Preparation and Stabilization of high ash Indian coal samples using selective additives

Abstract

newlineEnergy is essential part of human civilization. At present the main source of newlineenergy comes from coal. Day by day the cost of energy generation increases resulting newlineavailability of energy becomes costly. With a view to reduce the cost of energy newlineproduction thereby reducing cost and increasing availability the present study has been newlinetaken up. Transportation of solid coal from mines to power plant has more scope for loss newlinein transit, environmental pollution due to pulverization at the plant site, cost for newlinewarehouse or storage and possibility of loss in fire. All these aspects are taken care of in newlinethe coal water slurry transportation project through pipeline. newlineHighly concentrated slurry with good stability and minimum viscosity has been newlineexamined by many investigators. A brief account of such endeavours has been hinted in newlinechapter 2 which reveals mostly flow behaviour of low ash coal water slurry. Availability newlineof coal in India specifically in Odisha is in nature of high ash coal. Present topic is an newlineattempt to examine the flow behaviour of high ash coal. newlineFlow behaviour of slurry implies the stipulation like high concentration, newlineminimum viscosity and optimum stability. High concentration ensures transportation of newlinemore solid coal. Reduced viscosity and stability help the slurry to flow smoothly through newlinepipeline. Transportation of solid particles in a fluid medium (water) requires thorough newlineinvestigation on particle size distribution of solid samples. Slurry containing range of newlinesingle sized particles result a concentration of 60% by weight but it exhibited a high newlineviscosity which deters flow. Reduction of viscosity called for introduction of additives in newlinethe slurry. In the present study, high ash and medium ash coal samples were used and newlinebased on the particle size different monomodal, bimodal and multimodal samples were newlineprepared. Rheological behaviour of monomodal slurry of high and medium ash coal was newlinestudied in the presence of bio additive, saponin extracted from Sapindous Mukorossi and newlineShikakai and three chemical additives (Glycerol, Glycol and Ethanol) of alcohol groups newlineseparately. The high ash coal samples could able to achieve a maximum coal newlineconcentration of 65% and 65.4% by weight using two selective bio additives such as newlineSapindous Mukorossi and Shikakai respectively. Similarly the use of Glycerol, Glycol newlineand Ethanol as a chemical additives could able to achieve a coal concentration of 64% by newlineweight. The comparative evaluation of all these selective additives (chemical and bio) newlinevi newlineindicated that Shikakai exhibited better coal loading for CWS preparation. Comparing newlinethe stability of the slurry, chemical additive proved better than other additives. Therefore newlinean attempt has been made to prepare a mixture additive of bio and chemical in bimodal newlinehigh and medium ash coal to achieve higher concentration and good stability. Two newlinemixture additives Saponin with SDBS (Sodium Dodecyl Benzene Sulphonate) and newlineSaponin with DDAB (Di Dodecyl Ammonium Bromide) have been tested in the medium newlineash and high ash bimodal sample. The study indicated that the mixture additive (saponin newlineand DDAB) with bimodal distribution for high ash coal resulted maximum coal newlineconcentration of 70% by weight with a stability period of 29 days. But for further newlineincrease in coal concentration an attempt has been taken in multimodal sample by newlinevarying the particle size fraction ratio i.e. coarse to fine coal samples of high ash coal. A newlinecoal concentration of 67.8% by weight has been achieved from the multimodal sample. newlineThus it is found that bimodal slurry in presence of saponin and DDAB has better newlinepotentiality for preparation of stabilized CWS which can be used for energy generation. newlinevii newlineCONTENTS newlineCertificate i newlineApproval Sheet ii newlineDeclaration iii