Development of a Dynamic Model and Control System for Load-Following Operation of Supercritical Pulverized Coal Power Plants

Thermal power plants that have been designed to operate at their rated capacity are being forced to cycle their load and operate under low-load condition to meet changing load demands due to the increased penetration of renewables into the electric grid. The rapid load-following operation is leading to challenging control problems. The goal of this research is to develop dynamic model and control system for efficient load-following operation. The focus of this work is on supercritical pulverized coal (SCPC) power plants. The steady-state model is developed using Aspen Plus and Aspen Custom Modeler and then converted to a pressure-driven Aspen Plus Dynamics model, where the regulatory control layer and coordinated control system (CCS) are developed for efficient servo control and disturbance rejection characteristics. A detailed three-region dynamic model of the feed water heater is also developed. The model can estimate the changing size of desuperheating, condensing and subcooling zones during load-following. As key components of CCS, control strategies for the coal flow, air flow, boiler feedwater flowrate and reheat steam temperature are developed. The control strategy for the main steam temperature control is developed with due consideration of the time delay of the SCPC syste

Sodium gluconate: An efficient organocatalyst for the synthesis of dihydropyrano[2,3-c] pyrazole derivatives

Sodium gluconate presented as a category of biomolecule found to be a proficient and recyclable organocatalyst for the synthesis of dihydropyrano[2,3-c]pyrazole derivatives via one-pot multicomponent reaction of aryl aldehyde, malononitrile, ethyl acetoacetate and hydrazine hydrate in water as a solvent. The catalyst is non-toxic in nature, commercially available, biodegradable and easily separated from the reaction mixture. Present protocol avoids the use of the heavy metal catalyst, harsh reaction condition and the reusability of catalyst, broad substrate scope, simple work-up procedure and excellent yield of products make this protocol greener.               KEY WORDS: Pyrano[2,3-c]pyrazole, Sodium gluconate, Multicomponent reaction (MCR), Knovenagel condensation, Bio-based organocatalyst Bull. Chem. Soc. Ethiop. 2019, 33(2), 331-340.DOI: https://dx.doi.org/10.4314/bcse.v33i2.1

The action of polar adsorbates on nylon 66

The present investigation deals with two broad aspects of fibre research both directed towards the elucidation of the role of the polar groups in polyamides and polypeptides. (1) The study of the Interaction of certain disaggregating polar reagents like lithium bromide, lithium perchlorate and magnesium perchlorate with nylon 66. (2) The study of changes in sorption of water, when polyamide (nylon 66) and polypeptide (silk) fibres are subjected to a tensile deformation. The effect of polar reagents on the dimensions and tensile characteristics suggests a possibility of interaction at the polar group. The changes in X-ray diffraction patterns revoal a significant decrease in the ? form, and an annealing effect. The interaction is confined to the polycrystalline regions, and the reagents do not produce setting of nylon. It is suggested that ? form appears towards the edges of the crystallites. The N.M.R. and the infrared study of N-ethyl acetamide (model compound) suggests a possibility of an interaction between polar reagent and the CONH groups. Nylon filme treated with polar reagents show a new absorption peak at 3390 cm-1. which changes on deuteration to 2518 cm-1. It has been shown that this is a new NH peak and that it may have slight parallel dichroism. An ion-dipole interaction mechanism has been suggested which favours the possibility of co-ordination of ions with the lone pair electron of the nitrogen atom. The change in regain of nylon with strain, at different humidities (13, 35, 52, 66 and 93% r.h.) have been measured. Regain increases with increased strain, but, except at 13% r.h., the changes have been found to be independent of humidity. It is interesting to note that the changes in regain are quite appreciable (about 1.0% moisture regain for 8% strain), and are in agreement with those calculated from stress relaxation of nylon at different humidities. The calculated changes in volume from the known value of poisson's ratio for nylon. agrees fairly well with the observed change in regain. The changes in regain of silk under strain vary with the changes in surrounding humidity. At 65% r.h. the changes are comparable to those for nylon 66. The results have been interpreted in terms of stress relaxation mechanism. The longitudinal swelling of nylon has been measured under a constant load of 2.4g/denier. On substituting suitable values from the above experiments in the thermodynamic equation a reasonable agreement between the calculated and the experimental values of the reversible modulus for nylon 66 has been found. It has been postulated that the interaction of water with nylon is confined to the rotational energy levels of the systems. This postulate has been extended to various observed phenomena as follows. (a) The change in ?'-loss modulus peak for nylon as a result of increase in temperature or humidity, involves two different molecular mechanisms. (b) The similarity between stress relaxation behaviour of different fibres in water has been attributed to a possibility of interaction of water with the rotational energy levels of various fibrous systems; regardless of the presence of specific interchain interactions in some hydrophilic fibres. (c) An alternative explanation for the sigmoid shape of the curves of rigidity modulus against humidity for nylon has been proposed: this is in conformity with the spectral evidence that there are no free NH groups in nylon 66. (d) A possible mechanism for setting of nylon 66 has been suggested, and it has been shown that the weakening of inter-chain interaction alone is not sufficient to impart desirable dimensional stability. A hypothetical system has been proposed which explains that the relative movemont of segments is not the sole contributor to stress relaxation, and that the main chains may play an important role

