Title of Invention

A METHOD FOR SUPPRESSED AIR CORE IN A CYLONE AND A CYLONE WITH SUPPRESSED AIR CORE

Abstract Accordingly, there is provided a method for suppressing air core in a cyclone and performing a particle separation test in a cyclone having a suppressed air core. The method comprising: •connecting a cyclone to a water /slurry inlet through which water /slurry is introduced into the cyclone at the desired flow rate, the flow rate being measured by adapting a rotameter, •pumping the slurry/water from a slurry tank having provisions for bypass, •providing control valves at the overflow and the underflow outlets of the cyclone to vary the flow rates, •providing pressure tapping at the inlet, overflow and underflow, •connecting the pressure tapping to a series of manometers which can measure the pressure drop across the cyclone, •setting the inlet flow rate to the desired value, and varying the underflow/overflow rate in a such a way so as to get a good air core, •measuring the inlet and the underflow rate, •stopping the flow to the cyclone, •making an insertion in the centre/bottom of the cyclone body for inserting a rod,
Full Text -2-FIELD OF INVENTION
The present invention generally relates to hydrocyclones, in particular dense medium cyclones for carrying-out particle separation tests. More particularly, the invention relates to a method of suppressing air core in cyclones . The invention further relates to method and device for conducting separation of particles in the cyclone having suppressed air core.
BACKGROUND OF INVENTION
Hydrocyclone is an equipment that is used to separate particles based on size and it uses water as the media for separating particles into different size ranges.
The dense-medium cyclone, on the other hand is an equipment that operates on the principle of gravity separation. Pure coal (specific gravity 1.3) and pure ash (>2) have different specific gravities. When the coal and ash particles are introduced into a medium whose specific gravity is intermediate to that of coal and ash, the lighter coal particles would float, and the heavier ash particles would sink. In a dense medium cyclone, the medium for separation is fine maanetite particles suspended in water.

-3-
A conventional cyclone as described hereinabove, is generally having a cylindro-conical shape (fig 1). The magnetite slurry along with coal is introduced tangentially into the equipment. The slurry as it descends down, the cyclone forms a free vortex (1) in the periphery with a forced vortex (2) at the centre. The particles that are introduced are forced to separate in the radial direction, with the heavier ash particles thrown towards the periphery, and discharging through the underflow (3), while the lighter coal particles are carried upward along with the forced vortex (2), to discharge through the overflow (4). The forced vortex (2) envelopes an air core (5) which is created due to a low pressure zone, and is created at the centre. The air core (5) is sucked in through the underflow (3) and extends all along the length of the cyclone uptill the overflow (4). However, experimentations have established that separation efficiency of particles in a cyclone is substantially improved if the separation is carried-out with a cyclone having suppressed air core. A thorough search on published literature and patents reveals that although standard method for separation of particles in conventional cyclones is known, however they poses low efficiency and error-prove results. On the other hand, there is no method or device available for carrying out separation of particles in conventional

-4-
cyclones in which the air core has been suppressed to substantially improve the efficiency of the method including the device.
OBJECTS OF THE INVENTION
It is therefore an object of the invention to propose a method of suppressing air core in a conventional cyclone which is simple, cost-effective and easy to perform.
Another object of the invention is to propose a method of suppressing air core in a conventional cyclone which is reproducible
A further object of the invention is to propose a method of carrying out particle separation tests in a cyclone having suppressed air core which is simple,cost-effective, and easy to perform.
A still further object of the invention is to propose a method of carrying out particle separation tests in a cyclone having suppressed air core which is reproducible and user-friendly.

