measurement method cannot measure large diameter pipes. Thirdly, in the prior art, the radioactive source used in the gamma-ray densitometer is cesium-137. This is because cesium-137 is present in large amounts in radioactive waste liquid from nuclear industry and is relatively easily available. The cesium-137 beta decays and then is converted into barium-137, and the barium-137 homoenergetic transition decays to emit gamma rays with the energy of 0.6617 MeV. On the one hand, the cesium-137 is a radioactive substance with great harm and is a dangerous article regulated by the state. For the user, there is a safety problem in use, and for the manufacturer, the production and sale need to be approved, which is troublesome in procedure. On the other hand, gamma rays with energy of 0.6617MeV have smaller energy than other sources of gamma rays, so the penetration capacity also appears slightly smaller, which further highlights the problem of inability to measure large diameter pipes.

Disclosure of Invention

The problems to be solved by the invention are as follows: in the prior art, when a gamma ray densitometer measures the density of fluid or slurry in a pipeline, the problems that gamma rays emitted by a gamma ray source are wasted greatly and a large-diameter pipeline cannot be measured exist.

In order to solve the problems, the invention adopts the following scheme:

according to the method for measuring the density of the fluid in the pipeline, when the density meter is used for measuring the density or concentration of the fluid or slurry in the pipeline to be measured, the radioactive source is arranged in the pipeline to be measured, so that gamma rays radiated by the radioactive source in the pipeline to be measured can be detected by the probe arranged outside the pipeline, and the density or concentration of the fluid or slurry flowing through the pipeline to be measured can be measured.

Further, according to the method for measuring the density of the fluid in the pipeline, the radioactive material serving as the radioactive source is an exempted source.

Further, according to the method for measuring the density of the fluid in the pipeline, the exemption source adopts sodium-22.

Further, according to the method for measuring the density of the fluid in the pipeline, the radioactive source is arranged in the pipeline to be measured through a source protection pipe inserted into the pipeline to be measured; the source protection pipe is inclined along the flowing direction of fluid or slurry in the pipeline to be detected.

Further, according to the method for measuring the density of the fluid in the pipeline, the axial inclined included angle between the source protection pipe and the pipeline to be measured is 20-60 degrees.

Further, according to the method for measuring the density of the fluid in the pipeline, the radioactive source is arranged in the area, which is not more than half of the inner radius of the measured pipeline away from the center of the measured pipeline, in the measured pipeline.

Further, according to the method for measuring the density of the fluid in the pipeline, the probe and the radioactive source form a certain included angle relative to the center of the pipeline to be measured.

The invention discloses a density measurement mounting structure, which comprises a radioactive source, a densimeter and a radioactive source pipe mounting device; the densimeter comprises a probe and a calculating part; the probe is arranged outside the target pipe; the probe is connected with the calculating part; the radioactive source is arranged in the target pipe through the radioactive source pipe installation device, so that gamma rays radiated from the radioactive source in the target pipe are detected by the probe arranged outside the pipe, and the calculating part obtains the gamma ray count or density detected by the probe through the connected probe and calculates the density or concentration of the fluid or slurry flowing through the target pipe.

Further, according to the density measurement mounting structure of the present invention, an exempt source is used as the radioactive material of the radioactive source.

Further, according to the density measurement mounting structure of the present invention, the exemption source employs sodium-22.

Further, according to the density measurement mounting structure of the present invention, the radiation source is disposed by the radiation source tube inside mounting device in an area within the target tube not more than a half of an inner radius of the target tube from a center of the target tube.

Further, according to the density measurement mounting structure of the present invention, the probe and the radiation source have an angle with respect to the center of the target tube.

