Yin R. Metallurgical Process Engineering
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108 Metallurgical Process Engineering
Continues Table 4.1
Refining function Hot metal pretreatment BOF Secondary refining
Decarburization
©
0(
8
--------------~
8 (*)
Heating-up
8
..
©
Degassing
©
..
8
Inclusion modification
0
..
8
Deoxidation
o
»
8
Alloying
©
»
8
Purification
8
0(
© »
8
. . . .
8 Main procedure for realizing the function; © Next important procedure for realizing the function;
o Degenerated function in this procedure; (*) For IF steel, vacuum decarburization is more important.
Attention should be paid to the collections of procedure's functions. They
should be divided at least into the set
of
functions
of
unit procedure and the set
of
procedures, functions
of
process system (or
of
process section). The functions
of
BOF steelmaking have given above as an example
of
collection
of
functions
of
unit procedure. However, the set
of
procedures' functions
of
process system is
acquired by analysis-integration
of
process. The way to do it involves the analysis
on many procedures
of
different functions firstly, and then the selection, distribu-
tion or replacement
of
realizing mode and a share
of
one or more functions in
different procedures are arranged. Finally, the collection
of
procedures' functions
of
system through analysis-optimization under the guidance
of
the principle
of
dynamic programming entirely is formed. For example, the sulfur removal can be
proceeded in such procedures as ore sintering, blast furnace (BF), hot metal pre-
treatment, basic oxygen furnace (BOF), electric arc furnace (EAF), secondary
metallurgy etc. But through the technical comparison and economic evaluation all
the oxidation procedures (BOF, EAF, etc.) should not be used for desulfurization,
while the procedures as hot metal pretreatment, blast furnace, ore sintering. can
remove sulfur reasonably. However, the special desulfurization treatment should
be done in secondary metallurgy for control
of
the shape and property
of
sulfide
inclusions in steel. That is the significance and the value
of
the analysis-
optimization for the set
of
procedure's functions
of
process system.
The set of functions of unit procedure is referred to conversion, transformation,
transport and storage
of
materials and energy charged on this one procedure, and the
special behavior and action required in realization
of
the given targets of it. However,
the optimized matching and the reasonable linkage with other procedures should be
also considered. While let the reasonable matching and linkage of various state pa-
rameters
of
the conversion, transformation, transport and storage
of
materials and
energy among units in the process being clear more effectively, the coordination of
time-sequence factors and a correctspace layoutmust be solved simultaneously.
If the set
of
procedure's functions in the steel manufacturing process is ex-
Chapter 4 Analysis and Integration
of
Manufacturing Process
of
Metallurgy 109
pressed by F, while a function
of
a certain unit procedure in the process system is
expressed by f
ij,
then an expression is obtained as follows :
F=
{J
ij}
where F is the set
of
procedure's functions in the manufacturing process system;
fij is the function "i" possessed by certain procedure ''j''; i is or the number
of
function, i=l,'··
,m;j
is the number
of
unit procedure.j'<l.
:->
, n.
So, the anyone set
of
procedure's functions
{fij
} can be expressedto form with equal
dimensionsmathematically. If one procedure doesn't possess one certain or more func-
tions, then this functioncan be representedin matrix with o.Therefore, the set
of
proce-
dure's functions
of
systemF in the steelmanufactwing processcan be expressed as
I;!
1;
2 I;n
F =1fij1= ' : f
22
f 2n
r:
i:
i:
One certain or more functions were distributed in several procedures
of
process
system, the optimum
of
such distribution would be characterized by such basic
parameters running through whole process as the matter quantity index (includes
mass, flux, concentration), temperature and time as:
fij=
f(W(I:W
k),T(I: T
k),
g(t))
Cf,ij=
f'
(W(I: wk),T(I: T
k),
get))
where, F is the set
of
procedure's functions in the process system; fijis the func-
tion "i" possessed by certain procedure '
'j''
;
CJ:ij
is the distributive share
(O
~
1)
of
the function "i " in the procedure '
'j''
; i is the function number
;j
is the number
of
unit procedure in the manufacturing process; W is the matter quantity index (in-
cludes mass, flux, concentration, etc.); Wk is the relevant factors influenced on
matter quantity index; T is the temperature
of
the flow
of
metals in the process; T,
is the relevant factors influenced on temperature
of
metals; g(t) is the time-
characteristic parameters and their expression form.
