DE102009019287A1 - Method for heating up soil, associated plant and their use - Google Patents

Abstract

Method for heating soil with soil that is electrically heated using an inductive heating method in which the soil is heated by high-frequency electromagnetic fields in the range between 10 and 200 kHz. In an associated system for carrying out the method, at least one generator (60) for high frequency of predetermined frequency (f) in the kHz range, to which at least one inductor arrangement (10) with a forward conductor (15) and a return conductor (20) is connected, available. Advantageous use of the method or such a plant in the context of active environmental protection, in particular for reclamation contaminated with organic substances areas.

Description

The The invention relates to a method for heating soil with soil that is electrically heated. Besides it refers the invention to the associated system and to the use Such a system or such a method.

soils are heated for various purposes. In particular, contaminated Locations - such as B. hydrocarbon contaminated soils - be decontaminated by in situ process. There is a Auskoffern of the soil too expensive. Sometimes there is the contaminated Place under a structure that is not demolished but fully functional should stay.

Most of time it is desirable, the soil of z. B. 5 ° C to heat to 30 ... 40 ° C or more. This will be the microbial cerebral replacement of the targeted substances stimulated since the microbacteria find better conditions for activity at higher temperatures. As the temperature further increases, the mobility becomes the pollutants improved, making the use of complementary Procedure allows, for example, Bodenluftabsaugung.

comes one speaks in the latter method to the boiling point of the water one from a "stripping" process in which Water evaporation can be achieved even higher pollutant discharge can. By evaporation, a volume flow is excited, which on the volume increase water / steam based.

It may be the target of the decontamination strategy, all temperature ranges to approach and to hold in a timely manner biological, chemical and physical effects are exploited.

With the so-called. THERIS method (Hiester et al., Scientific Report No. VEG 05, Institute of Hydraulic Engineering, University of Stuttgart, 2003, No. 2003/14 - Final report on Phase II., http: //.bwplus.fzk.de/index_Projekte_datenbank.html ) is already known a method to expel liquid organic pollutants from soils by introducing solid heat sources. In this case, electric heaters, for example, for dielectric heating, using radio waves are used (s. Postdoctoral thesis H. Roland, Th. Bergakademie Freiberg 2006 ).

The Thermal processes generally use a dielectric or resistive heating process. In addition to these electrical procedures there There are also possibilities of a floor ventilation, where hot Air or steam is used.

The resistive process is applied in the stripping process so that Electrodes are brought into the ground. The electrodes will be connected to a voltage source, allowing through the ground a resistive resistance is formed. Disadvantage of the method is that the current seeks conductive paths in which the current density becomes highest and consequently dry out with reduction of electrical conductivity. Furthermore is at the electrodes with resistive contact resistance to calculate, with the u. U. a coking of the electrodes can occur. The method still requires a high number on vertical electrodes, which makes it impossible, for. B. under buildings without destroying the foundation to heat. Usually one takes 50 Hz or 60 Hz alternating or three-phase or direct current.

As may alternatively be mentioned for the above purpose also cartridge heaters are used, resulting in local heat distribution but rather uneven regarding the volume is and therefore has not been proven.

A better method is known to be the dielectric heating. Here, the dipoles are mainly the water dipole in vibration offset in a frequency range greater than 300 MHz, ideally at 2.45 GHz - as in microwave technology applied - the resonance frequency of the water dipole occurs. The resulting heat heats up the soil naturally existing water and consequently by further heat conduction also the other earths.

disadvantage The latter method is that also a high number of antennas is necessary because the penetration depth of the electromagnetic field is limited to the meter range and over the distance from the antenna, the field radially drops sharply.

All known methods have the disadvantage that undesirable Temperature gradients arise and thus the total heating runs inhomogeneously.

task The invention is therefore to provide a method and an associated Create facility. For this purpose, suitable applications are proposed become.

The object is achieved according to the invention for a method of the type mentioned by the measures of claim 1. An associated system is the subject of claim 11. An inventive use of such a system using the specified method is the content of claim 21. Advantageous developments of the method, the associated system and the related Ver Application are specified in the subclaims.

