International Journal of Mechanical Engineering and Technology (IJMET)
Volume 10, Issue 01, January 2019, pp. 1371-1382, Article ID: IJMET_10_01_139
Available online at http://www.iaeme.com/ijmet/issues.asp?JType=IJMET&VType=10&IType=01
ISSN Print: 0976-6340 and ISSN Online: 0976-6359
© IAEME Publication
Scopus Indexed
PROSPECTS FOR BIOMASS ENERGY USE IN
THE REPUBLIC OF BURUNDI
J.A. Manigomba, N.D. Chichirova, V.B. Gruzdev, E. Ndikumana, A.I. Lyapin
Institute of thermal power plants, Kazan State Energy University, Kazan, Russia
ABSTRACT
The article considers an alternative replacement of oil fuel for pyrolysis gas and
biogas, obtained from household and industrial waste in the Republic of Burundi. Studies
have been carried out concerning pyrolysis processing of both peat and solid agricultural
waste from rice, sorghum, peas, beans, corn, as well as studies of the biogas production
process from liquid waste from the palm-oil production mini-plant Kirekura-Muzazi in
Bujumbura. Characteristics of liquid wastewaters from the Kirekura-Muzazi mini-plant
were studied, physical and chemical parameters (pH, Alkalinity, DCO, DBO5, MES,
MVS, total nitrogen, DCO/N, dry matter concentration, and humidity) were obtained. The
composition of biogas produced from a mixture of liquid waste from a plant for palm oil
production, waste slaughterhouse, cow manure and pig manure is given. Also the authors
considered the possibility of reconstructing the diesel-electric generating unit of the
industrial group “Regideso” for biomethane with replacement of diesel fuel, which will
increase the service life of the engine, save diesel fuel, create sources of dual fuel, and
improve the operation of the gas-diesel unit without buying special spare parts.
Directions have been proposed to solve the problem of the shortage of primary energy
sources in the Republic of Burundi, and recycling of city and industrial wastes will also
solve environmental problems.
Key words: power plant, mini-plant, biomass, waste, shortage of electric energy, biogas,
ecology.
Cite this Article: J.A. Manigomba, N.D. Chichirova, V.B. Gruzdev, E. Ndikumana and
A.I. Lyapin, Prospects for Biomass Energy Use in the Republic of Burundi, International
Journal of Mechanical Engineering and Technology, 10(01), 2019, pp.1371–1382
http://www.iaeme.com/IJMET/issues.asp?JType=IJMET&VType=10&Type=01
1. INTRODUCTION
Analysis of industrial production of the Republic of Burundi shows that it is experiencing a
significant shortage of electricity. Diesel-electric generators of the energy group “REGIDESO”,
which are widely used in the country, running on hydrocarbon fuel, do not solve this problem [1].
Currently, search for new and use of existing renewable energy sources, in particular, fuels
of biological origin – biomass are now intensified in the world energy sector driven by the rising
prices for fossil fuel produced.
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It follows from [1, 2] that successful application of biomass reserves in the Republic of
Burundi will partially solve the problem with energy fuel, by abandoning diesel fuel, and the use
of bio and pyrogas will improve the thermodynamic and economic efficiency of the existing
diesel-electric generators of the "REGIDESO".
2. WAYS TO SOLVE THE ENERGY PROBLEM OF THE REPUBLIC OF
BURUNDI
In connection with such an acute energy problem, the Government of Burundi offers several ways
to solve it, and one of them is the use of pyrolysis of peat, wood waste, agricultural biomass,
household and industrial waste in order to obtain from them secondary energy resources pyrolysis and bio-gas, diesel fuel, coke, charcoal, heating oil.
In this regard, we carried out studies on the pyrolysis processing of both peat and solid
agricultural waste from rice, sorghum, peas, beans, maize, as well as biogas from solid and liquid
waste from the Kirekura-Muzazi mini-plant in the city of Bujumbura for the production of palm
oil.
2.1. Investigation of pyrolysis biomass processing
We studied the process of pyrolysis of biomass samples in a fixed bed and in a fluidized bed.
