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High Temperature Erosion of Dense Refractory Castables for CFBC Boilers
Article in InterCeram: International Ceramic Review · March 2017
DOI: 10.1007/bf03401198
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REFRACTORIES
019
1, V.G. Kadirvell1, L.N.Satapathy
3
K.
PrasadTemperature
R. Sanakaranarayana
High
Erosion2, of
Dense Refractory
Castables for CFBC
Boilers Temperature Erosion of Dense Refractory Castables
High
for CFBC Boilers
K. Prasad1, V.G. Kadirvell1, L.N.Satapathy2, R. Sanakaranarayana3
1
Bharat Heavy Electricals Ltd., Process and Captive Power Systems, Tiruchirappalli, Tamil Nadu (India)
2
Bharat Heavycirculating
Electricalsfluidized
Ltd., Ceramic
Technological
Institute,
Corporate
R&D, Bengaluru,
Karnataka
KEYWORDS:
bed combustor
(CFBC),
fluidization,
refractories,
bed material,
dense bricks, low cement castable, plastic ramming
mix,
erosion resistance
» Interceram 66 (2017) [1–2]
3
(India)
National Institute of Technology, Dept. of Metallurgical and Materials Engineering, Tiruchirappalli, Tamil
Nadu (India)
and systems, heat transfer nanofluids for close circuit cooling, selective
catalytic reduction catalysts for power plants, wear resistant ceramic
The corresponding author, K. Prasad, received his components, special refractories and high temperature characterization
Bachelor of Technology from A.C. College of Technol- of materials at Bharat Heavy Electricals Limited in Bangalore (India).
ogy, Guindy, Chennai, Tamilnadu (India) in the field of
Dr. S. Raman Sankaranarayanan obtained his Bachelor of Engiceramic technology in 2006. Since 2012 he has been neering (Metallurgical Engineering) from P.S.G. College of Technology,
working as Deputy Manager in the Process and Captive Coimbatore, Tamilnadu and his M.Sc. (Materials Engineering) and Ph.D.
Power Systems group of Bharat Heavy Electricals Ltd. (Materials Engineering) from Drexel University, Philadelphia (USA). He
(BHEL), Tiruchirappalli (India). Prior to this he worked has been with the National Institute of Technology, Tiruchirappalli, InThe corresponding author, K. Prasad, received his Bachelor of Technology from A.C. College of
in the Refractory Engineering Department of the Visakhapatnam Steel dia since 1998. His areas of interest are process metallurgy and quality
Technology, Guindy, Chennai, Tamilnadu (India) in the field of ceramic technology in 2006. Since 2012 he
Plant. Currently he is involved in the design engineering and analysis of management.
has been working as Deputy Manager in the Process and Captive Power Systems group of Bharat Heavy
refractory
lining and insulation for pulverized fuel fired boilers, circulatElectricals
Tiruchirappalli
Prior to
this generahe worked in the Refractory Engineering
ing
fluidizedLtd.
bed(BHEL),
combustion
boilers and (India).
heat recovery
steam
ABSTRACT
Department
of
the
Visakhapatnam
Steel
Plant.
Currently
he
is
involved in the design engineering and
tors. He provides field engineering support to resolve refractory problems
at various
powerlining
plantand
sites.
He is presently
pursuing
Master
of circulating
The erosion
resistance
of dense refractory bricks or castables used in
analysis
of refractory
insulation
for pulverized
fuelhis
fired
boilers,
fluidized
bed combustion
Science
in Metallurgical
andsteam
Materials
Engineering
Nationalfield
Institute
CFBCsupport
boilers tois resolve
tested asrefractory
per ASTM C 704. This method of testing deboilers and
heat recovery
generators.
He at
provides
engineering
of
Technology
(NIT), Tiruchirappalli,
Tamilnadu
(India) inpursuing
the field his
of retermines
the relative
erosion of
a refractory at room temperature only.
problems
at various
power plant sites.
He is presently
Master
of Science
in Metallurgical
and
fractories
for
CFBC
boilers.
E-Mail:
kprasad@bheltry.co.in
Hence,
solid
particle
erosion
at
elevated
temperatures is desired in seMaterials Engineering at National Institute of Technology (NIT), Tiruchirappalli, Tamilnadu (India) in the field
V.G. Kadirvell received his Master of Technology (Energy Engineer- lecting the suitable refractory quality for boiler applications. The dense
of refractories for CFBC boilers. E-Mail: kprasad@bheltry.co.in
ing) from the National Institute of Technology, Tiruchirappalli (Formerly refractory materials for CFBC boilers are usually eroded at operating
known as Regional Engineering College, Tiruchirappalli). He has more temperature (~900 °C) by hot circulating solids at high temperatures.
