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DEVELOPMENT OF HIGHLY EFFICIENT EQUIPMENT BASED ON FUNCTIONAL CERAMICS SYNTHESIZED IN A SOLAR FURNACE WITH A CAPACITY OF 1 MW
Rakhimov Rustam Kh., doctor of technical Sciences, head of laboratory № 1, Institute of materials science «Physics-sun», Uzbekistan Academy of sciences. Tashkent, Uzbekistan. E-mail: rustam-shsul@yandex.com
Abstract. The Aim of this work is to study the pulse systems based on ceramic materials synthesized on a solar furnace with a capacity of 1 Megawatt
Keywords: ceramic materials, oxide materials, infrared converters, optical ceramics, glass-crystal materials, chromites of rare earth elements, cordierite, corundum, technological process, pulse systems
РАЗРАБОТКА ВЫСОКОЭФФЕКТИВНОГО ОБОРУДОВАНИЯ НА ОСНОВЕ ФУНКЦИОНАЛЬНОЙ КЕРАМИКИ, СИНТЕЗИРОВАННОЙ НА СОЛНЕЧНОЙ ПЕЧИ МОЩНОСТЬЮ 1 МВт
Рахимов Рустам Хакимович, доктор технических наук, зав. лабораторией № 1 Института материаловедения НПО «Физика-Солнце» АН РУз. Ташкент, Узбекистан. E-mail: rustam-shsul@yandex.com
Аннотация. Целью настоящей работы является исследование импульсных систем на основе керамических материалов, синтезированных на солнечной печи мощностью 1 мегаватт
Ключевые слова: керамические материалы, оксидные материалы, инфракрасные преобразователи, оптическая керамика, стеклокристаллические материалы, хромиты редкоземельных элементов, кордиерит, корунд, технологический процесс, импульсные системы
One of the main problems that came to the fore in recent years was the problem of economical expenditure of material, technical and fuel and energy resources. The problem of preserving and processing agricultural products is also acute, since full-value nutrition is an integral part of a healthy lifestyle. In connection with this, the number of research and development on the use of alternative, mainly renewable, types of energy has significantly increased. However, it is hardly possible to solve the problem on a global scale with such a one-sided approach. It is also necessary to solve the problems associated with insufficient energy efficiency, no matter what form it is used for. Analysis of energy-intensive processes shows that there are huge reserves to reduce energy consumption.
In recent years, new progressive technologies for the efficient use of energy in industry, agriculture, baking and other spheres are developing rapidly. In addition, new alternative methods are developing in medicine [1, 2, 4, 8, 10, 11, 15, 20, 30, 34, 36, 38, 40, 41, 46, 49, 51].
One such direction is the development and use of various ceramic materials for use in these areas. However, the possibilities of the available methods for planning the complex of specified properties, synthesis and processing of such materials are extremely limited. This is due to the fact that they are obtained mainly by the solid-phase method or by the method of coprecipitation. These methods have significant limitations and drawbacks, which are either insurmountable, or overcome by too much resource expenditure. In addition, it is fundamentally impossible to obtain some important properties and characteristics of target materials by these methods.
Synthesis of materials from the melt gives significantly better results, as it goes in the liquid phase and the process accelerates
hundreds and thousands of times. In addition, many complex composites can not be obtained in any other way. Another problem is the problem of contamination or disturbance of the stoichiometry of the target product, which does not allow obtaining materials with a set of specified properties, which are the basis of functional ceramics.
The construction and commissioning of the Big Solar Furnace (BSF), with a capacity of 1 MW in Parkent, made it possible to realize technological opportunities in the synthesis of ceramic materials with a set of specified properties. The advantages of this method with the use of solar energy are obvious [6, 10, 17, 20, 50]:
• there is no contamination of the target materials;
• the possibility of simultaneous purification during synthesis;
• variation in the heating rate over a wide range;
• the ability to control the cooling rate, which allows you to obtain materials of a given structure;
• the possibility of obtaining complex composites;
• the materials have a structure that can not be obtained by conventional methods, which makes it possible to realize the characteristics for operation in extreme and severe operating conditions;
• the possibility of a combination with any other method in the technological chain of synthesis of target materials, etc.;
• the synthesis occurs in the liquid phase, which causes the completeness of the synthesis and the stoichiometry of the target material, and the process is accelerated hundreds and thousands of times;
• heating of the initial components is carried out, practically non-inertial;
• the substance is affected by a powerful photon flux with a very wide set of energies, resulting in the formation of all possible
metastable states for a given substance or compound. This leads to distortions of the crystal lattice. As a result, the heat resistance and strength of the target material increases sharply, since no secondary recrystallization and crack growth is observed above the critical size value;
• in the process of synthesis, all photochemical processes allowed in this energy range occur.
In temperature furnaces synthesis occurs due to passage of energy by conductive or convective way. The main carriers of energy in this case are phonons. When using laser radiation, the effect goes in a very narrow spectral range. This makes it possible to obtain materials with perfect structure. However, products made from such material tend to secondary recrystallization, which leads to a decrease in their physicomechanical and electrophysical characteristics.
With the use of the plasma method, due to the effect of the electron flow, materials with a chemically reduced form are synthesized, which is reflected in the main characteristics of the target materials.
Thus, concentrated solar energy is an important component in the arsenal of methods for synthesizing materials with a set of specified properties.
A system for calculating the composition and technology of synthesizing materials with a set of specified properties was developed, including the «Visual Kinetics» software package, which allowed calculating the kinetic part of the process, which greatly accelerated the optimization of the necessary technological chain [6, 50].
• Effective methods for stabilizing the stoichiometric composition of the target materials under conditions of extremely uneven heating on the BSF have been developed.
• A highly effective technology for producing multi-layer ceramic materials has been developed.
• Application of the developed principles and approaches, as well as multi-layer structures, allows to create high-temperature ceramic heaters with high operating parameters.
• The use of functional ceramics in drying devices for loose ingredients (chalk, kaolin, soot, zinc white, sulfur, rosin, thiuram, microcalcite, etc.) allows to increase productivity by 3 times, to reduce energy intensity by 3 times and to obtain a total gain in energy saving in 9 times.
