Performance Studies on a Downdraft Biomass Gasifier with Blends of Coconut Shell and Rubber Seed Shell as Feedstock

Accepted Manuscript
Title: Performance studies on a downdraft biomass gasifier with blends of
coconut shell and rubber seed shell as feedstock
Author: V. Christus Jeya Singh, S. Joseph Sekhar
PII:
DOI:
Reference:

S1359-4311(15)01026-1
10.1016/j.applthermaleng.2015.09.099
ATE 7096

To appear in:

Applied Thermal Engineering

Received date:
Accepted date:

24-4-2015
25-9-2015

Please cite this article as: V. Christus Jeya Singh, S. Joseph Sekhar, Performance studies on a
downdraft biomass gasifier with blends of coconut shell and rubber seed shell as feedstock,
Applied Thermal Engineering (2015), />10.1016/j.applthermaleng.2015.09.099.
This is a PDF file of an unedited manuscript that has been accepted for publication. As a service
to our customers we are providing this early version of the manuscript. The manuscript will
undergo copyediting, typesetting, and review of the resulting proof before it is published in its
final form. Please note that during the production process errors may be discovered which could
affect the content, and all legal disclaimers that apply to the journal pertain.

Performance Studies on a Downdraft Biomass Gasifier with
Blends of Coconut Shell and Rubber Seed Shell as Feedstock
V. Christus Jeya Singh1* and S. Joseph Sekhar1
1

Department of Mechanical Engineering, St. Xavier’s Catholic College of Engineering,
Nagercoil, Kanyakumari, Tamilnadu, India.
Corresponding author: *

Keyword: Coconut shell, Rubber seed shell, Downdraft gasifier, Equivalence ratio,
Conversion efficiency

Highlights:



Analytical and experimental investigation on the performance of biomass gasifier



Blends of coconut shell and rubber seed shell as feedstock in gasifier instead of wood



Two-zone kinetic model to predict the performance of biomass blends in gasifier



Impact of equivalent ratio on the performance of gasifier with blends of biomasses

Abstract
The use of biomass gasification system for the generation of combined heat and
power has gained importance, because it is considered to be one of the most promising
renewable energy technologies. Widespread research has been already carried out on
downdraft gasifier with single biomass as feedstock. However a limited work is available to
ascertain the feasibility of utilizing blends of biomasses. In this paper, theoretical and
experimental studies have been carried out on a 50kWth downdraft gasifier with the blends of
coconut shell and rubber seed shell, which are available abundantly in the rural villages of
South India. Two-Zone kinetic modelling is followed for the theoretical studies. Experimental
0 | Paper ID :ICP2015-CP141
Page 1 of 13


study has been carried out to prove the validity of the modelling approach. The results show
that the mixing of rubber seed shell and coconut shell with various compositions yields the
performance which is on par with the woody biomasses. Besides, the maximum values of the
performance parameters are obtained when the equivalence ratio is maintained between 0.2
and 0.3.
Introduction
The fossil fuels contribute 80% to world total energy demand, whereas biomass
resources cover only 10-15% [1]. India has an immense opportunity for energy generation
from the available 500 metric tons of biomass per year. The rural areas of India depend on
conventional biomasses such as firewood, animal dung, agricultural residue and forest
products. for cooking, heating, lighting and other related applications. It is also observed that
the biomass energy technology may contribute to one-third of total energy consumption in
India [2&3].
Biomass gasification process comprises of biochemical reactions inside the gasifier
with limited supply of air, and generates combustible gases such as CO, H2 and CH4. The
energy content of the combustible gases may be conveniently used for heat and power

applications. These gases can be effectively utilised in advanced technologies like gas
turbines and fuel cells in order to get increased system efficiency [4]. The concept of
combined heat and power production from biomass is especially useful to agriculture based
process industries and rural electrification in developing countries [5&6].
The performance of the gasification process depends on the types of feedstock and its
characteristics such as moisture content, composition (ultimate analysis), equivalence ratio
and so on. Inappropriate selection of these parameters may lead to excessive presence of tar
and soot in the producer gas. These unwanted materials in the producer gas may disturb the
continuous and smooth operation of gas engines [7&8]. The fixed bed gasifiers are classified
depending on the supply of gasifying agent into the reactor. They are updraft, downdraft,
cross draft and multistage. Among the commercially produced gasifiers, downdraft, fluidized
bed, updraft and other gasifiers have the share of 75%, 20%, 2.5 % and 2.5% respectively [9].
Compared to other gasification technologies, the downdraft gasifier is the most sustainable
option for decentralized heat and power generation because the producer gas obtained from it
contains very low content of tar and particulates.

