modeling of the nonlinear physical processes 3rmebrk.kz/journals/3714/32157.pdf · 2017. 9. 29. ·...
TRANSCRIPT
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Modeling Of The Nonlinear Physical Processes 3
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4 ISSN 1811-1165. Eurasian Physical Technical Journal, 2012, Vol.9, No.2(18)
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Modeling Of The Nonlinear Physical Processes 5
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Modeling Of The Nonlinear Physical Processes 3
UDC 517.957, 622.833.5
SIMULATION OF ROOF CAVING IN WHILE CONDUCTING EXCAVATION
MINING WORK
P.V. Makarov, E.P. Evtushenko, N.A. Bektemirov
Institute of Strength Physics and Materials Science of Siberian Branch Russian Academy of Sciences (ISPMS SB RAS)
2/4, pr. Akademicheskii, Tomsk, 634021, Russia, Phone: +7 (3822) 286875, e-mail: [email protected]
Peculiarities of geo-environment evolution as a nonlinear dynamic system with the self-organized
limiting feature are discussed. Calculations of the initial and subsequent roof cavings for different advancing
rates were fulfilled. Special attention was given to the study of unsteady nonequilibrium deformation process
in the roof at high face advancing rate. It is shown that other features of such systems are the existence of
calm zones in the area of looming crisis and peculiarities of slow dynamics of deformed systems can be sure
portents of the fact that the process of destruction epicenter formation is moving to become a superfast
catastrophic evolution stage.
Keywords: simulation, roof caving, rate, destruction, distribution.
Traditional criteria approach of phenomenological macroscopic mechanics is not capable in
principle to solve the problem of destruction prognosis, as it is based on macroscopic scale of
averaged description, while all solid objects and types of geo-medium are multi-scale systems. The
Evolution concept of destruction foundation [1] is an idea of hierarchical and multi-scale nature of
deformation process – basic ideas of Physical Mesomechanics and Nonlinear Dynamics [1-4].
Nonlinear Dynamics sheds a new light onto a problem of prognosis too, even when it "deprived us
of an illusion of a global predictability: we cannot forecast, starting from some horizon of
prognosis, the behavior of simple enough systems" [3]. Thus not so simple a question arises: what is
the horizon of prognosis for the process of destruction of a medium with a given rheology? Or in
other words: starting from which stage or scale can we answer the question, where and when will
the slow quasi-stationary phase of the heart of destruction formation come up to escalation at the
studied macroscopic scale?
We see a significant progress in the area of catastrophic events prediction, which includes the
problem of destruction. This progress is connected to a new concept of self-organized criticality of
nonlinear dynamic systems [5, 6], which contradicts seriously with traditional thinking, based on
which rare catastrophic phenomena were deemed accidental independent events, where the future is
not practically impacted by the past. Such approach leads to Gaussian statistics - normal Gaussian
distribution of probability for an independent accidental event.
The statistics of natural disasters – earthquakes, hurricanes, floods, technogenic catastrophes:
the destruction of different constructions, industrial explosions, as well as many other disasters -
crash at the stock-markets, information leaks, etc., as a rule, is subject to power law probability
distribution [3, 7].
Power law distribution is a fundamental property of evolution of the majority of multi-scale
hierarchical nonlinear systems, and in the event of loaded media it reflects their following most
important qualities: 1) formation of long space and time correlations in the evolving system, that
scope all hierarchy of scale; 2) self-similarity of destruction processes, stipulated by self-similar
character of accumulating the defects and damages in all hierarchy of scale; 3) migration of
deforming activity in a formed area of space and time correlation.
The other most important side of such nonlinear systems is the existence of slow dynamics
within, that is a dynamic correlated process, significantly slower than fast information exchange in a
dynamic system. In deforming solid objects and media the processes of locating deformation and
damage, forming of the deformation fronts of different scale, epicenters and different waves of
mailto:[email protected]
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4 ISSN 1811-1165. Eurasian Physical Technical Journal, 2012, Vol.9, No.2(18)
damage constitute the slow dynamics of nonlinear system in the process of deformation. And
information in these systems is transmitted via tension (voltage) waves distributed with the speed of
sound that exceeds the typical speed of slow dynamic processes by a lot [8].
Systems with such properties are called the systems with self-organized criticality [5, 6]. In
such systems any event, because long cause and effect relations appear, – will inevitably call the
next event, etc., provoking the avalanche of events, touching upon all hierarchy of scale, i.e. all
system as a whole. In other words, the fundamental property of the systems with self-organized
criticality is the fact that they evolve (speed) to critical condition by themselves [3]. Consequently,
the main danger of "power" catastrophes is not only in the fact that its probability is much higher,
than in Gaussian system, and it cannot be disregarded, but in the fact that the catastrophe in the
system with self-organized criticality is inevitable. Indeed, if the process of destruction is correlated
statistically in all hierarchy of scale up to the macroscopic scale of a sample, then it will inevitably
reach that macroscopic scale. This process is governed by nonlinear character of properties of a
dynamic system as a whole, which follows from nonlinear character of evolution of tense and
deforming condition (nonlinear equation of deformed solid objects' mechanics), nonlinear character
of rheology (nonlinear state of definitive equations, including kinetic equations of aggregating non-
elastic deformations and damages in a different scale and a nonlinear state of media durability
properties' degradation), nonlinear quality of positive and negative feedback. Consequently, in
critically self-organized systems one cannot single out statistically independent mesoscopic scales.
At this moment it is considered proven that deformed solid objects are truly dynamic nonlinear
systems showing properties of self-organized criticality. For geo-media, the widely known
Gutenberg-Richter and Omori laws reflect the relevant statistics of seismic events. Analysis of
destruction processes of laboratory samples [9], as well as of constructions [10] by the acoustic
emission method leads to the same universal dependence - Gutenberg-Richter and Omori laws.
A predictive model, - capable of describing the mechanism of forming the epicenter of the
future destruction, and, importantly, of predicting when and under what conditions the slow quasi-
stationary phase of evolution will turn into the superfast catastrophic regime, - can be only the
model that accounts for all most important properties of the loaded nonlinear media's evolution
process, including the characteristic properties of self-organized criticality. In ISPMS SB RAS the
evolutionary approach to modeling of solid objects and media's destruction is being developed [1,
2]. This approach describes the processes of self-organizing in the loaded geo-medium, locating
non-elastic deformations and damages in it, forming of block hierarchy; allows to model the slow
stages of evolution at any time, including geological, as well as the superfast catastrophic regimes
of evolution, - so-called acute regimes.
The proposed evolutionary concept of describing the deformation feedback to the loading of
solid objects is based on the ideas of nonlinear dynamics and dynamic equations of solid objects'
deforming mechanics. Such approach describes the destruction of solid objects and media (elastic
and brittle) as common mutual growth process of non-elastic (plastic) deformation, related damage,
degradation of medium durability, and, finally, macroscopic destruction, which happen upon a
catastrophic decline of local durability to zero. Therefore, numerical solutions demonstrate the
fundamental property of all evolutionary processes - the existence of two stages: 1) quasi-stationary
stage of relatively slow accumulation of changes in a nonlinear system; 2) catastrophic superfast
stage of evolution, when the events develop in an acute regime.
Based on the discussed model [1, 2] the calculations of a loaded and deformed condition of a
massif evolution over the mine in the field of gravity forces were carried out. The model takes into
account the internal friction, dilatancy, and accumulation of damages and degradation of geo-
medium's durability characteristics. The developed method of calculations allows solving practical
problems of mining stability under the timing factor more accurately and correctly. The developed
models of a damaged massif allow modeling the processes of damage accumulating and developing
of cracks of different sizes, as well as catastrophic collapse of rock.
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Modeling Of The Nonlinear Physical Processes 5
Attention of this work is focused on the research of the three following important problems:
specifics and mechanism of forming the destruction centers in brittle and quasi-brittle media, study
of the destruction transition process from a slow quasi-stationary phase to a superfast catastrophic
regime, evaluation of risks, and a prospect of prognosis of possible catastrophic destruction of
massif elements with mining. Numerical solution is carried out in two-dimensional dynamic stage
for the condition of plain strain.
Equations system, solution method and detailed formulation of the problem were published
earlier [11]. The proposed approach allows describing the stages of slow preparatory phase of stress
strain state evolution, forming of destruction stages and superfast acute regime. Relevant times and
scale of these evolution stages are determined by nonlinear qualities of geo-medium on the relevant
scale. Thus in high speed of mining we have lengthy sections of hanging roof, so a nonequilibrium
destruction regime takes place. It is also shown that depending on the competition of negative
feedback, stabilizing the deformation process and evening out of inhomogeneous pieces in
parameter distribution, and positive feedback, caused by the degradation of loaded medium, the
scenario of medium evolution can change from a typical viscoplastic course to a brittle behavior.
Fig. 1 shows the results of the calculation of roof rock deformation at the moment when the
excavation reached 50 meters in length (calculation and excavation can continue). Different values
of damage accumulation parameters were chosen, which allowed the possibility to describe the
behavior of the geo-medium either as viscid (Fig. 1.a), or as brittle (Fig. 1.b), depending on the
medium property, as well as the specifics of loading.
a) b)
Fig. 1. The character of damage development in a massif over excavation (black horizontal line).
