Stratum freezing method of long spiral freezer

Abstract

The invention relates to the technical field of stratum freezing, and discloses a stratum freezing method of a long spiral freezer, which specifically comprises the following steps: after the long spiral freezer is drilled into a stratum, in a positive freezing stage, liquid nitrogen is input into a liquid supply pipe, and nitrogen discharged from a pipe body is collected through a collecting pipe; entering a maintenance freezing stage after the positive freezing stage is finished; and in the freezing maintenance stage, liquid nitrogen input is stopped, saline water is input into the liquid supply pipe for freezing maintenance, and the saline water discharged from the pipe body is collected through the collecting pipe until freezing is finished. According to the long spiral freezer, under the cooperation of the spiral blade and the pipe body, drilling and hole forming can be directly conducted, and hole forming does not need to be conducted in advance; and secondly, gas ascending along the cavity can be collected in the collecting section through the collecting pipe, recycling is achieved, low carbon and environmental protection are achieved, after the positive freezing stage adopting liquid nitrogen is finished, saline water is adopted to enter the maintenance freezing stage, and economical efficiency is better.

Description

Technical Field

[0001] The invention relates to the technical field of ground freezing, in particular to a ground freezing method using a long spiral freezer. Background Art

[0002] Ground freezing is a technology that achieves ground reinforcement by freezing rock and soil. This technology uses artificial refrigeration technology to freeze water in the ground, turning natural rock and soil into frozen soil, thereby increasing its strength and stability and isolating groundwater from underground projects. This method has been widely used in municipal engineering (such as subway construction), coal mines, deep foundation pits and other fields. In urban subway projects, it is often used in tunnel communication channel construction, shield tunneling machine entry and exit construction, and shield cutter head opening and cutting construction.

[0003] CN102979083A discloses a liquid nitrogen freezer, comprising an exhaust pipe, a liquid inlet, an exhaust port, a sealing plate, a liquid supply pipe, a through hole, a liquid supply pipe and a bottom plate, wherein the liquid supply pipe and the exhaust pipe are arranged in the liquid supply pipe through the sealing plate, the exhaust pipe is provided with an exhaust port, the exhaust port is arranged outside the liquid supply pipe, one end of the liquid supply pipe in the liquid supply pipe is provided with a bottom plate, the other end passes through the sealing plate and is provided with a liquid inlet, and the liquid supply pipe is evenly distributed with through holes. The through holes are flat and rectangular.

[0004] The above technical solution can achieve uniform freezing by evenly distributing through holes on the liquid supply pipe; the through holes are set in a flat rectangular shape, which increases the contact area between liquid nitrogen and the outside air, and improves the freezing speed and freezing effect. However, the above liquid supply pipe still requires pre-drilling holes in the formation and then burying the freezer in the hole, which is very time-consuming and labor-intensive. In addition, the freezing cost will be very high if liquid nitrogen is used for freezing. Summary of the invention

[0005] The purpose of the present application is to solve the above-mentioned problems and to provide a stratum freezing method using a long spiral freezer. The method adopts a long spiral freezer, which can directly drill holes with the cooperation of spiral leaves and a tube body without pre-drilling holes; and a cavity connected to the tube body is provided in the spiral leaves so that the low-temperature gas in the tube body can enter the cavity of the spiral leaves. The provision of the spiral leaves increases the contact area between the tube body and the stratum and improves the freezing speed. Secondly, the gas ascending along the cavity can be collected in the collection section through a collection pipe for reuse, which is more low-carbon and environmentally friendly. Moreover, after the active freezing stage using liquid nitrogen is completed, brine is used to enter the maintenance freezing stage, which is more economical.

[0006] To achieve the above objectives, this application provides the following technical solutions:

[0007] A ground freezing method of a long spiral freezer, the method relates to a long spiral freezer, the long spiral freezer comprises a tube body, a spiral leaf is arranged on the outside of the tube body, a cavity connected to the tube body is arranged inside the spiral leaf, a first partition and a second partition are arranged inside the tube body, wherein at least two first partitions and at least two second partitions are arranged;

[0008] The first partition separates the tube body into a plurality of freezing sections; the second partition separates the tube body into a collecting section, the plurality of freezing sections are located between the collecting section and the bottom end of the tube body, and two adjacent freezing sections are connected through a cavity, and the collecting section is connected to its adjacent freezing section through a cavity; the tube body is provided with liquid supply pipes corresponding to the freezing sections one by one, and the second partition is provided with a collecting pipe connected to the collecting section;

[0009] This method includes an active freezing stage and a maintenance freezing stage. Specifically, the method is as follows:

[0010] After the long spiral freezer is drilled into the formation, during the active freezing stage, liquid nitrogen is input into the liquid supply pipe, and the nitrogen discharged from the pipe body is collected through the collecting pipe, until the active freezing stage is over and the maintenance freezing stage begins; during the maintenance freezing stage, the liquid nitrogen input is stopped and brine is input into the liquid supply pipe for maintenance freezing, and the brine discharged from the pipe body is collected through the collecting pipe until the freezing is completed.

