Yin R. Metallurgical Process Engineering
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118
Metallurgical Process Engineering
ferent external conditions and the entire function
of
process, for example, the con-
tinuation and compactness
of
process running, which are main response
of
the rule.
The combination
of
order and rule reflects the whole controlling strategies and the
detailed operating paths
of
multi-factor mass flow inmanufacturing process.
5.1.2 Dynamically
and
orderly operating
of
process
A. Conditions of dynamic
order
operation
The steel manufacturing process belongs to dynamic orderly structure
of
macro-
scale. Dynamic orderly structure is dissipative, coming
of
process dissipation.
The static order character on aspect
of
space, time and functions in metallur-
gical manufacturing process is obvious. Since the process is always arranged by
the spatio-temporal order
of
raw material yard
-sinterlcoking
-ironmaking
-
hot metal pretreatment
-steelmaking
-secondary
metallurgy
-solidification
-
reheating-hot
rolling, success is primarily owed to the design, specially the
layout. The extent
of
ordering depends on the ideas
of
entirety while designing.
Another key problem is how to operate the process dynamically and orderly in
manufacturing, namely, to realize linking and coupling by optimization
of
pro-
cedure functions and interaction (coordination or restriction) among procedures.
The continuation/quasi-continuation and compactness
of
process will come
of
synergetic and rhythmizable ways
of
process in multi-factor mass flow running.
As known in dissipative structure theory, the condition
of
formation
of
the dy-
namic orderly structure, at first, is the open system. That is different from prereq-
uisite to isolated system in the classic thermodynamics. In fact, all the manufac-
turing processes in process industry are open systems, which exchange matter and
energy with surroundings including input and output flows. Another condition
of
dissipative structure is the process system to be irreversible and far away from
equilibrium.
I. Prigogine(l977) indicated that the open system
of
nonequilibrium
may construct a stable orderly structure by the fluctuations with nonlinear interac-
tion in the system under some controlling conditions. Therefore, on the view
of
the state and process
of
system, steel manufacturing process is the same as most
manufacturing processes which have the conditions
of
dynamic orderly structure.
B Driving power of dynamic orderly operation
Above conditions being over, the driving power should be found to form dynamic
orderlystructure. For steelmanufacturingprocess,the drivingpower will be:
• Fluctuations
of
component (procedure or device) behavior. For an instance,
tap-to-tap time
of
one converter heat is defined as 30 min, but it is possible within
28
~32
min with different probability in practice. This is the fluctuations on pro-
cedure or device scale. Certainly, the fluctuations are also appeared on tapping
Chapter
5 Multi-Factor Mass Flow Control for Metallurgical Manufacturing Process 119
temperature and composition etc.
• Nonlinear coupling
of
component interaction with each other. Due to the
functions
of
each component's self in process are different, meantime, behaviors
of
component (procedure/device) are fluctuating, therefore, the basic parameters
as quantity index
of
matter, temperature, and time are uneven in process.
It
in-
duces that relations
of
components with each other must be nonlinear. For an in-
stance, linking temperature between caster and reheating furnace may be ?::200°C,
or ?::600°C, even ?::1000°C, so the state
of
linkage and relation
of
processes
under different temperature between caster and reheating furnace are nonlinear.
• Component (procedure/devices) being far from equilibrium. This is certainly
the result
of
opening and irreversibility
of
process system.
Therefore, the desirable state
of
dynamic orderey operation is just dissipation
deduced by self-coupling
of
fluctuations, irreversibility, nonequilibrium and open-
ing
of
procedures or devices on time axis through nonlinear coupling among them.
Dissipative structure itself possesses the inherent "self-organization" function.
The running state
of
dynamic order process, on some meaning, is evolution
of
complexity and time-characteristic factor in the process.
The problem
of
order parameters in process must be analyzed on synergetic
view for further improvement
of
process structure and operation state.