Studies in a fixed bed were carried out in a quartz glass retort with external electric heating at a
heating rate of 6–9 ° C/min at temperatures from 450 to 1150 ° C.
Pyrolysis of biomass samples in the fluidized bed was studied in a laboratory setup consisting
of a pyrolyzer with auger feed and external electrical heating. The block diagram is shown in
Figure 1.
Figure 1. Block diagram of the laboratory setup for pyrolysis of solid biomass in the moving layer.
The main elements of the block diagram are: 1 - auger speed control; 2 - gearmotor: 3 - drive
shaft of the rolling auger; 4 - sealing unit with front shaft support; 5 - receiving hopper with
airtight lid; 6 - the main part of the auger body; 7 - electric heater with a capacity of 1.75 kW; 8
- additional removable part of the auger body; 9 – movable auger; 10 - pyrolysis gas filter cooler;
11 - gas analyzer; 12 - receiving flask of solid residue; 13 - thermometers; 14 - electric power
supply to the heater.
Volatile products formed as a gas-vapor mixture in the reaction zone of this installation are
discharged into the cooling and cleaning system 10, then into the gas analyzer 11, and the solid
residue (coke) is collected in the receiving flask 12.
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The studied types of biomass have almost the same elemental composition of C, H2 and O2.
The study of the laws of thermochemical transformations of rice straw, peat and wood, which
are observed during pyrolysis and combustion, was also carried out by thermal analysis in
different modes using the Q-1500D derivatograph and experimental installations in a stationary
and moving bed at different heating rates, performed in the Burundi State Laboratory ScientificAgrochemical Institute (ISABU), Bujumbura.
All experiments were conducted in closed rooms at air temperatures of 24-26 °C.
Thermocouples with a junction diameter of 0.2 mm were used to record the sample temperatures.
Samples were weighed on the OHAUS, PA 214C analytical balance. The samples were cooled
in a laboratory desiccator. The samples were burned in the Carbolite RHF 1406 furnace at 8
different temperatures - 450, 550, 650, 750, 850, 950, 1050, 1150 ° C.
It is known that the difference between the initial weight and the weight at a certain
temperature, divided by the initial weight, and expressed as a percentage, gives the release of
volatile gases from the sample under study.
The measurement data were put into Table, and four graphs were created (Fig. 2).
Two methods were used to study volatile gas samples.
1. The method for raw samples, when all samples without drying were simultaneously put in
a cold furnace, heated to 450 ° C, kept for 5 minutes. Then the furnace was turned off, all samples
were removed from it, cooled in a desiccator, weighed using the OHAUS, PA 214C analytical
balance, then again placed in the furnace, set the desired 8 temperatures, and turned on the
furnace. But since the temperature in the furnace has already decreased, in this case the burning
time could increase, so we recorded the 5-minutes time from the time the furnace reached the
desired temperature.
2. The method for the annealed samples, when the dried sample, after determining its initial
humidity in the first method, was placed in two parallel portions separately from the others into
the furnace, preheated to the required temperature. After 5 minutes the samples were removed
from the furnace, cooled in the desiccator and weighed using the OHAUS, PA 214C analytical
balance. The results of the measurements were put in Table and the plots were created (Fig. 2).
Figure 2. Relationship between the partial output of pyrolysis gas from various wastes and the furnace
temperature.
As the studied raw material for pyrolysis we used the following waste:
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•
Graph 1 is a series of 8 experiments for waste from rice, coffee straw, waste husk, the
initial humidity is 6%;
•
Graph 2 is a series of 8 experiments from rice straw and waste wood, the initial humidity
is 6%;
•
Graph 3 is a series of 8 experiments from peat A, the initial humidity ≈ 6%;
•
Graph 4 is a series of 8 experiments from peat B, the initial humidity ≈6%;
It is known that the composition of the pyrolysis gas mainly includes gases CO and H2. But
depending on the method of its production, the CO: H2 ratio varies from 1:1 to 1:3. In direct
dependence with raw materials used and the method of its processing, the ratio of these
components can vary widely. As a rule, the percentage of substances in raw gas, unrefined by
pyrolysis, is the following: CO is 11-18%; H2 is 12-28%; CH4 is 33-45%; CO2 is 1.5-2.5%.
