FIELD OF THE INVENTION
The present invention generally relates to a system for online monitoring and
estimation of Coal Particle Size Distribution after the coal particles get
pulverized by pulverizers and before they enter into the furnace area to get
burned to release heat energy. The system of the invention is enabled to
sample, sieve by vibration and collect the sieved coal particles for weighing,
estimating the number of average sized coal particles in a predetermined
ranges with respect to the weight recorded, and provide overall coal particle
size distribution in the range of interest including transmitting the information
to store into the plant DCS in the control room.
BACKGROUND OF THE INVENTION
Before coal is burnt to generate heat, it is first pulverized into a smaller sized
particles and then mixed with air in a stoichiometric ratio for complete
combustion of coal to generate heat energy efficiently. The volume of the
furnace has its own inherent behavior and requirements; also inherent
limitation of pulverizers to get one uniform sized pulverization leading to coal
particle size ranges between certain lower and upper particle sizes which
varies from application to application. Whenever “size of the particle” is used,
it refers to “diameter of the particle” in the disclosures made hereafter, and
particle size distribution refers to a method of sorting coal particles sizes from
minimum to maximum with number of particles for each size of the coal
particle. It is experimentally noticed that certain distribution of the coal
particles have efficient combustion for given design, whereas deviation from
the suggested distribution, leads to inefficient combustion. The inefficient
combustion leads to higher pollutants and higher cost of energy generation.
In case the distribution has more lower sized particles, then these smaller
particles escape without fully burning and become part of fly-ash. In the
other case, i.e. if the particles are higher in size, then these particles fall

without fully burning due to gravitational pull, and become part of bottom-
ash. All the scenarios suggest that maintaining the range with appropriate
distribution between suggested lower sized coal particles to higher sized coal
particles is an important requirement for efficient combustion in the furnace
area. There is a variety of methods that are proposed by inventors and
researchers to address these requirements. In the current invention, a
method and a system is proposed to estimate the distribution of the
pulverized coal particles sizes, particularly using automated vibration based
sieving method after which the particles are weighed that are accumulated in
each of the sieving pane and then weight of the particles is correlated with
number of particles with respect to the sizes.
EP0435570A1, teaches a method of measurement of size and distribution of
particles and voids. More specifically, this invention relates to a method of
measurement that includes scanning an image of a sample of particles,
obtaining chord data along a scan line, and mathematically converting chord
data to particle diameter.
US7177487B2, discloses a method to determine particle size using image
analysis. The method is particularly suitable for small particles such as those
that are less than 1 um in size by scanning electron photomicrographs.
US 2007/0229823A1, describes methods and apparatus for determining the
number concentration and size distribution of particles using dark-field
microscopy. The embodiments are especially useful for the simultaneous
determination of particle number concentration and size distribution of
particles with dimensions below 500 nm. The invention transcends several
scientific disciplines such as polymer chemistry, biochemistry, molecular
biology, medicine and medical diagnostics.

US2010/0169038A1, teaches processes employing algorithms and methods
for calculating particle size distribution. In particular, the present invention
provides processes employing algorithms and methods for calculating particle
size distribution of different particle shapes from chord length distributions.
US2014/0320639A1, teaches a system for estimating size distribution and
concentration of aerosols in an atmospheric region including a digital camera,
a sunlight attenuation filter, and a processor. The filter is aligned between the
sun and the camera’s aperture. Image processing is performed on an image
captured when the filter and the sky are in focus of the camera.
CN102890050B relates to a method for correcting laser particle size using
sieve analysis and data analysis. The present invention relates to a method
for correcting a laser particle size sieve analysis method and analysis of data,
belonging to the field of particle size analysis technique. Finally, the
correction formula to correct the laser particle size analysis of a sample by
sieve analysis particle size analysis, or vice versa.
US5059310A describes a vertical set of sieves receiving the particulate
material from a vibrating trough conveyor above the set and is vibrated by an
agitator on the machine frame. The sieves are spread apart and then tilted to
dump the collected particles into respective funnels. The set can then be
swung back and contracted for the next stage. The funnels are connected to
collectors which are automatically weighed.
EP0620765B1, relates to a particle size analyzer comprising a conveyor, drive
means for moving the conveyor, a set of sieves of graduated mesh sizes,
means mounting the sieves in a set in mesh size order, means for shaking the
set of sieves to cause particles of different sizes deposited on a topmost sieve
of the set to fall downwardly and be retained on the respective sieves
according to particle size, weighing means for receiving and weighing