Further, according to the density measurement mounting structure of the present invention, the radioactive source tube interior mounting device includes a mounting tube, a source protection tube, and a source rod; the mounting pipe is arranged on the pipe wall of the target pipe, is positioned outside the target pipe and is communicated with the target pipe; one end of the source protection tube is sealed, and the other end is opened; the source protection pipe penetrates through the installation pipe, one end of the source protection pipe is arranged in the target pipe, and the other end of the source protection pipe is arranged outside the target pipe; one end of the source protection tube in the target tube is sealed, and one end outside the target tube is opened; the source protection pipe penetrating through the installation pipe is fixed with the installation pipe through a first fixing mechanism; the radioactive material as the radioactive source is arranged at the tail end of the source rod; the source rod is inserted into the source protection tube through an opening at the opening end of the source protection tube, so that the radioactive material arranged at the tail end of the source rod is pushed to the sealing end of the source protection tube, and the radioactive material serving as a radioactive source is arranged in the target tube; the source rod is fixed with the source protection tube through a second fixing mechanism.

Further, according to the density measurement mounting structure of the present invention, the first fixing mechanism includes a first flange provided at the end of the mounting pipe and a second flange provided at the open end of the source pipe; and the second flange and the first flange are fastened through bolts.

Further, according to the density measurement mounting structure of the present invention, the radioactive source tube mounting device further includes a gasket disposed between the first flange and the second flange.

Further, according to the density measurement mounting structure of the present invention, the second fixing mechanism includes an internal thread provided in the source protection pipe and an external thread provided on the source rod; the source rod external thread is matched with the source protection pipe internal thread, so that the source rod is arranged in the source protection pipe in a thread matching mode.

Further, according to the density measurement mounting structure of the present invention, the mounting pipe is inclined to the target pipe such that the source pipe is inclined to the target pipe and the source pipe is inclined in the flow direction of the fluid or slurry in the target pipe.

Further, according to the density measurement mounting structure, an axial inclined included angle between the source protection pipe and the target pipe is 20-60 degrees.

Further, according to the density measurement mounting structure of the present invention, the source pipe and the target pipe intersect in the axial center.

Further, according to the density measurement mounting structure of the present invention, the target pipe is a pipe under test.

Further, the density measurement mounting structure according to the present invention further includes an insertion pipe serving as a target pipe; the inserting pipe is used for being inserted on the measured pipeline and comprises an abutting flange for abutting joint with the measured pipeline; the inserting pipe is connected with the mounting pipe in a welding mode.

The invention has the following technical effects:

1. the gamma ray emitted by the radioactive source directly passes through the fluid or the slurry to be measured from the pipe and then is emitted to the probe after passing through the pipe wall of the pipeline to be measured, and does not need to pass through the air and the pipe wall twice, so that the waste of the gamma ray is reduced. On the other hand, gamma rays do not pass through the entire pipe under test. Thus, the densitometer of the present invention is capable of measuring larger diameter pipes than conventional densitometers.

2. Compared with cesium-137 and other materials, the radioactive material meets the environmental safety standard, has no national regulation, and saves the examination and approval procedures for production and sale. And at the same time no special protection is required.

3. The source protection tube for arranging the radioactive source is obliquely arranged along the flowing direction of the fluid, so that the flow resistance of the source protection tube to the fluid is reduced, and the scouring of the flowing fluid to the source protection tube can be reduced.

Drawings

FIG. 1 is a schematic view of an installation configuration for density measurement of a pipe fluid according to an embodiment of the present invention.

Fig. 2 is a schematic structural diagram of an embodiment of the radioactive source in-tube installation device of the invention.

Fig. 3 is an enlarged schematic view of the dotted circle portion of fig. 1 according to the present invention.

FIG. 4 is a schematic structural diagram of another embodiment of a density measurement mounting structure according to an embodiment of the present invention when a pipe fluid is used for measuring density.

