Combustion plant

DSEAR and combustion plant
A very large and diverse range of premises handling materials that make them subject to DSEAR, do so because the flammable material is used on site as fuel.

How does DSEAR apply to combustion plant, what are the risks to employees from such plant? The normal hierarchy of controls set out in DSEAR have to be addressed in a different way from other activities, when the very purpose of the process is to create an explosive fuel-air mixture and ignite it.
These simple questions are not answered for all fuels in a coherent answer in available publications, and they may well be avoided in DSEAR assessments, if the author cannot answer them.

A few examples illustrate the risks
This was a small bakery plant that resulted in a prosecution when it blew up.

High technology premises can get it wrong, and this document from HSE has statistics about fire and explosion incidents with gas turbine plants which provide the power on most offshore oil rigs.

Modern sites often have combined heat and power plants, but you cannot run a hospital without heating. A modest fire delayed the opening of a new hospital by 6 months. As it happened there were no casualties from the fire, but it would have been ironic if the fire had occurred a few weeks later and injured boiler room staff had had to be taken elsewhere after the hospital had opened.

If the main activity on site is not seen as running combustion plant, all too often, when asked, the view from all staff on site can be summed up as ‘ we didn’t install this unit, we don’t maintain it ourselves, we don’t understand how it operates, all we ever do is press the on switch and expect it to fire up faultlessly.‘ It is a little harsh to blame such views if the site operators have bought in a complete package burner with an automated control system, but as users, they do have responsibilities under DSEAR.

Assessing the plant when faced with that response requires an understanding of the basic principles, a knowledge of modern codes and standards from a diverse range of sources, and sound judgement when faced with limited information or old plant. As an HSE inspector dealing with fire and explosion issues, in the days before DSEAR, I used to think assessing combustion plant and systems was the most tricky topic of all. We’ve moved on somewhat since then, but it’s no box ticking exercise.

Gas fired plant
Industrial plant includes AD plants burning low calorific value fuels with a variable composition generated at very low pressures, through to GT plants running on very high pressure natural gas, with a tight gas specification. The gas appliances directive quite specifically excludes industrial plant from its scope. Don’t rely on a CE mark.

Liquid fuelled plant
If you include in this fuels with a boiling range from LPG through to the heaviest crude oil residues, the range of designs is enormous.

Solid fuels , with or without a dust component in the fuel
Bulk coal handling and burning is well understood by the major operators in the power and cement industries, but biomass fuels are generating new problems to be solved.

This page cannot provide all the answers, but only note that:

EN Standards for many components of gas fired plant controls are available, but that may not help if they are unwisely assembled.

Design standards for some but not all types of complete combustion systems are found in national codes.

UK regulations control legal requirements for competence of gas fitters, but just because someone can service a central heating boiler does not make someone competent to service industrial process plant. The legislation is less specific for non- gaseous fuels

Many biomass derived fuels have a rather variable composition, whether they are gases or solids. If you don’t know and can’t control the gas composition, or the amount of dust in a solid fuel, controlling the risks is very difficult.

Make sure your DSEAR assessment does not duck the risks from your combustion plant.