V.G. 25
Kadirvell
Technology
(Energyinsulation
Engineering)
fromwork,
the low
National
Institute
of
than
years of received
experiencehisinMaster
design of
engineering
of lining,
In this
cement
castable–45,
low cement castable–80 and an
Technology,
Tiruchirappalli
(Formerly
known
as
Regional
Engineering
College,
Tiruchirappalli).
He
has
more
and refractory for pulverized fuel fired boilers, circulating fluidized bed 80 % alumina-based plastic refractory castable, three varieties of dense
combustion
boilers
and heat inrecovery
generators.
He isinsulation
currentlyand refractory
castables
usedfuel
in CFBC
than 25 years
of experience
design steam
engineering
of lining,
refractory for
pulverized
fired boilers, were selected for testing of
working
as Senior Deputy
General
Manager (SDGM)
Heavy steam
erosiongenerators.
properties.He
Theiserosion
tests were conducted at room temperaboilers, circulating
fluidized
bed combustion
boilerswith
and Bharat
heat recovery
currently
Electricals
Ltd Senior
(BHEL), Tiruchirappalli,
(India).
andElectricals
boiler operating
temperature of 900 °C at three different anworking as
Deputy General
Manager (SDGM) with Bharat ture
Heavy
Ltd (BHEL),
Dr. Lakshmi Narayan Satapathy obtained his post-graduate de- gles of impingement (30°, 45° and 90°) using specially developed high
Tiruchirappalli (India).
grees in chemistry, materials science, ecology and environment and temperature erosion test equipment following the ISO 16349 (2015)
management, prior to his Ph.D. in Materials Engineering from the Indian standard. The erosion loss result values (in cm3) were compared, and
Dr. Lakshmi Narayan Satapathy obtained his post-graduate degrees in chemistry, materials science,
Institute
of Science, Bangalore. He has more than 25 years of R&D ex- this comparison is useful in selection of suitable material for various
ecology and
environment ceramics,
and management,
to his Ph.D.
in Materials
Engineering
from
the boiler.
Indian
erosion
prone zones
of the
perience
in alumina-based
microwaveprior
processing
of materials
AUTHOR
Institute of Science, Bangalore. He has more than 25 years of R&D experience in alumina-based ceramics,
1. Introduction
Circulating fluid bed combustors (CFBCs) are steam generating boilers
that use fuels like lignite, pet coke and solid wastes. The operation of
CFBC boilers involves the circulation of hot, high-velocity solids containing a mixture of refractory bed material and fuel at temperatures around
900 °C. Fuel is burnt in the vertical combustion chamber furnace in
fluidized condition at a temperature around 900 °C in a reducing atmosphere with slight positive pressure. The mixture of bed material and fuel
is fluidized by preheated primary air introduced through air nozzles at
the bottom of the combustor bed, and by the flue gas generated during
combustion. The air (primary and secondary) and gas flow upwards with
a relatively high velocity, filling the entire combustor with suspended
solids. The combustion gas entrains a considerable portion of the solids
in the combustor and carries them over to the recycling cyclone where
the entrained bed materials are separated from the gas. The bed material
separated by the recycling cyclone is collected in the fluidized seal pots
and is then returned directly into the furnace's lower part at higher pressure through the return leg of the seal pot.
