RU2640240C1 - Device for molten metal sampling - Google Patents

Abstract

FIELD: measuring equipment.SUBSTANCE: device comprises a sample fixation tank 1, an air tube 2, the cavity of which is connected with the cavity of the tank 1, and a tank 1 displacement mechanism 3. The tank 1 is provided with a lid 4 and a bottom with a hole, the diameter of which is smaller than the diameter of the droplet of the withdrawn liquid. The cavity of the tube 2 is connected with the cavity of the tank 1 through the lid 4. Inside the cylinder 1 there is a locking element 5, the material of which has a density less than the density of the withdrawn liquid, and it is thus designed to move along the height when the level of the sample in the tank 1 changes.EFFECT: invention allows to eliminate the blockage of the tube cavity with the congealing metal and the possibility of sample leakage during transportation.3 cl, 1 dwg

Description

The invention relates to a device for sampling in a liquid or fluid state and can be used in nuclear reactors for sampling a liquid metal coolant.

The closest in technical essence to the invention is a device for sampling in a liquid or fluid state, containing a container for fixing the sample with a hole in the bottom, an air tube with a valve and a mechanism for moving the tank, while the tank is equipped with a lid connected to the air tube in this way that the cavity of the tube communicates with the cavity of the tank through the lid (immersion cylinder for point sampling "Target", equipment catalog http://millab.ru/equipments/tsilindr target /, publ. 1996).

In the known device, a tube passes through the opening of the bottom with a gap relative to the inner surface of the container. The tube is the path to the sample, and the annular gap between it and the inner surface of the container is the sample fixation volume.

The known device is used as follows.

A container (cylinder) is immersed in a liquid to a predetermined depth using a movement mechanism. In this case, the movement mechanism is a coil on which an air tube with a closed valve is wound, so immersion of the container is carried out by unwinding the air tube. Upon reaching a predetermined immersion depth, the cylinder is stopped, the valve on the air tube is opened. After opening the valve, the air pressure in the tube tends to be equal to atmospheric, and the liquid pressure at the sampling point is higher than atmospheric by the value of hydrostatic pressure at this point. Due to the pressure difference in the air tube and at the sampling point, the liquid begins to flow through the tube into the cylinder cavity, accumulating and fixing in the gap. Then the container is removed, the lid is unscrewed, the sample is sent for analysis of its composition.

However, in the case of sampling a liquid metal, for example, a liquid metal coolant of a nuclear reactor, the use of the known device will cause a number of inconveniences. As noted above, after opening the valve, the air pressure inside the cylinder tends to equal atmospheric, and the fluid pressure at the sampling point is higher than atmospheric. If the cylinder is submerged under the liquid level to a depth exceeding its height, then the liquid, filling the cylinder, enters the air tube. If the liquid being sampled is molten metal, it can freeze in the air tube. When the metal solidifies in the air tube, the communication of the cavities ceases, and consequently, the subsequent sampling procedures will be possible only after cleaning the air tube from the solidified sample in it. In addition, when transporting the sample to the place of its extraction from the cylinder with its axis deviating from the vertical position, part of the sample will pour down through the tube. Such a situation is possible when moving the cylinder along an inclined channel in the reactor vessel, which can be performed in such a way as to exclude direct shot radiation from the reactor beyond its limits through the channel or due to the crowding of the space on the reactor cover with other equipment.

Thus, the disadvantages of the known device is the difficulty in operation when sampling a metal melt, due to the possibility of leakage of the sample into the air tube with its subsequent closure, which will lead to additional manipulations to clean the tube for subsequent sampling, and problems when transporting the sample in an inclined position from -for the possibility of leakage of the sample from the cylinder.

The technical problem of the present invention is the sampling of molten metal, including liquid metal coolant of a nuclear reactor.

The technical result of the invention is the exclusion of clogging of the cavity of the tube with a hardening metal and the possibility of leakage of the sample during transportation.

The technical result is achieved by that in a device for sampling in a liquid or fluid state, containing a container for fixing the sample with a cap and a hole in the bottom, an air tube with a pressure control device, the cavity of which is in communication with the cavity of the container through the cover, and a mechanism for moving the container inside the container has a locking element for blocking the passage of the air tube with the possibility of its movement along the height of the container along with the liquid level due to the fact that the locking element is made of material the ratio of which is less than the density of the selected fluid, and the hole in the bottom of the tank is made with a diameter smaller than the diameter of the droplet of the selected fluid. In addition, the locking element may be profiled in the shape of the lid.