Synergism figures out, a great number
of
variables, which affect system behav-
iors, always force the system return to initial stationary state when the system is
disturbed and then fluctuated. These variables act as one damping effect and at-
tenuate very rapidly, so they have less influence on the process
of
structure con-
version
of
system. They are named variable
of
quick relaxation. But other few
variables, when system is disturbed and then fluctuated, can make the system far
away stationary state and get nonequilibrium or grow into a new stationary state.
They always determine the procession
of
system evolution, and decide structures
and functions
of
system evolution. They are variables
of
slow relaxation. H.
Haken defined that these variables
of
slow relaxation were order parameters
of
system (Xu, 2000).
Synergism theory points out, the variable
of
quick relaxation relies on the vari-
able
of
slow relaxation, and order parameters control behaviors
of
subsystems.
This viewpoint also is called "servo principle" (Xu, 2000b).
Therefore, would the structure and the operation function
of
the process system
be farther adjusted or optimized, study on order parameters
of
process is the cut-
in point
of
importance, and the keynote to know and cognize the process system.
We must analyze and study in detail on:
• Number, situation and stimulus-response mechanism
of
order parameters in
process;
• Time sequence
of
order parameter appearance in the process, meantime, the
earlier or later
of
their appearance for one more order parameters;
120 Metallurgical Process Engineering
• Possibility
of
synergetic effect and new structure emergence excited by some
order parameters.
C Generation and modality of self-organization function in process operation
Steel manufacturing process belongs to system
of
dissipation. Formation and im-
provement
of
an order state in dissipative system by its self during running may
apparently intitule them as
self-organization. The function
of
self-organization in
manufacturing process is described as above, but reasons and methods to excite the
forming and improving
self-organization function should be much more studied.
Firstly, steel manufacturing process acts as a dissipative structure, itselfhas in-
herent
self-organization nature in dynamic operating, as each process's compo-
nent (subsystem like procedure) has the tendency to fluctuations, and then related
nonlinear interaction among components in the process running. These fluctuating
tendency and nonlinear interaction under such attractive factors as dynamicorder
and process continuation have made inherent
self-organization performance
of
system evolution by its own.
Secondly, after recognization
of
the inherent self-organization nature
of
the
process's own, people understand that the new manufacturing process may be
established by researching its order parameters, such as analyzsis-optimization
of
set
of
procedure's functions, coordination-optimization
of
set
of
procedures' rela-
tions and reconstruction-optimization
of
set
of
procedures. That is the new dissi-
pation operation with more advantages. The extent
of
fluctuations
of
each com-
ponent (procedure, device) and the nonlinear coupling relation among them are
further optimized and more stable in the new process operation. So dynamic-
ordering and process continuation running are much more realized that strengthen
the inherent
self-organization
of
process system.
Then, any information in process will be received and described to formulate
the physical-mathematical models and to calculate and control the process run-
ning with computer. On some meaning, this is man-made construction on some
functions
of
self-organization.
According to above discussions, self-organization
of
process system is to form
certain functions and structures
of
process by the attractive requirements (dy-
namicorder and continuation/quasi-continuation), with effect of interactions
among components
of
the process system under some conditions. The most im-
portant research is the characteristic analysis
of
the process system constructed
from
self-organization, being more ordered and more continuous steady than be-
fore. Certainly, this is mainly analysis on order degree, especially the comparision
of
process mode on aspects
of
function, time and space as well as on the state
steadiness before and after
self-organization. The steady state
of
space ordering,
time ordering, time-space ordering, function ordering in process system may be
shown through comparision.
Self-organization may be analyzed and compared by
Chapter
5 Multi-Factor Mass Flow Control for Metallurgical Manufacturing Process 121
order degree, and the type
of
process system may be distinguished by kind
of
or-
dered states, and so on.
Self-organization in process operation is a dynamic proc-
ess, the dynamic characteristics are not only represented in state variation during
self-organization, but also in feature
of
steadiness selforganized process system.
Self-organization is rich and colorful, has many modalities: mainly self-
generation, self-reproduce, self-growth,
and self-adaptation(Xu, 2000c).