The refractory forms an integral part of several of these components
1 Bharat Heavy Electricals Ltd. Process and Captive Power Systems, Tiruchirappalli, Tamil
Nadu (India)
2 Bharat Heavy Electricals Ltd., Ceramic Technological Institute, Corporate R & D, Bengaluru,
Karnataka (India)
3 National Institute of Technology, Dept. of Metallurgical and Materials Engineering
Tiruchirappalli, Tamil Nadu (India)
01–02|17
020
Table 1 · Properties of dense refractories used in CFBC applications
Low cement castable–45:
LCC–45
Low cement castable–80:
LCC–80
Alumina plastic mix
(80 %) : 80(P)
-
1550
1500
1650
Al2O3 / mass-%
Fireclay
Bauxite
Bauxite
46.0 min
80.5 min
82.0 min
Fe2O3 / mass-%
1.0 max
0.72 max
1.3 max
CaO / mass-%
3.0 max
0.9 max
-
P2O5 / mass-%
-
-
4.5 max
Bulk density / g/cm3
110 °C
2.30 min
2.5 min
2.75 min
Cold crushing
strength / N/mm2
110 °C
1200 °C
110 min
90 min
76 min
45 min
60 min
Thermal conductivity
/ W/mK
500 °C
1.10 max
1.65 max
-
1000 °C
1.15 max
1.60 max
-
-
Minimal vibration / rodding
Minimal vibration / rodding
Pneumatic Ramming
Property
Max. service
temperature / °C
Raw material base
Chemical analysis
Application
like the combustor, the inlet duct connecting the combustor and the
cyclone, the cyclone, the seal pot and ducts connecting the seal pot
and the combustor. The components are lined with a dense refractory
comprised of brick shapes made from fireclay and andalusite and low
cement castable containing 45–80 % of alumina and backup insulation comprised of shaped insulation bricks, calcium silicate blocks and
a vermiculite / pearlite / grog-based insulation castable depending on
the operating condition inside. The dense refractory bricks and castable
lining take care of the erosive environment generated due to the hot
circulating bed's solids at higher velocities and at high temperatures.
Hence, among various properties for dense refractory like bulk density,
porosity, thermal shock resistance, thermal conductivity, CO resistance
etc., erosion resistance has a major role in selecting the suitable grade of
dense brick or castable quality.
The various challenges that are thrown at the refractory in a CFBC boiler
have been well documented [1–5]. The demands of quantity and quality of refractories that were used in industrial boiler technologies have
been low. However in CFBC technology, the design of boilers involve the
usage of high quality and quantities of refractory [2]. With a target of
reducing refractory material in the boiler and increasing heat transfer
areas by introducing steam cooled walls, CFBC technology has evolved
from external hot cyclone technology, involving layers of refractories at
temperatures around 900–950 °C to internal steam cooled cyclone technology operating at around 450–550 °C with a single erosion protection
layer of the refractory, as mentioned in the literature [6, 7]. In both cases, the dense refractory used must possess adequate abrasion resistance
to withstand the high velocity circulating solids of up to 6 mm in size and
hot gases. Moreover, with the transition of refractory material technology from multi-layered brick design to double-layered castable design the
current CFBC technology has also adapted well to the market conditions.
In a CFBC boiler, the risk of refractory failure to erosion of dense refractories by solid particles travelling at high speeds at elevated temperatures is a serious threat to the lifetime of the equipment. A failure
in refractory due to poor erosion resistance also disrupts continuous operation of the boiler, thereby leading to interruption of the power gen-
eration. The cause of erosion wear of the refractory surface may include
both physical erosion by solid particles and chemical corrosion due to
fuel quality / hot gas / slags and physical wear due to particles circulating at high velocity at high temperatures [8]. There is a requirement in
understanding the erosion rate of refractory castable at elevated boiler
operating temperatures of dense refractories used in abrasive environments like that of the cyclone inlet duct's sidewalls and roof. Although a
number of studies [9, 10, 11] are available on the solid particle erosion
of metals and ceramics at elevated temperatures, very little work on erosion resistance of refractories can be found in the literature.
Bakker et al. studied the erosion resistance of refractory materials
used in CFBC boilers with respect to the effect of the bed material that
is circulated inside a circulating fluidized bed combustor [12]. The selection of refractory for water cooled cyclones based on erosion testing of
various refractory bricks and castables has also been studied elsewhere
[6]. For hot cyclone technology of CFBCs, the high temperature erosion
behaviour of refractory brick materials comprised of coarse and fine aggregates have been studied [8]. There is also a study done on the hot erosion behaviour of alumina-based low cement castables and phosphate
bonded plastic refractories for FCCU applications in petrochemical industry [13]. Information in the literature on the hot erosion test results for
dense castable varieties used in CFB applications is scarce. This paper refers only to the physical erosion of dense refractory castables commonly
used in CFBC boilers with hot cyclone technology in erosion prone areas
like the cyclone inlet ducts' long and short walls and its inlet duct roof.
In CFBCs, there is an increasing trend to use dense monolithic castables
for their ease of application and improved application techniques by saving the boiler's down time. However, the inherent problem of calcium
aluminate cement (CAC)-bonded refractories is that they attain better
density and better high temperature properties including high erosion
resistance at temperatures above 1200 °C, due to mullite formation
[14, 15]. In a CFBC boiler, the operating temperatures are well below
900–950 °C. Hence, this work involves the study of the erosion properties of samples of commonly used refractory castables like low cement
castable–45, low cement castable–80 and 80 % alumina plastic mix us-
REFRACTORIES
ing a high temperature erosion tester at a boiler operating temperature
of 900 °C.
