Glossary
Plain-English definitions of the terms used across this site — drying, fuel specification and process vocabulary, with links to the pages that cover each material in depth.
Process & Measurement
- Moisture content (MC)
- The proportion of a material’s total weight made up of water, given as a percentage. Wet material can be more than half water – freshly harvested wood reaches around 65% moisture, and fresh bark 65%+. Because water adds weight but no energy, moisture content drives nearly every economic factor in biomass: transport cost, calorific value, storage stability and combustion efficiency.
- Wet basis
- Moisture expressed as a share of the material’s total wet weight, rather than of its dry solids alone. The same material gives a different number on each scale, so a moisture figure is ambiguous without its basis. FlowDrya specifications are quoted on a wet basis.
- Calorific value (CV)
- The energy released when a fuel is burned, usually in megajoules per kilogram (MJ/kg). It is the number that determines what a fuel is worth. Drying raises it substantially, because energy that would otherwise evaporate water is delivered as useful heat instead.
- Net calorific value (NCV)
- Calorific value after subtracting the energy consumed evaporating the fuel’s own moisture – the figure that matters commercially, because it reflects the energy a plant actually recovers. RDF typically ranges from 10 to 18 MJ/kg; higher-specification SRF from 15 to 22 MJ/kg.
- Gross calorific value (GCV)
- The total energy released when a fuel burns, including the energy still held in the water vapour it produces. Always higher than the net calorific value, which subtracts that energy. Fuel contracts and the figures quoted on this site use NCV, because that is the energy a plant actually recovers.
- Bulk density
- The weight of a material per unit volume, in kg/m³, including its moisture. It governs transport economics, because hauling wet material means paying to move water. Drying digestate fibre cuts the moisture carried per tonne from roughly 400 kg at 60%+ moisture to around 180 kg below 20%.
- Throughput
- The quantity of material a dryer processes per unit of time. Each FlowDrya is scaled by width and length to meet a project’s throughput requirement rather than sold in fixed sizes.
- Feedstock
- The raw input material fed into a process – a dryer, a pyrolysis reactor, a boiler or a digester. Its moisture, particle size and consistency determine how well the downstream process performs.
- Pyrolysis
- Thermal decomposition of organic material at high temperature with little or no oxygen, producing biochar, oil and gas rather than burning the material. Wet feedstock wastes reactor energy evaporating water instead of converting biomass.
- Biochar
- A stable, carbon-rich solid produced by heating biomass in the near-absence of oxygen. Used for soil improvement and carbon sequestration. Feedstock moisture directly affects both yield and quality, which is why drying precedes pyrolysis.
- Gasification
- Partial oxidation of carbon-rich material at high temperature to produce a combustible gas that can be burned for heat or power. Like pyrolysis, it is sensitive to feedstock moisture.
- Anaerobic digestion (AD)
- Biological breakdown of organic material by micro-organisms without oxygen, producing biogas and a residue called digestate. AD plants are a common FlowDrya application, because the plant’s own process heat can dry the digestate fibre it produces.
- Digestate
- The material remaining after anaerobic digestion. Separating it yields a solid fraction – digestate fibre – which drying converts into a saleable soil improver, peat-free growing medium, animal bedding or solid fuel.Learn more
- Combustion
- Burning fuel in air to release heat. Wet fuel burns at a lower flame temperature and less completely, cutting efficiency and raising emissions per unit of useful energy.
- Trommel
- A rotating cylindrical screen that separates material by particle size, widely used in waste processing. Material that passes through ahead of the main trommel stage is called pre-trommel fines.Learn more
- Screening
- Separating a material stream by particle size. FlowDrya screens heavy inert fines during drying, so drying and screening happen in a single pass.
- Residual heat / waste heat
- Usable heat produced as a by-product of another process – an AD plant, a CHP engine, an industrial exhaust – that would otherwise be wasted. Running a dryer on residual heat is what makes drying economic on many sites.Learn more
- Flue gas
- Hot exhaust gas leaving a combustion process. Its heat can be recovered to supply a dryer rather than being vented to atmosphere.
- Heat exchanger
- A device that transfers heat between two fluids without mixing them, allowing a dirty or otherwise unsuitable heat source to supply clean drying air.
Abbreviations
- MSW
- Municipal Solid Waste – household and commercial waste.Learn more
- CHP
- Combined Heat and Power – generating electricity and usable heat together. A common source of residual heat for drying.
- HMI
- Human-Machine Interface – the operator control screen. FlowDrya’s is the DryStation™ panel.
- CBD
- Cannabidiol – a hemp compound preserved by low-temperature drying.Learn more
- BSF
- Black Soldier Fly – the insect species whose farming produces frass.Learn more
FlowDrya Technology
- FlowDrya
- Stronga’s continuous industrial drying system, built around a hydraulic moving floor rather than a belt. Each unit is custom-engineered to the customer’s material, throughput and heat source. Available as the Green Series for biomass and organic materials, and the International Series for heavy-duty industrial waste.Learn more
- PulseWave™ agitation
- FlowDrya’s material-agitation system. It keeps the bed moving during drying so air passes evenly through it, giving consistent moisture without the belts or chains that fibrous materials wrap around.
- DryStation™
- FlowDrya’s control system and operator interface: intelligent, robust and straightforward to use, holding the required moisture parameters consistently rather than needing manual adjustment.
- Heatex
- Stronga’s air-handling unit. It takes heat from whatever source a site has – residual process heat, LPG or gas-fired burners – and delivers drying-quality air to the FlowDrya, decoupling the dryer from any single heat source.Learn more
- Moving floor
- The hydraulic mechanism that conveys material through a FlowDrya. Having no belts or chains removes the wear parts and wrap-around failures common to belt dryers.
- Deep-cycle drying
- Drying a deep bed of material in a single pass rather than a thin layer, raising throughput for a given machine footprint. FlowDrya achieves bed depths of 500–600 mm on RDF.Learn more
Materials & Fuels
- SRF – Solid Recovered Fuel
- A waste-derived fuel produced to a specification, used chiefly by cement kilns as an alternative to fossil fuel.Learn more
- RDF – Refuse Derived Fuel
- A waste-derived fuel for energy recovery, generally to a lower specification than SRF.Learn more
- Digestate fibre
- The solid fraction separated from digestate after anaerobic digestion.Learn more
- Wood chip
- Woody biomass mechanically chipped for fuel or processing.Learn more
- Bark
- The outer covering of trees, a sawmill by-product used as fuel, mulch or growing media.Learn more
- Forestry brash
- Branches and residues left after felling, chipped for boiler fuel.Learn more
- Insect frass
- The by-product of insect farming, used as an organic fertiliser.Learn more
- Brewer’s grains
- Spent grain left after brewing, dried for animal feed and food ingredients.Learn more
- Waste fines
- The fine fraction screened from a waste stream.Learn more
- De-packaging waste
- Plastic packaging separated from food waste ahead of anaerobic digestion.Learn more
- Poultry manure
- Litter and manure from poultry housing, dried into a bio-fertiliser.Learn more
Standards
- EN ISO 17225
- The international standard specifying fuel classes for solid biofuels. Part 4 covers wood chips, classifying them by properties including moisture, ash content and particle size, so buyer and seller can describe the same fuel unambiguously.
- EN ISO 21640
- The standard classifying solid recovered fuel by net calorific value, chlorine content and mercury content, each banded into five classes rather than judged against a single pass mark. Class 1 requires a mean NCV of at least 25 MJ/kg, Class 2 at least 20, Class 3 at least 15, Class 4 at least 10 and Class 5 at least 3.Learn more