The present invention is an inductive heating method with a plant, such as the applicant with the DBP 10 2007 040 605 specially protected in connection with the extraction of oil sand.

The The present invention makes use of that which is described there in detail Inductive method used for heating near-surface earth area becomes. In this case, a suitable frequency in the range of 10 kHz to 200 kHz, which is generated by a converter. Of the Inverter feeds an inductor which runs lengthwise in two substantially parallel strands in the ground is introduced. This is done by a horizontal drilling method (so-called "horizontal directional drilling") a course drilled, which sets a loop for the inductor, which with their ends to the high-frequency power generator or Inverter is connected. It can in the horizontal bore suitable curvatures for the inductor lines be specified.

at The invention thus the soil according to its conductivity heated without contact. Due to the always existing alternating field around the Inductor induced eddy currents in the ground, which cause the warming. This effect has a penetration depth up to about 50 m and propagates itself further by no longer conductive points no eddy currents be generated. At first the inductor is the highest Power density, outwardly, the power density is reduced because of the volume to be heated, away from the inductor radially seen, gets bigger.

at The invention assumes that 1 kW up to 10 kW 20 kW per meter length of the inductor introduced into the ground becomes. It is depending on conductivity and volume a heating time of several months to years necessary. Through targeted introduction conductive solutions (eg saline or sea salt solution) is an increase of the effect in certain places or large volume possible.

in the Under the invention, the penetration depth by frequency and soil conductivity determines, whereby in the heated earth rich a heating profile can be adjusted. The more compact or concentrated the warming is to take place, the higher it must be the frequency can be chosen. This can be useful to the unwanted heating of steel reinforcements and piping systems of the structure.

Furthermore, a targeted, small-scale heating can take place by leading and returning conductors of the inductor loop at a small distance, for example from 2 to 5 m, are performed, which is exemplary in the older, not pre-published German patent application AZ 10 2008 044 953.9 the applicant is explained.

If a facility is used, as detailed in the older, not pre-published German patent application AZ 10 2008 044 955.5 is described in the applicant, the heating profiles can be adapted to the spatial requirements, taking into account the soil conductivity distribution in the decontamination by a suitable energization of an array of inductors. The inductor array can be energized variable in time.

Of the effect according to the invention has a penetration depth from up to approx. 50 m. It is particularly advantageous that now even under buildings or other locally difficult places a heating of the soil can be achieved, what with the thermal Methods of the prior art is not achievable.

The Heating according to the invention is effected without contact. The required area is extreme low. The new method can also be used with other methods of decontamination be combined.

With The invention thus provides a technology that is particularly can be used advantageously in the context of effective environmental protection is. Application examples of built-up terrain are Petrol stations, for non-built-up areas the renovation from military training areas or other with oil or the like organic substances of contaminated premises.

Further Details and advantages of the invention will become apparent from the following Description of the figures of exemplary embodiments with reference to FIG Drawing in conjunction with the claims.

It each show in a schematic representation

1 three-dimensional a preferred application of an inductive heating under the premises of a gas station,

2 a projection or a section along the line XX in 1 .

3 a plan view of extending in the ground inductor with varying distance from the return conductor,

4 a specific Schaltungsanord tion for heating soil to a predetermined temperature or for heating to specifiable, temporally and / or spatially variable temperature profiles using array-like inductor structures, and

5 a circuit arrangement for using a plurality of separate generators with different operating frequencies for use in the array-like inductor structure according to 4 ,

In The figures have the same parts or units or the same corresponding reference numerals. It will do so on the top already cited earlier German patent applications of the applicant referenced, their disclosure partially used becomes.

The aforementioned In the following, some figures become individual or groupwise described together.

1 shows a built-up premises as a potential application of the invention in the context of a targeted environmental protection. In 1 is the earth's surface with 1 denotes, for example, a site with a gas station 2 as an example of a functional building contains. In such an operating area, the soil of the soil is inevitably contaminated with hydrocarbon-rich organic contaminants during prolonged use of the plants.

