RU2768247C1 - Three-circuit system of all-season thermal stabilization of permafrost soils of bases - Google Patents

Abstract

FIELD: construction.

SUBSTANCE: invention relates to construction of buildings and structures on permafrost soils, in particular, is intended for freezing and all-season thermal stabilization of soils of bases of buildings and structures. Three-circuit system of all-season thermal stabilization of permafrost soils of bases consists of three indirectly interconnected jointly operating soil cooling circuits. First circuit is represented by a refrigerating machine intended for cooling of a coolant. Second circuit is represented by a hydraulic module providing circulation of the coolant. Third circuit is represented by a heat stabilizer equipped with a heat exchanger. All three cooling circuits are connected by means of pipelines and are equipped with control automation elements made in the form of controllers and sensors.

EFFECT: providing high performance and efficiency due to providing significant heat transfer characteristics of the system, possibility of placing electrical equipment used by the system at a distance from explosive and fire hazardous areas, possibility of system operation control process automation, possibility of considerable soil massifs freezing till required design temperatures are achieved, possibility of mobile use of the system for emergency freezing of soils on hazardous areas of critical thawing.

1 cl, 3 dwg

Description

The invention relates to the field of construction of buildings and structures on permafrost soils, in particular, is intended for freezing and all-season thermal stabilization of the soils of the foundations of buildings and structures.

Known systems and methods for collecting and processing permafrost gases, as well as cooling permafrost soils (hereinafter referred to as MMG), in which gas is obtained from the sacrificial area of thawing permafrost. Dissociation of gas in a non-combustible chemical process and circulation of the gas component is carried out through the retained area of the defrosting area of the MMG to cool the retained area (Patent No. US 8888408 B2. publ. 2014-11-18).

However, the disadvantage of the described technical solution is the impossibility of ensuring explosion and fire safety by placing the used electrical equipment outside hazardous production facilities and areas, as well as the lack of automation of the system operation control process. In addition, the described solution, unlike the present invention, cannot be used for emergency freezing of soils in dangerous areas of critical thawing.

A known system for thermal stabilization of the soil bases on permafrost soils, including a circuit of cooling pipes with a plugged end on one side and an open end on the other, the cavity of which is filled with a non-freezing liquid. This system also includes layers of thermal insulation placed above the pipe contour and backfilling. The cooling pipes are located under the soil filling and thermal insulation layer with a slope to the longitudinal axis of the base towards the closed ends. The open ends of the pipes are brought out of the boundaries of the contour, within which the cooling pipes are equipped with cooling elements installed in their internal cavities. Along the perimeter of the circuit, vertical sleeves are additionally installed, the cavity of which is filled with a non-freezing liquid. Cooling elements are installed inside the sleeves, and the upper part of each sleeve and the cooling pipe is provided with a lid with a hole for accommodating the cooling element and a filler neck with a plug (Patent No. RU 116871. Published on June 10, 2012).

However, despite the fact that the known system described above makes it possible to provide thermal stabilization of foundation soils, the disadvantage of such a system is a decrease in economic efficiency, which occurs due to the lack of an option for thermal stabilization in the mode of seasonally operating cooling devices (hereinafter referred to as SDA) due to sufficiently low temperatures. ambient air during cold seasons. Thermal stabilization is carried out here exclusively in the energy-consuming mode of forced cooling. There is also no possibility of automating the process of managing the functioning of the system. In addition, the described system is intended exclusively for permanent stationary operation and cannot, if necessary, be used mobilely for emergency temporary freezing of soils in dangerous areas of critical thawing. Additionally, in the described technical solution, there is no possibility of ensuring explosion and fire safety by placing the used electrical equipment outside hazardous production facilities and zones.

