National Conference on Advances in Mechanical Engineering Science (NCAMES-2016)

ISSN: 2231-5381 http://www.ijettjournal.org Page 69

Analysis of Various Characteristics of

Coconut Leaves as a Biomass Briquette Deepak K.B

1, Dr. N.A.Jnanesh

2

1Research Scholar, Mechanical Department, Vivekananda College of Engineering & Technology, Puttur

2Principal, Mechanical Department, K.V.G.College of Engineering, Sullia-574327,

Abstract— Coconut leaves are usually used for

making brooms; temporary roofing’s or dumped and

flared in farms resulting in environmental pollution.

Densification of these loose biomass coconut leaves

results in improved density, storage, transportation

and handling. This work investigated the various

characteristics of coconut leaves as a biomass

briquette. Coconut leaves were collected, dried,

milled, sieved and a size of 850µ was selected for the

purpose of making briquettes. These residues were

mixed with sawdust and wheat flour which acted as

additive and binder respectively in 2:1:1 ratio. The

IS 1448-7 and IS 1350 were used to determine the

gross calorific value, proximate and ultimate

analysis respectively, while the ASAE standards

were used to determine the density, relaxation and

compact ratio. From the analysis the calorific value

was found to be 3672.41 Kcal/Kg, similarly the

density, relaxation and compact ratio were 0.502,

1.98 and 2.52 respectively. The study concluded that

production of briquettes from coconut leaf briquettes

are cheaper and feasible, as they are abundantly

available and also briquetting them results in

environmental friendly products. The various

characteristics of these briquettes were good enough

to make good biomass energy

Keywords — Coconut leaf, briquette, density,

proximate and ultimate analysis, gross calorific

value.

.

I. INTRODUCTION

The importance of energy in nation development

cannot be overemphasized as this can contribute

immensely to economic and social life of such

nation [1]. Fossil fuels are the most important energy

sources and its consumption is increasing day by day,

due to escalating population and industrial growth in

developing and developed countries [2]. As a result

of the growing worldwide concern regarding

environmental impacts - particularly climate change

from the use of fossil fuels, the volatile fossil fuel

market and the need for an independent energy

supply to sustain economic development, there is

currently a great deal of interest in renewable energy

in general and biomass energy in particular [3-5].

Today, biomass is seen as the most promising

energy source to mitigate greenhouse gas emission.

Large scale introduction of biomass energy could

contribute to sustainable development on several

fronts namely; environmental, social, and

economical [6].

Many non-woody biomass residues suffer from

major disadvantage of having low bulk densities for

their efficient utilization. For example, the bulk

density of the majority of agro-residues lies in the

low range of 50–200 kg/m3 (Table 13.1) as

compared to 800 kg/m3 for coal of the same size.

This results in huge storage space requirements,

difficulty in handling, and higher transportation

costs, which makes them uneconomical as a

marketable commodity. Also, low bulk densities and

the loose nature of available biomass are associated

with faster burning of fuels resulting in higher flue

gas losses (lower operating thermal efficiencies) and

emissions in the form of fly ash or particulates in the

atmosphere. This makes them poor quality biomass

fuels. In order to improve the marketability of the

available loose biomass as fuel, pre-processing

becomes necessary.

Densification of biomass can be done by the

briquetting or pelletizing technology that compresses

loose biomass into densified forms. This reduces the

transportation and storage costs, and improves the

effectiveness of biomass for use as a combustible

fuel [7].

India produces nearly 350 million tonnes of

agricultural waste per year. It has been estimated

that 110-150 million tonnes crop residues is surplus

to its present utilization as a cattle feed,

constructional and industrial raw material and as

industrial fuel [8].

Coconut leaf residues are abundantly available

in Karnataka, as these are one of the cash crops

grown. It is estimated that about 12 million people in

India are dependent on the coconut sector in areas of

cultivation, processing and trading activities. With

an annual production of around 21,892 million nuts,

coconut contribution to nation’s GDP is about

15,000 crores rupees. The Coconut (Cocos nucifera)

is a benevolent tree, a nature’s gift to mankind. The

coconut tree provides clothing, utensils and shelter

therefore, is an important source of earning

livelihood to the people of coconut growing states.

The coconut crop is grown in 12.2 Million hectares

of land which constituted about 0.7% of net crop

area of the world. India contributes about 15.46% in

area and 26.34% in terms of production of coconut

in the world. The major coconut crop acreage is

concentrated in the states of Kerala, Karnataka,

National Conference on Advances in Mechanical Engineering Science (NCAMES-2016)

ISSN: 2231-5381 http://www.ijettjournal.org Page 70

Tamil Nadu and Andhra Pradesh. Karnataka stands

second in area (507 thousand hectare) and

production (5893 million nuts) [9].

As a result of growing concern for a cleaner

energy, many renowned researchers have worked on

various aspects of briquettes [10]-[14]. This study

therefore assessed some of the associated

characteristics of coconut leaf briquettes.

