Title of Invention

A PROCESS FOR REDUCING VARIATION IN DISTRIBUTION OF COAL WATER SLURRY

Abstract The present invention discloses a process for reducing variation in distribution of coal water slurry in coal preparation plants through the distributor, comprising the steps of providing a cylindrical insert at the center of the distributor lower chamber, providing tangential water inlets in the upper chamber, feeding cola from a feeder provided at the top of the distributor for mixing with water to form coal-water slurry and directing the coal slurry to a set of outlet ports using said cylindrical insert for uniform distribution of coal water slurry.
Full Text FIELD OF APPLICATION
This invention relates to a process for reducing variation in distribution of coal
water slurry through the distributor.
BACKGROUND OF THE INVENTION
The development of large scale coal preparation plants led to the requirement
for the subdivision of solid / liquid slurries at a number of stages. The sub-
division of slurry feed to a number of unit operations in parallel (e.g., cyclones,
spirals and flotation units) is usually accomplished using multi-port distributors,
which can have a wide range of shape and dimensions. A typical sputnik multi-
port distributor comprises two separated parts, the upper chamber and the lower
chamber. The upper chamber is mainly used to enhance the mixing process
through the vortex motion, while the lower chamber directs the coal slurry form
the top to the outlets at the bottom. The distributor insert is designed in the
form of a frustum to push the coal slurry into these outlets.

Desirable performance of the distributor is unbiased coal slurry output from all in
the outlets. However biased distributors have been reported from coal
preparation plants. Since the distributor is the first stage of the coal preparation
process, the biased distributions have serious effect on the overall performance
of the coal preparation plant, leading to a serious economic loss. The biased sub-
division of slurry fed to a number of unit operating in parallel would cause each
unit to operate under different separation density, volumetric flow-rate, feed
pressure and feed concentration leading to reduced operating efficiencies in
mineral and coal preparation plants.
Thus, there was a need for obtaining unbiased coal slurry output form all the
outlets of the distributor.
SUMMARY OF THE INVENTION
Therefore, the main object of the present invention is to provide a process for
reducing variation in distribution of coal water slurry by modifying feed
distribution for feed to the coal preparation.
Another object of the invention is to reduce the bias or non-uniformity in
distribution.

A further object of this invention is to provide a process for reducing variation in
distribution of coal water slurry for the modified distributor that would reduce the
economic losses due to biased distribution of feed to coal preparation plants and
which can be practiced without difficulty.
These and other objects of the present invention are achieved by providing a
cylindrical insert above the frustum at the center of the distributor in its lower
chamber. The cylindrical insert can be extended upto the tangential water inlets
provided in the upper chamber.
This arrangement is able to arrest formulation of low velocity zones inside the
distributor causing non-uniform distribution of coal particles from the distributor
outlets.
In the present invention four tangential water inlets are provided along with an
inverted "V" shaped feeder to allow the feed to fall peripherally in the distributor
through an annular ring.
This arrangement will further reduce chances of formation of dead zones inside
the distributor and thereby causing non-uniform distribution of coal through the
distributor outlets.

Thus the present invention provides a process for reducing variation in
distribution of coal water slurry in coal preparation plants through the distributor,
comprising the steps of providing a cylindrical insert at the center of the
distributor lower chamber; providing tangential water inlets in the upper
chamber; feeding coal from a feeder provided at the top of the distributor for
mixing with water to form coal-water slurry; and directing the coal slurry to a set
of outlet ports using said cylindrical insert for uniform distribution of coal water
slurry.
The nature of the invention, its objects and further advantages residing in the
same wilt be apparent from the following description made with reference to the
non-limiting accompanying drawings.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
The invention can now be deserted in detail with the help of the figures of the
accompanying drawing in which:
Figure 1 shows the existing design of the sputnik distributor
in a coal washery.
Figure 2 shows the dead zone in the existing design of the
distributor that does not participate in the mixing process.

