CN214844612U

CN214844612U - Radioactive source pipe mounting device and densimeter thereof

Info

Publication number: CN214844612U
Application number: CN202022588497.7U
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: 2021-11-23
Anticipated expiration: 2030-11-11
Also published as: CN112284970A

Abstract

The utility model discloses a radioactive source intraductal installation device and densimeter thereof. The densimeter arranges the radioactive source in the measured pipeline through the radioactive source in-pipe installation device, so that gamma rays emitted by the radioactive source in the measured pipeline can be detected by the probe arranged outside the pipe, and the density of fluid or slurry flowing through the measured pipeline is measured. Compare in traditional densimeter, the utility model discloses a densimeter can measure the pipeline that the diameter is bigger.

Description

Radioactive source pipe mounting device and densimeter thereof

Technical Field

The utility model relates to a densimeter, in particular to gamma ray densimeter for measuring head density in pipeline.

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 utility model discloses the problem that will solve: 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 above problem, the utility model discloses a scheme as follows:

according to the utility model discloses a radiation source is installation device in pipe, the device are used for setting up the radiation source in the target pipe, make the radiation source is in the gamma ray of the intraductal radiation of target can be detected by the probe that the outside of tubes set up, thereby measure to flow through the fluid of target pipe or the density of slurry.

Further, according to the radioactive source tube mounting device of the utility model, the device also comprises a radioactive source; the radioactive source is an exemption source.

Further, according to the utility model discloses a device for installing in radioactive source tube, the exemption source is sodium-22.

Further, according to the utility model discloses a device for installing in radiation source pipe, the device still makes the radiation source is set up the intraductal distance of target the target pipe center is no longer than in the area of the intraductal half of radius of target.

Furthermore, according to the radioactive source tube inner installation device of the utility model, the device comprises an installation tube, a source protection tube and a source rod; the mounting pipe is used for being fixedly connected and communicated with the target pipe; one end of the source protection tube is sealed, and the other end is opened; a first fixing mechanism which is matched with the source protection pipe is arranged between the source protection pipe and the installation pipe; the first fixing mechanism is used for fixing the source protection pipe penetrating through the installation pipe in the installation pipe, so that the sealing end of the source protection pipe is positioned in the target pipe, and the opening end of the source protection pipe is positioned outside the target pipe; the tail end of the source rod is provided with a connecting mechanism for arranging radioactive materials; a second fixing mechanism which is matched with the source rod is arranged between the source rod and the source protection tube; the second fixing mechanism is used for fixing the source rod inserted into the source protection tube through the opening of the opening end of the source protection tube in 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.

Further, according to the radioactive source tube installation device of the present invention, the first fixing mechanism includes a first flange disposed at the end of the installation tube and a second flange disposed at the opening end of the source protection tube; the second flange and the first flange can be fastened through bolts.

Further, according to the utility model discloses a radiation source is installation device in pipe still including being used for setting up the sealed pad between first flange and second flange.

Further, according to the radioactive source tube installation device of the present invention, the second fixing mechanism includes an internal thread provided in the source protection tube 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 can be arranged in the source protection pipe in a thread matching mode.

Furthermore, the radioactive source tube internal installation device also comprises an inserting tube used as a target tube; 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.

Further, according to the utility model discloses an installation device in radiation source pipe, the installation pipe with target pipe inclines mutually, makes source protecting pipe with target pipe inclines mutually, and source protecting pipe follows the flow direction slope of fluid or slurry in the target pipe.

Further, according to the utility model discloses an installation device in the radiation source pipe, the source protection pipe with the axial tilt contained angle is 20~60 degrees between the target pipe.

Further, according to the utility model discloses a radiation source intraductal installation device, the source protection pipe with the target pipe axle center is crossing.

