Atmospheric Pollution Control in Coke Ovens

Production of iron through BF route is still a dominant route and coke is a major raw material and energy source for the blast furnaces. The process of coal carbonization in slot ovens in one of the major sources of atmospheric pollution in an Integrated Steel Plant. Coke making proc-ess involves coal preparation, carbonization and coke handling operations. To meet the demand of Blast Furnaces of SAIL plants, about 12 million tones of coal are carbon-ized every year in 26 operating coke oven batteries in the different plants. The coke making process is a well-documented source of pollution in terms of gaseous and particulate emissions. CPCB norms for emissions from the different sources of coke oven have been notified through gazette notificat-ions. However, it is very important that the methodology and frequency of measurement are to be standardized for all the coke oven plants in India. SAIL is well aware of the problems of pollution in coke oven batteries and a number of measures have been intro-duced to meet the challenges of emission control from coke ovens viz. smokeless charging, water-jet cleaning of doors, introduction of selective crushing/groupwise crus-hing of coals, new door design, water sealing of A.P. caps, introduction of tall ovens etc. The paper discusses some of these measures adopted in coke ovens for the control of pollution

Preliminary studies on the baking of chapatties

Assuming that the degree of baking is determined by percentage loss of moisture content, and that conduction of heat is the predominant factor in the baking of the 'Chapatties', an equation has been derived on the basis of a few simplifying assumptions, expressing the percentage moisture loss as a function of baking time and thickness of chapatties. The limitations of the equation have been discussed in the light of some preliminary observations taken under laboratory conditions, and the equation has been modified accordingly, in order to represent the experimental data with reasonable accurac

Exact transient analysis of a circulant queuing network

AbstractCirculant matrices possess unusual and interesting properties. These properties have been exploited to obtain the transient solution in closed form for a circulant queuing network that models a distributed query processing system. The sojourn time of a customer in the circulant queuing network is determined. A semi-Markov generalisation of this network is also studied

Synthesis of bulk, dense, nanocrystalline yttrium aluminum garnet from amorphous powders

Amorphous powders of Al2O3x2014;37.5 mol% Y2O3 (yttrium aluminum garnet (YAG)) were prepared by coprecipitation, decomposed at 800xB0;C, and hot-pressed uniaxally at low temperature (600xB0;C) and a moderate pressure (750 MPa). Optimum conditions yielded microstructures with only 2% porosity and partial crystallization of YAG. Further processing using high quasi-hydrostatic pressure (1 GPa) at 1000xB0;C enabled the production of fully crystallized YAG with gt;96% relative density and a nanocrystalline grain size of x223C;70 nm. 13

Transforming Urban Governance to Manage Uncertainty and Climate Change in Mumbai, India

Despite unprecedented wealth accumulation, coastal Mumbai suffers from a myriad of socioeconomic and ecological challenges as well as connected uncertainties. These include endemic flooding, shrinking of sensitive ecosystems, inequality, and marginalisation of natural resource-dependent communities, such as fishers. These are in addition to existing risks, including building collapse, fire hazards, infrastructure collapse, industrial accidents, and landslides. The spectre of climate change looms large and further complicates the situation. Urban governance mechanisms and strategies respond insufficiently to the growing threats the city faces. More needs to be done to manage and address these uncertainties through a strategic, adaptation-focused, and communicative urban governance framework that emphasises both reducing risk and strengthening social justice.Research Council of Norwa

The rapid evolution of the exciting star of the Stingray Nebula

SAO244567, the exciting star of the Stingray nebula, is rapidly evolving. Previous analyses suggested that it has heated up from an effective temperature of about 21kK in 1971 to over 50kK in the 1990s. Canonical post-asymptotic giant branch evolution suggests a relatively high mass while previous analyses indicate a low-mass star. Fitting line profiles from static and expanding non-LTE model atmospheres to the observed UV and optical spectra, taken during 1988-2013, allowed us to study the temporal change of effective temperature, surface gravity, mass-loss rate, and terminal wind velocity. In addition, we determined the chemical composition of the atmosphere. We find that the central star has steadily increased its effective temperature from 38kK in 1988 to a peak value of 60kK in 2002. During the same time, the star was contracting, as concluded from an increase in surface gravity from log g = 4.8 to 6.0 and a drop in luminosity. Simultaneously, the mass-loss rate declined from log (dM/dt/Msun/yr)=-9.0 to -11.6 and the terminal wind velocity increased from 1800km/s to 2800km/s. Since around 2002, the star stopped heating and has cooled down again to 55kK by 2006. It has a largely solar surface composition with the exception of slightly subsolar carbon, phosphorus, and sulfur. By comparison with stellar-evolution calculations, we confirm that SAO244567 must be a low-mass star (M < 0.55 Msun). However, the slow evolution of the respective stellar evolutionary models is in strong contrast to the observed fast evolution and the young planetary nebula with a kinematical age of only about 1000 years. We speculate that the star could be a late He-shell flash object. Alternatively, it could be the outcome of close-binary evolution. Then SAO244567 would be a low-mass (0.354 Msun) helium prewhite dwarf after the common-envelope phase, during which the planetary nebula was ejected.Comment: 16 pages, 13 figures, accepted for publication in A&

Acute Corrosive Injuries of the Stomach: A Single Unit Experience of Thirty Years

Introduction. The spectrum of gastric injury due to corrosives can vary. This paper presents a single center experience of over 30 years of corrosive gastric injuries of 39 patients with acute gastric injuries from 1977 till 2006. Patients and Methods. Two thirds of the patients in the acute injury group had a concomitant esophageal injury. The age of the patients ranged from 4 years to 65 years with a slight preponderance of males. (M : F ratio 22 : 17). Results. 36 out of 39 acute gastric injuries were due to ingestion of acids. Three patients had history of caustic soda ingestion. Oral hyperemia or ulcers of varying extent were seen in all patients. The stomach showed hyperemia in 10, extensive ulcers in 13, and mucosal necrosis in 10 patients. Fifteen patients (15/39, 38.5%) were managed conservatively. Twenty four patients (24/39, 61.5%) underwent laparotomy: one for frank peritonitis, 10 for gastric mucosal necrosis, and 13 others for extensive gastric ulcerations. Overall the mortality rate was 29.6 %. Conclusion. Although the mortality and morbidity of acute corrosive gastric injuries is high, the key to improve the survival is early identification of perforation, maintenance of nutrition and control of sepsis

The Future of Direct Reduction Processes

New production processes find application depending on the demands and opportunities afforded by changing times and conditions. This is also true of direct reduction proce-sses which, after a period of testing and development, are now receiving attention for wider industrial application because the need for it is beginning to be felt. A few direct reduction processes have already been commercially accepted