[1] We have investigated the influence of continental lids on mantle convective stirring efficiency using numerical experiments and analytical theory at infinite Prandtl number with strong temperature dependence of viscosity. Differences between oceans and continents are accounted for by imposing heterogeneous surface boundary conditions for temperature and velocity. We measure the convective stirring efficiency using mixing times and Lyapunov exponent distribution. We quantify systematically the influence of the Rayleigh number, the horizontal extent of continental lids and the rheology on mantle convective stirring efficiency. The presence of continents increases the mantle temperature and therefore reduces mantle viscosity. This in turn leads to an increase of convective vigor and results in a drastic enhancement (3-6 fold, and possibly up two orders of magnitude increase) of mantle convective stirring efficiency.

The radiation resistance of epoxy compounds, solidified by crystalline hardening agents -metaphenylenediamine and phthalic anhydride -is investigated. It is shown that under conditions of γ irradiation (E = 1.33 MeV) the temperature of vitrification of the compounds depends on the dose (doses up to 1500 Mrad were investigated) and temperature 20-160°C, and the radiation gas release depends on the vitrification temperature and irradiation. It is shown that epoxy-phthalic anhydride compound is best as a matrix for immobilizing solid radioactive wastes at high temperatures (80-130°C). The experiments showed that the proposed compound can be recommended for immobilizing solid radioactive wastes.A great deal of attention is now being devoted to choosing the compounds for immobilizing radioactive wastes [1][2][3]. Epoxy compounds are promising materials for handling wastes, because such compounds possess high radiation resistance due to their content of aromatic groups [1]. The possibility of fixing radionuclides in reactor graphite by an epoxy oligomer, whose density was increased by heterocyclic aldehyde of the furan series with a filler and special-purpose additive, was demonstrated first in our country. The solidifying agents used for epoxy compounds are characterized by a crystalline and liquid aggregate state and radiation resistance. Solidifying agents such as polyethylene polyamine and polyamides are used, for example, in the immobilizing agent F and the Atomik compound, whose operational properties are described in [1]. The compounds of these solidifying agents are convenient to use because they do not require additional heating. However, the relatively low vitrification temperature (~60°C) gives rise to difficulties in using such compounds for immobilizing solid wastes, whose radiation heating exceeds 60°C. If the temperature of radiation heating exceeds 80°C, it has been suggested that compounds undergoing hot solidification be used, and metaphenylenediamine (a crystalline substance with a melting temperature of 63°C) and phthalic anhydride (a crystal substance with melting temperature 130°C) be used as the solidifying agent [4]. The wastes are solidified at temperatures not less than the melting temperature of the solidifying agent. Then the compound is in a low-viscous state and when solid wastes are immobilized it penetrates into the microcavities, forming a reliable matrix.The immobilizing agents for solid wastes must meet the following basic requirements: they must have high mechanical and adhesion strength, they must remain stable in water solutions, including solutions of acids and alkali, they must be in a glassy state under operating conditions, leaching of radionuclides should not exceed 10 -4 g/(cm 2 ·day), and the gas release should be minimal (not greater than 10 -8 -10 -9 cm 3 /(g·rad)). Under operating conditions, the deviation of the first four parameters should not decrease by more than 25%.The experiments showed that solidified epoxy compounds in a glassy state have high strength under comp...

The effect of dust properties, parameters and composition of gases for cleaning on the choice of synthetic filter materials for bag filters with pulsed regeneration is considered. Particular attention is devoted to cleaning high-temperature moist gases containing corrosive components. Recommendations are proposed for calculating the temperature of the acid dew point of gases being cleaned. Comparative characteristics are provided for synthetic materials produced overseas and used in gas filtration.One of the most efficient methods for cleaning industrial gas discharges from dust is filtration through cloth barriers. Of the numerous items of equipment operating on this principle, recently the most extensively used is bag filters with pulsed regeneration of the filtering cloth surface by compressed air. These filters are characterized by a high degree of capture due to the use of needle-punched filter materials, servicing simplicity as a result of the absence of moving parts (apart from the dust discharge system), compactness and correspondingly small area occupied.The operating reliability and efficiency of bag filters depends to a considerable extent on physicomechanical properties of the dust being captured (dispersed composition, abrasiveness, adhesiveness, hygroscopicity, electric properties of dust particles; tendency of dust particles towards coalescence, etc.), and also the main parameters of the gas stream being cleaned (temperature, moisture content, chemical composition).A careful study of production processes that are accompanied with emission of harmful substances; analysis of the qualitative and quantitative characteristics of the medium for cleaning in a bag filter; and the correct choice of synthetic filter materials for bag filters are all necessary conditions for achieving highly efficient and prolonged operation of this equipment.Recently in domestic practice of dust capture the most widely used filter materials are produced by well-known firms: Dupont (USA), Webron (Great Britain), BVF (Germany). Main Dust PropertiesDispersed composition. This is an original parameter in designing filtration equipment, that commences with a choice of specific gas flow (ratio of the volume of gas being cleaned in a unit time to the filtration surface area), expressed numerically as a rule by m 3 /(m 2 ·min), which corresponds to the gas filtration rate. The specific gas load should not exceed an optimum value, with which a sufficiently effective degree of cleaning and a not very high hydraulic resistance for the filter are provided.

Designs and characteristics are given for sleeve filters with explosion-protected design which have been developed by the NIIOGAZ.Various technologies give rise to dusty gas flows containing suspended explosive particles: metal melting, making organic products, and many chemical and petrochemical processes.Sleeve filters have become used as dust traps in recent years in connection with tightened specifications for performance in cleaning gases.For an explosion to occur, one needs a certain concentration of the explosive dust exceeding the lower flame propagation concentration (LFPC) [1]. When the sleeve filter is used as a dust trap, it is not possible to produce a dust content below the LFPC in the volume of the apparatus because on regenerating the filter surface the dust concentration varies widely.In addition to a dust concentration exceeding the LFPC, explosion requires an ignition source of adequate temperature and power, and also an appropriate oxygen concentration. However, it is very expensive to prevent explosion in sleeve filters when large gas volumes are to be treated. Therefore, to prevent explosion in a sleeve filter, one uses various designs: special valves, protective membranes, and so on.Safety membranes are most widely used at present in explosion-protection devices, which form an especially weakened part of the body of the sleeve filter with an exactly calculated failure pressure.Calculations on safety membranes involve determining the necessary area of the discharge hole, as well as the thickness and other geometrical parameters of the membrane on the basis of rupture at a given pressure.One calculates the area of the discharge hole, i.e., the membrane area, in accordance with RTM 6-28-009-90 [2], according to which the most hazardous situation is when the pressure in the body of the sleeve filter increases at the maximum rate.The amount of dust-gas mixture G a (kg/sec) formed in an accident can be related to the corresponding pressure rise rate by where M is the molecular mass of the gas in the apparatus in kg/mol (for suspensions in air, it is taken that M = 0.029, as for air); V is the internal volume of the sleeve filter body, including the volume occupied by the sleeves, in m 3 ; R is the universal gas constant, which is 8.314 J/(mol·K); T is the absolute temperature of the gas within the filter in K; and (dp/dt) max is the maximum rate of pressure rise in an explosion in time t (sec), MPa/sec. When one calculates the area of the discharge hole, one incorporates the condition for compensation of the discharge of the dust-gas mixture G a through the hole after the membrane ruptures, i.e., G ≥ G a , in which G is the flow rate per second through the hole, kg/sec.