A segmented control type liquid nitrogen freezer and its working method

Abstract

The invention discloses a segmented control type liquid nitrogen freezer and a working method, and belongs to the technical field of artificial freezing construction of underground engineering. The segmented control type liquid nitrogen freezer is composed of a vertical return gas steel pipe and liquid supply pipes winding outside the return gas steel pipe in a segmented mode. The upper end of each segmented liquid supply pipe is connected with a ground liquid nitrogen supply system through heat insulation vertical pipes arranged in the return gas pipe, and the lower ends of the liquid supplypipes are directly connected into the return gas pipe to form a liquid nitrogen circulation system. During the freezing construction, liquid nitrogen can be poured into different segmented liquid supply pipes separately through the heat insulation vertical pipes, and nitrogen gas is discharged into the atmosphere along the return gas steel pipe to complete the freezing process. The segmented control type liquid nitrogen freezer realizes the control over the freezing effects in different segment ranges and an independent liquid supply method between the liquid supply pipes of different segments, and can control the start and end freezing time of each segment separately according to the construction needs, so as to realize segmented differential freezing of a stratum and precisely control the freezing process of the liquid nitrogen.

Description

technical field [0001] The invention relates to a freezer and a working method, in particular to a segmented control type liquid nitrogen freezer and a working method which are suitable for use in the field of artificial freezing construction technology of underground engineering. Background technique [0002] In the construction of underground engineering, when encountering complex geological conditions such as water-rich soft soil strata, artificial freezing technology is often used to reinforce the soil layer to improve the performance of the stratum, so as to complete the excavation and structure construction in the water-rich stratum. Among them, liquid nitrogen freezing has the advantages of rapidity, high strength, and high efficiency, and has been widely used in underground engineering. In the traditional liquid nitrogen freezing construction, the freezer is arranged in the pre-constructed freezing hole, and liquid nitrogen is poured from the liquid supply pipe in th...

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Problems solved by technology

[0003] Since the traditional liquid nitrogen freezer freezes along the entire length of the freezing hole at the same time, when the freezing depth is large, the liquid nitrogen is vaporized in the long liquid supply pipe, resulting in poor uniformity of the frozen wall formed along the length of the freezing pipe , and it is difficult to control the liquid nitrogen gasification process, it is impossible to control the freezing process in different depth ranges, and it is also impossible to realize the segmental freezing process in different depth ranges

For example, after the excavation of the upper stratum is completed, liquid nitrogen still needs to pass through the upper liquid supply pipeline, so the freezing of the upper strata cannot be stopped, resulting in additional consumption and waste of liquid nitrogen, and increasing construction costs

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