JPS59200090A - Super low temperature liquefied gas pump - Google Patents

Abstract

PURPOSE:To make it possible to stably operate a gas pump, by designing the gas pump in a double layer structure of heat insulating materials and accommodating a drive shaft, motor and bearings in an ordinary temperature area formed in a super low temperature liquefied gas, thereby to prevent a positional change due to thermal deformation among the drive shaft, housing and internal heat insulating layer. CONSTITUTION:There is provided an inner heat insulating layer 14 inside of an outer heat insulating layer 13. In a housing 15 inside of the inner heat insulating layer 14, a drive shaft 2, motor 4 and bearings 24, 25 and 28 are accommodated. Further, a laminated heated insulator 23 is wound around an inside surface of the outer heat insulating layer 13 and an outside surface of the inner heat insulating layer 14. A flange 17 is provided with a vacuum exhaust pipe 40 so as to maintain a space between both the heat insulating layers under vacuum and thereby to effect heat insulation. With this arrangement, during introducing liquefied gas into a spacing between the drive shaft 2 and the inside of the housing 15, and another spacing between the outside of the housing 15 and the inner heat insulating layer 14 so as to cool each member, it is possible to independently adjust flow of the gas and uniformly cool the drive shaft 2, inside and outside of the housing 15 and the inner and outer heat insulating layers 14 and 13, thereby eliminating a positional change of each member due to thermal deformation and permitting a stable operation of the pump.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a pump for supplying cryogenic liquefied gas, and particularly to a pump suitable for supplying liquid helium.

[Background of the invention]

In conventional cryogenic liquefied gas pumps, the motor is installed at the top of the liquefied gas storage tank or cryostand, the drive shaft is extended into the tank, the impeller is connected to the bottom end, and the middle or top of the impeller is mounted with multiple ball bearings. I support it. Heat intrusion from normal temperature areas is prevented by using low thermal conductivity materials such as stainless steel for the drive shaft and casing (for example, L-B-D
inaburger-al-, cryogenics
17 +A7, 439-440 (1977)). For this reason, the drive shaft is long and cannot rotate at high speeds, resulting in a complex structure.Also, ball bearings that are lubricated by liquefied or vaporized gas must be used, resulting in high wear and low reliability. There were drawbacks such as.

[Purpose of the invention]

The object of the present invention is to replace conventional cryogenic liquefied gas pumps.

The objective is to solve the drawbacks and provide a pump with excellent performance and reliability.

[Summary of the invention]

The present invention cools the drive shaft, nozzle, and insulation tank using the latent heat of vaporization during vaporization of liquefied gas and the sensible heat of low-temperature gas, thereby improving performance by reducing heat intrusion from the normal temperature region to the extremely low temperature region. At the same time, it prevents thermal deformation of the drive shaft and nozzle,
This improves reliability by ensuring stable operation.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIG. An internal insulation tank 14 is provided inside the external insulation tank 13, and a drive shaft 2, a motor 4. Bearings 24, 25. and 28. The upper parts of the external heat insulating tank 13 and the internal heat insulating tank 14 are fixed to a flange 17, and the lower ends are fixed via a bellows 19 so as to absorb deformation due to heat contraction. A radiation shield 21 is provided between both the heat insulating tanks, and the lower part is held by a spacer 22. Further, a laminated heat insulating material 23 is wrapped around the inner surface of the external heat insulating tank 13 and the outer surface of the internal heat insulating tank 14. Further, a vacuum exhaust pipe 40 is provided on the flange 17 to create a vacuum between the two heat insulating tanks and insulate the tank. The housing 15 is secured to the upper flange 18 by a support tube 16. 7. A discharge pipe 20 for vaporized helium gas and a conduit 45 for a lead wire 44 of the 47° motor are connected to the 7 flange 18. Further, the helium gas discharge pipes 20 and 47 are provided with flow rate control valves 46 and 48. The seven flange 17 for assembling the heat insulating tank is attached to the upper plate 5 of a liquid helium storage tank or cryostat, and the flange 18 for assembling the pump body is further attached to the flange 17 for assembling the heat insulating tank. The pump is installed so that the main body is at the liquid helium level 41.