• The use of functional ceramics for drying various objects leads to a significant reduction in energy consumption and drying time. Many energy- and labor-consuming operations, necessary for old technologies, become unnecessary. For example, when drying molds, there is no need to use the filling of the molds with quartz balls; and there is no need to use special metal boxes. It is shown that the use of functional ceramics for drying plastics not only saves energy and shortens the time of the process, but also makes it possible to significantly reduce the size of drying installations and improve the quality of the target product, since no polyamide oxidation takes place and its color does not change [- When drying walls and other similar objects, the efficiency of such dryers is much greater than analogs, it destroys mold and fungi, and does not damage plastic or other parts, such as cables, pipes, etc. [1].
• The use of functional ceramics in sterilization systems can significantly improve their reliability and efficiency, does not lead to damage of the instrument, and also reduces the sterilization temperature, energy consumption and significantly reduces the sterilization time. In addition, it is easy to use and operate such sterilizers [10].
• The use of functional ceramics has made it possible to develop harmless infrared ceramic emitters that have a selective effect only on pathologically altered organs and tissues, which allows normalizing metabolic processes at the molecular level.
• Infrared emitters have been developed for the prevention and treatment of immune, endocrine, acute and chronic somatic, infectious, viral, oncological and other diseases [38, 40, 41, 46].
Comparative efficiency of the application of functional
ceramics for various processes is given in table 1.
Table 1
Efficiency of application of functional ceramics for various processes
Object Ratio reduction in time / where the tests were conducted Ratio reduction of consumed energy / decrease in drying power Enhance the effectiveness / how many times
Polymer film containing 0.1-1% ultradisperse powder of impulse ceramics at helio drying The speed of drying with the use of ceramics increased by 30-50% Germany A photon with an energy of 1.2-2 eV can theoretically create photons more than 10 photons with energy 0,1-0,2 eV 1.3-2.0
Conveyor drying of pasta 60 min / 7.5 min Germany, Kazakhstan, Uzbekistan 31 000 watt per hour / 1175 W per hour 26 / significantly higher quality of the obtained target products at the same time sterilization of product occurs
Drying of loose materials such as kaolin, chalk ext. 3 times / Uzbekistan, Germany 3 times 9, significantly higher quality of the obtained products
Drying of rice, grain, fruits and vegitables 2-4 times / Uzbekistan, Germany, Kirgizstan, Russia Significantly higher quality of the obtained products, easy to use technology, at the same time sterilization and total liquidation of fungi
Conveyor drying of rice and vegetables in high humidity conditions 1.6-3.5 times, Vietnam, Malaysia, Germany 1.6-3.5 times/ Very easy to use technology, significantly higher quality of the obtained target products, at the same time sterilization and total liquidation of fungi
Table 1
Object Ratio reduction in time / where the tests were conducted Ratio reduction of consumed energy / decrease in drying power Enhance the effectiveness / how many times
Drying of industrial catalysts 240 hour / 3 hour Germany 110 watt per hour / 0,1 watt per hour More than 1000 times / Much higher quality of obtained materials. Significant simplification of the technological chain
Drying of wood 72 hours Estonia, Russia, Uzbekistan, Germany 3 hours 30 min More than 20 times / Much higher quality of obtained materials. Significant simplification of the technological chain
Drying of porcelain 24 hour / 1 hour Germany, Uzbekistan - 20-25 / much higher quality, simplification of technological chain
Drying of raw cotton 30 min / 1 min Total energy consumption is reduced by 10 or even more times. At the same time growth and development take place, as well as sterilization. Crop yield increases on average 150 kg/ha
Drying of fruit pastes of special products and food 1-6 hour / 7 min Germany, Uzbekistan 8-50. Significantly higher quality of the obtained target products. Certain products can only be obtained by our method. At the same time sterilization of products occurs
Fixation and heat treatment of molds 12-14 hours / 5-12 min Germany 50 kW / 3kW More than 1000 / Significantly higher quality and much more simplified technology
Drying of polyamide 15-25 hour / 3 hour Uzbekistan, Russia - 5-8. Significantly higher quality and much more simplified technology
Baking of bakery products 45-100 min / 5-15min Uzbekistan, Germany, Russia 36 kW / 9 kW 30-40. Significantly higher quality and much more simplified technology
Cooking of poultry, meat, fish and other 30-60 min / 5-15 min Uzbekistan, Russia, Germany, USA 2,2 kW / 1 kW 6-10. Significantly higher quality of the obtained target products. Much more simplified technology. At the same time deep sterilization
Sterilization 60-240 min / 5-15min Uzbekistan, USA, Singapore, Germany, Russia, Kirgizstan 3-20 kW / 0,1-0,15 kW Over 300. Significantly higher quality of the instruments after sterilization, simplified process
Low temperature sterilization 60-80 C / No analogy. Uzbekistan, USA, Singapore, Germany 0,1-0,2 (kW • hour)/kg No analogy
Drying of walls 6-12 days / 1-2 days Germany 3-6 kW / 0,5 kW Over 30. Significantly higher quality, there is no spoilage of cables, easy to use technology, total liquidation of mold and fungi
Heating of water of food, etc. in a dish covered with a ceramic layer Up to 2 times - Up to 2 times
Distinctive features of impact process to the various objects using functional ceramics is [10].
1. There is no thermal agent (hot air, steam, etc.), which takes away a significant part of the energy, which determines the low efficiency of traditional methods of influence.
2. Materials based on functional ceramics make it possible to convert a wide spectrum of primary energy source into a relatively narrow one within a given range.
3. An optimal wavelength can be chosen for a specific task. For example, in drying devices, such wavelength is chosen that the solvent absorbs this energy substantially higher than the target substance. This allows for careful and efficient drying of various objects. For baking, on the contrary, the products must absorb a lot of energy relative to the liquid. In addition, it is necessary to carry out photochemical reactions of protein digestion
to amino acids, starch to maltose, fat to fatty acids, etc. all this allows to receive high quality products, completely sterile and with minimal energy consumption.