[0011] Preferably, the temperature of the brine is -25°C to -28°C, and can be -28°C, -27°C, -26°C, or -25°C, but is not limited to the listed values, and other values ​​not listed are applicable as long as they are within this range.

[0012] Preferably, the long spiral freezer is drilled into the formation by a drilling rig, and the spiral blades are all located in the formation.

[0013] Preferably, the first partition includes a horizontally arranged first plate body and a second plate body connected to the first plate body, the second plate body is arranged around the edge of the first plate body, the first plate body separates the tube body into multiple freezing sections, and the second plate body is used to close the side of the partial cavity located in the freezing section to block the connection between the tube body and the partial cavity.

[0014] Preferably, the height of the second plate is 4 / 5 to 9 / 10 of the height of the freezing section. 4 / 5 and 9 / 10 can be used, but are not limited to the listed values. Other values ​​not listed are applicable as long as they are within this range.

[0015] Preferably, the first plate body is a first plate body made of a heat insulating material.

[0016] Preferably, there are two first partitions, the two first partitions separate the tube body into three freezing sections, and there are three liquid supply pipes.

[0017] Preferably, the bottom end of the liquid supply tube is closed, and a plurality of output holes are provided on the side wall of the liquid supply tube near the bottom end thereof, and the plurality of output holes form the output end of the liquid supply tube.

[0018] Compared with the prior art, the beneficial effects of this application are:

[0019] The present application adopts a long spiral freezer, which can directly drill a hole with the cooperation of the spiral blade and the tube body without pre-drilling; and a cavity connected to the tube body is arranged in the spiral blade, so that the low-temperature gas in the tube body can enter the cavity of the spiral blade. The arrangement of the spiral blade increases the contact area between the tube body and the formation, and improves the freezing speed. Secondly, the gas ascending along the cavity can be collected by the collection pipe in the collection section to achieve reuse, which is more low-carbon and environmentally friendly. Moreover, after the active freezing stage using liquid nitrogen is completed, salt water is used to enter the maintenance freezing stage, which is more economical. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is a schematic structural diagram of a long spiral freezer of Example 1 of the present application;

[0021] Figure 2 yes Figure 1 CC section view;

[0022] Figure 3 yes Figure 2 DD cross-sectional view;

[0023] Figure 4 It is a three-dimensional view of the long spiral freezer of Example 1 of the present application.

[0024] Tube body 1; liquid supply tube 2; spiral blade 11; first partition plate 12; second partition plate 13; output hole 21; cavity 111; first plate body 121; second plate body 122; collecting tube 131; freezing section A; collecting section B. DETAILED DESCRIPTION

[0025] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0026] Example 1

[0027] refer to Figures 1 to 4, a ground freezing method of a long spiral freezer, the method relates to a long spiral freezer, the long spiral freezer comprises a tube body 1, a spiral leaf 11 is arranged on the outside of the tube body 1, a cavity 111 connected to the tube body 1 is arranged in the spiral leaf 11, a first partition 12 and a second partition 13 are arranged in the tube body 1, wherein at least two first partitions 12 and at least two second partitions 13 are arranged;

[0028] The first partition 12 separates the tube body 1 into a plurality of freezing sections A; the second partition 13 separates the tube body 1 into a collecting section B, the plurality of freezing sections A are located between the collecting section B and the bottom end of the tube body 1, and two adjacent freezing sections A are connected through a cavity 111, and a collecting section A is connected to its adjacent freezing section A through the cavity 111; a liquid supply pipe 2 corresponding to each freezing section A is provided in the tube body 1, and a collecting pipe 131 connected to the collecting section B is provided on the second partition 13;

[0029] This method includes an active freezing stage and a maintenance freezing stage. Specifically, the method is as follows:

[0030] After the long spiral freezer is drilled into the formation, in the active freezing stage, liquid nitrogen is input into the liquid supply pipe 2, and the nitrogen discharged from the tube body 1 is collected through the collecting pipe 131, until the active freezing stage is completed and the maintenance freezing stage begins; in the maintenance freezing stage, the liquid nitrogen input is stopped and brine is input into the liquid supply pipe 2 for maintenance freezing, and the brine discharged from the tube body 1 is collected through the collecting pipe 131 until the freezing is completed.

