Difference Between Incineration and Pyrolysis

Key Difference – Incineration vs Pyrolysis
 

Both incineration and pyrolysis are forms of combustion, the thermal decomposition of matter. They differ from each other based on the requirement of oxygen for the combustion process. The key difference between incineration and pyrolysis is that incineration is the combustion of organic matter in the presence of oxygen whereas pyrolysis is the combustion of organic matter in the absence of oxygen.

CONTENTS

1. Overview and Key Difference
2. What is Incineration
3. What is Pyrolysis
4. Similarities Between Incineration and Pyrolysis
5. Side by Side Comparison – Incineration vs Pyrolysis in Tabular Form
6. Summary

What is Incineration?

Incineration is the combustion of organic matter in the presence of oxygen. It is one of the major ways of destroying waste materials. It is a type of thermal treatment carried at very high temperature. The incineration process converts waste into ash, gases (flue gas) and heat. The heat generated from this treatment can be used to generate electricity.

Incinerators are used in large-scale incineration processes. Earliest incinerators had no steps of material separation to separate materials that are hazardous, bulky or recyclable. Modern incinerators are more advanced and make use of all useful matter included in waste. These incinerators have pollution mitigation equipment (for flue gas cleaning). Modern incinerators reduce the mass of waste by 80%. The volume is reduced by around 95%.

There are several methods of carrying out the incineration process:

1. Burn pile – includes burning combustible material piles on the ground in an open area.
2. Burn barrel – the combustible material is placed inside a metal barrel and is burnt. This method avoids the spread of burning materials and the ash produced at the end of the incineration settle down to the bottom of the barrel.
3. Rotary-kiln – A rotary-kiln is a type of incinerator. These incinerators are used in industrial scale applications. It has more equipment, and the incineration process is more advanced and complicated.
4. Fluidized bed – this method includes passing heated air through a sand bed until a fluidized bed condition is created. Then the waste particles are introduced into this fluidized bed.
5. Moving grate – this is the typical type of incinerator used in municipal waste management processes. The combustion is more efficient and is a complete

Disadvantages of incineration include followings:

• Incineration reduces the recycling of recyclable materials because burning is easier and cheaper than recycling.
• Incineration releases gaseous components such as carbon dioxide (CO2).
• Incineration emits hazardous end products.
• Incineration can lead to different health risks.

What is Pyrolysis?

Pyrolysis is the combustion of organic matter in the absence of oxygen. This is a thermal decomposition carried out in an inert atmosphere such as in the presence of vacuum gas. The chemical composition of the material is changed by this process, and the process is irreversible.

Generally, pyrolysis of organic materials causes the production of volatile components along with a carbon-containing solid residue and tar. This process gives end products in solid phase, liquid phase and gas phase as well. The pyrolysis is done at temperatures above 430°C. Carbonization is a form of pyrolysis which leaves a solid residue rich with carbon.

Uses of pyrolysis are as follows:

1. Ethylene production
2. Production of tar
3. Production of biofuels from biomass.

What are the Similarities Between Incineration and Pyrolysis?

• Both incineration and pyrolysis include burning of materials.
• Both processes produce gaseous compounds as end products.

What is the Difference Between Incineration and Pyrolysis?

Summary – Incineration vs Pyrolysis

Incineration and pyrolysis are thermal decomposition methods. The key difference between incineration and pyrolysis is that incineration is the combustion of organic matter in the presence of oxygen whereas pyrolysis is the combustion of organic matter in the absence of oxygen.

Reference:

1. “Incineration .” Everythingconnects.org, Available here.
2. “Incineration.” Wikipedia, Wikimedia Foundation, 3 Apr. 2018, Available here.
3. “Pyrolysis.” Wikipedia, Wikimedia Foundation, 4 Apr. 2018, Available here.

Image Courtesy:

1. “Beitou Refuse Incineration Plant 20090830” By 玄史生 – Own work (CC BY-SA 3.0) via Commons Wikimedia
2. “TyrePyrolysisplant” By Zzkysb – Diagram make for our customer (CC BY-SA 3.0) via Commons Wikimedia