Grey shading shows average tension, thin lines - lines of nonelastic skidding (a), main cracks (b).
16 20 24 28
0,000000
0,000002
0,000004
0,000006
0,000008
0,000010
0,000012
ddt
t, дни
16 20 24 28
0,000000
0,000005
0,000010
0,000015
0,000020
t, дни
ddt
a) b)
Fig.2. The graph of nonelastic deformation speed in the roof monitoring.
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6 ISSN 1811-1165. Eurasian Physical Technical Journal, 2012, Vol.9, No.2(18)
The built graphs of monitoring the speed of nonelastic deformation (damage) in the chosen
points of the roof are shown in Fig. 2. One can see that in a case of a viscid feedback of a medium
(Fig. 2.a) nonelastic course in the roof is developing in waves, at the rate as excavation continues,
and creates even bigger tension and deformation in the caving roof. Roof caving in brittle geo-
medium (Fig. 2.b) is developing as a sequence of periodic catastrophes (extension of a main crack),
at the rate of continuing excavation; the period here is related to the character of excavation
movement and geo-medium properties, in part to the speed of accumulating damages in it.
Therefore, the obligatory stage of a geo-medium evolution is reflected in the model: the catastrophe
at the relevant scale. Physically, this regime means the burst of destruction from a minor scale to a
larger one, the increase of the destruction scale is always developing in the acute regime.
Fig. 3 shows the nature of growth of damage function D (0D1) for a main crack in the roof
over an excavated space (medium viscid-brittle). One can see that on Day 28 the slow quasi-
stationary phase of damage evolution D is replaced by a catastrophic regime (Fig. 3a).
Consequently, the yield strength degradation speed is also transformed into an acute regime (yield
strength Y=Y0(1–D), where D1,Y0) and, as a result, the roof collapse happens.
Fig. 3. The character of damage function growth in the roof.
The fundamental property of evolution is the existence of calm zones before a catastrophe.
This phenomenon is demonstrated in Fig. 3b. In numeric calculation of a problem of roof
collapsing, the damage accumulation speed monitoring in the nearest zone of a future catastrophic
event was executed. The processes of damage accumulation for accompanying cracks forming in
this area stopped still (curves 2, 3, 4 on Fig. 3b), and the accumulation of damage in the future main
break has peaked sharply (curve 1 on Fig. 3b).
Therefore, any macroscopic destruction is an obligatory catastrophic stage of a geo-medium
evolution - an acute regime at the relevant scale. Physically this regime means the plunge of
destruction from a minor scale to a larger one. Consequently, the increase of destruction scale is
always developing as a catastrophe in the acute regime, and all the processes of damage
accumulation and medium degradation in the area of preparation to a multi-scale event are stopping
still.
The developed method of calculations allows describing the first and subsequent roof cavings
for modern conditions of increasing pace of excavation movement and a non-equilibrium condition
of the rock in the bared roof.
4 8 12 16 20 24 28 t, дни
D
0
0.5
1
a
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Modeling Of The Nonlinear Physical Processes 7
a)
b)
c)
d) e)
f)
Fig. 4. The modeling of a first (a,b,c) and secondary (d,e,f) roof collapses for different speeds of excavation
pace: 2m/24hrs (a,d), 4m/24hrs (b,e), 8m/24hrs (c,f). The accumulated damage of a geo-medium in conditional values
from 0 to 1 is reflected.
Fig.4 shows the results of roof caving modeling for different speeds of extending the
excavation shaft. For primary caving in the border conditions the model approximation for the roof
was used in the form of a beam created in the process of excavation, for the secondary one -
consoles (cantilevers). For slow speed of excavation, a larger damage accumulation in the roof geo-
medium is typical, and therefore, more viscid (lengthier in time) character of roof caving. This work
was supported by grant RFBR № 12-05-00503-а.
REFERENCES
1. Mathematical theory of evolution of loaded solids and media // Phys. Mesomech. – 2008. – V. 11, No. 5-6. -
213 p.
2. Makarov P.V. Evolutionary nature of structure formation in lithospheric material: universal principle for fractality of solids // Russian Geology and Geophysics. – 2007. V. 48, No. 7. - 558 p.
3. Akhromeeva T.S., Kurdyumov S.P., Malinetskiy G.G., Samarskiy A.A. Structures and Chaos in Nonlinear Media. – 2007. Fizmatlit, Moscow (in Russian).
4. Malinetskiy G.G., Potapov A.B. Modern Problems of Nonlinear Dynamics. - URSS, Moscow. - 2002 (in Russian).
5. Ananthakrishna G., Naronha S.J., Fressengeas C. and Kubin L.P. Crossover from chaotic to self-organized critical dynamic in jerky flow of single crystals // Phys. Rev. E. – 1999. – V. 60, No. 3. – P. 5455-5462.
6. Bramwell S., Holdsworth P., Pinton J.-F. Universality of rare fluctuations in turbulence and critical phenomena // Nature. – 1998. – V. 396. – P. 552-554.
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8 ISSN 1811-1165. Eurasian Physical Technical Journal, 2012, Vol.9, No.2(18)
7. Pisarenko V.F., Rodkin M.V. Heavy-tailed distributions: application to the analysis of accidents // Vichislitelnaja seismologija. – 2007. - V. 38. (in Russian).
8. Goldin S.V., Yushin V.I., Ruzich V.V., Smekalkin O.P. Slow motion - a myth or reality // Fizicheskie osnovy prognozirovanija razrushenija gornyh porod.- Krasnoyarsk. - 2002. (in Russian).
9. Panteleev I.A., Froustey C., Naimark O.B. Structural-scaling transitions and universality of statistics of fluctuations in metal plastic flow // Vychislitel'naja mehanika sploshnyh sred. – 2009. – V. 2. – № 3. (in Russian).
10. Prediction of cracking evolution in full scale structures by the b-value analysis and Yule statistics // Phys. Mesomech. – 2008. - V. 11, No. 5-6. – 260p.
11. Makarov P.V., Smolin I.Yu., Evtushenko E.P., Trubitsyn A.A., Trubitsyna N.V., Voroshilov S.P. Evolution scenarios of the rock mass over the opening // Fiz. Mezomekh. 2009. – V. 12, No. 1. - 65 p. (in Russian).
Article accepted for publication 07.08.2012
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Heat Physics, Hydrodynamics, Energetic 9
UDC 53.097
THE INFLUENCE OF UNDERWATER SPARK DISCHARGE ON THE STRUCTURE OF
SHUBARKUL COAL
K.Kussaiynov, M.S.Duisenbayeva, G.K.Alpysova, E.T.Tanashev, A.Tolynbekov
Karaganda State University named after E.A. Buketov, 100026, Kazakhstan, Karaganda, Universitetskaya Str.28
Nowadays petroleum is the main source of organic raw materials. Its limited world reserves and
permanent increase in the cost of production due to involvement in exploitation more hard-to-reach fields
stimulates the development of new technologies for chemical processing of alternative organic raw
materials. Coal, world reserves of which are substantially larger than those of oil and gas, is considered in
the future as one of the basic raw materials for the production of motor fuels and organic synthesis products.
In this paper we propose to process Shubarkul coal using electric hydro-pulse technology. Application of
electric hydraulic technique brings substantial economic benefits and contributes to significantly reduce
harmful emissions into the environment or recycle harmful waste products. Study of influence of electric
hydraulic effects on heterogeneous media due to rising costs for energy and mineral resources, the
deterioration of the environmental situation is currently necessary and urgent.
Keywords: electric hydro-pulse plant, electric-hydraulic effect, shubarkul coal, coal-water fuel, electric discharge.
Kazakhstan has huge deposits of brown and hard coal of various metamorphism stages, which
are widely used mainly for production of coke used in the steel industry, and for energy purposes.
But these reserves of coal are not effectively used at present. So for the scientists, the age of
technological progress poses the problem of development of optimal processing technology and use
of coal. One of the efficient techniques of coal utilization is the process of obtaining motor and
boiler liquid fuels, energy and process gases, semi-synthetic resins, soil conditioners etc., from coal
[1]
Coal-water fuel (CWF) is a mixture (slurry) of finely ground coal and water. In some cases, the
suspension may include various additives (surfactants, stabilizers, etc.) that change the stability,
viscosity and other properties of the CWF. CWF can be used as a substitute for fuel oil, gas and
coal. The main advantages of CWF are reduction in fuel costs compared to those of fuel oil and gas,
as well as lower harmful emissions, particularly NOx and the technological ease-of-use of coal in a
liquid form. We propose a coal processing technology by using the electric hydro-pulse technique.
It is possible to grind coal to a certain fraction by means of an electric discharge in a fluid. [2.3]
The essence of this method is that inside a volume of liquid held in an open or closed vessel, a
specially formed electric pulse discharge of a certain form (spark, brush, etc.) is implemented.