Known system of temperature stabilization of soil foundations of buildings and structures, including seasonally operating cooling devices. Each of these devices contains an evaporation zone, along the edges of which there is a transport zone and a condensation zone, and is made in the form of a tubular section body with the possibility of filling with a coolant. In this case, the condensation zones are installed above the soil surface at an angle of 90° to the horizon and are equipped with heat exchangers, and the evaporation zones are placed in the base of the structure parallel to each other with a slope of 10° to 0° to the longitudinal axis of the structure. Evaporation zones are placed in through holes drilled over the entire area of the structure, brought out of the contour of the structure from two opposite sides into trenches oriented along the longitudinal axis of the structure, and connected to transport zones laid in trenches. The free edges of the transport zones are connected to the condensation zones, collected in a bush on each of the mentioned sides, fixed on a supporting structure, equipped with a platform for refueling and maintenance of cooling devices. Additionally, a heat shield was laid on the ground surface of the foundation, under the entire structure, directly under the floors of the first floor (Patent No. RU 141110. Published on May 27, 2014).

However, in the described well-known system, there is no possibility of ensuring explosion and fire safety at the facility by placing the electrical equipment used by the system at a distance from hazardous production facilities and zones, as well as the possibility of automating the process of controlling the system operation. Also, the described stationary system cannot, if necessary, be used mobilely for emergency freezing of soils in dangerous areas of critical thawing.

A known method of thermal stabilization of soils of the foundations of pile supports of pipelines and pipelines of underground laying, in which icy soils are excavated with the laying of a composite material replacing the excavation. At the edges of the excavation, at least two soil thermal stabilizers are installed. At the same time, the composite material has a composition at a certain ratio of components, and for the impregnation of the polymer, a heat-transfer fluid with a high heat capacity and a low freezing point is chosen (Patent No. RU 2616029. Published on April 14, 2017).

However, despite the fact that the described well-known technical solution is intended to improve the reliability of foundations and safe operation of main pipelines in the areas of distribution of MMG, it is economically inefficient due to the significant amount of excavation and laying of composite materials replacing excavations while duplicating with thermal stabilizers. In addition, this technical solution allows the violation of the soil and vegetation layer, which leads to the activation of erosion processes and the violation of the natural temperature regime of the foundation soils. The present invention does not provide for earthworks, and also, due to automation of control, it is preferable for use on such remote linear objects as pipelines and railways.

Known railroad embankment on permafrost, which uses a cooling system placed in the body of railroad embankments on the MMG. The cooling system at the base of the embankment consists of two independent parts - main and auxiliary. The main part is volumetric rigid, made of waste tanks, installed on a frozen base along the axis of the embankment and connected by pipelines. The auxiliary part is made in the form of a flat resilient-elastic carpet, inside of which Peltier thermoelectric modules are fixed, and laid in the upper layer of the embankment at the base of the ballast prism (Patent No. RU 2657310. Published on June 13, 2018).

However, the described well-known technical solution has an extremely low efficiency (hereinafter referred to as efficiency) and causes difficulties when using this technology in areas of increased explosion and fire hazard (for example, in oil and gas industry enterprises). In the described well-known system, there is no possibility of ensuring explosion and fire safety at the facility by placing the electrical equipment used by the system at a distance from hazardous production facilities and areas, as well as the possibility of automating the process of controlling the system operation. Also, the described stationary system cannot, if necessary, be used mobilely for emergency freezing of soils in dangerous areas of critical thawing. Another disadvantage of such a system is the decrease in economic efficiency, which occurs due to the lack of an option for thermal stabilization in the COA mode due to sufficiently low ambient temperatures in cold seasons. Thermal stabilization is carried out here exclusively in the energy-consuming mode of forced cooling. In addition, there is no possibility of automating the process of managing the functioning of the system.

With thermal stabilization, cooling occurs when heat is absorbed from the soil surrounding the evaporative part of the thermal stabilizer. To maintain continuous cyclic operation of the heat stabilizer, heat is also removed from the condenser part of the heat stabilizer. In currently existing thermal stabilization systems, this function is provided by the ground part of the thermal stabilizer through contact with atmospheric air of a sufficiently low temperature. When the temperature difference between the soil and the air surrounding the condenser part is about 12° Celsius, heat removal from the ground part of the heat stabilizer can occur in the SDA mode (natural refrigerant circulation mode that does not require artificial energy sources). Also, at present, there are double-circuit systems for thermal stabilization of foundation soils, in which the cooling of the “condenser” part occurs due to the operation of a specialized refrigeration unit located in direct contact with the thermal stabilizer.

