Stratum freezing system and method based on solid and liquid carbon dioxide

Abstract

The invention discloses a stratum freezing system and method based on solid and liquid carbon dioxide, the solid carbon dioxide is sublimated to absorb heat by adopting a heat exchange cooling mechanism to form a primary refrigerant, and then the liquid carbon dioxide is conveyed through a carbon dioxide conveying mechanism, so that the liquid carbon dioxide exchanges heat with the primary refrigerant to form a secondary refrigerant; a compressor and other devices are not needed to reduce the temperature of the primary refrigerant, the solid carbon dioxide is directly used for sublimating and absorbing heat to cool the liquid carbon dioxide, so that the freezing period is shortened, the temperature of the primary refrigerant is greatly reduced due to the characteristics of the solid carbon dioxide, and the freezing temperature of the secondary refrigerant can be effectively reduced; the circulating mechanism conveys the secondary refrigerant to the freezing area for heat exchange, after the freezing area is frozen, the heated secondary refrigerant is returned to the carbon dioxide conveying mechanism and the heat exchange cooling mechanism for refrigeration again, liquid carbon dioxide serves as the secondary refrigerant to conduct circulating refrigeration in the freezing pipe, and the freezing period is effectively shortened.

Description

Technical Field

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

[0002] Ground freezing method refers to a special civil engineering construction method that uses artificial refrigeration technology to turn natural soil into artificial frozen soil, thereby improving the properties of the soil to facilitate the subsequent underground engineering construction. At present, the brine freezing method is usually used for ground freezing. The brine freezing method uses a compressor to reduce the temperature of the primary refrigerant and then the secondary refrigerant, and then injects low-temperature brine into the freezing pipe of the soil to continuously circulate to reduce the soil temperature, thereby gradually forming frozen soil. The freezing temperature of this method is around -30℃, the total freezing cycle is relatively long, and the frost heave and thaw sinking effect of the soil is obvious.

[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 and the existing cold brine freezing system have complicated processes and both require the use of compressors and other devices to reduce the primary refrigerant temperature, resulting in a longer freezing period for the stratum. At the same time, the freezing temperature is not low enough and the mechanical failure rate is high, resulting in an unstable freezing system.

[0005] Therefore, how to effectively improve the reliability of the ground freezing system, reduce the freezing temperature, shorten the freezing period, and enable the ground to freeze quickly 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 stable and reliable ground freezing system and method based on solid and liquid carbon dioxide, which can effectively reduce the freezing temperature and shorten the freezing period.

[0007] In order to achieve the above-mentioned purpose, the ground freezing system based on solid and liquid carbon dioxide 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

[0008] A heat exchange and cooling mechanism, wherein the heat exchange and cooling mechanism is configured to accommodate solid carbon dioxide therein and enable the solid carbon dioxide to sublime and absorb heat in the heat exchange and cooling mechanism to form a primary refrigerant,

[0009] a carbon dioxide delivery mechanism, wherein the carbon dioxide delivery mechanism is configured to deliver liquid carbon dioxide to the heat exchange and cooling mechanism, so that the liquid carbon dioxide exchanges heat with the primary refrigerant in the heat exchange and cooling mechanism to form a secondary refrigerant,

[0010] The circulation mechanism is configured to transport the secondary refrigerant formed in the heat exchange and cooling mechanism to the freezing pipe to exchange heat with the freezing area, and to transport the secondary refrigerant after heat exchange to the carbon dioxide transport mechanism so that the secondary refrigerant enters the heat exchange and cooling mechanism again for circulation.

[0011] A control mechanism, wherein the control mechanism is configured to control the working states of the heat exchange and cooling mechanism, the carbon dioxide delivery mechanism and the circulation mechanism.

[0012] Furthermore, the heat exchange and cooling mechanism comprises a heat exchange box, in which a spiral heat exchanger is arranged, and a refrigerant is distributed around the periphery of the spiral heat exchanger.

[0013] Furthermore, the heat exchange box is provided with an exhaust pipe and a feed port extending out of the top of the heat exchange box, respectively, and the feed port can accommodate the solid carbon dioxide.

[0014] Furthermore, the refrigerant is composed of a CaCl2 aqueous solution.

[0015] Furthermore, the carbon dioxide delivery mechanism includes a carbon dioxide storage tank and a first pipe body, the carbon dioxide storage tank contains liquid carbon dioxide, one end of the first pipe body is connected to the carbon dioxide storage tank, and the other end is connected to the bottom of the spiral heat exchanger.

