Implementation of mercury emission reduction in Project 200+
The requirements regarding the reduction of emission of pollutants into the atmosphere have evolved over the past few decades. At present, the BAT Conclusions published in the Official Journal of the European Union on 17 August 2017 are the basis for issuing integrated licences. As intended, the installation should be adapted to the requirements set out in the BAT Conclusions within a maximum of four years from the date of their publication in the Official Journal of the EU, i.e. by 17 August 2021. For many plants, heating plants, combined heat and power plants and utilities, this involves making difficult modernization and investment decisions in order to adapt the operating parameters of the plant to the new environmental requirements by 2021.
The conclusions adopted amend the existing Industrial Emissions Directive (IED Directive). The amendments concern the following aspects:
- More stringent requirements for such pollutants as: SO2 (sulphur dioxide), NOx (nitrogen oxides), dust and wastewater from flue gas desulphurisation plants.
- Introduction of new emission requirements for previously unregulated substances such as Hg (mercury), HCl (hydrogen chloride), HF (hydrogen fluoride) and NH3 (ammonia).
- Introduction of new monitoring requirements; annual and average daily values will apply, replacing the currently applicable monthly average values. Introduction of continuous monitoring for ammonia and mercury for large facilities.
Within a framework of implementation of units 200+ program, RAFAKO will, among other things, carry out an environmental task for reducing mercury emissions from flue gases. Mercury is one of the newly introduced components whose emissions will be supervised in accordance with emission standards resulting from the executive decision of the EU Commission. The mercury emission reduction method proposed in the project will allow the achievement of compliance of mercury emissions to the air, originating from combustion of hard coal, at the level covering the entire range required for 200MW class power-generating units.
The principle of application of a comprehensive Hg emission reduction technology.
The proposed method of reducing mercury emissions consists in the use of appropriately composed doses of additives in liquid and solid form, administered at several stages of both the coal combustion process and the individual flue gas cleaning processes.
The purpose is to develop a comprehensive deep mercury reduction method dedicated to a specific facility depending on the fuel combusted, flue gas characteristics and the expectations of the user of power-generating facility. The proposed solution shall enable a controlled reduction of mercury emissions at the selected stage of the flue gas cleaning process. The selection of appropriate doses of additives administered at appropriate locations of the flue gas line, depending on the specificity of the facility, will allow the control of the mercury reduction process by a combination of several of the following processes: increasing the share of oxidised mercury in the combustion process, increasing the adsorption of oxidised mercury on the particles of fly ash removed in dust removal systems, increasing the reduction of mercury emission in flue gas dust removal systems through the introduction of dust additive in impregnated or non- impregnated form, increasing the amount of mercury captured in the flue gas desulphurisation process.