Figures 3(a)
(b), 3(c)
and 3(d) show the reporting of different size of coal
particles through different ports of the distributor.
Figure 4 shows the velocity contours in the design of the
distributor of the present invention
Figure 5 shows the design of the distributor of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
A typical sputnik multi-port distributor as shown in Figure 1. The distributor
comprises an upper chamber 2 used for feeding coal through a feeder 3 and for
enhancing the mixing of coal, with water fed through tangential water inlets 4
using the vortex motion. The distributor is also provided with a lower chamber
for directing the coal slurry from the top to the outlet ports 6. A distributor
insert 7 is provided, in the form of a frustum for pushing the coal slurry into
onlet ports 6.

As described earlier, there have been reports of biased or non-uniforms
distribution of coal slurry from the distributor outlets. The problem was studied
and the variation of solids flow through different outlets and the variation in size
distribution were calculated using two indices the coal split ratio and the
variation index. To calculate the variation index, the difference between the
maximum percentage and minimum weight percentage of particles of the
particular size reporting from the outlets are added. The coal split ratio is
calculated as the ratio of maximum solids flow in any outlet to minimum solids
flow in another outlet in g / min.
As shown in Figure 2, in CFD simulations there exists a low velocity zone at the
center to the distributor, which is a dead zone and which does not take part in
mixing activity. The major bias in size distribution is observed in the distribution
of coarse coal i.e. + 10 mm (in outlets 1 and 5 - outlets directly below the water
inlet) since their trajectories were mostly affected by gravitational force. Hence,
once caught into the water flow the particles entered the central low velocity
zone and went down the port below as shown in Figures 3 (a), 3 (b), 3 (c) and
(d). The path of fine particles followed the water flow and they got discharged
with water. They were greatly influenced by turbulence.
It was noticed that though the water splits were uniform, there was a significant
variation in particle distribution. Therefore, alternate designs had to be explored.

The non-uniform distribution of coal particles from the outlets could be expected
because of the existence of tow velocity regions. Generally the particles are
likely to deposit in the low velocity region. In order to arrest these core low
velocity regions, various new designs were explored like redesigning the insert.
As shown in Figure 5 a cylindrical insert 17 is used in the present invention. This
insert 17 can be placed over the frustum 17' of the lower chamber 15 of the
distributor 10 of the present invention.
The design of a combination of the cylinder and the frustum was able to arrest
the formation of low velocity zone inside the distributor 10 as shown in Figure 4.
The cylindrical insert 17 can be extended upto the top of tangential water inlets
14.
An inverted V feeder 13' is provided below a coal feeder 13 for distributing the
coal in an annular ring in the distributor 10 which allows the feed to fall
peripherally.
It was observed that letting the feed fall peripherally in the distributor further
reduced the chance of formation of the dead zone. The summary of the test
results with modified inserts and feeding position are shown in Table 1.

Table 1: Result showing the value* of (I) variation index and (II) coal split
ratio in the present and modified design of the distributor.

The least variation index and the coal split ratio were obtained at the optimum
conditions (Test 12 in Table 1).
Four water inlets 14 with equal water flow in two opposites inlets were used. A
cylindrical insert 17 was provided above a frustum 17 as a combination central
insert. Symmetrically arranged outlets ports 16 were used. A lower turbulence,
a higher volume percentage of solids (20 %) and the particles falling in an
annular ring in the distributor 10 were used. As can be seen, the new insert
design and distribution in an annular ring have resulted in better distribution of
coal particles at higher volume percentage of solids. The new design of the
distributor 10 of the present invention is shown in Figure 5.
In the present invention the economic losses to variation in coal distributor are
reduced. The composite yield from the dense media cyclone increases as a
result of addition of the viscosity modifier.

WE CLAIM
1. A process for reducing variation in distribution of coal water slurry in coal
preparation plants through the distributor, comprising the steps of:
- providing a cylindrical insert at the center of the distributor lower
chamber;
- providing tangential water inlets in the upper chamber;
- feeding coal from a feeder provided at the top of the distributor for
mixing with water to form coal-water slurry; and
- directing the coal slurry to a set of outlet ports using said cylindrical
insert for uniform distribution of coal water slurry.