[0016] Furthermore, a first pump body is provided on the first tube body.

[0017] Furthermore, the circulation mechanism includes a second tube body and a liquid return pipe, one end of the second tube body is connected to the top of the spiral heat exchanger, and the other end is connected to the freezing pipe, one end of the liquid return pipe is connected to the carbon dioxide storage tank, and the other end is connected to the freezing pipe.

[0018] Furthermore, the freezing pipe includes a first freezing pipe and a second freezing pipe, the first freezing pipe cooperates with the liquid return pipe, and the second freezing pipe cooperates with the second pipe body.

[0019] Furthermore, the second tube body and the liquid return tube are respectively provided with a second pump body and a third pump body.

[0020] In order to achieve the above-mentioned purpose, the present invention provides a ground freezing method based on solid and liquid carbon dioxide, based on the ground freezing system based on solid and liquid carbon dioxide, the freezing method comprises:

[0021] The control mechanism feeds solid carbon dioxide into the heat exchange and cooling mechanism, so that the solid carbon dioxide sublimates and absorbs heat through the heat exchange and cooling mechanism, forming a primary refrigerant in the heat exchange and cooling mechanism.

[0022] The control mechanism controls the carbon dioxide delivery mechanism to deliver liquid carbon dioxide to the heat exchange and cooling mechanism, so that the liquid carbon dioxide exchanges heat with the primary refrigerant and cools down, forming a secondary refrigerant in the heat exchange and cooling mechanism.

[0023] The control mechanism controls the circulation mechanism to transport the secondary refrigerant in the heat exchange and cooling mechanism to the cold junction pipe, so that the freezing area exchanges heat with the secondary refrigerant and freezes, and then transports the heated secondary refrigerant after heat exchange to the carbon dioxide transport mechanism.

[0024] The control mechanism continues to input solid carbon dioxide into the heat exchange and cooling mechanism, and the carbon dioxide conveying mechanism conveys the heated secondary refrigerant to the heat exchange and cooling mechanism for circulation.

[0025] The stratum freezing system and method based on solid and liquid carbon dioxide provided by the present invention adopts a heat exchange and cooling mechanism to sublime and absorb heat of solid carbon dioxide to form a primary refrigerant, and then liquid carbon dioxide is transported by a carbon dioxide transport mechanism, so that the liquid carbon dioxide exchanges heat with the primary refrigerant to form a secondary refrigerant. There is no need to use a compressor or other device to reduce the temperature of the primary refrigerant, and the solid carbon dioxide sublimation and heat absorption are directly used to cool the liquid carbon dioxide, thereby shortening the freezing period. At the same time, due to the characteristics of solid carbon dioxide, the temperature of the primary refrigerant is greatly reduced, thereby effectively reducing the freezing temperature of the secondary refrigerant.

[0026] Furthermore, the present invention also uses a circulation mechanism to transport the secondary refrigerant to the freezing zone for heat exchange, so that after the freezing zone is frozen, the heated secondary refrigerant is returned to the carbon dioxide transport mechanism and the heat exchange and cooling mechanism for refrigeration again, so that liquid carbon dioxide is circulated in the freezing pipe as the secondary refrigerant for refrigeration, further improving the refrigeration efficiency and effectively shortening the freezing cycle. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments.

[0028] Figure 1 The overall structural diagram of the ground freezing system based on solid and liquid carbon dioxide provided by the present invention;

[0029] Figure 2 It is a structural schematic diagram of the heat exchange and cooling mechanism in the present invention;

[0030] Figure 3 It is a structural schematic diagram of the carbon dioxide delivery mechanism in the present invention;

[0031] Figure 4 It is a schematic diagram of the structure of the freezing pipe in the present invention;

[0032] Figure 5 The present invention provides a flow chart of a ground freezing method based on solid and liquid carbon dioxide.

[0033] Reference numerals:

[0034] 100. Freezing area; 110. Freezing pipe; 111. First freezing pipe; 112. Second freezing pipe;

[0035] 200. heat exchange and cooling mechanism; 210. heat exchange box; 220. spiral heat exchanger; 230. exhaust pipe; 240. feed inlet; 250. mixed solution;

[0036] 300. Carbon dioxide delivery mechanism; 310. Carbon dioxide storage tank; 320. First tube body; 330. Liquid carbon dioxide; 340. First pump body;

[0037] 400. Circulation mechanism; 410. Second pipe body; 420. Liquid return pipe; 430. Second pump body; 440. Third pump body. DETAILED DESCRIPTION

[0038] 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.

