Moisture Content
Moisture Content is generally used as a key component to describe the water present in WDF which in turn affects the quality and energy content of the WDF. The impact on the energy value or NCV is a key factor in determining the ability of an EfW facility being able to receive the material and the Gate Fee that is charged[1].
The heating value of the fuel or NCV decreases with increased Moisture Content, in simple terms the higher the moisture the lower the NCV. In addition, Moisture Content is an important parameter as: higher Moisture Content increases the volume of Flue Gas produced per energy unit, requiring larger waste heat boilers and Flue Gas cleaning equipment;
- high Moisture Content will reduce the combustion temperature, changing the combustion properties which may in turn lead to in higher emissions if the combustion cannot be appropriately adjusted
- it will influence the behaviour of the waste during the primary conversion stage in a Gasification/Pyrolysis plant and will also impact on the properties and quality of the Syngas produced[1].
The table below shows how waste derived fuels can be classified depending on moisture content[1].
| Classification Property | Unit | Class 1 | Class 2 | Class 3 | Class 4 | Class 5 |
|---|---|---|---|---|---|---|
| Moisture Content (as received) | % wt/wt (mean) | <=10 | <=15 | <=20 | <=30 | <40 |
References
- ↑ 1.0 1.1 1.2 1.3 WRAP, 2019. A Classification Scheme to Define the Quantity of Waste Derived Fuels. Wrap.org.uk. [online] [Accessed 1 Nov. 2019]