Cryogenic hopper of balls for cold neutron moderator

FIELD: power engineering.

SUBSTANCE: invention relates to facilities for dosing of loose material in the form of solid balls, in particular, balls from frozen aromatic hydrocarbons, and is designed for supply of a working substance (balls) into a pneumatic tract with cold gas of helium for their subsequent delivery into a chamber of a cold quick neutron moderator of an intense source (a nuclear reactor or a neutron-producing target of an accelerator). The invention is aimed at improvement of temperature stability in a hopper and at provision of controlled speed of balls dosing. In the proposed device walls of the hopper and a part of a helium-feeding pipe are made of copper, and a dosing element represents one thin metal disc with holes of a certain diameter arranged in the lower end part of the hopper instead of the bottom. When the disc is fixed, balls do not drop from the hopper. In the dosing mode the disc is put into step rotation by a controlled step motor, the dropping speed is defined by the pitch size of disc rotation, frequency of steps repetition and the number of holes in the disc. High heat conductivity of copper provides for low temperature in the hopper and on the disc, which is close to helium temperature in the pneumatic tract.

EFFECT: exclusion of forced cooling of a hopper with liquid nitrogen.

1 cl, 1 dwg

 

The invention relates to the metering of bulk material in the form of solid beads, in particular balls of frozen aromatic hydrocarbons, and is intended for supply of the working substance (balls) in the pneumatic path with cold helium gas for subsequent delivery into the chamber of the cold moderator of fast neutrons intense source (nuclear reactor or nitrosopropane target accelerator).

Known metering device for supplying the solid balls of frozen aromatic hydrocarbons (a mixture of mesitylene and m-xylene) in the pneumatic path with cold helium gas for delivery into the chamber of a cold neutron moderator, with a cylindrical steel tank for the balls, with tanks of liquid nitrogen, with the disc on the bottom of the bunker with the hole diameter larger than the diameter of balls and located on the arc of a circle, with the shaft, designed for uniform rotation of the disk, with one outlet at the bottom of the hopper diameter substantially larger than the diameter of the balls, the center of which lies on a circle of the same diameter as the diameter of the circle location holes in the disk, and the disk in the area of the outlet is cut off; the description in the work of S.A. Kulikov, A. Belyakov, M.V. Bulavin, E.N. Kulagin, A. Kustov, K.A. Mukhin, A. Fedorov, E.P. Shabalin, CU Shabalin, Full scale model of peletized cold neutron moderators for the IBR-2M reactor. Proceedings of International Collaboration on Advanced Neutron Sources (ICANS XIX), PSI, Grindelwald, Switzerland, 2010.

The disadvantage of the dispenser is the web clipper, which promotes the formation of congestion of the balls during rotation of the disk and then Defrag. In addition, the liquid nitrogen cooling is not possible to achieve a low temperature at the bottom of the hopper and on the disk and also inconvenient in operation.

The objective of the invention is to provide a low temperature of the hopper without the use of tanks with liquid nitrogen and save desired and adjustable speed dispensing balls without defragmentation.

The problem is solved in that in cryogenic dispenser balls for cold neutron moderator, comprising a cylindrical tank for the balls, the disk dispenser above the bottom of the hopper, the drive of the dosing device and the receiver of the balls, the lower part of the shell of the hopper balls, funnel receiver beads and the adjacent portion of the pneumatic transport pipe made of copper, the upper part of the shell is made of thin stainless steel disk dispenser is one thin steel disk, while the bottom of the hopper, with a small number of holes, diameter 10-20% larger than the diameter of the dosed balls resting on the periphery of the bronze liner-the bearing and the drive shaft of the drive through the seal in the flange of the hopper is connected with the stepper motor, having a special program of rotation to the inner wall of the pipe receiver balls attached to a metal grid.

The main distinguishing features of the copper shell and more simple, gentle way of dosing provide the desired temperature in the hopper and adjustable feed balls into pneumatic transport pipe without destroying the balls due to the intermittent rotation of the disk and the lack of a slam.

