In a feed mill, a steam boiler generates the steam used primarily for conditioning mash before pelleting, where heat and moisture from steam soften the feed mixture, gelatinize starches and improve binding, resulting in higher pellet durability, increased throughput and reduced energy consumption at the pellet mill itself. As a general guide, a pellet mill processing 1.0–1.5 tonnes per hour typically requires a boiler capable of generating in the region of 100 kg of steam per hour, though actual requirements depend on conditioning temperature targets, moisture addition rates and the specific formulation being processed.

Feed mill boilers are most commonly fired by natural gas, fuel oil, biomass or coal depending on regional fuel availability and cost, and must be sized not only for the average steam demand of the conditioning process but for peak demand during start-up or when processing particularly dense or hard-to-condition formulations.

Boiler types used in feed mills range from simple fire-tube designs, where hot combustion gases pass through tubes submerged in a water-filled shell to generate steam, to more sophisticated water-tube designs typically reserved for larger installations with higher steam demand; fire-tube boilers are by far the more common choice in small to mid-sized feed mill applications due to their lower cost and simpler operation.

Boiler efficiency, water treatment to prevent scale build-up, and steam pressure regulation all directly affect conditioning performance downstream — inconsistent or insufficient steam supply is a common root cause of variable pellet quality in mills experiencing conditioning problems, making boiler performance monitoring an indirect but important part of overall pellet quality management.

Water treatment deserves particular attention, since untreated feed water containing dissolved minerals will gradually deposit scale on internal boiler surfaces, reducing heat transfer efficiency and, in severe cases, posing a safety risk by allowing localized overheating of boiler tubes or shell sections that scale has insulated from proper water contact.

Regulatory inspection and certification requirements for pressure vessels typically apply to feed mill steam boilers in most jurisdictions, given the inherent safety risks of pressurized steam generation equipment, making boiler maintenance, inspection scheduling and operator training a compliance matter as well as an operational and pellet-quality consideration.