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