DE102016009008A1 - Method and apparatus for freezing ground adjacent to a shaft by means of a liquefied gas - Google Patents

Abstract

The invention relates to a method for freezing earth adjacent to a shaft (10) by means of a liquefied gas (F), the liquefied gas (F) being provided in a supply tank (21) positioned outside the shaft (10) from the supply tank (21) via at least one surge tank (23) and at least one connecting line (24) in at least one LPG freezing lance (22) is introduced, wherein by means of the at least one LPG freezing lance (22) a frost body (14) is cooled, and wherein in the at least one surge tank (23) a liquid column formed by the liquefied gas (F) is interrupted. The invention further relates to a device (20) having at least one supply container (21) for receiving a liquefied gas (F), a liquid gas freezing lance (22) and at least one expansion tank (23), wherein the supply container (21) via the at least one Equalizing tank (23) and via at least one downstream of the surge tank (23) arranged connecting line (24) with the liquid-gas freezing lance (22) can be brought into flow communication.

Description

The invention relates to a method and a device for freezing a shaft, in particular a deep shaft, adjacent ground (also referred to as ground freezing) by means of a liquefied gas.

In civil engineering and shaft construction are used in the prior art Bodengefrierverfahren in which the soil is solidified by artificial freezing of the water contained in the soil. In this case, a frost body is formed, the z. B. stabilizes the shaft bottom for further drilling and makes water impermeable.

In known ground freezing method, among other things, the brine cooling is used. In this case, a refrigerant in the form of a brine (in particular CaCl ₂ ) is guided in pipes to the icing, wherein the brine is tempered by means of a refrigeration system. By means of this method, the ground can be frozen with groundwater currents of up to 2 m / day.

As an alternative to brine cooling, according to the state of the art in the case of bottom freezing, cooling with cryogenic liquefied gases, such as liquid nitrogen or liquid air, is used. In particular, this method enables ground freezing with groundwater currents of up to 12 m / day.

Furthermore, the cooling with cryogenic liquefied gases is also used in combination with the brine cooling, wherein different areas of a brine frost body are created by supporting with a liquid gas icing. In this case, for example, a brine plant is operated in the protection of a liquid gas freezing in order to create the frost body with larger groundwater flows. After forestry production, the Flüssiggasvereisung can be stopped, the brine ice maintains the frost body.

In addition to the occurrence of groundwater currents also defects of the frost body can be repaired or closed by means of liquid gas icing according to the prior art. This is particularly necessary if other customary in specialist civil engineering measures to seal the defect fail.

In the liquefied gas icing, copper pipes, in particular heat-insulated copper pipes or rigid or flexible vacuum-insulated pipes, in particular vacuum corrugated metal hoses, are frequently used for the supply of liquefied gas according to the prior art.

Deep shaft construction is subject to the usual depths of 600-1500 m and high geodetic pressures which such copper pipes and standard LPG pipes can not withstand. For this reason, the prior art methods do not permit bottom freezing by means of liquified gas at great depths. This is an obstacle for the pit construction when groundwater flows occur at a speed of more than 2 m / day or in the formation of imperfections of the frost body.

The object is therefore to provide a method and a device for freezing of soil adjacent to a shaft by means of a liquefied gas, which is improved in view of the aforementioned problem.

This object is achieved by the method according to claim 1 and the device according to the invention according to claim 6. Embodiments of the method are given in the dependent claims 2 to 5 and embodiments of the device are specified in the subclaims 7 to 10.

According to a first aspect of the invention, there is provided a method for freezing liquor gas to a well, in particular a well, adjacent soil. In the method, the liquefied gas is provided in a supply container positioned outside the shaft, in particular at a top edge of the shaft, from the supply tank via at least one expansion tank and via at least one connecting pipe arranged downstream of the at least one expansion tank into at least one, in particular in the shaft positioned, LPG freezing lance initiated. By means of the at least one liquefied-gas freezing lance, a frost body arranged on the bottom of the shaft and / or on the circumference of the shaft is cooled, wherein in the at least one expansion tank a liquid column formed by the liquefied gas for reducing the gravitational pressure of the liquefied gas prevailing in the at least one connecting line is interrupted.