4. Time parameters of pulsed IR radiation are optimized [5]. For example, sterilization of a medical instrument requires a high speed of the rising edge of the pulse, which leads to a momentary transformation of the water contained in any microorganism into vapor. As a result, bacteria, fungi, etc., «explode» from within. Due to this phenomenon, the tool corrosion centers are restored and the medical tool has a better surface than the new working surface after processing in such a sterilizer. In the autoclaves, intensive corrosion of the instrument with steam is observed and after several cycles of sterilization the tool becomes unusable.
In support of the above, we can give an example of optimization of the parameters of functional ceramics for drying walls [4]. If the first models of drying system created in 2003 consumed 1300 W at 1200 x 600 mm2 working area and dried the wall in 12 hours at a depth of 250 mm, optimization of the spectral range and parameters of the generated pulsed radiation allowed obtaining the same performance parameters at a power of not more than 500 W (actually the average power consumption was 375 W).
Despite the abundance and diversity of helio-technical installations proposed for use, only solar-thermal-energy and semiconductor photoconverters industrial production has been carried out. Due to the high cost, the scale of their production and scope of application remains limited. Therefore, the search for and development of efficient, low-cost low-potential solar plants suitable for a wide range of consumers are relevant to the current tasks of solar engineering.
A special polymer film containing 0.5-2.5% of ultradisperse powder of impulse ceramics has been developed. Comparative tests were conducted on the use of this film for drying processes, greenhouse farms, and temperature stabilization. As a control, the same film without ceramics was used. The original film itself is capable of converting UV radiation into visible light. In the films intended for greenhouses, the short-wavelength part of the spectrum is transformed by functional ceramics at 620-680 nm, which not only promotes high-efficiency photosynthesis, but also activates phytochrome. This allows to accelerate the development of plants, and also increases its resistance to adverse factors [28, 47]. The film with functional ceramics, in addition, is capable of generating IR pulses in a given spectral range [2, 4, 13, 14, 21-23, 29-31, 32-34, 43].
As an example of the results of investigation of temperature characteristics for a three-layer composite cascade - first layer is a polyethylene film with additives, converting the ultraviolet to visible range. This allows not only to more efficiently use the energy of sunlight, but also protects the film itself from photodestruction, which significantly extends its service life. The second layer is a frame of the same film to increase mechanical strength; the third, lower layer contains functional ceramics with nanostructures. The total content of ceramics in the composite is 2.5% (by mass) relative to polyethylene. Functional ceramics added to the third layer absorbs solar energy in a wide range and converts it into infrared radiation with a maximum of 9.7-10 microns. Given that
T = 2898/Wavelength corresponds, approximately, 290-300 K (17-270C).
As follows from the data in Fig. 1, at first a higher temperature is observed under the composite film; at a temperature of 15 °C there is an inflection; at an ambient temperature of 25-270 °C, the temperatures below the composite film and the reference film are equalized, and with a further increase in the ambient temperature, a lower temperature is observed under the composite film.
Fig. 1. Temperature difference T in chambers from a pure polyethylene film and a three-layer composite, depending on the ambient temperature.
The proposed three-layer composite with cascade transformation based on oxides of iron, chromium, calcium, magnesium, copper and polyethylene film significantly increases the process of solar energy transfer, and in comparison with conventional film has the following advantages.
1. Has a certain degree of ability to stabilize the temperature.
2. Allows more efficient use of solar energy when growing plants under a film.
3. Its effectiveness in temperature in the chamber is higher compared to conventional film, which is especially important, in a cloudy weather.
4. The composite, unlike a conventional polyethylene film, does not mist over, as it heats up to higher temperatures under the influence of solar energy, which makes it difficult to condense moisture on it.
5. It has good throughput of the red part of the spectrum, necessary for photosynthesis of plants.
6. Compared to a single-layer composite on the same basis, it is more effective in increasing the temperature in the chamber, and also significantly preserves the temperature in the chamber volume after sunset.
7. Allows to use ultraviolet part of a spectrum that simultaneously increases service life of a composite film.
8. The maximum transmission of radiation in the visible range is in the range of 620-700 nm, which facilitates the transition of plant phytochrome to an active form, and rehabilitation processes go much faster.
This opens up broad prospects for the practical use of a three-layer composite with cascade transformation in greenhouses, water heaters, air heaters, etc.
An experimental study of some thermophysical and biologically activating properties of the produced prototypes of a film-ceramic composite in field conditions was carried out. For this purpose, two 300 m2 plots with metal arc-shaped skeletons with a radius of 2.5 m and a length of 60 m were selected in the greenhouse farm "Vody nihol umidi" in Fergana. After appropriate preparation, the frames were covered with films in two layers with an air gap of 10 cm layer on the first frame consisted
of a composite film with a ceramics content of 5 wt. % (Film number 1), and on the second frame - a similar film with ceramics in
1.5 wt. % (Film No. 2). A single-layer polyethylene film with a thickness of 30 |im was used for the top layer. Both greenhouse rooms were not heated.
Tomato seedlings were landed on March 15, 2015 under film No 1 and on March 22 under film No 2. In the evening of March 27 and at night there was a strong hurricane with a wind speed of 20-25 m/s and the weather deteriorated until night frosts. The film No 2 was torn off from both ends at 5 and 15 meters, respectively, together with the metal wires holding them.
It was possible to strengthen the film only from one end (5 m), and the second end (15 m) remained under the open sky, because on March 31, snow fell and consisted 40 cm thickness. The temperature dropped to -8 °C at night, and in afternoon of April 1 temperature stayed at minus degree. On the morning of April 2, it was found out that the seedlings under Film No 1 were completely preserved; temperature was constantly higher than +5 °C there. Seedlings under Film No 2-5 m close to the open end have frozen and perished, and the rest were preserved as seedlings under the tightly closed Film No 1. This was a serious test of the composite film on the ability to keep heat in cloudy weather and at night, and even with one open end of the greenhouse. In the control greenhouse under the two-layered shelter of regular glass and conventional polyethylene film and using partial additional heating, seedling losses were about 50%.
