analysis of corrosion cause in the coal tar process equipments
DESCRIPTION
Analysis of Corrosion Cause in the Coal Tar Process EquipmentsTRANSCRIPT
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*1 1 2
1 2
Analysis of Corrosion Cause in the Coal Tar Process Equipments
Kuo-Ming Chen*1, Mei-Hui Wu1, Ming-Sheng Hsieh2
1 China Steel Corrosion Test Center, New Materials R & D Dept., China Steel Corp. 2 China Steel Chemical Corporation, Manufacturing Dept., Engineer
304
Abstract
In the coal tar distillation process , the light oil, naphthalene oil are extracted from coal tar
by high temperature distillation. But from the setup of the factory, it often be shutdown
resulting from corrosion of equipment and pipe, or plug of heat exchanger, and be a
troublesome for the production. The purpose of this paper is to analyze the root cause of
corrosion in the process, by means of field investigation, equipment failure analysis, analysis
of corrosion products on coupons surface, and the clogging materials in the equipments.
From the analysis results of equipments failure , corrosion products on the coupons surface
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and the clogging materials of equipments, it showed that the failure cause was the synergistic
effect of sulfide corrosion and cavitation or erosion. So, from the above results, we speculate
that the main cause of corrosion in the process of the coal tar factory was sulfide corrosion,
and in the effect of erosion and cavitation of coal tar, the iron sulfide layer was peeled off,
then the substrate was emerged, and reacted with sulfide to form the iron sulfide, like that
moved in circles to reduce the thickness of equipments. Separately, from the immersion test in
the coal tar at different temperature, it showed that the corrosion rate of 304 stainless steel
was very low, this result was contrary to the fact found in field, thus it can be seen the erosion
and cavitation played an important roles in the failure of the processing equipments.
Keywords: Coal tar, sulfide corrosion, pipeline corrosion, corrosion rate
1000(Coke)(Coke-Oven Gas)(Coal Tar)(1)
2
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3
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q
4
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5
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6
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C122 cavitation
S S
1.
2. 4. TWI Riskwise5. Richard B. Setterlund, P.E. Refinery Piping Fires Resulting from Variations in Chemical
Composition of Piping Materials , 2nd International Symposium On The Mechanical
Integrity Of Process Piping, 1996 Houston, U.S.A.
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P706
E-126
E116A/B
P121
C121
#41
CO
R121A/B/C
P122
C122
C123R123
P123
R-141E-102CH-141E-116
V-111AE-101E-141E-127
E-123E-122E-117
E-131
AFO
F-121
AFO
#22
P125A/B
T706
MV NO MNO
ACO
NFO
WFO
FP
NFO
NFO
NFO
#10
2. Fig. 2
The damage feature of circulating
pump.
1. Fig. 1 The Diagram of distillation process of Coal Tar.
CLO
CLO
CLO
8
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Fe7S8 C
9
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shrouds
1 2
: Fe1-xS
: FeS
: (Fe, Ni)9S8
: Fe1-xS
: FeS
: (Fe, Ni)9S8
!!!!!2 mm 4 mm
!0.029 mm 0.465 mm 1.867 mm 4 mm
10
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Fmnu Tqfdu/!Fmfnfou!!Bupnjd!Uzqf!!!!!&!!!!!!!&!!!!
P!!L!!!!!FE!!!!28/19!!!!47/4:!!Q!!L!!!!!FE!!!!!2/:1!!!!!3/1:!!T!!L!!!!!FE!!!!37/86!!!!39/56!!Gf!L!!!!!FE!!!!63/21!!!!42/92!!Oj!L!!!!!FE!!!!!3/29!!!!!2/37!!Upubm!!!!!!!!!211/11!!!211/11
A14 SEM/EDSFig. 14 SEM micrograph and EDS
analysis of coupon A14
A
B
C
A
B
C
A
B
C
A
B
C
20m
20m
A16 SEM/EDSFig. 15 SEM micrograph and EDS
analysis of coupon A16.
Fmnu Tqfdu/!Fmfnfou!!Bupnjd!Uzqf!!!!!&!!!!!!!&!!!!
