Pyrolysis is a versatile thermochemical process for converting biomass, plastics, and waste materials into valuable energy products like biochar, bio-oil, and syngas. The operational parameters, feedstock characteristics, reactor design, and pyrolysis type significantly influence product yields and quality. Advances in pyrolysis technology continue to drive innovation in renewable energy production and waste valorization, contributing to sustainable and environmentally friendly energy solutions.

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PYROLYSIS – ITS PRINCIPLES
AND TYPES
By
Er. T. AYISHA NAZIBA, Dr. D. RAMESH, Dr. S. PUGALENDHI

2. Pyrolysis
• Pyrolysis is a thermal decomposition process that breaks down organic materials (such as
biomass, plastics, or waste) in the absence of oxygen at elevated temperatures. This process
results in the production of char (solid residue), bio-oil (liquid product), and syngas (gaseous
product). Pyrolysis is a key thermochemical conversion method for transforming biomass and
waste materials into valuable energy products.

3. Operational Parameters
• Temperature:
• Pyrolysis is typically conducted at temperatures ranging from 300°C to 800°C or higher.
• Higher temperatures generally result in faster reaction rates and can influence product distribution.
• Heating Rate:
• The rate at which the material is heated affects the pyrolysis process and product yields.
• Controlled heating rates are important to optimize product quality and energy efficiency.
• Residence Time:
• Residence time refers to the duration that the material remains at the pyrolysis temperature.
• Longer residence times can promote further decomposition but may also lead to undesirable side
reactions.

4. Products of Pyrolysis
• Biochar (Solid Residue):
• Biochar is a carbon-rich solid residue produced from the pyrolysis of
biomass.
• It is used as a soil amendment to enhance soil fertility and carbon
sequestration.
• Bio-oil (Liquid Product):
• Bio-oil, also known as pyrolysis oil or bio-crude, is a dark liquid
composed of various organic compounds.
• It can be further processed into fuels or chemicals through upgrading
processes.
• Syngas (Gaseous Product):
• Syngas is a mixture of hydrogen (H2), carbon monoxide (CO), methane
(CH4), and other gases.
• Syngas can be used for heat and power generation or converted into
fuels like hydrogen or synthetic natural gas (SNG).

5. Factors Affecting Pyrolysis
• Feedstock Composition:
• The type and composition of the feedstock (e.g., biomass species, plastic type) influence pyrolysis
product yields and properties.
• Temperature and Heating Rate:
• Operating temperatures and heating rates affect the distribution of pyrolysis products and the quality of
bio-oil.
• Residence Time and Reactor Design:
• The residence time in the reactor and reactor design (e.g., fixed-bed, fluidized bed) impact the extent of
pyrolysis reactions.
• Catalysts and Additives:
• Catalysts or additives can be used to enhance pyrolysis performance, modify product distribution, and
reduce tar formation.

6. Types of Pyrolysis
• Slow Pyrolysis:
• Slow pyrolysis involves heating biomass at low temperatures (300°C to 500°C) with limited oxygen supply.
• It produces biochar as the primary product, along with bio-oil and syngas.
• Fast Pyrolysis:
• Fast pyrolysis operates at higher temperatures (500°C to 800°C) and shorter residence times.
• It maximizes bio-oil production, with lesser amounts of biochar and syngas.
• Flash Pyrolysis:
• Flash pyrolysis is a rapid heating process conducted at very high temperatures (above 800°C) and short
residence times.
• It primarily produces bio-oil with minimal biochar and syngas.

7. Pyrolyzers
• Fixed-Bed Pyrolyzers:
• Fixed-bed pyrolyzers use a stationary bed of feedstock material heated from the bottom to promote
thermal decomposition.
• Fluidized Bed Pyrolyzers:
• Fluidized bed pyrolyzers suspend feedstock particles in a hot gas stream, enhancing heat transfer and
reaction rates.
• Rotary Kiln Pyrolyzers:
• Rotary kiln pyrolyzers rotate cylindrical vessels to mix and heat feedstock materials, facilitating uniform
pyrolysis.

8. Fixed bed pyrolyzer

9. Fluidized Bed Pyrolyzers

10. Rotary Kiln Pyrolyzers

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