Energy and Power Engineering, 2013, 5, 315-318
doi:10.4236/epe.2013.54B062 Published Online July 2013 (http://www.scirp.org/journal/epe)
Experiment Research on Gasification Character of
Pulverized Coal at Medium Temperature
Tong Lou1, Zhon g-xiao Zhang1,2, Jun-jie Fan2, Hai-quan An2, Zhi-hao Zhou1, Pu-jie Yue1
1College of Environment and Architecture, University of Shanghai for Science and Technology, Shanghai, China
2School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai, China
Email: zhzhx222@163.com
Received March, 2013
ABSTRACT
In this paper, effect of gasification temperature and residence time on gasification characteristics of typical pulverized
coals under atmosphere pressure were studied on a one-dimensional electric heating drop tube furnace system to evalu-
ate gasification characteristics of pulverized coal at medium temperature. The results show that the gasification rate
increases with the raising of the gasification temperature under the temperature among 1150℃ and 1450℃, and as the
temperature is above 1350℃, the increasing rate become slower. Cold gas efficiency and carbon conversion meet the
maximum value when the temperature approaches the ash fusion point of coal. With the further rise of the temperature,
ash on the surface of the char starts to be melted, the gasification reaction rate decreases, due to the hindrance of the
effective contact between coal char and gasification agent. The gasification efficiency would become steady when the
residence time exceeds 8s.
Keywords: Gasification Characteristic; Pulverized Coal; Carbon Conversion; Cold Gas Efficiency
1. Introduction
Issues on natural resource and environment become in-
creasingly severely in China, due to the long-term use of
traditional coal combustion. Integrated gasification com-
bined cycle (IGCC) takes advantage on high efficient and
environmentally-friendly, is a new power generation
technology. Gasified is one of the key devices of IGCC
power generation system. Compared to the other gasifi-
cation technologies, entrained flow gasification technol-
ogy get rapid development for its advantages of high
gasification intensity, high carbon conversion and be
easily practiced on a large scale. Influencing factors on
gasification efficiency of entrained flow gasified are
many, effect of gasification temperature and residence
time on gasification characteristics of typical pulverized
coals were studied on a one-dimensional electric heating
drop tube furnace system under the conditions of atmos-
phere pressure and medium temperature from 1150 to
1450℃[1-3].
2. Experimental System and Work
Conditions
2.1. Experimental System
Figure 1 is the picture of experimental system, which is
consisted of high temperature tube electric heating fur-
nace, ash collected system and syngas cleaned and de-
tected system. The furnace is made of corundum tube(2.1
m in length, 60 mm in inner diameter), the adjust tem-
perature is up to 1550℃, the gas analysis equipment is a
infrared gas analyzer produced by Wuhan Cubic Opto-
electronics Technology Co., Ltd., which can proceed real
time measurement on CO, CO2, H2, CH4 and O2.
Figure 1. The schematic picture of the experimental process.
Copyright © 2013 SciRes. EPE
T. LOU ET AL.
316
2.2. Work Conditions
Datong bituminous coal, a typical bituminous coal in
China was selected for the experiment on gasification
characteristic of pulverized coal at medium temperature,
and effect of gasification temperature and residence time
were mainly considered. The average particle size of
pulverized coal is more or less than 100 µm (under 150
µm) and the feeding rate is about 0.2 kg/h. The proxi-
mate analysis and the elemental analysis of the coal is in
Table 1, the experimental operating conditions are in
Table 2.
2.3. Experimental Data Processing Methods
It’s relatively difficult to measure the syngas directly as
its high temperature. So the total amount of dry gas could
be obtained by the calculation of N2 balance, the divided
relationship between the N2 amount in the inlet and the
N2 percentage of dry gas in the outlet: 2
2
,in N
N
Q
Q
, the-
reinto, Q is the flow of syngas, is the flow of N2
2
,in N
Q
amount in the inlet, 2
N
is the gas volume fraction of
N2 in the dry gas.
As the experiment proceeded in one-dimensional drop
tube furnace, residence time of pulverized coal staying in
the furnace is equal to the residence time of reactivity
gas:
Table 1. Proximate analysis and the elemental analysis of
the datong coal.
Coal Datong
Mad 1.61
Aad 26.89
Vad 28.26
Proximate analysis%
FCad 42.34
Cad 77.78
Had 5.39
Oad 12.79
Nad 1.09
Ultimate analysis%
Sad 2.69
DT 1350
ST 1370
Ash fusion temperature(℃)
FT 1400
Table 2. The Experimental operating conditions.
Pressure Temperature
(℃)
Residence time
S
Ratio of
O/C
1atm
1150
1250
1350
1450
10
8
6
4
3
1:1
22
2
,,
288
(273 )()
inNin O
lr
tTQ Q

,
thereinto, L is the length of the furnace, r is the inner
diameter of the furnace, T is the temperature of the fur-
nace; and is the flow of O2 in the inlet.
2
,inO
Oxygen element of the gas products is mainly from
pulverized coal and the injected O2 in the inlet, such as
CO, CO2 and H2O. Therefore, the amount of vapor in the
syngas can be calculated by the balance of O2 element,
the amount of vapor in the syngas(mol) = oxygen amount
of the injected O2 + oxygen amount of coal – the amount
of the oxygen element from carbon dioxide and carbon
monoxide in the gas, the calculation formula is
Q
22
2
22
,
,
222.416 222.422.4
222.416 222.422.4
100%
in OCCOCO
HO in OCCOCO
QMQ Q
QQM QQ

