Freezer and vertical partial freezing process suitable for vertical partial freezing process

Abstract

The application discloses a freezing device and a vertical partial freezing process suitable for the vertical partial freezing process. The freezing device comprises a freezing tube, a liquid supply pipe and a liquid return pipe. The freezing tube is divided into a non-freezing section and a freezing section from top to bottom. One end of the liquid supply pipe extends into the bottom of the freezing section, and the other end of the liquid supply pipe extends out of the freezing tube from the non-freezing section. One end of the liquid return pipe extends into the bottom of the freezing section, and the other end of the liquid return pipe extends out of the freezing tube from the non-freezing section. The liquid supply pipe and the liquid return pipe are connected into one body at the bottom of the freezing section, and the liquid supply pipe and the liquid return pipe are in fluid communication. The low-temperature brine flows from the liquid supply pipe to the liquid return pipe. The non-freezing section is filled with air, and the freezing section is filled with clean water. The vertical partial freezing process is carried out by using the freezing device suitable for the vertical partial freezing process. The application solves the problems of poor heat insulation effect, complex structure and low cold energy utilization efficiency of the existing partial freezing device.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of vertical local freezing technology, in particular to a freezing device suitable for vertical local freezing process. BACKGROUND

[0002] There are mainly open excavation, underground excavation and shield construction methods in subway construction. The shield entering and exiting hole process in shield construction is the key process of tunnel construction by shield method, and there is a great risk in this construction link.

[0003] Before the shield enters and exits the hole, certain soil improvement measures need to be taken to make the soil outside the hole stable and self-supporting and have a certain strength. If it is not treated, when the stratum around the shield working well has poor self-stability and strong water permeability, such as loose sand or saturated water-containing clay layer, a large amount of soil and underground water will collapse into the working well after the hole is removed, resulting in large-area surface subsidence of the upper part of the hole, endangering the surrounding traffic roads, underground pipelines and buildings, and causing the shield machine to suddenly sink and "kowtow", deviate from the design axis, etc.

[0004] At present, the commonly used shield hole soil stability technology mainly includes dewatering, foundation reinforcement and freezing method. Freezing method is to freeze the water in the soil, and a frozen reinforced body with considerable strength is temporarily formed in the whole freezing range. Under the support of this reinforced body, the temporary wall at the hole is removed, the tunneling equipment enters the hole ring, the hole sealing device is installed, and the sealing performance is established before the hole is constructed.

[0005] The freezing method for reinforcing soil is widely used because of its good water stopping performance, resistance to part of water and soil pressure, flexible freezing form, strong adaptability, non-polluting construction, small influence on the surrounding environment and strong practicality.

[0006] At present, in the freezing construction scheme at home and abroad, it can be divided into three types according to the arrangement mode of the freezing pipe: (1) freezing scheme with vertical and inclined freezing pipes alternating with each other; (2) vertical freezing pipe freezing scheme; (3) horizontal freezing pipe freezing scheme. When the shield hole reinforcement of the subway does not have the condition to adopt the horizontal freezing scheme, the vertical freezing scheme can be adopted. According to the freezing range, the vertical freezing method can be divided into local freezing and full-depth freezing. The full-depth freezing mode of vertical freezing pipe is usually used in freezing reinforcement, and the local freezing mode is also widely used in engineering practice.

[0007] With the rapid development of subway construction, its trend is gradually developing to the deep space, and the subway tunnel is mostly located in the bustling city area, there are more buildings and facilities on the ground, at the same time, the complex pipeline is often buried in the upper stratum of the subway tunnel, and the influence of frost heaving and thawing settlement on the surrounding environment is larger. Therefore, under the above working conditions, the application of local freezing scheme can not only greatly reduce the refrigeration capacity, but also significantly reduce the frost heaving amount.

