**5.1. Sample production of biomass**

Dried coconut leaves were collected in a coconut farm in Calauan, Laguna (CALABARZON, Region IV-A). Cogongrass and rice husks were collected from Puerto Princesa, Palawan [5]. The dried biomass was air dried and cut into small pieces. The cut biomass was stored in plastic containers at room temperature.

#### **5.2. Characterization of the raw biomass**

#### *5.2.1. Thermogravimetric analysis (TGA)*

The thermal behaviors of dried coconut leaves [4, 5], cogongrass [5] and rice husks [5] (about 5.769 mg milled using a Thomas Willey mill) were investigated at the Polymer Materials Laboratory at the Institute of Chemistry, College of Science, University of the Philippines, Dilijan, Quezon City using a TGA Q50 (TA Instrument). The heating program consisted on a 5 min hold at 30°C, ramp up to 800°C at a heating rate of 10°C/min, and then the weight difference was recorded as a function of temperature profile. Nitrogen was used as a purging gas at a flow rate of 50 ml/min [4].

#### *5.2.2. Heating value*

The calorimetric experiments were performed using the raw and torrefied biomass. About 1 g size sample was placed in a nickel crucible introduced into a Parr 1356 Oxygen Combustion Bomb Calorimeter. The experiments were performed at 25°C. The bomb was filled with oxygen at a filling pressure of 30 atm. The calorimeter was placed in an isothermal-jacket with an air-gap separation of 10 mm between all surfaces. The calorimeter was filled with two liters of de-ionized water. The fuel was ignited through external electric connections. Temperature of this water was measured to 10−4°C at intervals of 10 s at the start of ignition to calculate the heating value for each sample [4].

#### *5.2.3. Proximate analysis*

Samples of the feedstock or raw biomass and the solid product or torrefied biomass were analyzed at the Analytical Services Laboratory at the Institute of Chemistry, U.P. Diliman, QC for moisture content using a micro thermogravimetric analyzer according to Method 925.45 B "Official Methods of Analysis of AOAC International (17th edition Revision 1)" and ash content according to Methods of Analysis of AOAC International (17th edition Revision 1)" and ash content according to method 923.03 Ibid [4].

#### **5.3. The torrefaction reactor**

The torrefaction batch reactor was developed and fabricated for the laboratory scale. The reactor which is of rotary drum type (capable of approximately 200–500 g per batch, depending on material) is made of stainless steel with an inside diameter of 20 cm, length of 30 cm and thickness of 1 cm. It consists of (1) an air locked feeder cover where the feedstock is fed; (2) the heating chamber where torrefaction process of the biomass takes place; (3) rotor blades that allows uniform heating of the biomass; (4) the thermometer that displays the temperature in the heating chamber; and (5) a tachometer that measures the rotation speed of the shaft [4]. **Figure 1** shows the schematic diagram of the torrefaction reactor and its parts. **Figure 2** shows the fabricated torrefaction batch reactor.

#### **5.4. The torrefaction experiment**

**Figure 3** shows the experimental set-up of the torrefaction experiment. Raw biomass was torrefied using the lab-scale torrefaction unit. Four torrefied samples were prepared with different feedstock conditions and different operating temperatures based on the TGA results of the untorrefied (raw) biomass (see **Table 1**).

The reactor was heated, at the rotating speed of the shaft of about 23 rpm. When the desired reaction condition was reached, the set-up was allowed to cool, the solid product or the torrefied biomass was weighed. The condensate was collected throughout the process by connecting the condensate collecting unit to a condenser. The volume and weight of the condensate were measured. The collected gas and the condensate were disposed properly. Bomb calorimetry and proximate analysis were used in determining the physical and fuel properties of the torrefied biomass. Fuel characteristics (heating value, moisture content, fixed carbon content, and ash content) of the raw and torrefied biomass were compared. Design engineering principles were used to develop a process design of the production of solid fuel from renewable biomass.

Development of Torrefaction Technology for Solid Fuel Using Renewable Biomass

http://dx.doi.org/10.5772/intechopen.76100

49

Property Coconut leaves Cogongrass Rice husk Operating temperature (°C) 245–290 247–298 238–293

**Figure 2.** The fabricated torrefaction reactor.

**Figure 3.** The experimental set-up of the torrefaction experiment.

**Table 1.** Torrefaction operating temperature conditions.

**Figure 1.** Schematic diagram of torrefaction reactor and its parts.

Development of Torrefaction Technology for Solid Fuel Using Renewable Biomass http://dx.doi.org/10.5772/intechopen.76100 49

**Figure 2.** The fabricated torrefaction reactor.

*5.2.3. Proximate analysis*

48 Gasification for Low-grade Feedstock

to method 923.03 Ibid [4].

batch reactor.

**5.3. The torrefaction reactor**

**5.4. The torrefaction experiment**

the untorrefied (raw) biomass (see **Table 1**).

**Figure 1.** Schematic diagram of torrefaction reactor and its parts.

Samples of the feedstock or raw biomass and the solid product or torrefied biomass were analyzed at the Analytical Services Laboratory at the Institute of Chemistry, U.P. Diliman, QC for moisture content using a micro thermogravimetric analyzer according to Method 925.45 B "Official Methods of Analysis of AOAC International (17th edition Revision 1)" and ash content according to Methods of Analysis of AOAC International (17th edition Revision 1)" and ash content according

The torrefaction batch reactor was developed and fabricated for the laboratory scale. The reactor which is of rotary drum type (capable of approximately 200–500 g per batch, depending on material) is made of stainless steel with an inside diameter of 20 cm, length of 30 cm and thickness of 1 cm. It consists of (1) an air locked feeder cover where the feedstock is fed; (2) the heating chamber where torrefaction process of the biomass takes place; (3) rotor blades that allows uniform heating of the biomass; (4) the thermometer that displays the temperature in the heating chamber; and (5) a tachometer that measures the rotation speed of the shaft [4]. **Figure 1** shows the schematic diagram of the torrefaction reactor and its parts. **Figure 2** shows the fabricated torrefaction

**Figure 3** shows the experimental set-up of the torrefaction experiment. Raw biomass was torrefied using the lab-scale torrefaction unit. Four torrefied samples were prepared with different feedstock conditions and different operating temperatures based on the TGA results of

**Figure 3.** The experimental set-up of the torrefaction experiment.


**Table 1.** Torrefaction operating temperature conditions.

The reactor was heated, at the rotating speed of the shaft of about 23 rpm. When the desired reaction condition was reached, the set-up was allowed to cool, the solid product or the torrefied biomass was weighed. The condensate was collected throughout the process by connecting the condensate collecting unit to a condenser. The volume and weight of the condensate were measured. The collected gas and the condensate were disposed properly. Bomb calorimetry and proximate analysis were used in determining the physical and fuel properties of the torrefied biomass. Fuel characteristics (heating value, moisture content, fixed carbon content, and ash content) of the raw and torrefied biomass were compared. Design engineering principles were used to develop a process design of the production of solid fuel from renewable biomass.