Table 1 shows the average composition of the pyrolysis gas derived from biomass, and its
energy value.
Таble 1. Average content of the obtained pyrolysis gas from municipal solid waste
No.
Pyrolysis gas content
Component content,
%
Calorific capacity (lowest),
MJ/m3
1
2
3
4
Methane (СН4)
Hydrogen (Н2)
Carbon oxide (СО)
Carbon dioxide (СО2)
33 – 45
12 – 28
11 – 18
1.5 – 2.5
Total:
35.80
10.80
12.64
59.24
The objective of our study was to maximize the production of pyrolysis gas as a fuel from biomass
and peat to ensure the operation of diesel-electric generators of the industrial group
"REGIDESO".
2.2. RESULTS OF THE STUDY OF THE PROCESS OF OBTAINING BIOMASS
PYROLYSIS PRODUCTS
According to the results of calculations and literature analysis [3-5], it is possible to make a
reasonable conclusion that the main characteristic of the processes of controlled thermal
decomposition of biomass is composition of the products of its thermal conversion. Therefore, as
the aim of the planned experiments we have chosen the composition of the final (to a certain point
in time, corresponding to the achievement of a fixed temperature) products (solid, liquid and
gaseous).
The main variable factors determining this composition are the sample temperature at the end
of a single experiment, the heating rate, biomass type of, and the temperature range.
The choice of the temperature range was carried out by a simple iteration method when the
conditions of complete conversion were reached.
The values of the heating rate were chosen based on the real possibilities of the installation
for the industrial thermal conversion of biomass.
The intervals of temperature changes were chosen on the basis of conditions that ensure
maximum reliability of the experimental results.
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The main types of biomass promising for use in Burundi were used in our research: the
Burundi palm sawdust, local peat from two deposits A and B, rice and coffee straws and husks.
In preliminary experiments it was found that, despite the high demands on the stability of
conditions of a single experiment for all significant factors, some dispersion of experimental data
took place.
For this reason, the number of experiments with fixed factors was chosen at least eight. At
the experimental facility, the process of pyrolysis of dry sawdust and peat was conducted in the
temperature range from 450 to 1150 °C and it was found that the total yield of the gaseous
pyrolysis phase in the studied temperature range significantly depends on the temperature in the
furnace and reaches its maximum during pyrolysis of peat B, with humidity no more than 6%.
The analysis of curves in fig. 2 shows that waste from rice straw and husk (series 1) with a
significant increase in temperature in the furnace, has a rather sluggish yield of volatile gases, but
at a temperature of 1000 °C it begins to rise sharply and reaches its maximum of about 93%. The
further increase in temperature in the furnace does not lead to an increase in the volatile yield of
the sample.
A similar intensity of volatile gases is observed in series 2, but with further increase in
temperature over 650 °С, the value of volatile gases continues to remain at 62%.
Hence we can conclude that in a series of experiments 1 for rice straw and husk, which have
a slightly dense structure of plant tissue and a high content of air, firstly in the temperature range
(550 - 850 °С) the concentration of the volatile gases is stabilized, and then a jump increase in
conversion occurs with an increase in the volatile gas yield from 82% to 93%.
The experimental series 3 showed that the pyrolysis of briquette from peat A leads to a
delayed biomass decomposition reaction, but with increasing temperature, the volatile yield
continues to increase and reaches its maximum of 61% at a furnace temperature of 1150 ° C.
Series 4 showed that the briquette from local peat B has a more intensive rate of release of
volatile gases, which begins to grow from 550 to 750 °C, i.e. The rate of volatile release in this
range was 1% for every 40 °C of the reactor temperature increase. Further temperature increase
in the reactor no longer leads to an increase in the volatile gas yield from the sample.
The obtained pyrogas from this waste and peat of type B has a real use as a fuel for gas-diesel.
