In the guide below, we outline the different types and methods of waste incineration.
We categorise these different types and methods of waste incineration by waste type, incinerator technology & plant design, incinerator features, and more.
Firstly, What Is Waste Incineration?
In the most basic sense, waste incineration is the thermal treatment of waste.
According to eolss.net: ‘Incineration is a method of thermally reducing the volume of combustible waste …’
According to wikipedia.org: ‘Incineration is a waste treatment process that involves the combustion of substances contained in waste materials’
Secondly, What Is Waste-To-Energy Incineration?
What Waste-To-Energy Incineration Is
Some of the main by-products of waste incineration (i.e. what the waste is converted into) are ash, flue gas, and heat.
Some plants are waste-to-energy plants, and these plants can use heat to generate electricity.
For example, the heat may heat up water, which produces steam, and the steam powers turbines to generate electricity.
Waste-To-Energy Incineration vs Other Waste To Energy Processes
aph.gov.au mentions that waste to energy incineration is one of a range of waste to energy processes. Gasification, pyrolysis and plasma arc technologies are other thermal processes, whilst there are biological processes as well, and methane can also be captured from landfill.
wikipedia.org outlines the different between incineration and gasification technologies:
While incineration and gasification technologies are similar in principle, the energy produced from incineration is high-temperature heat whereas combustible gas is often the main energy product from gasification.
Incineration and gasification may also be implemented without energy and materials recovery
Different Types & Methods Of Incineration
The different ways to categorise different types and methods of incineration might include:
– By the incinerator technology, design, features, or application
– By the type of waste being treated
We discuss some of these points in the guide below.
Different Incinerators, Different Incinerator Technologies, & Different Plant Designs
Different Types Of Incinerators, Incinerator Technology, & Plant Designs
Different incinerators (also called furnaces) use different technologies and incinerator plant designs for the combustion of different types of waste.
eolss.net also mentions that different incinerator furnace types can be categorised according to their application.
Some of the different incinerator technologies and plant designs are:
– Moving Grate Incinerators
According to both wikipedia.org, and bioenergyconsult.com, the most common incinerator for municipal solid waste is a moving grate incinerator
Moving grate incinerators are sometimes referred to as ‘Municipal Solid Waste Incinerators’ for this reason
The ability of the grate to move helps move the waste inside the combustion chamber, which in turn helps optimize more efficient and complete combustion of the waste
– Fixed Grate Incinerators
An older and simpler incinerator than the moving grate incinerator
It has a fixed metal grate instead of a moving one
– Rotary Kiln Incinerators
An incinerator used by municipalities and by large industrial plants
Rotary kiln incinerators have a primary chamber and a secondary chamber
The way different rotary kiln incinerators work might differ slightly (depending on the incinerator machinery, and who it’s designed by), but in general, the primary combustion chamber accepts the waste and converts it from it’s original form to gas form, and passes it onto the secondary chamber which completes the gas combustion process
The primary chamber usually rotates, either to move the waste or to make burning easier, or both. The secondary chamber can be static.
verantis.com mentions that ‘Rotary kiln incineration systems are ideal for processing mixed industrial and hazardous wastes that include a combination of solids, sludge, and liquids’. eolss.net mentions they are for industrial waste
And, feeco.com mentions that ‘Rotary kiln incinerators are becoming increasingly more widespread, as the incineration industry evolves to handle more complex and diverse waste streams’
– Fluidized Bed Incinerators
A fluidized bed involves creating a ‘fluidized bed’ of sand (or other granular material), and pre-heated air inside a furnace
The air is blown at a speed that keeps the sand floating/suspended
Waste (and sometimes fuel) is added to the furnace, and heat is transferred to the waste to incinerate it
industrialfurnace.com and eolss.net indicate that fluidized bed incinerators are for municipal sludge and general sewage sludge, whilst scienedirect.com, indaver.com, and chavond-barry.com say they are for industrial waste and sludge
– Multiple Hearth Furnaces
MHF’s consist of a series of hearths
Several reports indicate that multiple hearth furnaces are for the treatment/incineration of wastewater biosolids and sewage sludge
The sludge is treated as it falls through to each lower hearth in the MHF shell
– Shaft Furnaces
There can be different types of shaft furnaces
For example, metallurgical shaft furnaces may deal with municipal solid waste, whilst vertical shaft furnaces also exist
Shaft furnaces that deal with specialty waste like radioactive waste may also be in the design stage
– Specialised Incinerators
Both wikipedia.org and science.jrank.org mention that more specialized incinerators can incinerate hazardous waste
Waste from hospitals, waste from research facilities, and toxic and chemical wastes are all examples of waste that may be incinerated with a specialised incinerator
– Other Forms Of Incineration
Other forms of incineration that might be simpler and not involve the use of engineered incinerator plant machinery include:
Burn Pile Incineration – an open mound of waste that is set on fire. A simple and early form of incineration.
Burn Barrel Incineration – waste is burned inside a metal barrel with metal grating over the exhaust
Pros & Cons Of Different Types Of Incinerators
There can be different pros and cons for the different incinerators.
bioenergyconsult.com lists some of the benefits of moving grate incinerator for example, such as not needing to sort mixed waste before putting it in a moving grate incinerator, being able to process large quantities of waste, and perhaps being one of the most efficient and cheapest forms of large scale incineration
bioenergyconsult.com also mentions that ‘Compared to other waste to energy technologies … like gasification and pyrolysis technologies … [moving grate incineration isn’t as limited] in scale, [or] in material for industrial/hazardous waste treatment, [and it doesn’t require] preprocessing of mixd MSW before feeding.
In addition to these benefits, moving grate incinerators can recover energy for electricity, and may be suitable for developing countries too.
Features That Can Differ Between Incinerators
Different incinerators also have different technology and devices for:
– The use of heat
– Mitigating and managing pollution (such as flue gas cleaning)
– Gaseous emissions that can impact human health (dioxins and furans)
– Solid outputs, and solid waste material left over from combustion
Other features and methods that can differ between different incinerators can include:
– Incinerator size, plant capacity (the amount of waste that can be incinerated, or the rate of incineration), operating schedule (continuous, or separate shift schedules), dry or wet methods of ash extraction, the method of exposing burning material to combustion air fuel requirements, emission rate, and more
Different Combustion Methods, & Different Combustion Systms
eolss.net also mentions that there is submerged combustion, and vortex combustion to consider
tske.co.jp mentions that submerged combustion systems are for various types of liquid waste discharged from production processes
Vortex combustion is a system for waste-to-energy conversion that might use a cyclonic thermal process, or a vortex combustion chamber
Incineration By Waste Type
Incineration can also be categorised by the type of waste being incinerated.
These different types of waste may go to different incinerator sites, or different incinerators on the same site.
There might be two main ways to group the different waste types:
First Way To Group Different Waste Types
The first way to group waste types might be by the type of waste stream.
The different waste streams might include:
– Municipal Solid Waste
– Commercial & Industrial Waste
– Hazardous Waste
– Special Waste, such as Medical Waste
Second Way To Group Different Waste Types
The second way to group waste types might be by the traits/properties of the waste.
The different waste types by traits/properties might include:
– Solid Waste
– Gaseous Waste
– Liquid Waste (& Sludge Waste)
eolss.net groups gases and liquids together, and solid waste by itself
Potential Pros & Cons Of Waste Incineration
We outline some of the potential pros and cons of waste incineration in this guide.