پياده سازي روشي جديد مبتني بر هدايت الكترونيكي براي كنترل عملكرد حوضچه آهك زني پالايشگاه اصفهان

چكيده انگليسي :

۸۷Utilizing a New Method based on Electrical Conductivity for the Control of Lime Clarifier Performance at Esfahan Refinery Parham Jafari p jafari@ce iut ac ir Date of submission September 16 2013 Department of Chemical Engineering Isfahan University of Technology Isfahan 84156 83111 IranDegree M Sc Language PersianSupervisor Mohamad Amiri amir33@cc iut ac irAbstractOne of the most important problems of industrial water is hardness Hard scaling decreasing in heat transferrate increasing energy consumption and need to chemical cleaning are factors that increasing the operatingcosts and environmental pollution Water hardness refers to the presence of dissolved divalent ions in water mainly of calcium Ca2 and magnesium Mg2 In addition to heat loss in heat exchangers hardness can causeproblems in process waters due to scaling of boilers agitated tanks pumps pipelines and other processequipment Water softening is a key process for separation of hardness ions in many industries to make thewater suitable for use in cooling towers or to prepare it for additional purification Failure to deal with thewater hardness can increase costs significantly because of reduced volumetric capacity reduced metallurgicalperformance increased downtime for mechanical de scaling or corrosion and premature equipment failure Lime Softening Process LSP is a voluminous process in the water utilities that consumes a considerableamount of chemicals mostly lime and produces a large volume of sludge Its performance can affect ondownstream purification processes such as sludge handling and demineralization units Upsets in LSP canoccur frequently and quickly and it may take days to render it fixed Two major components of operatingcosts of a softening process are lime consumption and sludge disposal both of them depend on performancemonitoring In this these investigation has been done on the lime processes for softening In this process lime is used for hardness reduction Performance control of this process is highly important for regulatinglime dosage and optimum hardness of treated water which are directly affected on desirability of the process Therefore conventional method for control of lime softening based on alkalinity has been investigated inaddition to checking modern method based on electrical conductivity The current method for performancecontrol of lime clarifier is based on measuring simple alkalinity P and total alkalinity M so that theamount of 2P M changes from 5 to 15 ppm as CaCO3 Pilot and full scale experimental results showed thatperformance control based on alkalinity is not always correct and reliable and it does not result in minimumhardness in treated water in addition to it consists of lengthy tests and using of expensive chemicals such asindicators and generation of chemical waste Our tests showed that with lime addition to water both totalhardness and also Electrical Conductivity of softened water decrease to a minimum value due to precipitationof insoluble products but then increase gradually as a result of excess lime In addition the bench scale testsdemonstrated clearly that minimum hardness in the LSP concurrent with minimum Electrical ConductivityExperimental results also show that measuring of electrical conductivity can be used as a simple nonexpensive and less sludge method for achieving minimum hardness in treated water without any chemicalwaste Pilot and full scale experimental results revealed that the performance control based on electricalconductivity is highly accurate in detecting the optimum operating conditions in addition to simplicity andeasy control without any chemical waste Keywords lime softening process electrical conductivity chemical method alkalinity

جعفري، پرهام

پياده سازي روشي جديد مبتني بر هدايت الكترونيكي براي كنترل عملكرد حوضچه آهك زني پالايشگاه اصفهان

نرم سازي , روش شيميايي , قلياييت