1. Self-generation.
Self-generation is an explanation on self-organized state by
comparing new forming state with old intrinsic state in
self-organization.
Self-organization
is analogous to phase transformation in the process
evolvement. In some outside conditions, process system will spontaneously
generate new structure and function from intrinsic unstable and disorder
state by interaction among components (procedures, devices)
of
the process,
and become a new state, which
didn't
exist before. This self-organization
mode is self-generation.
The characteristics
of
self-generation are that the process system produces new
state, new structure and new function which are not in original phase. These new
state, new structure and new function with respect to original system state before
self-generation can not analyzed by some organization theory. For example, con-
tinuous casting instead
of
ingot casting-blooming in steelmaking process leads the
relations between solidification and smelting or rolling to an obvious change. The
new high temperature linking and process structure
of
relatively high continuity
and the new operation function
of
ordered mass flow have appeared. Vast varia-
tion
of
the fully continuous casting in steel manufacturing process was not fore-
casted by the organization theory
of
system engineering.
Comparing the new state after
self-organization with original state, if
order degree is increased, the
self-organization is mean as self-generation,
contrariwise,
if
order degree is decreased, the self-organization is mean as
self-collapse. Some self-collapse had appeared in steel technical reconstruc-
tion, for example, the new devices were added random disregarding ration-
ality
of
layout, or the workshop was laid confusedly, as well as universality
of
product mix were taken for production expansion temporarily. When self-
collapse
appeared in technical reconstruction
of
steel manufacturing process,
which always brings negatives that the loss overweighs the gain with long-
term and whole situation.
2. Self-reproduce.
Self-reproduce is depiction
of
state characteristics from
self-organization, in case
of
which components how interact each other to
ensure the process system being ordered and stable. Time structure, such as
tap-to-tap time induced by
self-organization in process system is the simplest
aspect
of
self-reproduce. Self-reproduce analyzed relations and features
among process states each other through time procession
of
self-organization.
Evolution
of
process system shows ordered state in self-organization. On ana-
122
Metallurgical
Process
Engineering
lyzing with time progressing, the new pattern which appears after a time pe-
riod is same as the original pattern, this kind
of
evolution is named as self-
reproduce.
For a process system consists
of
many components (many subsys-
tems), state
of
process system in whole is changeless, namely, keep original
operation on viewpoint
of
entire process system. But from viewpoint
of
sub-
system level, the state varies and every component (subsystem) is all varying.
So we easily observe
self-reproduce
of
components (procedures, devices)
of
process system in majority instance. The function
of
self-reproduce
of
com-
ponents
just
keeps the ordered state through self-organization in process sys-
tem.
Self-reproduce is ground for stable existence
of
state made from self-
organization.
The time
scheduling-operation
chart for producing some prod-
ucts in the steel plant belongs to a kind
of
self-reproduce. This self-reproduce
on subsystem level shows repeatedly appeared time-order on each component
(procedure, device).
3. Self-growth.
Self-growth is depiction
of
state evolution with time on process
integral scale, and is analysis for state
of
process in entirety. Structure and func-
tions
of
process keep invariable in self-growth. Self-growth relies on a certain en-
vironment, such as input
of
matter, energy and information, to become averagely
the power
of
process system, and to enlarge the integrity by self-organization
of
the process system and/or interaction among components. In major instances, self-
reproduce
of
components (subsystems) is the reason
of
self-growth
of
the process
system. For example, periodic operation
of
converters and rolling mills shows
self-reproduce
of
components, but the manufacturing process
of
steel plant is in-
cessantly running under quasi-continuation. The raw materials, energy and infor-
mation are imported, products and by-products are delivered, and some wastes are
recycled, so the operation more and more goes along with time. Hence shows the
evolution
of
self-growth.
4. Self-adaptation. Self-adaptation is depiction
of
process system concerned in
its relation with outside environment.
Self-adaptation announces that process sys-
tem responds to environment and appears new structure, new state or new func-
tion to adapt outside by
self-organization in certain conditions .