P!!L!!!!!FE!!!!23/62!!!!3:/54!!Q!!L!!!!!FE!!!!!1/:8!!!!!2/29!!T!!L!!!!!FE!!!!33/27!!!!37/13!!Gf!L!!!!!FE!!!!75/46!!!!54/48!!Upubm!!!!!!!!!211/11!!!211/11
A20 SEM/EDSFig. 16 SEM micrograph and EDS
analysis of coupon A20.
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AB
C
AB
C
A
B
C
A
B
C
A
B
C
A21 SEM/EDSFig. 17 SEM micrograph and EDS
analysis of coupon A21.
023
016 016
014
A
B
C
023
016 016
014
A
B
C
A
B
C
A
B
C
18. SEM/EDSFig. 18 SEM micrograph and EDS
analysis of oxide layer of coupons cross
section.
Fmnu Tqfdu/!Fmfnfou!!Bupnjd!Uzqf!!!!!&!!!!!!!&!!!!
P!!L!!!!!FE!!!!!2/57!!!!!5/19!!T!!L!!!!!FE!!!!39/:3!!!!51/38!!Gf!L!!!!!FE!!!!7:/73!!!!66/77!!Upubm!!!!!!!!!211/11!!!211/11
Fmnu Tqfdu/!Fmfnfou!!Bupnjd!Uzqf!!!!!&!!!!!!!&!!!!
P!!L!!!!!FE!!!!!2/57!!!!!5/19!!T!!L!!!!!FE!!!!39/:3!!!!51/38!!Gf!L!!!!!FE!!!!7:/73!!!!66/77!!Upubm!!!!!!!!!211/11!!!211/11
SEM micrograph and EDS analysis of deposit of F121.
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11 11
1
1
11
1 Fe1-xS
11 11
1
1
11
1 Fe1-xS
Fmnu Tqfdu/!Fmfnfou!!Bupnjd!Uzqf!!!!!&!!!!!!!&!!!!
P!!L!!!!!FE!!!!!6/62!!!!25/42!!T!!L!!!!!FE!!!!39/15!!!!47/48!!Gf!L!!!!!FE!!!!73/61!!!!57/64!!Oj!L!!!!!FE!!!!!4/:6!!!!!3/91!!Upubm!!!!!!!!!211/11!!!211/11
Fmnu Tqfdu/!Fmfnfou!!Bupnjd!Uzqf!!!!!&!!!!!!!&!!!!
P!!L!!!!!FE!!!!!6/62!!!!25/42!!T!!L!!!!!FE!!!!39/15!!!!47/48!!Gf!L!!!!!FE!!!!73/61!!!!57/64!!Oj!L!!!!!FE!!!!!4/:6!!!!!3/91!!Upubm!!!!!!!!!211/11!!!211/11
Fig. 21 SEM micrograph and EDS
analysis of deposit of V1119.
2
2
11
1
1
11
22
1 Fe1-xS
2 C
2
2
11
1
1
11
22
1 Fe1-xS
2 C
Specimen
0
4
8
12
16
20
Cor
ros i
o nra
te( m
py)
File:CSCoil3.grf
1 2 3 4 5
Immersion test245 C, 7 day
1:SS4002:304 SS3:310 SS4:316L SS5:C-276
CSC coal tar
Imported coal tar
CSC coal tar + inhibitor
Imported coal tar + inhibitor
Specimen
0
4
8
12
16
20
Cor
ros i
o nra
te( m
py)
File:CSCoil3.grf
1 2 3 4 5
Immersion test245 C, 7 day
1:SS4002:304 SS3:310 SS4:316L SS5:C-276
CSC coal tar
Imported coal tar
CSC coal tar + inhibitor
Imported coal tar + inhibitor
Specimen
0
20
40
60
Cor
rosi
onra
te(m
py)
File:CSCoil5.grf
1 2 3 4 5
Immersion test300 C, 7 day
1:SS4002:304 SS3:310 SS4:316L SS5:C-276
CSC coal tar
Imported coal tar
CSC coal tar + inhibitor
Imported coal tar + inhibitor
Specimen
0
20
40
60
Cor
rosi
onra
te(m
py)
File:CSCoil5.grf
1 2 3 4 5
Immersion test300 C, 7 day
1:SS4002:304 SS3:310 SS4:316L SS5:C-276
CSC coal tar
Imported coal tar
CSC coal tar + inhibitor
Imported coal tar + inhibitor
13
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14