FIELD OF THE INVENTION
The present invention relates to a system for online monitoring and
estimation of pulverized Coal Particle Size Distribution, especially by
performing by rotatory sieving method. The system is enabled to sampling,
to sieving, collection of sieved coal particles for weighing, the pulverized coal
particles including estimating the number of average sized coal particles in
the predetermined ranges with respect to the weight recorded. Finally, an
overall coal particle size distribution in the range of interest is estimated and
stored into the Distribution control system (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 rotatory based
sieving method after which the particles are weighed that are accumulated in
each of the compartments concentric separators of the bottom pane attached
under the set of concentric vertical screening meshes and then weight of the
particles is correlated with number of particles with respect to the sizes.
EP0435570A1, describes a method which relates to the measurement of size
and distribution of particles and voids. More specifically, the 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 which relates 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 teaches embodiments of the invention related to
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 discloses 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, describes 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 estimating the pulverized coal particle size distribution, which is enabled
to collect coal particles sample, sieve the particles, and transmit the sieved
particles from collecting compartments through a vacuum pump to a
weighing system one after other.

A still another object of the invention is to propose a system for online
monitoring and estimating the pulverized coal particle size distribution, which
is configured to compute the weights of the particles collected in each
collecting compartments.
A further object of the invention is to propose a system for online monitoring
and estimating the pulverized coal particle size distribution, which is capable
to estimate number of coal particles collected in collecting compartments.
A still further object of the invention is to propose a system for online
monitoring and estimating the pulverized coal particle size distribution, which
is enabled to generate bar chart of the estimated coal particles size and store
the data in the plant of DCS.
SUMMARY OF THE INVENTION
The present invention relates to 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, collection of sieved particles for weighing,
analyzing the weighed particles and estimate the number of coal particles,
including distribution of coal particles based on each of the collecting

compartments of the bottom pane attached under the vertical screening
meshes. 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
concentric vertical screening meshes. Additionally, two concentric vertical
separation are also used, one for collecting the coal particles that are smaller
than the “X1” and another concentric vertical separation for collecting larger
than the “X2” respectively; making it “K” panes with graduated screening
mesh sizes. However, the outer most concentric vertical separation does not
have screening mesh.
The present invention relates to a system for monitoring and estimating the
distribution of pulverized coal particles as compared to the admitted prior art
EP0435570A1, which relates to the measurement of size by chord length and
distribution of latex particles and voids in paint industry; US7177487B2, which
is applicable for small particles used in pharmaceutical industry such as those
that are less than 1 um in size by scanning electron photomicrographs; or
US2007/0229823A1, which relates 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 US2010/0169038A1, which is on processes employing
algorithms for calculating particle size distribution of different particle shapes

from chord length distributions; or US2014/0320639A1, which discloses a
system for estimating size distribution and concentration of aerosols in an
atmospheric region; or CN102890050B, which is a calibration method for
laser coal particles size distribution by an offline sieving analysis; or
US5059310A, which teaches 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 EP0620765B1, relating to
a particle size analyzer, where the individual sieved material is dumped on
conveyer for weighing; or US4487323A, which shows a 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
repeatedly weigh for all the grades in the drum; or US4116824A, which is an
automatic sieving apparatus for wet material, where the sieved material is
collected through vacuum pump for weighing; or even the prior art
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 set of concentric vertical screening meshes with a
collecting compartmentalized pane attached at the bottom
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 shall 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 concentric vertical screening meshes (250) with a collecting
compartmentalized pane (290) rotated by a motor (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, 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 rotatory sieving system with a set of concentric vertical
screening meshes (250) with “k” individual vertical screening meshes, vertical
screening mesh-1 (251), vertical screening mesh -2 (252), vertical screening
mesh -3 (253), 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 compartmentalized pane 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 inner most sieving mesh (254) of concentric vertical screening
meshes (250) with a collecting compartmentalized pane (290) and
motor (260) is switched “on” by the single board computer (500) to
rotate the concentric vertical screening meshes (250) to create a
radially outward draft for the coal particles and start segregating into

the respective compartments based on particle sizes and motor (260)
is switched “off” after a predetermined time.
The segregated coal particles are then transmitted through vacuum
pump (340) to weigh the particles from each of the compartments of
compartmentalized pane (290), one after the other starting from the
outer most sieving mesh (251) while the particles are accumulated in
the weighing pane. The coal particles are transmitted from the
screening mesh-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 the screening
mesh-1 (251) is labeled as “Q1” indicating cumulative weight.
3. The process is repeated for all other screening meshes by operating
the valves from (301) to (304) 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 screening mesh is labeled as
“Qi” indicating cumulative weight of “1” to “i” screening mesh. This
process is repeated for all “k” screening meshes. 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 compartments of
compartmentalized pane as set of weights (630) i.e. {W1, W2, W3, ….
Wk} by using a method (620) described as following:

6. The set of computed weights (630) of coal particles collected in
individual compartments of compartmentalized pane 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
compartment of compartmentalized 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:
a) - a coal sample collection and segregation device (200) having:
- an isokinetic sampler (220) configured to receive pulverized
coal,
- a valve (240) controlled dispensing funnel (230) coupled to the
isokinetic sampler (220), being configured to collect and
dispense a predetermined amount of pulverized coal,
- A MOTOR (260);
- a set of concentric vertical screening meshes (250) comprising a
plurality of vertical screening meshes (251, 252, 253) mounted
on a concentric compartmentalized pane (290) and coupled to
the motor (260) rotatable for a predetermined amount of time
to segregate the pulverized coal particles into the respective
sized concentric compartments;
b) - a coal particle conveying tubular network (300) coupled to the
coal sample collection and segregation device (200), and a
weighing device (400) and having:
- a vacuum pump (340),
- a set of coal transmitting pipelines (350, 355) that transmits
coal from said sampling and segregation device (200) to a
weighing pane (410) and a set of evacuation pipelines (360,
365) to evacuate coal particles after completing the weighing of
cumulative amount of coal particles collected in each of the
compartments in the concentric compartmentalized pane (290),

- a first set of valves (301, 302, 303, 304, 310) placed on the
first transmitting pipe (350) that connects said concentric
compartmentalized pane (290) to the vacuum pump (340)
configured to transmit the segregate coal particles from
each of the concentric compartments to the weighing device
(400) through said second transmitting pipeline (355) by a
plurality of controlling valves (315,320), and
- a second set of valves (325, 330) placed on the first evacuation
pipeline (360) from the weighing device (400) to the vacuum
pump (340) and a valve (335) placed on the second evacuation
pipeline (365);
c) - the coal particle weighing device (400) connected to the
vacuum pump (340) through the second transmitting pipeline
(355) and the second evaluation pipeline (360) the coal
particles weighing device having:
- said weighing pane (410) that accumulates and weighs all the
coal particles collected in different concentric compartments
(290),
d) a weighing machine (420) to weigh said accumulated coal
particles,
e) a single board computer (500) that controls the coal sample
collection and segregation device (200), coal particle conveying
pipes network (300) and coal particle weighing device (400).
2. The system (100) as claimed in claim 1, wherein the collection and
segregation device (200) is coupled to the motor (260) rotatable for a
predetermined amount of time.

3. The system (100) as claimed in claim 1, wherein the motor (260) is
controlled by the embedded single board computer (500) to rotate in a
direction (270).
4. The system (100) as claimed in claim 1, wherein said valve controlled
dispensing funnel (230) is provided with the valve (240) which is
configured for opening and evacuating the valve controlled dispensing
funnel (230) into the inner most vertical screening mesh of the
concentric vertical screening meshes (250).
5. The system (100) as claimed in claim 1, wherein :
the first transmitting pipeline (350) with valves (301,302,303,304,
310) connecting the vacuum pump (340) with the collecting
compartmentalized pane (290);
the second transmitting pipeline (355) with valves (315, 320)
connecting the vacuum pump (340) with the weighing pane (410);
the first evaluating pipeline (360) with valves (325, 330) connecting
the vacuum pump (340) with the weighing pane (410); and
the second evacuating pipe (365) with a valve (335) from the vacuum
pump (340) .
6. The system (100) as claimed in claim 1, wherein :
all the coal particles are collected in the weighing pane (410) to weigh
cumulatively; and

the weight of the coal particles is measured in the weighing machine
(420) and communicated to the single board computer (500).
7. The system (100) as claimed in claim 1, wherein the single board
computer (500) for controlling, computing, data processing and data
storing, is configured to :
- control the operation of isokinetic sampler (220);
- control the operation of valve (240) on the funnel (230);
- control the operation of the motor (260);
- control the operation of vacuum pump (340);
- sequentially control the operation of the valves (301, 302, 303,
304, 310, 315 and 320) for channelizing coal particles from the
set of concentric vertical screening meshes (250) to the
weighing pane (410);
- sequentially control the operation of the valves (325, 330 and
335) for evacuating the coal particles from the weighing pane
(410);
- compute weight of the particles segregated into each of the
compartments in the concentric compartmentalized pane (290)
using cumulative weightS measured by the weighing device
(400); and

- compute number of particles accumulated into each of the
compartments in the concentric compartmentalized pane (290)
based on weight of the coal particles.