RU2620664C1 - Method for heat stabilization of permafrost soils and device for its implementation - Google Patents

Abstract

FIELD: construction.

SUBSTANCE: device for heat stabilization of permafrost soils contains at least two soil heat stabilizers, based on biphase thermosyphones, comprising the aboveground condenser part and the underground transport and evaporation parts, and at least one heat-conducting element made in the form of a plate of heat-dissipative material with the thermal conductivity of at least 5 W/m⋅K. At least two soil heat stabilizers are installed on both sides of the underground-laid pipeline and at least one heat conductive element is installed under the heat insulation material separating the underground-laid pipe from the roof of permafrost soils and has openings for connecting to the evaporating parts of at least two soil heat stabilizers.

EFFECT: increasing the efficiency of preserving permafrost soils or freezing weak soils of the bases of pipeline system objects to ensure the safety during the designated service life at design modes.

8 cl, 2 dwg, 1 tbl, 1 ex

Description

The group of inventions relates to the field of construction of pipelines of underground laying and can be used to provide thermal stabilization of soils during underground laying of pipelines on permafrost and soft soils.

A device for temperature thermal stabilization of permafrost soils [patent for invention RU 2556591 C1, publ. 07/10/2015, IPC: E02D 3/115], containing a thermostabilizer based on a two-phase thermosiphon, including an aboveground condenser part and underground transport and evaporation parts placed in a sleeve with a refrigerant. The sleeve is a hollow cylindrical body with a bottom and a sealing element at the upper end with an opening for installing a heat stabilizer. The sealing element is a detachable stuffing box seal, which consists of a support ring mounted on a circular step made in the sleeve, a pressure ring and heat-expanded graphite packing rings sandwiched between them.

It is also known cooled base structures [patent for utility model RU 143963 U1, publ. 08/10/2014, IPC: E02D 3/115], including soil filling and a seasonal cooling system, made in the form of a gravitational heat-tight sealed pipe filled with low boiling liquid, consisting of a condenser and an evaporator, and a container made of elastic material coaxially installed from the outside of the pipe with cold storage substance enclosed in a rigid frame. The upper part of the condenser is located above the surface of the soil dump and is equipped with a horizontal circular finning on the outside, and the upper part of the evaporator is located in the soil dump. The length of the bottom of the condenser corresponds to the distance between the surface of the soil dump and the bottom of the seasonal thawing layer. The container with the cold storage substance is made with a length corresponding to the length of the lower part of the capacitor, and is located at the level of the lower part of the capacitor. The fins inside the tank are made with holes for the passage of the cold storage substance. The lower part of the evaporator is located at the base of the soil dump.

The disadvantages of the known analogues is the use in devices of thermal stabilization of permafrost soils of liquid refrigerants, characterized by a high evaporation rate in violation of the tightness of cooling systems. In addition, such devices for thermal stabilization of permafrost soils are not resistant to corrosion and require significant costs for their operation.

The closest analogue of the claimed group of inventions is a system for temperature stabilization of the foundations of structures on permafrost [patent for invention RU 2416002 C1, publ. 04/10/2011, IPC: E02D 3/115], containing a water trap, surge vessel connected to the condenser and connected to them via pipelines supplying and discharging the coolant, and an evaporator located in the bedding of the base soil. The known system contains an additional evaporator with a piping system and a water seal. Both evaporators are placed evenly over the entire area of filling the soil of the base, equipped with a layer of thermal insulation, and are connected via pipelines through their outlet ends to the upper points of the surge vessel. The leading ends of the primary and secondary evaporators are connected at the lower point of the condenser and the lower point of the equalization vessel, respectively, through the corresponding hydraulic locks.

The disadvantages of the closest analogue include the use of liquid refrigerants, the high cost and metal consumption of the system for temperature stabilization of the foundations of structures on permafrost soils, which are formed due to the significant number of units and assemblies used, which also makes them insufficiently reliable during operation.

The problem to which the claimed group of inventions is directed is reliable temperature stabilization of permafrost and / or weak soils of the foundations of the objects of the pipeline system.

The technical result of the claimed group of inventions is to increase the efficiency of conservation of permafrost soils or freezing weak soils of the foundations of pipeline system objects to ensure safety during the designated period of operation under design conditions.

This problem is solved, and the technical result is achieved by the fact that the thermal stabilization device of permafrost soils contains at least two soil thermal stabilizers based on two-phase thermosyphons, including an aboveground condenser part and underground transport and evaporation parts, and at least one heat-conducting element made in the form of a plate from heat dissipating material with a thermal conductivity of at least 5 W / m⋅K, with at least two soil heat stabilizers installed in baa side of the pipeline underground installation, and at least one heat transfer member mounted under the thermally insulating material separating pipe underground laying of roofing permafrost and has openings for connection to the evaporator part of at least two ground heat stabilizers.

The heat-dissipating material is a heat-dissipating polymer composite having a heat conductivity coefficient of 5-15 W / m⋅K.

, связанном с радиусом r зоны замерзания грунта термостабилизатора следующим соотношением:

.Thermostabilizers of soil are installed from the axis of the underground pipeline at a distance

associated with the radius r of the soil freezing zone of the heat stabilizer by the following ratio:

.