Assessment of cardiac complication in diabetic patient of rural India

Background: Diabetes mellitus (DM) is a common endocrine disorder affecting approximately 382 million people worldwide. Diabetes mellitus (DM) is group of metabolic disorder in which glucose is underutilized, thus producing hyperglycemia resulting from a defect in insulin secretion, action, or both. Cardiovascular disease is the most common cause of death and disability among people with diabetes. The cardiovascular disease that accompany diabetes include angina, myocardial infarction (heart attack), Stroke, peripheral artery disease and congestive heart failure. In people with diabetes, high blood pressure, high cholesterol, high blood glucose and other risk factors contribute to the increased risk of cardiovascular complications.Method:  This study was conducted to determine the cardiac complication in diabetic patient of rural India. It was Cross sectional retrospective study, done in between period of January 2018 to December 2019.Result: In the present study authors found that   47.7% patients have Coronary artery disease (CAD), Silent 21.6% have myocardial ischemia (SMI), 36% Diastolic dysfunction (DF), 28.8% have Systolic dysfunction (SDF).Conclusion: In this study authors found that wide spectrum of cardiac complications in diabetic patients ranging silent myocardial ischemia to heart failure. CAD was the most common complication including silent myocardial ischemia (SMI) which is the one of the major concern of rural diabetic population which need proper screening by exercise treadmill test

Role of acute viral hepatitis as a confounding factor in antituberculosis treatment induced hepatotoxicity

Background & Objective: Drug induced hepatotoxicity (DIH) is an important and commonly encountered adverse effect with antituberculosis (anti-TB) treatment. Acute viral hepatitis (AVH) is an important confounding reason which clinically, biochemically and histologically mimics DIH. Methods: The contributory role of acute viral hepatitis as a confounding factor in patients with normal baseline liver functions who developed acute hepatitis while receiving short-course anti-TB treatment was prospectively studied. The sera of all patients who developed acute hepatitis were analysed for markers for hepatitis A, B, C and E viruses. Results: Viral hepatitis was present in 15 of the 102 (14.7%) patients who developed acute hepatitis while receiving anti-TB treatment with hepatitis E virus being the most common cause Later onset of acute hepatitis [58 (5-133) vs. 26 (3-221) days; P=0.04], large elevations in aspartate aminotransferase (AST) [371 (30-2643) vs. 212 (63-1990 IU/l); P=0.03] and alanine aminotransferase (ALT) [388 (31-2997) vs. 225 (52- 1670 IU/l); P= 0.002] and a longer time for normalization of deranged liver functions [36.7 ± 13.3 vs. 24.5 ± 19.3 days; P=0.02] indicated acute viral hepatitis as the cause of liver function derangement. Interpretation & Conclusion: Our findings showed AVH in 14.7 per cent patients who developed hepatotoxicity while an anti-TB treatment. Therefore, in endemic areas, viral hepatitis should be sought after and excluded in all patients suspected to have DIH before attributing the hepatotoxic effect to the anti-TB drugs

The effect of tranexamic acid on artificial joint materials : a biomechanical study (the bioTRANX study)

Background Tranexamic acid (TXA) has been successfully used to reduce bleeding in joint replacement. Recently local TXA has been advocated to reduce blood loss in total knee or hip replacement; however, this raised concerns about potential adverse effects of TXA upon the artificial joint replacement. Materials and methods In this biomechanical study we compared the effects of TXA and saline upon the following biomechanical properties of artificial joint materials—(1) tensile properties (ultimate strength, stiffness and Young’s modulus), (2) the wear rate using a multi-directional pin-on-plate machine, and (3) the surface topography of pins and plates before and after wear rate testing. Results There were no significant differences in tensile strength, wear rates or surface topography of either ultra-high-molecular-weight polyethylene pins or cobalt chromium molybdenum metal plates between specimens soaked in TXA and specimens soaked in saline. Conclusion Biomechanical testing shows that there are no biomechanical adverse affects on the properties of common artificial joint materials from using topical TXA. Level of evidence