4.4.3 Coordination-optimization
for
the set
of
procedures' rela-
tions in steel manufacturingprocess
The collection
of
relations among procedures in the steel manufacturing process
should consider not only the linkage and matching
of
time-sequence factor, space-
location factor, energy-temperature factor, property-feature factor, as well as
of
func-
tions and equipment capacities (tonnage)
of
procedures (include neighboring and dis-
tant), but also the rationality
of
transportation ways (the transport facilities, transport
status, and the layout
of
transport routes). That means the "minimization"
of
attenua-
tion
of
mass flow
of
metals,
of
temperature undulation
of
the mass flow,
of
waste
emission in process, of processing time and
of
manufacture inventory; as well as the
110 Metallurgical Process Engineering
product quality and performance satisfying to use. It would be realized by coordina-
tion-optimizationfor the set
of
procedures' relations.
Sometimes, one certain procedure(e.g. continuous casting) plays the keynote
role in the evolution
of
the manufacturing process, after which the neighboring
procedures can develop forward then. The practices from 1970 s had proved that
replacement
of
ingot
teeming-blooming
procedure by continuous casting proce-
dure in the steel manufacturing process
ofBF
-BOF
route had promoted the evo-
lution
of
the collection
of
relations among the procedures in whole production
process. However, as the pursuits in continuation, compactness, rhythm and syn-
ergy were brought about, the connotation
of
the set
of
the procedures' relations
was more and more abundant. Contents on this aspect will be further discussed in
the Chapter 7 "Operating dynamics in the production process
of
steel plant".
Analysis-optimization
of
the set
of
procedures' functions is the basis
of
coordi-
nation-optimization
of
the set
of
procedures' relations. From viewpoint
of
station-
ary, procedure's functions can be summed up into "capacity" function (e.g. output,
productivity, transport power, etc.) and "intensity" function (e.g. quality, property
of
products and semi-products). Therefore, the relationships among procedures
are always summarized as the connection and linkage
of
"capacity" and matching
of
"intensity". The relevant procedures in the steel manufacturing process should
take the relations
of
time-sequence characteristics during dynamic operation (as
the layout was fixed, so the space-location relations were relatively fixed as well).
A series
of
relationships in short range or long range and relations among proce-
dures may be established through analysis-optimization
of
the set
of
the proce-
dure's functions and coordination-optimization
of
the set
of
procedures' relations.
These linkage-matching relations include aspects like the matter amount, mass
flux, concentration, temperature, energy, time, space, metal structure, property,
quality, etc.
It
is a series
of
"generalized loop engineering" (buffer engineering)
practically, whose reliability and flexibility may be presented for appraisal in its
entirety
of
manufacturing process. Generally, abatement
of
the buffer value is the
developing trend. For example, under the condition
of
normal production and
operation, the buffer value
of
process route: blast
furnace-mixer-open
hearth-
teeming-ingot
storage-soaking
pit-blooming-intermediate
billet
stocking-
reheating-hot
rolling mill is very large. On the other hand, the buffer value
of
the route: blast furnace - torpedo - hot metal pretreatment- converter -
secondary
metallurgy-thin
slab
casting-strip
rolling is obviously smaller. The
technological significance and economical value are self-evident.
The relationships among various procedures in manufacturing process may be
characterized by the mathematical concept
of
"set".
Let X represents the set
of
procedures Xi in the BF-BOF process steel plant. The
relationships involve relations
of
"capacity", "intensity" and "time-characteristic",
meanwhile, these relations even include the collection
of
engineering relation-
Chapter 4 Analysis and Integration
of
Manufacturing Process
of
Metallurgy 111
ships as heredity, variation, pregnancy (especially at long range) among proce-
dures and transportation in process system at the same time. According to system
theory,
if
one procedure X;E X has interacted with the other procedure X
o
E X
of
the system, the interaction relationship is expressed by r, then:
X;rX;" X
orX
;
or X
o=r(X;),
X,=r(X
o)
where X is the set
of
procedures in the process; i, 0 is index number
of
proce-
dure;
r is the interaction relationship among procedures.
In fact, the process running is supported by the mutual coordination
of
various
generalized buffer among unit procedures, so the set
of
procedures' relations must
contain the generalized buffer relations among processing procedures. Its expres-
sion is the relationships
of
collection
of
buffers among the procedures.
As the production process system
of
different types
of
BF-BOF steel plants is
the integration
of
much more procedures with specific relationships among each
other, and then the set
of
procedures' relations in whole process system has the
expression formula as follows:
R= {r 1 r= (X;,xo) } i,o= l,
...
