To comply with impending regulations on Hg emissions, coal-burning utilities need to evaluate the performance of various Hg control technologies, particularly SCR/ESP/FGD combinations and activated carbon injection (ACI). Unfortunately, the performance in field testing varies significantly with coal quality, and with the configuration and operation of units in the gas cleaning system. Since 1998, NEA has been developing and validating reaction mechanisms to describe Hg transformations throughout coal-fired gas cleaning systems. Unlike simple engineering regression models which account only for statistical correlations of plant data, NEA’s reaction mechanisms use the distinctive fuel properties and operating conditions at each particular gas cleaning system within a company’s fleet of power stations. NEA’s reaction mechanisms have been consolidated into a user-friendly computer package called MercuRator™ . About a dozen utility companies and utility OEMs in the U. S. and Japan are either using the package in-house or using its capabilities on a consulting basis. Learn More.

A major American utility R&D sponsor hired NEA to quantitatively interpret the entire backlog of mercury field tests sponsored by NETL of the U. S. DoE. The database represents about 200 distinct gas cleaning configurations at tens of power stations. This project was the final stage of validation for NEA’s MercuRator™ software package, which predicts the Hg emissions rate for any gas cleaning configuration with any coal or coal blend as accurately as they can be measured. About a dozen utility companies and utility OEMs in the U. S. and Japan are either using the package in-house or using its capabilities on a consulting basis. Learn More.

The United Nations Environment Programme wanted a fast way to estimate Hg emissions from power plants around the world that did not require technical sophistication or detailed engineering specifications. NEA responded with iPOG™, a user-friendly package that has already enabled hundreds of analysts to quickly identify their best Hg control options. Learn More.

A major American utility company sponsored NEA’s development of the SCR Catalyst Model, which predicts the performance of full-scale selective catalytic reduction units (SCRs) for simultaneous NO reduction, Hg⁰ oxidation, and SO₂ oxidation (Learn More) and, for the first time, accurately accounts for the impact of catalyst deactivation on Hg oxidation (Learn More).

NEA published the first computational analysis to identify the factors associated with the re-emission of elemental mercury from wet FGD scrubbers. The analysis first rectified assumptions in the conventional FGD simulation strategy that obscured trace metal transformations, then introduced distinctive expressions for sulfite oxidation and Hg(II) reduction in scrubber solutions. It is now being validated with several datasets from full-scale wet FGDs. Learn More.

NEA’s new Se mechanism describes Se transformations from the furnace through an ESP outlet, based on scavenging by iron aluminosilicates at furnace temperatures, and by lime in competition with SO₂ along gas cleaning systems.  The analysis has accurately described Se partitioning into particulate and vapor species at lab- and pilot-scale, and for a diverse assortment of fuels in about a dozen full-scale field tests. Learn More.

NEA developed the chemical conversion components for EPRI’s Waterwall Wastage program, which estimates the likelihood of steam tube corrosion near burners in full-scale furnaces by estimating the sulfide and chloride levels in slags for whole coals and blends.

A boiler manufacturer in Japan was concerned about excessive corrosion in its full-scale PFBC. They hired NEA to develop a computer simulator to identify which coals are likely to have excessive alkali vapor emissions. After the predictions satisfied evaluations against lab-scale test data, NEA delivered a software package that accurately predicted the alkali emissions from the pilot-scale PFBC, and was used to screen coals for the 230 MW Karita PFBC.

The main goal for NEA’s SCR poisons predictor is to accurately identify which poisons, in any, will be troublesome for specified fuel properties, furnace firing configuration, and gas cleaning conditions. The analysis accounts for incomplete vaporization within furnace flame zones; scavenging by molten aluminosilicates along upper furnace elevations; capture by ‘free’ CaO and sulfation through the back-end heat exchangers; and aerosol condensation into or within the SCR. Vaporization and aluminosilicate scavenging are described with thermochemical equilibrium calculations, while transport phenomena and chemical kinetics come into play in capture by CaO and sulfation at more moderate temperatures. Simulations have predicted the poison precursor concentrations at SCR inlets for a suite of ten different coal samples and a bituminous/wood blend.

A major American utility company sponsored NEA’s development of the SCR Catalyst Model, which predicts the performance of full-scale selective catalytic reduction units (SCRs) for simultaneous NO reduction, Hg⁰ oxidation, and SO₂ oxidation (Learn More) and, for the first time, accurately accounts for the impact of catalyst deactivation. Learn More.

NEA developed a combined homogeneous and heterogeneous SO₃ production mechanism to quantify the interference of SO₃ on the capture of Hg by unburned carbon (UBC) and activated carbon sorbents in flue gas. This mechanism was validated against measurements at different locations along the gas cleaning systems at fourteen power plants representing the entire range of coal–S, furnace stoichiometry, and gas cleaning conditions found in commercial applications. Learn More.

NEA’s SO₃ production mechanism has been integrated into MercuRator™ to account for inhibition of Hg oxidation and removal due to SO₃ condensation on fly ash, UBC and activated carbon. This analysis accurately interpreted Hg removals for numerous datasets that covered different coal blends, ACI concentrations, conventional and brominated activated carbons, and SO₃ concentrations. The simulations clearly identified the tests affected by SO₃ interference and predicted the Hg removal by ACI to within 15 % of the test measurements for 22 of the 27 tests. Learn More.