The combination of the claimed features will prevent the ingress of the sample into the cavity of the air tube and use the device for sampling liquid metal without additional costs for cleaning the tube, since the locking element will exclude the message of the cavity of the tube and capacity upon reaching the desired level of the sample, and the hole in the container with a diameter smaller than the separation diameter drops of the selected fluid at a given pressure drop will ensure that the sample does not leak out of the tank due to the action of surface tension forces and the constancy of the level of samples s during transportation of the container, and hence the tight contact of the element with the air tube in order to overlap its passage section.

The invention is illustrated in the drawing, where in FIG. 1 shows a device for sampling (longitudinal section).

The device contains a container for fixing the sample 1, an air tube 2, the cavity of which is in communication with the cavity of the container 1, and a movement mechanism 3 of the container 1.

The tank 1 is made, for example, in the form of a hollow cylinder, one end of which is provided with a cover 4, and the other a bottom with an opening, the diameter of which is less than the diameter of the separation of a drop of sampled liquid. The communication of the cavity of the tube 2 with the cavity of the tank 1 is carried out through the cover 4. Inside the cylinder 1 there is a locking element 5 with the possibility of movement along the height due to a change in the level of the sample, the material of which has a density lower than the density of the liquid being sampled. The locking element 5 seals the container 1 along the sealing surface of the cover 4. For example, a ball and a conical cover.

The movement mechanism 3 of the container 1 is a coil on which the tube 2 is wound. At the end, the tube 2 is equipped with a pressure control mechanism, the function of which in this case is the valve 6. In another embodiment of the sampling device, the pressure control mechanism can be made in the form of a vacuum pump.

The device operates as follows.

Capacity 1 by rotation of the movement mechanism 3 - the coil - and unwinding the tube 2 is immersed in the liquid metal coolant.

To take and hold the sample after immersion of the container 1 with its lower end in the melt inside the tube 2 create and maintain a pressure that meets the condition:

To prevent leakage of the sample from the tank 1 into the tube 2, the condition must be met:

Where

p ₁ - pressure at the point of sampling, Pa;

σ is the surface tension coefficient of the melt, N / m;

d ₀ is the diameter of the hole in the bottom of the tank, m;

d _ger is the hydraulic diameter of the gap remaining between the cover and the sealing element after sealing, m;

ρ is the density of the melt, kg / m ³ ;

h - the height of the filled part of the vessel, m;

g - acceleration of gravity, m / s ² .

Thus, after immersing the tank 1 under the coolant level, the pressure in the tube 2 is reduced to the required value, and the melt begins to flow through the hole in the bottom of the tank 1 due to the pressure drop that has arisen. With an increase in the level of the sample in the container 1, the locking element 5 rises, which, finally, abuts the lid 4 and blocks the communication of the cavity of the tube 2 with the cavity of the vessel 1. The metal ceases to enter the vessel 1, after which it is removed from the reactor. The locking element 5 may have a portion protruding above the level of the sample, which is profiled in the shape of the lid 4, which simplifies the contact of the element 5 with the sealing surface of the lid 4.

When transporting the sample to maintain tight contact of the floor element 5 with the tube 2, it is necessary to ensure the constancy of the level of the sample inside the cylinder. Otherwise, with a decrease in the level of the sample, the element 5 will also drop, and the molten metal of the sample can penetrate the tube 2 when the tank deviates from the vertical and / or with a sharp change in pressure drop p ₁ - p ₂ . A hole in the bottom of the container 1, the diameter of which is smaller than the diameter of the droplet of the sampled liquid, allows the sample to be held inside the container 1 during transportation due to the surface tension of the melt from the prior art drop separation condition, thereby maintaining a constant sample level and tight contact of element 5 with tube end hole 2.

After removing the container 1 from the reactor and cooling the sample until it hardens, the cover 4 of the container 1 is unscrewed, and the container 1 with the sample is transferred to the laboratory, where the sample is removed and analyzed.

In the particular case of lead sampling, the container 1 and element 5 are made of steel, since a passivating oxide coating is formed on them. The selected melt has low adhesion to the surfaces of the container for fixing the sample 1 and the locking element 5, therefore, after removing the sample on the walls of the container 1 and on the surface of the element 5 there is no significant amount of solidified melt. Residual samples can be washed from their surfaces with special chemicals and these elements of the device can be reused.

Claims (3)

1. A device for sampling in a liquid or fluid state, containing a container for fixing the sample with a cap and a hole in the bottom, a tube with a pressure control device, the cavity of which is in communication with the cavity of the container through the cover, and a mechanism for moving the container, characterized in that inside the container an element that locks the outlet section of the tube is placed with the ability to move it in height by changing the level of the sample, while the overlap element is made of material whose density is less than the density of the sampled fluid, and the holes a bottom tank performed a diameter smaller than the diameter of the withdrawn liquid droplets. 2. The device according to claim 1, characterized in that the overlap element is profiled in the shape of a lid. 3. The device according to claim 1, characterized in that the tank and the floor element are made of steel.

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