[0031] Under this design, the operator operates the long spiral drill to drill the long spiral freezer directly into the hole, and after all the spiral blades 11 are located in the formation, the long spiral drill is separated from the long spiral freezer, and the long spiral drill is operated to leave the current area;

[0032] The external liquid nitrogen delivery equipment is connected to the multiple liquid supply pipes 2 respectively, and liquid nitrogen is introduced into the liquid supply pipes 2. Under the guidance of the liquid supply pipes 2, the liquid nitrogen flows to different freezing sections A respectively, and finally exists in the pipe body 1 in the form of low-temperature nitrogen, and freezes the soil through the pipe body and the spiral blades. The low-temperature nitrogen in the pipe body 1 will continue to rise until it is discharged from the top outlet of the spiral blade cavity and enters the collection section B. It is connected to the external collection equipment through the collection pipe B, and the low-temperature gas in the collection section B is extracted in a negative pressure manner to achieve recycling.

[0033] Under the action of the first partition 12, the speed at which the low-temperature nitrogen leaves the corresponding freezing section A is limited, so that the low-temperature nitrogen can enter the cavity 111 of the freezing section A, so that the spiral blades 11 also have freezing ability. The spiral blades 11 increase the contact area between the pipe body 1 and the formation, thereby improving the freezing speed.

[0034] After the active freezing stage, the liquid nitrogen input is stopped, and the operator connects the liquid supply pipe 2 to the external brine delivery equipment, and introduces brine into the liquid supply pipe 2 to enter the maintenance freezing stage. The flow of brine is the same as the flow of cryogenic gas. Under continuous pressure input, the brine will eventually enter the collection section B, and under the action of the external collection equipment, the brine in the collection section B is collected through the collection pipe 131, thereby realizing the flow and recycling of brine.

[0035] In this way, considering the high cost of liquid nitrogen, using liquid nitrogen in the active freezing stage can achieve the freezing effect faster, and using brine to maintain freezing in the maintenance freezing stage can reduce the cost of the entire freezing process.

[0036] It should be noted here that the operator can determine whether the active freezing stage is over through the monitoring data of the temperature measuring hole.

[0037] Preferably, the temperature of the brine is -25°C to -28°C. In actual use, -28°C, -27°C, -26°C, and -25°C may be used, but are not limited to the listed values, and other values ​​not listed are applicable as long as they are within this range.

[0038] Preferably, the first partition 12 includes a horizontally arranged first plate body 121 and a second plate body 122 connected to the first plate body 121, the second plate body 122 is arranged around the edge of the first plate body 121, the first plate body 121 separates the tube body 1 into multiple freezing sections A, and the second plate body 122 is used to close the side of the partial cavity 111 located in the freezing section A.

[0039] Specifically, the purpose of using the second plate 122 to seal the side of part of the cavity 111 in the freezing section A is to allow the nitrogen to be discharged along the cavity 111 of the spiral blade 11, so that the low-temperature nitrogen continues to freeze the stratum. In simple terms, when the low-temperature nitrogen rises, the low-temperature nitrogen in the freezing section A in the lower layer cannot directly enter the freezing section A in the upper layer from the tube body 1 due to the obstruction of the first plate 121, so the low-temperature nitrogen will enter the cavity 111 of the spiral blade 11. Under the obstruction of the second plate 122, the low-temperature nitrogen can only move along the cavity 111 around the outside of the second plate 122. Because the second plate 122 only seals part of the cavity 111, when the low-temperature nitrogen ascends to the unsealed cavity 111 area, part of the nitrogen will enter the freezing section A in the upper layer, and continue to rise after mixing with the low-temperature nitrogen in the freezing section A in the upper layer.

[0040] Furthermore, the height of the second plate 122 is 4 / 5 to 9 / 10 of the height of the freezing section A. In practical applications, the height of the second plate 122 can be 4 / 5 of the height of the freezing section A; it can also be 9 / 10 of the height of the freezing section A; the purpose is to close the sides of more cavities 111 in the freezing section A, so that the low-temperature nitrogen can move in the cavity 111, ensuring the freezing effect of the spiral blade 11.