But in order to bring it to the quality of natural gas, a better cleaning is needed to eliminate
harmful liquid (distillate) and solid fractions, which will slag the fuel supply working chamber in
a diesel engine. Nevertheless, further deep processing of pyrolysis distillate makes it possible to
obtain various commercial fuel products, such as diesel fuel, gasoline, kerosene, fuel oil, and
solar oil, which are highly relevant for the national economy of Burundi.
2.3. Investigation of biogas processing of seed meal from palm oil production
As a source of biogas, we investigated the waste of palm oil production at the mini-plant
"Kirekura-Muzazi" in the city of Bujumbura. The biomethane unit, installed at the operating
mini-plant, consists of four reactors D1, D2, D2 and D4, where the raw material from palm fruits
after extracting palm oil from them, turns into palm meal.
Reactors are filled with nutrient substrate at least 4 times a week. The active fermentation
substrate itself consists of cow and pig manure, as well as slaughterhouse waste.
An analysis of the anaerobic process in the digesters led to the conclusion that, if the feed
consists of a balanced substrate consisting of carbon and nutrients, as well as anaerobic
microorganisms, the biogas recovery process will be more intensive.
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It was for this purpose and to ensure the quality of the feed for the reactors, we carried out
studies of the characteristics of liquid effluents from the Kirekura-Muzazi mini-plant, physicchemical parameters of which are given in Tables 2-11.
The composition of biogas and the content of CH4, CO2 and H2S in biomethanization was
studied and evaluated by laboratory sampling for chemical analysis from bioreactors and
digesters.
Table 2. The results of determining the characteristics of liquid waste of the palm oil production plant
and its production to power the reactors.
Parameter of waste from the plant for
powering the bioreactors, determined
during investigations
Value
VDI,
Standard 4630
pH
Alkalinity (mg-eq /l CaCO3 )
DCO (mg О2 / l)
DBO5 (mg О 2 / l)
MES (mg / l)
MVS (mg / л)
Total nitrogen (Ntotal ), (mg/l)
DCO / N
Moisture level (%)
6.8 ± 0.2
1120 ± 12
35000 ± 2018
13800 ± 960
8100 ± 57
6700 ± 85
1011 ± 15.2
34.6
97.33 ± 0. 7
6.8-7.4
> 1000
30 - 35
Min - 65%
Table 3. Biogas content, which is produced from liquid waste of the plant of the palm oil production
Gas
Gas content, %
СН4
CO2
H2S
64 ± 1.2
35.1
0.1
Table 4. The results of determining the characteristics of liquid waste of the palm oil production with
cow manure to power the reactors.
Parameter of waste from the plant for
powering the bioreactors, determined
during investigations
Value
VDI, Standard
4630
pH
Alkalinity (mg-eq /l CaCO3 )
DCO (mg О2 / l)
6.8 ± 0.2
1160 ± 12
37000 ± 20000
6.8-7.4
>1000
-
DBO5 (mg О 2 / l)
MES (mg / l)
MVS (mg / л)
14000 ± 960
10000 ± 60
8400 ± 30
-
Total nitrogen (Ntotal ), (mg/l)
1080 ± 18
DCO / N
34.25
30 - 35
Concentration of dry content, (%)
2.68 ± 0 3
˂15%
Moisture, (%)
9 7.32 ± 0. 7
Min 65%
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Table 5. Biogas content, which is produced from liquid waste and cow manure at the plant of the palm
oil production to power the bioreactor.
Gas
Gas content, %
СН4
CO2
H2S
69 ± 1.2
30.1
0.13
Table 6. The results of determining the characteristics of liquid waste of the palm oil production with
pig manure to power the reactors.
Parameter of waste from the plant for
powering the bioreactors, determined
during investigations
Value
VDI, Standard
4630
pH
Alkalinity (mg-eq /l CaCO3 )
DCO (mg О2 / l)
DBO5 (mg О 2 / l)
MES (mg / l)
MVS (mg / л)
Total nitrogen (Ntotal ), (mg/l)
DCO / N
Concentration of dry content, (%)
Moisture, (%)
7 ± 0.2
1118 ± 14
34000 ± 2017
13900 ± 960
8200 ± 57
6830 ± 40
1016 ± 15.4
33.46
2.66 ± 04
9 7.33 ± 0. 6
6.8-7.4
>1000
30 - 35
˂15%
Min 65%
Table 7. Biogas content, which is produced from liquid waste at the plant of the palm oil production and
pig manure suspension to power the bioreactor.