Wherein the content of the first and second substances,

100 is a radioactive source, 200 is a probe, 300 is a calculating part, and 400 is a radioactive source tube mounting device;

1 is an installation pipe, 11 is a first flange, and 12 is a first installation hole;

2 is a source protection pipe, 21 is a second flange, 22 is an internal thread, 23 is a second mounting hole, 28 is an opening end, and 29 is a sealing end;

3 is the source rod, 31 is the external thread;

4 is a gasket, 41 is a third mounting hole;

5 is a radioactive material;

6 is a plug pipe, 61 is the pipe wall of the plug pipe, 62 is a butt flange, 621 is a butt mounting hole;

9 is the target vessel, 91 is the vessel wall of the target vessel, 99 is the lumen of the target vessel;

a is an axial inclined included angle between the source protection tube and the target tube;

the dotted circle D is an area no more than half of the inner radius of the target tube from the center of the target tube;

arrow R indicates the direction of gamma ray emission from the source;

arrow V indicates the flow direction of the fluid or slurry in the pipe under test;

t is the radial direction of the probe, P is the radial direction of the radioactive source;

and B is the included angle between the probe and the radioactive source relative to the center of the target tube.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings.

Implement one

Fig. 1 illustrates a method of measuring fluid density in a pipe and a density measurement mounting structure corresponding to the method. The densitometer mounting structure includes a radioactive source 100, a densitometer, and a radioactive source tube mounting apparatus 400. Wherein the densitometer includes a probe 200 and a calculating portion 300. The probe 200 is used to detect gamma rays emitted from the radiation source 100 and passing through a substance to be measured. The calculating unit 300 is used for calculating the density of the measured substance by connecting the probe 200 and acquiring the gamma ray count or density detected by the probe 200. The radioactive source 100 is disposed in the pipe to be measured by the radioactive source tube inside-mounting device 400. In the present embodiment, the pipe to be measured is exemplified by the target pipe 9. Specifically, the radiation source 100 is disposed in the lumen 99 of the target tube 9 through the source tube 2 of the source tube inside mount 400. The probe 200 is disposed outside the target tube 9 and aligned with the centers of the radiation source 100 and the target tube 9, so that gamma rays radiated from the radiation source 100 inside the target tube 9 can be detected by the probe 200 disposed outside the tube. The probe 200 is connected to the calculating part 300. The calculation section 300 calculates the density or concentration of the fluid or slurry flowing through the target pipe 9 by acquiring the gamma ray count or density detected by the probe 200 through the connected probe 200. In this embodiment, the measured substance is a fluid or slurry in the target pipe 9 or the measured pipe. As will be understood by those skilled in the art, after the calculating part 300 calculates the density of the fluid or slurry, the calculating part 300 can easily calculate the corresponding density from the calculated density according to the correspondence between the density and the fluid or slurry concentration.

The density measurement mounting structure is particularly applied to a method for measuring the density of fluid in a pipeline, namely, when the density measurement mounting structure is used for measuring the density or concentration of fluid or slurry in a pipeline to be measured, a radioactive source is arranged in the pipeline to be measured, so that gamma rays radiated by the radioactive source in the pipeline to be measured can be detected by a probe arranged outside the pipeline, and the density of the fluid or the slurry flowing through the pipeline to be measured is measured. As can be seen from figure 1, the gamma ray emitted by the radioactive source 100 directly passes through the fluid or slurry to be measured from the tube and then is emitted to the probe 200 after passing through the wall of the target tube 9, and does not need to pass through the air and the wall twice, thereby reducing the waste of gamma ray. On the other hand, gamma rays do not pass through the entire conduit of the target pipe 9. Therefore, this density measurement installation structure of the present embodiment can measure a pipe of a larger diameter than conventional measurement.

In this embodiment, the source protection pipe 2 is inclined along the flow direction V of the fluid or slurry in the target pipe 9, so that the flow resistance of the source protection pipe 2 to the fluid or slurry in the target pipe 9 can be reduced, and the scouring effect of the flowing fluid or slurry on the source protection pipe 2 can be reduced. In the configuration illustrated in fig. 1, the centers of the probe 200, the radiation source 100 and the target tube 9 are aligned, and when the probe 200 and the radiation source 100 are at an angle of 0 with respect to the center of the target tube 9, the fluid or slurry to be detected is located behind the source-protective tube 2 where the radiation source 100 is installed and is blocked by the source-protective tube 2, and thus the detected density or concentration may not be accurate. For this purpose, the probe 200 may also be provided elsewhere, for example with reference to fig. 4. In the configuration illustrated in figure 4, the probe 200 and the source 100 are at an angle B with respect to the centre of the target tube 9, the angle B being different from 0, whereby the fluid or slurry being detected avoids the obstruction of the source tube 2.