,n
where
R is the set
of
procedures' relations; r is the interaction relationship
among procedures;
i.o is index number
of
procedure, l,
...
,n.
If
the above-mentioned set
of
procedures' relationsare expressed by matrix, then:
r
l l
'12
'in
R =1'ij
1=
r
21
r
22
r
2n
:
r
nl
r
n2
r;
The set
of
unit procedures' relations are mainly embodied with the collection
of
relations among neighboring procedures, sometimes those
of
longer range, then:
R
={r
ijl
;
~I
~
m
,
j~l
~
n}
As the connotation and formulation
of
unit procedures' relations are very complicated,
it seems that it is convenient for description
of
the set
of
unit procedures' relations with
the basicparameters
(w, T,and t)
of
the steelmanufacturing process, then:
rij =qJ(W(Iw
k),T(IT
k),g(t))
4.4.4 Reconstruction-optimization
of
set
of
procedures in steel
manufacturing process
Inthe past 150 years, the tech-progresses
of
the steel industry can be summed up
to the following indications:
1. A series
of
new
technologies and facilities developed with innovation, such
as
oxygen
converter, continuous caster, hot metal pretreatment,
secondary
refining, controlled rolling and controlled cooling (TMCP), thinslab casting-
112
Metallurgical Process Engineering
rolIing, strip casting, ore direct reduction, smelting reduction and so on.
2. A series
of
technologies and facilities were improved in the evolution, such as
ultra-large blast furnace, UHP-EAF, large sintering machine, tandem hot rolling
mill, seamless tube mill and so on.
3. A series
of
technologies and facilities disappeared and were replaced in the
couse
of
competition, such as ore sintering pot, air blown converter, open hearth,
hot metal mixer, ingot casting, blooming mill, three-high reversing mill, pack-
rolling mill, small electric arc furnace with reduction period, and so on.
The above mentioned tech-progresses affected the structure
of
the steel manu-
facturing process and embodied the thought on the analysis-optimization
of
the
set
of
procedure's functions, the coordination-optimization
of
set
of
procedures'
relations, and consequently the reconstruction-optimization
of
set
of
procedures.
Ingeneral, the basic parameters
of
the steel manufacturing process are converged
into the optimum critical-value gradualIy, that results some technologies to be
eliminated from production line or some functions to be replaced. FinalIy, the
structure change entirely
of
the steel manufacturing process is brought about, i.e.
the restructuring-optimization
of
set
of
procedures has arisen.
Reconstruction-optimization
of
procedures in the steel manufacturing process
may be characterized by mathematical concept
of
set also. Presuming process
system X is colIected with some recognizable and independent procedures Xi with
special functions, then:
X =
{XjEX
I
i
~
hn
}
Due to process system consists
of
the procedures
of
"rigid component" and
"flexible component", so it could be expressed as,
X =
{(X
Fb
X
Ri
) [
XFlEX, XRiEX }
The above discussions on the set
of
procedure's functions, the set
of
proce-
dures' relations and the set
of
processing procedures intend to get statement
of
physical-mathematical model
of
system function and system structure
of
steel
manufacturing process. Modeling
of
system is effective to understand the sys-
tem function, system structure and cross-relevance among different functions
furtherly.
The evolution and development
of
steel industry telI us that the operation
modes
of
complex manufacturing process are usualIy with the competitive nature.
The results
of
competition show that only one mode, or several modes existed
stably under certain external conditions. As a method to describe process system
characterized by dissipative structure, the conception
of
modality has great advan-
tages. Compared with description
of
micro-structure, we need not to know about
nemerous coordinates for degree
of
freedom
of
alI particles (atoms or molecules),
just only several parameters is needed for mode configuration. We should search
step by step to describe the macroscopic orderly state with several parameters (or
degree
of
freedom) in the steel manufacturing process.
Chapter 4 Analysis and Integration
of
Manufacturing Process
of
Metallurgy 113
4.4.5 Combination
of
process science andinformation technology
Steel industry is a kind
of
process manufacturing. Application
of
information
technology in the steel manufacturing process is mainly embodied with the for-
mulation or reflection on process, the control
of
process and devices and feed
back from them, as welI as the evaluation and optimization
of
process system . A
control strategy
of
process system will be gotten through improvement gradually.
