Glossary
Terms commonly used in the pyrolysis process.
Pyrolysis: A fundamental thermochemical process where organic materials are heated to high temperatures (typically 300-800°C) in the absence of oxygen. This controlled heating causes the materials to break down into smaller, more valuable products: a solid (char), a liquid (bio-oil/pyrolysis oil), and a gas (syngas). It's essentially "cooking" materials without burning them.
Types of Pyrolysis
Fast Pyrolysis: Characterized by rapid heating rates and short residence times (seconds), primarily designed to maximize the production of liquid bio-oil.
Flash Pyrolysis: An even more rapid process than fast pyrolysis, with extremely high heating rates and very short residence times (milliseconds), often aiming for a high yield of gas products.
Intermediate Pyrolysis: Operates at conditions between slow and fast pyrolysis, with moderate heating rates and residence times.
Microwave-Assisted Pyrolysis (MAP): Utilizes microwave radiation as the heating source, offering advantages like rapid and uniform internal heating, precise control over reaction conditions, and potential for higher product yields compared to conventional heating methods.
Slow Pyrolysis (also called Conventional Pyrolysis or Carbonization): Involves slower heating rates and longer residence times (minutes to hours), primarily designed to maximize the production of solid biochar/charcoal.
Equipment & Environment
Condenser: A heat exchanger specifically designed to cool the hot vapor products exiting the pyrolysis reactor, causing them to condense into the liquid form known as bio-oil or pyrolysis oil.
Hoppers: Large, funnel-shaped containers used for temporarily holding and then gravity-feeding bulk solid materials (like shredded plastics, wood chips) into a processing system or feeder.
Inert Atmosphere: The essential oxygen-free environment within the reactor.
Loaders: Heavy machinery (e.g., front-end loaders, skid steers) used to move and load large volumes of raw feedstock (like tire bales, large piles of biomass) into hoppers or pre-processing equipment.
Reactor: The sealed central vessel where the pyrolysis process takes place. Its design is critical and depends on the type of pyrolysis and feedstock.
Tire Cutters (or Shredders): Equipment used to mechanically reduce the size of whole tires into smaller, more manageable pieces (shreds or chips) before they can be fed into a pyrolysis reactor.
Tire Nestlers (or Balers): Equipment that compresses and bundles whole tires into dense, compact units or "nests." This helps in more efficient storage and transportation of scrap tires before processing.
Waste Oil Burners: Specialized burners designed to combust liquid fuels derived from waste streams, such as pyrolysis oil (TPO, PPO), to generate heat for the pyrolysis reactor or other industrial processes, making the operation more self-sufficient.
Wet Scrubber: An air pollution control device that uses a liquid (often water or a chemical solution) to remove pollutants (like acid gases, particulate matter, or odors) from the exhaust gas stream of the pyrolysis plant before it is released into the atmosphere.
Feedstocks (Inputs) - Expanded Examples
Agricultural Residues: Crop stalks (corn stover, wheat straw), rice husks, bagasse (sugarcane residue), nut shells.
Biomass: Organic matter derived from recently living organisms, primarily plants.
Dedicated Energy Crops: Plants grown specifically for energy production, like switchgrass or miscanthus.
End-of-Life Tires (ELTs): Waste or scrap tires that are no longer suitable for their original use or retreading, representing a significant waste stream globally.
Industrial Sludges: Such as oil sludge from refineries or sewage sludge from wastewater treatment plants.
Mixed Plastics: Collections of various plastic types, often from municipal solid waste, requiring sorting before pyrolysis.
Municipal Solid Waste (MSW): The organic fraction of household and commercial waste, excluding recyclables and hazardous materials.
Plastic Waste: Various synthetic polymers discarded after use.
Polyethylene (PE): Common in rigid containers (milk jugs - HDPE), and flexible films (plastic bags, cling wrap - LDPE).
Polypropylene (PP): Used in bottle caps, yogurt containers, car bumpers, and some carpets.
Polystyrene (PS): Found in disposable foam cups, food trays, and rigid plastic cutlery.
Woody Biomass: Wood chips, sawdust, forest thinning’s, branches, storm debris
Byproducts (Outputs) – Expanded Examples
Biochar: A specific type of carbon char produced exclusively from biomass pyrolysis. It is a stable, porous, carbon-rich solid. Primarily used as a soil amendment to improve soil fertility, water retention, and enhance carbon sequestration (locking carbon in the soil). Also used in water filtration and as a lightweight aggregate.
Carbon Char: The general term for the solid, carbon-rich residue remaining after the pyrolysis of any organic material. It represents the non-volatile portion of the feedstock after thermal decomposition. Can be used as a low-grade fuel or further processed and refined into specific products like biochar or recovered carbon black.
Plastic Pyrolysis Oil (PPO): The liquid product specifically obtained from the pyrolysis of waste plastics. Its composition varies widely based on the type of plastic feedstock (e.g., PE, PP, PS) and process conditions. Generally, a complex mixture of hydrocarbons with a high calorific value, often resembling crude oil or diesel. It typically has a lower sulfur content than traditional fossil fuels. Can be used as a fuel for industrial heating (e.g., in cement kilns, power plants) or, more importantly, as a valuable feedstock for producing new plastics and chemicals through refinery processes.
Pyrolysis Oil (Bio-oil, Biocrude, Py-oil): A dark brown, often viscous liquid produced from the rapid cooling and condensation of the vapor phase during pyrolysis. Can be used as a direct fuel for industrial heating (e.g., boilers, furnaces) or, after upgrading and refining, as a feedstock for producing transport fuels or specialty chemicals.
Recovered Carbon Black (rCB): The solid, carbonaceous residue (a refined form of carbon char) specifically obtained from the pyrolysis of End-of-Life Tires (ELTs) and other rubber products. It undergoes further processing (e.g., magnetic separation for steel, grinding, and sometimes chemical treatment) to enhance its quality. Primarily used as a sustainable reinforcing filler or pigment in new rubber products, plastics, inks, coatings, and asphalt.
Recovered Metals (e.g., Steel Wire): Metallic components (like steel belts and beads from tires) that remain in the solid residue after pyrolysis. They are typically separated magnetically from the carbon char. Can be recycled as raw material in the steel and metal industries.
Syngas (Producer Gas, Pyrolysis Gas, Non-condensable Gases): A gaseous mixture that remains after the condensable vapors have been collected. It's primarily composed of combustible gases like carbon monoxide (CO), hydrogen (H₂), methane (CH₄), along with non-combustible carbon dioxide (CO₂) and some nitrogen (N2) if an inert purge gas is used. Has a significant energy content. Can be directly combusted to provide heat for the pyrolysis process itself (making it self-sustaining), used to generate electricity (e.g., in gas engines or turbines), or purified and used as a chemical feedstock for producing hydrogen, methanol, or other synthetic fuels via processes like Fischer-Tropsch synthesis.
Tire Pyrolysis Oil (TPO): The liquid product obtained from the pyrolysis of End-of-Life Tires (ELTs). A dark liquid with a high calorific value, comparable to diesel or fuel oil. It contains a complex mix of hydrocarbons, including aromatics (like benzene, toluene, xylene) and limonene. TPO generally has a higher sulfur content than plastic pyrolysis oil due to the sulfur used in tire vulcanization. Commonly used as a fuel for industrial boilers, marine engines, or for power generation. It also holds potential as a source of valuable chemicals after refining.