1 | Paper ID :ICP2015-CP141
Page 2 of 13


Theoretical and experimental studies have been carried out to analyse the behaviour
of gasifiers. The minimization of Gibbs free energy has been followed [10] to predict the
performance of wood waste (saw dust). This approach was found to be good to analyse the
gasification process above 1500 K [11]. Another model developed based on thermodynamic
equilibrium approach by Jarungthammachote and Dutta [12] has considered the equilibrium
constant with correction coefficient for predicting the composition of producer gas in a
downdraft gasifier. It is also suggested that the moisture content and equivalence ratio have to
be maintained at 10 to 20% and 0.3 to 0.45 respectively for optimal energy conversion.
Chemical equilibrium approach has been used to analyse the influence of parameters such as
moisture content, equivalence ratio and heating value on the quality of producer gas [11&12].

The experimental works have been carried out to predict the influence of various
factors on the performance of downdraft biomass gasifier with wood [13, 18], waste wood,
wheat straw, coconut shell [14, 18], saw dust [15], cashew nut shell [16], agricultural and
forest residues [17], rubber seed kernel, coir-pith [18], etc. as feedstock. A numerical and
experimental study conducted to analyse the behaviour of reduction zone shows that the
conversion efficiency of the gasifier decreases as the throat angle increases. The optimum
length of the reduction zone has been reported as 22 cm for efficient operation of the gasifier
[13].
The gasifier running with single biomass throughout the year suffers with issues such
as risk on transportation, non-availability of a particular biomass throughout the year and
incomplete utilization of various biomasses available in a region [19]. Therefore blends of
biomasses in a gasifier can improve the continuous and steady operation of gasifiers in
remote areas. A analytical model developed to analyse the performance of saw-dust/cowdung mixture in a downdraft gasifier shows that the mixing of cow dung would reduce the
gas production rate and heating value, however, having 40 - 50 % cow dung in the mixture is
technologically and economically viable [20]. To the further extent of this approach, through
this paper, the performance of a 50 kWth downdraft gasifier has been analysed with the
blends of coconut shell-rubber seed shell. Equilibrium modelling concept has been used in
the theoretical studies. Experiments were also conducted to investigate the effect of mixture
composition and equivalence ratio on the species concentration and heating value of the
producer gas.
Methodology
2 | Paper ID :ICP2015-CP141
Page 3 of 13


The total gasifier model has been simplified into two different zones as shown in
Fig.1. The thermodynamic equilibrium approach is followed in the zone-1 while chemical
kinetics of reactions has been considered in zone-2 [20]. In order to implement the
equilibrium analysis, the assumptions used in this analysis are steady state gas flow inside the
gasifier, adiabatic wall, infinite residence for the reactions to take place, uniform species

temperature at each level of gasification, negligible amount of tar or unburnt hydrocarbon in
the exhaust, ideal gas behaviours of gases. And major species in the product gas are CO, CO2,
H2, CH4 and N2.
The blends of two biomasses in various proportions have been used as feedstock in
the gasifier instead of single biomass, and the performance parameters like heating value,
species concentration, gas production rate and conversion efficiency were studied. While
using two different biomass energy sources, the global reaction of gasification process for the
mixture can be written as [20],
𝐶𝐻𝑙 𝑂𝑝 𝑁𝑞 + 𝑏𝐶𝐻𝑡 𝑂𝑢 𝑁𝑣 + 𝑀𝑤 𝐻2 𝑂 + 𝑋𝑔 𝑂2 + 3.76𝑁2
→ 𝑥1 𝐶𝑂 + 𝑥2 𝐻2 + 𝑥3 𝐶𝑂2 + 𝑥4 𝐻2 𝑂 + 𝑥5 𝐶𝐻4 + 𝑥6 𝑁2 + 𝑥7 𝐶

(1)
(1)