The control strategy
of
process system is mainly used for regulation and opti-
mization
of
the most important parameters
of
the manufacturing process. Through
that the specific functions
of
various procedures are realized steadily. Along with
the multi-factor mass flow runs among procedures orderly under the direction
of
objective state, the control strategy will present requirements like heredity, con-
junction, variation, transmission, feedback, etc.. Certainly, the control strategy
of
the process system should both run through every procedure and make a series
of
optimum objectives realized at respective procedure.
Steel manufacturing processes are characterized by operation in series connection,
and integrated production. The information is the linkup to dynamically regulate
functional factors
of
manufacturing process, as well as one
of
important basis
of
integration-optimization
of
the process. By analysis
of
the information flow
of
steel
manufacturing process, the input set
(J)
of
each procedure in the process becomes
related output set
(0)
after the interaction in various procedure
(~)
.
The transforma-
tion from input set to output set is controlled by the set
of
procedure's functions (F)
and procedures' relations (R). The corresponding information subsystem will tum
up in every level
of
this process under the regulation
of
the set
of
control strategy
(C), and then it is integrated to the decision-making center to form the correspond-
ing information system
of
manufacturing process(Fig. 4.5).
Scheduling system
Decision-making ststem
Control system
Physical system
Operation system
.................:": .
: f.n :
...
~
Fig. 4.5 Schematic
of
the relationship between steel manufacturing process structure
and information system
114 Metallurgical Process Engineering
In sum, combination
of
process science with information technology will be
helpful to describe physical model
of
process system excellently, furthermore
contributing to the effectiveness and the reliability
of
mathematical model.
References
Kavanagh L, Carson C, Dasgupta B, et al (1998) Steel industry technology roadmap.
AIME, Han Jingtao , Wang Fuming et al tromstred, Science Press, Beijing
National Research Council U.S.A, (1990) Translated by Beijing Institute
of
Aeronautical
Materials et al. Materials Science and Engineering for the 1990 s. Aviation Industrial
Press, Beijing, (in Chinese)
Shen X F, Hu
G,Jiang L (1987) Dissipative structure. Shanghai People's Publish ing House,
Shangha i, 90-97 (in Chinese)
Xu G Z (2000) Systems science. Shanghai Scientific
& Technological Education Publish-
ing House, Shanghai, 26, 185-I92 (in Chinese)
Yin R Y (1997) The multi-dimensional mass-flow control system
of
steel plant process,
Acta Metallurgi ca Sinica 33( I): 29-38 (in Chinese)
Yin R Y (2000) Analysis and integration
of
steel manufacturing process. Acta Metallurgica
Sinica 36(10):1077-1084 (in Chinese)
Chapter 5
Multi-Factor
Mass
Flow
Control
for
Metallurgical Manufacturing
Process
The basic elements of dynamic-orderly manufacturing processes are "flow,"
"process network " and "program
."
"Flow" is the principal material entity of the
manufacturing process's operations. "Process network" consists
of
nodes and
connectors and constitutes the carrier and the time/space limits
of
flow opera-
tions.
And
"
prog
ram" may be seen as the reflection, in theform
of
information, of
the operational characteristics
of
the "flow."
For comprehensive regulation and control
of
the steel manufacturing process it
requires that we thoroughly understand the operational features of the "flow,"
extract physical models that reflect the essence
of
its operations and form a body
of
information that is effective and useful for conducting dynamic and effective
regulation and control of that process.
The process
of
old steel plants consisted of many batch operations. So the manu-
facturing process was frequently intermittent with more semi-product stock and
high energy consumption.
It induced the product mix be universally and made the
general layout complex and jumbled. Due to some traditional concept fettering
and some technical condition restricting, these batch operations have blocked
production efficiency and also have occupied plenty capital.
It
increased cost,
consumed resource and worsen environment, and became "technical bottleneck"
which blocks total rationalization
of
process. Meantime, the connection and coor-
dination among main processes with batch operation's mode has put forward
complex requirements which are not clearly rational. As the above problems that
the batch operation
of
ingot casting and breakdown in steel plant process related
to limitations and uneconomic, many important improvements
of
metallurgical
technology developed to increase continuation and compactness
of
process world-
wide in recent 30 years.
Based on "entirety" topic of continuation/quasi-continuation and compactness
R. Yin, Metallurgical Process Engineering
© Metallurgical Industry Press, Beijing and Springer-Verlag Berlin Heidelberg 2011
116 Metallurgical Process Engineering
in steel plant process, some technologies for different unit procedures and unit
devices have been developed, for example, caster equipment and 100% continu-
ous casting regime, campaign elongation ofBF, BOF, reheating furnace, ladle, etc.
