# Energy Recovery via Thermal Gasification from Waste Insulation Electrical Cables (WIEC)
## 3 Results and Discussions
### Proximate Analyses  
Table 1 presents the results from proximate and ultimate analyses and high heat values. The proximate analysis demonstrates that both fuels have quite different attributes, regarding its characteristics.  
The moisture content varied between 7.43% for pine and 0.8% for WIEC, that is, both fuels are suitable for thermochemical applications. It is considered that in thermochemical processes, such as gasification and combustion, the moisture parameter should not exceed 30%. However, the thermal gasification process allows for relatively higher moisture than the combustion process, since most gasifiers use part of the thermal energy generated in the reactor, to predry the fuel before it enters the reactor.  
The high content of volatile matter that the WIEC fuel presents (68.4%), indicates that a relatively lower amount of thermal energy is necessary to initiate thermochemical reactions, that is, this fuel is considered to be suitable for the thermal gasification process at lower temperatures as compared with fuels that have a higher amount of fixed carbon. However, a higher amount of VM increases the HHV but also causes a higher probability of tar formation. This observation can be seen in Table 1.  
Regarding the biomass pine fuel, the amount of volatile matter (53.61%) is lower than WIEC fuel. As previously mentioned, fuels with moderate amounts of VM are advantageous for the thermal gasification process since the risks of tar production are reduced, avoiding bridging and problems related to bad combustion in internal combustion engines, which are often used in this type of process to generate energy.  
The fixed carbon contents of WIEC and pine are relatively close, with 30.51% and 36.36%, respectively. When the loss of volatile content is greater in the fuel, the fixed carbon residue diminishes. The high content of fixed carbon benefits the thermochemical processes since the energy density of the fuel increases with an increase in this parameter, which translates into a high energy efficiency in the gasifier. A very relevant aspect is that the fixed carbon in a gasification reactor is responsible for increasing the temperature, and is also a determinant for the thermal cracking of the tar produced during the gasification process [33].  
The ash contents of the two fuels are very similar, about 3% for pine and 2% for WIEC. The ash content for both fuels is considered to be suitable for thermochemical processes, since fuels with an ash content above 7% tend to form slag in thermochemical processes, mainly at high temperatures (around 1000 \({}^{\circ}\)C). This aspect can be problematic for the system, since it can lead to excessive formation of tar, blockages, and malfunction of the reactor. The high ash content of the fuel is also responsible for the reduction in the HHV. The thermal gasification process by means of a downdraft reactor is the most appropriate when a fuel has a high ash content, because of the constant removal of unconverted material and ashes at the bottom of the reactor, which prevents the referred problems.