FGD By-products Research Articles

Oxidation, reemission and mass distribution of mercury in bituminous coal-fired power plants with SCR, CS-ESP and wet FGD

Mercury (Hg) speciation variations in flue gas at the inlet and outlet of various air pollution control devices (APCDs) were studied, including a selective catalytic reactor (SCR), a cold side-electrostatic precipitator (CS-ESP), a wet flue gas desulfurization system (wet FGD) and the stack of bituminous coal-fired power plants. Effects of flue gas temperature, flow rate and selected flue gas components on Hg oxidation were also studied. The association of selected parameters on Hg0 oxidation and removal by the APCDs and the mass distribution of Hg within the system were estimated. Sampling and analysis were carried out using the Ontario Hydro Method. Solid and liquid samples were analyzed according to US EPA methods 7470A and 7471A, respectively. Hg concentration in the flue gas at the outlet boiler and stack ranged from 4.70 to 27.3μg/Sm3 and 3.1 to 0.48μg/Sm3, respectively. The overall Hg removal efficiency in the APCDs ranged from 43.8% to 94.9%, and oxidized Hg in flue gas decreased with increasing temperature. With an increase in HCl concentration, a decrease in flue gas flow rate and decreasing temperature, oxidation of elemental Hg in combustion flue gas increased. The effects of SOx and NOx concentrations on elemental Hg oxidation in flue gas were rather complex. Among the parameters studied, the most significant parameters affecting overall Hg removal in the APCDs, in order, were removal in the ESP, oxidation in the SCR system and removal in the wet FGD. Experimental data and statistical analysis confirmed the promotion of a co-beneficial control of Hg in the SCR, CS-ESP and wet FGD configurations. The mass distribution showed that 43.0% of Hg was collected in ESP fly ash, 49.4% in wet FGD by-products and effluents, 3.9% of Hg was removed in boiler bottom ash and 3.7% was released into the atmosphere. In the SCR+CS-ESP+wet FGD configuration, a major portion of Hg was distributed into the by-products and removed by the APCDs compared to the lower removal levels seen in the CS-ESP+wet FGD configuration.

Experimental Study on Utilization FGD Byproducts in Building Bricks

This paper discussed the feasibility of unburned and non-autoclaved, steam cured bricks prepared by FGD byproducts from coal-fired power plants. The results show that FGD byproduct, aggregates, cementious materials and water could be used to prepare bricks during the process of stir and compaction under natural cure and steam cured condition. S4 and Z2 are the optimum design mixture composition. The maximum compressive strength and saturation coefficient are 28.7 MPa and 96.7%. FGD byproducts do no harm to environment and a pilot-scale experiment demonstrates that bricks made with FGDA can meet the MU10 level bricks technical requirement.

97/03785 FGD by-product production at Petersburg Station

97/03785 FGD by-product production at Petersburg Station

THE DEVELOPMENT OF A KNOWLEDGE-BASED EXPERT SYSTEM FOR UTILIZATION OF COAL COMBUSTION BY-PRODUCT IN HIGHWAY EMBANKMENT

Abstract The study in this paper introduces the development of a knowledge-based expert system that helps to determine the suitability of FGD by-product in embankment construction. The expert system shell Personal Consultant Plus was used for this purpose. The knowledge base in the Embankment Construction Expert System (ECES) consists of a root frame and four subframes, and accommodates the production rules obtained from laboratory tests as well as an extensive literature review. An external program to calculate the embankment settlement was integrated into the system. A case study is presented to demonstrate the use of ECES. This study provides the embankment designer with a useful tool for making decisions on FGD by-product application as an embankment material.