Further comparative observations in April and May 2015 showed that the rate of growth of seedlings under composite films is almost twice higher than under regular glass. The stems and leaves of each seedling were large and strong. The flowering period decreased 1.3 times. The number of flowers on each tier was not less than 5-8 instead of 2-5. At night, under film No 1, the temperature was 6-8 °C higher, and under film No 2 -at 8-10 °C than the outside temperature. In the afternoon, depending on the degree of solar radiation, these indicators were 15-20 °C and 17-25 °C. On the composite films the temperature was always above the outside temperature at night. At external temperatures below 20 °C, fine droplets with a diameter of 1-3 mm were observed on the inner surface of the composite films, and on the film No 2 the droplet size did not exceed 2 mm irrespective of the dew point and humidity under the film.
An active ceramic additive (AKA) has been developed to lubricate rubbing metal-to-metal pairs in order to reduce the coefficient of friction, surface restoration, reduce energy consumption and increase the working life [17, 20, 37, 42].
The principle of AKA operation is based on the following processes.
1. The inhomogeneities and cavities present on the initial surface of the rubbing metal-metal pairs are filled with needle-shaped nanocomponents based on functional ceramics.
2. The surfaces are smoothed out, the cavities are partially filled with functional ceramics. When the rubbing pairs move relative to one another, the «needles» break off.
3. Nanocarbon balls fill the space between the needle structures embedded in the metal. Nanocarbon balls are also introduced to improve thermal conductivity in order to eliminate the possible overheating for some mechanical systems. The catalyst forms on the metal surface nanolayers from carbides, nitrides, oxynitrides, and others.
4. The rubbing surfaces are smoothed out, the micro-hardness of the working surface rises approximately 10 times, compared to the original metal. In particular, the microhardness of aluminum oxynitride is 4 times higher than microhardness of the glass. This leads to the fact that the stability of the system to abrasion increases significantly, the gaps between the rubbing pairs are equalized. As a result of all these changes, friction is greatly reduced.
5. Nanocomponents are introduced on the basis of functional ceramics with a phase different from those synthesized on friction surfaces. These phases are «not wetted» with each other, as a result the surface «floating» relative to each other, which makes it possible to further reduce friction and resistance to movement.
Preliminary results show that special additives based on functional ceramics synthesized on BSF in lubricating and cooling oils, creating a high-strength wear-resistant ceramic layer on the metal surface, having a high microhardness, low coefficient of friction, which protects against adverse effects, allows restoring their geometric dimensions, reduce energy consumption by reducing the work to overcome friction, as well as the level of vibration and noise.
On the basis of the electromechanical service of the Central Expert-Analytical Laboratory of OJSC Almalyk MMC, a new active ceramic additive (AKA) was tested.
Ventilation systems with great wear consume significantly - by 13-14%. The maximum energy saving value for the new system is 12.5%, while for the previously used value it is at the level of 20%. This is due, first of all, to some restoration of geometric dimensions, and also because the microhardness of the ceramic is substantially higher than the microhardness of the metal, which provides less friction
As a pilot installation, a water pump of grade 10KU7x2 with an electric motor of 250 kW and a capacity of 250 m3/h was used. At the same time, the level of vertical and horizontal vibrations decreased by more than 2 orders of magnitude, although the amount of AKA-1 introduced into the grease was only 0.1%.
Functional ceramics for drying paints, polymerization of high-molecular compounds and rubber vulcanization have been developed [5, 10]. Over the past two years, the following companies have tested the functional ceramics:
• Automotive industry: AUDI, BMW, DAIMLER, FORD, SKODA, OPEL, VOLKSWAGEN;
• trucks and buses: MAN, DAIMLER;
• Mechanical engineering: RIPPERT, VENJAKOB, OBRICHT, BÜRKLE;
• Train station wagon: SIEMENS, Waggonbau Niesky;
• Aircraft: AIRBUS;
• Shipbuilding: Meyer Werft;
• Wind turbines: ENERCON;
• the rubber industry: CONTINENTAL;
• Plastics: KRONES, AIRBUS, KIEFEL, BRÜCKNER, FRIMO, TAIYO EUROPE, RENOLIT SE.
The above-mentioned first 25 companies recognized the advantages of IR.C technology on the basis of materials developed by Professor Rakhimov D2 and P2.
Standard devices that allow these processes to be implemented with high quality of the final product are based on the use of ultraviolet radiation. Objects designed for painting or applying polymers must be thoroughly degreased.
The principle of action of functional ceramics is based on the fact that it generates two consecutive pulses. The first
pulse lasts about 10 microseconds, with an estimated energy density of 320 W/cm2 and promotes the formation of free radicals, including fats and oils on the surface of the object, which give rise to the growth of the polymer chain. The second pulse promotes chain growth. Unlike ultraviolet radiation, the polymer chains that have already formed are not torn. In practice, they all have the same length, which can not be achieved in any other way. In this case, a coating with high adhesion to the surface of the object is formed. Neither rust nor oil interfere with the process. Even with repeated bending of objects with the coating thus obtained, it does not peel off from the object and no cracks appear on the coating itself. The application of this method saves time, since the process lasts only 1-5 minutes, against 2 hours for the prototype. In addition, according to the usual technology, objects to be painted are placed in special furnaces with a temperature of 200-220 °C. According to the proposed technology, they are simply irradiated by infrared emitters based on functional ceramics. Such energy- and labor-consuming operations as deep degreasing and phosphating in special baths are eliminated.
This allows you to pre-paint, for example, a sheet of metal, and then make elements of complex shape from it [4, 10].
As is known, with increasing temperature, complex compounds are destroyed, and the coordination number decreases sharply with increasing temperature or under the influence of ordinary infrared radiation. Studies carried out using IR radiation generated by functional ceramics showed that if the maximum coordination number was 4, then under this influence the amount of ligands it increases to 100 or more. Thus, the high rising edge of the IR pulse activates the ligands, creating short-
lived radicals that recombine, and this time tightly surrounding the metal ion [3, 36].
Due to infrared radiation with a high pulse rise front, it is possible to obtain a system of gadolinium compounds surrounded by 100 or more molecules containing boron 10.
