Next-generation, affordable SO2 abatement for coal-fired power generation - A comparison of limestone-based wet flue gas desulphurization and Sulfacid® technologies for Medupi power station

Abstract

SYNOPSIS Coal is used to generate more than three-quarters of South Africa's electricity, while numerous coal-fired boilers are employed for steam generation in industrial processes. However, coal-fired power generation is responsible for the release of the largest quantities of SO2 emissions to the atmosphere and leads to detrimental health and welfare effects in communities in the proximity of coal-fired plants. The classical industrial SO2 abatement solution for the coal-fired power generation industry is wet flue gas desulphurization, which uses a limestone adsorbent and produces a gypsum by-product (WFGD L/G). In South Africa, due to the poor quality of the limestone the gypsum product is unsaleable and is co-disposed with coal ash. In comparison, the Sulfacid® process technology converts SO2 contained in industrial flue gas into saleable sulphuric acid using a catalytic process requiring only water and air. This process does not require limestone. The scale of the latest commercial applications of the Sulfacid® SO2 abatement technology in the chemical, fertilizer, and copper mining industries demonstrates the potential and readiness of this technology to be employed in the coal-fired electricity and steam production sectors. This paper provides a first-order direct comparison between the techno-economic aspects of the WFGD (L/G) and Sulfacid® technologies using the requirements specified for the 6 x 800 MWe Eskom coal-fired Medupi power station. The results indicate that affordable flue gas desulphurization technology exists that could be adopted by the South African industry to reduce SO2 emissions to legislative limits and beyond. Keywords: SO2 abatement, coal-fired power, and heat generation, sulphuric acid, wet fluidized gas desulphurization, Sulfacid®, waste-to-chemicals.

Treatment of Flue Gas Desulphurisation Effluent with Freeze Crystallization

“…A wet limestone FGD system typically includes the following unit operations: limestone preparation, storage and handling system, FGD spray tower absorber, dewatering system of the resulting by-product and wastewater treatment system [4,5,6,7].…”