# Microwave Pyrolysis of Biomass: The Influence of Surface Area and Structure of a Layer
## 3 Experimental Setup and Procedures  
### Experimental Setup  
A setup for the present study was designed on the basis of the review of experimental installations. The setup has the following advantages: simplicity of design and operation; flexible experimental procedure; real-time monitoring of gas concentrations; no need for additional equipment. The wavelength at a frequency of 2.45 GHz is 12.2 cm.  
One of the main components of the microwave heating setup is a magnetron. Table 2 presents the characteristics of typical magnetrons in order to understand the possibilities of choosing setup elements for specific scientific and technological tasks.  
Figure 1 presents a diagram of the experimental setup used in the present study. The main elements of the setup are a microwave oven for heating biomass and a gas analyzer (Test-1, Boner VT company, Novosibirsk, Russia) for taking a gas sample and determining the concentrations of the gas mixture components.  
\begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline \multicolumn{6}{c}{**Ultimate Analysis (\%)**} & \multicolumn{6}{c}{**Proximate Analysis**} \\ \hline
**C** & **H** & **O** & **N** & **S** & **Moisture, \%** & **Volatiles, \%** & **Fixed Carbon, \%** & **Ash, \%** & **Calorific Value, MJ/kg** \\ \hline
54.3 & 5.2 & 40.0 & 0.4 & – & 3.5 & 80.1 & 15.1 & 1.1 & 18.67 \\ \hline \hline \end{tabular}
\end{table}
Table 1: Characteristics of sawdust.  
Figure 1: (**a**). Experimental setup scheme: 1—microwave oven; 2—sampling crucible with biomass; 3—gas sampling hose; 4—gas analyzer; 5—PC; 6—turnace control unit; 7—modular probe; 8—measurement display; 9—gas inlet; 10—filter; 11—moisture collector; I—biomass sample; II—magnetron; A—distribution of a sample along the edges of the crucible; B—distribution of a sample on the entire bottom of the crucible; C—distribution of a sample on a half of the crucible bottom, (**b**). Experimental setup: 1—control unit; 2—microwave oven; 3—gas sampling hose; 4—gas analyzer.  
A ceramic crucible with a biomass sample was placed in a microwave oven. The oven was heated due to the energy produced by the magnetron. The oven control unit made it possible to adjust the heater power in the range from 200 to 800 W. In the study, we did not vary the power of the installation. The power was 800 W throughout the experiment. After the fuel was introduced into the furnace, it was hermetically sealed with a door into which a gas sampling hose was built. The gas analyzer used in the experiments is a laboratory system designed for long-term continuous measurement of the concentrations of gas mixture components formed during combustion and gasification of fuels. The device includes a standard set of elements: a modular probe, a condensate collector, a filtration system, a computing unit, a capillary and measuring electrochemical sensors (O\({}_{2}\), CO, SO\({}_{2}\), NOx, NO\({}_{2}\), H\({}_{2}\)S and HCI). Additionally, the gas analyzer was equipped with CO\({}_{2}\) and CH\({}_{4}\) optical sensors and a H\({}_{2}\) polarographic sensor. The characteristics of the measuring channels are presented in Table 3.  
The Test-1 gas analyzer was connected to a computer via an RS-232 interface. The software of the gas analyzer transmitted in real time the measured values of gas concentrations, and also archived, integrated and exported the resulting data in standard text and graphic formats. The study presents the results of direct measurement of the concentrations of individual components of the gas mixture. In the experiments, the gas mixture entering the gas analyzer was fed to several sensors at once. All sensors were only sensitive to certain components of the gas mixture. The analytical measurement range for each sensor was set by the manufacturer. During the experiments, the concentrations of individual gases did not exceed the measurement range of the sensors. Since the sensors were calibrated and metrologically verified, no further confirmation of the analytical range was required.