Title of Invention	SAND CUSHIONED RAFT FOUNDATION FOR RETROFIT ELECTROSTATIC PRECIPITATORS IN THERMAL POWER PLANTS TO AVOID DISMANTLING OF EXISTING FOUNDATIONS
Abstract	A sand cushioned raft foundation (1) for retrofit electrostatic precipitators comprising - a sand cushion (2) provided over existing foundation footing (4), - a plurality of pedestals (6) which support the columns of the retrofit electrostatic precipitator and - a cantilever (5) from an outer pedestal (6), characterized in that the said raft foundation makes installation of retrofit electrostatic precipitators possible without dismantling of existing foundations.

Title of Invention

SAND CUSHIONED RAFT FOUNDATION FOR RETROFIT ELECTROSTATIC PRECIPITATORS IN THERMAL POWER PLANTS TO AVOID DISMANTLING OF EXISTING FOUNDATIONS

Abstract

A sand cushioned raft foundation (1) for retrofit electrostatic precipitators comprising - a sand cushion (2) provided over existing foundation footing (4), - a plurality of pedestals (6) which support the columns of the retrofit electrostatic precipitator and - a cantilever (5) from an outer pedestal (6), characterized in that the said raft foundation makes installation of retrofit electrostatic precipitators possible without dismantling of existing foundations.