II. MATERIALS AND METHODS

Coconut leaves as shown in fig.1 were collected

from a nearby farm, cut into small pieces, sundried

for a couple of days to drive out most of the

moisture, later milled, sieved, and a size of 850µ as

shown in fig.2, were selected for the purpose of

briquetting. Sizing was done as per ASTM E11 [15].

Fig.1: Coconut leaf

Fig.2: Coconut leaf of size 850µ

Biomass briquettes were prepared by mixing

coconut leaves of size 850µ, sawdust as additive and

wheat flour as a binder in 2:1:1 ratio i.e. 100gm of

coconut leaves, 50gms of sawdust powder and

50gms of wheat flour along with the required

quantity of water. This mixture was mixed and kept

in a container for a couple of days so as to get a

softened mixture.

For the purpose of making briquettes a single

mould piston and ram type briquetting machine was

fabricated as shown in fig.3. A pressure of 1.28MPa

was applied on the biomass blend placed in the

mould by using a hydraulic jack. The pressure was

maintained for a period of 5 minutes [16], and later

ejected from the mould.

Fig. 3: Briquetting Machine

The wet briquettes after being taken out of the

mould cavity were sun dried for a period of 19 days

[17]. Later, the wet and dry briquettes were weighted

and tabulated as shown in Table I, below:

Table 1: Wet and dry weight of the coconut leaf

briquettes

Sl.No Type of

briquette

Wet

weight

(kg)

Dry

weight

(kg)

Binder used : Sawdust

1 Coconut

leaves 850 µ 362.37 210.54

To determine the percentage of moisture

content, volatile matter, ash and fixed carbon of

briquettes made from coconut leaves of 850 µ,

proximate analysis was done as per IS 1350 [18] and

ultimate analysis was done as per IS 1350 [18] to

determine the percentage of oxygen, nitrogen,

sulphur and hydrogen. The gross calorific value was

done as per IS 1448-7 [19].

The initial density of coconut leaf, sawdust and

wheat flour was calculated using ASAE standards

[20].

Coconut leaf: Initial volume (Vi) = 3333.33 ml

Final volume (Vf) = 3416 ml

Mass = 100 gm

Density, ρ = Mass/ (Vf - Vi)

= 100/ (3416 – 3333.33) = 1.09 gm/cm3

Therefore volume of Coconut leaf = Mass/Volume

= 100/1.09 = 91.74 gm/cm3

Sawdust:

Initial volume (Vi) = 3333.33 ml

Final volume (Vf) = 3445 ml

Mass = 50 gm

Density, ρ = Mass/ (Vf - Vi)

= 50 / (3445 – 3333.33) = 0.44 gm/cm3

Therefore volume of Sawdust = Mass/Volume

= 50/0.44= 113.63 gm/cm3

National Conference on Advances in Mechanical Engineering Science (NCAMES-2016)

ISSN: 2231-5381 http://www.ijettjournal.org Page 71

Wheat flour:

Initial volume (Vi) = 3333.33 ml

Final volume (Vf) = 3422 ml

Mass = 50 gm

Density, ρ = Mass/ (Vf - Vi)

= 50 / (3418 – 3333.33)= 0.590 gm/cm3

Therefore volume of Wheat flour = Mass/Volume

= 50 / 0.590= 84.74 gm/cm3

The initial, maximum and relaxed densities

were also determined using ASAE standard methods

[21]. The maximum density was determined

immediately after the briquette was ejected from the

mould. The weight was determined by using digital

weighting scale and the dimensions measured using

Vernier digital caliper.

Wet weight of the briquette (immediately after

ejection from the mould) = 362.37 gm

Wet volume of the briquette = l x b x h = 12.21 x

8.19 x 4.17 = 416.99 cm3

Cylindrical wet volume of hole φ 8 mm, present

throughout the briquette = ∏ x 42 x 4.17

= 209.60 cm3

Therefore, total wet volume of the briquette =

416.99 – 209.60

=

207.39 cm3

Maximum density of the briquette immediately after

ejection from the mould =

Mass of wet briquette / Volume of wet

briquette =362.37/207.39= 1.74 gm/cm3

The relaxed density of the briquette was

determined in the dry condition after nineteen days.

The relaxed density is calculated after the briquette

has become stable and it is defined as the ratio of

briquettes mass in dry state to its new volume.

Dry weight of the briquette (after 19 days) = 210.54

gm

Dry volume of the briquette = l x b x h = 12.28 x

8.34 x 4.61 = 472.13 cm3

Cylindrical dry volume of hole φ 8 mm, present

throughout the briquette = ∏ x 42 x 4.61 =

231.72cm3

Therefore, total dry volume of the briquette = 472.13

– 231.72= 240.41 cm3

Relaxed density of the briquette in dry condition =

Mass of dry briquette / Volume of dry

briquette = 210.54/240.41 = 0.875 gm/cm3

Initial density of the biomass, i.e. density of

coconut leaf, sawdust and wheat flour before

compression,

Initial density = Mass/Volume

= 200/ (coconut leaf + sawdust volume +wheat

flour)= 200/ (91.74+113.63+84.74) = 0.689 gm/cm3

Density ratio is calculated as the ratio of relaxed

density to maximum density. Maximum density is

the compressed density of briquette immediately

after ejection from briquetting machine.

