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A. Tamosiunas et al. / C. R. Chimie xxx (2016) 1e8
2
reaching up to 15000 K [16], offer a possibility to advan-
tageously contribute to the pyrolysis/gasification of organic
materials by accelerating the reaction kinetics. The easiest
enthalpy control by adjusting the electric power and flow
rate of the plasma-forming gas allows controlling the pa-
rameters of the conversion process in situ. The production
of reactive species by the plasma, such as atomic oxygen,
hydrogen and hydroxyl radicals, is an additional advantage
of using plasma [17]. However, the maturity of thermal
plasma in terms of economic feasibility has not been
proved yet because of the use of expensive electrical energy
to run plasma torches.
parameters including the water steam flow rate, the treated
material flow rate and the plasma torch power were
studied. The modeling of chemical processes, based on a
classical thermodynamic equilibrium reactor model (TER),
was also proposed. Furthermore, the quantification of the
plasma conversion system in terms of energy efficiency and
a specific energy requirement was performed. It was found
that the synthesis gas with a high content of H2 and CO
could be effectively produced from glycerol and wood by
the thermal water steam plasma pyrolysis/gasification
process.
The oxidation environment in the waste treatment
process is also an important feature. Knoef [18] shows the
differences obtained between two different oxidation
agents used (pure oxygen and air). Pure oxygen provides a
gas with a calorific value of 10.1 MJ/m3, while the use of air
gives only 4.2 MJ/m3 due to the dilution of the synthesis gas
with nitrogen introduced with the airflow. Water steam is
generally preferred, because it produces the desired re-
actions including the steam reforming reaction and in-
creases the H2 ratio in the synthesis gas. However, the
steam reforming reaction is highly endothermic and needs
a high temperature (1100e1700 K) [19].
2. Experimental setup and methods
2.1. Design of the biomass conversion system
In this study, the conversion of glycerol and wood to
synthesis gas was carried out using an entrained bed
plasma-chemical reactor (PCHR). The experimental system
is shown in Fig. 1.
It consists of an atmospheric pressure DC arc plasma
torch, a power supply system, a steam generator, a super-
heater,
a gas supply system, a chemical reactor, an
Numerous investigations have been carried out
employing thermal plasma (DC e direct current, AC e
alternating current, RF e radio frequency, and MW e mi-
crowave) with a different type of plasma-forming gas for
biomass/waste conversion to energy. References [20, 21]
investigated the pyrolysis/gasification of biomass and
organic material supply, a condenser with silica gel (to
remove moisture from the gas produced), and a gas chro-
matograph. The entrained bed plasma-chemical reactor
used in this study was 1 m long with 0.4 m inner diameter.
At the bottom of the reactor, there is a section for the
removal of char and condensed water, and in the middle an
outlet chamber for the produced gaseous products is
installed. The residence time varied from 0.5 to 1 s, which
depended on the flow rates of steam and the treated
organic material, and the size of the PCHR.
Pure glycerol (99.5%) was used as a substitute for crude
glycerol, which is considered a by-product of biodiesel
production after the transesterification process. Glycerol
was supplied to the chemical reactor at a constant rate of
2 g/s through the special spray nozzles. The optimal oper-
ating pressure of a spray nozzle is 10 bar. Therefore, the
pressure in the glycerol feeding line was kept at 10 bar and
regulated by nitrogen gas from a cylinder. To improve the
fluidity and spray stability of glycerol, it was preheated to
343 K with a heater before supplying to the reactor.
Wood was chosen as a solid organic material because of
the known chemical composition: C e 50.25%, H e 6.09%, O
e 43.35%, N e 0.2%, and S e 0.1% [22]. It was supplied to the
reactor by a special feeder at the flow rate of 1.2 g/s.
An atmospheric pressure DC arc plasma torch was used
to generate active plasma radicals (O, H, and OH) from the
water steam. The power of the plasma torch depends on
the current intensity, voltage, and the flow rate of the
plasma-forming gas. Argon was used as a shielding gas in
order to protect the tungsten cathode of the plasma torch
from erosion. During the experiments, the plasma torch
power was changed from 48 kW to 56 kW (current 200 A,
voltage 240e280 V, steam flow rate (at 500 K) 2.63e4.48 g/
s). The mean temperature in the plasma-chemical reactor
was simply calculated from the heat balance equation
corresponding to the plasma enthalpy. The methodology is
concisely defined in [27]. During the experiments, the
waste for synthetic fuel production using
a hybrid
argonewater stabilized DC plasma torch. It was found that
the synthesis gas with a high caloric value, a high content of
hydrogen and CO, and a low concentration of CO2 was
produced. An AC plasma torch stabilized with an air stream
was used for wood gasification in [22]. The authors claim
that 1 kg of wood with a moisture content of ~20% can
generate ~13.5 MJ/kg of chemical energy with an energy
consumption of ~2.16 MJ/kg. The MW plasma gasification of
glycerol was performed in [23]. It was found that, at a zero
O2/fuel ratio, it is possible to produce the syngas with a
high H2 and CO content of 57% and 35%, respectively.
Additionally, when the steam/fuel ratio increased, the H2
content in the syngas increased, whereas the syngas
heating value and gasification efficiency decreased. The
pyrolysis of waste tire powder in a capacitively coupled RF
plasma reactor under reduced pressure was studied in [24].
The results suggested that the pyrolysis of polymeric waste
may be a feasible technique for recycling polymer waste.
The gaseous product contains a large amount of H2 and CO
and a small amount of methane and other light hydrocar-
bons. The gasification of municipal solid waste using the
pilot-scale Plasma Gasification Melting (PGM) process is
reported in [25]. The syngas lower heating value (LHV)
varied from 6 to 7 MJ/Nm3. The production of a high-purity
H2 (>99.99%) from the thermal plasma gasification of paper
mill waste is shown in [26].
In this study, a thermal DC arc discharge water steam
plasma was used to pyrolyze/gasify organic materials to
synthesis gas. Glycerol and crushed wood were used as a
source of biomass. The effects of different conversion
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Please cite this article in press as: A. Tamosiunas, et al., Biomass conversion to hydrogen-rich synthesis fuels using water steam