Around the field of its formation there is super-high hydraulic pressure capable to perform useful
mechanical work and accompanied by a set of physical and chemical phenomena [4].
In the Laboratory of physics of pulse phenomena in heterogeneous media of the Chair of
engineering thermal physics named after Prof. Zh.S. Akylbaev at E.A. Buketov Karaganda State
University an electro-hydraulic plant for coal processing was installed.
The electric hydro-pulse plant is designed in the form of structural aggregates consisting of a
pulse voltage generator, a triggered spark gap, a cell, an ignition block, a voltage divider, a current
shunt and a control panel.
The scheme of the electric hydro-pulse plant and its separate units are shown in Figure 1.
The experimental stand works as follows. After switching on the control panel a control
voltage is applied and the generator produces high-voltage pulses of specified energy which are
transferred to the electrode system of the working cell area with the object of study through the
triggered spark gap and high-voltage power lines. [5]
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10 ISSN 1811-1165. Eurasian Physical Technical Journal, 2012, Vol.9, No.2(18)
Fig.1. Block diagram of the electric hydro-pulse plant.
The working cell of the electro-hydraulic plant for coal processing was also installed in the
Laboratory of physics of pulse phenomena in heterogeneous media.
There are two measuring electrodes inside the cell, one of them is fixed and the other is
attached to the micrometer screw to adjust the distance between the electrodes. Figure 2 shows a
general view of the cell designed for grinding coal. [6]
Fig.2. The working cell designed for grinding: 1- working cell cover, 2 - electrode of positive polarity,
3 – metal rod of negative polarity.
In the experiments the optimal parameters of coal grinding at different electrical parameters of
electric hydro-pulse plant were determined.
2
1
3
ELECTRO-HYDRAULIC PLANT
PULSE VOLTAGE
GENERATOR
TRIGGERED
SPARK GAP
CELL WITH THE
OBJECT OF STUDY
IGNITION UNIT
VOLTAGE DIVIDER
CURRENT SHUNT
CONTROL UNIT AND TEST INSTRUMENTS
CONTROL PANEL DELAYED-PULSE
GENERATOR
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Heat Physics, Hydrodynamics, Energetic 11
In Figure 3 (a, b, c) dependency graphs of the degree of grinding on the inter-electrode distance
for different capacitance of the capacitors are shown. Coal processing time t = 3 minutes, the coal
fraction of diameter d = 8 mm, distance of the triggered spark gap ld = 7 mm.
In Figure 3 (a) for the size of coal fraction d = 8 mm the distance between electrodes varied ld
= 7, 8, 9, 10 mm. The graph shows that at the inter-electrode distance ld = 7 mm and the capacitance
of the capacitor C = 0.25 μF the number of fractions of the diameter df
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12 ISSN 1811-1165. Eurasian Physical Technical Journal, 2012, Vol.9, No.2(18)
1
3
5
7
7 8 9 10
c)
Fig.3. Dependency graphs of the degree of grinding on the inter-electrode
distance for the capacitance of capacitors C = 0.25 (a), 0.5 (b), 0.75 (c) μF.
In Figure 3 (b) at the inter-electrode distance ld = 7 mm and the capacitance of the capacitor C
= 0.5 µF the number of fractions of the diameter df
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Heat Physics, Hydrodynamics, Energetic 13
UDC 536.33
NONDESTRUCTIVE TESTING FOR DIAGNOSTICS OF PIPELINES
B.R. Nussupbekov, D. Zh. Karabekova, S.S. Zhargakova, A.Zh. Beisenbek,
Karaganda State University named after E.A.Buketov, 100026, Kazakhstan, Karaganda, Universitetskaya Str.28, [email protected]
Thermal methods of nondestructive testing are widely used for the analysis of the thermal
insulation of underground pipelines. In heat methadone nondestructive testing, the thermal
energy is distributed in the test object. Temperature field of the object's surface is a source of
information on the characteristics of heat transfer. This article describes the modifications we
have developed some of the heat flux sensors. A common element of these devices is the battery
thermoelectric sensor special design, acting as a thermoelectric converter heat flow.
Keywords: heat flux, heat flux sensors, thermal radiation detectors, heat sensor metric.
Thermal methods of nondestructive testing are widely used for different kinds of protective
coatings for the analysis of the thermal insulation of underground pipelines, in oil and gas industry,
house-building, etc.
Violation of thermal insulation leads to a change of temperature on the surface of the coating.
Conclusion about the state of thermal insulation can be made on the basis of data of the surface
temperature of insulation and temperature field inside the studied object [1].
One of the main structural units of the automatic system for the experimental investigation of
thermal processes is a unit for the measurement of thermal processes [2]. Requirements for complex
sensors, built the block, are defined by the basic parameters of the processes investigation. The
basis of the unit contents specially designed heat flux sensors, heat detectors, which allow
measurements of local and average parameters of thermal processes under stationary and non-
stationary conditions.
Among the various applications of the heat flux sensors the control of the state of thermal
insulation of pipes with coolants has a special place. Such control can be done by measurement of
heat losses with primary thermoelectric converter heat flow, heat detector and electronic unit for
conversion of signal. The main lack of these devices is the dependence of their data from accidental
changes of the environment.
To solve the problems, we have developed several versions of the heat flux sensors, whose
indications are independent from changes in the environment [2, 3]. A common element of these
devices is the special designed battery of thermoelectric sensors, acting as a thermoelectric
converter heat flow. Thermoelectric sensor is designed as a finite cylinder, whose one base is the
work surface, and the second one has the thermal contact with the body of environmental
temperature. Built-in heaters can create heat flow through a thermoelectric sensor in the direction
perpendicular to its bases [3].
In one of the versions of the thermal flow sensor "active" junctions of thermoelectric converter
are in thermal contact with the receiving plate, and "passive" junctions contact with a heating
element, the temperature of which is controlled by temperature-dependent element. This design
allows you to combine the function of two heat-flow units in one. During the preparation of the
device the receiving plate is put in thermal contact with the test object in the place with absence of
defects in thermal insulation. Electrical current is passed through the heating element and its value
must be such that the signal at the output of the thermoelectric converter would be constant. This
means that the heating element generate a reference heat flaw through a thermoelectric converter
that is equal in magnitude and opposite in direction to heat flow from the test object in the field of
thermal insulation defects. In the investigation of possible defects in insulation the current through
the heating element is not regulated. This leads to a change in the signal at the output of the
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14 ISSN 1811-1165. Eurasian Physical Technical Journal, 2012, Vol.9, No.2(18)
thermoelectric converter of the heat flow. The magnitude of the changing allows appreciate the
degree of thermal insulation defects.
In another variation of the heat flux sensor the heating element is replaced with thermoelectric
refrigerator, "cold" junctions are embedded in the radiator, and "hot" one is in thermal contact with
the thermoelectric converter of a heat flow. Through the thermoelectric refrigerator the electric
current is passed with a value which gives the zero as the output signal of the thermoelectric
converter if the receiving plate is in contact with the investigated object in the absence of defects in
the thermal insulation. Thus, the heat flux that produced by the thermoelectric cooler in the
direction of a thermoelectric converter is reference one. With these data the heat fluxes in areas
where in thermal insulation defects have places are compared.
In the third modification of the heat flux sensor the heating element serves as a receiving plate
simultaneously. This modification implies the calibration method of substitution of the heat flow
from the investigated object by one from a heating element under passing an electric current trough
it.
The proposed devices can operate as with a single channel scheme so with a dual channel one.
Detecting anomalously high values of energy losses indicate the section of a pipeline with fully or
partially damaged thermal insulation or mechanical damage of the pipe material.
The aim of the investigation is to study the heat sensor operating for diagnostics of pipelines.
The main element of this heat sensor is the laminated sensitive element of battery type (Figure 1).
Heat flow through the protective film 1 goes to the sensor 2. The hot junctions of the thermal
batteries have thermal contact with a protective film and the cold junctions with thermal stabilizer 3.
In this case, the role of thermal stabilizer performs massive body transferred the heat flow through
the bottom of the housing 4 to the radiator 5. To eliminate the heat transfer from the flank surface
the sensor element is surrounded by a heat insulator 6. The entire system is closed with a conical
lateral surface 7.
Fig. 1. Schema of the heat sensor: 1 – protective film, 2 – sensor, 3 - thermal stabilizer, 4 - bottom of the body,
5 – radiator, 6 - heat insulator, 7 – flank surface, 8 - gauge coils.
As a model of a sensor element, let‟s consider homogeneous limited cylinder.
Let the function q (r, t) describes the dependence of the heat flux, directed on a base of the
cylinder, from the radius r and time t. The function ),,( tzrqv describes the dependence of the
power of internal sources (W/m2) from the radius r, the height z and time t. The heat exchange has
place between all the surface of the cylinder and the environment variable temperature Tc(r,z,t) due
to the Newton's law [4].
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Heat Physics, Hydrodynamics, Energetic 15
Fig.2. Schema of a sensor element.