[0039] See also Figure 1 , which shows an example of a ground freezing system based on solid and liquid carbon dioxide provided by the present invention.

[0040] As can be seen from the figure, the ground freezing system based on solid and liquid carbon dioxide in this example is used to cooperate with the freezing zone 100 of the formation. A freezing pipe 110 is provided in the freezing zone 100, which mainly includes a heat exchange and cooling mechanism 200, a carbon dioxide conveying mechanism 300, a circulation mechanism 400 and a control mechanism.

[0041] The heat exchange and cooling mechanism 200 is configured to accommodate solid carbon dioxide therein, and to allow the solid carbon dioxide to sublime and absorb heat in the heat exchange and cooling mechanism 200 to form a primary refrigerant. The carbon dioxide conveying mechanism 300 is configured to convey liquid carbon dioxide to the heat exchange and cooling mechanism 100, so that the liquid carbon dioxide exchanges heat and cools down with the primary refrigerant in the heat exchange and cooling mechanism 100 to form a secondary refrigerant. There is no need to use a compressor or other device to lower the temperature of the primary refrigerant, and the solid carbon dioxide sublimation and heat absorption are directly used to cool the liquid carbon dioxide, thereby shortening the freezing period. At the same time, due to the characteristics of solid carbon dioxide, the temperature of the primary refrigerant is greatly reduced, thereby effectively reducing the freezing temperature of the secondary refrigerant.

[0042] Furthermore, the circulation mechanism 400 is configured to transport the secondary refrigerant formed in the heat exchange and cooling mechanism 200 to the freezing pipe 110 for heat exchange with the freezing zone 100, and to transport the secondary refrigerant after heat exchange to the carbon dioxide transport mechanism 300, so that the secondary refrigerant enters the heat exchange and cooling mechanism 200 again for circulation, so that liquid carbon dioxide circulates in the freezing pipe 110 as a secondary refrigerant for refrigeration, further improving the refrigeration efficiency and effectively shortening the freezing cycle.

[0043] The control mechanism is configured to control the working states of the heat exchange and cooling mechanism 200, the carbon dioxide delivery mechanism 300 and the circulation mechanism 400, so that the solid carbon dioxide and the liquid carbon dioxide can be precisely matched, quickly cooled, improve the refrigeration efficiency, and effectively shorten the freezing period.

[0044] Combination Figure 2 The heat exchange and cooling mechanism 200 mainly includes a heat exchange box 210, in which a spiral heat exchanger 220 is provided. A refrigerant is distributed on the periphery of the spiral heat exchanger 220. The spiral heat exchanger 220 is evenly spirally distributed in the heat exchange box 210, so that the refrigerant can form high turbulence with solid carbon dioxide in the heat exchange box 210, thereby enhancing the heat exchange effect, so as to effectively improve the refrigeration efficiency in the heat exchange box 210.

[0045] In some embodiments, the refrigerant can be composed of organic solvents such as ethylene glycol, tetrachloroethylene, and chloroform. Granular solid carbon dioxide is added to the organic solvent in batches. The solid carbon dioxide can exchange heat with the organic solvent and mix to form solid carbon dioxide-organic solvent, and the solid carbon dioxide-organic solvent reaches a steady-state temperature.

[0046] Furthermore, since the heat capacity of water is generally greater than that of organic solvents, as a preferred setting scheme, the refrigerant is preferably composed of a CaCl2 aqueous solution, so that the CaCl2 aqueous solution can cooperate with solid carbon dioxide, and the solid carbon dioxide sublimates and absorbs heat, thereby effectively reducing the temperature of the CaCl2 aqueous solution and forming a mixed solution 250 with the CaCl2 aqueous solution, namely solid carbon dioxide-CaCl2 aqueous solution. Compared with solid carbon dioxide-organic solvent, the temperature of solid carbon dioxide-CaCl2 aqueous solution is easier to adjust, thereby forming a primary refrigerant with a stable lower temperature.

[0047] Since the temperature of the solid carbon dioxide-CaCl2 aqueous solution is approximately linearly related to the concentration of the CaCl2 aqueous solution, the temperature of the solid carbon dioxide-CaCl2 aqueous solution, i.e., the mixed solution 250, can be effectively controlled to be between -51°C and 0°C after the solid carbon dioxide sublimates and absorbs heat by controlling and adjusting the concentration of the CaCl2 aqueous solution, so that the temperature of the primary refrigerant is greatly reduced. Compared with the existing freezing system, the freezing temperature is reduced and the refrigeration efficiency is improved.