It should be noted that there may be instances where the density of the portions is not the same due to insufficient mixing of the fluid slurry within the pipe. For this purpose, the radiation source 100 is preferably arranged within the target tube 9 in an area which is not more than half the inner radius of the target tube 9 from the center of the target tube 9, as is indicated by the dashed circle D in fig. 4. The inner radius here means half of the inner diameter. That is, the radiation source tube inside-mounting device 400 is such that the radiation source 100 is disposed inside the target tube 9 within an area not more than a half of the inner radius of the target tube 9 from the center of the target tube 9, or the radiation source 100 is disposed inside the target tube 9 within an area not more than a half of the inner radius of the target tube 9 from the center of the target tube 9 by the radiation source tube inside-mounting device 400

It should also be noted that in practical measurement applications, the target tube 9 may be a pipe to be actually measured, or may be a plug tube 6 specially configured for installing the radiation source 100 in the pipe. Referring to fig. 2, the bayonet tube 6 includes abutment flanges 62 provided at both ends of the tube body. The butt flange 62 is used for butt joint with a pipe to be tested and is provided with a butt joint mounting hole 621 for bolt fixing. When the insertion tube 6 is installed in actual use, the radioactive source 100 is firstly arranged in the insertion tube 6 through the radioactive source tube installation device 400, then the pipeline to be detected is directly cut off, and then the insertion tube 6 is connected between the two sections of the pipeline to be detected which are cut off. Since the radiation source 100 can be pre-mounted on the insertion tube 6. Therefore, when the radioactive source 100 is installed in the field to the measured pipeline, the actual field assembly only needs to cut the measured pipeline and then connect the splicing pipe 6 between the two sections of the cut measured pipeline.

It should also be noted that the radiation source 100 is preferably an exempt source. Exempt sources refer to radioactive materials such as sodium-22 or cobalt-60 that do not exceed environmental safety standards in their radioactive strength. Sodium-22 is preferably employed in the present invention. If the radiation source 100 does not adopt an exemption source, then under the structure of the invention, safety protection measures such as a protective cover and the like are required to be arranged, and the exemption source is adopted, and because the exemption source is safe to a human body, the protective cover is not required to be arranged particularly.

Example two

This embodiment illustrates the structure of a radioactive source tube inside mounting device 400. It should be noted that the radioactive source tube installation device in the first embodiment has many specific embodiments. The present embodiment is merely one example configuration thereof.

In this embodiment, the structure of the radioactive source tube installation device 400 is shown in fig. 1, 2 and 3, and the device is used for installing the radioactive source 100 in the target tube 9 and comprises an installation tube 1, a source protection tube 2 and a source rod 3.

The installation tube 1 is used for being fixedly connected and communicated with the target tube 9. Specifically, in the installation, first, an installation hole is opened in the pipe wall 91 of the target pipe 9, and then the installation pipe 1 is inserted into the installation hole and welded to the target pipe 9. That is, specifically, the mounting tube 1 is disposed on the tube wall 91 of the target tube 9, outside the target tube 9, in communication with the target tube 9, and is preferably welded to the tube wall 91 of the target tube 9.

The source pipe 2 passes through the installation pipe 1. The source tube 2, which passes through the mounting tube 1, has one end inside the target tube 9 and the other end outside the target tube 9. The source protection tube 2 is positioned at one end inside the target tube 9 and is sealed, namely a sealed end 29; the target tube 9 is open at one end and is an open end 28. A first fixing mechanism which is mutually matched is arranged between the source protection pipe 2 and the installation pipe 1, and the source protection pipe 2 which penetrates through the installation pipe 1 is fixed in the installation pipe 1 through the first fixing mechanism.