-5-SUMMARY OF THE INVENTION
Accordingly, there is provided a method for suppressing air core in a cyclone and performing a particle separation test in a cyclone having a suppressed air core. The method comprising:
• connecting a cyclone to a water /slurry inlet through which
water /slurry is introduced into the cyclone at the desired flow
rate, the flow rate being measured by adapting a rotameter,
• pumping the slurry/water from a slurry tank having provisions
for bypass,
• providing control valves at the overflow and the underflow
outlets of the cyclone to vary the flow rates,
• providing pressure tapping at the inlet, overflow and underflow,
• connecting the pressure tapping to a series of manometers
which can measure the pressure drop across the cyclone,
• setting the inlet flow rate to the desired value, and varying the
underflow/overflow rate in a such a way so as to get a good air
core,
• measuring the inlet and the underflow rate,
• stopping the flow to the cyclone,
• making an insertion in the centre/bottom of the cyclone body
for inserting a rod,

-6-
• inserting the rod at a height where the air core would
disappear,
• continuing the insertion of the rod till the centre of the cyclone
if the provision is made for insertion at the centre of the
cyclone body,
• inserting, the rod till one fourth of the height from the bottom if
the rod is inserted from the bottom using clamps placed below
and outside the bottom of the cyclone,
• selecting the rod for insertion with 3-4mm in dia,
• varying the flow rates till such-time a good air core would be
formed extending from top to the bottom of the cyclone.
• introducing density tracers/coal particles,
• collecting the particles/slurry coming from the overflow and the
underflow
• weighing the coal particles from the coal slurry coming from the
overflow and underflow after drying,
• carrying-out sink-float tests to find out the percentage of coal
particles reporting to the overflow and underflow.
• determining the percentage of lighter and heavier particles
reporting to the overflow and underflow, if the particles are
density tracers,

-7-
• calculating the separation efficiency as the percentage of lighter
particles of the feed reporting to the overflow. The standard sink-float tests adaptable to the present invention can be described as under:
The sink-float tests are a series of tests done to determine the yields obtainable under ideal conditions at different levels of ash when coal is washed. It is a test in which the coal is put initially in an organic liquid of specific gravity 1.3. The coal is allowed sufficient time so that a clear distinction between the floating coal and the sinking coal is visible. The coal that floats in the liquid is called the "float" and the sink the "sink". The float and the sink are weighed and are analysed for ash content. The rest of the sink is then put in a liquid of higher specific gravity, say 1.4. This is continued until a specific gravity of 2.0 is reached. The weights and ash content of the coal thus collected are used to plot curves from which the yield of clean coal obtainable at a particular ash content can be determined.
The method by which a sink-float test is carried-out, and, the principle of which is being adapted in the present invention can further be illustrated in reference to a conventional dense-medium cyclone.

-8-
A dense-medium cyclone is illustrated in figure 1. The dense-medium cyclone (8) is arranged in closed circuit with a slurry tank (6), a slurry pump (7) and a by-pass line (9) as shown in Fig. 2. The cyclone (8) is fitted directly above the slurry tank (6) so that when the samples are not collected, the overflow (10) and underflow (11) streams are discharged directly into the tank (6). A by-pass valve (9a) in the line (9) is used for adjusting the feed rate of the slurry to the cyclone (8) and the pressure at the feed inlet (12) of the cyclone (8). The recirculation of the slurry and the agitation due to provision of a heavy duty stirrer (13) in the tank (6) are sufficient to keep the slurry in the tank (6) in uniform suspension. The cyclone (8) is provided with facilities to change the spigot and vortex finder (not shown). Before the start of an experiment, the required spigot and vortex finder are inserted in the cyclone (8). Then, keeping the heavy-duty stirrer (13) running, requisite quantities of water, magnetite and coal are added to the slurry tank (6). The magnetite to coal ratio maintained in all the experiments is 4:1 by weight. The slurry is pumped into the cyclone (8) keeping the bypass valve (9a) fully open and then this valve (9a) is adjusted to obtain the required pressure at the inlet (12) of the cyclone (8). The system is then allowed to run for some minutes until a steady state is attained. Once the steady

-9-
state is reached, the overflow and underflow slurry samples (10,1?) are collected for a known period and the weights of these samples (10,11) are noted separately.
The coal is separated from the slurry samples (10,11) collected from the overflow and underflow (10,11) by draining over a 100 mesh sieve with a water spray (14). The magnetite along with water passed through the screen while the coal particles are retained over the screen. The magnetite in each sample is recovered from the slurry by filtration. The coal and magnetite samples thus recovered are dried and weighed separately. The overflow and underflow magnetite samples (10,11) are size analyzed. The coal samples recovered are subjected to sink float analysis at different specific gravities. The flow rates of slurry, coal, magnetite and water in the overflow and underflow streams (10,11) are calculated. The size analyses are carried out to estimate the degradation of coal during experimentation, which has been found to be negligible. This procedure is followed in all the experiments conducted at different levels of design and operating variables.

