Liquid nitrogen-liquid carbon dioxide combined stratum freezing system

Abstract

The invention discloses a liquid nitrogen-liquid carbon dioxide combined stratum freezing system which comprises a liquid carbon dioxide freezing mechanism and a liquid nitrogen cooling mechanism, the liquid carbon dioxide freezing mechanism comprises a carbon dioxide circulating pipeline, and a liquid nitrogen structure comprises a nitrogen storage tank, a liquid nitrogen conveying pipe and an exhaust pipe which are connected and matched with one another. The control device can control the liquid nitrogen cooling mechanism to work and convey liquid nitrogen into the freezing pipe so that the stratum can be rapidly cooled, and then control the liquid carbon dioxide freezing mechanism to work and convey liquid carbon dioxide into the freezing pipe so that the carbon dioxide can be recycled so that the stratum can be rapidly frozen. Therefore, the liquid carbon dioxide freezing mechanism and the liquid nitrogen cooling mechanism are combined to cool and freeze the stratum, the cooling and freezing efficiency can be effectively improved, and meanwhile the cost of freezing by independently using liquid nitrogen is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of ground freezing, and in particular to a ground freezing system. Background Art

[0002] Ground freezing refers to a special civil engineering construction method that uses artificial refrigeration technology to turn natural soil into artificial frozen soil, thereby improving the soil properties to facilitate subsequent underground engineering construction.

[0003] A Chinese patent with announcement number CN 214573874 U discloses an artificial ground freezing system using low-temperature carbon dioxide circulation refrigeration, including: freezing pipes, which are installed in the area where freezing construction is required; a liquid carbon dioxide supply device, which is connected to all the freezing pipes and forms a first circulation loop, and liquid carbon dioxide is continuously supplied into the freezing pipes through the liquid carbon dioxide supply device. The liquid carbon dioxide in the freezing pipes is used to freeze the soil around the freezing pipes to complete the freezing construction of the corresponding area in the formation, so as to recycle carbon dioxide and achieve more efficient freezing at the same cost.

[0004] However, the freezing system provided by the above scheme has a long freezing period for the stratum and cannot quickly cool the stratum. In addition, in the prior art, brine freezing and liquid nitrogen freezing are usually used to freeze the stratum. The cost of brine freezing is low, but the efficiency is also low. Although liquid nitrogen freezing is efficient, the cost is also high.

[0005] Therefore, how to effectively and quickly cool the ground, improve the efficiency of ground freezing, and reduce costs has become an urgent problem to be solved in this field. Summary of the invention

[0006] In view of the defects of the prior art, the object of the present invention is to provide a liquid nitrogen-liquid carbon dioxide combined ground freezing system with fast cooling speed, high ground freezing efficiency and low cost.

[0007] In order to achieve the above-mentioned purpose, the liquid nitrogen-liquid carbon dioxide combined ground freezing system provided by the present invention is used to cooperate with the freezing zone of the ground, wherein the freezing zone is provided with a freezing pipe, including a liquid carbon dioxide freezing mechanism, wherein the liquid carbon dioxide freezing mechanism includes a carbon dioxide circulation pipeline, and further includes

[0008] A liquid nitrogen cooling mechanism, the liquid nitrogen cooling mechanism comprising a liquid nitrogen storage tank, a liquid nitrogen delivery pipe and an exhaust pipe, one end of the liquid nitrogen delivery pipe is connected to the liquid nitrogen storage tank, the other end is connected to the freezing pipe, and the exhaust pipe is connected to the freezing pipe.

[0009] A control device is configured to control the working states of the liquid carbon dioxide freezing mechanism and the liquid nitrogen cooling mechanism.

[0010] Furthermore, the liquid nitrogen delivery pipe includes a liquid nitrogen main pipe and a liquid nitrogen branch pipe, one end of the liquid nitrogen main pipe cooperates with the liquid nitrogen storage tank, and the other end is connected to the liquid nitrogen branch pipe, and the liquid nitrogen branch pipe is built in the freezing pipe.

[0011] Furthermore, a liquid nitrogen outlet is provided at the bottom end of the liquid nitrogen storage tank, the liquid nitrogen outlet is connected to the input end of a liquid nitrogen pump, and the output end of the liquid nitrogen pump is connected to the liquid nitrogen main conduit.

[0012] Furthermore, the end of the liquid nitrogen main conduit is connected to the liquid nitrogen branch pipe through a first valve.