particles dumped from the respective sieves characterized in that conveyor
with substantially vertical run, the conveyor being movable around a
horizontal roll at the bottom of the vertical run, and in that the sieves are
individually mounted in the set for movement with the conveyor around the
roll, movement of the conveyor advancing the sieves around the roll, each
sieve being inverted as it passes around the roll and thereby dumping the
particles on that sieve.
US4487323A, relates to an apparatus which can automatically make a screen
analysis of a granular material. The heart of the apparatus is a polygonal
drum having graded screens on each of the faces except one. This open face
serves as a door for introducing a sample into the interior of the drum and for
discharging any material larger than the largest screen. A gear motor and
crank arrangement serves to longitudinally shake the drum and agitate the
sample. A second gear motor indexes the drum from screen to screen after a
predetermined shaking time. Each screen fraction is accumulated on an
electronic scale with weights being determined by differential weighing. The
gear motors are timed by a microprocessor which also receives screen friction
weight inputs and calculates a screen analysis.
US4116824A, relates to an automated wet sieving apparatus and process
comprising a wetting liquid distributor which is coupled by eccentric disks to a
motor which drives the distributor in an orbital path for supplying the liquid
onto a sieve. Means are provided for creating alternating vacuum and
pressure below the sieve. The vacuum draws undersized particles whose size
is being determined through the sieve and the pressure loosens blinding
particles from the sieve. Preferably, the sieve is cyclically tilted as the wetting
liquid is being distributed onto the sieve.

US4989464A, relates to a method and apparatus for determining particle size
distribution of lightweight material such as shredded expanded polystyrene.
An agitator cap assembly initially contains the material and agitates it to
avoid clogging, etc. A plurality of sieves are stacked on a receptacle, and the
material is driven from the agitator caps through the sieves. The amount of
material retained on and passed through the sieves provides a measure of
the particle size distribution.
OBJECTS OF THE INVENTION
It is therefore an object of the present invention to propose a system for
online monitoring and estimating the pulverized coal particle size distribution.
Another object of the invention is to propose a system for online monitoring
and estimation of Coal Particle Size Distribution, which is enabled to collect
coal particles sample, and sieve the particles in an automated vibratory
platform.
A still another object of the invention is to propose a system for online
monitoring and estimation of Coal Particle Size Distribution, which transmits
the particles through a vacuum pump to the weighing device one after other.
A further object of the invention is to propose a system for online monitoring
and estimation of Coal Particle Size Distribution, which allows to compute the
weights of particles collected in each sieving pane.
Yet another object of the invention is to propose a system for online
monitoring and estimation of Coal Particle Size Distribution, which is enabled
to estimate number of coal particles collected in each sieving pane.

A still further object of the invention is to propose a system for online
monitoring and estimation of Coal Particle Size Distribution, which allows to
visualize the estimated number of collected coal particles including preparing
a bar chart on the data and store the data in the plant DCS.
SUMMARY OF THE INVENTION
The present invention relates to a method and a system for online monitoring
and estimation of Pulverized Coal Particle Size Distribution, after the location
where coal gets pulverized by pulverizers and before entering into furnace
area. Furnace area is the place where coal burns in the presence of
stoichiometric air to release heat energy. The invention describes a system of
sampling, sample segregation, collecting sieved particles for weighing the
particles, analyzing the weighed particles estimate the number of coal
particles, and store distribution data based on each sieving pane. Particle size
band is divided into “K” ranges. Minimum particle size is “X1” and maximum
particle size is “X2”, which makes “K-2” number of sieving panes. Additionally,
two panes are also used to collect the coal particles that are smaller than the
“X1” and sieving pane with larger than the “X2” respectively; making it “K”
panes with graduated screening mesh sizes. However, the bottom most pane
does not have screening mesh.
In contrast to the prior art discussed hereinabove, the present system for
monitoring and estimating the distribution of pulverized coal particles unlike
as compared to the invention discussed in EP0435570A1, which is on a
method which relates to the measurement of size by chord length and
distribution of latex particles and voids in paint industry; or the invention
discussed in US7177487B2, which is particularly suitable for small particles
used in pharmaceutical industry such as those that are less than 1 um in size
by scanning electron photomicrographs; or the invention discussed in