The pump drive section will be explained with reference to FIG. The impeller 1 is attached to the lower end of the drive shaft 2, the rotor 30 of the motor is attached to the upper center, and the upper end is made into a disk 29 for a thrust bearing. Rotates the stator 31 of the motor (provided at a position opposite to the stator 30, and journal bearings 24 and 2
5 will be provided. In this example, a tail/gating pad type dynamic pressure gas bearing is used.
is supported by pivot 27. A dynamic pressure gas bearing is also used for the thrust bearing 28. Impeller 1 and lower journal bearing 2
4, three stages of shields 35 are provided within the housing of the drive shaft 2, and a solid heat insulating material 36 such as foamed polyethylene is installed between them. The lower end of this part is in contact with liquid helium, and the upper end is near room temperature. In addition, in FIG. 2, the lead wire to the stator 31 of the motor is omitted.

When the stator 31 of the motor is energized and the pump is rotated, liquid helium is sucked in through the suction port 8 and discharged through the discharge port 9. If the piping to the load is connected here, liquid helium will be sent to the load.

Liquid and lithium enter the gap 37 around the drive shaft 2 from the bottom, vaporize due to the heat entering from the top, and the bearing 24 and stator 3
1. The gap 37 between the bearings 25 and 28 and the drive shaft 2 is raised, and the discharge hole 32. It is exhausted to the outside of the system through the support pipe 16, the discharge pipe 20, and the flow rate control valve 46. Similarly, liquid helium enters the gap 38 between the housing 15 and the internal heat insulating tank 14 from the bottom, vaporizes in the heat insulating material section at the bottom, and flows into the internal heat insulating tank 14 and into the discharge pipe 47. It is exhausted to the outside of the system via the flow control valve 48. The amount of helium gas flowing out from the exhaust pipes 20 and 47 is a ratio of 1:5 to 50, corresponding to the amount of heat introduced by conduction through the S housing on the drive shaft and the drive shaft side, and the amount of heat absorbed through conduction through the outer housing and internal insulation tank. Adjusted within range. By separately adjusting the amount of helium gas rising through the gaps 37 and 38, the amount of heat intrusion is reduced, and at the same time, the drive shaft, nozzle, and internal insulation tank are uniformly cooled, allowing stable operation of the pump. It became.

In addition to conduction from the room temperature section, there is also heat generated when the motor rotates, but a cooling coil or jacket is installed in the room temperature section of the No.
It can also be removed.

[Effects of the Invention] According to the present invention, a drive shaft and a motor can be manufactured by using a double heat insulating layer structure and providing a room temperature region in a cryogenic liquefied gas.

When introducing and cooling liquefied gas into the gap between the drive shaft and the inner housing, and between the outer housing and the internal insulation tank using a liquefied gas pump that houses a bearing and a bearing, the gas flow rate can be adjusted separately to reduce the amount of heat intruding into each part. It has the effect of efficiently reducing the amount of heat that enters. In addition, the drive shaft, the inside and outside of the housing, and the internal insulation layer are uniformly cooled.
This has the effect of enabling stable operation without causing any positional changes between the drive shaft and the housing or internal thermal insulation tank due to thermal deformation.

[Brief explanation of the drawing]

FIG. 1 is a vertical cross-sectional view of the entire liquefied gas pump according to an embodiment of the present invention, and FIG. 2 is a vertical cross-sectional view of the pump driving portion of FIG. 1. l... Impeller, 2... Drive shaft, 14... Internal insulation tank, 15... Housing, 20... Discharge pipe, 32...
...Drain hole, 36...Insulating material, 37...Gap, 38
...Gap, 46...Flow rate control valve, 47...Discharge pipe, 48...Flow rate control valve. Figure 2 Continued from page 1 0 Inventor Hiroki Kajiwara 794 Higashitoyoi, Kudamatsu City Kasado Factory, Hitachi, Ltd.

Claims (1)

[Claims] 1. Consisting of an external heat insulating tank, an internal heat insulating tank, a pump housing, and a pump body, an internal heat insulating tank is installed within the external heat insulating tank,
A pump drive shaft in a pump that is flexibly connected at the bottom and vacuum insulated, and the pump body is housed in a housing and housed in an internal insulation tank. A cryogenic liquefied gas pump characterized in that a gap and a discharge hole to the outside are provided inside or along the surface of a housing and an internal heat insulating tank, and cooling is performed by flowing liquefied gas. 2.Adjust the gas discharge amount to the exhaust hole to the outside of each gap.3.Adjust the gap for introducing liquefied gas to the drive shaft and inside the housing.