[0008] The existing local freezing adopts the following freezing devices: filling and pressurizing type, baffle type, filling salt water type and sleeve type. The common features of the above freezing device structures are: (1) the liquid supply pipe is a long pipe, and the liquid return pipe is a short pipe; (2) the liquid supply pipe and the liquid return pipe are straight pipes, and they are independent and not connected; (3) the refrigerant in the freezing device is salt water.

[0009] The advantages of the filling and pressurizing type are: good heat insulation effect, simple structure and easy to realize; the disadvantages are: the need for pressurization, and the pressurization needs to be controlled according to the required pressure, otherwise the use effect will be reduced. The heat insulation effect of the baffle type is close to that of the filling and pressurizing type, but the processing requirement of the baffle is strict, and the lower liquid supply pipe is more troublesome. The heat insulation effect of the filling salt water type is poor, and the expansion speed of the frozen soil in the non-freezing section is 40-50% of that in the freezing section. The heat insulation effect of the sleeve type is close to that of the filling and pressurizing type, but the structure is complex, the processing requirement is strict, and it is not easy to realize. SUMMARY

[0010] Therefore, the technical problem to be solved by the present application is to provide a freezing device suitable for vertical local freezing process, so as to solve the problems of poor heat insulation effect, complex structure and low utilization efficiency of local freezing cold capacity of the existing local freezing device.

[0011] To solve the above technical problems, the present application provides the following technical scheme:

[0012] The freezing device suitable for vertical local freezing process comprises a freezing tube, a liquid supply pipe and a liquid return pipe; the freezing tube is divided into a non-freezing section H1 and a freezing section H2 from top to bottom; one end of the liquid supply pipe extends into the bottom of the freezing section H2, and the other end of the liquid supply pipe extends out of the freezing tube from the non-freezing section H1; one end of the liquid return pipe extends into the bottom of the freezing section H2, and the other end of the liquid return pipe extends out of the freezing tube from the non-freezing section H1; the liquid supply pipe and the liquid return pipe are in fluid communication at the bottom of the freezing section H2, that is, the two are connected as a whole

Compared with the traditional liquid supply pipe and liquid return pipe which are independent of each other, the liquid supply pipe and the liquid return pipe are designed as a whole in the application, so that the flow rate of the internal brine can be improved, thereby accelerating the speed of absorbing the heat of the surrounding rock and improving the heat conduction efficiency

The application uses "low-temperature brine + clear water" as the refrigerant, that is, the internal part of the liquid supply pipe and the liquid return pipe is low-temperature brine, and the part between the liquid supply pipe, the liquid return pipe and the freezing tube is clear water; the part between the liquid supply pipe and the freezing tube is clear water, which will gradually freeze into ice in the process of heat conduction with the low-temperature brine in the liquid supply pipe, and the heat conduction coefficient and the heat diffusion coefficient of ice are much higher than those of the low-temperature brine in the freezing device used in the traditional local freezing process, thereby significantly shortening the active freezing time and greatly reducing the construction cost

[0013] The freezing device suitable for vertical local freezing process, the liquid supply pipe comprises a straight pipe and a coil pipe; the straight pipe is located in the non-freezing section H1, the coil pipe is located in the freezing section H2, and the straight pipe and the coil pipe are in fluid communication; the lower end of the coil pipe is connected with the lower end of the liquid return pipe as a whole, and the coil pipe and the liquid return pipe are in fluid communication.

[0014] The freezing device suitable for vertical local freezing process, the coil pipe has a cylindrical spiral spring structure, a conical spiral spring structure or a parabolic spiral spring structure; compared with the straight pipe structure, the cylindrical spiral spring structure, the conical spiral spring structure or the parabolic spiral spring structure can significantly increase the heat dissipation area of the liquid supply pipe and the circulating distance and time of the internal brine, thereby improving the heat exchange effect.

[0015] The freezing device suitable for vertical local freezing process, the coil pipe spirals around the liquid return pipe.

[0016] The outer diameter of the conical spiral spring structure gradually decreases or increases from top to bottom.