In this embodiment, the first fixing means comprises a first flange 11 provided at the end of the mounting tube 1 and a second flange 21 provided at the open end 28 of the source tube 2. The second flange 21 and the first flange 11 can be fastened by bolts. Specifically, the first flange 11 is provided with a plurality of first mounting holes 12, and the second flange 21 is provided with a plurality of second mounting holes 23. The second mounting holes 23 correspond to the first mounting holes 12, respectively. Thus, when the second flange 21 and the first flange 11 are closely fitted and the second mounting hole 23 and the first mounting hole 12 are aligned, bolt fixing is performed by bolts passing through the first mounting hole 12 and the second mounting hole 23.

Further, to avoid that fluid or slurry in the target pipe 9 flows out through the gap between the installation pipe 1 and the source pipe 2. The apparatus further comprises a sealing mechanism between the source tube 2 and the mounting tube 1. In the present embodiment, the sealing mechanism is realized by the gasket 4. The gasket 4 is disposed between the second flange 21 and the first flange 11. The gasket 4 is provided with a plurality of third mounting holes 41. The third mounting holes 41 correspond to the second mounting holes 23 and the first mounting holes 12, respectively. When mounted, the gasket 4 is disposed between the second flange 21 and the first flange 11, and when the third mounting hole 41, the second mounting hole 23, and the first mounting hole 12 are aligned, bolt-fixing is performed by bolts passing through the first mounting hole 12, the second mounting hole 23, and the third mounting hole 41.

It should be noted that the first fixing mechanism described above in this embodiment is merely an exemplary embodiment. In practice, there may be many structures, such as those that also use a threaded fit with an additional sealing ring for sealing, as will be familiar to those skilled in the art.

The source rod 3 is provided at its distal end with a connection for the radioactive material 5 and is provided with the radioactive material 5 through the connection. The source rod 3 is inserted into the source tube 2 through the opening of the open end 28 of the source tube 2 so that the radioactive material 5 disposed at the distal end of the source rod 3 is pushed to the sealed end 29 of the source tube 2, and the radioactive material 5 as the radioactive source 100 is disposed in the target tube 9. A second fixing mechanism which is matched with the source rod 3 is arranged between the source protection tube 2 and the source rod. The source rod 3 is fixed with the source protection tube 2 through a second fixing mechanism.

In this embodiment, the second fixing means comprise an internal thread 22 provided in the source tube 2 and an external thread 23 provided on the source rod 3. The external thread 23 of the source rod 3 and the internal thread 22 of the source tube 2 cooperate such that the source rod 3 can be arranged in the source tube 2 by means of a thread fit. It should be noted that the second fixing mechanism of the present embodiment is merely an exemplary embodiment. In actual practice, a wide variety of configurations are possible. For example, the fixing device can be fixed by a snap, which is familiar to those skilled in the art. In this embodiment, the second fixing mechanism is screwed to facilitate the replacement of the radioactive material 5 when the radioactive material 5 is exhausted.

In consideration of the scouring effect of the fluid or slurry flowing in the target pipe 9 on the source pipe 2, the source pipe 2 is disposed obliquely in the present embodiment. Specifically, the installation pipe 1 is inclined with respect to the target pipe 9, whereby the source pipe 2 inserted into the installation pipe 1 is inclined with respect to the target pipe 9, and the source pipe 2 is inclined in the flow direction V of the fluid or slurry in the target pipe 9. Generally, the source pipe 2 is disposed toward the center of the target pipe 9, that is, the axial center of the source pipe 2 and the axial center of the target pipe 9 intersect. The source tube 2 is inclined to the target tube 9, i.e. there is an axial inclination angle a between the axial direction of the source tube 2 and the axial direction of the target tube 9. The axial inclined included angle A is usually 20-60 degrees, and preferably 30-50 degrees. The source protection pipe 2 is inclined along the flowing direction V of the fluid or the slurry in the target pipe 9, so that the flowing resistance of the source protection pipe 2 to the fluid or the slurry in the target pipe 9 can be reduced, and the scouring effect of the flowing fluid or the slurry on the source protection pipe 2 is reduced.