The densimeter comprises a probe and a calculating part; the probe is used for detecting gamma rays emitted by the radioactive source; the calculating part is used for calculating the density of the measured object by connecting the probe and acquiring the gamma ray count or density detected by the probe; the densimeter also comprises a radioactive source tube installation device; the radioactive source tube-in-tube mounting device is used for arranging the radioactive source in a target tube, so that gamma rays radiated by the radioactive source in the target tube can be detected by the probe arranged outside the target tube, and the calculating part can calculate the density of fluid or slurry flowing through the target tube.

Further, according to the utility model discloses a densimeter, the intraductal installation device of radioactive source is the intraductal installation device of foretell radioactive source.

The technical effects of the utility model are as follows:

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. Therefore, compare in traditional densimeter, the utility model discloses a densimeter can measure the pipeline of bigger diameter.

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 utility model discloses a source pillar sets up along with fluid flow direction slope, reduces the produced flow resistance of source pillar adversary from this, also can reduce the washing away of fluid to source pillar that flows simultaneously.

Drawings

Fig. 1 is a schematic diagram of the mounting structure of the embodiment of the densitometer of the present invention when measuring density of a pipe fluid.

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

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

Fig. 4 is a schematic structural diagram of another embodiment of the densitometer of the present invention when measuring density of a pipe fluid.

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 and 4 illustrate a densitometer including a probe 200, a calculation section 300, and a radioactive source tube installation apparatus 400. 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 in-tube mounting device 400 is used to dispose the radioactive source 100 in the pipe to be measured, so that gamma rays radiated from the radioactive source 100 in the pipe to be measured can be detected by the probe 200 disposed outside the pipe, and the calculating part 300 can calculate the density or concentration of the fluid or slurry flowing through the pipe to be measured. In fig. 1 and 4, the pipe under test is illustrated by a target pipe 9. Which, in measuring the density or concentration of a fluid or slurry flowing through a target tube 9, a radioactive source 100 is disposed within the lumen 99 of the target tube 9 through the source tube 2 in the radioactive source tube interior mounting apparatus 400. The probe 200 is disposed outside the target tube 9, so that gamma rays emitted from the radiation source 100 within 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 calculating unit 300 calculates the density of the measured substance by acquiring the gamma ray count or the 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.

As can be seen from fig. 1 and 4, the gamma rays emitted by the radiation source 100 directly pass through the fluid or slurry to be measured from the pipe and then are emitted to the probe 200 after passing through the pipe wall of the target pipe 9, so that the gamma rays do not need to pass through the air and the pipe wall twice, and the waste of the gamma rays is reduced. On the other hand, gamma rays do not pass through the entire conduit of the target pipe 9. Thus, the densitometer of the present embodiment is capable of measuring larger diameter pipes than conventional measurements.

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 shown in 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. The utility model preferably adopts sodium-22. 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, when installing, the installation tube 1 is disposed on the tube wall 91 of the target tube 9, outside the target tube 9, and is connected to the tube wall 91 of the target tube 9, preferably by welding.

One end of the source protection tube 2 is sealed, and the other end is opened. A first fixing mechanism which is mutually matched is arranged between the source protection tube 2 and the installation tube 1. The first fixing mechanism is used to fix the source tube 2, which passes through the mounting tube 1, within the mounting tube 1 such that the sealed end 29 of the source tube 2 is located within the target tube 9 and the open end 28 is located outside the target tube 9. Specifically, when the device is installed, one end of the source protection pipe 2 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 one end outside the target tube 9 is opened; the source pipe 2 penetrating through the installation pipe 1 is fixed with the installation pipe 1 by a 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 intended to be arranged 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 end with a connection mechanism for the radioactive material 5. 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 second fixing mechanism is used for fixing the source rod 3 inserted into the source tube 2 through the opening of the open end of the source tube 2 into the source tube 2, so that the radioactive material 5 provided at the end of the source rod 3 is pushed to the sealed end of the source tube 2, and the radioactive material 5 as the radioactive source 100 is provided in the target tube 9.

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.

It should be noted that the radiation source tube inside mounting device 400 of the present invention is generally an assembly of parts in a discrete state. The assembly into the structure shown in fig. 1, 2, 3 is only required when actually measured or applied.