Due to the inventive reduction of the pressure prevailing on the at least one connecting line gravity pressure advantageously the mechanical load of the connecting lines is reduced, whereby even with large Abteuftiefen favorable standard connecting lines can be used.

In one embodiment of the method according to the invention, the frost body becomes indirect cooled by the liquefied gas, in particular a closed to the frost body outer tube of the liquid-gas freezing lance is introduced into the frost body, and wherein the liquefied gas is introduced into a space enclosed by the outer tube shell space, so that the outer tube is cooled by the liquefied gas and the Frost body is cooled by the cold outer tube.

In an alternative embodiment, the frost body is cooled directly by the liquefied gas, wherein in particular the liquefied gas is applied to the frost body.

In a further embodiment, the process is carried out batchwise. In this case, the liquefied gas is first introduced, for example, into a first expansion tank, then introduced successively into further expansion tank and finally fed to the at least one liquid gas freeze lance.

In an alternative embodiment, the process is carried out continuously. The liquefied gas is introduced, for example via an input valve in a respective expansion tank and simultaneously withdrawn via an outlet valve from the surge tank, wherein the flow rate of flowing through the valves liquefied gas is adjusted such that no continuous liquid column is present within the surge tank.

The placement of the supply tank at the upper edge of the terrain and the liquefied gas to the liquefied gas freezing lance have the advantage that the process can also be used with small shaft diameters (eg in the region of 7 m). In addition, additional safety requirements are avoided when positioning the supply container directly to the sole.

The use of a plurality of connecting lines with compensating containers positioned therebetween has the advantage that the geodetic pressure acting on the connecting lines is significantly reduced by the interruption of the liquid column in the compensating containers. For example, when using a single connecting line without expansion tank, a supply tank pressure of 10 bar and a depth of 800 m, a geodetic pressure of about 90 bar would load on the respective connecting line. When positioning compensating containers according to the invention at a distance of about 150 m along the depth of the shaft, on the other hand, only a pressure of about 25 bar would load on the respective connecting line, which corresponds to the permissible operating pressure of vacuum-insulated lines which are normally used. The ability to use standard leads advantageously reduces the cost of the method of the invention as compared to prior art methods.

At low flow rates of the system, eg. As in an icing of smaller imperfections of the frost body or at relatively warm exhaust gas temperatures of about -60 ° C, it often occurs in the prior art method to tear off the liquid column and thus to an interruption of the liquid gas supply. The method according to the invention can advantageously be used to ensure the constant supply of liquefied gas to the at least one LPG freezing lance under such conditions.

By means of the method according to the invention, it is possible to freeze groundwater flows occurring in deep wells in the range of more than 2 m / day with liquefied gas. As a result, additional process reliability in the creation of deep wells is provided in a cost-effective manner, in particular when unknown geological defects and / or groundwater intrusion occur. In addition, the method according to the invention can be realized at low levels of technical complexity in the case of surprising occurrence of groundwater currents at great depths than comparable measures in brine upgrading such as increasing the pump capacity and / or setting additional boreholes and brine icing lances.

The inventive method can also be used for long supply routes z. B. tunnel bores, cross passages with far away launch shaft or other Mienenvortrieben be used.

According to a further embodiment, the bottom of the shaft has a depth of 150 m to 1500 m, in particular 300 m to 1500 m.

According to another embodiment of the method, the liquefied gas is liquid nitrogen (LIN).

According to a further embodiment of the method, the liquefied gas is introduced via a plurality of expansion tanks into the at least one liquid gas freezing lance, wherein the expansion tanks can be brought into fluid communication with each other in series, so that in each expansion tank, the liquid column formed by the liquefied gas to reduce the is interrupted in the respective downstream arranged connecting line prevailing gravitational pressure of the liquefied gas. Preferably, two are each adjacent expansion tank via a connecting line with each other fluidly connected or -verbindbar.

By using several expansion tanks, a supply of liquefied gas can also be achieved in larger depths with standard connection lines.

According to a further embodiment of the method, a gaseous phase formed by evaporation of the liquefied gas is withdrawn from at least one expansion tank.

The formation of such a gaseous phase comes about in particular by heat losses in the connecting lines and by the pressure drop during the introduction of the liquefied gas into the surge tank. By withdrawing the gaseous phase, this is advantageously removed from the system.