Full Text	FIELD OF THE INVENTION This invention relates generally to foundations of electrostatic precipitators in thermal power plants, more particularly the invention relates to a sand cushioned raft foundation for retrofit electrostatic precipitators in thermal power plants in poor soil conditions which avoids dismantling of existing foundations. BACKGROUND AND PRIOR ART Electrostatic precipitator is an equipment in a thermal power plant which extracts the ash which comes along with the flue gas which is the product of burning pulverized coal in a boiler in the thermal power plant. The electrostatic precipitator uses the electrical phenomenon called "corona" discharge which under high voltage turns the flue gas into a ionized state where the negatively charged ash particles are attracted towards the positive electrodes called collecting electrodes which is rapped at intervals and collected in the ash hoppers at the bottom of the electrostatic precipitators. The weight of the collected ash and the weight of the collecting electrodes constitute the major vertical loads on the foundations of the supporting structure of the electrostatic precipitators apart from the wind and seismic loads. The electrostatic precipitators are designed for a particular value of permissible emission levels i.e. (the amount of dust particles present in the flue gas that is let into the atmosphere through the chimney). These emission levels are normally fixed by the pollution control boards of the Central/State Governments. The permissible emission levels had been revised at intervals and in 1980's these values were around 150mg/NM3 to around 50mg/NM3 now. The revision in the permitted emission levels require the modification to the already installed electrostatic precipitators designed for a higher emission levels to bring down the emission level to the current norms. The revision increases the vertical load on the foundation of the electrostatic precipitator as both the amount of collected ash and size of the collecting electrodes increase considerably. Most of the times the electrostatic precipitators are dismantled and newly designed bigger electrostatic precipitators are installed to satisfy the current emission norms. This process of dismantling the existing electrostatic precipitator and installing a new bigger electrostatic precipitator in the same location i.e. between the boiler and the induced draft fan is called retrofitting. The retrofitting of electrostatic precipitator involves the dismantling of electrostatic precipitator's and its foundations, most of the times, and the new foundations of the new electrostatic precipitator is cast in the old location designed for new loads. Dismantling of old foundation is always a laborious and time consuming work which is normally done using "jack hammers". The time taken for the dismantling of the reinforced cement concrete foundation having steel reinforcement in the concrete is more than that of plain cement concrete foundations and all the foundations of electrostatic precipitators are of reinforced cement concrete only. To avoid the dismantling of existing old foundations in a retrofitting of electrostatic precipitator the foundations are designed in such a way that the interferences of the existing foundations are avoided using different shapes of foundations other than the normal, square or rectangular foundation. The size and shape of the foundations designed is tailor made for particular location at particular site and cannot be standardized. Sometimes the existing foundations of the old electrostatic precipitators are modified to take the additional load due to the bigger new electrostatic precipitator. This is possible in some cases depending upon the locations of the old electrostatic precipitator columns with respect to the new electrostatic precipitator columns. In the prior art, at times grade beams on top of the existing foundations are used to support the new electrostatic precipitator columns if the new electrostatic precipitator column loads are not beyond the load carrying capacity of the old foundations. Additional columns can also be introduced if necessary to augment the load carrying capacity of the existing columns along with the grade beams if the loads from the new electrostatic precipitators are higher than the load carry capacities of the existing foundations. At times a single isolated foundation can be strengthened to take additional loads by increasing size of the base of the footing and the pedestals which support the electrostatic precipitator columns. These modifications always involve chipping of concrete using jack hammers, welding of reinforcement, providing additional concrete and application of bonding agent which is also a time consuming job which takes about the same time which is required for the dismantling of the old foundation. The modifications of existing foundations or strengthening of the existing foundation to carry additional loads can be done only in cases where the existing concrete is of the grade which is permitted by the new Indian Standards (IS-456-2000). For example the earlier codes permitted M-15 grade for Reinforced cement concrete foundation in 1980's and M-25 is the minimum grade of concrete that can be used in foundations at present as per IS-456-2000. Since the retrofitting of electrostatic precipitators are normally done after about 20 years, the grade of concrete in the existing foundation will be normally lower than the grade permitted in the present Indian Standards (IS- 456-2000). This warrants the retrofit electrostatic precipitators are to be provided with new foundations. The new foundations of the electrostatic precipitators are normally designed as simple isolated foundations where the soil conditions are very good. Pile foundations are provided in places where the soil conditions are very bad. Pile foundations are special foundations cast in to the holes drilled into the earth for about 10 to 25m, with special machinery for drilling and casting of reinforced cement concrete piles. The present invention provides a novel alternative which is the raft or mat foundation interconnecting all the columns of a new electrostatic precipitator unlike the other two type of foundation namely isolated foundations and pile foundations where the foundations are provided for a single column. The raft foundations are normally used in poor soil conditions. They are comparatively cheaper than the pile foundations in a poor soil condition but can be cast using conventional concreting equipment unlike pile foundation which needs special machinery for drilling and casting. The bearing capacity of the soil of a raft foundation in almost double than that of the isolated foundations for the same soil type and settlements are also almost 50% less than that of the isolated foundations. Because space availability in a retrofit electrostatic precipitator site is always critical since the old electrostatic precipitator is always replaced with a bigger electrostatic precipitator and the original layout of machines are not designed for future expansion, the raft foundation is ideal because raft foundation occupies the minimum foot print. The present invention seeks to overcome the drawbacks of the prior art. OBJECTS OF THE INVENTION: It is therefore an object of the invention to provide a sand cushioned raft foundation for the retrofit Electrostatic Precipitators in thermal power plants which avoids the dismantling of the existing foundation footings. Another object of the invention to provide sand cushioned Raft Foundation for Retrofit Electrostatic Precipitators adapted to thermal Power Plant which is cheaper and requires less time to execute than dismantling the existing foundations and making a