The heat equation and boundary conditions in this case for a cylinder with radius R and height
1 will be next:
),,(),,(),,(1),,(1 2 tzrq
z
tzrT
T
tzrT
rrT
tzrT
a
v
(1)
zrflzrT ,,, (2)
tzRTtzRT
z
tzRTcR ,,),,(
,,
(3)
tlrTtlrTz
tlrTcl ,,,,
,,
(4)
torTtorTz
torTc ,,,,
,,0
(5)
where T*c(r,o,t) - the equivalent temperature of the environment:
0
,,,,,
trqtorTtorT cc
(6)
10,, R are the coefficients of heat transfer from the environment to the lateral surface of the
cylinder with the z = 0 and z = 1, respectively.
To solve the boundary problem (1) - (5) we will use the method of finite integral Hankel
transformations with respect to r:
rtzrTR
rrJtzT n
R
l
Ln
,,,, , (7)
where
R
rJ nl is the Bessel function of a zero order, μn are roots of the equation:
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16 ISSN 1811-1165. Eurasian Physical Technical Journal, 2012, Vol.9, No.2(18)
R
l
Bi
d
J
J
)(
)(
1
(8)
in which /RBi RR .
Then let‟s apply the finite neutral transformation of the general form o to the variable z:
dzzbKtzTtbu knkn ,,,,1
0
, (9)
where K (bk, z) is the core of the transformation. Let‟s put
zl
b
b
Biz
l
bzbK k
k
lkk sincos, , (10)
where Bil=α11/λ.
It is easy to show that the coefficients must satisfy the next equation:
0
0
2
BiBib
BiBibctgb
Lk
LkR
, (11)
where Bi0=α01/λ.
Inversion formulas for finite integral transformations (7) and (9) are, respectively:
1
1
0
2 ),(
,,),,(
kk
kknn
dzzbK
zbKtbutzT
, (12)
)(
,,2
),,(222
12
nlnR
nln
n
nJBi
R
rJ
tzTR
tzrT
. (13)
Making the transition from the image to the original formulas (12) and (13) we obtain the
desired expression
nlnR
knln
n
k
n JBi
zbKR
rJ
cR
tzrT
221 1
2
),()(4
),,(
l R
nlkn
R
rJzrft
l
b
Ra
0 0
2
2
2
2
,,exp
×
t
l
b
Ra
adrdzzbK kn
t
k 2
2
2
2
0
exp,
R
nlcb drR
rrJ
a
rqtorTKa
k
0 1
0,0
1
,,,
+
+
1
00
)(,,, nlRnl
R
Ckl RJdrR
rrJtlrTlbK
R
kvnc ddzzbKdrtzrqR
rrJtzRT
0
1 ),()),,()(),,( , (14)
where
-
Heat Physics, Hydrodynamics, Energetic 17
k
ik
k
k
k
l
k b
BiBib
b
b
b
Bi
с
1222
sin22
sin11
1
. (15)
The solution (14) describes the temperature distribution in a limited solid cylinder with the
boundary conditions (2) - (5). Let‟s consider the special case solutions. Let
constTozrT c ),,( ,
cTtzrTtzr ),,(),,( ,
if the surface density of the absorbed radiation flux and internal sources of power q (r, z, t)
depend on time, they can be represented as:
tFqtq 0 )()( tFqtq vov
The expression for the excess temperature can be written as follows:
12
0
22
2
12
.4
,,k
nnR
nnk
т JBi
R
rJc
lR
dtzr
t
knk
n
k tl
b
Rd
l
zb
B
Bi
l
zb
02
2
2
2
0 expsincos
R l
n
R
lvnk
k
k drR
rrJFqdr
R
rrJ
l
zb
b
Bi
l
zbtFq
0 0 0
000
0 sincos)(
ddzl
zb
B
Bi
l
zb k
k
k
sincos 0
Consider the case of internal and external heating. When q(t) = 0, i.e. when internal (by
current) heating has place, the temperature field of the cylinder is described by:
1 1
22
0
0
04,,n k nRnk
nRk
BiJb
R
rJBic
cp
qvtzr
)(sincos2
sin2
sin 20 tPl
zb
b
Bi
l
zbb
b
Bib k
k
kk
k
k
,
where
dtl
b
RdFtP
t
kn
0
2
2
2
2
exp)()( .
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18 ISSN 1811-1165. Eurasian Physical Technical Journal, 2012, Vol.9, No.2(18)
When the external heating (radiation) has place, that is 0)( tqv , the excess temperature is
given by:
1 1
22
0
04
,,n k nRnk
nkk
BiJb
R
rJBic
lcp
qtzr
kik bBib sincos )(sincos0 tP
l
zb
b
Bi
l
zb k
k
k
.
Thus, the approach proposed in this paper has allowed to consider the temperature field of the
device sensor described here in the different cases of heating. This device can be used in the sensor
unit under automated experimental research of some particular processes.
For the purpose of testing of the method in the laboratory conditions the temperature field of
wooden shield with sizes 1500x2000x20 mm, heated by radiation from the opposite side of the
muffle furnace (t = 4000C), located from the shield at a distances of 2 m and 4 m. On the shield was
applied the grid with the step of 200 mm. The measurements were carried out at the nodes. The
dependence of the relative radiometer signal (the ratio of the current signal to the maximum one) in
respect to the coordinates of the grid is shown in Fig 3.
Fig.3. Dependence of relative signal of heat sensor on the coordinates.
On the horizontal axis are number of points from left to right. The numbers on the curves
correspond to the number of horizontal lines from the top to the bottom of the shield. The
measurements confirm the potential possibility to use the proposed heat sensor for realization of the
nondestructive heat control method.
REFERENCES
1. Antipov Y.N. Measurement of pulsed light. – Karaganda, 1981. – 94 p.
2. AS 27617 RK 1999. A device for measuring heat flow. Antipov Y.N, Karabekova D.Zh.
3. AS 37716 RK 2001. A device for measuring heat flow. Kussaiynov K. Gladkov V.E., Karabekova D.Zh.
4. Antipov Y.N., Karabekova D.Zh., Akhtanova M.K., Imanasova N.V. Instruments for measuring the energy
performance of thermal processes KSTU news Kaliningrad. - 2005.- № 7. p.241-245.
Article accepted for publication 5.08.2012
-
Heat Physics, Hydrodynamics, Energetic 19
UDC 621.7
ELECTRO-PULSE TECHNOLOGY OF PRODUCTION HEAT EXCHANGERS
FOR EXTRACTING THE HEAT FROM THE GROUND AT SHALLOW DEPTHS
K.Kussaiynov, S.E.Sakipova, K.M.Turdybekov, B.A.Ahmadiev, N.N.Shuyushbaeva, J.A.Kuzhuhanova
Karaganda State University named after E.A.Buketov, Universitetskaia Str. 28, Karaganda, 100026, Kazakhstan,
The aim of the study is to develop scientific and practical bases of introducing energy-saving heat pump
technology to heat and cold supply of residential, public and industrial premises on the basis of alternative
and renewable energy sources. The heat exchanger of the heat pump is installed in the wells for groundwater
heat. A widely used method of getting well, canals - drilling. Electro drilling, in which electrical energy is
directly in the slaughter goes into mechanical work, breaking the rock, is a fundamentally new way of
drilling. For its implementation are electro drills of various types and modifications.
Keywords: electric pulse technology, heat pump, heat exchanger, drilling, heat from the ground at shallow depths.
Currently, search and active use of new alternative energy sources in many developed countries
of the world are accepted as vital, strategic resources necessary to ensure the future development of
their economies.
Modern development of power engineering in the Republic of Kazakhstan is characterized by a
cardinal restructuring of the fuel and energy complex. This is due to the increase in the price of
fossil fuel in the world market, the aggravation of environmental problems.
In these circumstances, the measures to save fuel and energy resources are a priority in the
long-term energy policy.
In the CIS countries, large heat and power plants and district heating stations with a heating
capacity of more than 50 Gcal/h are the sources of district heating for residential, public municipal
buildings and public utilities. One of the energy saving alternatives is to obtain thermal energy
using a heat pump, which makes it possible to use heat of the ground, underground water, water
bodies, natural water flows, etc. [1]
For a small heat pump with a capacity of about 10 kW, which can be used for individual
houses, the expense of an underground water flow of about 1-2 m3/h is required. For this purpose a
heat exchanger is used. Heat exchangers can be arranged horizontally or vertically [2].
A horizontal ground heat exchanger is usually arranged near the house at a shallow depth. The
use of horizontal ground heat exchangers is limited by the size of available sites.
Vertical ground heat exchangers permit the use of low-potential heat energy of the ground
mass lying below the "neutral zone" (10-20 m from the ground level). Vertical ground heat
exchanger systems do not require large area sites and do not depend on the intensity of solar
radiation incident on a surface. Vertical ground heat exchanger works effectively in virtually all
types of geological environments, except for ground with low thermal conductivity, such as dry
sand or dry gravel. Systems with vertical ground heat exchangers are widely spread.
Vertical ground heat exchanger systems can be used for heat and cold supply of buildings of
different sizes. For a small building just one heat exchanger is enough; large buildings may require
an entire unit of wells with vertical heat exchangers.