2. The process as claimed in claim 1, wherein said cylindrical insert is
provided above the frustum at the center of the distributor lower
chamber.
3. The process as claimed in claim 2, wherein said cylindrical insert expands
upto the top of the tangential water inlets.
4. The process as claimed in claim 1, wherein four tangential water inlets are
provided for inlet of equal water flow through two opposite inlets.

5. The process as claimed in claim 1, wherein said feeder is an inverted "V"
type feeder for distributing the coal in an annular ring in the distributor for
allowing the feed to fall peripherally.
6. The process as claimed in claim 1, wherein said outlet ports are
symmetrically arranged at the bottom of the lower chamber.
7. A process for reducing variation in distribution of coal water slurry in coal
preparation plants through the distributor substantially as herein described
and illustrated in the accompanying drawings.

The present invention discloses a process for reducing variation in
distribution of coal water slurry in coal preparation plants through the
distributor, comprising the steps of providing a cylindrical insert at
the center of the distributor lower chamber, providing tangential
water inlets in the upper chamber, feeding cola from a feeder
provided at the top of the distributor for mixing with water to form
coal-water slurry and directing the coal slurry to a set of outlet ports
using said cylindrical insert for uniform distribution of coal water
slurry.

Documents:

15-kol-2005-granted-abstract.pdf

15-kol-2005-granted-claims.pdf

15-kol-2005-granted-correspondence.pdf

15-kol-2005-granted-description (complete).pdf

15-kol-2005-granted-drawings.pdf

15-kol-2005-granted-examination report.pdf

15-kol-2005-granted-form 1.pdf

15-kol-2005-granted-form 13.pdf

15-kol-2005-granted-form 18.pdf

15-kol-2005-granted-form 2.pdf

15-kol-2005-granted-form 3.pdf

15-kol-2005-granted-form 5.pdf

15-kol-2005-granted-gpa.pdf

15-kol-2005-granted-reply to examination report.pdf

15-kol-2005-granted-specification.pdf


Patent Number 234612
Indian Patent Application Number 15/KOL/2005
PG Journal Number 24/2009
Publication Date 12-Jun-2009
Grant Date 09-Jun-2009
Date of Filing 17-Jan-2005
Name of Patentee TATA STEEL LIMITED
Applicant Address RESEARCH AND DEVELOPMENT AND SCIENTIFIC SERVICES DIVISION, JAMSHEDPUR
Inventors:
# Inventor's Name Inventor's Address
1 DUTTA ATANU TATA STEEL LIMITED RESEARCH AND DEVELOPMENT AND SCIENTIFIC SERVICES DIVISION, JAMSHEDPUR 831 001
2 MISRA ARUN TATA STEEL LIMITED RESEARCH AND DEVELOPMENT AND SCIENTIFIC SERVICES DIVISION, JAMSHEDPUR 831 001
3 SRIPRIYA R TATA STEEL LIMITED RESEARCH AND DEVELOPMENT AND SCIENTIFIC SERVICES DIVISION, JAMSHEDPUR 831 001
4 NARASIMHA M TATA STEEL LIMITED RESEARCH AND DEVELOPMENT AND SCIENTIFIC SERVICES DIVISION, JAMSHEDPUR 831 001
5 DUTTA ATANU TATA STEEL LIMITED RESEARCH AND DEVELOPMENT AND SCIENTIFIC SERVICES DIVISION, JAMSHEDPUR 831 001
6 MISRA ARUN TATA STEEL LIMITED RESEARCH AND DEVELOPMENT AND SCIENTIFIC SERVICES DIVISION, JAMSHEDPUR 831 001
7 NARASIMHA M TATA STEEL LIMITED RESEARCH AND DEVELOPMENT AND SCIENTIFIC SERVICES DIVISION, JAMSHEDPUR 831 001
8 SRIPRIYA R TATA STEEL LIMITED RESEARCH AND DEVELOPMENT AND SCIENTIFIC SERVICES DIVISION, JAMSHEDPUR 831 001
PCT International Classification Number F23K 3/00
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 NA