The new monitoring requirements being imposed on Medium Combustion Plants (MCPs) and Large Combustion Plants (LCPs) in Europe is symptomatic of environmental initiatives affecting a wide variety of industries. In the following article, Dr Andrew Dixon from Gasmet Technologies UK (formerly Quantitech) explains how instrumentation manufacturers are responding to these new challenges.
Gasmet - Continuous Mercury Monitor
The combustion of fuel and waste produces a wide variety of pollutants and greenhouse gases, so regulators around the world are increasingly imposing stricter emissions limits and monitoring requirements as part of initiatives to improve air quality and fight climate change. Generally, emission limit values are being lowered, the number of parameters being monitored is increasing, and the requirement for continuous monitoring is growing.
The growing number of parameters that have to be monitored means that operators have to employ multiparameter technologies such as FTIR, or purchase a number of analysers to meet the requirements. For this reason, Gasmet UK has developed an integrated systems capability, so that it is now able to design and build complete MCERTS approved monitoring systems, designed to meet plants’ individual requirements. However, one of the pollutants of major concern, mercury, necessitates a specific monitoring technology, and since the emissions limits are so low, it is necessary for this technology to have performance certification at these levels.
In Europe, member states have the opportunity to set specific limits and monitoring requirements that fit within the framework established by the Industrial Emissions Directive (IED). So, individual states may set stricter limits, or individual plants may implement more rigorous monitoring and abatement technology in order to demonstrate good environmental performance. In most cases, this is undertaken: as part of a corporate responsibility strategy; in response to demands from stakeholders, or in anticipation of tighter future regulatory requirements.
Mercury is considered by the World Health Organisation to be one of the top ten chemicals of major public health concern, so there are global initiatives to lower the emissions of this toxic element in its various compounds – particularly from power plants, waste combustion and cement plants.
In November 2015 the European Parliament signed a new directive that imposes emission limits on MCPs. Under the directive, an MCP is any equipment that burns fuel, with very few exceptions, and where the rated thermal input is between 1 and 50MW. Diesel or gas engine generators rated above 400kVA are also applicable, in addition to any appliance that uses fuel to generate heat or electricity. Boilers, generators and other mobile plants rated above 1MW thermal input are also included.
By regulating emissions to air of SO2, NOx and dust, the MCP directive aims to reduce air pollution and lower risks to human health and the environment. It has been estimated that the MCP directive will apply to over 30,000 plants in England and Wales. The controls will apply to new plants from December 2018, and to existing plants from 2024 or 2029.
New environmental standards for LCPs strengthen the requirements of the IED for both reduction and monitoring requirements. The new specifications stem from a review of the Best Available Techniques (BAT) Reference Document for LCPs, the so-called LCP BREF. This includes new BAT-associated emission levels (BAT-AELs) and sets new monitoring requirements for sulphur dioxide, nitrogen oxides, mercury, and particulate matter. The BAT conclusion was published in August 2017, and will come into effect with a four year transition period.
The LCP BREF applies to combustion plants with a total rated thermal input exceeding 50 MW. However, it also applies to smaller units where they are directly related to a combustion plant. This includes the gasification of coal and other fuels, and the waste co-incineration plants for non-hazardous waste (>3 tonnes/hour) or for hazardous waste (10 tonnes/day).
Continuous monitoring is required: for ammonia where NOx reduction by ammonia is employed; for mercury on plants ≥ 300 MWth, when coal and/or lignite is used, including waste co-incineration; and for hydrogen chloride when solid biomass and/or peat is used in LCPs or waste co-incineration plants.
The BAT-AELs for mercury emissions to air from coal and lignite burning power plants are extremely low. For example, a new coal-fired power plant with ≥ 300 MWth has a BAT-AEL of <1-2 μg/Nm
3 mercury (yearly average), and an existing lignite-fired power station with a thermal input under 300MW has a BAT-AEL of <1-10 μg/Nm 3 mercury.
It is interesting to note that the draft waste incineration BREF (WI BREF) also requires continuous mercury monitoring and currently stipulates a daily average of 5-20 μg/Nm
3 mercury emissions to air for new plants and 5-25 μg/Nm 3 for existing plants. In the BREF guidance for cement kilns (CLM BREF), mercury has a BAT-associated emission level of 50 µg/ Nm 3 for the half-hour average. However, in countries such as Germany, stricter emission limits have been adopted.
In some circumstances continuous mercury monitoring will be specified in the regulations, but in others, non-continuous methods may be allowed. This latter option may have a lower purchase cost, but it merely provides an average of a plant’s emissions over a certain time and therefore may not be considered the most effective way to protect the environment, because continuous monitoring provides a complete picture of a plant’s emissions. This helps to identify the source of pollution peaks, and to inform mitigation and abatement strategy. In addition, as emissions monitoring and control regulations become more stringent, continuous monitoring may become obligatory at a later date, for some types of plant.
Monitoring equipment must be MCERTS certified to perform within the requirements of a permit, which is why the possibility of continuous monitoring should be considered, and both current and future requirements for certified monitoring ranges and levels of uncertainty should be addressed. For these reasons, the recent certification of Gasmet’s Continuous Mercury Monitor (CMM) is of particular significance. The Gasmet CMM has successfully completed EN15267-3 testing using CVAF (Cold Vapor Atomic Fluorescence). Importantly, this instrument now provides the world’s lowest EN15267 certified range for measurements of Mercury. The CMM is certified for operation across a number of different ranges up to 1000 µg/m
3, but considering the latest regulatory requirements, the CMM’s certified range of 0 to 5 µg/m 3 will be of particular relevance to the operators of combustion processes.
In summary, when defining a monitoring strategy it is vitally important to take future requirements into account (from both regulators and stakeholders) when choosing appropriately certified technology. In addition, for new plants, monitoring requirements should be assimilated into the plant design at an early stage. Expert advice should be sought to ensure that the right equipment is specified in order to optimise the installation, ensure compliance and future-proof monitoring activities.