Coaxial vertical ground heat exchangers located outside the perimeter of the building are the
main heat exchanger element in the collecting system of low potential heat of the ground.
These heat exchangers are 8 wells with the depth from 32 to 35 meters each, arranged near the
house. [3]
mailto:[email protected]
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20 ISSN 1811-1165. Eurasian Physical Technical Journal, 2012, Vol.9, No.2(18)
To use the groundwater heat, the heat exchanger of the heat pump is installed in the wells. A
widely used method to make wells and canals is drilling. Nowadays there are many types of drilling
rigs widely used in Kazakhstan. The existing technologies for drilling wells of heat exchangers are
efficient in case of soft ground in the absence of hard rocks and stone plates. Drilling a well with the
diameter up to half a meter to the depth of 25 meters in the condition of the above mentioned
constraints can be difficult. The proposed technology would make it easy to overcome such
obstacles, destroying them by the impact of shock waves at high-voltage discharge in water. It
involves crushing and grinding of hard rock that allows efficient drilling wells to the required depth
in the short term.
The main advantages of this technology are: the uniqueness of the proposed innovative way of
drilling hard rocks is the ability to work within limited space (covered premises, cellars, etc.), that
is, in many cases, impossible with traditional mechanical methods of drilling hard formations due to
the bulkiness of the equipment used.
The electrohydraulic drilling when the electrical energy turns into mechanical work directly in
the bottom, thus destroying the rock, it is a fundamentally new way of drilling. For its
implementation various types and modifications of electro-hydraulic drills are designed.
Depending on the design and purpose of a drill, it may have two or more electrodes, they can
be fixed, rotating and perform vibration movement. The movement of the electrodes can be caused
either by an external source (an engine), or due to the energy of flowing water, or action force of the
electro-hydraulic shocks.
Suggested electro-hydraulic drills constructively are divided into four main groups.
First group: electro-hydraulic drills with a rotating central electrode – it is experimentally
proved that the drills of the continuous face of this type at a voltage of 70-100 kW and capacity 0,7-
1.0 mF can drill large wells with the diameter of up to 450-500mm. The rotation of the front edge of
the central electrode is carried out in various ways (for example, by an electric engine, turbine,
driven by drill water supported through the drill pipe, as well as by reaction of electro-hydraulic
shocks) [4]
Second group: electro-hydraulic drills with fixed central electrode. In the course of
investigation on the creation of a drill with a fixed central electrode dependence of breakdown
voltage in a liquid on the mass content of any mechanical impurities in it was revealed. The method
of the so-called "dirty face" was suggested, and drill of continuous face used for this technique was
created as well.
The third group: linear drills. If, figuratively speaking, we "flatten" the continuous or circular
face drill with a fixed central electrode, we will constructively obtain two types of linear drills.
Linear drills with water supply through the central electrode with a length of cut equal to 1-2 m, at a
voltage of 50-80 kV can form narrow slits and slots with the widths of up to 8-10 mm not only
along direct, but also any curved lines.
Fourth group: drills of this type can drill all the rocks, frozen ground, ice, salt; they can cut
wood, perform various underwater works - cut expansion gaps in concrete channels, holes for the
groove at the bottom of dams and drill wells with any longitudinal curvature that is achieved by
imparting the corresponding longitudinal curvature to the drill rod.
But they all are not brought to the industrial applications, only their principles are described.
All aforesaid made it necessary to carry out experiments to develop an electro-hydraulic
technology of preparation of ground ditches for industrial use. For this purpose we used an
experimental setup based on the electro-hydraulic effect.
Electro-hydraulic effect - is a transformation of the process of hydrodynamic vortex power to
mechanical energy. Electro-hydraulic effect is a high voltage electrical discharge in a liquid
medium. During the formation of an electric discharge in a liquid energy release occurs within a
relatively short period of time. A powerful high-voltage electric pulse with a steep leading front
causes a variety of physical phenomena. Such as the emergence of ultra-high hydraulic pulse
-
Heat Physics, Hydrodynamics, Energetic 21
pressure, electromagnetic radiation in a wide range of frequencies up, under certain conditions, to x-
rays, the cavitations phenomenon. The electro-hydraulic discharge occurs upon the application of
pulse voltage of sufficient amplitude and duration to a liquid, resulting in evolving of an electric
breakdown [5].
To form the pulse with a short leading front voltage applied to the discharge gap in the liquid
we used the discharge gap in a gas – a gas discharger, and in order to generate certain pulse energy
an accumulating electrical capacitor was used. Once we developed and implemented into practice a
scheme of constructing electro-hydraulic setup, figure 1.
Fig.1. Scheme of electrohydraulic setup: kV - rectifier, Fg - forming a spark gap, W - working cell of the
electrohydraulic drilling, C - capacitance of the capacitor.
The laboratory equipment consists of the following units: control panel, a system protective
capacitor, an electric power supply, current limiter, automatic power off, a high voltage indicator,
commutation generator, high voltage rectifier of the transformer, power storage devices, the
protective system of the capacitor, residual voltage removing unit, protection system, a small
discharger, an electrode system. To carry out experiments on the destruction of stones in the drilling
process, a working cylindrical cell was made, the bottom of which has a hemispherical concave
shape (its thickness together with the insulating material is 13mm). To hold the electrode in the cell
body at the same position attachments are mounted. The negative electrode of the electro-hydraulic
setup is placed at the bottom of the cylindrical cell. In Figure 2 and Figure 3 the working cell of the
electro-hydraulic setup is shown.
Fig.2. Working cell for drilling.
Fig.3. Working cell, mounted on a stone.
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22 ISSN 1811-1165. Eurasian Physical Technical Journal, 2012, Vol.9, No.2(18)
The thickness of the stones used for the investigation in the laboratory of hydrodynamics and
heat and mass exchange, was different (h = 30mm, h = 40mm, h = 70mm). The best results were
obtained at a gap length of 9 mm in the discharger of the electro-hydraulic equipment.
As a result the experimental study, the optimal values of time and quantity of spark discharges
during the electrohydraulic drilling of stones, as well as the time when the cracking of the stone
took place in the drilling process were determined.
The experimental results of electrohydraulic drilling of stones with h = 30 mm, h = 40 mm are
shown in Figures 5 and 6.
Fig.5. Break of the stone after
drilling for 3 minutes (h = 30mm)
Fig.6. Break of the stone after
drilling for 5 minutes (h = 40mm)
Figure 7 shows that at the thickness of the of stone h = 30mm-40mm the number of discharges
prior to crushing was 150-200 impacts and for h = 70 mm it was 400-450 impacts. Drilling depth
depends on the number of impact discharges. At the maximum impact discharge, the rate of
increase in drilling depth grows. The reason is that at the impact discharge an increase in pressure
takes place, it causes the lump grinding on the surface of a stone. An increase in the impact of a
ЭГУ
Fig. 4. Scheme of the electro-hydraulic drilling: 1– electrode, 2 – cell, 3 – stone.
-
Heat Physics, Hydrodynamics, Energetic 23
discharge leads to pressure growth, so at the maximum impact of an electric discharge the depth of
drilling is increased.
0
50
100
150
200
250
300
350
400
450
20 30 40 50 60 70
H, мм
n
Fig.7. Dependence of the number of impact discharges on the thickness of a
stone prior to crushing.
Figure 8 shows a graph of dependence of the impact discharges number on the length of time
of the drilling process
0
50
100
150
200
250
300
350
400
450
0 2 4 6 8
t, мин.
n
Fig.8. Dependence of the number of impact discharges on the time length at a
electro-hydraulic effect.
The dependence of the number of impact discharges on the length of time at a electro-hydraulic
effect was established. As it is shown in the graph, in the process of crushing of stone (h = 40 mm)
the number of spark discharges amounts to 50 impacts per minute, 150 impacts in two minutes, 200
impacts in three minutes, 350 impacts in seven minutes. It was found out that during the process of
drilling, the stone surface begins to grind and eventually the drilling depth increases, and
consequently this increases the frequency of electrical discharges.
REFERENCES
1. The Energy Strategy of the Republic of Kazakhstan for the period 2004-2015.- Astana.
2. Ray D., Mcmichael J. Heat Pumps. - Moscow: Energoatomizdat, 1982.-224 p.
3. Vasiliev G.P. The use of low-grade heat the soil surface layers of the earth to the refrigerant heat supply of
buildings // Thermal Engineering. - 1994. - № 2.- P.31-35.