In accordance with a further embodiment of the method, the gaseous phase is fed to an exhaust system of the at least one liquid gas freeze lance.

According to a further embodiment of the method, the gaseous phase is blown off at the upper edge of the terrain.

According to a further embodiment of the method, the frost body was previously produced by freezing the soil by means of a brine, in particular by a brine cooling.

According to another embodiment, the shaft has on its outer circumference a brine-freezing body produced by the brine cooling, wherein the brine-freezing body at the bottom of the shaft passes into the frost body, and wherein the frost body is enhanced by means of the liquid-gas freezing lance.

According to a further embodiment of the method, the pressure in the at least one expansion tank (or in the plurality of expansion tanks) and / or in the at least one connecting pipe (or in the plurality of connecting pipes) is controlled or regulated.

In this way, advantageously, the supply of liquefied gas to at least one liquid gas freezing lance can be maintained at different conditions.

According to a second aspect of the invention, there is provided apparatus for freezing soil adjacent to a well by means of a liquified gas, in particular for carrying out the process according to the first aspect of the invention. In this case, the device comprises at least the following components: a supply container for receiving a liquefied gas, at least one LPG freezing lance for cooling a frost body by means of the liquefied gas and at least one surge tank for receiving the liquefied gas. The supply tank can be brought into fluid communication with the at least one liquid gas freezing lance via the at least one expansion tank and at least one connecting pipe arranged downstream of the at least one expansion tank, so that a liquid column formed by the liquefied gas is available in the at least one expansion tank for reducing the at least a connecting line prevailing gravitational pressure of the liquefied gas can be interrupted.

In particular, the liquid-gas freezing lance has a closed outer tube which encloses a jacket space, wherein in the shell space an inner tube for introducing liquefied gas is arranged in the shell space, so that the outer tube is cooled by means of the introduced liquefied gas, and wherein the liquid-gas freeze lance is designed to cool a frost body by means of the cold outer tube.

Alternatively, the LPG freeze lance may also be configured to cool a frost body by directly applying a liquefied gas to the frost body.

According to another embodiment, the liquefied gas in the supply tank to a pressure of 2 bar to 14 bar.

According to a further embodiment, the at least one connecting line is designed as a rigid or flexible vacuum-insulated pipe, in particular as a vacuum corrugated metal hose, as a copper pipe, in particular as a heat-insulated copper pipe, or as a stainless steel pipe, in particular as a heat-insulated stainless steel pipe.

According to one embodiment, the at least one connecting line in each case has a length of 25 m to 200 m.

According to a further embodiment, the at least one connecting line is flexible.

According to a further embodiment, the at least one connecting line is thermally insulated from its respective surroundings, in particular vacuum-insulated.

According to a further embodiment, the at least one expansion tank has a maximum filling volume of 0.1 m ³ to 10 m ³ .

According to another embodiment, the at least one expansion tank is thermally insulated from its surroundings, in particular vacuum-insulated or conventionally insulated. A conventional insulation can, for. B. be realized by a foam insulation (FEF, PUR or similar insulation).

According to a further embodiment, the device has a plurality of expansion tanks, which are in fluid communication with each other in series.

According to a further embodiment, the at least one expansion tank has an inlet valve and an outlet valve, wherein the inlet valve is designed to close or restrict a flow connection between a connecting line arranged upstream of the at least one expansion tank and the expansion tank, and wherein the outlet valve is designed for this purpose is to close or restrict a flow connection between the downstream of the at least one expansion tank arranged connecting line and the surge tank, and wherein the liquefied gas is introduced into the at least one surge tank by means of the upstream of the at least one surge tank connecting line, and wherein by means of the downstream of the At least one expansion tank arranged connecting line, the liquefied gas from the at least one expansion tank is removable.

By the input and output valves of the pressure in the surge tanks and / or the connecting lines pressure can be advantageously regulated.

According to a further embodiment, the at least one expansion tank each have a gas outlet opening, wherein by means of the gas outlet opening a gaseous phase of the liquefied gas can be withdrawn from the expansion tank, wherein in particular the expansion tank has a gas outlet valve which forms the gas outlet opening.