Density Ratio = Relaxed density / Maximum

density= 0.875/1.74= 0.502

Relaxation ratio is calculated as the ratio of

maximum density to relaxed density.

Relaxed Ratio = Maximum density / Relaxed density

= 1.74/0.875

= 1.98

Compaction ratio which is defined as, the

maximum density divided by the initial density of

the residue.

Compaction Ratio = Maximum density / Initial

density before compression

= 1.74/0.689

= 2.52

III. RESULTS AND DISCUSSIONS

The results obtained from proximate and

ultimate analysis and the physical and combustion

characteristics of the biomass coconut leaf

briquettes are as shown below:

Table 2: Physical and fuel characteristics

Parameter Unit Volume

Length of the

briquette cm 12.28

Breadth of the

briquette cm 8.34

Thickness of the

briquette cm 4.61

Weight of the

briquette Kg 0.210

Hydrogen content % 6.82

Nitrogen content % 0.59

Sulphur content % 0.58

Oxygen content % 19.15

Ash content % 3.33

Volatile content % 85.05

Moisture content % 6.90

Fixed Carbon

content % 4.72

Table 3: Combustion characteristics of Coconut

leave briquettes

Parameter Unit Volume

The heating value Kcal/Kg 3672.41

Initial density Kg/Cm3 0.689

Maximum density Kg/Cm3 1.74

Relaxed density Kg/Cm3 0.875

Density ratio 0.502

Compaction ratio 2.52

Relaxation ratio 1.98

National Conference on Advances in Mechanical Engineering Science (NCAMES-2016)

ISSN: 2231-5381 http://www.ijettjournal.org Page 72

Calorific value is very important for a briquette,

as it determines the energy content of a fuel. The

calorific value of coconut leaf briquette of grain size

850µ is 3672.41Kcal/kg, and this is sufficient to

produce the required heat necessary for domestic

and industrial application.

Proximate analysis indicates the percentage of

moisture, ash, volatile matter and fixed carbon

content were determined using proximate analysis.

The main parameters that determine briquette quality

is the moisture content [22]. Lower the moisture

content, higher is the calorific value. From Table 1,

the moisture content of coconut leaves briquette is

6.90%, and this value is good , as lower the moisture

content higher is the calorific value and also it

assists the storability and combustibility of the

briquettes [25].

Higher the volatile content, easier is the ignition

of the briquettes. From Table 2 coconut leaves

briquette has a volatile content of 80.05% is a good

indication of easy ignition of the briquette and

proportionate increase in flame length [26].

The percentage of ash in coconut leaves

briquette was found to be 3.33%, which is good,

because ash doesn’t burn, and it’s better to have

percentage of ash content as less as possible. Higher

the amount of ash content, results in more dust, less

efficiency and combustion rate. The calorific value

goes on reducing as the percentage of ash increases

[26].

The percentage of fixed carbon for biomass

coconut leaves briquette was 4.72% and this value is

favorable, as it aids in slow burning of fuel, resulting

in prolong heat release [27].

The various chemical constituents such as,

hydrogen, oxygen, sulphur and nitrogen were found

by ultimate analysis. The composition of the coconut

leaves briquette analysed showed, 19.15% oxygen,

0.59% nitrogen and 0.58% sulphur. The results agree

with the observations made [28]. The amount of

hydrogen content in the biomass briquette examined

is very satisfactory as they contribute immensely to

the combustibility of any substance in which they

are found [29]. The low sulfur and nitrogen contents

which are below 1% are encouraging as it results in

less environmental pollution [30].

The values of relaxed density, maximum density

and relaxation ratio obtained for areca leave

briquettes were 0.875Kg/m3, 1.74Kg/m

3 and 1.98

respectively. The value of maximum and relaxed

density obtained in this work agrees well with the

value obtained from other biomass briquette research

works [26] - [31].

IV. CONCLUSIONS

The results of this study have shown that, the

briquettes produced from coconut leaves with

sawdust as a binder and wheat flour as additive

would make good biomass fuels. The following

observations were made during the investigation:

aids in faster combustion, as percentage of

volatile matter is more ,

calorific value high enough to produce

sufficient heat,

favorable compaction process, as

percentage of moisture content is less,

resulting in less environmental pollution,

percentage of nitrogen and sulphur content

less,

The relaxed densities of the coconut leaves

briquettes are more than the initial densities

of the residues, resulting in easier storage,

handling and transportation.

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