[0013] Furthermore, the exhaust pipe includes an exhaust main pipe and an exhaust branch pipe, the exhaust main pipe is arranged above the liquid nitrogen main pipe, one end of the exhaust branch pipe is connected to the exhaust main pipe, and the other end is arranged on the top of the freezing pipe.

[0014] Furthermore, the end of the exhaust branch pipe is connected to the freezing pipe through a second valve.

[0015] Furthermore, the control device is configured to control the interlocking of the working states of the liquid nitrogen cooling mechanism and the liquid carbon dioxide freezing mechanism.

[0016] The liquid nitrogen-liquid carbon dioxide combined ground freezing system provided by the present invention comprises a liquid carbon dioxide freezing mechanism and a liquid nitrogen cooling mechanism, wherein the liquid carbon dioxide freezing mechanism comprises a carbon dioxide circulation pipeline, and the liquid nitrogen structure comprises a nitrogen storage tank, a liquid nitrogen delivery pipe and an exhaust pipe which are connected and matched with each other, so that a control device can control the liquid nitrogen cooling mechanism to work, deliver liquid nitrogen to the freezing pipe, so that the ground can be quickly cooled, and then control the liquid carbon dioxide freezing mechanism to work, deliver liquid carbon dioxide to the freezing pipe, and circulate the carbon dioxide to freeze the ground quickly, so that the ground is cooled and frozen respectively by the liquid carbon dioxide freezing mechanism and the liquid nitrogen cooling mechanism, which can effectively improve the cooling and freezing efficiency, and reduce the cost of freezing by using liquid nitrogen alone. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments.

[0018] Figure 1 The overall structural schematic diagram of the liquid nitrogen-liquid carbon dioxide combined ground freezing system provided by the present invention;

[0019] Figure 2 It is a schematic diagram of the enlarged structure of the freezing zone of the present invention;

[0020] Figure 3 For the present invention Figure 2 The enlarged structural diagram at A in the middle;

[0021] Figure 4It is a schematic diagram of the enlarged structure of the liquid nitrogen storage tank of the present invention;

[0022] Figure 5 It is a schematic diagram of the enlarged structure of the carbon dioxide liquefier of the present invention;

[0023] Figure 6 It is a schematic diagram of the enlarged structure of the condenser of the present invention.

[0024] Reference numerals:

[0025] 1. Freezing area; 2. Freezing pipe;

[0026] 100. Liquid carbon dioxide freezing mechanism; 110. Carbon dioxide circulation pipeline; 120. Carbon dioxide pump; 121. Carbon dioxide delivery pipe; 130. Carbon dioxide liquefier; 131. Liquefaction pipe; 140. Compressor; 150. Condenser; 151. Condenser pipe; 160. Cooling tower;

[0027] 200. Liquid nitrogen cooling mechanism; 210. Liquid nitrogen storage tank; 211. Liquid nitrogen outlet; 212. Liquid nitrogen pump; 220. Liquid nitrogen delivery pipe; 221. Liquid nitrogen main pipe; 222. Liquid nitrogen branch pipe; 223. First valve; 230. Exhaust pipe; 231. Exhaust main pipe; 232. Exhaust branch pipe; 233. Second valve. DETAILED DESCRIPTION

[0028] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention is further explained below with reference to specific diagrams.

[0029] See also Figure 1 , which shows an example of the liquid nitrogen-liquid carbon dioxide combined stratum freezing system provided by the present invention.

[0030] As can be seen from the figure, the liquid nitrogen-liquid carbon dioxide combined stratum freezing system of this example is used to cooperate with the freezing zone 1 of the stratum. A freezing pipe 2 is provided in the freezing zone 1. The freezing system includes a carbon dioxide freezing mechanism 100, a liquid nitrogen cooling mechanism 200 and a control device.

[0031] The liquid carbon dioxide freezing mechanism 100 includes a carbon dioxide circulation pipeline, and the liquid nitrogen cooling mechanism 200 includes a liquid nitrogen storage tank 210, a liquid nitrogen delivery pipe 220 and an exhaust pipe 230. One end of the liquid nitrogen delivery pipe 220 is connected to the liquid nitrogen storage tank 210, and the other end is connected to the freezing pipe 2. The exhaust pipe 230 is connected to the freezing pipe 2.