For decontamination of the soil is now advantageously an inductive heating of the soil via an inductor 10 , which are below the building with an outgoing line 15 and a return 20 are guided substantially horizontally and against each other banana-shaped. Above the ground 1 There is a loop on one side 25 as a connection of the two inductor lines 15 . 20 and on the other hand, at least one high frequency generator / inverter 60 , The inductor lines 15 . 20 in built - up areas, it is possible to use wells that are guided essentially horizontally, which are located in 1 is not shown in detail. This is done with appropriate horizontal drilling technology ("horizontal drilling"), which is known in the art. Consider a cuboid 100 as a unit volume.

to economic implementation of the latter horizontal drilling technology must be noted that the radii of curvature of the holes do not get too small. Such specifications are given here Example with holes underneath the building must be taken into account.

2 gives a cut or a projection in the direction of the section line XX in 1 again. Recognizable in this representation - section parallel to the unit cuboid 100 out 1 - the underground soil 5 with the two inductor lines 15 . 20 which are located at a predetermined depth d from the earth's surface and have a defined distance a _{i between} them. The air area (so-called "Overburden") is in 2 with the reference number 6 marked and has no development in this illustration.

But as mentioned above specifically in 1 an application to a built-up area, where it is important to drill in the ground beneath the buildings, such as a gas station or a factory site, without their malfunction.

deviant from the latter application, but it may also be undeveloped Terrain, for example, an abandoned military training area, act. As the experience shows have been in the past just here, ignoring any environmental protection disposed of organic materials, d. H. buried in the ground or with appropriate viscosity simply drained into the soil.

Further Application examples are landfills or industrial wastes, which increasingly according to their intended purpose Use of environmentally sound use, for example residential purposes, should be fed without the soil completely must be replaced. Especially in such cases but before that, targeted environmental protection measures, such as which are described in detail in the present patent application.

In 3 is shown that in an arrangement accordingly 1 / 2 in this case guided in the ground induction cables 15 and 20 do not need to run parallel with constant distance. Rather, they have sections of different distances a _i , which can be adapted to the circumstances of the site. Depending on the geological conditions, they can have sections for an inductive interaction with one another and be guided very closely there, so that the magnetic fields compensate each other. Especially in the event that in the area 100 an obstacle 30 exists as a so-called "deaf" area, such. B. solid stone o. The like., There can be the parallel arrangement of the lines 15 / 20 To be around this area closely around and behind the obstacle 30 expand again to generate the inductive heating effect. Overall, in turn, results in a known manner, a conductor loop, which is particularly closed above ground, which is easy to achieve manufacturing technology.

When Inductor leads are used as multifilament leads in principle already in earlier applications of the Applicant are described above. In this case, a capacitive compensation, at the inductance of the lines connected in series Capacities compensated, will be made, with there is a given resonance length.

A corresponding plan view of such an inductor arrangement results 3 , There are a total of eight sections here I . II , ..., VIII with different distances a _{i of} the inductor lines 15 / 20 entered. It should be noted that for the sections I . II , ..., VIII each individual compensation measures of the lines to be carried out taking into account the changed resonance lengths.

In circuit arrangements for operating the inductors circuit arrangements are used, as already described in another context. This is exemplified by the 4 and 5 clarifies:
In 4 is shown in detail how four inductor pairs can be switched with temporally sequential current supply. It is with 60 again called the high frequency power generator whose outputs are on switching units 61 . 61 ' are given. The switching units 61 . 61 ' each have four different contacts, with the switching unit 61 at four inductors 11 . 12 . 13 . 14 as a lead and the switching unit 61 ' at four inductors 16 . 17 . 18 . 19 are connected as return conductors via the line connection 25 form the induction loop. A switching clock 62 provides for switching or switching on the generator voltage to the individual lines 11 to 14 respectively. 16 to 19 ,

The individual inductor lines 11 to 14 respectively. 16 to 19 are appropriate 1 in the earth station 100 arranged. On both sides of the earth station 100 are areas 105 present, which are not heated or little heated and phenomenologically represent the airspace. Furthermore, a connection line 25 connected to the ends of the inductors connecting the forward and return conductors. The connection line 25 can be arranged above or below ground.