According to a further embodiment, the device has a device for controlling and / or regulating the at least one input valve and / or the at least one output valve and / or the at least one gas outlet valve, so that by means of the device in the at least one expansion tank and / or in the pressure prevailing at least one connecting line can be controlled and / or regulated.

In particular, the device for controlling the at least one input valve and / or the at least one output valve and / or the at least one gas outlet valve is designed as a two-point controller or continuous controller, which is consumed as a function of the amount of liquefied gas consumed by the at least one LPG freezer lance. controls the input and / or output and / or gas outlet valves.

Further details and advantages of the invention will be explained by the following description of an embodiment with reference to figures. Show it:

1 a schematic representation of a shaft with a device according to the invention for bottom freezing by means of a liquefied gas to a sole of a shaft, and

2 a schematic representation of a liquid gas freezing lance.

In detail, the shows 1 a shaft 10 with a depth of cut 13 (short: depth 13 ), where the shaft 10 in the direction of its depth 13 between a top surface 11 and a sole 12 extends. Furthermore, there is a frost body 14 shown from frozen soil, the frost body 14 the shaft 10 at the sole 12 and on the perimeter of the shaft 10 surrounds. At the circumference of the shaft 10 is an optional brine freezing lance 15 shown, which is adapted to the frost body 14 to create or maintain by cooling the soil.

At or in the shaft 10 is a device according to the invention 20 arranged for bottom freezing by means of a liquefied gas F. The device 20 has a supply tank 21 on, which is at least partially filled with a liquefied gas F, in particular liquid nitrogen. In particular, it is the supply tank 21 around a heat-insulated against the environment Kryotank.

The device 20 also has a liquid gas freezing lance 22 on that from the supply tank 21 can be supplied with liquefied gas F. By means of the liquid gas freezing lance 22 can be cooled by the liquefied gas F of the soil, so that the soil with a suitable application of the LPG freezing lance 22 freezes. This is the LPG freezing lance 22 especially in a frost body 14 brought in. In the presentation of the 1 is the LPG freezing lance 22 at the sole 12 of the shaft. However, other arrangements are conceivable, in particular, an arrangement of the liquid-gas freezing lance on the circumference of the shaft 10 ,

The LPG freezing lance 22 may in one embodiment of the invention for indirect cooling of the frost body 22 over to the frost body 14 closed cold outer tube 220 be educated. Here is the LPG freezing lance 22 in particular as shown in FIG 2 executed. Alternatively, the LPG freeze lance 22 be trained to the frost body 14 by applying the liquefied gas F to the frost body 14 to cool directly. In both alternative embodiments, the frost body may 14 be generated by a brine cooling and / or additionally cooled.

The device 20 also has a plurality of expansion tanks 23 on. In the 1 are three expansion tanks 23a . 23b . 23c but the invention is not limited to this number.

The supply tank 21 is over an upstream of the first expansion tank 23a arranged connection line 24 with a first expansion tank 23a which is in the shaft 10 is arranged, can be brought into fluid communication, so that liquefied gas F by means of the connecting line 24 from the supply tank 21 in the first expansion tank 23a can be initiated.

By means of a supply valve 29 can the flow connection between the supply tank 21 and the first expansion tank 23a throttled or interrupted.

The first expansion tank 23a has an inlet valve 25 and an outlet valve 26 on, with the connecting line 24 between the supply tank 21 and the first expansion tank 23a with the input valve 25 of the first expansion tank 23a is in flow communication. Via the inlet valve 25 may be the flow of the connection line 24 in the first expansion tank 23a inflowing liquefied gas F be throttled or the flow connection can by means of the input valve 25 to be interrupted.

Furthermore, the first expansion tank 23a an outlet valve 26 on, being the first expansion tank 23a over the outlet valve 26 and a connection line 24 with an input valve 25 a second expansion tank 23b is connected so that liquefied gas F from the first expansion tank 23a over the connecting line 24 in the second expansion tank 23b can be initiated. The second expansion tank 23b is by means of its outlet valve 26 over another connecting line 24 with the input valve 25 a third expansion tank 23c connected. The third expansion tank 23c is in the embodiment shown here about its output valve 26 by means of a connecting line 24 with one on the sole 12 of the shaft 10 positioned LPG freezing lance 22 connected. Thus, from the supply tank 21 over the expansion tank 23a . 23b . 23c liquefied gas F into the LPG freezing lance 22 be initiated. The expansion tank 23a . 23b . 23c are connected in series, so that the liquefied gas F, the expansion tank 23a . 23b . 23c flows through successively.