Self-adaptation is seemed as self-generation that both
of
them want to ana-
lyze the whole
self-organization and to study the differences
of
states before
and after
self-organization
of
process system. But they are different, self-
generation
is analysis on characteristics
of
self-organization in process system,
and on new structure and new functions which are appeared in process system
after
self-organization.
It
is description on process's own states and discussion
on internal behavior mechanism in process system.
Self-adaptation in system is
response by stimulus due to outside environment change, is analysis and re-
search on characteristics
of
self-organization from view
of
relation between
process system and surroundings. Therefore, in same one instance, issue
of
in-
Chapter
5 Multi-Factor Mass Flow Control for Metallurgical Manufacturing Process 123
ternal interaction in system is self-generation, issue
of
relation between system
and surroundings is
self-adaption.
On discussion
of
a certain practical problem,
if
process system was non-
structure and disorder before
self-organization, there appears new structure
which emerged from internal interactions, is referred to
self-generation.
If
a
certain structure state existed in original process system and it is changed by
stimulus from outside environment changing, this phenomenon is named
self-
adaptation. Self-adaptation
emphasizes that the ordered state in process sys-
tem will be changed by variation
of
the environment, even
if
the structure
of
process system had been ordered. That is embodiment
of
the ability on envi-
ronment adapting.
The above classification on
self-organization is described and analyzed on dif-
ferent views, levels and scales. In practice,
self-organization is complex that
many hybrid patterns appear with different degree in most case. So that, when
practical problem
of
self-organization is analyzed, it must be observed and ana-
lyzed on many positions.
5.1.3 Targets, contents and methodology
of
study on multi-factor
massflow control
General target
of
study on multi-factor mass flow control in steel plant is
study on feature, state and outside conditions from beginning
of
process dy-
namic-orderly running, that is study on self-organization in itself
of
process
and on order parameters in process operation through the dissipative structure
to develop into continuation/quasi-continuation and compactness
of
the steel
production process. The further purposes are to improve market competitive-
ness, to promote sustainable development and to
join
in circular economy
of
society.
Main contents
of
research on multi-factor mass flow are:
• Structures and behaviors
of
manufacturing process;
• Interrelations between correlating/adjacent levels in process;
• Functions, structure and efficiency
of
each component in process;
• Interactions among components in process etc.
Main methods for research multi-factor mass flow
of
steel plant are:
• The fluctuations and theirprobability
of
each component running in process;
• Nonlinear relationon interactions
of
each components' operation in process;
• Function
of
self-organization existing in dissipation-process operation;
• Order parameters
of
process running and their contribution to new structure
emerging;
• Influences on process structure and its operation state from outside condition
and their adaptation with each other.
124 Metallurgical Process Engineering
5.2 Multi-factor Mass Flow System Control
of
Steel Manufac-
turing Process
The process features
of
steel manufacturing process, concept
of
operation in steel
manufacturing process and analysis on stimulus-response
of
manufacturing proc-
ess system are described in this part as
fol1ows.
5.2.1 Process features
of
steel manufacturingprocess
A. Abrief review
Evolution
of
steel manufacturing process has induced variation
of
steel plant pat-
tern generation by generation, but the essential characteristics
of
matter state
transformation and matter property control are not significant change in metallur-
gical process. Production process
of
steel plant contains chemical metallurgy and
metal1urgical physical process
usual1y.
Chemical metal1urgical process is mainly
interested in embodying relations among composition, temperature and time. The
metallurgical physical process does interest in relations among deformation, mi-
crostructure, temperature and time mainly. The connection region between
chemical metallurgy and metallurgical physical
process-solidification
of
steel
had taken invaluable change from 1970s. This provided variation is key
of
the
most active factors to promoting modern steel production development, it is the
order parameter
of
entire operation
of
process practically. After steel continuous
casting technology is adopted, the duration
of
steel casting procedure shortens,
the process efficiency improves, and the temperature undulation
of
metals de-
creases.