With the latter arrangement, it is possible, each controlled to heat individual adjacent areas of Erdbodenstätte. This can be done in particular chronologically one after the other, ie sequentially. The switching clock 62 can do this by a separate control unit 63 be controlled, in particular the temperature T in the ground 100 considered. For example, in 2 Temperature sensors, not shown, are placed on the individual inductors or inductor lines in order to locally measure the respective temperatures T _i and to the control unit 63 to conduct the evaluation. It can thus be avoided in particular overtemperatures at the inductors.

But it is also possible, the temperatures locally at any point in the Erdbodenstätte 100 to be measured and taken into account when controlling the generators. It is essential that the power output of the generators changes and can be adapted to the respective requirements, which changes in the temporal warming phases of the deposit. This is particularly true because the time periods of warming are long, for example weeks and more.

In 5 is the arrangement according to 4 Modified to the effect that four high-frequency power generators 60 ' . 60 '' . 60 ''' and 60 '''' are present, which in pairs two of the inductors 11 to 14 respectively. 16 to 19 are controlled and in turn connected to each other via the connecting line.

The Connection of the inductors can be made above or below ground. With such an arrangement it is possible in particular four inductor pairs at the same time with different currents to energize at different frequencies.

An arrangement according to 4 can be modified so that different frequencies are used. This is in 5 shown, in turn, eight inductors 11 to 14 and 16 to 19 are arranged in the Erdbodenstätte parallel to each other. Two of the inductors 11 to 14 and 16 to 19 be from a separate generator 60 ' to 60 '''' driven. In this case, such generators are selected which generate different predefinable frequencies. For example, generator has 60 ' the frequency f ₁ , generator 60 '' the frequency f ₂ , generator 60 ''' the frequency f ₃ and generator 60 '''' the frequency f ₄ . By supplying currents of different frequencies, the individual regions are now selectively heated differently without there being extinction effects of the fields of adjacent inductors, ie the amounts of heating power of the inductor pairs operated with different frequencies behave additively.

• a: Bei Bestromung beispielsweise der Induktoren 1 bis 5 ergibt sich beispielsweise eine prozentuale Verlustverteilung von: OB 31,3%, Erdbodenstätte 45,5% und UB 23,2%.
• b: Bei gleichzeitiger Bestromung aller Induktoren ergibt sich dagegen: OB 24,2%, Erdbodenstätte 62,8% und UB 13,0%.

The examples showed that the Heizleistunasan parts in the ground 100 can be influenced by a differentiated energization of the inductors within predetermined limits. These proportions are given conclusively for an example examined in detail:

• a: When energizing, for example, the inductors 1 to 5 For example, there is a percentage loss distribution of: OB 31.3%, ground 45.5% and UB 23.2%.
• b: When all inductors are energized at the same time, OB 24.2%, ground source 62.8% and UB 13.0%.

The latter means that most of the heating power then deposited in the earthworks, if a simultaneous Current supply of the inductors takes place, with a phase shift of φ = 180 ° between adjacent inductors. Therefore, a switch between the types of lighting depending on the timing of the warming of Erdbodenstätte be advantageous, in particular depending on the desired heating power distribution of the generators or the number of generators used.

Overall, it can be stated that the relevant for the heating of the ground floor electrical parameters are given temporally and / or locally variable and can be changed from outside the ground to optimize the heating. In the associated device, at least one generator is present, but preferably a plurality of generators, wherein its / their electrical parameters such as current (I), frequency (f _i ) and / or phase (φ) are variable and optionally operationally variable.

above was a method for heating soil with soil, which is electrically heated, described, wherein an inductive heating method is applied, in which the soil by high-frequency electromagnetic Fields in the range between 10 and 200 kHz is heated.

at an associated installation for carrying out the Method has a generator for high frequency predetermined Frequency in the kHz range, to the at least one inductor with a Hinleiter and a return conductor is connected. The high frequency generator is either a series resonant converter or a parallel resonant converter, and the inductors are preferably made of multifilament leads. Use finds the method or such a plant in the context active environmental protection for the reclamation of contaminated premises.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - DE 102007040605 [0015]
• - DE 102008044953 [0020]
• - DE 102008044955 [0021]