[0017] The outer diameter of the parabolic spiral spring structure gradually decreases or increases from top to bottom.

[0018] The return pipe is a straight-through pipe.

[0019] The freezing device for the vertical local freezing process further comprises a water injection pipe, one end of the water injection pipe extends into the non-freezing section H1, and the other end of the water injection pipe extends out of the freezing pipe from the non-freezing section H1. The water injection pipe is made of iron pipe, and the main function of the water injection pipe is to inject clean water into the freezing section H2 before freezing.

[0020] The freezing device for the vertical local freezing process further comprises a perforated plate, the perforated plate is installed on the pipe opening of the freezing pipe, and the diameter of the perforated plate is greater than or equal to the inner diameter of the freezing pipe; or the perforated plate is installed on the inner wall of the freezing pipe in the non-freezing section H1, and the diameter of the perforated plate is less than or equal to the inner diameter of the freezing pipe.

[0021] The vertical local freezing process is performed by using the freezing device for the vertical local freezing process.

[0022] In the present application, the freezing pipe is made of low-carbon seamless steel pipe, and the liquid supply pipe and the return pipe are made of steel pipe.

[0023] The technical scheme of the present application has the following beneficial technical effects:

[0024] The freezing device for the vertical local freezing process disclosed in the present application has the advantages of simple structure, good heat insulation effect, greatly reduced refrigeration capacity for local freezing, improved heat exchange efficiency, effectively prevented adverse effects of frost heaving and thaw settlement on the surrounding environment, and effectively protected surrounding environment. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 FIG. 1 is a structural schematic diagram of a freezing device for a vertical local freezing process according to an embodiment of the present application;

[0026] Figure 2 FIG. 2 is a structural schematic diagram of another freezing device for a vertical local freezing process according to an embodiment of the present application;

[0027] Figure 3 Schematic diagram of a conical helical spring (outer diameter gradually decreases from top to bottom);

[0028] Figure 4 Schematic diagram of a conical helical spring (outer diameter gradually increases from top to bottom);

[0029] Figure 5 Schematic diagram of a parabolic helical spring.

[0030] The reference numerals in the diagram are as follows: 1-supply pipe; 2-return pipe; 3-water injection pipe; 4-air; 5-freezing pipe; 6-clean water; 7-coil; 8-with perforated plate; 9-straight pipe; H1-non-freezing section; H2-freezing section. Detailed Implementation

[0031] Example 1

[0032] like Figure 1 As shown, the freezer applicable to the vertical partial freezing process in this embodiment includes a freezing tube 5, a liquid supply tube 1, a liquid return tube 2, a water injection tube 3, and a perforated plate 8. The freezing tube 5 is divided into a non-freezing section H1 and a freezing section H2 from top to bottom. One end of the liquid supply tube 1 extends into the bottom of the freezing section H2, and the other end of the liquid supply tube 1 extends out of the freezing tube 5 from the non-freezing section H1. One end of the liquid return tube 2 extends into the bottom of the freezing section H2, and the other end of the liquid return tube 2 extends out of the freezing tube 5 from the non-freezing section H1. The other end extends out of the freezing pipe 5 from the non-freezing section H1; the supply pipe 1 and the return pipe 2 are fluidly connected at the bottom of the freezing section H2; low-temperature brine flows from the supply pipe 1 to the return pipe 2; the non-freezing section H1 is filled with air 4, and the freezing section H2 is filled with clean water 6; one end of the water injection pipe 3 extends into the non-freezing section H1, and the other end of the water injection pipe 3 extends out of the freezing pipe 5 from the non-freezing section H1; the perforated plate 8 is installed at the opening of the freezing pipe 5, and the diameter of the perforated plate 8 is greater than or equal to the inner diameter of the freezing pipe 5. The perforated plate 8 is equivalent to the cover plate at the top of the freezing pipe, which can prevent debris from falling into the freezing pipe. The cover plate is made of iron plate.

