1. Piston Press Technology
- The piston presses which are currently operating in India are also known as ram and die technology.
- Most common type of briquetting in India.
- In this case the biomass is punched into a die by a reciprocating ram with a very high pressure thereby compressing the mass to obtain a briquette.
- The pressure in the compression section is in the order of 110 to 140 Mpa
- Temperature --- Up to the Lignin is becoming fluid
- The briquette produced is 60 mm in external diameter.
- This machine has a 700 kg/hr capacity and the power requirement is 25 kW.
- The ram moves approximately 270 times per minute in this process.
2. Screw-Type Briquetting Press
- In screw type, the material is compressed in the form of a log under screw and the process is continuous without any break.
- The central hole incorporated into the briquettes produced by a screw extruder helps to achieve uniform and efficient combustion and, also, these briquettes can be carbonized
- logs are partly carbonized and free of volatile compounds
- An electrical coil heater was fixed on the outer surface of the die, to heat it to about 300ºC. This temperature is required to soften the lignin in the biomass, which acts as a binder.
- Screw Press In a screw extruder press, the biomass is extruded continuously by a screw through a heated taper die.
- The power consumption in the former is less than that of the latter.
- Briquette quality and production procedure screw press -- superior to the piston press technology.
ADVANTAGES OF BIOMASS BRIQUETTING
- The process increases the net calorific value per unit volume
- The process helps to solve the problem of residue disposal
- The fuel produced is uniform in size and quality
- The transportation cost is reduced and storage space is minimized drastically
- Absence of sulfur content in Briquettes prevents pollution to environment
- No fly ash is released during burning of briquettes
- High thermal value and much lower ash content (2-10% as compared to 20-40% in coal).
- It cannot withstand direct contact with water and covered storage facility is required.
- Maximum attainable temperature is 1000 ° C due to low carbon content.
- Burning capacity per unit volume of furnace is low compared to coal.
- The raw material is not perennial and so availability round the year is not sure.
The Status of Briquetting Technology Across the World
Briquetting technology is yet to get a strong foothold in many developing countries because of the technical constraints involved and the lack of knowledge to adapt the technology to suit local conditions. Overcoming the many operational problems associated with this technology and ensuring the quality of the raw material used are crucial factors in determining its commercial success. In addition to this commercial aspect, the importance of this technology lies in conserving wood, a commodity extensively used in developing countries and leading to the widespread destruction of forests.