GROUND FREEZING INSTALLATION ACCOMMODATING THERMAL CONTRACTION OF METAL FEED PIPES

Abstract

A ground freezing system includes a metal feed pipe for delivering refrigerant to the lower end of a freeze pipe installed in a bore in the ground. The feed pipe is supported on a compression spring which accommodates thermal contraction of the feed pipe while maintaining support of its weight.

Description

DESCRIPTION OF THE DRAWING

In the accompanying drawing which forms a part of the specification and is to be read in conjunction therewith:

FIG. 1 is a sectional diagrammatic view of a ground freezing installation equipped with a feed pipe support arrangement constructed according to a preferred embodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 1 depicts a ground freezing system that is installed in a vertical bore 10 which is drilled or otherwise formed to extend downwardly into the ground 11 from the ground surface 12. A cylindrical metal freeze pipe 14 is installed in the bore 10 and extends downwardly in the bore to its bottom or base end 16. The freeze pipe 14 fits closely in the bore 10. A feed pipe 18 which is smaller in diameter than the freeze pipe extends concentrically within the freeze pipe 14. The upper end of the feed pipe 18 is located above the ground surface 12, and the feed pipe 18 has a lower discharge end 20 which is open in order to discharge refrigerant into the freeze pipe 14 at the bottom end portion of the freeze pipe. The discharge end 20 of the feed pipe is spaced above the bottom 16 of the bore. In accordance with the invention, the feed pipe 18 is constructed of metal and is preferably constructed of steel.

The feed pipe 18 is supported at its lower end by a resilient element which may take the form of a compression spring 22 interposed between the base 16 of the bore 10 and the lower end 20 of the feed pipe. The spring 22 may be a conventional coiled compression spring. The spring 22 is constructed such that it is in a state of compression when the feed pipe 18 is not subjected to the cooling effects of refrigerant. The spring 22 is compressed between the base 16 of bore 10 and the feed pipe 18 in order to support the weight of the feed pipe. The spring 22 is able to expand in order to maintain support of the weight of the feed pipe 18 if the feed pipe contracts such that its lower end 20 rises due to thermal contraction.

The upper end of the feed pipe 18 extends through a fitting 23 on the top end of the freeze pipe 14. The upper end of pipe 18 is connected through a valve 24 with a supply hose 26. The supply hose 26 extends from a suitable source of refrigerant (not shown) and is able to direct the refrigerant from the hose 26 through valve 24 to the feed pipe 18.

At a location above the level of the ground surface 12, the freeze pipe 14 is provided with a horizontal discharge pipe 28 on one side. The discharge pipe 28 connects through a valve 30 with a discharge hose 32 which directs refrigerant from the freeze pipe to a refrigeration plant or other apparatus that may cool the refrigerant for use in another bore.

In operation of the ground freezing system, a suitable refrigerant is pumped through hose 26 and valve 24 into the upper end of the feed pipe 18. The refrigerant is pumped downwardly through the freeze pipe 18 as indicated by the directional arrows 34. The refrigerant is discharged from freeze pipe 18 through its open lower ends 20 and into the bottom end portion of the freeze pipe 14. The refrigerant then flows upwardly within the freeze pipe 14 as indicated by the directional arrows 36, thereby extracting heat from the ground 11 that surrounds the well bore 10. Eventually, the ground 11 freezes. The refrigerant that passes through the freeze pipe 14 is discharged through pipe 28, valve 30 and the discharge hose 32.

As the refrigerant is pumped through the feed pipe 18, the feed pipe is cooled to a low temperature and contracts as a result of thermal contraction. Consequently, the discharge end 20 of the feed pipe moves upwardly. The presence of the spring 22 and its ability to expand due to its resiliency allows the lower end 20 of the feed pipe to rise while the spring 22 is able to maintain its support of the weight of the feed pipe 18. Therefore, undue stress on the top fitting 23 or other part of pipe system is avoided.