[0033] The supply pipe 1 includes a straight pipe 9 and a coil 7; the straight pipe 9 is located in the non-freezing section H1, and the coil 7 is located in the freezing section H2, with the straight pipe 9 and the coil 7 in fluid communication; the lower end of the coil 7 is connected to the lower end of the return pipe 2 as a single unit, with the coil 7 and the return pipe 2 in fluid communication; the return pipe 2 is a straight pipe, and the coil 7 has a cylindrical helical spring structure; the coil 7 spirals around the return pipe 2.

[0034] In some other embodiments, the perforated plate 8 can also be installed on the inner wall of the freezing pipe 5 in the non-frozen section H1, and the diameter of the perforated plate 8 is less than or equal to the inner diameter of the freezing pipe 5

as shown

[0035] The freezing device of the present embodiment has good heat insulation effect of the freezing section and the non-frozen section, and the average expansion speed of the frozen soil in the non-frozen section is only about 10% of that in the freezing section. Compared with the prior art, the refrigerating capacity is greatly reduced, and the heat exchange efficiency is significantly improved.

[0036] In some other embodiments, the coil pipe with a conical spiral spring structure can be used instead of the coil pipe with a cylindrical spiral spring structure in the present embodiment, and the heat insulation effect of the freezing device can also be comparable to that of the present embodiment. The refrigerating capacity is reduced and the heat exchange efficiency is improved compared with the prior art. However, compared with the present embodiment, if the outer diameter of the coil pipe with a conical spiral spring structure gradually decreases from top to bottom

see Figure 3

see Figure 4

[0037] In some other embodiments, the coil pipe with a parabolic spiral spring structure

see FIG. 5

[0038] In addition, in some other embodiments, the liquid return pipe can also be a coil pipe with a cylindrical spiral spring structure, a conical spiral spring structure, or a parabolic spiral spring structure. In this case, the freezing device can also have a heat insulation effect comparable to that of the present embodiment. The refrigerating capacity is reduced and the heat exchange efficiency is improved compared with the prior art. Compared with the present embodiment, the refrigerating capacity reduction and the heat exchange efficiency improvement are higher than those of the present embodiment. However, if the liquid return pipe is also replaced by a coil pipe with a cylindrical spiral spring structure, a conical spiral spring structure, or a parabolic spiral spring structure instead of a straight pipe, the manufacturing and installation difficulty will increase, and the power of the brine pump also needs to be increased.

[0039] Embodiment 2

[0040] ​The vertical partial freezing process of the embodiment is to freeze partially by using the freezing device suitable for the vertical partial freezing process of the embodiment 1, and the specific process flow is as follows:

[0041] Before the partial freezing is performed, the freezing tube in the embodiment 1 is first lowered to the corresponding stratum position, and the liquid supply pipe 1, the liquid return pipe 2, the water injection pipe 3 and the perforated plate 8 are assembled according to the structure of the freezing device in the embodiment 1. According to the partial freezing height, the water injection pipe 3 is used to inject clean water into the freezing tube, so as to divide the freezing tube into the freezing section H2 and the non-freezing section H1. The low-temperature brine is input into the liquid supply pipe 1, and the low-temperature brine flows from the straight pipe 9 of the liquid supply pipe 1 to the coil pipe 7, and then flows to the liquid return pipe 2 and then flows out of the freezing device. In this process, as the low-temperature brine in the liquid supply pipe 1 continuously flows in and the high-temperature brine in the liquid return pipe 2 continuously flows out, the clean water exchanges heat with the low-temperature brine and gradually freezes into ice. The thermal conductivity coefficient and the thermal diffusion coefficient of the ice are much higher than those of the low-temperature brine in the freezing device used in the conventional partial freezing process, so that the active freezing time is significantly shortened, and the construction cost can be greatly reduced. Since the space above the water surface of the clean water is air, the thermal conductivity coefficient of the air is much lower than that of the ice, so that the non-freezing section above the water surface of the clean water and the freezing section below the water surface of the clean water have good heat insulation effect, thereby avoiding the frost heaving of the stratum in the non-freezing section. At the same time, the free space above the clean water provides a large enough space for the volume expansion of the ice after the ice is formed, so as to prevent the damage of the ice heaving force to the freezing tube. When the partial freezing is completed and the freezing tube is pulled out, the hot brine is circulated in the liquid supply pipe 1 and the liquid return pipe 2, so as to melt the frozen soil around the freezing tube 5 by about 100 mm, thereby easily completing the pulling operation of the freezing tube 5.

