Magnesium oxide spray dryer

It is typical to install the spray-dryer before the plant fly-ash collector, so that the existing dust control equipment can be used to collect the used absorbent. Slaked lime [Ca(OH)2] is the most common absorbent, although sodium carbonate (Na2C03) is used in some plants. Spray-dryers have also been used with regener-able magnesium oxide absorbent. " ... 

An improved magnesium oxide (MgO) flue gas desulfurization process and its comparative economics are described. Innovations made include the use of a spray dryer, a cyclic hotwater reheater, and a coal-fired fluidized-bed reactor for regeneration of the MgO absorbent. Several technical concerns with the proposed design are addressed, including fly ash and chloride buildup. The economic evaluation shows the process to have a capital investment of about seven percent less than that of a conventional MgO scrubbing process and a 40 percent smaller annual revenue requirement. Finally, a sensitivity analysis is shown relating annual revenue requirements to the byproduct sulfuric acid price credit. 

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