A comparison of the erosion behaviour of the various samples has been
carried out at two different temperatures viz., 27 °C (ambient temperature) and boiler operating temperature 900 °C. The selection of impingement angles for testing is pivotal in getting more meaningful results.
Although the existing test standards for testing erosion resistance for refractories are the involves impact of the erodent at a 90° angle in highly
erosive zones of boilers like cyclone inlet ducts, cyclone target walls, roof
etc., the tangential or low angle impact by solids flowing through causes
erosion of refractories. The importance the low angle of impact of solids
inside a cyclone of CFBC boilers has also been emphasized in the literature [6]. Based on these, in this study angles of 30° and 45° were chosen
for erodent impingement and a 90° impact angle along with existing
room temperature testing for erosion resistance of refractories using the
ASTM C704 [16] test method.
2. Materials and testing
021
1
Fig. 1 • Erosion tester used for measuring the erosion resistance of refractory test
pieces at elevated temperature
High temperature erosion tests were carried out on refractory samples
of low cement castable–45, low cement castable–80 and 80 % alumina plastic refractory mix, which were sourced from an Indian refractory
2
(a)
(b)
supplier for boilers. The material data sheets of these samples are listed
in Table 1. The sizes of the test samples were 100 mm x 100 mm x 25 mm.
The samples were casted in moulds using a castable mix. These samples were then air cured for 24 h, preheated to 110 °C for 24 h and then
prefired to 900 °C for 3 h before being subjected to tests. They were then
tested using the “high temperature erosion tester” facility developed in
tester house
is used
measuring
the erosion
resistance
at the for
Ceramic
Technological Institute
located at Bharat
Heavy of refractory test pieces at elevated
Electricals
Limited –ofBengaluru
Division
in accordance
with the regulating
ISO
, and mainly
consists
blasting
devices,
a pressure
chamber, a sample chamber and
16349 (2015) standard.
erosion tester
is used1.
forThe
measuring
erosion resistance
of re- in the sample chamber with the square
nents, asThe
depicted
in Fig.
testthe
sample
was placed
fractory test pieces at elevated temperature, and mainly consists of
mm x 100blasting
mm devices,
perpendicular
(at a chamber,
90° angle)
orchamber
at lowand
angles of 30° or 45° to the protective tube.
a pressure regulating
a sample
components,
depicted
in Fig. 1. The
test sample wasto
placed
ature wasother
raised
fromas the
ambient
temperature
900in °C at a rate of 5–8 K/min. The material
the sample chamber with the square face of 100 mm x 100 mm perpen(at a 90°
or at low angles
of 30° or 45° toThen
the protective
held fordicular
30 min
at angle)
the testing
temperature.
the abrasive media of 1000 g ± 5 g of black
tube. The temperature was raised from the ambient temperature to 900 °C Fig. 2 • 2a) Samples of refractory castables before testing, 2b) Samples of refracde grainsat of
particle
sizeThe
300–850
μm was
washeldimpinged
theafter
charging
funnel of a suitable
tory castables
testing
a rate
of 5–8 K/min.
material sample
for 30 min atthrough
the testing temperature. Then the abrasive media of 1000 g ± 5 g of
n 900 ± 10
at 16
kPa
pressure
inside
theμmsample
chamber. After completion of the test, the
blackssilicon
carbide
grains
of particle size
300–850
was impinged
immersion method.dust
Photographs
samples
before
through
the test
charging
funnelwas
of a suitable
orifice from
within 900
10 s at wateraccumulated
cooled and
the
piece
removed
the± chamber,
blownof off
and
thesubjection to
16 kPa pressure inside the sample chamber. After completion of the test, the erosion test and after erosion testing are shown in Figs. 2a and 2b,
respectively
the furnace wasin
cooled
and the
test piece was removed
the cham- room
Similarly,
temperature testing for the sample
oss was measured
cubic
centimetres
(cm3).from
ber, accumulated dust blown off and the volumetric loss was measured
° angle impingement
raisingtesting
the for
temperature
inside the testing chamber. The
Similarly,without
room temperature
the
in cubic centimetreswas
(cm3). done
sample at 90° or 30° angle impingement was done without raising the 3. Results and discussion
rosion loss
(ΔV) of material by erosion from each of the test samples was calculated using the
temperature inside the testing chamber. The volumetric erosion loss Three types of castable are extensively used in the various components
uation: (ΔV) of material by erosion from each of the test samples was calculated of a CFBC boiler. They are alumina-based dense varieties, wherein the
alumina mass-% varies in each variety, as demonstrated in Table 1 where
using the formula in Equation (1)
the material properties are shown. As can be seen in the table LCC–45
contains 45 mass-% Al2O3, LCC–80 contains 80 mass-% Al2O3 and 80(P)
(1)

ΔV =
(1)
is
a plastic ramming mass that contains up to 82 mass-% Al2O3.