-10-BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Figure-1 - Shows a schematic of a conventional cyclone,
Figure-2- A device for conducting seperation of particles in a
conventional cyclone according to prior art,
Figure-3- A device for conducting separation of particles in a cyclone
with suppressed air core according to the present invention.
Figure-4- Shows a method for suppression of air core from centre
according to present invention
DETAIL DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION
Figure-3 illustrates as to how the particle separation test is carried-out in a cyclone having suppressed air core.
The cyclone ( c) is run with water to determine the conditions when a full air core will be formed. Once the air core is formed, the overflow and the underflow rates (10,11) and the pressure difference from the manometer are noted down. The inlet water (12) is then stopped. A rod (19) is then inserted in the cyclone ( c) (from

-11-the top/sides/bottom, whichever way the provision is made) in such a way so as to suppress the air core. The water flow is then started and then the overflow and underflow rates (10,11) are adjusted in a range where a good air core extending from top to bottom would be formed. The density tracers of different specific gravities (in this case 108 particles are introduced; and the number of lighter and denser particles, coming out of the overflow and underflow (10,11) are counted. The separation efficiency is taken as % of lighter material of feed reporting to overflow (10).
Fig 3 further shows the details as to how the provision for inserting the rod at the centre for suppressing the air core is created. The cyclone assembly ( c) is made of Perspex. In practice the cyclone can be made of the standard material like Polyurethane/ any other material of which industrial cyclones are made. The inlet (12) and the outlet ports (16) are all M.S tubes; In practice, the outlet ports (16) can be made of Perspex or of the same material of which the cyclone ( c ) is made
The rest of the piping are all M.S. The insertion rod (19) is a M.S tub. A U tube manometer assembly (17) is made of Perspex. The cyclone assembly is made of non-reactive material and houses a means (20) for inserting the rod (19) that can suppress the air core.

-12-
The invention is an integral/ core part of the cyclone assembly. The
cyclone assembly is used generally for studying the classification
efficiency or the separation efficiency of particles. The cyclone
assembly consists of the following parts serving the respective
functions.
The cyclone body can be conical or cylindro-conical in a shape and
has an inlet (12). The water or slurry is introduced into the cyclone (
c ) through the inlet (12). The overflow and the underflow outlets
(10,11) remove the slurry and the particles from the cyclone ( c )
after separation.
The water/slurry pipe lines (L) through which slurry or water flows
and are connected to the outlets (16) and inlets (12) of the cyclone
(c).
The pressure tappings connect the outlets (16) to the U tube
manometer (17) and are used to measure the pressure drop.
The U tube manometer (17) are manometer tubes filled with mercury
and are required for the measurement of pressure difference.
A rotometer (18) is provided for measuring inlet water flow rate, and
a slurry tank (6) is flowably connected to the cyclone (c ) via tubular
network.

-13-WE CLAIM:
1. A method for suppressing air core in a cyclone to improve its
particles separation efficiency, comprising the steps of:-
- providing a cyclone assembly ( c ) having an inlet port
(12) and an outlet port (16);
- providing means (20) on the cyclone body for inserting a
rod (19) capable of suppressing the air core;
- inserting the rod (19) to reach the centre of the cyclone
body when the provisioning means (20) being configured
at a height in the central location;
- alternatively inserting the rod (19) till one fourth of the
height from the bottom when the provisioning means
(20) being configured at the bottom of the cyclone (c ).
2. A method for separating particles in a cyclone with suppressed
air core, comprising the steps of:
- connecting a cyclone to a water /slurry inlet through which water /slurry is introduced into the cyclone at a desired flow rate, the flow rate being measured by adapting a rotameter;