Gas
Gas content, %
СН4
CO2
H2S
65 ± 1.3
34.1 ± 1.7
0.1
Table 8. The results of determining the characteristics of liquid waste of the palm oil production with
slaughterhouse waste to power the reactors.
Parameter of waste from the plant for
powering the bioreactors, determined
during investigations
Value
VDI, Standard
4630
pH
Alkalinity (mg-eq /l CaCO3 )
DCO (mg О2 / l)
DBO5 (mg О 2 / l)
MES (mg / l)
MVS (mg / л)
Total nitrogen (Ntotal ), (mg/l)
7.1 ± 0.1
1150 ± 15
30500 ± 2118
14800 ± 1000
10000 ± 55
8500 ± 40
950 ± 29.9
6.8-7.4
> 1000
-
DCO / N
Concentration of dry content, (%)
Moisture, (%)
32.1
4.93 ± 0.6
95.07 ± 0.4
30 - 35
˂15%
Min 65%
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Table 9. Biogas content, which is produced from liquid waste at the plant of the palm oil production and
slaughterhouse waste (scar content)
Gas
Gas content, %
СН4
CO2
H2S
70 ± 1
28 + 12
0. 05
Table 10. The results of determining the characteristics of liquid waste of the palm oil production with
slaughterhouse waste, cow and pig manure to power the reactors.
Parameter of waste from the plant for
powering the bioreactors, determined
during investigations
Value
VDI, Standard
4630
pH
Alkalinity (mg-eq /l CaCO3 )
DCO (mg О2 / l)
DBO5 (mg О 2 / l)
MES (mg / l)
MVS (mg / л)
Total nitrogen (Ntotal ), (mg/l)
6.9 ± 0.1
1050 ± 15
30000 ± 2018
13800 ± 960
8100 ± 57
6630 ± 43
10000 ± 29.9
6.8-7.4
> 1000
-
DCO / N
Concentration of dry content, (%)
Moisture, (%)
30
4.93 ± 0.6
95.07 ± 0.4
30 - 35
˂15%
Min 65%
Table 11. Biogas content, which is produced from liquid waste at the plant of the palm oil production,
slaughterhouse waste (scar content), cow and pig manure.
Gas content, %
СН4
CO2
H2S
68 ± 1.2
31.1
0.1
Gas content in the volume of biogas,
%
Gas
Figure 3. Experimental histogram of gas content in the volume
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•
•
•
•
•
Category 1 (Experiment No. 1). The composition of biogas obtained from liquid waste of
the palm oil production plant.
Category 2 (Experiment No. 2). The composition of biogas obtained from liquid waste of
the palm oil production plant and cow manure.
Category 3 (Experiment No. 3). The composition of biogas obtained from liquid waste of
the palm oil production plant and pig manure.
Category 4 (Experiment No. 4). The composition of biogas obtained from liquid waste of
the palm oil production plant and waste slaughterhouse (scar content).
Category 5 (Experiment No. 5). The composition of biogas obtained from liquid waste of
the palm oil production plant, cow manure, pig manure and slaughterhouse waste.
2.4. Conclusions on the results of experiments at a mini-plant in the city of
Bujumbura, Republic of Burundi, performed in 2018
To obtain more objective conclusions on the results of the analysis of experiments, we take as a
basis the German standard “VDIRICHILINIEN (VDI 4630), which is the international standard
for anaerobic plants in the production of biogas from biomass [4].
According to the analysis of the samples, it was found that the raw materials in the reactors
are oxygen-rich, which is balanced with nitrogen, which corresponds to the standard
“VDIRICHILINIEN (VDI 4630).
Chemical oxygen index (DCO) characterizes the necessary oxygen demand and indicates a
high concentration of carbon in the substrate, which is processed in a biogas plant. The higher is
the value of this indicator, the greater the ratio of oxygen to nitrogen (DCO/N) is, and the closer
it is to the proposed ratio in the standard (DCO/N = 30 - 35), which indicates an increase in the
mass of the substrate introduced into the reactor used in production of biogas.