The studied level of technology did not allow to identify the closest analogue to the claimed technical solution with obtaining a similar technical result.

The objective of the present invention is the possibility of all-weather freezing and maintaining the temperatures of the foundation soils within the required design values.

The technical result of the invention is as follows:

- extremely high efficiency rates due to the provision of significant heat transfer characteristics of the system (thermal conductivity coefficient of the condenser part of the thermal stabilizer in the system, heat flow from the ground to the condenser part, linear thermal resistance of the thermal stabilizer in the system);

- the possibility of placing the electrical equipment used by the system at a distance from explosive and fire hazardous areas;

- the possibility of automating the process of controlling the functioning of the system during the transition from the SDA mode to the mode of forced cooling of soils and vice versa in accordance with the current natural and climatic conditions and thermometry data of the foundation soils;

- the ability to freeze large areas of soil in the shortest possible time until the required design temperatures are reached with further operation in an economical mode to maintain the required temperature regime;

- the possibility of mobile use of the system for emergency freezing of soils in dangerous areas of critical thawing, determined by the results of geotechnical monitoring.

The stated technical result is achieved by the fact that the three-loop system for all-season thermal stabilization of permafrost soils of bases consists of three indirectly interconnected jointly working soil cooling circuits, while the first circuit is represented by a refrigeration machine designed to cool the coolant, the second circuit is represented by a hydraulic module that circulates the coolant, the third circuit represented by a heat stabilizer equipped with a heat exchanger, all three cooling circuits are connected by pipelines and equipped with control automation elements.

In an embodiment, in order to increase the efficiency, in a three-circuit system, the refrigeration machine can be made in the form of a closed unit in which a compressor, a condenser, a thermostatic expansion valve and an evaporator are connected in series, while the hydraulic module includes pumps for pumping the coolant, connected indirectly and, accordingly, with the evaporator of the refrigerating machine and the heat exchanger of the heat stabilizer, in addition, the first and second circuits are equipped with control automation elements made in the form of controllers and sensors.

The present invention is described by detailed explanation and diagrams, in which:

Fig. 1 shows a block diagram of a three-circuit system for all-season thermal stabilization of MMG bases;

Fig. 2 characterizes the technical elements of the blocks of each of the three circuits of the system;

Fig. 3 explains the block diagram of the automation elements of a three-loop system.

Terms:

Efficiency - efficiency factor;

MMG - permafrost soil;

SOU - seasonally operating cooling device;

TSVT is a three-loop system for all-season thermal stabilization of permafrost base soils.

The three-circuit system of all-season thermal stabilization of permafrost soils of the bases contains indirectly connected three jointly working circuits 1, 2, 3 of soil cooling (Figure 1). The first circuit 1 is made in the form of a refrigerating machine intended for cooling the coolant. The second intermediate circuit 2 is made in the form of a hydraulic module. The third circuit 3 is made of a heat stabilizer equipped with a heat exchanger, installed in the base soil. Each circuit is connected by pipelines and equipped with control automation elements, including the main controller 4.

To increase the efficiency, the chiller of the primary circuit 1 has a closed circuit (Fig. 2). A closed circuit is formed from interconnected by a direct connection, compressor 5, condenser 6, thermostatic valve 7, evaporator 8.

The first circuit 1 is connected to the second intermediate circuit 2 via an evaporator 8, which is connected to the pumps 9 and 10 of the hydronic module.

Pumps 9, 10 are indirectly connected to the third circuit 3, made of a thermal stabilizer 11. A heat exchanger 12 is installed on the thermal stabilizer 11. The thermal stabilizer 11 is installed with its lower end in the permafrost soil 13. In this case, the heat exchanger 12 is located above the permafrost soil 13 of the base.

The main controller 4 is interconnected with the controllers and sensors of each of the circuits 1, 2, 3.

The chiller of the primary circuit 1 is equipped with an automation element in the form of a controller 14 connected to refrigerant temperature sensors 15 and refrigerant pressure sensors 16 (Fig. 3).

