23 European Symposium on Computer Aided Process Engineering
23 European Symposium on Computer Aided Process Engineering

Author: Claudio Carletti

Publisher: Elsevier Inc. Chapters

Published: 2013-06-10

Total Pages: 16

ISBN-13: 0128085495

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Anthropogenic sulfur dioxide (SO2) is principally the product of energy conversion through combustion of fossil fuel sources. This pollutant causes acidic rain and can also be harmful for human health. Many means for controlling sulfur dioxide emission are available in the market and have been extensively applied. Among these techniques, wet flue gas desulfurization is one of the most widely used methods because of its reliability and high efficiency. Nonetheless, high energy and water consumption are among its principal drawbacks. Limestone dissolution has been accounted as one of the main controlling steps of the process (). Even though limestone is dissolved in acidic media in many industrial processes worldwide, no commonly accepted mathematical models exist for the dissolution kinetics at the moment. The reasons for the contradictory results in literature dwell, at least to considerable extent, from the varying influence of mass transfer limitations and the influence of CO2 on the pH. Experimental equipment and a methodology for evaluating the kinetic regime of a high grade limestone commercially used for desulfurization was developed in the current study. The results show that the kinetic regime, necessary to properly characterize the dissolution rate, can be reached even with small particle size and high temperatures with the help of severe agitation to overcome solid-liquid mass transfer and powerful purging to minimize the influence of carbonic acid on the pH. The method can be directly applied for investigating and comparing the reactivities of various limestone samples for industrial purposes.

Recovery and Recycling of Limestone in LEC Flue Gas Desulfurization. Final Report, Third Year
Recovery and Recycling of Limestone in LEC Flue Gas Desulfurization. Final Report, Third Year

Author:

Publisher:

Published: 1993

Total Pages: 31

ISBN-13:

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A potentially attractive flue gas desulfurization method called Limestone Emission Control (LEC) is currently being investigated by Prudich at Ohio University. In this process, beds of 1/8 inch limestone gravel particles absorb sulfur dioxide from flue gas. This forms sulfite and sulfate salts which coat limestone, blinding the surface and limiting utilization to 20%. Favorable economics can be generating when the unreacted portion of the limestone is recovered by mechanical grinding. This project is a wet method for grinding and recovering the spent limestone from the LEC process, utilizing an impeller fluidizer, a new type of slurry processor. It consists of a cylindrical vessel with an impeller at one end. The impeller generates sufficient pressure head to serve as a slurry pump. It combines the operation of wet grinding, washing, and transporting the spent and recovered limestone as an aqueous slurry. The objectives of the first two years were to operate fluidizer in a batch mode to carry grinding experiments, and to determine the removal of the sulfur coatings from the limestone when operating the fluidizer in a continuous mode. The main thrusts of the third year were to complete the grinding data and coordinate the data with reactivity determinations of the recovered limestone. Direct measurement of power requirements, operation of single impeller fluidizer, grinding of surface deposits and other methods of removing surface deposits have also been investigated along with sorption characteristics of recovered limestone, microscopic examination of the limestone surface, and limestone attrition.