In this manner, the effects of thermal contraction are accommodated while maintaining support of the feed pipe weight from beneath the feed pipe. By constructing the feed pipe 18 of a metal such as steel, its thermal contraction is minimized so that the lower end 20 does not rise sufficiently to exceed the capacity of the spring 22 to maintain support of the feed pipe. Thus, adequate structural support of the feed pipe 18 is maintained while the bottom end portion of the freeze pipe 14 down to the bore base 16 is supplied with refrigerant to effect freezing around the entire depth of the bore 10.

From the foregoing it will be seen that this invention is one well adapted to attain all ends and objects hereinabove set forth together with the other advantages which are obvious and which are inherent to the structure.

It will be understood that certain features and subcombinations are of utility and may be employed without reference to other features and subcombinations. This is contemplated by and is within the scope of the claims.

Since many possible embodiments may be made of the invention without departing from the scope thereof, it is to be understood that all matter herein set forth or shown in the accompanying drawings is to be interpreted as illustrative, and not in a limiting sense

Claims

1. Apparatus for freezing ground around a bore extending into the ground from the ground surface, said apparatus comprising: a freeze pipe installed in the bore and having a lower end near a base of the bore;a feed pipe in said freeze pipe having an upper end portion for receiving a refrigerant, said feed pipe comprising metal and having a bottom discharge end located above said base of the bore for discharging the refrigerant into the freeze pipe for upward flow therein to extract heat from the ground around the bore; anda resilient element interposed between said discharge end of said feed pipe and said base of the bore for supporting the feed pipe in a manner accommodating thermal contraction thereof while maintaining support of the feed pipe.

2. Apparatus as set forth in claim 1, wherein said resilient element comprises a compression spring.

3. Apparatus as set forth in claim 1, wherein said feed pipe comprises steel.

4. Apparatus as set forth in claim 3, wherein said resilient element comprises a compression spring.

5. Ground freezing apparatus comprising: a bore extending from a ground surface into the ground and terminating at a base;a freeze pipe installed in said bore;a metal feed pipe extending within said freeze pipe and having a discharge end for discharging refrigerant into said freeze pipe near said base for upward flow of the refrigerant in the freeze pipe to effect freezing of the ground around said bore; andresilient means beneath said feed pipe for supporting the weight of the feed pipe while accommodating thermal contraction thereof.

6. Apparatus as set forth in claim 5, wherein said resilient means comprises a compressible element able to expand when said discharge end of the feed pipe rises upon thermal contraction of the feed pipe.

7. Apparatus as set forth in claim 6, wherein said compressible element comprises a compression spring.

8. Apparatus as set forth in claim 7, wherein said feed pipe comprises steel.

9. Apparatus as set forth in claim 5, wherein said feed pipe comprises steel.

10. A ground freezing installation comprising: a bore extending into the ground from a surface thereof and terminating at a base;a freeze pipe lining said bore;a metal feed pipe having an upper end portion for receiving refrigerant and a lower end portion for discharging the refrigerant into said freeze pipe above said base to effect upward flow of the refrigerant in the freeze pipe for freezing of the ground around the bore;a refrigerant supply operable to apply refrigerant to said upper end portion of the feed pipe;a refrigerant collection conduit for collecting refrigerant from the freeze pipe at a location near the ground surface; andmeans beneath said feed pipe for supporting the weight of the feed pipe and accommodating thermal contraction thereof.

11. An installation as set forth in claim 10, wherein said means beneath said feed pipe comprises a compressible element extending between said base of the bore and said lower end portion of the feed pipe, said compressible element being constructed to expand to maintain support of the feed pipe upon rising of said lower end due to thermal contraction of the feed pipe.

12. An installation as set forth in claim 11, wherein said compressible element comprises a compression spring.

13. An installation as set forth in claim 12, wherein said feed pipe comprises steel.

14. An installation as set forth in claim 10, wherein said feed pipe comprises steel.