4. Yutkin L.A. Electro effekt.- M.: Mashgiz, 1955. - 51 p.
5. Yutkin L.A. Electro-effect and its application in industry. - A: Engineering. - 1986. -253 p.
Article accepted for publication 18.07.2012
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24 ISSN 1811-1165. Eurasian Physical Technical Journal, 2012, Vol.9, No.2(18)
UDC 53.096
RECYCLING OF SILICON CARBIDE AND SILICON FROM WAFER SAWING SLURRY
T. Neesse1, J. Dueck1, E. Endres1, L. Jakob2
1FAU Busan, Republic of Korea, 2SiC Processing GmbH Hirschau, Germany [email protected]
In the production of silicon wafers for the photovoltaic industry a wafer saw cutting process is
employed to slice the mono- or polycrystalline ingots to wafers. For that, multi-wire sawing using SiC slurry
is the main slicing technology in photovoltaic (PV) and semiconductor (SC) industry. The cutting process
produces a large quantity of saw dust (kerf). Dependent on the wafer thickness and the diameter of the
cutting wire, the amount of sawing chips yields up to 30 – 50% of the ingot weight. This residue contains
mainly the abrasive SiC, the Si-abrasion and Fe with other metals coming from the saw wire in a suspension
of polyethylen glycol (PEG). They thus constitutes valuable materials which are well suited to be recycled to
the photovoltaic industry. A solution of the waste slurry problem is unfortunate, both from an economical
and environmental point of view. This paper reports on different concepts and own experiences related to Si
and SiC recycling.
Keywords: Si-Recycling, SiC-Recycling, Trichlorosilane, Hydrocyclone.
Introduction
Over 80 % of the global solar cell production requires the cutting of silicon blocks into wafers
[1]. For that, multi-wire sawing using SiC slurry is the main slicing technology in photovoltaic (PV)
and semiconductor (SC) industry. During sawing a large amount of slurry is produced, which
contains polyethylene glycol (PEG) as suspending fluid, silicon carbide (SiC), iron and silicon.
Much attention is paid to recycling of SiC and PEG to the sawing process. The base publication in
this direction is an article by Neesse [2], where the variants of SiC recycling from wafer sawing
slurries are reported.
These technologies have reached a high standard and are industrially applied.
On the other hand, Si –recycling from wafer sawing residues is much more difficult and
challenging and has been subject of a large European Project [3] (Recycling of Silicon Rejects,
2006) Methods for this are actually still in the development.
After reporting on SiC recycling in this paper options and limitations of physical Si-separation
processes are reported. High grade solar Si can be achieved applying combined physical and
chemical treatment considering a special chemical technology were Si is reacting with chlorinated
acid to trichlorosilane [4-6]. First experiences with this process are reported.
1. Recycling of SiC
The SiC- recycling technology should fulfil the following requirements:
Production of PEG and SiC of a quality, comparable with virgin material
User-friendly handling of the recycling products
Consideration of environmental aspects for the separated residues As can be seen from Fig.1, two variants are to consider: The “in-house” approach consists of
equipment that the semiconductor- manufacturer purchases, sometimes offered during the original
saw purchase, and runs in-line with their own slurry system. In the US these systems exist in many
wire sawing plants.
The alternative is outsourcing the SiC-recycling to a specialised recycling company. The
recycler can operate an on-site system using mobile equipment or requires the manufacturer to
transport the slurry to a stationary recycling plant (off-site-system).
-
Methods and technologies of new materials 25
Fig.1. In house-(a) and outsourced (b) SiC recycling [2].
Necessary steps of SiC recycling are the separation of liquid medium PEG by filtration and
separation of SiC as recycling products from the contaminants by hydroclassification. The
contaminants are fine dispersed Si, SiC and Fe.
As classifiers in the range with cut sizes of of about 10 µm Decanter centrifuges and
hydrocyclones are available. The decanter centrifuges spin at a high rotational speed and the
classification is accomplished because the particles settle with different settling rates dependent on
their size. Due to the fact that all particles (more or less) settle, the decanter is more a solid/liquid
separator than a classifier.
A marked portion of particles < 5mµ (contaminants) is misplaced and discharged together with
the coarse SiC-particles (recycling product). The remaining contaminants from even the most
elaborate decanter technologies are generally ~3-4%. The enrichment of fine particles in the
recycled SiC-product leads in the closed circuit to a deterioration of the suspension properties.
Under these conditions only 3 – 4 passes of the slurry through the sawing process can be carried
out. In this regard, the use of hydrocyclones deliver better results.
At present, the tendency seems to increase that semiconductor- manufacturers (because of
overall-cost improvement) replace the “in-house” system running their entire slurry volume with an
outsourced system. An enhanced outsourced system in a stationary plant prefers a multistage
technology. The market leader describes a plant scheme in Fig.2 consisting of following steps [2]:
1. Separation of PEG 2. Cleaning of PEG 3. Separation of SiC 4. Cleaning of SiC 5. Drying of SiC 6. Conditioning of SiC It is obvious that a multistage cleaning can approach the final SiC-product to zero-
contamination. Therefore, the number of passes of slurry through the sawing process is not limited.
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26 ISSN 1811-1165. Eurasian Physical Technical Journal, 2012, Vol.9, No.2(18)
Fig.2. Multistage technology of SiC processing [2].
Further, multi-stage systems show higher cost effectivity, if a well sophisticated process
sequence is found avoiding expensive centrifuges. Additionally, the specific costs per ton are
reduced due to the high throughput of a stationary plant.
Outsourced systems have to answer the demands of user- friendly handling of the recycled
products. Applied is the transport of wet SiC products which are discharged from hydroclassifier
without further drying and cleaning. The material must be reconstituted with carrier into slurry. This
means that the manufacturer is forced to install equipment to remix the slurry after the transport
because the solids will settle in the containment.
More appropriate are products separated into dry SiC powder and PEG. The manufacturer has
three options to receive SiC and PEG from the recycling plant:
1. Separated delivery of reclaimed SiC powder and reclaimed PEG. Slurry preparation by
adding of virgin material at the manufacturer.
2. Separated delivery of reclaimed SiC powder mixed with virgin SiC powder and of reclaimed
PEG mixed with fresh PEG (slurrying is performed at the manufacturer).
3. Delivery of a ready mixed slurry consisting of SiC (reclaimed and virgin) and PEG (
reclaimed and virgin ), In this case no slurry preparation at the manufacturer.
In the EU a tendency of increasing outsourcing the entire slurry preparation to the recycler can
be observed.
2. Recycling of Si
Concerning Si there are two concepts for the recycling: Production of a low grade metallurgical
Si or production of solar Si. The first variant can be achieved using only physical separation
processes.
High grade solar Si can be achieved applying combined physical and chemical treatment.
-
Methods and technologies of new materials 27
3. Physical separation of Silicon
The feed for the Si-recycling was dried filter cake with 24% moisture, as it occurs typically in
the SiC (Silicon carbide) recycling from the wafer production at a separation cut at 10 microns. As
further components after SiC were 9.5% iron, 31% elemental silicon and 1.8% polyethylene glycol
were determined. The initial particle size distribution of material after intense dispersing can be
found in Fig.3.
Fig.3. Volume fractions of particles in the SiC/Si suspension with enriched fine Si particles
As can be seen from Fig. 3, the material contains finest Si-abrasive in the range 0.1 – 0.3 µm
and coarser silicon carbide SiC. The gap between the fine and the coarse portion delivers an
advantage for the hydroclassification.
This material was used as a feed for a special 20mm-hydrocyclone, which operated in closed
circuit duration 60 min [7]. Because no fluid is discharged in the underflow, the suspension can be
kept indefinitely in the circuit as can be seen in Fig.4.
Fig.4. Scheme of the hydrocyclone test rig with closed circuit and attached
accumulation box for the underflow.
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28 ISSN 1811-1165. Eurasian Physical Technical Journal, 2012, Vol.9, No.2(18)
Fig. 5 and 6 show the final particle size distributions of the coarse product and of the overflow,
respectively.
Fig.5. The final volume fractions and cumulative particle size distributions in the coarse product of the
hydrocyclone.
Fig.6. The final volume fractions and cumulative particle size distributions in the fine product of the
hydrocyclone.
As can be seen, the overflow contains only particles < 0,3 µm. The chemical analysis of this
Silicon-concentrate have shown that Si contents 90 – 95 % may be achieved. Due to the high
specific surface the Si-particles are covered with silicon oxide and adsorbed metal ions of this
product . This indicates the limit of the physical Si-recycling. Even acid leaching did not deliver an
acceptable cleaning to produce high grade solar silicon.
-
Methods and technologies of new materials 29
5. Thermo-chemical separation of Silicon
The goal of these tests was to successfully perform the hydrochlorination of silicon metal in
waste filter cake and to recover a condensed sample of the product, trichlorosilane (TCS). By-
products of this reaction include also dichlorosilane and silicon tetrachloride. The reaction summary
is written below.
3 HCl (g) + Si (s) → SiHCl3 (g) + H2 (g) – 218 kJ/mol
Details on the chemistry of this reaction can be found for example in [4-6].
This equation requires gas to solids contact. Fluid bed treatment provides excellent solids-gas
contact and heat transfer. Hydrogen chloride is thereby used as the fluidizing gas stream in an
indirectly-heated fluid bed reactor with integrated filter head. The process gases used included only
anhydrous HCl and nitrogen. For each test, a quantity of starting solids was loaded, heated to
temperature under nitrogen, and reacted with HCl gas.
The starting material for these tests was in the form of solid dispersed filter cake, containing
silicon carbide (60-80%), iron (5-10%), and silicon metal (15-30%).