Where l, p, q, t, u, and v are the number of atoms of the respective chemical
component in the feedstock. The representative chemical formulae (CHlOpNq, CHtOuNv) of
different biomasses are derived from their ultimate analysis, using the generalized procedure
[21]. The equations used for calculating the number of moles of second biomass (b), number
of moles of oxygen in air (Xg) and the number of moles of moisture (Mw) have been taken
from published literature [20]. The ultimate analysis results of feedstock materials are shown
in the Table 1.
The higher heating value of the biomass is calculated using the Friedl’s equation.
𝐻𝐻𝑉 𝑀𝐽 𝑘𝑔 = 3.55𝐶 2 − 232𝐶 − 2230𝐻 + 51.2𝐶𝐻 + 131𝑁 + 20600

(2)

The numbers of moles of respective species, x1 to x7 in the gasification process have
been calculated by solving the global reaction [20]. A uniform temperature has been assumed
to the species at the outlet of zone-1 and the same is determined from the energy balance

3 | Paper ID :ICP2015-CP141
Page 4 of 13


across the zone considering that there is a negligible amount of kinetic and potential energy
changes.
Based on the global reaction given in equation 1, the energy balance equation is
expanded as [20],
𝐻𝑓1 + 𝑏𝐻𝑓2 + 𝑋𝑔

𝑇𝑎
𝑇0
6

𝐶𝑝 𝑂 2 𝑑𝑇 + 3.76𝑋𝑔

=

𝑇𝑎
𝑇0

𝐶𝑝 𝑁 2 𝑑𝑇 + 𝑀𝑤 ℎ𝑓 𝐻2𝑂 + 𝑄𝑙𝑜𝑠𝑠

𝑇

𝑥𝑖 ℎ𝑓𝑖 +
𝑖=1

𝑇0

(3)

𝐶𝑝 𝑖 𝑑𝑇 + 𝑥7 𝐶𝑝𝐶 𝑇 − 𝑇0 + 𝑚𝑎𝑠ℎ 𝐶𝑝𝑎𝑠 ℎ 𝑇 − 𝑇0

The energy carried out by individual species (CO, H2, CO2, H2O, CH4, and N2), char
and ash are considered separately in the above equation. Standard equations are used to find
the heat of formation of fuels [22]. Specific heat for ash and char is considered as 840 J/kgK
and 21.86 J/mol K respectively [20].
The species formed in the zone-1 enter the zone-2 and undergo the following
endothermic reactions to form the final composition of the producer gas [20].
𝐶 + 𝐶𝑂2 ⇔ 2𝐶𝑂

(4)

𝐶 + 𝐻2 𝑂 ⇔ 𝐶𝑂 + 𝐻2

(5)

𝐶 + 2𝐻2 ⇔ 𝐶𝐻4

(6)

𝐶𝐻4 + 𝐻2 𝑂 ⇔ 𝐶𝑂 + 3𝐻2

(7)

The above equations are assumed to be reversible and the rate of reaction is calculated
using Arrhenius type kinetic rate equations. The mass flow rate of the species (i=1 to 7) at the
inlet of the reduction zone depends on the feed rate of biomass. The rate of formation of
species and the temperature of the species formed in the zone-2 are calculated from the

relations used in the previous literature [20]. The temperature of the species leaving zone-2 is
obtained by applying energy balance across zone-2. The linear and non-linear equations are
solved using appropriate tools in the open source software SCILAB.
The equivalence ratio plays a vital role on the performance of the gasifier [23]. If the
equivalence ratio is below 0.2, the conversion efficiency and gas production rate reduce

4 | Paper ID :ICP2015-CP141
Page 5 of 13


drastically [24]. Therefore in this analysis, the equivalence ratio has been taken between 0.2
and 0.45, and the variations in performance parameters are studied. The blends used in this
study and their compositions are given in Table 2.
Experimental Setup
The schematic diagram of the experimental setup consists of an imbert downdraft
biomass gasifier (50 kWth), scrubber with cyclone separator and filters is shown in Fig. 2.
The feedstock to be used in this gasifier as per supplier specification is wood chip. A gas
analyser, gas chromatograph and a gas flow meter are provided to measure the quality and
quantity of the producer gas. Calibrated K-type (chromel-alumel) thermocouples are placed
in different locations along the axis of the gasifier to measure the temperature at various
zones. To prevent the leakage of producer gas and to reduce its temperature, a water seal
arrangement is made under the reactor. A special metering rod is also provided to calculate
the flow rate of feedstock. To maintain a homogeneous mixture, the biomasses were mixed
before being filled in the gasifier. Using the special arrangement, the flow rate of feedstock
was also recorded. A data logger was used to record the temperature in an interval of 5
minutes. Samples of the gas were taken every 10 minutes to analyse its composition. In
addition to that, the quantity of the output gas was also recorded. Each blend was studied for
a minimum of three times and the average values were taken. The equivalence ratio was
regulated by controlling the air flow rate and it was measured with an accuracy of ± 1 %.
HHV and moisture content of feedstock material were checked before each loading.