 

 
Thereinto, α is the gas volume fraction of in the dry
gas.
Carbon conversion η is the index to calculate how
much carbon is transferred to the content in gas during
the gasification process:
4
2
()22.4
100%
12
COCO CH
C
VVV
M

,
thereinto, V is gas volume, M is the amount of coal; and
C
is the amount of carbon in the coal.
Cold gas efficiency ηd is the heat value proportion of
fuel and gas products, the calculation formula are:
24
,
100%
HCOCH
df coal
hhh
h

,
thereinto, h is the gas heat value, ,
f
coal
h is the heat value
of coal.
3. Experimental Results and Discussions
In an actually running entrained flow gasified, the con-
trollable parameter is the feeding rate of coal and O2,
residence time and the amount of steam. Commonly,
gasification temperature and the atmosphere inside the
furnace can be adjusted by changing the rate of O/C. This
adjustment would change the processes of gasification
reactivity and the content of syngas, which would defi-
nitely change the residence time of gasification agent in
the furnace. Therefore, research of gasification tempera-
ture and residence time on the gasification characteristic
of coal has a significant meaning for the design and fol-
lowing operation of the gasified [4].
3.1. Effect of Temperature and Residence Time
on the Composition of Syngas
The method of changing injecting rate of N2 to change
Copyright © 2013 SciRes. EPE
T. LOU ET AL. 317
the residence time of pulverized coal staying in the fur-
nace was selected in this paper, the range is from 3s to
10s. Figure 2 shows the effect of gasification tempera-
ture and residence time on the composition of syngas [5].
123456789101
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7 CO2 CO CH4 H2
Gas Volume Fraction
Residence Times(S)
(a) Temperature:1450
123456789101
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7 CO2 CO CH4 H2
Gas Volume Fraction
Residence Times(S)
(b) Temperature:1350
123456789101
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7 CO2 CO CH4 H2
Gas Volume Fraction
Residence Times(S)
(c) Temperature:1250
112345678910
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
CO2 CO CH4 H2
Gas Volume Fracti on
Residence Times(S)
(d) Temperature:1150
Figure 2.The effectidence time on
e syngas
3.2. The Effect of Temperature and Residence
Figu of temperature and residence
of temperature and res
the components of synthesis gas of Datong Coal
As the figure shows that the composition of th
changes with residence time under different gasification
temperature conditions, the content of CO increases with
the increasing of residence time. When the temperature is
higher than 1300, the increasing rate becomes smaller
and the content of H2 slightly decreases with the increas-
ing of the residence time, while the content of CO2 gen-
erally remains steady. When the gasification temperature
is lower than 1300, the increasing rate of CO is rela-
tively bigger, and the fluctuation of H2 and CO2 is quite
drastic as well. The content of CO2 falls down with the
increase of residence time. With the increase of residence
time, the content of H2 would increase first and then de-
crease while the temperature is 1250. This is mainly
caused by the reactivity of H2O-C is higher than CO2-C.
As the residence time decreases to a certain extent, com-
bustion reactions are mainly happened in the furnace and
most of coal char would escape from the furnace directly
without reacting with H2O and CO2. So, most of H2 are
mainly produced by the paralysis of coal at this condition.
With the increase of residence time, the reacting time
between H2O-C and CO2-C would be extended corre-
spondingly. Followed by the large products of CO2 and
CO, the volume proportion of H2 in the syngas would be
decreased. Due to the reactivity of H2O-C is bigger than
CO2-C, the volume proportion of H2 in the syngas in-
creases again with the further increasing of residence
time. It can also be seen from the Figure that the volume
proportion of CH4 gets down gradually with the rise of
the temperature. When the temperature is above than
1350, the volume proportion of CH4 drops to 0, which
indicates that CH4 is mainly from the volatile compo-
nents, and the higher temperature of gasification reaction
is, the easier CH4 be decomposed [6,7].
Time on the Carbon Conversion and Cold
Gas Efficiency
re 3 shows the effect
time on carbon conversion and cold gas efficiency of
Datong coal. It can be seen from Figure that the carbon
conversion and cold gas efficiency increases with the
increase of residence time. When it is lower than 1350,
carbon conversion and cold gas efficiency increases with
the increasing of gasification temperature. When it is
higher than 1450, carbon conversion and cold gas effi-
ciency almost remains the same as that at 1350, even
slightly lower. The main reason is that the ash would be
appeared and accumulated on the surface of coal char
particles with the proceeding of gasification reactions,
when the gasification temperature is higher than the ash
fusion temperature, it would be transferred to liquid
phase. It tends to shrink as globular material on the surface
Copyright © 2013 SciRes. EPE
T. LOU ET AL.
Copyright © 2013 SciRes. EPE
318
Figure 3. Effect of Te mperature and Residence Time on the
ad to the decrease of effective surface area or separated
4. Conclusions
re is one of the most important fac-
to
me also has a great influence on ga-
si
temperature approaches to the coal ash
fu
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