new foundation. Another object of the invention to provide sand cushioned raft foundation for retrofit electrostatic precipitator which has an increased bearing capacity than that of a normal isolated foundation. Yet another object of the invention is to provide sand cushioned raft foundation for retrofit electrostatic precipitator in thermal power plants which have less settlement for the same soil condition and loads compared to normal isolated foundations. A further object of the invention is to provide a sand cushioned raft foundation for retrofit electrostatic precipitator in thermal power plants which does not need any special equipment to cast the foundations like in the case of pile foundations. A still further object of the invention is to provide sand cushioned raft foundation for retrofit electrostatic precipitator in thermal power plants, to reduce the footprint required for the foundation. A still further object of the invention is to provide sand cushioned raft foundation for retrofit electrostatic precipitator in thermal power plants, in which fly ash, a recycled material can be used instead of sand for the back fill. Fly ash is an environmentally 'green' material. A still further object of the invention is to provide a one meter cantilever from the edge of the pedestals to reduce the pressure on the sand cushion. A still further object of the invention is to provide a bigger than normal size of pedestals to reduce the punching shear capacity of the raft foundations. SUMMARY OF INVENTION: According to the invention, the sand cushioned raft foundation for electrostatic precipitator is cast about one meter above the existing foundation footing top level. Sand is used as a back filling material between the existing foundation and the new raft foundation which acts as a cushion. The pedestals of the existing foundation alone are removed from the footing by chipping along the edges to expose the reinforcements and after cutting the exposed reinforcements along the periphery of the pedestal bottom, the pedestal is pushed down using a hydraulic crane and removed from site. Excavation is done initially up to the bottom of existing foundations and entire originally backfilled material is removed before sand filling. Good coarse river sand is used for backfilling . The bearing capacity of the sand used for backfilling is always higher than the bearing pressure of the raft foundation, which is always low because of the large area of the raft foundation. The soil cushion avoids the increased local stresses which the new raft foundation will be subjected to if the new foundation is put on top of the old foundation without soil cushion. Murram /fly ash/quarry dust/plain cement concrete can also be used effectively as the backfilling material instead of sand according to the availability of the material locally at cheaper cost. The raft foundation with soil cushion avoids dismantling of footings of the old existing foundations which involves both time and money. BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWING: Fig.l. shows the sectional elevation of the sand cushioned raft foundation for retrofit electrostatic precipitator in thermal power plants, according to the invention. DETAILED DESCRIPTION OF THE INVENTION: A raft foundation (1) for a retrofit electrostatic precipitator in thermal power plants exerts very low pressure on the soil because of its vast area as the foundation interconnects all the columns of an electrostatic precipitator. According to the invention the material for the sand cushion (2) used for backfilling can also murram/ fly ash/ quarry dust/ plain cement concrete, according to the availability of the material at lower cost. The thickness of the sand cushion (2) is at least lm to avoid local stresses on the raft due to the existing foundation below. The raft foundation (1) foot print is the lowest among other types of foundation used in retrofit electrostatic precipitator foundations, namely isolated and pile foundation. Because of the large area of the raft, the settlement of foundation is lower than that of the normal isolated foundations. The old pedestals (3) of the existing foundation alone are removed by chipping the edges along the periphery at the bottom of the pedestal (3) and pushing the pedestals (3) down with hydraulic crane. The footings (4) of the old foundations are not dismantled and the sand cushion is provided above the footings. The sand cushioned raft foundation (1) considerably reduces the unequal settlements of the foundation compared to normal isolated foundations. The sand cushion (2) distributes the pressure uniformly to the soil below and to the footing of the existing foundation. The raft foundation can be designed as a flexible foundation using available software because of the soil cushion. The raft foundation (1) according to the invention has very low bearing pressure in the range of 6 to 10 T/m2. This raft foundation (1) is provided with a cantilever(5) which is lm long, from the outer pedestals(6) to reduce the corner and edge stresses. The cantilever (5) also reduces the bearing pressure by 15-20%. The pedestals (6) which rest over the raft foundation (1) support the columns of the retrofit electrostatic precipitation. These pedestals (6) are provided in size of 1.2m x 1.2m against lm x lm in prior art, to reduce therein punching shear stress. The sand cushioned raft foundation (1) can be used for all retrofit electrostatic precipitators irrespective of the size and in any soil condition. We Claim: 1. A sand cushioned raft foundation (1) for retrofit electrostatic precipitators comprising - a sand cushion (2) provided over existing foundation footing (4), - a plurality of pedestals (6) which support the columns of the retrofit electrostatic precipitator and - a cantilever (5) from an outer pedestal (6), characterized in that the said raft foundation makes installation of retrofit electrostatic precipitators possible without dismantling of existing foundations. 2. A raft foundation (1) as claimed in claim 1, wherein the material for the sand cushion (2) can also be murram/ fly ash/ quarry dust/ plain cement concrete, according to the availability of the material at lower cost. 3. A raft foundation (1) as claimed in claim 1, wherein the foundation (1) is made of reinforced cement concrete. 4. A raft foundation (1) as claimed in claim 1, wherein the thickness of the sand cushion (2) is at least 1 m. 5. A raft foundation (1) as claimed in claim 1, wherein the foundation interconnects all the columns of the electrostatic precipitator, and has the lowest footprint compared to all other foundations of prior art. 6. A raft foundation (1) as claimed in claim 1, which has low bearing pressure in the range of 6 to 10 T/m2, making it suitable for poor soil conditions. 7. A raft foundation (1) as claimed in claim l, wherein the cantilever (5) is lm long from outer pedestal (6) and reduces the bearing pressure of the raft foundation (1) by 15-20%. 8. A raft foundation (1) as claimed in claim 1, wherein the pedestals (6) are sized 1.2m x 1.2m to reduce the punching shear stress . 9. A raft foundation (1) as claimed in claim 1, wherein the foundation can be deployed for all retrofit electrostatic precipitators irrespective of their size and in any soil condition. A sand cushioned raft foundation (1) for retrofit electrostatic precipitators comprising - a sand cushion (2) provided over existing foundation footing (4), - a plurality of pedestals (6) which support the columns of the retrofit electrostatic precipitator and - a cantilever (5) from an outer pedestal (6), characterized in that the said raft foundation makes installation of retrofit electrostatic precipitators possible without dismantling of existing foundations.

