7 Experiment on Briquetting Technology.ppt

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1. ERG 211 RENEWABLE ENERGY AND GREEN
TECHNOLOGY (1+1)
Practical -7
Experiment on Briquetting Technology
Aim: To study the briquettes production process and
determination of physical properties of briquettes

2. Experiment on Briquetting Technology
Principle
Densification techniques
Densification essentially involves two processes, the
compaction under pressure of loose material to reduce its
volume and to agglomerate the material so that the
product remains in the compressed state.
On the basis of compaction, the briquetting technologies
can be divided into
High pressure compaction
Medium pressure compaction with a heating device
Low pressure compaction with a binder
Two main high pressure technologies: ram or piston press
and screw extrusion machines, are used for briquetting.

3. Experiment on Briquetting Technology
i) Piston press densification
A reciprocating piston pushes the material into a tapered
die where it is compacted and adheres against the
material remaining in the die from the previous stroke.
A controlled expansion and cooling of the continuous
briquette is allowed in a section following the actual die.
The briquette leaving this section is still relatively warm
and fragile and needs a further length of cooling track
before it can be broken into pieces of the desired length.
The most common type of briquette press features a
cylindrical piston and diewith a diameter ranging from 20-
125 mm.

4. Experiment on Briquetting Technology
i)Piston press densification
The die tapers somewhat towards the middle and then
increases again before the end.
The exact form of the taper varies between machines
and biomass feedstock and is a key factor in determining
the functioning of the process and the resulting
briquette quality.

5. Experiment on Briquetting Technology
ii) Screw Press densification
In the screw press technology, the biomass is extruded
continuously by a screw through a taper die which is
heated externally to reduce the friction.
Material is fed continuously into a screw which forces the
material into a cylindrical die, which is often heated to
250-300 °C to raise the temperature to the point where
lignin starts flowing.
Briquettes produced from screw press are often of high
quality than piston-press unit but the power requirement
per tonne of briquette produced is also high.

6. Experiment on Briquetting Technology
ii) Screw Press densification

7. Experiment on Briquetting Technology
Compare Piston press and Screw Press densification
Parameters Piston press Screw Press
Optimum moisture content of raw
material (%)
10-15 8-9
Wear of contact parts low in case of ram and
die
high in case of
screw
Output from the machine In strokes Continuous
Power consumption (kWh/ton) 50 60
Density of briquette (gm/cm³) 1 -1.2 1 -1.4
Maintenance High Low
Combustion performance of
briquettes
not so good very good
Carbonization to charcoal not possible makes good
charcoal
Suitability in gasifiers not suitable Suitable
Homogeneity of briquettes non-homogeneous Homogeneous

8. Experiment on Briquetting Technology
Measurement of strength and durability
The effectiveness of the briquettes created during the
densification process has been measured in terms of
strength and durability.
Apparatus required:
Briquette,
Water and
Beaker

9. Experiment on Briquetting Technology
Measurement of strength and durability
a. Water resistance
Short-term exposure to rain or high humidity conditions
during transportation and storage could adversely affect
the quality of the densifiedproducts.
To assess its stability against these adverse conditions, water
resistance can be tested using the following procedure.
Water resistance is the percentage of water absorbed by a
briquette, when immersed in water.
i) Each briquette was immersed in water at 27 C for 1 min.
ii) Note the difference in weight.

10. Experiment on Briquetting Technology
Measurement of strength and durability
a.Water resistance
Calculation:
Initial weight of the briquette = W
1, kg
Final Weight of the briquette = W
2, kg
Difference in weight of the briquette, kg = W
2–W
1

11. Experiment on Briquetting Technology
Measurement of strength and durability
b. Impact resistance
Impact resistance (or drop resistance or shattering
resistance) test may simulate the forces encountered
during emptying of densified products from trucks onto
ground, or from chutes into bins.
The drop resistance test to determine the durability of
biomass pellets and briquettes.

12. Experiment on Briquetting Technology
Measurement of strength and durability
b. Impact resistance
i)Drop the pellets from 1.85 m height onto a metal plate
4 times.
ii)Take the weight retained in the briquette as % of the
initial weight is taken as the pellet/briquette durability.
Calculation
Initial weight of the briquette = W
1, kg
Final Weight of the briquette = W
2, kg
Briquette durability, % = W
2/ W
1

13. Experiment on Briquetting Technology
Measurement of strength and durability
c. Water stability test
Water stability of a briquette is defined as the retention of
the briquette’s physical integrity with minimal
disintegration while it is immersed in the water.
i. Dip the briquettes in water
ii. If it broken into pieces in less than
< 5 min Very low-quality briquette
< 15 min Medium quality briquette
< 20 min Good quality briquette