Results and Discussion
The theoretical work is carried out to study the variation in performance parameters
for a wide range of equivalence ratios between 0.2 and 0.45. However, the experimental
studies were carried out by maintaining the equivalence ratio between 0.2 and 0.34. The
comparison of species concentration obtained from the present model with the previous
works [12] shows that the deviation of present result is within 12%. Thus the validity of the
2-zone kinetic equilibrium approach to simulate the gasifier has been proved. The results
obtained from modelling and experimental studies have been analysed, and the influence of
the equivalence ratio and composition of biomass blends on the performance parameters are
evaluated.
5 | Paper ID :ICP2015-CP141
Page 6 of 13


a) Species concentration
The variations in species concentration (CO, H2, CO2, CH4 and N2) with equivalence
ratio for coconut shell and rubber seed shell are shown in Fig. 3 and Fig. 4 respectively. The
results show that the species concentration of CO, H2 and CH4 from the modelling has a close
agreement with that of experimental observations. It is also observed that the combustible gas
composition for both biomasses is high when the equivalence ratio is close to 0.2. However the
species concentration of the combustible gases produced using coconut shell is higher than the
other one. This might be because of the higher carbon content in coconut shell.
The reduction zone plays a vital role in the performance of the gasifier. The endothermic
reactions [24] that take place in the reduction zone cause the reduction in the temperature and
release CO, H2 and CH4. Since the concentration of CH4 does not vary significantly, the
variations of CO and H2 are plotted in Fig. 5 and Fig. 6 respectively and considered for the
discussion. A steady increase in CO concentration is observed along the reduction zone whereas
the concentration of H2 is almost constant. This is due to the difference in the rate of reaction of
each reaction. The concentration observed for CO and H2 is almost constant when the reduction
zone distance is beyond 0.24 m. A similar trend has also been observed in previous works [25].

The quality of the producer gas leaving the gasifier depends on the concentration of
the combustible gases (CO, H2 and CH4) at the exit of the gasifier. Even though the
theoretical analysis was carried out for all the blends given in Table 2, only the results of the
blend D1 is plotted in Fig. 7 and considered for discussion. It is observed that the species
concentration of combustible gases is high when ф is kept at 0.2. Therefore, the airflow rate
should be adjusted to maintain the equivalence ratio close to 0.2 for both of the feedstock
materials.The trend observed from the experimental study is similar to the prediction from the
simulation.
b) Gas production rate
The Fig. 8 demonstrates the variation of gas production rate with equivalence ratio for all
compositions used in the study. It is observed that there is a good agreement between the
predicted and measured values. Even though the combustible gas composition decreases due
to the increase in ф, an increase in gas production rate is observed. This is caused by the high
concentration of non-combustible gases such as CO2 and N2 in producer gas. When the

6 | Paper ID :ICP2015-CP141
Page 7 of 13


equivalence ratio increases, the quantity of O2 increases, and due to the domination of
combustion reactions, the production of CO2 increases. This causes a reduction in the
concentration of CO and H2.
c) Higher Heating Value and Conversion Efficiency
The heating value depends on the concentration of CO, H2 and CH4 in the producer
gas. The variation of HHV of producer gas with equivalence ratio (ф), for various feedstock
compositions is plotted in Fig. 9. It is observed that the HHV reduces with the increase in
equivalence ratio (Fig. 9). Since the gas production rate is almost constant until the
equivalence ratio reaches 0.3(Fig. 8), to maintain a high heating value of the producer gas,
equivalence ratio may be kept between 0.2 and 0.3. Next to the pure biomass (blend D0), the
blend D1 gives better performance at this range.