Additional features add to the dispenser the following technical properties: the direct proximity of the pneumatic transport pipe from the metering disc and the presence of a metal grid and create conditions for a reliable account of balls that fall in pneumotach, through the use of the effect of dynamic pressure difference of gas while passing a slow-moving ball on a short interval between sampling points on gas differential pressure gauge.

The invention is illustrated in the drawing and photo of the dispenser; photograph made without screen-vacuum insulation and vacuum shroud.

The dispenser consists of a hopper of balls with a cylindrical cavity 4, with the upper flange and the cover 2, the metering disk with holes 5, mounted on the drive shaft 3, the actuator 1. The upper half shell of the hopper 8 is made of thin stainless steel, bottom part 9 is made of copper. Disk based peripheral part on Bron the new bearing. In the lower part, below the disc, a hopper connected with the pneumatic tube 6 conical transition funnel 10. Dispenser insulated screen-vacuum insulation located inside the casing 7. In the tank cover has a nozzle 11 for filling portions of the balls intended for dispensing.

The dispenser operates as follows.

After the cold helium with a temperature of 80-90 K) in pneumotach and cooling tank up to the same temperature, aided by the copper wall of the silo and pneumotropic (bunker has a thermal screen-vacuum insulation) is inserted through the pipe 11 special funnel is loaded into the hopper cold (at a temperature slightly above the temperature of liquid nitrogen) balls of solid mesitylene (or other material) to the level not exceeding the upper part of the copper shell of the bunker. The funnel is removed, the socket is closed and the stepping motor 12, the rotating metering disk. Due to the intermittent rotation of the disc, the balls fall through the holes of the disk in pneumotach with a controlled frequency. The narrowness of the holes in the disk (10-20% larger than the diameter of the balls) and a small amount (2 to 24, depending on the desired speed of ejection of the balls) determine a relatively uniform average time release balls without the help of the distributing device, which is used in the prototype. N the example, in one step of rotation of the disk equal to 1/4 of the diameter of the ball is dropped on average 0.12-0.14 ball in one hole, or about one ball with 8 holes. The ejection velocity of the balls is approximately proportional to the step size of the rotation. The variation in the number of balls thrown in one step, can be estimated using the distribution law of random variables Poisson.

When loading the balls into the hopper through the pipe may get nitrogen or air into the hopper and pneumotach. In this case, after filling balls in the hopper produce clean helium pneumotach by running the gas through a cold trap.

The described dispenser works within complex cold ball moderator neutron research reactor IBR-2M.

1. Cryogenic dispenser balls for cold neutron moderator, comprising a cylindrical tank for the balls, the disk dispenser above the bottom of the hopper, the drive of the feeder and receiver balls, characterized in that the lower part of the shell of the hopper balls, funnel receiver beads and the adjacent portion of the pneumatic transport pipe made of copper, the upper part of the shell is made of thin stainless steel disk dispenser is one thin steel disk, while the bottom of the hopper, with a small number of holes, diameter 10-20% more dimetridazole balls resting on the periphery of the bronze liner-bearing and the drive shaft of the drive through the seal in the flange of the hopper is connected with the stepper motor, having a special program of rotation.

2. The dispenser according to claim 1, characterized in that the inner wall of the pipe receiver balls attached to a metal grid.



 

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SUBSTANCE: invention relates to facilities for dosing of loose material in the form of solid balls, in particular, balls from frozen aromatic hydrocarbons, and is designed for supply of a working substance (balls) into a pneumatic tract with cold gas of helium for their subsequent delivery into a chamber of a cold quick neutron moderator of an intense source (a nuclear reactor or a neutron-producing target of an accelerator). The invention is aimed at improvement of temperature stability in a hopper and at provision of controlled speed of balls dosing. In the proposed device walls of the hopper and a part of a helium-feeding pipe are made of copper, and a dosing element represents one thin metal disc with holes of a certain diameter arranged in the lower end part of the hopper instead of the bottom. When the disc is fixed, balls do not drop from the hopper. In the dosing mode the disc is put into step rotation by a controlled step motor, the dropping speed is defined by the pitch size of disc rotation, frequency of steps repetition and the number of holes in the disc. High heat conductivity of copper provides for low temperature in the hopper and on the disc, which is close to helium temperature in the pneumatic tract.

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9 cl, 4 dwg

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