The connection lines 24 are especially as rigid or flexible vacuum insulated lines, eg. B. vacuum corrugated tubing executed.

The second expansion tank 23b is at a greater depth in the shaft 10 positioned as the first expansion tank 23a and the third expansion tank 23c is located at a greater depth than the second surge tank 23b , Up to the position of the inlet valve 25 of the first expansion tank 23a Heavy pressure is applied to the connecting line 24 between the supply tank 21 and the first expansion tank 23a , which is the height of the liquid column of the liquefied gas F from the ground level 11 or the level of the supply tank 21 up to the corresponding position of the connecting line 24 depends. By means of the input valve 25 is the flow connection between the with the input valve 25 connected connection line 24 and the first expansion tank 23a interrupted or throttled so that the liquid column in the first expansion tank 23a interrupted. This puts a load on the connection line 24 between the first expansion tank 23a and the second surge tank 23b only a geodetic pressure due to the height of the liquid column between the first expansion tank 23a and the corresponding position of the connection line 24 ,

In the second expansion tank 23b and in the third expansion tank 23c also breaks off the liquid column of the liquefied gas F, so that several separate liquid columns between the respective surge tanks 23 be formed. This puts a strain on the respective connecting lines 24 a correspondingly reduced pressure in comparison to the pressure, which in the case of a continuous liquid column between the supply container 21 and the LPG freeze lance 22 at the corresponding position of the corresponding connection line 24 would prevail.

The device 20 also has a facility 28 for controlling and / or regulating, via corresponding electrical lines 28a with the input valves 25 and the outlet valves 26 is connected, allowing an opening and closing of the input and output valves 25 . 26 the expansion tank 23 and / or throttling the flow of liquefied gas F through the input and output valves 25 . 26 by means of the device 28 is controllable or controllable. Opening and closing the supply valve 29 can also by means of the device 28 be controlled or regulated.

The expansion tank 23 continue to each have a gas outlet opening 27 on, by means of the one by evaporation of the liquefied gas F in the respective expansion tank 23 resulting gaseous phase G from the expansion tank 23 can be deducted. In particular, the expansion tank 23 a gas outlet valve 27a on that the gas outlet 27 forms. Optionally, the gas outlet valve is optional 27a by means of the device 28 controllable or controllable.

The 2 shows a liquefied petroleum freeze lance 22 for indirect cooling of a frost body 14 , wherein the liquid-gas freezing lance 22 partly in the frost body 14 is arranged. The LPG freezing lance 22 indicates to the frost body 14 closed outer tube 220 on which a mantle room 222 includes. In the mantle room 222 is an inner tube 221 arranged. By means of the inner tube 221 can liquefied gas F into the mantle space 222 be initiated, causing the outer tube 220 is cooled. The frost body 14 is due to heat conduction from the cold outer tube 220 on the frost body 14 cooled, where in the shell space 222 located liquefied gas F is heated and evaporated in particular to form a gaseous phase G. The gaseous phase G is by means of a gas line 223 from the LPG freezing lance 22 deducted. In the described process, the outer tube acts 220 especially as a heat exchanger.

LIST OF REFERENCE NUMBERS

10

shaft

11

ground level

12

sole

13

depth

14

Frost body

15

Brine freezing lance

20

contraption

21

supply vessel

22

LPG freezing lance

220

outer tube

221

inner tube

222

shell space

223

gas pipe

23

surge tank

23a

First equalization tank

23b

Second expansion tank

23c

Third equalization tank

24

connecting line

25

inlet valve

26

outlet valve

27

Gas outlet

27a

Gas outlet valve

28

Device for control and / or regulation

28a

Electrical line

29

supply valve

F

Liquefied gas

G

Gaseous phase

Claims (10)

