Case Studies In TRIZ : FBC(Fluidized Bed Combustion) Boiler’s tube
erosion
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Case Studies In TRIZ :
FBC(Fluidized Bed Combustion) Boiler’s tube erosion
Jeong-Gil LEE / Project Leader in Utility Plant(LG Chem)
* Seung-Bae LEE / Innovation Support Team(LG Chem)
Jeong-mook OH / TRIZ Consultant in LG-PRC(ojmook@lge.com)
Department of Innovation Support , LG Chemical Ltd. Yeosu
plant
70-1, Hwachi-Dong, Yeosu-City, Chunranam-Do, Korea
E-mail: sbleej@lgchem.co.kr
TEL : 82-61-680-1075 FAX : 82-61-680-6005
Abstract
Our Utility Plant at Yeosu Plant have a FBC(Fluidized Bed
Combustion)Boiler.
The FBC Boiler, when used in a particular process
application, encounters the problem of tube erosion with coal.
By Improving tube erosion and changing its related material,
we perfectly solved the problem of FBC Boiler’s tube erosion and achieved the
maximum amount of operation days.
Introduction
In 1999, our LG Chem. Yeosu Plant adapted Six Sigma for
quality improvement in products, service, and processes which ultimately
improved customer satisfaction.
At that time, we also introduced the TRIZ activities (The
Theory of Inventive Problem Solving) in order to solve our company’s
technological problems.
So far, these innovation activities have consistently been
used in our many business fields.
In 2001, we presented our practice in Italy (The 5th IMC User
Group Meeting :『 Design a New Foam Separator
』) to demonstrate how we used TRIZ/Tech
Optimizer methodology to solve our problem.
Summary of Application of TRIZ
Initial Situation
In the FBC Boiler system, coal is fed into the furnace via
the Loop Seal .
Then the coal is combusted and flows into the Hot Cyclone.
Afterwards, this coal called , imperfect combusted coal , is
recycled again.
However, erosion is experienced by two factors ;
-
fluidized coal attack upon the surface of the tubes(due to
the air feeding)
-
fluidized coal fell down along the surface of tubes
So , we often experience unexpected shut-downs.
<Fig.1 Tube erosion point in FBC Boiler>
Function Modeling
We have done the function modeling to define our real problem
by considering various interactions between the tube, coal, and primary air.
<Fig. 2>
<Fig.2 Function Modeling>
Problem Definition
We feed the primary air to fluidize into the boiler , but
that caused the erosion.
This was the main problem we had to solve according to the
project.
Technical Contradiction
The technical contradiction here is ;
If the air speed is increased , this will increase the
combustion rate.
However, the erosion of the tube also increases.
When using the contradiction matrix, the following parameters
were used ;
<Fig.3 Contradiction Matrix>
The inventive principle can be transformed from contradiction
matrix is :
Mechanical Principle replacement : electricity or magnetic
field
Intermediary : To induce the medium between tube and
fluidized material
Preliminary action : To create preliminary conditions that
will prevent the object from harmful factors.
Operation Zone / Time Analysis
Physical Contraction
The physical contraction in this system is ;
<Air speed>has to be fast, because <to increase the
combustion rate>
<Air speed>has to be slow, because <to prevent tube erosion>
Separation Rule for space : increase the velocity of the air
in Furnace(UZ/T1)
but decrease the velocity of the air (HZ/T2).
Substance-Field Analysis
The Su-F model of the problem ;
The first recommendation by the standard solution set is
solved by the introduction of additives(S3) in the existing substance(S1).
And the second recommendation is solved by introducing the
foreign third substance or modified substance (S4) between them.
And the third recommendation is solved by introducing a
field(F1) which neutralizes the harmful effect.
Concept Generation
We generated several solutions by using TRIZ tool ;
|
Case 1.
It’s proposed to install the protective housing to
prevent tube from erosion.
<Sub-problem>
It’s anticipated secondary problems because of
material of housing and installation method. |
 |
|
Case 2.
It’s proposed to make the tube surface sticky in
order to have coals attached to the surface
<Sub-problem>
It’s hard to find high temperature(800-950degree)-
resistant adhesives. |
 |
|
Case 3.
It’s proposed to intake the air to prevent coals
falling down the tube surface
<Sub-problem>
It’s difficult to make air nozzle and the trouble of
installation. |
 |
|
Case 4.
It’s proposed to install preventive block to prevent
coals falling down the tube surface.
<Sub-Problem>
It’s anticipated the trouble of installation |
 |
|
Case 5. Application
It’s proposed to apply the abrasion-resistant
coating to prevent the tube erosion,
Ex> Mortar |
 |
Implementation
We investigated and attempted many cases to apply this
concept,
-
Choose and Test the coating material which was resistant to
erosion
:Coating material , range , height
-
Method (How to spray the coating material onto the tube)
-
Other property
As we referred above, we perfectly solved the problem of FBC
Boiler’s tube erosion and saved our failure cost.
| |
Past |
Present |
| Shutdown(period) |
157hr/yr |
no experience |
| Failure Cost |
$ 0.36million - |
|
Conclusion
Since 1999, we solved many problems and gained valuable
experience by using TRIZ and Six Sigma activity.
Especially, The creation of a new culture(TRIZ) is indeed
very beneficial.
The information collected from the different problem solving
tools is later on analyzed and used for other utility plants.
A series of technical concepts resulted from the various
results that were produced by the TRIZ application.
As we discussed above, by developing surface processing and
its related material, we perfectly solved the problem of FBC Boiler’s tube
erosion and developed the maximum amount of the operation days.
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