Figure 3 shows the erosion loss (in cm3) plotted against three different angles of impingements 30°, 45° and 90°. Both LCC–45 and LCC–80
Where, ΔV is the volumetric3 loss (in cm3) of material, M1 ( in g) and showed excellent erosion resistance at a boiler operating temperature
of mass
material,
M1 (in
g) and
and
(in °Cg)irrespective
are theofinitial
and
final mass
of the plass the volumetric
loss
M2 ( in g) are
the (in
initialcm
and )final
of the samples
tested
BD M2
of 900
the angle
of impingement.
However,
3
densities
and the(in
ap- g/cm
is the bulk
of thebulk
sample
(in g/cm3).ofBulk
tic castable
showed
high erosionand
valuesthe
at three
different angles of im). Bulk
densities
apparent
tested and
BDdensity
is the
density
the
sample
parent porosity of the samples were measured using the Archimedes pingement at a testing temperature of 900 °C. The test results showed
he samples were measured using the Archimedes water immersion method.Images of samples
ction to the erosion test and after erosion testing are shown in Fig. 2.
01–02|17
022
3
Fig. 3 • Erosion loss (in cm3) of the dense refractory castable with an impact angle
at 900 °C
the vulnerability of plastic refractory castables to highly abrasive environments at elevated temperature.
It was noted from the extensive experiments that erosion resistance of
castables does not show an increasing trend with respect to an increase
in temperature. The reason is the operating temperatures to which these
castable are subjected; mullite formation is not accentuated, which
helps attain adequate thermal strength values [14, 15]. Among the three
varieties, 80(P) exhibits poor erosion resistance compared to other two.
The erosion values of refractory castables LCC–45 and LCC–80 are lower and are similar. The erosion value of plastic castable–80(P) is higher
and is more than that of the LCC–45 and LCC–80 castable materials. The
impact angle of 45° causes marginally lower erosion compared to angles
of 30° and 90°. It was found from the experiments that the variation in
erosion loss values from low to high impact angles provided no significant change for all three castables at elevated temperatures.
Figure 4 shows the erosion resistance of various castable as a function
of the impingement angle at room temperature. The erosion loss values are dependent on the impingement angles. The values of 80(P) and
LCC–80 have a substantial increase in erosion rates at 90° impingement
angles, as compared to the behaviour of the LCC–45 castable. Refractories are brittle in nature at room temperature. The impingement of
erosive material at 90° caused more damage to the samples compared
to the tangential impingement of 30°. The erosion behaviour is similar
to the results obtained for various alumina bricks [8]. Under the given
testing conditions, LCC–80 has the lowest erosion rate at room temperature at an impingement angle of 90°. The erosion loss of 80(P) at 30° is
the lowest among the three varieties but it also shows high erosion loss
at impact angle of 90°. With the room temperature tests, plastic castable
80(P) has the better erosion resistance.
In Fig. 5, the existing method of erosion resistance testing of refractories ASTM C704 were also conducted to compare results with the testing
method discussed in this paper at room temperature. The values of 90°
impingement at room temperature for the prefired samples as per ASTM
C704 [16] are similar and comparable to those of the 90° testing at room
temperature using the high temperature test rig. From the results, it was
found that the erosion loss (in cm3) of low cement castable varieties are
low compared [5]. Although low cement castable–80 has a higher alumina content as mentioned in [5], low cement castables with a higher
alumina content do not always have lower erosion loss. Also, the plastic
refractory 80(P) is phosphate bonded and has low erosion loss values
4
Fig. 4 • Erosion loss (in cm3) of the dense refractory castable with an impact angle
at room temperature
5
Fig. 5 • Comparison of erosion loss values between ASTM, C704 and IS 16349
[17] as tested by ASTM C704 [16]. The erosion resistance of plastic refractory 80(P) using ASTM C704 gives a superlative result, but from Fig. 3 it is
quite obvious that at an elevated temperature of 900 °C, the material has
very poor erosion. Hence, the ASTM C704 test method will not provide
realistic erosion loss data for plastic 80(P).
