Analysis of Corrosion Cause in the Coal Tar Process Equipments

*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

*: [email protected]

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

1

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

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.

7

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

Fe7S8 C

9

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

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


analysis of coupon A16.


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



11

AB

C

AB

C

A

B

C

A

B

C

A

B

C



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.


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


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.

12

11 11

1

1

11

1 Fe1-xS

11 11

1

1

11

1 Fe1-xS


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


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


1:SS4002:304 SS3:310 SS4:316L SS5:C-276

CSC coal tar

Imported coal tar



Specimen

0

20

40

60

Cor

rosi

onra

te(m

py)

File:CSCoil5.grf

1 2 3 4 5


1:SS4002:304 SS3:310 SS4:316L SS5:C-276

CSC coal tar

Imported coal tar



Specimen

0

20

40

60

Cor

rosi

onra

te(m

py)

File:CSCoil5.grf

1 2 3 4 5


1:SS4002:304 SS3:310 SS4:316L SS5:C-276

CSC coal tar

Imported coal tar



13

Documents

Analysis of Corrosion Cause in the Coal Tar Process Equipments