It
has induced some procedures such as ingot casting and blooming,
which belongs to slow relaxation variables, to be eliminated. Then the bottle-
neck
of
mass flow in operation process is opened in some degree. These have
driven process to integrated optimization. So a great change in plant pattern,
mill scale, product mix, investment and market competitiveness
of
steel plant
has arisen.
B. Combination of matter state transformation, matter property control and
mass flow control in production process-multi-factor mass flow control
system
In the view
of
engineering, the essence
of
steel production process is the technol-
ogy
of
matter state transformation and matter property control, such as phase
transition and state control, steel grade and quality control, metal shape-size and
surface feature control, as well as product performance control etc. On the other
Chapter
5 Multi-Factor Mass Flow Control for Metallurgical Manufacturing Process 125
hand, the essence is control on multi-factor mass flow
of
manufacturing process,
this mass flow control is not only material transport, but also optimized connec-
tion and matching
of
main parameters, such as reasonable linking for flowrate,
temperature and time-point
of
mass flow, matching for inlet and outlet flowrate
between adjacent procedures, buffer and coordination
of
time rhythm, optimiza-
tion on transport direction, distance and ways
of
mass flow, compactness
of
mass
flow etc. These parameters are very important to influence plant pattern, invest-
ment, input-output benefit and even environment burden
of
steel plants. So that,
in viewpoint
of
engineering science, characteristics
of
steel manufacture are coor-
dination-optimization for the matter state transforming, the matter property con-
trolling and the mass flow controlling in process. Through improvement and
soundnesson functions
of
a seriesoftechniques and devices, and with comprehensive
applicationof automationtechnologyinprocess, theguidance to development pattern,
investment direction, investment sequence, and specific investment
of
steel plant
may be gained in time and effectively. Matter state transformation, matter prop-
erty control and mass flow control are always undergone simultaneously and/or
respectively reqarding ferruginous mass flow in steel production process. The
present case
of
mass flow in steel manufacturing process is quasi-continuous
and/or batch running in general.
It obviously differs from the logistic systems
of
railway transportation, postal mail distribution, logistic system for chain stores,
also from mass flow in automobile assembly line or machinery cold processing
line. The mode
of
mass flow in steel production results in a multi-factor mass
flow control as shown in Fig. 5.2.
Sinter/pellet Blast Converter Continuous Hot rolling
/- " furnace castmg mill
A0 "- Ilot metal Secondary Reheating
Raw material ,,/ ,
_/
<,
treatment metallurgy furnace
d
""'
-Y
y
-"
"....
.....
-, /
-,
/-"
/-
---.....
/' -
yar ( 1 10
1-
---(0
}-
__
-i 0
I---
-{ 0
1----
1
0
'r----{
0 'r-----i 0 i
'
............
4..
......
/ _
.",..-"""'
_
.....
'
......
_/
\
.....
_/
,
_/
\ .._ /
,_/
, _
........
' I O
r/
'
-'
Coking
---
Matter state transformation, matter property control
- - - Matter flow
Fig. 5.2 Schematic diagram
of
matter state-matter property-mass flow
in stee l production process
The multi-factor mass flow in the steel plant has been discussed briefly m
Chapter 4.3. As cybernetic engineering
of
multi-factor mass flow in steel produc-
tion process, the connection, matching, continuation and steadiness
of
the follow-
ing parameters must be considered:
• Transformation, tran
sf
er, connection and matching
of
state, composition and
quantity
of
mass flow;
• Coordination, buffer and acceleration on time rhythm
of
mass flow;
• Solidification
of
liquid metal into slab/billet with ordinary shape and size, and
126 Metallurgical Process Engineering
then the deformation and coordination
of
shape and size
of
slab/billet in mass
flow process;
• Conversing, transferring, coordinating and saving
of
energy in mass flow
process;
• Variation, heredity and control
of
metal surface quality, macrostructure, mi-
crostructure and steel performance in mass flow process;
• Adjustment, coordination and optimization
of
materials transport route and
way.