The laying edge of the heat-conducting element is separated from the place of its connection with the evaporation part of the soil heat stabilizer at a distance of 0.2-0.3 r.

In addition, this problem is solved, and the technical result is achieved due to the fact that in the method of thermal stabilization of permafrost soil, excavation of thawed soil is carried out at the pipeline laying section to the depth of the roof of the permafrost soil, laying of the sand layer on the roof of the permafrost soil is carried out on the sand layer at least one heat-conducting element made in the form of a plate of heat-dissipating material with a thermal conductivity of at least 5 W / m⋅K is laid on at least one heat-conducting element, heat-insulating material; fill the excavation with thawed soil; at least two soil heat stabilizers are installed on both sides of the underground pipeline, based on two-phase thermosyphons, including an aboveground condenser part and underground transport and evaporation parts, and openings are made in the heat-conducting element for connecting with the evaporation parts of at least two soil heat stabilizers.

As a heat-dissipating material, a heat-dissipating polymer composite is used having a heat conductivity coefficient of 5-15 W / m⋅K.

, связанном с радиусом r зоны замерзания грунта термостабилизатора следующим соотношением:

.Thermostabilizers of soil are installed from the axis of the underground pipeline at a distance

associated with the radius r of the soil freezing zone of the heat stabilizer by the following ratio:

.

The edge of the heat-conducting element is placed from the place of its connection with the evaporative part of the soil heat stabilizer at a distance of 0.2-0.3 r.

The claimed group of inventions is illustrated by drawings (Fig. 1, Fig. 2), which depict:

FIG. 1 - section of the underground pipeline (top view);

FIG. 2 - section of the underground pipeline (longitudinal section),

and the positions indicated:

1 - underground pipeline;

2 - roof of permafrost soils;

3 - sand layer;

4 - heat-conducting element;

5 - thermal insulation material;

6 - thawed soil;

7 - soil thermal stabilizer.

In the particular case of the implementation of the claimed group of inventions, the device for thermal stabilization of permafrost soils may contain two thermal stabilizers of soil 7 installed opposite each other on both sides of the pipeline of the underground gasket 1, and a heat-conducting element 4 placed across the axis of the pipeline between the evaporative parts of thermostabilizers of soil 7. In addition, a device for thermal stabilization of permafrost soils may contain two or more heat-conducting elements 4 located across the axis of the pipeline between the evaporative parts of two or more pairs of soil thermal stabilizers installed opposite to each other 7.

, значение которого для гарантированного промораживания грунта в зоне прокладки трубопровода выбирают из диапазона

, где r - радиус зоны замерзания грунта термостабилизатора 7 при среднезимней температуре минус 15°C. Параметр r зависит от выбора конкретного типа термостабилизатора грунта 7. В частности, при использовании известных термостабилизаторов грунта, радиус зоны замерзания грунта при среднезимней температуре минус 15°C будет находиться в диапазоне 1-1,5 м.Thermostabilizers of the soil 7 are made on the basis of two-phase thermosiphons, including the aboveground upper condenser part and the underground middle transport and lower evaporation parts. Thermostabilizers of soil 7 are distant from the axis of the pipeline underground 1 for a distance

, the value of which for guaranteed freezing of soil in the area of the pipeline is selected from the range

where r is the radius of the soil freezing zone of the stabilizer 7 at a mid-winter temperature of minus 15 ° C. The parameter r depends on the choice of a particular type of soil thermal stabilizer 7. In particular, when using known thermal stabilizers of soil, the radius of the zone of soil freezing at an average winter temperature of minus 15 ° C will be in the range of 1-1.5 m.

The heat-conducting element 4 is made in the form of a plate of heat-dissipating material having a thermal conductivity of 5-15 W / m /K, and is preferably resistant to thermal effects up to 250 ° C and chemical influences. As a material with such properties, a heat-dissipating polymer composite can be used - granular plastic, unlike ordinary plastics, which has the ability in principle to conduct heat better (10-100 times) and transfer (dissipate) it into the environment. In a preferred embodiment, the plate of the heat-conducting element 4 can be made of long pipes made of a heat-dispersing polymer composite rigidly interconnected along the entire length along contacting generators.

The heat-conducting element 4 is installed under the heat-insulating material 5, which separates the pipeline of the underground gasket 1 from the roof of permafrost soils 2, and has openings for connecting with the evaporation parts of at least two soil heat stabilizers 7. Extrusion foam polystyrene can be used as the heat-insulating material 5 (for example, TechnoNICOL company). The laying edge of the heat-conducting element 4 is separated from the place of its connection with the evaporation part of the soil thermal stabilizer 7 by a distance of 0.2-0.3 r, where r is the radius of the soil freezing zone of the thermal stabilizer, which ensures reliable preservation of the soil of the foundations of the pipeline system objects in the permafrost state.

The claimed method of thermal stabilization of permafrost soils is as follows.