[0041] Preferably, the first plate 121 is made of a heat insulating material. Considering that each freezing segment A can be independent of each other, the first plate 121 is made of a heat insulating material, which can avoid heat transfer between adjacent freezing segments A to a certain extent.

[0042] In this embodiment, there are two first partitions 12, which separate the tube body 1 into three freezing sections A, and there are three liquid supply pipes 2. In actual applications, the operator can increase the number of first partitions 12 and liquid supply pipes 2 according to actual conditions, but it is necessary to ensure that the number of freezing sections A matches the number of liquid supply pipes 2.

[0043] Furthermore, the bottom end of the liquid supply pipe 2 is closed, and a plurality of output holes 21 are provided on the side wall of the liquid supply pipe 2 near the bottom end thereof, and the plurality of output holes 21 form the output end of the liquid supply pipe 2. The liquid supply pipe 2 with a closed bottom end can ensure that the low-temperature nitrogen is uniformly output from the output end, and the heat exchange between the low-temperature nitrogen and the external soil can ensure the uniformity of freezing.

[0044] It should also be noted here that, in the present embodiment, the outer diameter of the tube body is 180 mm; the wall thickness of the tube body is 10 mm; the width of the spiral blade is 90 mm; the spacing between the spiral blades is 250 mm; the outer diameter of the liquid supply tube is 48 mm, the wall thickness of the liquid supply tube is 3.5 mm, and the aperture of the output hole on the side wall at the bottom end of the liquid supply tube is 6 mm.

[0045] Although the embodiments of the present application have been shown and described, those skilled in the art will appreciate that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present application, and that the scope of the present application is defined by the claims and their equivalents.

Claims

1. A ground freezing method using a long spiral freezer, characterized in that: The method relates to a long spiral freezer, which comprises a tube body, a spiral blade is arranged on the outside of the tube body, a cavity connected to the tube body is arranged inside the spiral blade, and a first partition and a second partition are arranged inside the tube body, wherein at least two first partitions and at least two second partitions are arranged; The first partition separates the tube body into a plurality of freezing sections; the second partition separates the tube body into a collecting section, the plurality of freezing sections are located between the collecting section and the bottom end of the tube body, and two adjacent freezing sections are connected through a cavity, and the collecting section is connected to its adjacent freezing section through a cavity; the tube body is provided with liquid supply pipes corresponding to the freezing sections one by one, and the second partition is provided with a collecting pipe connected to the collecting section; The method includes an active freezing stage and a maintenance freezing stage, and the method is specifically as follows: After the long spiral freezer is drilled into the formation, during the active freezing stage, liquid nitrogen is input into the liquid supply pipe, and the nitrogen discharged from the pipe body is collected through the collecting pipe, until the active freezing stage is over and the maintenance freezing stage begins; during the maintenance freezing stage, the liquid nitrogen input is stopped and brine is input into the liquid supply pipe for maintenance freezing, and the brine discharged from the pipe body is collected through the collecting pipe until the freezing is completed.

2. The ground freezing method according to claim 1, characterized in that: The temperature of the brine is -25°C to -28°C.

3. The ground freezing method according to claim 1, characterized in that: The long spiral freezer is drilled into the formation by a drilling rig, and all the spiral blades are located in the formation.

4. The ground freezing method according to claim 1, characterized in that: The first partition includes a first plate body arranged horizontally and a second plate body connected to the first plate body, the second plate body is arranged around the edge of the first plate body, the first plate body separates the tube body into multiple freezing sections, and the second plate body is used to close the side of the partial cavity located in the freezing section to block the connection between the tube body and the partial cavity.

5. The ground freezing method according to claim 4, characterized in that: The height of the second plate is 4 / 5 to 9 / 10 of the height of the freezing section.

6. The ground freezing method according to claim 4, characterized in that: The first plate body is a first plate body made of heat insulating material.

7. The ground freezing method according to claim 1, characterized in that: There are two first partitions, and the two first partitions separate the tube body into three freezing sections. There are three liquid supply pipes.

8. The ground freezing method according to claim 1, characterized in that: The bottom end of the liquid supply pipe is closed, and a plurality of output holes are arranged on the side wall of the liquid supply pipe near the bottom end, and the plurality of output holes form the output end of the liquid supply pipe.

Images