In addition to the above, the use of pulsed radiation also makes it possible to find new technological solutions for various applications. In particular, the technology was developed and production of an active calcium preparation in which each calcium ion is surrounded by a shell of 100 or more water molecules was established. Due to this, calcium will be digested with the speed that is required for normal functioning of a living organism [3].
The main raw material for the production of alumina at present are bauxites (A12O3 > 50%). However, in Uzbekistan, aluminum containing raw materials are secondary kaolins extracted from overburden mining operations. Each year, not less than 10 million tons of secondary kaolin is stored (A1203 ~ 22 content). In these conditions, the creation of alumina production in Uzbekistan is more important than ever.
It was shown that the use of pulsed IR converters in the processes of calcining, drying, dehydration, pyrolysis and other technological operations makes it possible to increase the efficiency of existing technologies several times. With regard to the issues of obtaining alumina from the Angren secondary kaolins by the nitric acid method, the use of pulsed IR converters at the most energy-intensive stages - the opening of the mineral (dehydration), the decomposition of aluminum nitrate, calcination of alumina, can reduce energy consumption by dozens of times. The results of the studies are given in Table 2.
Table 2
Nitric acid leachin secondary kaolin enriched
Time of IR formation, h Acid consentra-tion, % Leach temperature, °C Solid:Liquid Leach time, h Extraction of Al2O3, % Output of filter cake, % Note
Control 56,04 33 1:2 1 0,20 94,58
56,04 60-84 1:2 2 0,33 91,82
35,16 33 1:3 1 0,20 93,80
35,16 60-84 1:3 2 0,53 96,07
1 56,04 33 42,74 81,29 Stoichiometry
2 56,04 33 1:3 2 67,24 84,88 Stoichiometry
56,04 60-84 1:4 2 80,42 66,92 Surplice HNO3 8%
4 35,16 33 1:4 2 82,26 64,97 Surplice HNO3 8%
4 86-87 1:4 6 99,57 65,03 55,45% H2SO4 -total extraction
As follows from the data presented, pulsed IR converters [5] allow to completely recover alumina with minimal energy costs.
Special characteristics of the design of isothermal furnaces. As is known, the temperature regime is of decisive importance for many technological processes. In this regard, it is necessary to maintain the maximum possible temperature accuracy throughout the furnace. Ovens, commonly used in the synthesis or annealing of ceramic materials, have an uneven temperature field of 50-100 degrees and higher
at 10 000 °C. The use of electronic devices with appropriate sensors allows the temperature to be kept within permissible limits only in the sensor area, but does not solve the problem of obtaining an isothermal chamber. In this connection, the analysis of the factors allowing to achieve the desired result was made and the ways of solving this problem were suggested, which found application not only in specialized furnaces, but also in many devices where high homogeneity of the temperature in the working volume is required [17, 18] .
Heating elements have:
• the positive dependence of the resistivity on temperature;
• negative dependence;
• the specific resistance of which is practically independent of temperature.
The higher the dependence of the resistivity on temperature, the more uniform the temperature in the volume can be obtained. Suppose there is a heater whose resistivity does not depend on temperature. Such materials include constantan, nichrome and some brands, etc.
Taking into account that hot air rises as the heat is heated, the temperature in the upper part of the chamber will significantly exceed the temperature in its lower part and this difference increases with increasing temperature. On such heaters it is very difficult to obtain uniformity of temperature below 50-100 degrees at 10 000 °C.
When heaters with a positive temperature-dependent resistance function are used, it all depends on how the heaters are connected to the power supply system - in parallel or in series.
In the case of a parallel connection, in a zone with a higher temperature, the resistance of the heater will be higher than the resistance of the heater in the zone with a lower temperature. Thus, the power allocated to the «hot» heater will be halved, compared to the «cold» heater, and this will continue until the temperatures in the zones of the heaters are aligned.
The steeper the dependence of the resistivity on temperature, the more accurate will be the alignment of the temperature field in the zones of location of the respective heaters. In other words, the heaters themselves in this case are temperature sensors and simultaneously power ratio controllers for the whole group of heaters.
If the temperature dependence of the resistivity is negative, only a series connection will lead to the possibility of obtaining a uniform temperature field in the furnace volume.
Certain standard requirements are imposed on lining materials. They are selected according to the following criteria:
• temperature resistance;
• heat resistance;
• chemical resistance;
• minimum thermal conductivity;
• maximum thermal resistance;
• satisfactory mechanical characteristics;
• high electrical insulating properties over a wide temperature range.
For isothermal furnaces, special liners have been developed which, in addition to the above conditions, also carry additional linings. Lining is made of a material with a phase transition without a volume or allowable volume effect in the required temperature range. This makes it possible not only to increase the uniformity of the temperature distribution over the volume, but also to store energy - the phase transition absorbs energy and the temperature rises slightly.
For high-tech furnaces, a multi-layer lining of various materials has been developed - in each zone a material with a characteristic value of the phase transition was used. If the material properties change as the lining is formed from the inner side to the outer one, then the phase transition temperatures are reduced with each subsequent layer. This allowed us to set a temperature gradient that not only ensures the operation of the furnace in an economical mode with a uniform temperature distribution in the working volume, but also reduces the temperature of the shell, significantly reduces
the thickness of the liner, and also the total mass of the furnace. A number of ceramic heaters have been developed, which have shown their effectiveness, high mechanical strength, heat resistance and the possibility of heating at much higher speeds.
The solution to this problem was possible as a result of the creation of multilayer structures. The internal part of the heater is made of a heat-resistant and mechanically strong material, for example, aluminum oxide, calcium zirconate, etc. The outer part is an electrically conductive ceramics based on RE chromite. Current leads are made of materials based on chromites of rare earth elements, but they are doped with additives that give increased electrical conductivity.
Fig. 2. High-temperature ceramic heaters and thermocouple for operation in the air up to 1800-20 000 °C.
The above principles allow the creation of compact, highly efficient and economical ovens for various purposes with an isothermal working chamber. In addition to the above, the same principles can be used in the development of grills, dryers, thermostats, incubators and for other cases where strict maintenance of temperature in a given volume is required.