[0048] At the same time, since CaCl2 will fill the gaps between water molecules after dissolving in water, the arrangement of water molecules in the mixed solution 250 cannot freeze at sub-zero temperatures, thereby playing an antifreeze role. In addition, the eutectic temperature of the CaCl2 aqueous solution is very low, so that the mixed solution 250 can maintain a relatively low temperature to ensure that a relatively low temperature is always maintained during the heat exchange process between the primary refrigerant and liquid carbon dioxide, thereby reducing the temperature of the secondary refrigerant.

[0049] In order to ensure that solid carbon dioxide can stably form a primary refrigerant with the CaCl2 aqueous solution, the heat exchange box 210 is respectively provided with an exhaust pipe 230 and a feed port 240 extending from the top of the heat exchange box 210. The feed port 240 can accommodate solid carbon dioxide, so that the control mechanism can feed the solid carbon dioxide into the heat exchange box 210 in batches through the feed port 240, and control the feeding speed and amount of the solid carbon dioxide according to the degree of cooling and heat exchange between the solid carbon dioxide and the CaCl2 aqueous solution, thereby effectively controlling the stable coordination of the solid carbon dioxide and the CaCl2 aqueous solution.

[0050] Here, the control mechanism needs to ensure that the amount of solid carbon dioxide added can satisfy the requirement that solid carbon dioxide always exists in the mixed solution 250, so that the solid carbon dioxide is in a saturated state, to ensure that the solid carbon dioxide and the CaCl2 aqueous solution can exchange heat stably and ensure that the mixed solution 250 is at a lower temperature.

[0051] At the same time, solid carbon dioxide can be put into the heat exchange box 210 in the form of particles or rods to increase the contact area between the solid carbon dioxide and the CaCl2 aqueous solution, increase the cooling rate of the CaCl2 aqueous solution, and thus improve the freezing efficiency.

[0052] Furthermore, solid carbon dioxide sublimates and absorbs heat to lower the temperature of the CaCl2 aqueous solution, while generating gaseous carbon dioxide. The exhaust pipe 230 extends out of the top of the heat exchange box 210, so that the gaseous carbon dioxide can be discharged from the heat exchange box 210 through the exhaust pipe 230 to balance the pressure inside and outside the heat exchange box 210.

[0053] The heat exchange and cooling mechanism 200 thus formed cooperates with the heat exchange box 210, the spiral heat exchanger 220, the exhaust pipe 230 and the feed port 240, so that the solid carbon dioxide can stably exchange heat with the CaCl2 aqueous solution, forming a primary refrigerant with a lower temperature in the heat exchange box 210 to effectively reduce the freezing temperature. At the same time, the sublimation heat absorption of the solid carbon dioxide can effectively improve the refrigeration efficiency of the primary refrigerant.

[0054] Combination Figure 3In coordination therewith, the carbon dioxide delivery mechanism 300 can deliver liquid carbon dioxide to the heat exchange and cooling mechanism 200, so that the liquid carbon dioxide can exchange heat with the low-temperature primary refrigerant formed in the heat exchange and cooling mechanism 200 to form a secondary refrigerant with a lower temperature, thereby reducing the freezing temperature.

[0055] Specifically, the carbon dioxide delivery mechanism 300 includes a carbon dioxide storage tank 310 and a first tube body 320. The carbon dioxide storage tank 310 contains liquid carbon dioxide 330. One end of the first tube body 320 is connected to the heat exchange and cooling mechanism 200, and the other end is connected to the carbon dioxide storage tank 310, so that the liquid carbon dioxide 330 in the carbon dioxide storage tank 310 can be delivered to the heat exchange and cooling mechanism 200 through the first tube body 320.

[0056] Combination Figure 1 Furthermore, a first pump body 340 is provided on the first tube body 320, and the first pump body 340 is connected to the control mechanism, so that the control mechanism can control the first pump body 340 to work after the primary refrigerant is formed in the heat exchange and cooling mechanism 200, and suck the liquid carbon dioxide 330 in the carbon dioxide storage tank 310, and transport it to the heat exchange and cooling mechanism 200 through the first tube body 320, and can effectively control the transportation flow and speed of the liquid carbon dioxide 330 to ensure stable and rapid heat exchange between the liquid carbon dioxide 330 and the primary refrigerant.

