1. basic principles
In our country thermal power plant, the pulverizer
also in the massive uses, the majority pulverizer also is at the
manual hand control the condition, creates the grinding machine memory
coal amount to change in a big way, makes the powder efficiency lowly,
ton coal consumption electric quantity big, 钢球 and 衬板loses in
a big way, moreover, because the system powdery condition change is
big, powdered coal degree of fineness and the uniformity also with
difficulty guaranteed, is disadvantageous burns to the boiler also
causes to fly the ash combustible substance to increase, imperceptibly
also increased the energy consumption.
In the pulverizer the coal briquette, 钢球 and 衬板mutually
collides has the noise, this noise changes along with the pulverizer
internal installation coal amount change. The coaling compares
the youth, 钢球, 衬板collision probability big, energy big,
produces the noise is big; Along with installs when the coal
amount increases, because of coal briquette unceasing packing,
钢球, 衬板the collision probability reduces, can the
quantitative change be small, the noise which produces also reduces.
Therefore, may examine the pulverizer coaling change with the
audio frequency sensor how many. With the aid of the surveying,
electronics, acoustics and so on the multi-disciplinary knowledge,
further installs the coal amount through sound frequency conversion
delivering to the representative the signal to carry on the
enlargement, the filter and the noise characteristic spectrum
recognition, the output conforms to the DDZIII measuring appliance
standard, in proportion to the pulverizer installs the coal amount the
direct current signal. This 传感 changes delivering also to
have the Profibus field bus connection, but conveniently and field bus
system docking.
The pulverizer is a big inertia, the pure lag, the dynamic
characteristic complex object, the mathematical model establishes with
difficulty, moreover its mathematical model also slowly is changing
along with the time variation. In view of pulverizer movement
this characteristic, its basic control strategy is suitable for to use
fuzzy PI. Fuzzy PI is one kind of PID improvement algorithm
which develops in recent years, this control method does not need to
know is controlled the object the mathematical model, may act
according to moves personnel's practical experience to summarize the
fuzzy control rule, and when is controlled the quantity approaches the
given value, uses the PI control, guaranteed is controlled the
quantity to be fast, stably moves in the given value. Our
research indicated that, this fuzzy PI controller can obtain good
moves, the static control performance, may guarantee in the pulverizer
saves the coal amount accurately to be fast stable is supposing the
definite value.
Uses the auto-adapted method to be allowed to cause to produce
supposes the definite value to be able truly to represent and can
real-time to follow the pulverizer the best operating point.
Thoroughly analyzes the pulverizer the performance curve (chart
2 - 1), is helpful to seeks the pulverizer the best operating point,
namely the grinding machine is biggest the point of force. In
chart 2 - in 1, the tonic train signalling is, sees curve 3 which
decreases progressively along with the pulverizer memory coal amount
increase. In order to facilitate in order to, center has carried
on simple processing in sound frequency conversion delivering to the
signal, the curve which which decreases progressively the audio
frequency characteristic curve transforms increases progressively,
like in the chart curve 4 show, by now the signal greatly expressed in
the pulverizer saves the coal amount to be many.
Below through may obtain some conclusions to the pulverizer
characteristic curve analysis:
The a. pulverizer is biggest the point of force namely best
operating point in the chart f2 spot. 
The curve 1 is the power characteristic, the curve 2 for
strives the characteristic, the curve 3 is the audio frequency
characteristic, the curve 4 after the processing audio frequency
characteristic Chart 2-1 pulverizer performance curve B. in pulverizer movement, when its memory coal
amount compares the youth, because 钢球 mutually collides causes the
pulverizer noise (namely audio frequency) the signal to be stronger;
Along with its memory coal amount unceasing increase, 钢球 the
crevice is gradually filled up by the material, thus the pulverizer
noise signal gradually weakens. When the pulverizer strives to
achieve biggest when (in chart f2), 钢球 between filled up the coal
briquette basically, the noise signal has been also invariable.
The reflection in the chart the curve 3, the noise signal
changes extremely smoothly. May arrive after the noise curve is
biggest the point of force the rate of change very small this
characteristic.
The c. pulverizer movement scope may divide is 3 sectors, like
chart 2 - in 1 I, II, III shows. May see: The pulverizer
work is bigger in I zone time power consumption, strives, obviously
not to be slightly inappropriate; The work is easy in III zone
time to stop up the coal, occurs completely fills the accident.
II area is the best movement region, and should cause the
pulverizer the operating point to close up as far as possible to the
f2 spot.
Along with the time change, the chart 2-1 center curve can have
the drifting, but various curves relative position is invariable, uses
the on-line auto-adapted method to be allowed the real-time track to
be biggest the point of force, guaranteed the pulverizer throughout
moves in the best operating mode.
2. essential technologies
This product essential technology is: In
movement process pulverizer internal installation coal amount
intelligent examination technology, system powder system control
strategy, control system hardware architecture modulation, software
function modulation.
Pulverizer internal installation coal amount examination
technology: Uses the independent development intelligence tonic
train signalling 传感 - to change delivering to realize.