The process employed to accomplish the objectives of the testing involved the use of a fluid
bed reactor system, using nitrogen and hydrogen chloride as fluidizing gases. The solids bed was
loaded, fluidized on nitrogen, and heated to the operating temperature where the reactant gas, HCl,
was introduced either at 100% concentration or as a partial atmosphere in nitrogen.
6. Lab scale
The experiments were carried out at a flow apparatus [4], shown in Fig. 7. The test rig was
equipped with a glass-vibration reactor of about 35 ml volume. The reactor is equipped with a
rotating vibrator, which leads to a fluidized bed of the reactive silicon-containing material. The
experiments were carried out at atmospheric pressure and the specified reaction temperatures. HCl
was used undiluted. All experiments were executed with a HCl standard flow rate of 1.26 l / h
(room temperature). The reactor heating was an electrically operated radiant oven. The reaction
products were analyzed online by gas chromatography.
Fig 7. Test Rig for trichlorosilane (TCS)-Synthesis.
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30 ISSN 1811-1165. Eurasian Physical Technical Journal, 2012, Vol.9, No.2(18)
The gas chromatogram in Fig.8 indicates trichlorosilane (TCS) dichlorosilane (DCS), and
silicon tetrachloride (STC) as products of the reaction.
Product selectivities are dependent on the reaction conditions, especially temperature,
residence time and catalytic additions.
The use of Cu powder and CuCl as potential catalysts for accelerating the reaction and / or
influencing the selectivity has been tested. These additions have a marked effect on the reaction and
may even be a precondition for the technical usability of the TCS- reaction. Under appropriate
conditions (variation of T and catalyst) high HCl - recoveries of about 90% TCS, and on the other
hand even high selectivities of 90% can be achieved.
Fig. 8. Typical gas chromatogram of chlorination.
A typical run of completeness and selectivity of the reactions is shown in Fig. 9.
Fig 9. Typical run of completeness and selectivity of the reactions.
-
Methods and technologies of new materials 31
Figure 9 indicates that the reaction at the beginning is inhibited and starts at the reaction
temperature of > 330 0 C after 80 min, than developing with increasing completeness of the
reaction. The resason for the inhibition may be the blockage of the Si-surface by oxide layers [6].
7. Pilot scale
Referring to Fig. 10, a series of experiments were performed using a 6”-diameter fluid bed
reactor constructed entirely of high temperature alloys, with graphite gaskets for the flange
connections. The unit was equipped with a screw plate gas distributor and Fines Retention Filter
System. Nitrogen was used as blowback gas to clear filters. This vessel was submerged in an
electric indirectly heated fluidized Sand Bath. A custom manifold was constructed to meter both
nitrogen and hydrogen chloride.
Fig. 10. Pilot scale fluid bed system [8].
The hydrochlorination reaction is exothermic, increasing the temperature of the solids bed.
Total flow rate of gases were maintained to keep the solids bed fluidized. These bed temperatures
were controlled by limiting HCl in the fluidizing gas.
The reaction is exothermic and the rate of the reaction, once the activation energy is sufficient,
increases as the temperature is driven up according to Arrhenius equation. In perfect fluidization,
this additional heat is transferred evenly within the fluidized solids bed. Fluidizing gas enters the
reactor, is in contact with the solids bed, and exits the reactor through the filters. Also exiting the
filters is any additional blowback gas clearing the filters. Certain exothermic activity was seen
throughout the solids bed in the familiar trend seen in Fig.11. This is characterized by an increase in
the upper bed temperatures followed by a delayed, higher temperature increase in Bed Low. The
temperature profile indicates the strongly exothermic character of the reaction. To stabilize the
reaction, at high temperature gradients the dosage of HCL was down regulated.
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32 ISSN 1811-1165. Eurasian Physical Technical Journal, 2012, Vol.9, No.2(18)
Fig.11. Temperature Profiles and HCL Mass flow Rate [8].
A condenser was built to condense liquids and solids in the reactor off-gas generated during the
tests. The single stage condenser was cooled by solid carbon dioxide (dry ice) in a bath of ethylene
glycol, which held the condensate/vapor stream between -10°C to -20°C. The temperature is enough
to condense the compound of interest, trichlorosilane, as well as other by products of the reaction.
The solids bed was loaded, fluidized on nitrogen, and heated to the operating temperature where the
reactant gas, HCl, was introduced either at 100% concentration or as a partial atmosphere in
nitrogen.
The batch, which was deemed the most successful of the trials, exhibited a mass loss of 37.1%
the material loaded. If 10% was lost from iron hydrochlorination and 5% to volatiles, then a 22.1%
is likely lost due to silicon reaction. This mass loss falls well within the determined silicon content
of the feed.
Summary
In recent years the problem of recycling of SiC and PEG to the sawing process has achieved
substantial progress. The recycling of SiC from wafer sawing slurry is already used industrially.
High modern technology fulfills the following requirements:
a) PEG and SiC can be produced of a quality, comparable with virgin material, b) the recycling products can be user-friendly handled, c) environmental aspects for the separated residues are considered. An enhanced outsourced system in a stationary plant prefers a multistage technology. The
recycling plant consists of following steps: separation of PEG, cleaning of PEG, centrifugal
separation of SiC, cleaning of SiC, drying and conditioning of SiC.
However, Si –recycling from wafer sawing residues is much more difficult and challenging.
Methods for this are actually still in the development. Concerning Si there are two concepts for the
recycling:
a) Production of a low grade metallurgical Si or production of solar Si. This can be achieved using physical separation processes. The options and limitations of physical separation processes
are reported.
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Methods and technologies of new materials 33
b) High grade solar Si can be produced applying combined physical and chemical treatment considering a special chemical technology were Si is reacting with chlorinated acid to
trichlorosilane.
REFERENCES
1. Moeller H.J.. Basic Mechanisms and Models of Multi-Wire Sawing. Advanced Engineering Materials 2004. -
V.6. - N 7. - P. 501-513.
2. Neesse, T., Review on SiC-recycling in wafer sawing operations, Intercam. – 2006. - V. 55. - N.6. P. 430-432. 3. Recycling of Silicon Rejects from PV Production Cycle, European Reference: NNES – 2001-00175, 2005. 4. Kürschner U., Pätzold U.,
Hess
K.and Lieske H.. Studies on Trichlorosilane Synthesis. In Silicon for the
Chemical Industry VII MS Trollfjord, Tromso-Bergen, Norway, Sept. 21-24, 2004 Ed.: H.A. Oye, A. Holas, L.
Nygaard, Trondheim, Norway. – 2004. - P.177-188.
5. Lobreyer T., Hesse K., Ehrich H., Lieske H. Proceedings of "Silicon for the Chemical Industry IV", Trondheim, Norway. – 1998. – 11 p.
6. Becker, F. Modeling and Simulation of hydrochlorination of silicon to trichlorosilane for the development of a technical fluidized bed reactor ( in German). Dissertation, Rheinisch-Westfälischen Technischen Hochschule Aachen. -
2005.
7. Endres,E., J. Dueck, J. and Th. Neesse, Hydrocyclone Classification of Particles in the Micron Range. Proceedings of Physical Separations 11, 2011 Falmouth, UK.
8. Technical report NO. TR-FBC-09-04, Trichlorosilane Synthesis in a Fluid Bed. SiC Processing AG Hirschau, Germany September 24, 2009.
Article accepted for publication 04.09.2012
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34 ISSN 1811-1165. Eurasian Physical Technical Journal, 2012, Vol.9, No.2(18)
UDC 537.528, 621.7
GRINDING TECHNOLOGY OF SILICON METAL
B.R. Nusupbekov, A.K. Khassenov, A.Zh. Beisenbek
Karaganda State University named after E.A. Buketov, Universitetskaya str. 28, Karaganda, 100026, Kazakhstan,
In article is presented application silicon, and advantage him(it) in contrast with the other
semiconductor. The aims and purposes of processing of metallurgical silicon electrohydraulic way.
Proposed optimal processing parameters of the product. The Certain admixture other element in
composition metallurgical silicon processed электрогидравлическим way, and got given are compared to
product reduced in mechanical grinder. Processing metallurgical silicon on электрогидравлическим
installation does not require the greater expenses for reception powder silicon in necessary proportion
Keywords: electro-technology, metallurgical silicon.
There are many debates in the modern Kazakhstan's science about how to correctly call the
material containing 95 to 99% by weight of pure silicon. Some call it the Silicon metal, some
metallurgical, some of silicon. For the purposes of this review, we use the following terms:
Industrial silicon is a material with a silicon content of more than 95%, and suitable for use in
electronic and chemical industries.
Metallurgical silicon is a material with a silicon content of 50 to 95% and is used in the
production of aluminum, iron and steel. Since in most cases, used in metallurgy alloys contain
silicon except as iron, in this report we refer to as the silicon metal and ferrosilicon ferroalloys.
Silicon metal is a broad category that combines both technical and metallurgical silicon.