-14-
- pumping the slurry/water from a slurry tank having a provision
for bypass;
- providing atleast one control valve at the overflow and the
underflow outlets of the cyclone to vary the flow rates;
- providing pressure tappings at the inlet, overflow and underflow;
- connecting the pressure tappings to a series of manometers
which can measure the pressure drop across the cyclone;
- setting the inlet flow rate to the desired value, and varying the
underflow/overflow rate in such a way so as to develop a
substantially good air core;
- measuring the inlet and the underflow rate,
- stopping the flow to the cyclone;
- introducing density tracers/coal particles;
- collecting the particles/slurry coming from the overflow and the
underflow ;
- weighing the coal particles from the coal slurry coming from the
overflow and underflow after drying;
- determining the percentage of coal particles reporting to the
overflow and underflow by adapting sink float test;
- determining the percentage of lighter and heavier particles
reporting to the overflow and underflow, if the particles are
density tracers; and

-15-
- calculating the separation efficiency as the percentage of lighter particles of the feed reporting to the overflow.
3. A cyclone with suppressed air-core, comprising:
- a cyclone body made of Perspex or of any material
constituting a known cyclone body;
- an inlet port (12) and an outlet port (16) configured at
the top and bottom of the cyclone body, the inlet port
(12) allowing delivery of water or slurry into the cycle, the
outlet port (16) being connectable to an U-tube
manometer (17);
- one each overflow and underflow outlets (10,11)
provided on the cyclone body to remove the slurry and
particles after separation;
- a provisioning means (20) housed on the cyclone body
for allowing insertion and fixing of a rod (19) either
through the bottom or at the centre of the cyclone body
for suppressing air core.
4. A method for suppressing air core in a cyclone to improve its
particles separation efficiency as substantially described and
illustrated herein with reference to the accompanying drawings.

-16-
5. A method for separating particles in a cyclone with suppressed
air core as substantially described and illustrated herein with
reference to the accompanying drawings.
6. A cyclone with suppressed air-core, as substantially described
and illustrated herein with reference to the accompanying
drawings.
Accordingly, there is provided a method for suppressing air core in a cyclone and performing a particle separation test in a cyclone having a suppressed air core. The method comprising:
Accordingly, there is provided a method for suppressing air core in a cyclone and performing a particle separation test in a cyclone having a suppressed air core. The method comprising:
• connecting a cyclone to a water /slurry inlet through which
water /slurry is introduced into the cyclone at the desired flow
rate, the flow rate being measured by adapting a rotameter,
• pumping the slurry/water from a slurry tank having provisions
for bypass,
• providing control valves at the overflow and the underflow
outlets of the cyclone to vary the flow rates,
• providing pressure tapping at the inlet, overflow and underflow,
• connecting the pressure tapping to a series of manometers
which can measure the pressure drop across the cyclone,
• setting the inlet flow rate to the desired value, and varying the
underflow/overflow rate in a such a way so as to get a good air
core,
• measuring the inlet and the underflow rate,
• stopping the flow to the cyclone,
• making an insertion in the centre/bottom of the cyclone body
for inserting a rod,

-6-
• inserting the rod at a height where the air core would
disappear,
• continuing the insertion of the rod till the centre of the cyclone
if the provision is made for insertion at the centre of the
cycione body,
• inserting, the rod till one fourth of the height from the bottom if
the rod is inserted from the bottom using clamps placed below
and outside the bottom of the cyclone,
• selecting the rod for insertion with 3-4mm in dia,
• varying the flow rates till such-time a good air core would be
formed extending from top to the bottom of the cyclone.
• introducing density tracers/coal particles,
• collecting the particles/slurry coming from the overflow and the
underflow
• weighing the coal particles from the coal slurry coming from the
overflow and underflow after drying,
• carrying-out sink-float tests to find out the percentage of coal
particles reporting to the overflow and underflow.
• determining the percentage of lighter and heavier particles
reporting to the overflow and underflow, if the particles are
density tracers,