Should change the delivering core to use the DSP processor, may
realize the tonic train signalling frequency band choice, the digital
filter, the energy integral, 有效?function and so on
transformation, its function is picks out in the pulverizer movement
noise with installs the frequency band which the coal amount
corresponds, filters the mechanical noise, and carries on the energy
accumulation to the correlation frequency band and 有效?the
transformation, thus indirectly obtains in the pulverizer to save the
coal amount. Its result may use 4 ~ 20mA simulation quantity
output, also the passable Profibus-DP field bus has transmitted.
Tonic train signalling 传感 - changes the delivering structure
like chart 2-2 to show:
 Grinding machine load control strategy:In view of when pulverizer big inertia, pure lag and
parameter changes the characteristic, uses the control strategy and
the double-decked control structure which auto-adapted - fuzzy PI
unifies, like the chart 2-3 shows. In the chart the auto-adapted
controller function is suitably produces to suppose definite value R;
But the fuzzy PI controller had guaranteed is controlled the
object the output to be allowed to follow should suppose the definite
value.
The auto-adapted introduction, enables the control system the
real-time track to be biggest the point of force, guaranteed the
pulverizer throughout moves in the best operating mode, thus truly
gets up the effect which the energy conservation falls consumes.
Auto-adapted - fuzzy PI unifies control strategy, not only may
guarantee the pulverizer throughout moves under the optimum condition,
moreover can achieve the safe energy conservation, improves the
product quality and the output goal.
Chart 2-3 pulverizer auto-adapted - fuzzy PI control
system Pulverizer load control system hardware
architecture modulation: Has promoted the direct digital control
in view of the thermoelectric power station different pulverizer type
(DDC), the small scale field bus control system (FCS) and fuses and so
on the realization way with the existing large-scale DCS system,
enable the system to have the compatibility and the versatility.
Uses the DDC system to realize the pulverizer load control, is
suitable less (for example only has 1-2) to the pulverizer quantity
situation, this time, the pulverizer load control system already may
from the adult department, also may conveniently Lian Ruyi have the
control network, has the structure to be compact and the ease of
operation characteristic.
To has many pulverizers the power plant, uses two levels of
distributional collections control system structure which like the
chart 2-4 shows, may guarantee the system has a higher reliability,
some single return route regulator appears the breakdown only to be
able to affect this grinding machine system, cannot create to the
neighbor grinding machine control system not good affects. In
addition, because each pulverizer system all may use a regulator or
the PLC system carries on the control, therefore control algorithm
compilation, debugging and revision all very convenient, is easy to
obtain the good control effect.
The small scale field bus control system (FCS) not only may
realize the grinding machine load control, also is extremely easy to
expand to the entire system powder system control and the
surveillance, replaces the original measuring appliance control
system, enhances the entire factory the automated level, this plan
especially suits to has not carried on the FCS system transformation
the middle and small scale power plant.
Chart 2-4 small two levels of distributional field buses
control system structure drawing Uses the large-scale DCS existing software and
hardware realization grinding machine load control, may achieve the
grinding machine load control and the existing DCS system complete
fusion, also because fully used DCS to be possible the extension, did
not need to supplement excessively many investments, and was allowed
greatly to reduce the system development and the maintenance work
load, to has realized the DCS technological transformations enterprise
to say is implementation plan which one kind was worth recommending.
This plan rubs the intelligence the sound sensor the signal
provides to the DCS system through the field bus or the simulation
quantity, the control logic uses the DCS configuration realization,
the work load slightly, but the reliability very is actually high.
Software function modulation:This product has developed set of small configurations
software in view of the thermoelectric power station pulverizer
control, the above each kind of control system besides uses the power
plant existing DCS systems control, may use this configuration
software to carry on the programming and the monitoring, has achieved
the software function modulation, is more advantageous to the product
promotion and the application.
In summary, this system because uses the audio frequency 传感
- transmission gearbox, in domestic took the lead to solve the
difficult problem which the thermoelectric power station pulverizer
load was unable accurately to survey; In view of the pulverizer
movement characteristic, in domestic and foreign first proposed the
auto-adapted - fuzzy PI control unifies the control strategy and the
double-decked control structure, finished the thermoelectric power
station pulverizer load not to be easy to control or the control
effect not good history since long ago; Is different according
to each user needs with the request, has used the hardware modulation,
the software modulation structure, suits the Chinese national
condition and the scene reality, and the promoted application has laid
the solid foundation for the system product, thus causes this system
to become discipline union the and so on collection surveying,
electronics, computer science and automatic control high tech product.
This product can realize the ball mill electricity saving
10-35%, reduces 钢球 衬板10-30% cement to increase production
above 10%, increases degree of fineness, reduces the noise, lengthens
the machine useful life of equipment, the investment repayment
contract is about a year, the technology is in the lead the
international standard, the investment recycling time is short, mainly
applies to the power plant, the cement plant, the ceramic factory as
well as all applications ball mill enterprise, has the very widespread
market prospect |