Method for freezing to a shaft ( 10 ) adjacent soil by means of a liquefied gas (F), wherein the liquefied gas (F) in an outside of the shaft ( 10 ) positioned supply containers ( 21 ) and from the supply container ( 21 ) via at least one expansion tank ( 23 ) and at least one downstream of the at least one expansion tank ( 23 ) connecting line ( 24 ) in at least one LPG freezing lance ( 22 ) is introduced, wherein by means of at least one LPG freezing lance ( 22 ) on the sole ( 12 ) of the shaft ( 10 ) and / or on the circumference of the shaft ( 10 ) arranged frost bodies ( 14 ) is cooled, and wherein in the at least one surge tank ( 23 ) a liquid column formed by the liquefied gas (F) for the reduction of in the at least one connecting line ( 24 ) prevailing gravitational pressure of the liquefied gas is interrupted. The method of claim 1, wherein the liquefied gas (F) is liquid nitrogen (LIN). Method according to claim 1 or 2, wherein the liquefied gas (F) is conveyed via a plurality of expansion tanks ( 23 ) into the at least one LPG freeze lance ( 22 ), the reservoirs ( 23 ) in fluid communication with each other in series. Method according to one of the preceding claims, wherein at least one expansion tank ( 23 ) is withdrawn by vaporization of the liquefied gas (F) formed gaseous phase (G). Method according to one of the preceding claims, wherein the frost body ( 14 ) was previously generated by freezing the soil by means of a brine. Contraption ( 20 ) for freezing to a shaft ( 10 ) adjacent soil by means of a liquefied gas (F), the device ( 20 ) comprises at least the following components: - a supply container ( 21 ) for receiving a liquefied gas (F), - at least one LPG freezing lance ( 22 ) for cooling a frost body ( 14 ) By means of the liquefied gas (F), characterized in that the device ( 20 ) at least one expansion tank ( 23 ) for receiving the liquefied gas (F), wherein the supply container ( 21 ) via the at least one expansion tank ( 23 ) and at least one downstream of the at least one expansion tank ( 23 ) connecting line ( 24 ) with the at least one LPG freeze lance ( 22 ) can be brought into fluid communication, so that in the at least one surge tank ( 23 ) a liquid column formed by the liquefied gas (F) for the reduction of in the at least one connecting line ( 24 ) prevailing gravitational pressure of the liquefied gas can be interrupted. Contraption ( 20 ) according to claim 6, characterized in that the device ( 20 ) a plurality of expansion tanks ( 23 ) in fluid communication with each other in series. Contraption ( 20 ) according to claim 6 or 7, characterized in that the at least one expansion tank ( 23 ) each have an input valve ( 25 ) and an outlet valve ( 26 ), wherein the input valve ( 25 ) is adapted to a flow connection between an upstream of the at least one surge tank ( 23 ) arranged connecting line ( 24 ) and the expansion tank ( 23 ) or to shut off, and the outlet valve ( 26 ) is adapted to a flow connection between the downstream of the at least one surge tank arranged connecting line ( 24 ) and the expansion tank ( 23 ), and wherein by means of the upstream of the at least one expansion tank ( 23 ) arranged connecting line ( 24 ) the liquefied gas (F) into the at least one expansion tank ( 23 ), and wherein by means of the downstream of the at least one expansion tank ( 23 ) arranged connecting line ( 24 ) the liquefied gas (F) from the at least one expansion tank ( 23 ) is removable. Contraption ( 20 ) according to one of claims 6 to 8, characterized in that the at least one expansion tank ( 23 ) each have a gas outlet opening ( 27 ), wherein by means of the gas outlet opening ( 27 ) a gaseous phase (G) of the liquefied gas from the at least one surge tank ( 23 ) is removable, wherein in particular the at least one expansion tank ( 23 ) a gas outlet valve ( 27a ), which the gas outlet opening ( 27 ). Contraption ( 20 ) according to claim 8 or 9, characterized in that the device ( 20 ) An institution ( 28 ) for controlling and / or regulating the at least one input valve ( 25 ) and / or the at least one output valve ( 26 ) and / or the at least one gas outlet valve ( 27a ), so that by means of the device ( 28 ) in the at least one surge tank ( 23 ) and / or in the at least one connecting line ( 24 ) prevailing pressure is controlled or regulated.

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