Pellet Analysis

Pellet fuel is a renewable, clean-burning, and cost-effective home heating alternative. It is a biomass product made from renewable materials (usually recycled wood waste). Many homes use wood pellets for heating in freestanding stoves, fireplace inserts, furnaces, and boilers. Pellet fuel is also used in large-scale settings such as schools and prisons. Pellets are made in manufacturing facilities and sold at fireplace dealers, nurseries, building supply stores, and feed and garden supply stores. In short, pellet fuel is a way to turn millions of tons of waste into energy by diverting it from landfills.

Examples of biomass fuels include wood, wood pellets, wood chips, waste paper, and a multitude of other agricultural products and byproducts that can be used for energy. The most basic principle of biomass is that it is renewable. The remarkable consistency and combustion efficiency of pellet fuel produces a fraction of the particulate emissions of raw biomass. Pellet burners have the lowest particulate matter emissions of all solid fuel burners. Given proper sustainable forestry initiatives and agricultural management, biomass is virtually limitless and relatively stable in price compared to fossil fuels.

Many pellet producers take byproducts such as wood waste and turn them into pencil-sized pellets that are uniform in size, shape, moisture, density and energy content. Raw biomass is not burned directly because the moisture content of raw biomass is between 20 percent and 60 percent. Pellets, however, have a significantly lower moisture content (4 percent to 8 percent water). Pellet fuel also has a significantly higher density than raw biomass. More fuel can be transported in a given truck space, and more energy can be stored on site. Meanwhile, pellets are easier and more predictable to handle. Their uniform shape and size allow for a smaller, simpler feed system that reduces costs. This high density and uniform shape can be stored in standard silos, transported on railcars and delivered in truck containers.

Pellet analysis in the context of fuels generally refers to the examination and testing of fuel pellets, such as those made from biomass, wood or nuclear material, to assess their quality, composition and performance characteristics. There are two key concepts involved:

• Biomass/wood fuel pellet analysis: Used in heating systems, stoves or power plants. The analysis includes the following basic parameters:
  • Moisture content: Affects combustion efficiency.
  • Ash content (too much): Means more residue and maintenance.
  • Calorific value (energy content): How much energy the pellet releases.
  • Bulk density: Affects storage and transportation.
  • Durability: How easily the pellets break or produce dust
  • Chlorine/sulfur content: Too much can corrode equipment.

In these analyses, the standard “ISO 17225-2 Solid biofuels - Fuel properties and classes - Part 2: Graded wood pellets” is used as a basis. This standard describes the fuel quality classes and properties of graded wood pellets for industrial and non-industrial uses. This standard covers only wood pellets produced from the following raw materials:

• Forest, plantation and other virgin wood
• By-products and residues from the wood processing industry
• Used wood that has not been chemically treated

Heat-treated biomass pellets (e.g. torrefied pellets) are not included in the scope of this standard.

• Nuclear fuel pellet analysis: In nuclear energy, fuel pellets are usually obtained from uranium dioxide and used in fuel rods for reactors. The analysis includes the following key parameters:
  • Pellet density and porosity: Affects how much fuel will fit on a rod and how it will behave under pressure.
  • Grain size, surface defects and microstructure: Grain size, cracks, defects and the like.
  • Chemical composition and enrichment: Especially for enriched uranium.
  • Fission gas release (post-irradiation): Tests how gases such as xenon and krypton escape during use.
  • Thermal conductivity: Affects how heat is transferred.

These tests are usually performed in highly controlled laboratories after irradiation in hot cells with robotic instruments.

International standards used in pellet analysis include, but are not limited to, the following:

• ISO 17225-2 Solid biofuels - Fuel properties and classes - Part 2: Graded wood pellets
• ASTM C776-17 Standard Specification for Sintered Uranium Dioxide Pellets for Light Water Reactors. This standard applies to finished sintered uranium dioxide pellets. It applies to uranium dioxide pellets containing any 235U concentration of uranium for use in nuclear reactors. This standard recognizes the presence of reprocessed uranium in the fuel cycle and therefore defines isotopic limits for uranium dioxide pellets made from commercial grade uranium dioxide. Such commercial grade uranium dioxide is defined so that the product is essentially equivalent to that made from unirradiated uranium for purposes of fuel design and manufacture. Uranium dioxide falling outside these limits is not necessarily considered equivalent and therefore may require special provisions in the fuel manufacturing facility or fuel design.
• ASTM C759-10 Standard test methods for chemical, mass spectrometric, spectrochemical, nuclear, and radiochemical analysis of nuclear-grade plutonium nitrate solutions (Guide for nuclear fuel pellet inspection). This standard describes procedures for chemical, mass spectrometric, spectrochemical, nuclear, and radiochemical analysis of nuclear-grade plutonium nitrate solutions to determine compliance with specifications.
• ASTM C1674-16 Standard test method for flexural strength of advanced ceramics with engineered porosity (honeycomb cellular channels) at ambient temperatures (Microstructure evaluation for sintered uranium dioxide pellets). This standard describes a test method for determining the flexural strength (flexural modulus of rupture) of advanced ceramic structures with a two-dimensional honeycomb channel architecture at ambient conditions.

Our organization, which has been trying to support businesses from every sector with its testing, measurement, analysis and evaluation studies carried out in a wide range for years, has a strong staff that closely follows the developments in the world in the field of science and technology and constantly improves itself. In this context, pellet analysis services are also provided to businesses.