[0057] Combination Figure 2 Preferably, one end of the first tube body 320 extends to the bottom of the carbon dioxide storage tank 310, and the other end is connected to the bottom of the spiral heat exchanger 220 in the heat exchange and cooling mechanism 200, so as to ensure that the first pump body 340 can effectively extract the liquid carbon dioxide 330, and at the same time enable the liquid carbon dioxide 330 to be transported to the heat exchange box 210 in a stable state through the first tube body 320, thereby reducing problems such as pipeline vibration and unstable operation of the liquid carbon dioxide 330 during transportation.

[0058] The carbon dioxide delivery mechanism 300 thus constructed can cooperate with the carbon dioxide storage tank 310, the first tube body 320 and the first pump body 340 to stably deliver the liquid carbon dioxide 330 to the heat exchange and cooling mechanism 200, so that the liquid carbon dioxide exchanges heat with the primary refrigerant to quickly reduce the temperature of the liquid carbon dioxide 330.

[0059] At the same time, directly using the primary refrigerant formed by the sublimation and absorption of heat of solid carbon dioxide to cool the liquid carbon dioxide can effectively shorten the freezing period. Since the primary refrigerant can always maintain a low temperature during the heat exchange process with the liquid carbon dioxide 330, the temperature of the liquid carbon dioxide 330 is greatly reduced, and a secondary refrigerant with a lower temperature is formed in the heat exchange and cooling mechanism 200, thereby reducing the cooling temperature.

[0060] Here, since the liquid carbon dioxide 330 needs to be heat exchanged with the primary refrigerant to form a secondary refrigerant and then transported to the freezing zone 100 to cool and freeze the freezing zone 100, the flow rate of the liquid carbon dioxide 330 transported to the heat exchange and cooling mechanism 200 is adapted to the size of the freezing zone 100. In a specific application process, the flow rate of the liquid carbon dioxide 330 is preset according to the size of the freezing zone 100, and the primary refrigerant flow rate that matches the transport flow rate of the liquid carbon dioxide 330 is obtained through a theoretical calculation formula, so that the secondary refrigerant formed by the liquid carbon dioxide 330 exchanging heat with the primary refrigerant in the heat exchange and cooling mechanism 200 can meet the cooling and freezing of the freezing zone 100.

[0061] Combination Figure 1 In order to further shorten the freezing cycle, the circulation mechanism 400 is configured to transport the secondary refrigerant formed in the heat exchange and cooling mechanism 200 to the freezing pipe 110, exchange heat with the freezing area 100, and return the secondary refrigerant heated by heat exchange to the carbon dioxide transport mechanism 300 for circulation, so as to improve the freezing efficiency and shorten the freezing cycle.

[0062] Specifically, the circulation mechanism 400 mainly includes a second tube body 410 and a liquid return pipe 420. One end of the second tube body 410 is connected to the heat exchange and cooling mechanism 200, and the other end is connected to the freezing pipe 110 in the freezing zone 100, so that the secondary refrigerant formed in the heat exchange and cooling mechanism 200 can be transported to the second tube body 410 through the second tube body 410, and exchange heat with the stratum in the freezing zone 100, so that the stratum in the freezing zone is frozen.

[0063] Furthermore, one end of the return liquid pipe 420 is connected to the carbon dioxide delivery mechanism 300, and the other end is connected to the freezing pipe 110 in the freezing zone 100, so that the secondary refrigerant after heat exchange and heating in the freezing zone 100 can be transported back to the carbon dioxide delivery mechanism 300 through the return liquid pipe 420, and then transported from the carbon dioxide delivery mechanism 300 to the heat exchange and cooling mechanism 200 for further cooling, thereby realizing the circulation of the secondary refrigerant.

[0064] Combination Figure 4 In coordination with this, the freezing pipe 110 in the freezing zone 100 includes a first freezing pipe 111 and a second freezing pipe 112 distributed in parallel, so that one end of the second tube body 410 is connected to the top of the spiral heat exchanger 220 in the heat exchange and cooling mechanism 200, and the other end is connected to the second freezing pipe 112. At the same time, one end of the return liquid pipe 420 is connected to the top of the carbon dioxide delivery mechanism 300, and the other end is connected to the first freezing pipe 111, so that the first freezing pipe 111 and the second freezing pipe 112 are respectively coordinated with the return liquid pipe 420 and the second tube body 410 to realize the circulation of the secondary refrigerant in the freezing zone 100.