The biochemical oxygen index (DOB5) indicates the carbon content transformed by
microorganisms in the substrate involved in the biogas process. The higher the value of this
indicator, which is close to DCO for the same substrate (about 80% DCO), the better food the
substrate is for microorganisms involved in the process of biogas production. In our case, a
decrease in DOB5 by more than 70% from DCO indicates that the substrate used is good food
for microorganisms.
The parameter determining the yield of volatile substances (gaseous parameter of biomass)
shows that substances present in the form of an organic suspension can be activated by
microorganisms involved in the bioprocess.
The closer is this parameter to suspended solids (MES), the higher effect we will achieve in
the process of biogas production, while volatile suspended particles (MVS) are in the range from
82 to 85% in a conglomerate with solids, which proves the usefulness of wastewater nutrient
medium for microorganisms, so it is necessary to increase the amount of substrate rich in carbon
and nitrogen, and then sources of microorganisms (for example, fresh cow manure or pig
manure).
The higher is the moisture content in the substrate, the better is the contact of the substrate
with microorganisms, which ensures good biogas production.
The standard requires that the moisture in the substrate is at least 65%. In our case, this level
is higher, which allows us to explain the high productivity of biogas production.
The method for determining the above indicators is described in detail in the standard
"VDIRICHILINIEN (VDI 4630)" and in [5-7].
The presence of hydrogen sulfide (H2S) in biogas, as a chemically aggressive gas, is
practically unacceptable, and according to the norms of the standard, its value should not be more
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than 0.1% of the total biogas volume. In our experiment, we fit into this norm. But one still need
to find ways to reduce it. Since this paper provides for the methane (CH4) usage for the
production of electrical energy, a special biogas treatment is needed, including continuous
filtration of the entire biogas flow, including that from hydrogen sulfide.
From a mixture of biogas obtained from five experiments, it follows that the methane content
is more than 70%, and the content of various negative impurities is below the norm.
All this allows us to conclude that according to the energy value, methane gas obtained from
the biomass considered by us may well replace diesel fuel in diesel generators, and thereby
partially solve the energy problem in the Republic of Burundi.
3. PROSPECTS FOR THE USE OF PYRO- AND BIOGAS IN THE
ENERGY SECTOR OF THE REPUBLIC OF BURUNDI
Currently, three diesel power plants are operating in the Republic of Burundi - “Buja - 1, 2, 3”,
which, with an installed electrical capacity of 20 MW, consume about 6000 kg of diesel fuel per
hour [2].
All petroleum products in Burundi are purchased in Tanzania, Congo and Kenya at a cost of
one kilogram of more than $1.0. Thus, the annual cost of diesel fuel is about $50 million. So, 1.0
kWh of electricity costs $0.36 or 25 rubles at the maximum installed capacity utilization factor
(ICUF) = 0.8. Unfortunately, the prices of oil and petroleum products are constantly increasing,
especially for energy-deficient countries. Therefore, we will consider the technical possibility of
using biogas for the reconstruction of diesel-electric generators in operation at the industrial
group “REGIDESO” in the city of Bujumbura, the Republic of Burundi.
3.1. Reconstruction of fuel supply diesel-electric generator for biomethane usage
For practical calculations of reconstruction of diesel-electric generators for new fuel biomethane, one can use a guaranteed degree of substitution of 70-75% of diesel fuel, while the
efficiency of a gas-diesel engine will be higher than the efficiency of the original engine, by about
3-5%. This is due to the external mixing of the gas-diesel engine, which makes it possible to
obtain a homogeneous mixture in the intake tract from the fuel injection system. This increased
efficiency allows one to substitute each saved liter of diesel fuel by approximately 1.0m3 of
methane.
Converted diesel engine retains the ability to work on diesel fuel and in the absence of
pyrolysis gas.
