2,118 research outputs found
Development of limb volume measuring system
The mechanisms underlying the reductions in orthostatic tolerance associated with weightlessness are not well established. Contradictory results from measurements of leg volume changes suggest that altered venomotor tone and reduced blood flow may not be the only contributors to orthostatic intolerance. It is felt that a more accurate limb volume system which is insensitive to environmental factors will aid in better quantification of the hemodynamics of the leg. Of the varous limb volume techniques presently available, the ultrasonic limb volume system has proven to be the best choice. The system as described herein is free from environmental effects, safe, simple to operate and causes negligible radio frequency interference problems. The segmental ultrasonic ultrasonic plethysmograph is expected to provide a better measurement of limb volume change since it is based on cross-sectional area measurements
Apparatus for determining changes in limb volume
Measuring apparatus for determining changes in the volume of limbs or other boty extremities by determining the cross-sectional area of such limbs many comprise a transmitter including first and second transducers for positioning on the surface of the limb at a predetermined distance there between, and a receiver including a receiver crystal for positioning on the surface of the limb. The distance between the receiver crystal and the first and second transducers are represented by respective first and second chords of the cross-section of the limb and the predetermined distance between the first and second transducers is represented by a third chord of the limb cross section
Modeling of air flow through sinter mix bed
The present work relates the flow of air through a packed sinter mix bed to the pressure drop using the Ergun’s Equation. The velocity of air infiltration across the sinter mix charged into a pot was measured at different suction pressures. The parameters, void fraction and equivalent spherical diameter were calculated using the pressure drop and air velocity relationship. These have been interpreted in terms of the process variables vis-à -vis the mix permeability The validity of the Ergun’s equation was checked while comparing the observed pressure drop with the computed one obtained by fitting the above parameters in the equations
Effect of flux granulometry and other process variables on the sintering of iron ore at high basicity
Elimination of raw limestone from the blastfurnaee burden is known to bring a considerable saving in coke rate. In a country like India or elsewhere, the capacity of the sintering plants is limited it is imperative to produce super fluxed sinter and use it in the furnace. The basicity requirement coupled with the higher gangue input through coke and iron ore demands for a greater amount of flux in the mix. This situation is different from the frequentl y reported prac¬tice elsewhere in the world. So the flux size has crucial effect in the sintering. However this has not been reported adequately. In order to bridge the gap in the literature, sintering study was carried out using factorial design. Five factors were studied at two levels. Data generated through the experiments were analysed using the statis¬tical procedure and the regression equations were established for the following sintering indices in terms of significant factors and interactions. The flux granulometry has crucial role in the produc¬tion of sinter at basicity level of 3.25. The sintering indices are adversely affected when the sinter mix contains higher amount of ¬0.5 mm size fraction in it. The thermal and X-ray diffraction analy¬ses of the sinter and return fines sample reveal that the limestone is not properly calcined properly to be assimilated by hematite. A sav¬ing in the consumption of coke breeze upto 10% can be achieved through improvement in gasodvnamic in the sintering bed when -0.5 mm size fraction in limestone is restricted. Based on the above ob¬servation a modification in the existing crushing scheme of lime¬stone are proposed
Improvement in Quality Parameters of Super-Fluxed Sinter from Indian Iron Ores: NML’s Experience
The various studies at NML report that the quality parameters of sinter could be improved by modifying the physical characteristics of the sinter mix and improving the thermal efficiency.
The studies have shown that increasing the solid fuel consumption was not a viable solution to improve TI and RI simultaneously. The mineralogical and morphological compositions of sinter do affect its qualities : A higher amount of calcium ferrites improved the reduction-degradation index and reducibility of sinter. The reducibility was well correlated with the ratio of micro-pores to total pores in sinter. Grain size of the mix did affect the sintering speed and quality parameters. The studies also show that significant improvement in reduction properties could be achieved by narrowing down the flux size and that of coke as well as optimizing the process variables. The RDI also improved with the addition of polymer in the mix, however, sinter productivity decreased
Application of Statistical Analysis in Sintering and Blast Furnace Iron Making
Statistical techniques are used to represent a physical situation functionally and/or to confirm a hypothesis. Statistical techniques are of considerable help in analyzing the performance of a complex system, such as
a blast furnace , which is subjected to a large number
of inter-influencing variables
Coke Making from Coal: Scope for SSI
The technological developments have opened up new avenues for small scale industries (SSI). The SSI sector has proved its mettle even in the changed liber-alised economic environment of the nation. The SSI
sector is riddled with certain problems. It is therefore need of the hour to strengthen the SSI sector and enhance its competitiveness domestically and globally — for this the sector must be provided sustenance through suitable measures
Fundamentals of Iron Ore Sintering
The process of sinter making originated from a need to make use of fines generated in mines and in ore bene-fiCiation plants. With the development of sintering technology, a sintering plant has become a tremendous success for providing a phenomenal increase in prod-uctivity and saving in coke rate to the blast furnace.
The technology of sinter making has undergone radical changes both in operation and process throughout the world.
High competitiveness amongst the iron and steel industries has forced the operators to radically modify their operat-ion in several fronts including the raw material preparat-ion through sintering. In this regard It is essential to understand the sintering fundamentals
De-Watering of Iron Ore Fine Particles in Aqueous Medium
Solid - liquid separations form an integral part of many mineral processing and hydrometallurgical operations. During the wet processing of iron ores, a considerable amount of fine particles, known as slimes, are generated which need to be recovered effectively through solid -liquid separation. This assumes even more importance in case of iron ores in view of the large tonnage treated
in India or elsewhere in the world. Proper dewatering
is essential
Inter-influencing factors in affecting BF coke rate – statistical approach
A blast furnace (BF) is a multivariate system which is subjected to a large number of inter-influencing variables affecting its performance: productivity and coke rate. It is important to isolate the inter-influence before drawing any conclusions. It is essential to support the parameters’ effect (on the responses) through theoretical consideration. .
The explanatory variables affecting the coke rate have been statistically analysed in case of typical BF at Bhilai Steel Plant, SAIL and discussed in the present paper. The results (sixteen years’ monthly average data points) show that some variables are not orthogonal which have been explained in terms of (a) natural cause and effect relationship amongst the variables and (b) apparent inter-relationship amongst the explanatory variables and masking the effect. The inter-influences of the variables have been isolated and their effect on coke rate has been discussed which are substantiated by the theoretical consideration.
The study shows that the variable, burden rate was the most significant one followed by temperature of hot blast. A change in burden rate has been mainly reflected by a change in weight of raw limestone in the burden.. The adverse effect of the variables, ash content of coke was inter-influenced by the variable, limestone consumption. However, analysis shows the variable, ash content in coke affected the coke rate, though marginally when the inter-influence was isolated. The range studied against this variable during the period was quite high: 12 to 554 kg/ THM which indicates that lump ore constituted high proportion in the burden with nearly zero sinter consumption during some period. The empirical equation, established through the analysis of more recent data shows that an increase in ash content of coke (range 21.5- 26.6%) increased the carbon rate and the correlation coefficient was similar to those observed previously.
The study indicates that an equation developed need to be modified when the value of an independent variables deviates from the range of data considered in the analysis
- …