Functional ceramics for medicine. Ceramic spectrum converters that generate infrared radiation with selective effect only on the pathogenic microflora, pathologically altered organs and tissues that allow to normalize metabolic processes at the molecular level and eliminate the cause of the disease, and not only its symptoms have been developed.
4 series of ceramic materials - K, R, G, Z emitters in a range from 8 to 50 microns are developed. They can generate continuous, pulsed infrared radiation or emit energy in a complex time sequence [38, 40, 41].
The mechanism of action of the emitter series K. Ceramic materials of the K series make it possible to obtain radiation corresponding to the spectral range of human radiation, but they are divided into the following types:
• KS - used - for preventive purposes;
• KL - it is recommended to use with a decreased reaction of the sympathoadrenal system;
• KH - It is recommended to use with a lower response of the parasympathetic vegetative system;
• KB - to accelerate the regeneration of bone tissue.
Clinical (in patients with psoriasis, oncological diseases, bronchitis, etc.), studies have shown that all these emitters have
an immunocorrective effect and contribute to the restoration of immunity.
Emitters of the Z series. Depending on the strength of the action, the Z-series emitters are divided into 4 types and in order of increasing effect on the pathological tissues are arranged as follows: ZB ^ ZC ^ AK ^ AV.
The conducted researches showed that the inclusion of these radiators in the complex of prevention allowed to reduce the incidence of adhesion process in 2 times. They are also very effective for angiopathy.
Emitter series R. The basis of the pathogenesis of many diseases is an excess of free radicals. Existing methods of therapy can not always sufficiently contribute to their elimination.
The mechanism of action of the radiator RC (in particular, anti-oncological) is to neutralize the active radical, for example, an oncological cell, which contributed to its infinite division and growth. The RC emitter emits two consecutive pulses (Fig. 3).
Duration, ms
Fig. 3. The shape of the pulse, emitted by the RC emitter
The first pulse lasts about 10 microseconds, with an estimated power of 320 watts per square centimeter and helps normalize the level of free radicals. This mechanism is based on its use in the treatment of diseases of the cardiovascular system, oncological diseases. Its use on the tumor region reduces the superoxide radical content to the normal level. The R emitter series has been successfully used in the treatment of viral diseases: influenza, mumps, herpes infection. In addition, the use of the R emitter is possible in the treatment of diabetes mellitus, myocardial infarction, where free radicals and viruses play an important role in the pathogenesis of disease development. The use of the RC radiator in the treatment of malignant tumors showed that 34% of patients had an improvement in general condition; 58% of patients showed improvement in symptoms associated with the presence of a tumor; Significant changes in the clinical manifestations of the tumor process (such as a reduction in pain associated with the appearance of metastases) were noted in 10.3% and in 24% there was a decrease in metastatic bone pain.
The GI emitter is based on the materials used for the RC emitter. The main material is mullite, which is obtained using a special technology using BSF and has a transmission bandwidth of up to 25 microns. The share of RC materials in the GI material is 0.5%. As a result of carried out experiments in rats it was shown that the GI series emitters also positively influences the state of lipid peroxidation processes, the level of enzymes of the monooxygenase system. The use of this emitter contributes to the restoration of the reproductive function of testes, has a pronounced anti-inflammatory effect in children with mechanical trauma several times faster (in comparison with traditional treatment), local sensitivity of tissues was restored, positively influencing the regeneration processes in purulent surgical infection. Application in the postsurgeon period in patients with liver echinococcosis allowed to avoid wound suppuration, accelerated closure of residual cavities and promoted wound healing by primary tension.
As a result of scientific and applied research, the technology of synthesis of materials with a set of specified properties on the BSF has been introduced into production.
Based on these materials developed.
High-temperature durable and reliable heaters for operation in air and oxidizing atmosphere up to 20 000 °C, lining, and also furnaces on their basis.
Highly efficient drying devices using ceramic emitters for various objects, allowing not only to save energy and time, but also to receive high quality products, unattainable by conventional drying methods for which international patents and certificates are obtained. In total, more than 25 models for various objects have been developed [1, 47]. For the devices for drying the walls after flooding, we received the GRAND PRIX of Germany for the best development of 2003 «Einfach Genial» -«Simply Brilliant».
Highly efficient devices for baking and cooking, for which international patents and certificates have been obtained. At the forum of bakers (Munich, 2006) the baking method is recognized as the best. In total, more than 10 models for different objects have been developed.
Highly effective sterilization devices for which international patents and certificates have been obtained. In total, more than 10 models have been developed for sterilizing various objects.
Highly effective therapeutic devices based on functional ceramics, for which international patents and certificates have been obtained. In total, more than 20 types of medical treatment plants for various purposes have been developed and introduced into production.
Developments are tested and implemented in Uzbekistan, Russia, Belarus, Kazakhstan, Georgia, Estonia, USA, Singapore, Malaysia, Germany, South Korea, Vietnam, Turkey, Switzerland.
Resonance therapy by the method of R. Rakhimov is introduced into the training program:
• Tashkent Institute of Pharmacology since 1998;
• Institute of the advanced training of physicians of the Ministry of Health of the Republic of Uzbekistan - since 1999;
• Institute of advance training of physicians of the Russian Federation - since 2003;
• Russian Peoples' Friendship University - since 2003.
Published more than 300 scientific articles, 11 monographs, more than 80 inventions.
References
Bibliography
1. Rakhimov R.Kh., Ermakov V.P, Rakhimov M.R., Latipov R.N. Method of drying raw cotton IAP 04881 / Decision on the grant of patent No 3263, dated March 28, 2014.
2. Rakhimov R.Kh., Ermakov V.P, Rakhimov M.R. Film-ceramic composite for solar dryers IAP 2011 0375 (22) 24.08.2011.
3. Rakhimov R.Kh., Ermakov V.P, Method for the preparation of active calcium citrate. The decision to grant a patent on May 13, 2014.
Scientific publications
4. Rachimov R. Kh., Ermakov V.P., John P., Rachimov M.R. Anwendung funktioneller keramiken für technologien des trocknens mit impulsinfrarot. Freiberg research folders // Journal of Mining Academy. Freiberger Forschungshefte. Published on 06/02/194. Pp. 1-44.