The connection mechanism provided at the end of the source rod 3 is typically a screw-fit structure. In this embodiment, the radioactive material 5 is a commercially available member containing sodium-22, and is a cylindrical body made of sodium-22-containing stainless steel having a diameter of 8mm and a length of 10mm, and is provided with a threaded connection portion. The distal end of the source rod 3 is connected to the radioactive material 5 by means of a screw-thread fit.

Note that the target pipe 9 according to the above configuration serves as a pipe to be measured, and the installation pipe 1 is welded to the pipe to be measured. It will be appreciated by those skilled in the art that the aforementioned bayonet tube 6, which is the target tube 9, may also be part of the radioactive source tube mounting apparatus 400. At this time, the insertion pipe 6 and the mounting pipe 1 are welded and connected integrally. In this embodiment, the mounting pipe 1 and the target pipe 9 are welded and connected to each other as an integral component, and the mounting pipe 1 is a part of the integral component. Therefore, during actual installation, only the insertion tube 6 needs to be installed on the measured pipeline, then the source protection tube 2 is installed on the installation tube 1, and finally the radioactive material 5 is arranged in the insertion tube 6 through the source rod 3. Therefore, the radioactive material 5 is very convenient to replace, and when the radioactive material 5 is replaced, the source rod 3 is only required to be taken out of the source protection tube 2, then the radioactive material 5 at the tail end of the source rod 3 is replaced, and then the source rod 3 with the radioactive material 5 replaced is inserted into the source protection tube 2 again.

In addition, it should be noted that, in the first and second embodiments, the target pipe 9 is a pipe through which fluid or slurry passes, and may be a pipe to be measured, or may be a plug pipe connected to the pipe to be measured. The person skilled in the art understands that the target pipe 9 may also be a container for receiving a fluid or slurry, such as a reaction vessel or the like. It is noted that the source pipe 2 need not be inclined since the fluid or slurry in the container does not flow.

Claims

1. A method for measuring the density of fluid in a pipeline is characterized in that when a densimeter is used for measuring the density or concentration of the fluid or slurry in the pipeline to be measured, a radioactive source is arranged in the pipeline to be measured, so that gamma rays radiated by the radioactive source in the pipeline to be measured can be detected by a probe arranged outside the pipeline to measure the density or concentration of the fluid or slurry flowing through the pipeline to be measured.

2. The method of fluid density measurement in a pipe of claim 1, wherein the radioactive material as the source of radiation is an exempt source.

3. A method of fluid density measurement in a pipe as claimed in claim 2 wherein the source of exemption is sodium-22.

4. The method for measuring fluid density in a pipe as claimed in claim 1, wherein said radiation source is disposed in the pipe under test through a source-protecting tube inserted into the pipe under test; the source protection pipe is inclined along the flowing direction of fluid or slurry in the pipeline to be detected.

5. The method for measuring the density of the fluid in the pipeline as claimed in claim 4, wherein the axial inclined included angle between the source protection pipe and the pipeline to be measured is 20-60 degrees.

6. The method of in-line fluid density measurement according to claim 1, wherein the radiation source is disposed within the pipe under test within an area no more than half of an inner radius of the pipe under test from a center of the pipe under test.

7. The method of claim 1, wherein the probe and the radiation source are angled with respect to the center of the pipe being measured.

8. A density measurement mounting structure is characterized by comprising a radioactive source (100), a densimeter and a radioactive source tube mounting device (400); the densitometer includes a probe (200) and a calculating section (300); the probe (200) is arranged outside the target pipe (91); the probe (200) is connected with the calculating part (300); the radioactive source (100) is arranged in a target pipe (9) through the radioactive source pipe installation device (400), so that gamma rays emitted by the radioactive source (100) from the target pipe (9) are detected by the probe (200) arranged outside the target pipe, and the calculating part (300) obtains the gamma ray count or density detected by the probe (200) through the connected probe (200) and calculates the density or concentration of the fluid or slurry flowing through the target pipe (9).