The impact of equivalence ratio on conversion efficiency is depicted in Fig. 10. The
conversion efficiency decreases with the increase in equivalence ratio. This is due to the poor
quality of producer gas as discussed in the previous section (Fig. 9). It is observed that the
conversion efficiency is maximum when the biomass blend is rich in coconut shell. When
rubber seed shell is mixed with coconut shell, the conversion efficiency is reasonably good
for the equivalence ratio between 0.2 and 0.3. This prediction shows that the equivalence
ratio should be kept in the above said range for the feedstock combinations used in this study.
Moreover the temperature obtained from the simulation and experimental studies at
the reduction zone is matching with the values reported in the literature (26). For instance the
temperature at the reduction zone entry for blend D1 is 1285K and 1267K for simulation and
experimental observations respectively. This proves the validity of energy equations used in
this study.

Conclusion
Theoretical and experimental studies were conducted with various binary blends of
coconut shell and rubber seed shell as feedstock in a 50kWth downdraft gasifier. Based on the
present study the following conclusions are made.

7 | Paper ID :ICP2015-CP141
Page 8 of 13


1. The concentration of combustible gases in the producer gas is maximum at equivalence
ratio close to 0.2 and a significant reduction in the concentration of CO and H2 is observed
when the equivalence ratio is beyond 0.3.
2. Irrespective of the compositions in the blend, to obtain maximum conversion efficiency,
the equivalence ratio should be maintained between 0.2 and 0.3.
3. Among the two energy sources, coconut shell shows maximum combustible species
concentration and conversion efficiency.
4. The present study proves that the coconut shell and rubber seed shell can be used as a

single biomass or blends in a biomass gasifier, which is designed for wood.
Nomenclature
ɸ

- Equivalence Ratio

DAF

- Dry Air Free

HHV

- Higher Heating Value (MJ/kg)

D0, D1, D2, D3 - Blends of Coconut Shell and Rubber Seed Shell
- Moisture Content of Biomass

MC
References

[1] A. Faaij, Modern biomass conversion technologies, Mitigation and Adaptation
Strategies for Global Change 11(2006) 343-375.
[2] C.C. Sreejith, C. Muraleedharan, P. Arun, Performance prediction of steam
gasification of wood using an ASPEN PLUS thermodynamic equilibrium model,
International Journal of Sustainable Energy 33(2013) 416-434.
[3] A. Kumar, D. Jones, M.A. Hanna, Thermochemical biomass gasification: A Review
of the Current Status of the Technology, Energy 2(2009) 556-81.
[4] A.P.C. Faaji, Bio-energy in Europe: changing technology choices, Energy Policy
34(2006) 322-42.
[5] Son Yi, A Study on measurement of the light tar content in the fuel gas produced

from small-scale gasification and power generation systems, In: Proceedings of the
15th Annual Meeting of the Japan Institute of Energy; Tokyo: Japan; August 3rd-4th,
2006.
[6] B.R. Thomas, D. Agua, Hand Book of Biomass Downdraft Gasifier Engine System,
Golden Colorado: The Biomass Energy Foundation Press, 1998.
8 | Paper ID :ICP2015-CP141
Page 9 of 13


[7] R. Singh, A.D. Setiawan, Biomass energy policies and strategies: Harvesting potential
in India & Indonesia, Renewable and Sustainable Energy Reviews 22(2013) 332-45.
[8] R. A. Gain, Report (Number-IN2081), Biofuels Annual 2012; India, MNRE. Biomass
Resource Atlas of India; 2009. Biomass data by state 2002-04.
[9] N. Tippayawong, C. Chaichan, A. Promwungkwa, P. Rerkkriangkrai, Clean Energy
from Gasification of Biomass for Sterilization of Mushroom Growing Substrates,
International Journal of Energy 5(2011) 96-103.
[10] H.A.M. Knoef, Inventory of Biomass Gasifier Manufacturers and Installations, Final
Report to European Commission, Contract DIS/1734/98-NL, in, Biomass Technology
Group B.V.,University of Twente, Enschede; 2000, Netherland.
[11] A. Bhavanam, R.C. Sastry, Biomass Gasification Processes in Downdraft Fixed Bed
Reactors: A Review, International Journal of Chemical Engineering and Applications
2(2011) 425-433.
[12] S. Jarungthammachote, A. Dutta, Thermodynamic Equilibrium Model and Second
Law Analysis of a Downdraft Waste Gasifier, Energy 32(2007)1660-1669.
[13] T. H. Jayah, L. Aye, R. J. Fuller, D. F. Stewart, Computer Simulation of a Downdraft
Wood Gasifier for Tea Drying, Biomass and Bioenergy 25(2003) 459-469.
[14] L. Fagbemi, L. Khezami, R. Capart, Pyrolysis products from different biomasses:
application to the thermal cracking of tar, Applied Energy 69(2001) 293-306.
[15] P. R. Wander, C. R. Altafini, R. M. Barreto, Assessment of a small sawdust
gasification unit, Biomass and Bioenergy 27(2004) 467-476.

