Understanding the terminology used by the waste industry can be a little confusing for those new to incineration. We’ve put together a helpful list of typical terms that are commonly used in waste disposal. They are each important to an effective incineration process.
1). Calorific Value of waste
Any type of substance that contains energy has a calorific value. Waste can be burned, because the incineration process harnesses that energy stored within it. Calorific value refers to the heating power of the waste.
Waste can be incinerated without the need for additional fuel when it has a caloric value of 14.4 MJ/kg or higher.
The challenge with calculating the calorific value of waste is that different materials have different calorific values. PVC plastic has a value of 41MJ/kg whereas paper only has a value of 13.5 MJ/kg.
So unless your waste stream is made up of one single material, you’ll need to work out the composition of your waste. Generally speaking, mixed domestic waste will have a calorific value of between 7 and 16 MJ/kg.
| Waste Types | Calorific Value (MJ / kg) | Calorific Value (kCal / kg) |
|---|---|---|
| Medical waste | 18 – 25 | 4530 – 5745 |
| Industrial & hazardous waste | 23 – 39 | 5247 – 9548 |
| Domestic waste (un-processed) | 7 – 16 | 1663 – 3813 |
| Domestic waste (recycled) | 10 – 14 | 2379 – 3335 |
| Plastic (PVC) | 41 | 9787 |
| Wood | 14,4 | 3431 |
| Paper | 13,5 | 3216 |
| Petrol (gasoline) | 45 – 47 | 10583 – 11241 |
| Coal | 15 – 27 | 3594 – 6462 |
| Diesel | 46 | 10982 |
2). Moisture Content of waste
It’s important to know the amount of moisture in your waste, as this can affect how the incineration process works. The less moisture your waste stream contains, the less fuel required for combustion. The moisture content of waste can be calculated by comparing the dry weight with the total weight.
Different types of waste will have different levels of moisture content. Organic waste and food have high moisture content, whereas plastic, glass and metal have very low moisture content.
3). Particle Size of waste
The particle size of waste simply refers to the size of the individual items in your waste stream. This will be dependent on the type of waste you are incinerating.
Municipal Solid Waste could have a range of particles, from small cotton buds to large plastic containers.
The size and shape of particles can affect combustibility rates. They affect how waste material moves across the grate during the combustion process. Some incinerators may have a maximum particle size in order for them to function efficiently. If particle size is too small, some incinerators may not be able to combust them, as they fall through into the ash grate.
4). Standardisation of waste
There are many common types of waste streams, and standardisation refers to a set of averages to ensure the waste mixture remains in roughly the same ratio.
The standardisation of waste can also refer to segregating waste into separate defined streams, so for example, there is a standard paper waste stream, a glass waste stream, and MSW (municipal solid waste) stream and a medical waste stream.
5). Daily Volume
In the incineration process, daily volume refers to the amount an incinerator can safely and efficiently combust during a 24-hour period.
It’s calculated by multiplying the volume of the incinerators combustion chamber (in metres cubed) with the number of operating hours in the day.
6). Waste Brokers & Partnerships
A waste broker is any company or organisation who arranges to recover and dispose of waste for another business, organisation or individual.
Waste brokers will typically collect all types of waste streams, though some may specialise in specific types of waste.
Some businesses may partner with waste brokers if they have a specific type of waste that cannot be easily recycled, combusted or sent to landfill. By mixing this waste with a regular supply of complementary waste, it becomes easier to dispose of.
For example, waste with a high moisture content is hard to incinerate. By mixing this with low moisture content waste from a broker, it’s a lot more efficient & and cost-effective & for the incineration process.