And the further studies on the concept and the theory
of
matter state transforma-
tion, matter property control and related multi-factor mass flow control for effec-
tively connecting, matching, coordinating and running through in whole steel
plant process had carried out. A new technical system
of
optimization in entirety,
continuation/quasi-continuation and compactness has been established. This is a
topic
of
a very complicated problem
of
advance manufacturing technology-
metallurgical process engineering which also intersected with mechano-electronic
engineering, thermal power engineering and information technique.
5.1 Some Fundamentals
of
Multi-Factor Mass Flow Control
A series
of
characteristics which are on aspect
of
the physical essence for metal-
lurgical manufacturing process were discussed in Chapter 4.
It
is indicated that,
on viewpoint
of
physics, metallurgical manufacturing process is a multi-factor
flow. The flow is dynamically and orderly operated according to some program,
completes every physical and chemical conversion/transformation and realizes
muti-objective optimization within a complex process network which is consisted
of
procedures with different functions and linkers among procedures.
5.1.1 Concept and elements
of
manufacturing process
As described above on physical manufacturing process, it may deduce that proc-
ess operation has three elements, which are process network, flow and program.
Their definitions in metallurgical manufacturing process are as following:
I. Process network. Process network is a matter-energy, time
-space
struc-
ture to integrate "flow
of
resource", "node" and "connector" in the opening
process system. This structure requires static rationalization for the space
structure (e.g. the general layout
of
plant etc.). And especially the dynamic
ordering, continuity and compactness should be represented in the flow
of
resource operating.
The "flow
of
resource" contains raw material flow, energy flow, and related in-
formation flow at inlet, also mass flow, energy flow and related information flow
in process running, as well as product flow, by-product flow, any other emission
flow with information flow out (Fig. 5.1).
These "nodes" mean procedures and devices with different functions in the
process network, such as BF, BOF, etc. These "connector" are the connecting
measure, mode and facilities among nodes, such as pipe, roll conveyer, railway,
crane, vehicle, steel ladle, iron ladle, etc. Therefore, process network also may be
Chapter
5 Multi-Factor Mass Flow Control for Metallurgical Manufacturing Process 117
regarded as the optimized configuration and the space-time boundary among the
nodes and the connectors.
Energy flow
--
..........
Information Information flow
flow
o Node (procedure. device)
Connectortroad, pipe. roll conveyer. crane. railway. ladles etc.)
'v""v-
Multi-factor mass tlow(operating process)
Fig. 5.1 Sketch
of
conceptions and elements in manufacturing process
If
the process network becomes irrational, the behavior
of
flow should operate
as disorder
of
the time-characteristic factors or present chaos state always, more-
over, it brings the information
of
operating and controlling program
of
process
passively and confusedly. In this way, it should increase the dissipation
of
mass
flow and energy flow.
As a whole, dynamic order for the metallurgical manufacturing process not
only depends on each factor, such as the procedure/device, respectively operating
orderly and relative steady, but also is influenced, restricted or promoted by the
process network, such as flowchart, layout, etc.
2. Flow.
Flow is generally refer to running characteristics
of
operated different
resources including matter, energy and information in the opening process system,
i.e. the variation
of
its quantity, phase state and performance with time. As re-
gard as the metallurgical process, the physical essence
of
the flow for multi-
factors, i.e. chemical composition factor, physical phase state factor, energy and
temperature factor, geometry factor, surface feature factor, space-location factor,
time-sequence factor, has been described in Chapter 4. This multi-factor flow
would be shown as multi-factor character exists in running and controlling
of
the process . The multi-factor character appears that the matter state transform-
ing, matter property controlling and related mass flow controlling are com-
pounded by
mass flow, energy flow
and
informationflow in the operating process.
The
mulli-facler character also is embodied in the process control over basic pa-
rameters(matter quantitt index, temperature, time)and derivative parameters(gield,
performance, cost ere.
)of
manufacturing process.
3. Program. In short,
program in the operation
of
manufacturing process may
regard as collections
of
orders, rules, strategies, paths in many forms. Order in-
cludes array
of
order or disorder and also
of
succession by someone factor. The
order pattern includes function order, space order, time-characteristic order and
spatio-temporal order in addition.
Rule hails from the different demands, the dif-