-When preparing cement raw slurry, in order to regulate its aggregative stability and flowability, a coal-alkaline additive is used, which not only changes the surface properties of disperse particles, but also intensifies the portland cement clinker synthesis process. Adding of coal-alkaline reagent into the raw mix allows not only reducing the viscosity of the slurry and improving its fluidity, but also lowering the temperature of clay minerals dehydration and СаСО 3 decarbonization and the substances interaction processes in the solid phase proceed as a result at the temperature under 1250-1270 °С. Thermodynamic calculations have allowed theoretically confirming the efficiency of this additive's application. A considerable amount of the released heat in the temperature interval of 200-452 °°°°С intensifies the removal of the chemically bound water from clay minerals and contributes to the destruction of their crystalline lattices, which is eventually good for reducing the specific fuel consumption. Thermodynamic calculations have also confirmed the possibility of the formation process of clinker minerals at relatively low temperatures in the presence of the additive and allowed evaluating the role of certain components of the additive in this process. The calculation data of ∆G Т о indicate the increase of the system's stability when using coal-alkaline reagent.
The centrifugal-force method is considered for generating a filter material. The design is given for a dynamically regenerated filter, which uses a crankshaft operating with filter elements. The gas velocity pattern has been determined in narrow and wide gaps between a rotating blade and the surface of the filter.A method based on centrifugal forces is effective in regenerating filters [1], in which the dust particles are eliminated from the surface of a rotating filter element during ongoing gas filtration. A filter with continuous centrifugal regeneration usually has a framework structure of cylindrical or plate form, or else in the form of a star.Continuous filter rotation means that only small dust particles reach the surface of the cloth. The rotation speed should be such that the centrifugal force detaching the dust layer should be greater than the force of adhesion to the filter surface. The shortcomings of such a filter are as follows: cumbersome design, small throughput, and relatively large energy consumption.In the filtration of a finely divided aerosol, the main resistance is provided by the layer of deposit, and any method of continuously removing it from the baffle intensifies the process considerably. A filter has been designed that combines the advantages of centrifugal regeneration with the compactness of a planar filter element with an extended surface per unit volume [2].The filter (Fig. 1) has the body 1 with input collector 2 and outgoing tube 3, chambers for the clean gas 4 and contaminated gas 5, a bunker for the trapped dust 6, and filter elements 7. The body contains a crankshaft 8 (with blades 9), which has two bearings and is joined by a rigid clutch to an electric motor (not shown).The filter works as follows. The dusty gas enters the body through a collecting pipe, which distributes the flow evenly to each filter element. The blades rotate between the sections of filter elements. When the bladed shaft rotates, the largest particles move towards the body walls and are collected in the bunker.In this design, the layer structure is disrupted and the deposit is removed on account of ongoing turbulence in the narrow gap s (Fig. 1) between the rotating and fixed elements, on account of the continuous driving action by the velocity gradient in the dusty flow, their pulsations, and the action of the centrifugal force.In a dynamic filter, the filtration occurs largely through the baffle bearing particles of solid, and not through the continuously growing layer of deposit, so the filtration rate remains low throughout the process.Filter regeneration may be ongoing (by changing the shaft speed n, one can regulate the thickness of the dust layer on the elements and consequently the filter performance) or may be periodic (on the attainment of a certain pressure difference). The aerodynamic conditions allow one to conduct the filtration with an adjustable pressure difference across the filter baffle.
An approach to formulation of a process for tangential filtration of dust-gas flows is described. Schematic diagrams of structural solutions developed for the filters are discussed. Results are presented for aerodynamic characteristics of the filter for different positions of an adjustable baffle. Basic operational problems are analyzed. The efficiency of the regeneration process is evaluated.There are two methods of cleaning dust-gas flows by passage through a filter baffle plate. Dead-end (blind-pass) filtration, during which a cake of suspended material that accumulates in proportion to the volume of cleaned gas and dust concentration, is formed on a filter baffle plate (FBP) is one of the simplest and most widespread methods [1]. The increase in cake on the FBP is continuous; this involves an increase in pressure gradient, or reduction in gas flow, as a result of which it is necessary to remove this cake from the FBP.Cross-flow filtration, which is widely used in membrane technology and attaches increasing significance in gas cleaning, is another method of cleaning dust-gas flows [2]. Note that the term cross-flow is not entirely correct, since it does not fully correspond to the process in which a dust-contaminated gas flows parallel (and not at a right angle) to the FBP. The terms parallel filtration or tangential filtration would be more accurate. Absence of cake or negligible formation of trapped dust on the FBP is characteristic of cross-flow filtration. Particles deposited on the FBP are carried-off (withdrawn) by the flow of dust-contaminated gas. The cleaning efficiency of the gas flow increases with its increasing velocity.Tangential filters with a small motive force of a self-cleaning FBP are the filters that are most familiar and simplest in terms of design. A filter with flow-through pipes or chambers may serve as an example of the structural shape of these filters (Fig. 1).The filter functions in the following manner. A dust-contaminated gas is fed under a pressure gradient through pipe 1 into a dust-containing-gas chamber. On passing through FBP 8, the dispersion medium is cleaned of contaminants, delivered to a cleaned-gas chamber, and is then discharged from the vessel via pipe 7. As trapped dust is deposited on the external surface of the FBP, the resistance of the filter increases, and the latter must be cleaned -regenerated. At the moment of regeneration, adjustable baffle plate 3 is dropped to a lower position by means of transverse 5 and flexible inserts 2. Owing to an increase in the velocity of the flow, moreover, a tangential motive force, which contributes to removal of sediment from the surface of the FBP, develops.During the testing of such a filter, its aerodynamic characteristics were determined as a function of various positions of the adjustable baffle plate. A perforated metallic foil with 75-µm pores was used as the filter material. A dust-gas flow with a dust concentration of 3-5 g/m 3 was simulated in a fluidized-bed pulverized-coal feeder. Quartz dust with a lognormal par-
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