[0032] Furthermore, the control device is configured to control the working states of the liquid carbon dioxide freezing mechanism 100 and the liquid nitrogen cooling mechanism 200, so that the control device controls the liquid nitrogen cooling mechanism 200 to transport liquid nitrogen to the freezing pipe 2 to quickly cool the formation, and then controls the liquid carbon dioxide freezing mechanism 100 to circulate liquid carbon dioxide to the freezing pipe 2 to quickly freeze the formation, thereby the liquid carbon dioxide freezing mechanism 100 and the liquid nitrogen cooling mechanism 200 are combined to cool and freeze the formation respectively, so as to improve the cooling and freezing efficiency and reduce costs at the same time.

[0033] Among them, combined Figures 1 to 4 The liquid nitrogen delivery pipe 220 of the liquid nitrogen cooling mechanism 200 includes a liquid nitrogen main pipe 221 and a liquid nitrogen branch pipe 222. The input end of the liquid nitrogen main pipe 221 cooperates with the liquid nitrogen storage tank 210, and the output ends are respectively connected to the liquid nitrogen branch pipes 222, and the liquid nitrogen branch pipes 222 are respectively built in the freezing pipes 2, so that the liquid nitrogen in the liquid nitrogen storage tank 210 can be transported to the liquid nitrogen branch pipes 222 through the liquid nitrogen main pipe 221, and then transported to the freezing pipe 2 through the liquid nitrogen branch pipes 222, thereby cooling the formation.

[0034] Furthermore, combined with Figure 4 A liquid nitrogen outlet 211 is provided at the bottom of the liquid nitrogen storage tank 210, and the liquid nitrogen outlet 211 is connected to the input end of a liquid nitrogen pump 212, and the output end of the liquid nitrogen pump 212 is connected to the input end 221 of the liquid nitrogen main conduit. The liquid nitrogen pump 212 is also connected to a control device, so that the control device can start the liquid nitrogen pump 212, so that the liquid nitrogen pump 212 can extract liquid nitrogen from the liquid nitrogen outlet 211 of the liquid nitrogen storage tank 210 and output it to the liquid nitrogen main conduit 221, thereby improving the transportation efficiency of liquid nitrogen.

[0035] Combination Figure 2 and Figure 3 In order to control the delivery flow rate of liquid nitrogen, a first valve 223 is provided at the end where the liquid nitrogen main conduit 221 and the liquid nitrogen branch pipe 222 cooperate. The first valve 223 is connected to the control device, so that the control device can open the first valve 223 and control the opening of the first valve 223, so that the liquid nitrogen can stably enter the liquid nitrogen branch pipe 222 from the liquid nitrogen main conduit 221, and enter the freezing pipe 2 through the liquid nitrogen branch pipe 222, so that the liquid nitrogen is directly vaporized in the freezing pipe 2, and the latent heat of vaporization and the sensible heat of temperature rise of the liquid nitrogen are used to achieve refrigeration, absorb the heat in the formation, and achieve rapid cooling of the formation.

[0036] Combination Figures 1 to 4Furthermore, the liquid nitrogen cooling mechanism 200 also includes an exhaust pipe 230, which includes an exhaust main pipe 231 and an exhaust branch pipe 232. The exhaust main pipe 232 is arranged above the liquid nitrogen main pipe 221. One end of the exhaust branch pipe 232 is connected to the exhaust main pipe 231, and the other end is arranged on the top of the freezing pipe 2, so that the nitrogen generated by the vaporization of liquid nitrogen in the freezing pipe 2 can be discharged into the exhaust branch pipe 232, and flow into the exhaust main pipe 231 from the exhaust branch pipe 232, and finally discharged from the exhaust main pipe 231 to the atmosphere to balance the pressure in the freezing pipe 2.

[0037] Combination Figure 2 and Figure 3 In order to control the nitrogen discharge flow rate generated by the vaporization of liquid nitrogen and effectively balance the pressure of the freezing pipe 2, a second valve 233 is provided at the end of the exhaust branch pipe 232 that cooperates with the freezing pipe 2. The second valve 233 is connected to the control device, so that the control device can open the second valve 233 and control the opening of the second valve 233, so that the nitrogen can stably enter the exhaust main pipe 232 from the exhaust branch pipe 232 and be discharged through the exhaust main pipe 232.

[0038] At the same time, the exhaust main pipe 232 is arranged above the liquid nitrogen main pipe 221, which can ensure that the liquid nitrogen can be smoothly discharged from the freezing pipe 2 after vaporization, so as to prevent the liquid nitrogen from re-liquefying after vaporization, thereby avoiding the accumulation of liquid nitrogen in the freezing pipe 2 and balancing the pressure in the freezing pipe 2, thereby improving the working efficiency of the liquid nitrogen cooling mechanism 200 and ensuring that the formation can be cooled quickly.

