Management of Spent Organic Ion-Exchange Resins by Photochemical Oxidation

Management of spent ion-exchange resin waste arising from nuclear reactor operations by traditional practice of encapsulation in cement is associated with problems such as swelling and disintegration. Complete oxidation (mineralization) is an attractive alternative option. This paper reports the development of photochemical mineralization process for organic ion-exchange resins of poly (styrene-divinyl benzene) type with sulfonic acid and quaternary ammonium functional groups. It is a two-step process consisting of dissolution (conversion of solid resin into water-soluble reaction products) and photo-Fenton mineralization of the dissolved resin. Cation and anion resin dissolution was effected by reaction of the resin with H2O2 at 50-60 C in the presence of ferrous/copper sulphate catalyst. Direct dissolution of mixed resin was not efficient. However, the cation resin portion in the mixed resin could be selectively dissolved without affecting the anion portion. The solid anion resin after separation from the cation resin solution could be dissolved. About 0.5 liters of 50% H2O2 was required for dissolution of one kg of wet resin. The reaction time was 4-5 hours. Dissolution experiments were conducted on up to 8 liters of wet resin. The second step, viz., photo-Fenton mineralization of the dissolved resin was effected at ambient temperature(25-35 C). Kinetic results of laboratory scale experiments in immersion type photo-reactor and pilot scale experiments in tubular flow photo-reactor were presented. These results clearly demonstrated the photo-Fenton mineralization of dissolved resin at ambient temperature with stoichiometric quantity of H2O2 as against 70-200% excess H2O2 requirement in chemical mineralization experiments under Fenton oxidation conditions at 90-95 C. Based on these studies, a treatment scheme was developed and presented in this paper

Impact of inclination on single phase heat transfer in a partially filled rotating pipe

Heat transfer in a partially-filled, rotating inclined pipe with water flowing through it is experimentally investigated. The test section is a 1000 mm long stainless steel pipe with 32.8 mm inner diameter and 1.1 mm wall thickness. The outer wall is painted black to improve its emissivity. The outer wall temperature distribution is captured using a thermal camera. Uniform wall heat flux (1405-10784 W/m(2)), water volumetric flow rate (100-830 ml/min), rotation rate (10-300 RPM) and pipe inclination angle (3 degrees and 6 degrees) are varied to study their influence on the heat transfer coefficient. Local heat transfer coefficient along the length of the partially filled rotating test section is reported. While heat transfer coefficient increases with the increase in wall heat flux, liquid volume flow rate and rotation rate, it decreases with increase in inclination angle. A generalised correlation to predict the average Nusselt number is developed in terms of four dimensionless numbers, viz., the flow Reynolds number to capture the effect of the axial fluid flow, rotation Reynolds number to account for the effect of pipe rotation, flow Froude number to take care of the effect of pipe inclination and dimensionless heat flux to incorporate the effect of wall heat flux on the heat transfer coefficient. (C)2018 Elsevier Ltd. All rights reserved

Heat transfer in a partially filled rotating pipe with single phase flow

Single phase heat transfer in a partially-filled, rotating horizontal pipe with axial liquid (water) flow is studied in this work. Thermal imaging is used to capture outer wall temperature of the partially filled rotating heated pipe. Local heat transfer coefficient along the length of the rotating pipe is calculated. Various parameters influencing the heat transfer coefficient i.e. heat flux (779-12522 W/m(2)), flow rate (6-80 LPH) and rotation rate (5-300 RPM) are identified and reported. It is observed that heat transfer is positively influenced by heat flux, flow rate and rotation rate. A generalised correlation is developed based on dimensionless heat flux, flow and rotation Reynolds number to predict the average Nusselt numbers. This study is expected to provide insight into single phase heat transfer characteristics of a partially filled rotating heated pipe