Figure 6 shows the erosion loss of three products as measured by erosion loss (in cm3) using SiC erodent. These test results show that all three
major classes of refractories used in CFBC boilers have been tested for
erosion resistance at room as well as boiler operating temperature at
various angles of impingement. Unlike bricks that are fired during manufacture, castables are unfired and tend to become eroded quickly. This
may be attributed to the fact that mullite formation increases rapidly
at 990 °C and this cannot be achieved at boiler operating temperatures.
Mullite formed products like bricks have better erosion properties. A
study on aluminosilicates and high temperature erosion resistance for
prefired products has already been undertaken [8]. At elevated temperature (boiler operating temperature), low cement castable LCC–80 has
better erosion resistance followed by low cement castable–45 and then
the plastic refractory castable.
To understand the microstructure of the three alumina-based castables
selected, SEM observations were carried out on the polished surfaces.
REFRACTORIES
023
8
6
(a)
(b)
Fig. 6 • Erosion loss of dense castables – a comparison
7
(a)
Fig. 8 • 8a) Erosion photo of LCC–80 at 900 °C enlarged, 8b) Erosion photo of 80(P)
at 900 °C enlarged
(b)
(c)
Fig. 7 • 7a) SEM image of eroded surface of LCC–45 at 900 °C at 90° impingement
angle, 7b) SEM image of eroded surface of LCC–80 at 900 °C at 90° impingement
angle, 7c) SEM image of eroded surface of 80(P) at 900 °C at 90° impingement
angle
The images of the three samples tested at 900 °C at a 90° angle of impingement are shown in Fig. 7a, 7b and 7c for LCC–45, LCC–80 and 80(P),
respectively. The erosion in all three samples had a similar pattern. The
weak, porous binder phase first undergoes dislodgement and thus further causes loosening and then exposure of aggregates of alumina to
impact erodent material.
The brittle erosion mechanism is clearly evident on the SEM photographs of the three materials tested. In Fig. 8a of the LCC–80 900 °C
testing, the aggregates have cracked. The cracks further cause pulling
or breakage of grains due to the impact of erodent materials. LCC–80,
which has the better erosion resistance, has lower binder materials and
strong aggregates, as shown in Fig. 8a. The poor erosion resistance values of 80(P) are justified by the presence of more binder pull out and a
greater extent of damage to the aggregates, as shown in Fig. 8b.
4. Conclusions
From test results we can see the following:
1. The room temperature ambient erosion tests are sufficient for LCC–45
and LCC–80 castables.
2. In the case of plastic refractories, the room temperature and 900 °C
operating temperature test results vary greatly. Hence, it is proposed
to conduct high temperature erosion testing in the case of plastic refractories and rammables.
3. The ASTM C704 test method will not provide realistic erosion loss data
for plastic 80(P). During ASTM C704 testing, plastic shows a very good
erosion resistance value but on testing at elevated temperature they
show very high erosion loss when compared to LCC–45 and LCC–80.
Also, during room temperature testing at various angles the behaviour
of the plastic is similar to LCC–45 or LCC–80 but in real time high tem-
01–02|17
024
perature testing they have the greatest loss.
4. Although low angle impingement results are more relevant to the operating conditions prevalent inside the boiler but the results indicate
that the erosion loss difference between low and high angles are not
much for the three different samples tested.
5. LCC–80 possess adequate erosion resistance compared to the other
two castables and hence can continue to be used in highly erosive
zones of cyclone inlet ducts.
Acknowledgment
The authors are grateful for the encouragement, support, guidance
and facilities extended for the research by Bharat Heavy Electricals Ltd
(BHEL), Tiruchirappalli, India, The Ceramic Technological Institute (CTI),
Bharat Heavy Electricals Ltd (BHEL), Bengaluru India and the National
Institute of Technology (NIT), Tiruchirappalli, India.
References
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and maintenance issues of CFBC boilers. Appl. Therm. Eng. 102 (2016) 672–694
[2] Snyder, G.E.D., Ehrlich, S.: Refractories in CFB applications. Proc. 12th Int. Conf. Fluidised Bed Combustion, 09.05.–13.05.1993, ASME 2 (1993) 967–982
[3] Crowley, M.S., Bakker, W.T., Stalling, J.: Refractory applications in circulating fluid
bed combustors. Proc. 11th Int. Conf. Fluidised Bed Combustion, ASME (1991) 417–423
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Received: 05.11.2016