-7-
calculating the separation efficiency as the percentage of lighter
particles of the feed reporting to the overflow. The standard sink-float tests adaptable to the present invention can be described as under:
The sink-float tests are a series of tests done to determine the yields obtainable under ideal conditions at different levels of ash when coal is washed. It is a test in which the coal is put initially in an organic liquid of specific gravity 1.3. The coal is allowed sufficient time so that a clear distinction between the floating coal and the sinking coal is visible. The coal that floats in the liquid is called the "float" and the sink the "sink". The float and the sink are weighed and are analysed for ash content. The rest of the sink is then put in a liquid of higher specific gravity, say 1.4. This is continued until a specific gravity of 2.0 is reached. The weights and ash content of the coal thus collected are used to plot curves from which the yield of clean coal obtainable at a particular ash content can be determined.
The method by which a sink-float test is carried-out, and, the principle of which is being adapted in the present invention can further be illustrated in reference to a conventional dense-medium cyclone.

Documents:

01130-kol-2006 abstract.pdf

01130-kol-2006-asignment.pdf

01130-kol-2006-claims.pdf

01130-kol-2006-correspondence others.pdf

01130-kol-2006-correspondence-1.1.pdf

01130-kol-2006-description(complete).pdf

01130-kol-2006-drawings.pdf

01130-kol-2006-form-1.pdf

01130-kol-2006-form-2.pdf

01130-kol-2006-form-3.pdf

01130-kol-2006-form-9.pdf

1130-KOL-2006-ABSTRACT 1.1.pdf

1130-kol-2006-abstract 1.2.pdf

1130-kol-2006-amanded claims.pdf

1130-kol-2006-amanded pages of specification.pdf

1130-KOL-2006-CANCELLED PAGES.pdf

1130-KOL-2006-CLAIMS 1.1.pdf

1130-KOL-2006-CORRESPONDENCE-1.1.pdf

1130-KOL-2006-CORRESPONDENCE.1.3.pdf

1130-KOL-2006-DESCRIPTION (COMPLETE) 1.1.pdf

1130-KOL-2006-DRAWINGS 1.1.pdf

1130-KOL-2006-EXAMINATION REPORT.1.3.pdf

1130-KOL-2006-FORM 1-1.1.pdf

1130-kol-2006-form 1-1.2.pdf

1130-KOL-2006-FORM 1.1.1.pdf

1130-KOL-2006-FORM 13.1.3.pdf

1130-KOL-2006-FORM 13.pdf

1130-KOL-2006-FORM 18.1.3.pdf

1130-kol-2006-form 2-1.2.pdf

1130-KOL-2006-FORM 2.1.1.pdf

1130-KOL-2006-FORM 3.1.3.pdf

1130-KOL-2006-FORM 9.1.3.pdf

1130-KOL-2006-GPA.1.3.pdf

1130-KOL-2006-GRANTED-ABSTRACT.pdf

1130-KOL-2006-GRANTED-CLAIMS.pdf

1130-KOL-2006-GRANTED-DESCRIPTION (COMPLETE).pdf

1130-KOL-2006-GRANTED-DRAWINGS.pdf

1130-KOL-2006-GRANTED-FORM 1.pdf

1130-KOL-2006-GRANTED-FORM 2.pdf

1130-KOL-2006-GRANTED-LETTER PATENT.pdf

1130-KOL-2006-GRANTED-SPECIFICATION.pdf

1130-KOL-2006-OTHERS.1.3.pdf

1130-KOL-2006-PETITION UNDER RULE 137.pdf

1130-KOL-2006-REPLY TO EXAMINATION REPORT.1.3.pdf

1130-KOL-2006-REPLY TO EXAMINATION REPORT.pdf

abstract-01130-kol-2006.jpg


Patent Number 248849
Indian Patent Application Number 1130/KOL/2006
PG Journal Number 35/2011
Publication Date 02-Sep-2011
Grant Date 30-Aug-2011
Date of Filing 26-Oct-2006
Name of Patentee TATA STEEL LIMITED
Applicant Address Jamshedpur-831001, India
Inventors:
# Inventor's Name Inventor's Address
1 R. SRIPRIYA R& D Tata Steel Limited, Jamshedpur-831001
2 B. MEIKAP R&D Tata Steel Limited, Jamshedpur 831001
3 S. CHAKRABORTY R& D Tata Steel Limited, Jamshedpur 831001
PCT International Classification Number B04C5/107;B03B5/28
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 NA