[0039] Since the cost of using liquid nitrogen alone to cool and freeze the formation is relatively high, the freezing system also includes a liquid carbon dioxide freezing mechanism 100, so that after the liquid nitrogen cooling mechanism 200 quickly cools the formation, the liquid carbon dioxide freezing mechanism 100 can transport liquid carbon dioxide to the freezing pipe 2 to quickly freeze the formation, and recycle the carbon dioxide, thereby improving freezing efficiency and reducing costs.

[0040] Combination Figure 1 Specifically, the liquid carbon dioxide freezing mechanism 100 includes a carbon dioxide circulation pipeline 110, on which a carbon dioxide pump 120, a carbon dioxide liquefier 130, a compressor 140, a condenser 150 and a cooling tower 160 are respectively provided, so that low-temperature liquid carbon dioxide can enter the freezing pipe 2 through the carbon dioxide pump 120 to freeze the formation, and the heated carbon dioxide then enters the carbon dioxide liquefier 130, the compressor 140, the condenser 150 and the cooling tower 160 in turn to be cooled, and then enters the freezing pipe 2 again to freeze the formation, so as to recycle the carbon dioxide.

[0041] Furthermore, the carbon dioxide pump 120 is respectively connected to the freezing pipe 2 and the carbon dioxide liquefier 130 through the carbon dioxide delivery pipe 121, so that the carbon dioxide pump 120 delivers low-temperature liquid carbon dioxide to the freezing pipe 2 through the carbon dioxide delivery pipe 121. The liquid carbon dioxide quickly absorbs heat and vaporizes into carbon dioxide gas in the freezing pipe 2, causing the formation to freeze quickly.

[0042] At the same time, the carbon dioxide gas will flow into the carbon dioxide liquefier 130 through the carbon dioxide delivery pipe 121, so that the carbon dioxide liquefier 130 converts the gaseous carbon dioxide into liquid carbon dioxide.

[0043] Combination Figure 5 and Figure 6 In coordination therewith, the output end of the liquefaction pipe 131 in the carbon dioxide liquefier 130 is connected to the input end of the compressor 140, the output end of the compressor 140 is connected to the input end of the condenser 150, a condenser pipe 151 is provided inside the condenser 150, the output end of the condenser pipe 151 is connected to the input end of the cooling tower 160, so that the carbon dioxide liquefier 130, the compressor 140, the condenser 150 and the cooling tower 160 are connected to form a circulation pipeline, the liquid carbon dioxide flows in the circulation pipeline to be pressurized and cooled respectively, and then enters the freezing pipe 2 again through the carbon dioxide pump 120, thereby recycling the carbon dioxide and continuously freezing the formation to improve the freezing efficiency.

[0044] In order to control the working state of the freezing system, the control device is configured to connect the liquid nitrogen pump 212, the first valve 223 and the second valve 233 of the liquid nitrogen cooling mechanism 200 and the liquid carbon dioxide freezing mechanism 100, so as to control the working states of the liquid nitrogen cooling mechanism 200 and the liquid carbon dioxide freezing mechanism 100 respectively, and control the working states of the liquid nitrogen cooling mechanism 200 and the liquid carbon dioxide freezing mechanism 100 to be interlocked, so that the liquid nitrogen cooling mechanism 200 and the liquid carbon dioxide freezing mechanism 100 can jointly cool and freeze the formation respectively.

[0045] Specifically, in the cooling stage, the control device turns on the liquid nitrogen pump 212, the first valve 223 and the second valve 233 to stably transport liquid nitrogen and quickly cool down the formation. After the cooling is completed, in the freezing stage, the control device turns off the liquid nitrogen pump 212, the first valve 223 and the second valve 233, and turns on the liquid carbon dioxide freezing mechanism 100 to stably transport liquid carbon dioxide and quickly freeze the formation, thereby improving the cooling and freezing efficiency of the formation and reducing the cost of using liquid nitrogen alone for freezing.

[0046] Here, the control device may be constituted by a control cabinet or a remote controller.

[0047] The following examples illustrate the working process of the present invention in a specific application. It should be noted that the following content is only a specific application example of the present solution and does not constitute a limitation to the present solution.

