What is waste combustion?
Image 3: Fire Bin
Waste combustion, also known as incineration, is a method of treating waste via confined and controlled burning. This method reduces the solid mass of the waste by 80-85% and its volume by 95%, which helps significantly reduce the need for landfills and the reliance on fossil fuels. Energy recovery through waste combustions is part of the waste-to-energy (WTE) technologies. WTE is a process whereby energy is generated from waste treatment. This energy generated can be either in the form of electricity or heat.
WTE process can either produce energy through combustion or produce combustible fuels commodity. Some examples of combustible fuel commodities are methane, ethanol and synthetic fuels. WTE uses solid waste (a.k.a. shit or poop) generated by people. WTE is a crucial process in maintaining a sustainable waste management framework.
However, incineration is the only process that works via combustion. There are various types of incineration, namely mass burn combustion, and refused derived fuel (RDF) combustion. Mass burn combustion is the most common form of incineration whereas RDF combustion is more complicated as it requires separation of non-combustible materials such as glass and metals before burning. Hence in this discussion, we will explore mass burn combustion in greater detail.
How is waste processed? Incineration.
Image 5: Senoko Incineration plant – Waste to Energy
Mass burn combustion takes place in a mass burn facility which is a type of municipal solid waste (MSW) incineration facility. They are large facilities that contain the waste which will be burnt at high temperature. Firstly, the MSW must be burned to remove the large and non-combustible items as well as the hazardous or explosives waste. Thereafter comes the sorting process. The smaller-sized waste will be shredded to a size of less than 6 inches, then transferred into the incinerator where temperatures range between 800 to 1000 degrees Celcius.
Air will be supplied from either above or below the grate to promote combustion. Water will be supplied along the walls of the boiler and converted into steam which will be used to drive the turbines to produce energy. When all the waste has been burned, what remains is the bottom ash which is further processed to ensure all metals are removed. The gas produced via combustion, known as combustion gas, will be transferred into a scrubber to be chemically treated, removing any hazardous components such as sulphur dioxide. A large proportion of gas will be converted into water and salt. The remaining amount of gas and fly ash will then pass into the baghouse where ash is filtered out and removed.
Lastly, the gas will pass through a smokestack to reduce the amount of pollutants released into the atmosphere while the fly ash will be collected and deposited at a landfill.
Mass burn combustion plants have the capacity to process anywhere from 20,000 kilograms to 2,700,000 kilograms of MSW per day. In the United States, this process can produce 65 megawatts of power which is equivalent to providing electricity to power approximately 65,000 homes!
References:
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- Darling, D. (2017). refuse-derived fuel (RDF). Daviddarling.info. Retrieved 1 April 2017, from http://www.daviddarling.info/encyclopedia/R/AE_refuse-derived_fuel.html
- Energy Recovery from the Combustion of Municipal Solid Waste (MSW) | Sustainable Materials Management | US EPA. (2017). Epa.gov. Retrieved 1 April 2017, from https://www.epa.gov/smm/energy-recovery-combustion-municipal-solid-waste-msw#Technologyhttp://www.scottmadden.com/wp-content/uploads/userFiles/misc/d3e7622ce7883b847500fca105075250.pdf
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- Mass Burn Incinerators: Definition and Issues – Video & Lesson Transcript | Study.com. (2017). Study.com. Retrieved 1 April 2017, from http://study.com/academy/lesson/mass-burn-incinerators-definition-and-issues.html
- Waste To Energy – How to Produce Energy From Garbage and Waste – Conserve Energy Future. (2017). Conserve Energy Future. Retrieved 1 April 2017, from http://www.conserve-energy-future.com/waste-to-energy.php
- Waste-to-Energy: How It Works – Deltaway Energy. (2017). Deltawayenergy.com. Retrieved 1 April 2017, from http://www.deltawayenergy.com/wte-tools/wte-anatomy/
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