Silicon metal is brittle mineral gray, weak ties which prevents the use of the mechanical
properties, but which has been widely used as an alloy for steel and as the basis for the production
of silicone products and subsequent forms of silicon.
In an alloy with iron, silicon in the form of ferrosilicon is used for making acid-products, mainly
in metallurgy for deoxidation and alloying. There is a production of 50% x (the majority) and 75%-s
grades of ferrosilicon.
Industrial silicon is mainly used in the aluminum and chemical industries. Thus, about 54% of
the world's commercial silicon directed to manufacture aluminum-silicon alloys, in which the silicon
content is only about 6%. These alloys are used in the automobile industry, and the average content
of Al-Si alloy car ^ 1995-1999 year is 945 kg [1, 2].
To obtain further redistribution of silicon, namely polycrystalline and monocrystalline silicon,
used pure grade silicon, samples of which are shown in the figures. This type of silicon - Technical
KpeMHnq chemical quality, is divided into several classes: 441, 3303, 2202. The numbers in the
name refer to the number of grades of silicon impurities present in the material. So widespread
grade 553 should contain no more than 0.5% iron, 0.5% aluminum, 0.3% calcium.
According to studies of fossil fuels by 2020 can satisfy world energy only partially. The rest
of the energy demand can be met by renewable sources.
Among the solutions to environmental problems related to the depletion of fossil fuels, an
important place direction, based on the direct conversion of solar energy into electricity using solar
cells. This solution of the energy problem is very attractive to environmentally friendly, using
virtually inexhaustible source of energy, lack of long-term cycles of heating and rotating
machinery.
Many countries are working to develop the production of solar energy converters based on
silicon "solar" as the quality of material, favorable for photovoltaic cells (PEC), the physical-
chemical properties and high level of modern production technologies. However, the development of
mailto:[email protected]
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Methods and technologies of new materials 35
this area is constrained by the high cost of the trichlorosilane process unit received power compared
to conventional energy sources.
In industry, silicon is obtained by restoring coke SiO2 melt at a temperature of about 1800 ° C
in electric arc furnaces. The purity of such silicon is about 99.9%. Because the need for the practical
use of higher purity silicon, the silicon is chlorinated. The formation of compounds of SiCl4 and
SiCl3H. These chlorides further purified in various ways from impurities and the final stage of
restoring pure hydrogen. It is also possible cleaning silicon due prior magnesium silicide Mg2Si.
Next of magnesium silicide with hydrochloric or acetic acid are volatile monosilane SiH4.
Monosilane further purified by distillation, sorption and other methods, and then decomposed into
silicon and hydrogen at a temperature of about 1000 ° C. The content of impurities in the product of
these methods is reduced to silicon 10-8-10-6% by weight. Currently, silicon is the basic material
for electronics. Monocrystalline silicon is used to mirror gas lasers [3].
Besides silicon is the leading modern semiconductor material, which is widely used in
electronics and electrical engineering for the manufacture of integrated circuits, diodes, transistors,
thyristors, solar cells, etc. In the first phase of development of microelectronic production as a raw
material used germanium (Ge). Currently, 98% of the total number of integrated circuits made of
silicon.
Raw material for the microelectronics industry is the electronic polycrystalline silicon, which is
then obtained from single-crystal ingots with the necessary physical properties.
The final silicon is a mirror on one side polished single-crystal plate of diameter 15 - 40 cm
and a thickness of 0.5 - 0.6 mm with different orientation of the surface.
Industrial silicon is used as an alloying component in steel production (eg, transformer steel)
and non-ferrous metal (silicon bronze). Ultra-pure silicon is used as a semiconductor. Over 90% of
solar cells made from silicon. At the moment, it is the optimal material for the conversion of
sunlight into electricity. Other materials have a low efficiency and high cost. Industrial uses solar
power silicon solar cells with an efficiency of 14-16%. In the experimental production of silicon
squeeze 26% efficiency, but the cost of laboratory samples is much higher production solar cells [4,
5].
Economically feasible to establish commercial silicon of high purity of at least 99.90%.
Production of such silicon is only possible if supequartzitic deposits with a minimum total content
on the main contaminants - boron, aluminum, phosphorus, iron, calcium, less than 40 ppm. Quartz
deposits of Kazakhstan meet such requirements for cleanliness and elemental composition and
quartzite reserves of more than 6.8 million tons.
Therefore, in the laboratory of hydrodynamics and heat transfer of Engineering Thermophysics
named after prof. Zh.S.Akylbaev of Karaganda State University named after E.A. Buketov
developed and assembled electrohydroimpulse installation, based on the use of pulsed shock wave
resulting from the spark discharge in a liquid for crushing and grinding of metallurgical silicon [6-
8].
In the experiments the initial diameter of the silicon particles averaged from m fineness
increases with specific energy input into the discharge channel, which is explained by the fact that
in the processed ore first formed a network of micro-cracks in the path of the shock wave, which
creates a continuous state of stress
Unlike mechanical crushers electro setting has no moving parts, much is made of conventional
structural steel, so the body is almost no wear at work. The main factors affecting the grinding
mechanism, are the intensity of the pulse pressure wave, its duration, the nature of energy input in
the discharge channel, the total length of the grinding process, high velocity fluid, formed as a result
of volume microcavitating
Experiments were conducted on electrohydropulse installation at different discharge energy,
distance between electrodes on the switching device (Figure 1), capacitance capacitor bank (Figure
2), and pulse repetition rate
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36 ISSN 1811-1165. Eurasian Physical Technical Journal, 2012, Vol.9, No.2(18)
Fig.1. The dependence of the degree of decomposition of silicon the size of the interelectrode distance.
Fig. 2. The dependence of the degree of decomposition of silicon capacity capacitor bank.
From these graphs it can be concluded that increasing the distance between electrodes and
capacitance capacitor bank large diameter particles are crushed intense and there is a general
pattern of an electric discharge in liquid. The data obtained allows to choose the optimal value of
the interelectrode distance requirefor playback experiments.
Below in Figures 3 and 4 it is shown the experimental results of the processing of silicon
metal electrohydroimpulse before and after exposure.
Fig.3. The experimental results of the processing of silicon metal before and after
electrohydroimpulse exposure and percentage of pure silicon.
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Methods and technologies of new materials 37
Fig.4. The experimental results of the processing of silicon metal before and after
electrohydroimpulse exposure and percentage of items.
As can be seen from the figures, the content of impurities in the medium can be reduced by
applying electro-way. However, after a certain period of time, the percentage of Si treatment
increased from 99.73% to 99.94%, and the sulfur is reduced from 58 to -4 ppm, titanium from 45 to
9 ppm, manganese from 105 - up to 40 ppm, of boron 322 to 115 ppm, vanadium from 3 to 0 ppm;
barium 6 to 1 ppm.
Thus, the impact of implemented with an underwater spark discharge, lead to the destruction of
metallurgical silicon with subsequent reduction of alkaline and heavy non-ferrous metals and a
simultaneous increase in the elemental composition of silicon.
The results showed that, electrohydroimpulse method of grinding allows you to adjust size
distribution of the finished product with high selectivity. The proposed method and power
installation options are best suited to industrial environments, provides intensive crushing and
grinding of metallurgical silicon. These studies and the implementation of their results to the
enterprises will promote technical progress in the industry.
REFERENCES
1. Samsonov. G. V. Silicides and their use in engineering. Kiev, 1959. - 204 p.
2. Semiconductor silicon technology // under publish. E.S. Filkevich. - М.: Metalurgiya, 1992. – 408 p.
3. Katkov О.М. Smelting of silicon. Irkutsk: publishing house IPU, 1997, - 243 p.
4. Balagurov L.L. Porous silicon: Preparation, properties, areas of application // Materials Science. – 1998.
5. Nemchinova N.V. Belsky S.S., Krasin B.A. High-purity metallurgical silicon as a basic element for solar energy
/ / Success of modern natural science. - M., 2006 - № 4. -P. 56-57.
6. Yutkin L.А. Electrohydraulic effect and its application in industry. - A: Engineering, Leningrad Branch, 1986. –
253p.
7. Guly G.А. Scientific basis of the discharge-pulse technology / / SSR PCB Electrohydraulics. - Kiev: Nauka.
Dumka, 1990. - 280 p.
8. Nusupbekov B.R. Shaimerdenova G.M. Kusainova D.K. Dynamics of destruction and formation of structures in
the process of electroimpulse processing of silicium minerals. Eurasian Physical Technical Journal. – 2008. – Vol.5. –
№1(9). – P. 24-28. Article accepted for publication 09.07.2012
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38 ISSN 1811-1165. Eurasian Physical Technical Journal, 2012, Vol.9, No.2(18)
UDC 539.26 THE STUDY OF THE COMPOSITION OF THE NATURAL
NANOSTRUCTURED MATERIAL - CHRYSOTILE ASBESTOS
Medetov N.A.
Scientific Research Institution “Moscow State Institute of Electronic Technology - MIET”, [email protected]
The article discusses the properties of the natural nanostructured material - chrysotile asbestos. The
object of the research is produced at the minefield in Zhitikara, Kostanai region. Some areas for possible
applica