[0042] Obviously, the above embodiments are only examples for clearly illustrating the present application, and are not intended to limit the embodiments. Based on the above description, other different forms of changes or variations can be made by those skilled in the art. Here, all the embodiments are not required to be exhausted, and the obvious changes or variations derived therefrom are still within the protection scope of the claims of the present application.

Claims

1. A freezer suitable for use in a vertical partial freezing process, characterised in that, The freezing tube (5), the liquid supply pipe (1) and the liquid return pipe (2); the freezing tube (5) is divided into non-freezing section H1 and freezing section H2 from top to bottom; one end of the liquid supply pipe (1) extends into the bottom of the freezing section H2, the other end of the liquid supply pipe (1) extends out of the freezing tube (5) from the non-freezing section H1; one end of the liquid return pipe (2) extends into the bottom of the freezing section H2, the other end of the liquid return pipe (2) extends out of the freezing tube (5) from the non-freezing section H1; the liquid supply pipe (1) and the liquid return pipe (2) are fluidly connected at the bottom of the freezing section H2; the low-temperature saline water flows from the liquid supply pipe (1) to the liquid return pipe (2); the non-freezing section H1 is filled with air (4), and the freezing section H2 is filled with clean water (6); the liquid supply pipe (1) comprises a straight pipe (9) and a coil pipe (7); the straight pipe (9) is located in the non-freezing section H1, the coil pipe (7) is located in the freezing section H2, and the straight pipe (9) and the coil pipe (7) are fluidly connected; the lower end of the coil pipe (7) is connected to the lower end of the liquid return pipe (2) as a whole, and the coil pipe (7) and the liquid return pipe (2) are fluidly connected; The coil pipe (7) has a cylindrical spiral spring structure, a conical spiral spring structure or a parabolic spiral spring structure; the coil pipe (7) spirals around the liquid return pipe (2).

2. The freezer suitable for vertical partial freezing process according to claim 1, characterized in that, The outer diameter of the conical spiral spring structure gradually decreases or increases from top to bottom.

3. The freezer suitable for vertical partial freezing process according to claim 1, characterized in that, The outer diameter of the parabolic spiral spring structure gradually decreases or increases from top to bottom.

4. A freezer suitable for use in a vertical partial freezing process according to any one of claims 1-3, characterized in that, The liquid return pipe (2) is a straight-through pipe.

5. The freezer suitable for vertical partial freezing process according to any one of claims 1-3, characterized in that, It also includes a water injection pipe (3); one end of the water injection pipe (3) extends into the non-freezing section H1, and the other end of the water injection pipe (3) extends out of the freezing tube (5) from the non-freezing section H1.

6. The freezer suitable for vertical partial freezing process according to any one of claims 1-3, characterized in that, It also includes a perforated plate (8); the perforated plate (8) is installed on the pipe opening of the freezing tube (5), and the diameter of the perforated plate (8) is greater than or equal to the inner diameter of the freezing tube (5); or the perforated plate (8) is installed on the inner wall of the freezing tube (5) in the non-freezing section H1, and the diameter of the perforated plate (8) is less than or equal to the inner diameter of the freezing tube (5).

7. A vertical partial freeze process characterized by, The freezing device suitable for vertical partial freezing process is used for vertical partial freezing.

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