But it is possible to reconstruct diesel generators, in which an ignition system (spark plugs)
is installed on a converted diesel engine, so the gas diesel engine becomes a gas engine operating
in the Otto cycle [8]. In this case, the possibility of working on diesel fuel is missing. In our
conditions, the second reconstruction option is unacceptable.
For the possible use of biomethane in diesel generators of "REGIDESO", it is necessary to
install special fuel equipment (evaporator and heater of biomethane, gearbox, gas-air mixer).
Since the ignition temperature of the gas-air mixture from compression in the cylinder of a
conventional diesel engine is about 700 °C, and the diesel fuel itself is ignited at 320–380 °C, the
high-pressure fuel pump and the injectors are preserved, and the engine ignition dose is supplied
to the engine cylinders (about 15-30% of the nominal value before the reconstruction).
3.2 Advantages of the reconstructed diesel engine
Reconstruction of diesel generators for gas diesel will allow:
1. To increase the engine's life by reducing the pressure in the high-pressure liquid fuel
compressor, since the system is equipped with sensors for monitoring the temperature
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2.
3.
4.
5.
of the exhaust gases, which helps prevent the engine from overheating and thus avoid
its detonation;
To maintain the engine power, although if it is necessary, one can increase its torque;
To save diesel fuel by 70-85% due to the transfer of engine to the gas-diesel mode;
To create sources of dual fuel, as in case of emergency termination of the biogas supply,
the automatic device switches the fuel system to diesel fuel;
To service the gas-diesel unit without buying special spare parts, since all the spare parts
for the engine remain regular.
4. CONCLUSIONS
1. The conducted experiment of 4 series with 8 temperature measurements aimed at
determining the share of volatile gases from the wastes of the main industrial fuels used in the
Republic of Burundi showed that it is realistic to use enough waste and local type B peat to
produce enough pyrolysis gas for successful works of diesel generators of the industrial group
"REGIDESO".
2. Fast and high-temperature pyrolysis allows one to preserve the energy capacity of rice,
coffee straw and husk, as well as Burundian palm trees, and thereby increase the yield of volatile
gases for a longer time during high-temperature conversion;
3. With the help of the experiment, the important role of the influence of the temperature of
the gasification process on its results, especially on the yield of pyrolysis gas from local peat
species was determined.
4. A threshold temperature was also established (450 ºС), at which there is a sharp increase
in the gas yield from peat of type B and, as a result, an increase in its volume and calorific value.
5. In general, it was determined that with an increase in the conversion temperature, there is
an improvement in the basic parameters of the pyrolysis gas produced from local types of
biomass, which is especially important for diesel generators with a significant power shortage in
the Republic of Burundi.
6. Biogas obtained from a palm liquid substrate in the Kirekura-Muzazi mini-plant in the city
of Bujumbura, Republic of Burundi, contains: CH4 - more than 70%; H2S - about 0.1%; CO2 about 30%. This indicates that the resulting biogas, with methane content of more than 70%, may
well be used as fuel for generating electricity in diesel generators, and for domestic purposes.
7. The results of 5 experiments on the production of biogas allow us to conclude that mixing
the substrate with waste of the palm oil plant and waste from the slaughterhouse, allows one to
obtain biogas of the following composition: CH4 - 70%; H2S -0.5%; CO2 - 28%.
8. Substrate consisting of a mixture of palm oil and cow manure production, allows one to
obtain biogas of the following composition: CH4 - 69%; H2S - 0.1%, CO2 - 30%.
9. Substrate consisting only of waste oil from palm oil, allows one to obtain a mixture of
biogas of the following composition: CH4 - 64%; H2S-0.13%; CO2 - 35%. If we consider this
mixture as an energy fuel, then 64% of methane allows us to speak about its practical application,
since according to the standards for diesel generators, methane should be in the range of 50 to
70%. But the increased content of hydrogen sulfide (0.13%) indicates poor quality of the initial
palm raw material in the cooking boilers. Special purification of the entire volume of biogas from
hydrogen sulfide will allow it to be successfully applied in industry and in everyday life.
10. As it follows from the results of experiments, the degree of acidity (pH) in the reactors is
close to the norm (6.8-7.4), but adding lime to the liquid substrate at a certain concentration will
allow intensifying both chemical and biological fermentation processes, and increasing the output
of biogas from the substrate.