5. Rachimov R. Kh. Mechanismus zur Erzeugung von Infrerotimpulsen mit funktionalen Keramiken. Freiberg research folders // Journal of Mining Academy. Freiberger Forschungshefte, 2014, March. Pp. 1-13.
6. Rakhimov R.Kh. Principles of the development of materials with a set of prescribed properties in the synthesis of BSP // Conference materials dedicated to the 90th anniversary of SAAzimov. Tashkent, 2004. Pp. 176-178.
7. Rakhimov R.Kh., Saidov M.S. Development of ceramic coatings and application of their infrared radiation // Proceedings of the International Conference «Renewable Energy Sources and Solar Materials Science». Tashkent, 2005. Pp. 204-211.
8. Rakhimov R.Kh., Ermakov V.P. Basics of designing drying plants using functional ceramics. Part I: On the criteria for selecting functional ceramics for drying processes // Heliotechnics, 2010. № 4. Pp. 70-77.
9. Rakhimov R.Kh., Ermakov V.P., Rakhimov M.R. Features of drying bioobjects using functional ceramics synthesized on the Big Solar Stove // Heliotechnics, 2011. № 1. Pp. 67-72.
10. Rakhimov R.Kh., Ermakov V.P. Functional ceramics: monograph // Farghona, 2007. 328 p.
11. Rakhimov R.Kh. On the role of the convective factor in radiation drying // Heliotechnics, 2010. № 4. Pp. 77-79.
12. Rakhimov R.Kh., Ermakov V.P., Rakhimov M.R. Features of drying bioobjects using functional ceramics synthesized in the Big Solar Furnace: abstracts // International Scientific Conference «Modern Scientific and Technical Solutions for the Efficient Use of Renewable Energy Sources». Tashkent, 14-15 April, 2011. Pp. 165-168.
13. Ermakov V.P., Rakhimov M.R. Energy transfer efficiency of an oxide-based ceramic ceramic photovoltaic converter // Applied Solar Energy, September 01, 2009. 45. P. 200-202. http://www. springerlink.com/content / ug35v5188814u5w7.
14. Rakhimov R.Kh., Saidov M.S. Pottery with an energy barrier and two-pulse temperature radiation // Heliotechnics, 2002. No 3. Pp. 71-74.
15. Rakhimov R.Kh. The mechanism of generation of infrared pulses by functional ceramics // Scientific and technical journal «Chemistry and Chemical Technology», 2013. № 4. Pp. 2-9.
16. Rakhimov R.Kh., Ermakov V.P., Rakhimov M.R. Drying, carried out by pulsed radiation, generated by functional ceramics // Scientific and technical journal «Chemistry and Chemical Technology», 2014. No 1. Pp. 52-57.
17. Rakhimov R.Kh., Yuldashkhodjaev A.I., Ermakov V.P., Rakhimov M.R., Latipov R.N. On the possibility of using ceramic materials synthesized in a large solar furnace in energy and resource saving // Scientific and technical journal «Chemistry and Chemical Technology», 2014. № 3. Pp. 2-6.
18. Rakhimov R.Kh., Ermakov V.P., Rakhimov M.R., Latipov R.N. Features of the design of isothermal furnaces // Republic of ilmium-technology anzhumani materialari «Condensatlangan muhitlar fizikasi va materialyunshunoslining dolzarb masalalari», yil 14-15 May 2014. Farghona, 2-shuba. Jarim Utkazgichlar material slaughter. Pp. 77-79.
19. Mosimov M., Rahimov R., Onarulov K., Raumatov M. The past has come to be the ripeness of the Masulularynarini of the Narrative of the infrared Nourishing of the Hands // Republic of ilmium-technology anzhumani materialari «Condensatlangan muhitlar fizikasi va materialyunshunoslining dolzarb masalalari»,
yil 14-15 May 2014. Farghona, 2-shuba. Jarim Utkazgichlar material slaughter. Pp. 142-144.
20. Rakhimov R.Kh., Yuldashkhodjaev A.I., Ermakov V.P., Rakhimov M.R., Latipov R.N. Possibilities of using ceramic materials synthesized in a large solar furnace in energy and resource saving // Republic of ilmium-technology anzhumani materialari «Condensatlangan muhitlar fizikasi va materialyunshunoslining dolzarb masalalari», yil 14-15 May 2014. Farghona, 2-shuba. Jarim Utkazgichlar material slaughter. Pp. 162-163.
21. Rakhimov R.Kh., Ermakov V.P., Rakhimov M.R. Solar air heater with a three-layered composite film // Applied Solar Energy, 1 June 2010. № 46. Pp. 122-124. http://www.springerlink.com/ content/98x1773wk4435656.
22. Rakhimov R.Kh., Ermakov V.P., Rakhimov M.R. Solar heater incorporating polythene film-ceramics composite material on the basis of iron oxide // Applied Solar Energy, 1 March 2010. № 46. Pp. 56-59. http://www.springerlink.com/content/ 44748w3j84826777.
23. Rakhimov R.Kh., Ermakov V.P., Saidov M.S., Rakhimov M.R. Study of the energy transfer efficiency of a composite photo-heat-photon converter based on iron oxide / Int. Conf. dedicated to the 80th birthday of Academician Saidov MS «Fundamental and Applied Problems of Physics», 24-25 November 2010. Tashkent. P. 138.
24. Rakhimov R.Kh. On the choice of time, power and spectral parameters of radiation of functional ceramics for drying processes / Int. Conf. dedicated to the 80th birthday of Academician Saidov MS «Fundamental and Applied Problems of Physics», 24-25 November 2010, Tashkent. P. 132.
25. Rakhimov R.Kh. Synthesis of high-temperature oxide materials of a given stoichiometric composition on the BSP // Materials of the international conference dedicated to the 15th anniversary of Uzbekistan's independence «Fundamental and Applied Problems of Physics», 26-27 October 2006. Tashkent. Pp. 114-116.
