Refractory works refer to the maintenance, repair and refurbishments made to the refractory parts of a biomass or biogas boiler.
Refractory parts are generally found in the combustion and post combustion chambers/zones of a biomass or biogas boiler. The main purpose of refractory material is to contain the heat generated by combustion, the material has a high melting point that maintains it’s structure at very high temperatures.
The most commonly used refractory material used in biomass boilers is fireclay, which is either in brick form or cast into a single solid shape. These elements may also be referred to as a refractory lining.
General maintenance: this should take place during your annual or biannual servicing. A Shaw Renewables boiler service involves a visual inspection and thorough cleaning of fire bricks and the combustion chamber.
Refurbishment and Repair Works: this is dependent on many variables such as boiler make, fuel quality and maintenance. Just like brakes on a car, fire clay wears away during use and will eventually need replacing to ensure safety and efficiency. A good indicator of the lifespan of refractory parts are manufacturer warranties.
If your boiler is undergoing repair works to refractory linings more often than you think is reasonable, contact Shaw Renewables to speak to one of our specialists.
Cracked, chipped and eroded fireclay allows heat to escape the combustion chamber and enter areas of the boiler that are not designed to withstand high temperatures. The heat can cause costly damage to components within the boiler as well as warping of steel work and the outer shell.
Thorough inspection of refractory linings should be undertaken by your maintenance provider during every service to ensure the material isn’t becoming porous and the surface doesn’t show signs of cracking or chips which can reduce your boiler’s efficiency.
An eroding or damaged brick or section of cast fireclay compromises the structural integrity of the entire refractory lining and results in further damage. Taking action to repair fireclay as soon as damage or erosion is visible safeguards against further impairment of the refractory lining.
Whilst the longevity of fireclay is subject to the quality of the materials and processes used by boiler manufacturers, there are some practises that will cause the parts to wear away and crack at an accelerated rate.
Maintenance – When ash residue builds up in the combustion chamber a corrosive slag can form and wear down the refractory lining.
Air Leak – Air leaks reduce boiler output and causes sensors to lower air supply making the combustion chamber hotter – this can cause slag to form which can cause rapid wear of the refractory lining. Damaged seals and combustion chamber doors that do not close correctly are common reasons for air leaks
Unfiltered biomass fuel – foreign objects in fuel, such as nails, screws or stones can damage the walls of the combustion chamber, chipping, pitting and cracking the fire clay.
High moisture content in fuel – whilst quality boiler manufacturers like Froling boast a refractory lining that can handle fuel with a higher moisture content, a dryer fuel will be kinder to all boiler components.
Poor installation – If fireclay parts aren’t fitted correctly warping, corrosion and physical damage can compromise the integrity of the refractory lining and cause issues.
Impact Damage – mishandling fire bricks, using the incorrect cleaning tools or items hitting against the combustion chamber walls can cause damage to fire clay.