[0065] Combination Figure 1 and Figure 4As an example, the secondary refrigerant enters the second freezing pipe 112 through the second pipe body 410, and flows into the freezing zone 100, exchanges heat with the formation, causing the formation to cool down and freeze. During this process, the secondary refrigerant heats up to form a gas-liquid mixture, and enters the first freezing pipe 111, returns to the carbon dioxide delivery mechanism 300 through the first freezing pipe 111, and can enter the heat exchange and cooling mechanism 200 again through the first pipe body 310 for cooling, and then acts as a secondary refrigerant to cool down and freeze the freezing zone 100, circulating in this freezing system.

[0066] Furthermore, a second pump body 430 and a third pump body 440 are respectively provided on the second tube body 410 and the return liquid pipe 420. The second pump body 430 and the third pump body 440 are respectively connected to the control mechanism, so that the control mechanism can control the flow rate and speed of the secondary refrigerant delivered to the freezing tube 110 through the second pump body 430 to improve the freezing efficiency of the freezing area 100, and can also control the flow rate and speed of the secondary refrigerant after heat exchange and heating returned to the carbon dioxide delivery mechanism 300 through the third pump body 440, so that the secondary refrigerant after heat exchange and heating can be adapted to the generation speed of the primary refrigerant, thereby improving the close fit between the secondary refrigerant and the primary refrigerant, and ensuring that the secondary refrigerant can be quickly cooled and circulated again, thereby improving the freezing efficiency and shortening the freezing cycle.

[0067] The circulation mechanism 400 thus constructed cooperates with the freezing pipe 110 through the second pipe body 410, the return liquid pipe 420 and the freezing pipe 110 to achieve rapid cooling and freezing of the freezing area 100 by the secondary refrigerant and realize the circulation of the secondary refrigerant to improve the freezing efficiency and shorten the freezing cycle.

[0068] Preferably, in order to realize the continuous flow circulation of the secondary refrigerant, the carbon dioxide delivery mechanism 300 also serves as a storage mechanism for the secondary refrigerant. The secondary refrigerant is pre-stored in the carbon dioxide delivery mechanism 300, so that before the secondary refrigerant in the freezing tube 110 is heated up and returned to the carbon dioxide delivery mechanism 300, the secondary refrigerant pre-stored in the carbon dioxide delivery mechanism 300 can first circulate into the heat exchange and cooling mechanism 200, and then the secondary refrigerant in the freezing tube 110 is heated up and returned to the carbon dioxide delivery mechanism 300, and also enters the heat exchange and cooling mechanism 200, thereby realizing the continuous flow circulation of the secondary refrigerant to effectively shorten the freezing cycle.

[0069] In order to effectively control the coordination of solid carbon dioxide and liquid carbon dioxide, the freezing system also includes a control mechanism. For example, the control mechanism can be composed of an existing control cabinet or a remote controller, so that the control mechanism can control the working states of the thermal cooling mechanism 200, the carbon dioxide delivery mechanism 300 and the circulation mechanism 400.

[0070] As an example, the control mechanism can be connected to the heat exchange and cooling mechanism 200 to control the introduction of solid carbon dioxide so that the solid carbon dioxide and the CaCl2 aqueous solution can be stably combined to form a primary refrigerant.

[0071] Furthermore, the control mechanism can also be connected to the first pump body 340 in the carbon dioxide delivery mechanism 300 to accurately control the delivery of liquid carbon dioxide so that the delivery amount of liquid carbon dioxide is compatible with the formation of the primary refrigerant, so that the liquid carbon dioxide can stably exchange heat with the primary refrigerant to form a secondary refrigerant.

[0072] Correspondingly, the control mechanism can also connect the second pump body 430 and the third pump body 440 in the circulation mechanism 400, accurately control the coordination between the secondary refrigerant and the freezing zone, and the effective circulation of the secondary refrigerant after heat exchange and heating, thereby improving the close coordination between the heat exchange and cooling mechanism 200, the carbon dioxide delivery mechanism 300 and the circulation mechanism 400, improving the freezing efficiency and shortening the freezing cycle.

[0073] Thus, the ground freezing system based on solid and liquid carbon dioxide provided by the present invention is formed.

[0074] The present invention also provides a ground freezing method based on solid and liquid carbon dioxide, and a ground freezing system based on solid and liquid carbon dioxide provided by the above scheme. The freezing method includes:

[0075] Combination Figure 1 and Figure 5 First, the control mechanism inputs solid carbon dioxide into the heat exchange and cooling mechanism 200, so that the solid carbon dioxide sublimates and absorbs heat through the heat exchange and cooling mechanism 200, forming a primary refrigerant in the heat exchange and cooling mechanism 200.