US2007/0229823A1, which is on embodiments of the invention relating to
methods and apparatus for determining the number concentration and size
distribution of particles using dark-field microscopy with dimensions below
500 nm in several scientific disciplines such as polymer chemistry,
biochemistry, molecular biology, medicine and medical diagnostics; or the
invention discussed in US2010/0169038A1, which is on processes employing
algorithms and methods for calculating particle size distribution of different
particle shapes from chord length distributions; or the invention discussed in
US2014/0320639A1, which is on a system for estimating size distribution and
concentration of aerosols in an atmospheric region; or the invention
discussed in CN102890050B, which is a calibration method for laser coal
particles size distribution by an offline sieving analysis; or the invention
discussed in US5059310A, which is on a vertical set of sieves receiving the
particulate material from a vibrating trough conveyor and sieved particles are
weighed by mechanically tilting the sieves and collecting; or the invention
discussed in EP0620765B1, which is related to a particle size analyzer, where
the individual sieved material is dumped on conveyer for weighing; or the
invention discussed in US4487323A, which is polygonal drum having graded
screens on each of the faces and after shaking for an appropriate time to
directly accumulate the particles on weighing machine to weigh and this is
repeated for all the grades in the drum; or the invention discussed in
US4116824A, which is an automatic sieving apparatus for wet material,
where the sieved material is collected through vacuum pump for weighing; or
the invention discussed in US4989464A, which is only a sieving process with
automatically weigh and find the particle distribution.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
The drawings refer to embodiments of the invention in which:

Fig. 1 illustrates a system for pulverized coal particles sample collection,
sieving and weighing for estimating coal particle size distribution.
Fig. 2 illustrates a stack of sieving panes placed on vibratory platform
Fig. 3 illustrates a block diagram explaining the sequence of operations
involved in estimating the distribution of pulverized coal particles sizes.
Fig. 4 illustrates a Histogram Bar Chart showing the distribution of particles
sizes with number of particles with Representative size of coal particles.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE
INVENTION
The present invention, now be described more specifically with reference to
the following specifications:
Fig. 1, shows schematic diagram of overall system with a sample collection
and segregation system (200), a coal particle conveying pipes network
system (300), a coal particle weighing system (400) and a single board
computer (500). Further, a detailed list of its embodiments including, not
limited to, an isokinetic sampler (220) for Coal Sample Collection, a plurality
of Sieving Panes (250) stacked on a vibratory base platform (260), a vacuum
pump (340) for transmitting coal particles, a network of pipes (350, 355, 360,
365), a set of valves (301, 302, 303, 304, 305, 306, 310, 315, 320, 325, 330,
335), a weighing pane (410) for collecting particles to weigh, a
communicating module (510), a data storage media (520).
Fig 2, shows details of vibratory sieving system with a stack of sieving panes
(250) with “k” individual sieving panes, pane-1 (251), pane-2 (252), pane-3
(253), pane-(k-1) (255) and pane-k (256) (251, 252,253, 254, 255, 256),
where value of “k” may change based on the interest of the ranges of coal
particle sizes. The minimum and maximum coal particle sizes and the

narrowness between two sieving sizes will decide the value of “k”, which
gives a set of ranges {R1, R2, R3, …. Rk}.
Fig 3, shows the details of computing particle size distribution from the
weights of coal particles accumulated in the sieves as following:
1. Sample collection and segregation system (200) wherein the
pulverized coal is sampled using isokinetic sampler (220) at the
pulverizer exit, where a stoichiometric mix of pulverized coal and air
being channeled towards furnace (210). Isokinetic sampler then feeds
pulverized coal into a valve controlled dispensing funnel (230).
2. On opening of funnel valve (240), the sampled pulverized coal enters
into the top sieving pane (256) of the sieving stack (250) and vibratory
platform (260) is switched “on” by the single board computer (500) to
vibrate sieving stack to create downward draft for the coal particles
and start segregating into the respective sieving panes based on
particle sizes and vibratory platform (260) is switched “off” after a
predetermined time.
The segregated coal particles are then collected through vacuum pump
(340) to weigh the particles from each of the sieving panes in the
stack (250), one after the other starting from the bottom pane (251)
while the particles are accumulated in the weighing pane. The coal
particles are transmitted from the sieving pane-1 (251) to the weighing
pane (410) by opening the valves (301, 310, 315 and 320) while all
other valves remain closed. The measured weight of coal particles
transmitted from sieving pane-1 (251) is labeled as “Q1” indicating
cumulative weight.

3. The process is repeated for all other sieving panes by operating the
valves from (301) to (306) opening them as needed during which the
valves (310, 315 and 320) are in “open” condition. To detail in generic,
the weight measured after “i” th pane is labeled as “Qi” indicating
cumulative weight of “1” to “i” panes. This process is repeated for all
“k” panes. On completion of the weighing of the accumulated coal
particles, the weighing pane (410) is evacuated using the same
vacuum pump (340).
4. All the above processes are being controlled by issuing control
instructions from the embedded single board computer (500).
5. The set of measured cumulative weights (610) of collected coal
particles i.e. {Q1, Q2, Q3, …. Qk} is used for computing weights of
coal particles segregated into each of the panes as set of weights
(630) i.e. {W1, W2, W3, …. Wk} by using a method (620) described as
following:
W1 = Q1
W2 = Q2- Q1
W3 = Q3- Q2
.
.
.
Wk = Qk - Qk-t
6. The set of computed weights (630) of coal particles collected in
individual panes i.e. {W1, W2, W3, …. Wk} are used for computing the
particle count (650) and represented as set {P1, P2, P3, …. Pk} by
using a method (640) described as following:


where, Ri is representative mean radius of the particles in “i” th pane;
p indicating the density of the coal particle for unit volume and g is the
acceleration due to gravity.
7. The set (650) that is {P1, P2, P3, …. Pk}, indicating particle counts for
corresponding set of ranges {R1, R2, R3, …. Rk} is used for plotting a
bar chart (700) to visualize distribution of coal particle counts with
respect to coal particle sizes as shown in Fig.4

WE CLAIM :
1. A system (100) for online monitoring and estimation of pulverized coal
particle size distribution, comprising:
(i) a coal sample collection and segregation device (200) having:
a) an isokinetic sampler (220) configured to receive pulverized
coal;
b) a valve (240) controlled dispensing funnel (230) coupled to
the isokinetic sampler (220), being configured to collect and
dispense a predetermined amount of the pulverized coal;
c) a stack (250) with plurality of sieving panes (251,252,…256)
(ii) a vacuum pump (340);
(iii) a set of coal transmitting pipelines (350, 355) that transmits
coal from sampling and segregation device (200) to a weighing
pane (410) and a set of evacuation pipelines (360, 365) to
evacuate coal particles after weighing cumulative weights of
coal particles;
(iv) a coal particle weighing device (400) is connected to the
vacuum pump (340) through the second pipeline for
transmitting (355) and the first pipeline for evacuating (360)
the coal particles,
(v) a weighing machine (420) to weigh all the coal particles
collected in different sieving panes; and
(vi) a single board computer (500);
Characterized in that said plurality of sieving panes (251, 252,
253, 254, 255, 256) are fixed on the vibratory platform (260)
for vibrating the plurality of sieving panes for predetermined
amount of time, and in that

- the single board computer (500) is configured to :
- control the operation of isokinetic sampler (220);
- control the operation of the valve (240) on the funnel (230);
- control the operation of the vibratory platform (260);

- control the operation of the vacuum pump (340);
- sequentially channelize coal particles from the stack of sieving
panes (250) to the weighing pane (410);
- sequentially evacuate the coal particles from the weighing
pane (410);
- compute weight of the particles segregated into each sieving
pane from a cumulative weight measured by the weighing
device (400); and
- calculate the number of particles accumulated in each of the
sieving pane based on weight of the coal particles.
2. The system as claimed in claim 1, wherein the coal transmitting and
coal evacuating pipelines (350,355,360,365) forming a coal particle
conveying pipes network (300) that couples the coal sample
collection and segregation device (200), vacuum pump (340) and
Weighing Device (400) .
3. The system as claimed in claim 1 or claim 2, comprising;
a set of valves (301, 302, 303, 304, 305, 306 and 310) placed on
the first coal transmitting pipe (350) that connects the stack of
sieving panes (250) to a vacuum pump (340) configured for
transmitting the segregated coal particles from each of the sieving
panes to a weighing device (400) through the second transmitting

pipeline (355) by a plurality of controlling valves (315 and 320);
and
a set of valves (325, 330) placed on the first evacuation pipeline
(360) from weighing device to vacuum pump (340) and a valve
(335) placed on the second evacuation pipeline (365);
4. The system (100) as claimed in claim 1, wherein the vibratory platform
(260) is controlled by said single board computer (500) to cause the
platform (260) to vibrate in directions (270).
5. The system (100) as claimed in claim 1, wherein the valve controlled
dispensing funnel (230) is provided with a valve (240) which is
configured for opening and evacuating the pulverized coal from the
valve controlled dispensing funnel (230) into a top sieving pane of said
sieving stack (250).
6. The system (100) as claimed in claim 1, wherein the coal particle
conveying pipes network (300) comprises;
said vacuum pump (340) for transmitting coal particles from source to
destination wherein said inlet pipeline (350) with valves
(301,302,303,304,305, 306 and 310) extends to the vacuum pump
(340) from the stack of sieving panes (250) wherein said outlet
pipeline (355) with valves (315, 320) extends from the vacuum pump
to the weighing pane (410); wherein the inlet pipeline (360) with
valves (325, 330) extends to the vacuum pump from the weighing

pane (410), and wherein the evacuating pipe (365) comprises at least
one valve (335).
7. The system (100) as claimed in claim 1, wherein the weighing machine
(420), is enabled to measure all the coal particles collected in the
weighing pane (410) and communicate to the single board computer
(500).