The hydraulic module of the secondary circuit 2 is equipped with an automation element in the form of a controller 17 connected to the coolant flow sensors 18, the coolant level sensors 19, the coolant temperature sensor 20, and the coolant pressure sensors 21.

The elements of the third circuit 3, namely the heat stabilizer 11 and the heat exchanger 12, installed in the permafrost soil 13 of the base, are equipped with automation elements in the form of a coolant supply controller 22 connected to the coolant temperature sensors 23. In addition, the thermocouple controller 24 is connected to the soil temperature sensors 25.

The principle of operation of TSVT is as follows.

TSVT consists of three jointly working cooling circuits 1, 2, 3, the result of which is the cooling of the foundation soils to the required design values (Fig. 1, 2, 3).

The first 1 circuit of the TSVT is a refrigerating machine designed to cool the liquid. Ammonia, freon (freon), and SF6 gas were used as the refrigerant of the refrigeration machine of circuit 1. The heat stabilizer 11 was installed at one of its ends in permafrost soil 13 of the base (hereinafter referred to as soil). At the same time, the heat exchanger 12 is located above the ground 13. The coolant - antifreeze, inorganic compounds (brine), organic compounds (glycol solutions), from the hydraulic module with the help of a pump 10 entered the heat exchanger 12 cooled for further heat exchange with the refrigerant of the thermal stabilizer 11, which directly cools the soil 13 of the base . Then it went to the evaporator 7, which is in contact with the refrigerant of the refrigerating machine of circuit 1. After the refrigerant reached the required temperature, it moved in the reverse order with the help of pump 9 to the heat exchanger 12 of the thermal stabilizer 11. The temperature regime for year-round maintenance of the required temperature of the MMG was carried out by the controller 14, refrigerant temperature sensors 15; and refrigerant pressure sensors 16.

The present invention can be used both stationary (permanent operation) and mobile, allowing you to quickly set the temperature values required by the project in the bases of buildings and structures, as well as to carry out effective emergency freezing of the soils of the bases of buildings and structures until the design temperatures are reached at those identified through geotechnical monitoring. areas of critical thaw.

The proposed invention allows for year-round thermal stabilization (without summer and spring-autumn pauses in the operation of the LCS) of the soils of the foundations of buildings and structures within the required design temperature values during the entire life of the construction object.

The presented TSVT system can be mounted, including on previously installed and previously operated at the facility heat stabilizers from any manufacturer and with any configuration (geometric parameters, type of refrigerant, etc.).

In addition, the proposed technical solution makes it possible to place all the electrical equipment used by the system (refrigerator, hydraulic module, automation elements, etc.) at considerable distances from hazardous production facilities and areas in order to ensure explosion and fire safety.

The proposed technical solution makes it possible to carry out the process of year-round cooling and thermal stabilization of the soils of the foundations of buildings and structures in automatic mode. The alternation of free cooling with the use of seasonally operating thermostats and forced cooling occurs through automated control of sensors and controllers. The use of this principle of operation makes it possible to achieve a significant increase in the efficiency and safety of operation, as well as to reduce the number of operating personnel.

Claims (2)

1. A three-circuit system for all-season thermal stabilization of permafrost soils of bases, characterized by the fact that it consists of three indirectly interconnected jointly operating soil cooling circuits, while the first circuit is represented by a refrigeration machine designed to cool the coolant, the second circuit is represented by a hydraulic module that circulates the coolant, the third circuit is represented by with a heat stabilizer equipped with a heat exchanger, all three cooling circuits are connected by pipelines and equipped with control automation elements. 2. A three-circuit system according to claim 1, characterized in that the refrigeration machine is made in the form of a closed unit in which a compressor, a condenser, a thermostatic expansion valve and an evaporator are connected in series, while the hydraulic module includes pumps for pumping the coolant connected indirectly and, accordingly, with the evaporator of the refrigeration machine and a heat exchanger of a heat stabilizer, in addition, the first and second circuits are equipped with control automation elements made in the form of controllers and sensors.

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