9. Density-measuring mounting arrangement according to claim 8, characterised in that an exempt source is used as the radioactive material (35) of the radiation source (100).

10. A density measurement mounting arrangement according to claim 9, wherein the exemption source employs sodium-22.

11. Density measuring mounting arrangement according to claim 8, characterised in that the radioactive source (100) is arranged by the radioactive source tube mounting means (400) within the target tube (9) within an area not more than half the inner radius of the target tube (9) from the centre of the target tube (9).

12. Density measuring mounting arrangement according to claim 8, characterised in that the probe (200) and the radiation source (100) are at an angle relative to the centre of the target tube (9).

13. Density measuring mounting arrangement according to claim 8 or 9 or 10 or 11 or 12, wherein said radioactive source tube mounting means (400) comprises a mounting tube (1), a source tube (2) and a source rod (3); the mounting pipe (1) is arranged on the pipe wall of the target pipe (9), is positioned outside the target pipe (9), and is communicated with the target pipe (9); one end of the source protection tube (2) is sealed, and the other end is opened; the source protection pipe (2) penetrates through the installation pipe (1), one end of the source protection pipe is arranged in the target pipe (9), and the other end of the source protection pipe is arranged outside the target pipe (9); one end of the source protection tube (2) in the target tube (9) is sealed, and the other end outside the target tube (9) is opened; the source protection pipe (2) penetrating through the installation pipe (1) is fixed with the installation pipe (1) through a first fixing mechanism; the radioactive material (5) as the radioactive source (100) is arranged at the tail end of the source rod (3); the source rod (3) is inserted into the source protection tube (2) through an opening of an opening end of the source protection tube (2), so that radioactive materials (5) arranged at the tail end of the source rod (3) are pushed to a sealing end of the source protection tube (2), and then the radioactive materials (5) serving as radioactive sources (100) are arranged in a target tube (9); the source rod (3) is fixed with the source protection tube (2) through a second fixing mechanism.

14. A density measurement mounting arrangement according to claim 13, wherein the first fixing means comprises a first flange (11) provided at the end of the mounting tube (1) and a second flange (21) provided at the open end of the source pipe (2); the second flange (21) and the first flange (11) are fastened through bolts.

15. Density measuring mounting arrangement according to claim 14, characterised in that said radioactive source intratubular mounting means (400) further comprises a sealing gasket (4) arranged between the first flange (11) and the second flange (21).

16. A density measuring mounting arrangement according to claim 13, wherein the second fixing means comprises an internal thread provided in the source tube (2) and an external thread provided on the source rod (3); the source rod (3) external thread is matched with the source protection pipe (2) internal thread, so that the source rod (3) is arranged in the source protection pipe (2) in a thread matching mode.

17. A density measuring mounting arrangement according to claim 13, characterised in that the mounting tube (1) is inclined to the target tube (9) such that the source tube (2) is inclined to the target tube (9) and the source tube (2) is inclined in the direction of flow of the fluid or slurry in the target tube (9).

18. The density measurement mounting structure according to claim 17, wherein an axial inclined included angle between the source pipe (2) and the target pipe (9) is 20 to 60 degrees.

19. A density measurement mounting arrangement according to claim 13, wherein the source pipe (2) and the target pipe (9) intersect axially.

20. A density measuring mounting arrangement according to claim 13, wherein the target pipe (9) is a pipe under test.

21. The density measurement mounting structure according to claim 13, further comprising a socket pipe (6) serving as a target pipe (9); the inserting pipe (6) is used for being inserted on a measured pipeline and comprises an abutting flange (62) for abutting with the measured pipeline; the insertion pipe (6) is connected with the installation pipe (1) in a welding mode.