[0076] The control mechanism feeds the solid carbon dioxide into the heat exchange box 210 in batches through the feed port 240, and controls the feeding speed and amount of the solid carbon dioxide according to the degree of cooling and heat exchange between the solid carbon dioxide and the CaCl2 aqueous solution, so that the solid carbon dioxide sublimates and absorbs heat in the heat exchange box 210, effectively reducing the temperature of the CaCl2 aqueous solution, and forming a mixed solution 250 with the CaCl2 aqueous solution with a temperature between -51°C and 0°C, i.e., solid carbon dioxide-CaCl2 aqueous solution, thereby forming a primary refrigerant. Compared with the existing freezing system, the freezing temperature is greatly reduced and the refrigeration efficiency is improved.

[0077] In this process, the solid carbon dioxide sublimates and absorbs heat to generate gaseous carbon dioxide, which is discharged out of the heat exchange box 210 through the exhaust pipe 230 to balance the pressure inside and outside the heat exchange box 210.

[0078] Next, the control mechanism controls the carbon dioxide delivery mechanism 300 to deliver liquid carbon dioxide to the heat exchange and cooling mechanism 200 , so that the liquid carbon dioxide exchanges heat with the primary refrigerant for cooling, and forms a secondary refrigerant in the heat exchange and cooling mechanism 200 .

[0079] The control mechanism controls the operation of the first pump body 340 to pump the liquid carbon dioxide 330 in the carbon dioxide storage tank 310, so that the liquid carbon dioxide 330 is transported to the heat exchange box 210 through the first tube body 320, exchanges heat with the primary refrigerant, and quickly reduces the temperature of the liquid carbon dioxide 330 to form a secondary refrigerant.

[0080] Therefore, directly using the primary refrigerant formed by the sublimation and absorption of heat of solid carbon dioxide to cool the liquid carbon dioxide can effectively shorten the freezing period. Since the primary refrigerant can always maintain a low temperature during the heat exchange process with the liquid carbon dioxide 330, the temperature of the liquid carbon dioxide 330 is greatly reduced, and a secondary refrigerant with a lower temperature is formed in the heat exchange and cooling mechanism 200, thereby reducing the cooling temperature.

[0081] Next, the control mechanism controls the circulation machine 400 to transport the secondary refrigerant in the heat exchange and cooling mechanism 200 to the cold junction pipe 110, so that the freezing area 100 exchanges heat with the secondary refrigerant and freezes, and then transports the heat-exchanged and heated secondary refrigerant to the carbon dioxide transport mechanism 300.

[0082] The secondary refrigerant enters the second freezing pipe 112 of the cold junction pipe 110 through the second pipe body 410, and flows into the freezing zone 100, exchanging heat with the formation, causing the formation to cool down and freeze. During this process, the secondary refrigerant heats up to form a gas-liquid mixture, and enters the first freezing pipe 111, and returns to the carbon dioxide delivery mechanism 300 through the first freezing pipe 111.

[0083] Next, the control mechanism continues to inject solid carbon dioxide into the heat exchange and cooling mechanism 200, so that the carbon dioxide delivery mechanism 300 delivers the heated secondary refrigerant to the heat exchange and cooling mechanism 200 for circulation.

[0084] The heated secondary refrigerant enters the heat exchange and cooling mechanism 200 again through the first tube 310, exchanges heat and cools down with the primary refrigerant, and again acts as the secondary refrigerant through the circulation mechanism 400 to cool and freeze the freezing area 100, circulating in the freezing system.

[0085] The stratum freezing system and method based on solid and liquid carbon dioxide provided by the present invention cooperates with each other through the heat exchange cooling mechanism 200, the carbon dioxide conveying mechanism 300, the circulation mechanism 400 and the control mechanism. There is no need to use a compressor or other device to reduce the temperature of the primary refrigerant. The solid carbon dioxide sublimation heat absorption is directly used to cool the liquid carbon dioxide, thereby shortening the freezing period. Due to the characteristics of solid carbon dioxide, the temperature of the primary refrigerant is greatly reduced, thereby effectively reducing the freezing temperature of the secondary refrigerant, and the secondary refrigerant is circulated to improve the freezing efficiency of the freezing zone and shorten the freezing period.