[0048] First, in the cooling stage, the control device turns on the liquid nitrogen pump 212, the first valve 223 and the second valve 233 of the liquid nitrogen cooling mechanism 200, so that the liquid nitrogen pump 212 can extract liquid nitrogen from the liquid nitrogen outlet 211 of the liquid nitrogen storage tank 210, and output it to the liquid nitrogen main conduit 221, and then the liquid nitrogen can be transported to the liquid nitrogen branch pipe 222 through the liquid nitrogen main conduit 221 and the first valve 223, and finally transported to the freezing pipe 2 through the liquid nitrogen branch pipe 222, so as to quickly cool the formation.

[0049] In the freezing stage, the control device turns off the liquid nitrogen pump 212, the first valve 223 and the second valve 233 of the liquid nitrogen cooling mechanism 200, and turns on the liquid carbon dioxide freezing mechanism 100, so that the low-temperature carbon dioxide can enter the freezing pipe 2 through the carbon dioxide pump 120 to quickly freeze the formation. The heated carbon dioxide then enters the carbon dioxide liquefier 130, the compressor 140, the condenser 150 and the cooling tower 160 in sequence to cool down, and then enters the freezing pipe 2 again to recycle the carbon dioxide and quickly freeze the formation.

[0050] The real-time temperature of the freezing tube 2 is detected by a temperature sensor so that the liquid carbon dioxide freezing mechanism 100 is automatically switched when the temperature drops beyond a temperature drop threshold, thereby facilitating precise control of the linkage between the carbon dioxide system and the liquid nitrogen system.

[0051] The liquid nitrogen-liquid carbon dioxide combined ground freezing system provided by the present invention realizes the linkage between the liquid nitrogen cooling mechanism 200 and the carbon dioxide freezing mechanism 100 to cool and freeze the ground respectively through the cooperation of the carbon dioxide freezing mechanism 100, the liquid nitrogen cooling mechanism 200 and the control device, thereby improving the cooling and freezing efficiency of the ground and reducing the cost of freezing by liquid nitrogen alone.

[0052] The above shows and describes the basic principles, main features and advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A liquid nitrogen-liquid carbon dioxide combined ground freezing system, used to cooperate with the freezing zone of the ground, wherein the freezing zone is provided with a freezing pipe, including a liquid carbon dioxide freezing mechanism, wherein the liquid carbon dioxide freezing mechanism includes a carbon dioxide circulation pipeline, characterized in that: Also includes A liquid nitrogen cooling mechanism, the liquid nitrogen cooling mechanism comprising a liquid nitrogen storage tank, a liquid nitrogen delivery pipe and an exhaust pipe, one end of the liquid nitrogen delivery pipe is connected to the liquid nitrogen storage tank, the other end is connected to the freezing pipe, and the exhaust pipe is connected to the freezing pipe. A control device is configured to control the working states of the liquid carbon dioxide freezing mechanism and the liquid nitrogen cooling mechanism.

2. The liquid nitrogen-liquid carbon dioxide combined ground freezing system according to claim 1, characterized in that: The liquid nitrogen delivery pipe comprises a liquid nitrogen main pipe and a liquid nitrogen branch pipe. One end of the liquid nitrogen main pipe cooperates with the liquid nitrogen storage tank, and the other end is connected to the liquid nitrogen branch pipe. The liquid nitrogen branch pipe is built in the freezing pipe.

3. The liquid nitrogen-liquid carbon dioxide combined ground freezing system according to claim 2, characterized in that: A liquid nitrogen outlet is provided at the bottom end of the liquid nitrogen storage tank, the liquid nitrogen outlet is connected to the input end of a liquid nitrogen pump, and the output end of the liquid nitrogen pump is connected to the liquid nitrogen main conduit.

4. The liquid nitrogen-liquid carbon dioxide combined ground freezing system according to claim 2, characterized in that: The end of the liquid nitrogen main conduit is connected to the liquid nitrogen branch pipe through a first valve.

5. The liquid nitrogen-liquid carbon dioxide combined ground freezing system according to claim 2, characterized in that: The exhaust pipe comprises an exhaust main pipe and an exhaust branch pipe. The exhaust main pipe is arranged above the liquid nitrogen main pipe. One end of the exhaust branch pipe is connected to the exhaust main pipe, and the other end is arranged on the top of the freezing pipe.

6. The liquid nitrogen-liquid carbon dioxide combined ground freezing system according to claim 5, characterized in that: The end of the exhaust branch pipe is connected to the freezing pipe through a second valve.

7. The liquid nitrogen-liquid carbon dioxide combined ground freezing system according to claim 1, characterized in that: The control device is configured to control the interlocking of the working states of the liquid nitrogen cooling mechanism and the liquid carbon dioxide freezing mechanism.

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