Cited non-patent literature

• - THERIS method (Hiester et al., Scientific Report No. VEG 05, Institute of Hydraulic Engineering, University of Stuttgart, 2003, No. 2003/14 [0006]
• - http: //.bwplus.fzk.de/index_Projekte_datenbank.html [0006]
• - Habilitation Thesis H. Roland, Th. Bergakademie Freiberg 2006 [0006]

Claims (24)

A method for heating soil with soil, which is electrically heated, characterized in that an inductive heating method is used, wherein the soil is heated by high-frequency electromagnetic fields in the range between 10 and 200 kHz. Method according to claim 1, characterized in that that a soil with a through organic matter, in particular Hydrocarbon compounds, contaminated soil is heated. A method according to claim 1 or claim 2, characterized characterized in that for heating the soil by the high-frequency electromagnetic fields resulting eddy currents be used. Method according to claim 3, characterized that for generating the eddy currents current-carrying Ladder whose distance can be specified can be used. Method according to claim 4, characterized in that that the distance of the current-carrying conductors as inductors partially specified in different areas. Method according to claim 5, characterized in that that an array of current-carrying conductors is used. Method according to one of the preceding claims, characterized in that in the soil sections of energy between 1 and 100 kW per meter length of the current-carrying Ladder will be introduced. Method according to one of the preceding claims, characterized in that the soil conductivity distribution is considered in the soil. Method according to claim 8, characterized in that that the soil conductivity distribution is influenced, preferably by introducing a conductive solution in the soil. Method according to one of the preceding claims, characterized in that the soil in succession heated to different temperatures and for a predetermined time interval kept at the respective temperature becomes. Plant for carrying out the method according to claim 1 or one of claims 2 to 10, with a generator ( 60 ) for the radio frequency predetermined value (f _i ) in the kHz range, to the at least one inductor arrangement ( 10 ) from a leader ( 15 ) and a return conductor ( 20 ) connected. Plant according to claim 11, characterized in that the high-frequency generator ( 60 ) is a series resonant converter. Plant according to claim 11, characterized in that the high-frequency generator ( 60 ) is a parallel resonant converter. Plant according to claim 12 or claim 13, characterized in that the high-frequency generator ( 60 ) Has variable frequency outputs (f _i ) connected separately to the return conductor ( 15 . 20 ) of the inductor arrangement ( 10 ) are connectable. Plant according to claim 11, characterized in that at the inductor ( 10 . 15 . 20 ) several leads connected in parallel ( 11 - 14 ) and a plurality of return conductors ( 16 - 19 ) are separately controllable and form an array. Plant according to claim 15, characterized in that a control device ( 62 ) for the variable connection of the forward and return conductors ( 11 - 14 . 16 - 19 ) is available. Plant according to Claim 11, characterized in that 15 ) and return conductors ( 20 ) of the inductor arrangement ( 10 ) in the area to be heated ( 100 ) Have a defined distance (a _i ), which determines the heating power. Plant according to claim 11, characterized in that the lead conductor ( 15 ) and the return conductor ( 20 ) have regions of different distances (a _i ). Plant according to claim 11, characterized in that the inductor arrangement ( 10 ) with forward ( 15 ) and the return conductor ( 20 ) form a compensated multifilament conductor. Plant according to claim 19, characterized that the multifilament conductor by means of integrated, electrically in Series switched capacities is capacitively compensated. Use of a plant according to claim 11 or a of claims 12 to 20, wherein the plant with a method operated according to claim 1 or one of claims 2 to 10 is responsible for tasks within the framework of active environmental protection. Use according to claim 21 for the decontamination of the soil in undeveloped areas, such as abandoned military training areas, landfills od. Like., The previous bestimmungsge may have come into contact with hydrocarbon-based contaminants. Use according to claim 21 for decontamination of the soil in built-up areas, whereby the procedure under existing Structures over essentially horizontally guided Drilling is carried out Use according to claim 23 at filling stations, the during the previous intended operation with Hydrocarbon-based contaminants, such as engine oil od. Like., Have come into connection.