[0086] 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 ground freezing system based on solid and liquid carbon dioxide, used to cooperate with a freezing zone of the ground, wherein a freezing pipe is provided in the freezing zone, characterized in that: include A heat exchange and cooling mechanism, wherein the heat exchange and cooling mechanism is configured to accommodate solid carbon dioxide therein and enable the solid carbon dioxide to sublime and absorb heat in the heat exchange and cooling mechanism to form a primary refrigerant, a carbon dioxide delivery mechanism, wherein the carbon dioxide delivery mechanism is configured to deliver liquid carbon dioxide to the heat exchange and cooling mechanism, so that the liquid carbon dioxide exchanges heat with the primary refrigerant in the heat exchange and cooling mechanism to form a secondary refrigerant, The circulation mechanism is configured to transport the secondary refrigerant formed in the heat exchange and cooling mechanism to the freezing pipe to exchange heat with the freezing area, and to transport the secondary refrigerant after heat exchange to the carbon dioxide transport mechanism so that the secondary refrigerant enters the heat exchange and cooling mechanism again for circulation. A control mechanism, wherein the control mechanism is configured to control the working states of the heat exchange and cooling mechanism, the carbon dioxide delivery mechanism and the circulation mechanism.

2. The ground freezing system based on solid and liquid carbon dioxide according to claim 1, characterized in that: The heat exchange and cooling mechanism comprises a heat exchange box, in which a spiral heat exchanger is arranged, and a refrigerant agent is distributed around the spiral heat exchanger.

3. The ground freezing system based on solid and liquid carbon dioxide according to claim 2, characterized in that: The heat exchange box is provided with an exhaust pipe and a feed port extending from the top of the heat exchange box, respectively, and the feed port can accommodate the solid carbon dioxide.

4. The ground freezing system based on solid and liquid carbon dioxide according to claim 2, characterized in that: The refrigerant is composed of a CaCl2 aqueous solution.

5. The ground freezing system based on solid and liquid carbon dioxide according to claim 2, characterized in that: The carbon dioxide delivery mechanism comprises a carbon dioxide storage tank and a first pipe body, wherein the carbon dioxide storage tank contains liquid carbon dioxide, and one end of the first pipe body is connected to the carbon dioxide storage tank, and the other end is connected to the bottom of the spiral heat exchanger.

6. The ground freezing system based on solid and liquid carbon dioxide according to claim 5, characterized in that: The first tube body is provided with a first pump body.

7. The ground freezing system based on solid and liquid carbon dioxide according to claim 2, characterized in that: The circulation mechanism includes a second tube body and a liquid return pipe, wherein one end of the second tube body is connected to the top of the spiral heat exchanger and the other end is connected to the freezing pipe, and one end of the liquid return pipe is connected to the carbon dioxide storage tank and the other end is connected to the freezing pipe.

8. The ground freezing system based on solid and liquid carbon dioxide according to claim 7, characterized in that: The freezing pipe comprises a first freezing pipe and a second freezing pipe, wherein the first freezing pipe cooperates with the liquid return pipe, and the second freezing pipe cooperates with the second pipe body.

9. The ground freezing system based on solid and liquid carbon dioxide according to claim 7, characterized in that: The second pipe body and the liquid return pipe are respectively provided with a second pump body and a third pump body.

10. A ground freezing method based on solid and liquid carbon dioxide, characterized in that: Based on the ground freezing system based on solid and liquid carbon dioxide according to any one of claims 1 to 9, the freezing method comprises: The control mechanism feeds solid carbon dioxide into the heat exchange and cooling mechanism, so that the solid carbon dioxide sublimates and absorbs heat through the heat exchange and cooling mechanism, forming a primary refrigerant in the heat exchange and cooling mechanism. The control mechanism controls the carbon dioxide delivery mechanism to deliver liquid carbon dioxide to the heat exchange and cooling mechanism, so that the liquid carbon dioxide exchanges heat with the primary refrigerant and cools down, forming a secondary refrigerant in the heat exchange and cooling mechanism. The control mechanism controls the circulation mechanism to transport the secondary refrigerant in the heat exchange and cooling mechanism to the cold junction pipe, so that the freezing area exchanges heat with the secondary refrigerant and freezes, and then transports the heated secondary refrigerant after heat exchange to the carbon dioxide transport mechanism. The control mechanism continues to input solid carbon dioxide into the heat exchange and cooling mechanism, and the carbon dioxide conveying mechanism conveys the heated secondary refrigerant to the heat exchange and cooling mechanism for circulation.

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