26. Rakhimov R.Kh., Ermakov V.P. Features of the design of cabinet drying with the use of functional ceramics as an active element // Materials of the international conference dedicated to the 15th anniversary of Uzbekistan's independence «Fundamental and Applied Problems of Physics», 26-27 October 2006. Tashkent. Pp. 368-370.
27. Rakhimov R.Kh. Mathematical models of light pulse stimulation of seeds by laser and concentrated solar radiation: abstracts // International Scientific Conference «Modern Scientific and Technical Solutions for the Efficient Use of Renewable Energy Sources», 14-15 April 2011. Tashkent. Pp. 169-173.
28. Rakhimov R.Kh., Ermakov V.P., Rakhimov M.R. Features of drying raw cotton using functional ceramics, synthesized on the Big Solar Stove // Heliotechnics, 2011. № 1. Pp. 67-72.
29. Rakhimov R.Kh., Ermakov V.P., Rakhimov M.R. Solar air heater with the use of a composite polyethylene film-ceramics based on iron oxide // Heliotechnika, 2010. № 1. Pp. 59-62.
30. Rakhimov R.Kh., Ermakov V.P., John P. Application of functional ceramics in devices for baking and cooking // Materials of the international conference dedicated to the 15th anniversary of Uzbekistan's independence «Fundamental and Applied Problems of Physics», 26-27 October 2006. Tashkent. Pp. 371-372.
31. Rakhimov R.Kh., Ermakov P.V., Rakhimov M.R. Solar air heater with a three-layer composite film // Heliotechnika, 2010. № 2. Pp. 43-46.
32. Rakhimov R.Kh., Yuldashkhodzhaev A.I., Ermakov V.P. Possibilities of using ceramic materials synthesized in a large solar furnace in energy and resource saving // II International Conference on Optical and Photoelectric Phenomena in Semiconductor Micro- and Nanostructures, 8-9 September 2011. Fergana. Pp. 312-314.
33. Rakhimov R.Kh., Ermakov V.P., Rakhimov M.R., Latipov R.N. Film-ceramic composite with active nanostructures for the conversion of solar energy // II International Conference on Optical and Photoelectric Phenomena in Semiconductor Micro- and Nanostructures, 8-9 September 2011. Fergana. Pp. 104-105.
34. Rakhimov R.Kh., Ermakov V.P., Rakhimov M.R., Latipov R.N., Saimbetov A. Possibilities of functional ceramics in increasing the efficiency of silicon solar cells // II International Conference on Optical and Photoelectric Phenomena in Semiconductor Micro- and Nanostructures, 8-9 September 2011. Fergana. Pp. 301-302.
35. Rakhimov R.Kh. and others. Peculiarities of the influence of pulsed electromagnetic radiation generated by functional ceramics on precessive technological processes // II International Conference on Optical and Photoelectric Phenomena in Semiconductor Micro-and Nanostructures, 8-9 September 2011. Fergana. Pp. 314-316.
36. Rakhimov R.Kh., Muminov R.A., Ryskiev T.T. The possibility of using functional ceramics synthesized on BSP for the synthesis technology of complex compounds // Heliotechnics, 2012. № 1. Pp. 54-58.
37. Rakhimov R.Kh., Yuldashkhodjaev A.I., Ermakov V.P. Functional ceramics for reducing friction in the system of rubbing metal-metal pairs // Heliotechnics, 2012. № 2. Pp. 74-77.
38. Rakhimov R.Kh. Ceramic materials and their application: monograph. Part 1. Tashkent: Yangi asr Avlodi, 2000. 160 s.
39. Rakhimov R.Kh., Ermakov V.P. The effect of pulsed fields on elements with different valences // Proceedings of the International Conference «Renewable Energy Sources and Solar Materials Science», 2005. Tashkent. Pp. 217-219.
40. Rakhimov R.Kh. Ceramic materials and their application: monograph. Part 2. Tashkent: UzPHITI, 2003. 667 p.
41. Rakhimov R.Kh. Ceramic materials and their application: monograph. Part 3. Fargona, 2005. 174 p.
42. Rakhimov R.Kh., Yuldashkhodjaev A.I., Ermakov V.P. Possibilities of using ceramic materials synthesized in a large solar furnace in energy and resource saving // Engineering science, October 2011. № 6, Rubric: 05.00.00.
43. Rakhimov R.Kh. et al. Application of polymer-ceramic composite films in photovoltaics // Engineering science, October 2011. № 6, Rubric: 05.00.00.
44. Rakhimov R.Kh., Ermakov V.P., Rakhimov M.R. Film-ceramic composite for greenhouses // Engineering science, October 2011. № 6, Rubric: 05.00.00.
45. Rakhimov R.Kh., Ermakov V.P., Rakhimov M.R. Efficiency of drying with the use of metal-ceramic and film-ceramic photo-heat-photon converter // Engineering science, October 2011. № 6, Rubric: 05.00.00.
46. Rakhimov R.Kh., Tikhonova N.N. Long-range narrow-spectral infrared radiation is a new opportunity in the treatment of diseases // Medical sciences, October 2011. № 6, Rubric: 14.00.00.
47. Rakhimov R.Kh., Ermakov V.P., Rakhimov M.R. Features of drying cotton-sarca using functional ceramics, synthesized on a large solar furnace // Engineering science, October 2011. № 7, Rubric: 05.00.00.
48. Rakhimov R.Kh. Resource- and energy-saving technologies in the production of agricultural crops // Engineering science, October 2011. № 7, Rubric: 05.00.00.
49. Rakhimov R.Kh., Ermakov V.P., John P. Drying of industrial catalysts and wood with the use of functional ceramics // Engineering science, October 2011. № 7, Rubric: 05.00.00.
50. Rakhimov R.Kh. Principles of the development of materials with a set of specified properties // Modern technology and technology. http://technology.snauka.ru/2011/11/140.
51. Rakhimov R.Kh. Functional ceramics and areas of its application // This material is presented by the UNESCO Office, 2009. http://www. energy. econews.uz/index.php?option=com_conten t&view=article&id=47%3Aunesco-&catid=4%3A2009-02-15-12-30-01&Itemid=5