To realize the coordinating and matching on above parameters, it not only must
improve functions' optimization
of
procedures, equipment reliability and control-
lability
of
each procedure, but also pay more attention to the flexible adjustment
on adjacent procedures each other. Based on the optimum and match
of
abilities
of
capacity and function
of
procedures/devices in the process system, the flexible
buffer engineering, playing role
of
combining, linking up and adjusting between
relevant procedures, i.e. the self-organization function is formed. In fact, flexible
buffer engineering has incessantly been developed since the middle
of
zo"
cen-
tury with evolution
of
procedure's functions and coordination-optimization
of
procedures' relations. The relations
of
relative flexibility or relative rigidity are
often presented on some functions between neighbor procedures and even more,
therefore, the flexible buffers for different function parameters are composed, and
then the structure optimization
of
the whole process or process section is realized
at a higher level.
5.2.2 Concept
of
operation in steel manufacturingprocess
To abstract the character
of
the steel manufacturing process system and to extract
some essential concepts, the correlation among different functions in process must
be fully understood, the nature
of
functions about existence value
of
procedure
and their relations in process system must be known and confirmed, then the
modeling is abstracted on the base
of
these concepts.
A. Abstract-analogy----stimulus-response
The steel production process system is a manufacturing process with optimum
combine
of
matter state, matter property and mass flow. The process system is
very huge, its processing parameters are numerous, and many parameters are
quickly changed simultaneously or successively in short time. This type
of
change
often faces difficulty on directly measuring these parameters. So, it is very diffi-
cult to describe this complex process system. Therefore, it is necessary to study
the process system through abstract-analogy.
In fluid mechanics, analyzed on fluid stress and strain, the partial differential equa-
tions
of
four dimension system are gone out by tensor method. However,the fluid is
Chapter
5 Multi-Factor Mass Flow Control for Metallurgical Manufacturing Process 127
continuummedium. Analysisof continuum is rather simpler than of dispersedsystem
or quasi-continuous/batch process.
If
the partial differential method is directly
applied on describing a manufacture process, great difficulty must take place. But
on the engineering methodology, stress-strain analysis is the same kind as outside
stimulus-inside response in essence. The essences
of
continuum system and the
essences
of
process manufacturing system have commonness. But obvious differ-
ence between the both sides exists. This difference is: the outside stimulus to
every volume-element in continuum system has uniform even simultaneous inside
response, but the outside stimulus factors, such as variances
of
market, investment,
resource, energy, price etc., call response
of
many components (procedures, de-
vices) in manufacturing process being heterogeneous, anisotropic and with an
extent
of
delay lag.
B. Coherent system and unequal delay
Steel manufacturing process may be abstracted into a coherent processing which
is analogous to viscous fluid flow. For functions
of
each procedure in process are
different, performances
of
every device take some fluctuations, but they have
strongly coherency in quite great degree
-a
certain skill
of
self-organization.
It
is seemly as non-uniform continuous process or quasi-continuous process. When
stimulus generates outside, the responses
of
different components in the coherent
system show different time delay, and have different fluctuations on capacity pa-
rameters displaying, and thus functional parameters have differently selecting or
fluctuating. So that, this coherent system is stimulated, each component
of
system
always has different kinds and delays
of
responses. These process characteristics
need treating by different method
of
self-organization for flexibility-coordination.
One
of
the advantages for this system analysis is that dissipation has source
of
system's own characters (like viscous dissipation
of
fluid), instead
of
artificial
characters. However, process manufacturing system not only has coherency
of
manufacturing system's own, but also takes certain artificially influenced, named
as artificial coherency. Therefore, control
of
process optimization does not be
detached from management fully.
It
is very difficult that steel manufacturing process system takes full flexi-
bility and becomes real continuation.
It
is not necessary over pursuing on-site.
Since, the system
of
quasi-continuation or definite setting flexibility must be
sought now.
C. Description on quasi-continuation and/or batch operation
The basic condition
of
system description with differential equations is that the
continuously differentiable independent variable is contained in the system. There
are three continuously differentiable independent variables as the quantity index
of
matter, the temperature and the time in both chemical metallurgy and metallur-