[16] R.N. Singh, U. Jena, J.B. Patel, A.M. Sharma, Feasibility study of cashew nut shells
as an open core gasifier feedstock, Renewable Energy 31(2006) 481-487.
[17] Pengmei Lv, Chuangzhi Wu, Longlong Ma, Zhenhong Yuan, A study on the
economic efficiency of hydrogen production from biomass residues in China,
Renewable Energy 33(2008) 1874-1879.
[18] V. C. J. Singh, S. J. Sekhar, K. Thyagarajan, Performance studies on downdraft
gasifier with biomass energy sources available in remote villages, American Journal
of Applied Sciences 11(2014) 611-622.
[19] B. Buragohain, P. Mahanta, S. Vijayanand, Moholkar, Investigations in gasification
of biomass mixtures using thermodynamic equilibrium and semi–equilibrium models,
Energy and Environment 2(2011) 551-578.

9 | Paper ID :ICP2015-CP141
Page 10 of 13


[20] P.C. Roy, A. Dutta, N. Chakraborty, Assessment of cow dung as a supplementary fuel
in a downdraft biomass gasifier, Renewable Energy 35(2010) 379-386.
[21] A. Melgar, J.F. Perez, H. Laget, A. Horillo, Thermochemical equilibrium modelling
of a gasifying process, Energy Conversion and Management 48(2007) 59-67.
[22] Z. A. Zainal, R. Ali, C. H. Lean, K. N. Seetharamu, Prediction of Performance of a
Downdraft Gasifier using Equilibrium Modeling for Different Biomasses, Energy
Conversion and Management 42(2001) 1499-515.
[23] P. Basu, Biomass Gasification and Pyrolysis Practical Design and Theory, Elsevier,
Oxford, UK, 2010.
[24] K. Sharma, Equilibrium and Kinetic Modeling of Char Reduction Reactions in a
Downdraft Biomass Gasifier: a Comparison, Solar Energy 82(2008) 918-28.
[25] P.C. Roy, A. Datta, N. Chakraborty, Modelling of a downdraft biomass gasifier with
finite rate kinetics in the reduction zone, Energy Research 33(2009) 833-851.
[26] A.K. Sharma, Experimental study on 75 kWth downdraft (biomass) gasifier system,

Renewable Energy 34(2009) 1726–1733.

Fig.1 Schematic of downdraft gasifier
Fig.2 Schematic of experimental setup
Fig.3 Effect of ф on species concentrationfor coconut shell
Fig.4 Effect of ф on species concentration for rubber seed shell
Fig.5 Concentration of CO along reduction zone with ф of the blend D1
Fig. 6 Concentration of H2 along reduction zone with ф of the blend D1
Fig. 7 Effect of ф on species concentration for the blend D1
Fig.8 Effect of ф on gas production rate for the blends D0, D1, D2 and D3
Fig. 9 Effect of ф on HHV for the blends D0, D1, D2 and D3-Modelling
Fig. 10 Effect of ф on Conversion Efficiency for the blends D0, D1, D2 and D3-Modelling

10 | Paper ID :ICP2015-CP141
Page 11 of 13


Tables

Table 1. Ultimate analysis of biomass (DAF basis)
C

H

O

N

S

MC

HHV

% Wt.

% Wt.

% Wt.

% Wt.

% Wt.

% Wt.

MJ/kg

50.2

5.7

43.4

0

0

5.2

19.83

43.21

6.0

50.25

0.55

0

4.98

17.16

Biomass

Coconut shell
Rubber seed
shell

11 | Paper ID :ICP2015-CP141
Page 12 of 13


Table 2. Different types of blends of biomass materials
Feedstock Combination
Primary

Secondary Energy

Energy Source

Source

Coconut Shell

Rubber Seed Shell

Mole

Blend

Fraction Ratio

Symbol

100:0

D0

90:10

D1

70:30

D2

60:40

D3

12 | Paper ID :ICP2015-CP141
Page 13 of 13