Initially, excavation of thawed soil 6 is carried out in the area of underground laying of pipeline 1 to the depth of the roof 2 of permafrost soils. Then the sand layer 3 is laid with a thickness of 100 to 150 mm on the roof of 2 permafrost soils and one or more heat-conducting elements 4 are made on the sand layer 3, made in the form of plates of heat-dissipating material with a thermal conductivity of at least 5 W / m⋅K. Openings (not shown) are made in the heat-conducting element 4 for connecting to the evaporative parts of the soil heat stabilizers 7. The laying edge of the heat-conducting element 4 is located at a distance of 0.2-0.3 r from the place of its connection with the evaporation part of the soil heat stabilizer 7, where r is the radius zones of soil freezing of the heat stabilizer. As a heat-dissipating material, a heat-dissipating polymer composite is used having a heat conductivity coefficient of 5-15 W / m⋅K.

от оси трубопровода подземной прокладки 1 в отверстия в теплопроводящем элементе 4 термостабилизаторы грунтов 7 на основе двухфазных термосифонов, включающих надземную конденсаторную часть и подземные транспортную и испарительные части. Расстояние

связано с радиусом r зоны замерзания грунта термостабилизатора соотношением

.After that, heat-insulating material 5 with a thickness of 100-200 mm is laid on the heat-conducting element 4. In conclusion, fill the excavation with melt soil 6 and install on both sides at a distance

from the axis of the pipeline of the underground gasket 1 into the holes in the heat-conducting element 4, soil heat stabilizers 7 based on two-phase thermosyphons, including the aboveground condenser part and the underground transport and evaporation parts. Distance

is connected with the radius r of the soil freezing zone of the heat stabilizer by the ratio

.

During the operation of the soil heat stabilizers 7 in the winter, heat is transferred through the heat-conducting element 4, which leads to a more efficient distribution of negative temperatures over the area occupied by the heat-conducting element 4, and to faster and more uniform cooling of the soil under the underground pipeline 1.

Example

When implementing the claimed method of thermal stabilization of permafrost soils and when using the claimed device for thermal stabilization of permafrost soils in winter, the radius of the soil freezing zone of the thermal stabilizer was measured in the presence of a heat-conducting element from a heat-dispersing polymer composite, the results of which are shown in table 1.

The measurements showed that even at an ambient temperature of minus 15 ° C, the radius of the soil freezing zone of the heat stabilizer in the presence of a heat-conducting element installed in accordance with the claimed method almost doubles: 2.65 m in the presence of a heat-conducting element, against 1-1.5 m when using only thermostabilizer.

Thus, when using the claimed group of inventions, an increase in the efficiency of conservation of permafrost soils or freezing of soft soils of the foundations of pipeline system objects is achieved to ensure safety during the designated period of operation under design conditions.

Claims (15)

1. The device for thermal stabilization of permafrost soils, characterized in that it contains at least two soil heat stabilizers based on two-phase thermosyphons, including an above-ground condenser part and underground transport and evaporation parts, and at least one heat-conducting element made in the form of a plate of heat-dissipating material with a thermal conductivity of at least 5 W / m⋅K, with at least two soil heat stabilizers installed on both sides of the underground pipeline rock-laying, and at least one heat-conducting element is installed under the heat-insulating material separating the underground laying pipeline from the roof of permafrost soils, and has openings for connecting to the evaporative parts of at least two soil heat stabilizers. 2. The device according to claim 1, characterized in that the heat-dissipating material is a heat-dispersing polymer composite having a thermal conductivity of 5-15 W / m⋅K. 3. The device according to p. 1, characterized in that the thermostabilizers of the soil are installed from the axis of the underground pipeline at a distance

associated with the radius r of the soil freezing zone of the heat stabilizer by the following ratio: 0.7 r≤

≤r. 4. The device according to p. 1, characterized in that the edge of the heat-conducting element is separated from the place of its connection with the evaporative part of the soil heat stabilizer at a distance of 0.2-0.3 r. 5. The method of thermal stabilization of permafrost soils, which consists in the fact that - carry out the excavation of thawed soil at the site of the pipeline to the depth of the roof of permafrost soils; - carry out the laying of the sand layer on the roof of permafrost soils; - lay on the sand layer at least one heat-conducting element made in the form of a plate of heat-dissipating material with a thermal conductivity of at least 5 W / m⋅K; - stack on at least one heat-conducting element, heat-insulating material; - carry out filling the excavation with thawed soil; - install on both sides of the underground pipeline at least two soil heat stabilizers based on two-phase thermosyphons, including the aboveground condenser part and the underground transport and evaporation parts; - moreover, holes are made in the heat-conducting element for connecting with the evaporative parts of at least two soil heat stabilizers. 6. The method according to p. 5, consisting in the fact that as a heat dissipating material using heat dissipating polymer composite having a coefficient of thermal conductivity of 5-15 W / m⋅K. 7. The method according to p. 5, which consists in the fact that the heat stabilizers of the soil are installed from the axis of the pipeline underground laying at a distance

associated with the radius r of the soil freezing zone of the heat stabilizer by the following ratio: 0.7 r≤

≤r. 8. The method according to p. 5, namely, that the edge of the heat-conducting element is placed from the place of its connection with the evaporative part of the soil heat stabilizer at a distance of 0.2-0.3 r.

Images