It is to be noted that, in the above-described structure, the target pipe 9 is a pipe to be measured, and the installation pipe 1 is a member for welding to the target pipe 9. 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 radioactive source in-tube mounting apparatus for disposing a radioactive source (100) in a target tube (9) such that gamma rays emitted from the radioactive source (100) in the target tube (9) can be detected by a probe (200) disposed outside the tube to thereby measure the density of a fluid or slurry flowing through the target tube (9); the device comprises an installation tube (1), a source protection tube (2) and a source rod (3); the mounting pipe (1) is fixedly connected and communicated with the target pipe (9); one end of the source protection tube (2) is sealed, and the other end is opened; a first fixing mechanism which is matched with each other is arranged between the source protection pipe (2) and the installation pipe (1); the first fixing mechanism is used for fixing the source protection pipe (2) penetrating through the installation pipe (1) in the installation pipe (1), so that the sealing end of the source protection pipe (2) is positioned in the target pipe (9), and the opening end of the source protection pipe is positioned outside the target pipe (9); the tail end of the source rod (3) is provided with a connecting mechanism for arranging radioactive materials (5); a second fixing mechanism which is matched with each other is arranged between the source rod (3) and the source protection tube (2); the second fixing mechanism is used for fixing the source rod (3) inserted into the source protection tube (2) through the opening of the opening end of the source protection tube (2) in the source protection tube (2), so that the radioactive material (5) arranged at the tail end of the source rod (3) is pushed to the sealing end of the source protection tube (2), and the radioactive material (5) serving as a radioactive source (100) is arranged in a target tube (9).

2. The radioactive source tube interior mounting apparatus of claim 1, further comprising a radioactive source (100); the radioactive source (100) is an exempt source.

3. The radioactive source in-tube mounting apparatus of claim 2, wherein said exempt source is sodium-22.

4. The radioactive source tube inside mounting device according to claim 1, further characterized in that the device is such that the radioactive source (100) is arranged inside the target tube (9) within an area not more than half the inner radius of the target tube (9) from the center of the target tube (9).

5. The radioactive source tube interior mounting device according to claim 1, wherein the first fixing mechanism comprises a first flange (11) arranged at the tail end of the mounting tube (1) and a second flange (21) arranged at the opening end of the source protection tube (2); the second flange (21) and the first flange (11) can be fastened together by bolts.

6. Radioactive source inline mounting arrangement according to claim 5, further comprising a gasket (4) for being arranged between the first flange (11) and the second flange (21).

7. The radioactive source tube inside mounting device according to claim 1, wherein the second fixing mechanism 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) can be arranged in the source protection pipe (2) in a thread matching mode.

8. The radioactive source tube inside-mounting device according to claim 1, further comprising a bayonet tube (6) serving as a target tube (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.

9. A radioactive source tube inside mounting device according to claim 1, wherein 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 the flow of fluid or slurry in the target tube (9).

10. The radioactive source tube interior installation device according to claim 9, wherein an axial inclined included angle between the source protection tube (2) and the target tube (9) is 20-60 degrees.

11. The radioactive source tube inside mounting device according to claim 9, wherein the source tube (2) and the target tube (9) intersect axially.

12. A densitometer includes a probe (200) and a calculating portion (300); the probe (200) is used for detecting gamma rays emitted by the radiation source (100); a calculating part (300) for calculating the density of the measured object by connecting the probe (200) and acquiring the gamma ray count or density detected by the probe (200); the densimeter is characterized by also comprising a radioactive source tube inner installation device (400); the radioactive source tube-in-tube mounting device (400) is used for arranging a radioactive source (100) in a target tube (9), so that gamma rays radiated by the radioactive source (100) in the target tube (9) can be detected by the probe (200) arranged outside the target tube, and a calculating part (300) can calculate the density of fluid or slurry flowing through the target tube (9).

13. The densitometer of claim 12, wherein the radioactive source in-tube mounting device (400) is the radioactive source in-tube mounting device of claim 5.