European refiners to face environmental challenge

March 18, 2002
The European Commission has recently revised its Directive 88/609/EEC regarding the release of pollutants from large combustion plants.

The European Commission has recently revised its Directive 88/609/EEC regarding the release of pollutants from large combustion plants. According to a report from Concawe, the revision "includes an important and fundamental change, in that it prescribes the upgrading of existing plants to meet the same requirements as new plants."1

Concawe (Conservation of Clean Air & Water, Europe), Brussels, is a European organization representing oil companies' interests in environmental and health protection.

The revision will limit the amount of sulfur in the fuels that European Union (EU) refiners use in their furnaces and other fired heaters. It will be especially difficult on refiners that use heavy residues from the refining process for which there are no alternative disposal routes.

According to the report, it will be especially difficult on southern Europe refiners that process higher sulfur crudes. The revision breaks down thermal plants into three categories:

  • "Old" plants that started up before Jan. 7, 1987.
  • "New" plants that started up between Jan. 7, 1987, and Jan. 1, 2002.
  • "New new" plants that started up after Jan. 1, 2002.

SOx emissions

According to Concawe, refiners can comply with SOx emission limits through two alternatives: emission limit values (ELV) for individual combustion plants or an overall average "refinery bubble concentration."

The SOx emission requirements for new new plants are much tougher than for other plants, reported Concawe. Fig. 1 shows the sulfur in fuel oil that can be used to comply with SOx requirements for the different types of plants and different reporting methods. An equivalent thermal MW rating (MWth) determines plant size.

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The "jump" at 50% in Fig. 1 is due to the "majority fuel" concept. According to Concawe, the emission limit for mixed oil and gas firing is equivalent to the oil-only emission limit, provided the percentage of fuel oil used is 50% or more on a thermal basis.

Fig. 1 also shows a greater deal of flexibility for those refiners using the bubble concentration reporting method. For a refinery using a bubble limit of 1,000 mg/cu m, this would allow the firing of a 1.5 to 3.0 wt % sulfur fuel oil regardless of thermal capacity, reported Concawe.

For a grassroots refinery (new new plant), however, the bubble limit of 600 mg/cu m would make it difficult to fire any high-sulfur fuels. According to Concawe, the individual reporting case is even more stringent; new new plants of more than 300 MWth could only burn 0.25 wt % sulfur fuel oil.

The revision regarding SOx emission limits will make it difficult for refineries to burn residual fuel oils.

This will demand further investment on the part of EU refiners, especially those in southern Europe, with their dependence on higher sulfur crude sources.

NOx emissions

Fig. 2 shows the impact of NOx emission limits in the revised directive. There is no bubble provision for NOx in the directive, which means that the special majority fuel provision is particularly important, said Concawe.

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The provision will have a significant impact on refiners' fuel-management strategies because maintaining more than 50% fuel oil to individual units has a clear advantage (Fig 2).

According to Concawe, the NOx emission limits will be extremely challenging, especially for high-nitrogen residual fuels and for units that use high levels of combustion-air preheat. In some situations, it may be impossible for some refiners to maintain current levels of air preheat and comply with NOx emissions.

Particulate emissions

Fig. 3 shows emission limits for particulates. Similar to NOx, there is no provision for average bubble concentration. The majority fuel provision provides much needed flexibility, reported Concawe.

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For new new plants, the stringent limit on particulate emissions will seriously restrict the firing of heavy residual fuel oils, especially those with high Conradson Carbon levels.

Concawe reported that complying with both the NOx and particulate emission limits, given the potential of primary control measures, will also be a significant challenge.

New, upgraded plants

The addition of a new unit to an existing refinery will have an ELV based on the thermal rating of the additional plant alone and not the entire site. According to Concawe, this provision will benefit refiners with existing plants.

Another important flexibility in the revised directive is the provision of an alternative approach to upgrading old plants to meet new plant emission limits. Concawe reported that the provision will give refiners a great deal of flexibility in attaining overall site emission targets.

For example, two plants within the same site have new emission targets. The refiner has the flexibility to shut down one plant, upgrade one plant, or upgrade both as long as the combined emissions comply with the site's overall target level.

According to Concawe, this provision will offer a significant potential for optimization within an individual refinery or within a refining company with several refineries in a given country.

Reference

  1. "The revised Large Combustion Plant Directive," Concawe Review, October 2001.