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J.A. Manigomba, N.D. Chichirova, V.B. Gruzdev, E. Ndikumana and A.I. Lyapin
11. Considering the amount of gas produced every day at the operating mini-plant that
processes 6.0 tons per day of palm raw materials, it can be concluded that with full automation
and intensification of the cooking process it becomes possible to increase productivity by several
times and thus to approach the production of biogas to the existing industrial plant in Europe,
which will at least partly solve the energy problem in the Republic of Burundi;
12. The results of the reconstruction of diesel generators of the industrial group “REGIDESO”
to the use of biomethane as fuel will increase their engine life, as well as reduce the consumption
of diesel fuel by 55-60%, and thereby reduce the cost of electricity supplied by 2.0-2 5 times
[9,10].
REFERENCES
[1]
[2]
[3]
[4]
[5]
[6]
[7]
[8]
[9]
[10]
[11]
[12]
[13]
[14]
[15]
[16]
Manigomba, J.A., Chichirova, N. D. Organization of the electric power industry of the
Republic of Burundi. Proceedings of Academenergo, 4, 2015, pp. 121-123;
Manigomba J.A., Chichirova N.D. Prospects for the use of organic and industrial waste in the
energy sector of the Republic of Burundi. Proceedings of Academenergo, 2, 2017, pp. 107110;
Rapport de production d’électricité entre 1996-2014. Service équipement électricité de la
REGIDESO, 2015, pp. 15-18
VDI-RICHTLINIEN. Fermentation of organic materials. Characterization of the substrate,
sampling, collection of material data, fermentation tests. 2016, pp. 113-115.
Gas-generating technologies. Business forest, 3(63), 2006 pp. 60-62;
Substrate, sampling, collection of material data, fermentation tests 2016-P113-115.
E-I-7v1: Détermination de la demande chimique en oxygene (DCO). CWEA 2014, pp. 6-8.
Protocole de determination des parametres physico chimiques et bacteriologiques. Center
régional pour l’eau potable et l’assainissement à faible coût. Ouagadougou: EAA - Eau et
Assainissement pour l'Afrique, 2007, pp. 21-32.
Rapport de projet de production. Ministère de l’énergieet des mines, 2013, 26-30;
Malicet, R. Guide d'exploitation des chaudières, Matériels-Equipements, Automatismespollution, Sécurité-Economie, deuxième édition revue et complétée. Paris: MassonEditeur,
1980;
Rapport de production d’électricité entre 2001-2007. Service équipement électricité de la
REGIDESO, 2015, pp. 116-117.
C. O. Osueke, T. M. A. Olayanju, C. A. Ezugwu, A. O. Onokwai, I. Ikpotokin, D. C. UguruOkorie and F.C. Nnaji, Comparative Calorific Evaluation of Biomass Fuel and Fossil Fuel,
International Journal of Civil Engineering and Technology (IJCIET) 9(13), 2018, pp. 1576–
1590.
Manish Kumar, Bireswar Paul and Dhananjay Singh Yadav, Effect of Moisture Content and
Equivalence Ratio on the Gasification Process for Different Biomass Fuel. International
Journal of Mechanical Engineering and Technology, 7(6), 2016, pp. 209–220.
M. Ramarao and S. Vivekanandan, Evaluation of Carbon Conversion Efficiency of Mixed
Biomass Gasification. International Journal of Mechanical Engineering and Technology, 7(6),
2016, pp. 555–564.
K.J. Sharmila and RM. Narayanan. Evaluation of Primary Production and Fish Biomass along
Chennai Coast Using Field and Empirical Algorithms. International Journal of Civil
Engineering and Technology, 8(12), 2017, pp. 751-762.
B.J.M. Rao, K.V.N.S. Rao and G. Ranga Janardhana, Experimental and Computational
Investigation of Mixing Behaviour of Biomass with Inert Sand in Fluidized Bed, International
Journal of Mechanical Engineering and Technology 8(9), 2017, pp. 257–263.
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