Full Text

FIELD OF THE INVENTION
This invention relates generally to foundations of electrostatic precipitators in
thermal power plants, more particularly the invention relates to a sand
cushioned raft foundation for retrofit electrostatic precipitators in thermal
power plants in poor soil conditions which avoids dismantling of existing
foundations.
BACKGROUND AND PRIOR ART
Electrostatic precipitator is an equipment in a thermal power plant which
extracts the ash which comes along with the flue gas which is the product of
burning pulverized coal in a boiler in the thermal power plant.
The electrostatic precipitator uses the electrical phenomenon called "corona"
discharge which under high voltage turns the flue gas into a ionized state
where the negatively charged ash particles are attracted towards the positive
electrodes called collecting electrodes which is rapped at intervals and
collected in the ash hoppers at the bottom of the electrostatic precipitators.
The weight of the collected ash and the weight of the collecting electrodes
constitute the major vertical loads on the foundations of the supporting

structure of the electrostatic precipitators apart from the wind and seismic
loads.
The electrostatic precipitators are designed for a particular value of
permissible emission levels i.e. (the amount of dust particles present in the
flue gas that is let into the atmosphere through the chimney). These emission
levels are normally fixed by the pollution control boards of the Central/State
Governments.
The permissible emission levels had been revised at intervals and in 1980's
these values were around 150mg/NM3 to around 50mg/NM3 now.
The revision in the permitted emission levels require the modification to the
already installed electrostatic precipitators designed for a higher emission
levels to bring down the emission level to the current norms. The revision
increases the vertical load on the foundation of the electrostatic precipitator
as both the amount of collected ash and size of the collecting electrodes
increase considerably.
Most of the times the electrostatic precipitators are dismantled and newly
designed bigger electrostatic precipitators are installed to satisfy the current
emission norms.
This process of dismantling the existing electrostatic precipitator and
installing a new bigger electrostatic precipitator in the same location i.e.
between the boiler and the induced draft fan is called retrofitting.

The retrofitting of electrostatic precipitator involves the dismantling of
electrostatic precipitator's and its foundations, most of the times, and the
new foundations of the new electrostatic precipitator is cast in the old
location designed for new loads.
Dismantling of old foundation is always a laborious and time consuming work
which is normally done using "jack hammers". The time taken for the
dismantling of the reinforced cement concrete foundation having steel
reinforcement in the concrete is more than that of plain cement concrete
foundations and all the foundations of electrostatic precipitators are of
reinforced cement concrete only.
To avoid the dismantling of existing old foundations in a retrofitting of
electrostatic precipitator the foundations are designed in such a way that the
interferences of the existing foundations are avoided using different shapes of
foundations other than the normal, square or rectangular foundation. The
size and shape of the foundations designed is tailor made for particular
location at particular site and cannot be standardized.
Sometimes the existing foundations of the old electrostatic precipitators are
modified to take the additional load due to the bigger new electrostatic
precipitator. This is possible in some cases depending upon the locations of
the old electrostatic precipitator columns with respect to the new electrostatic
precipitator columns.
In the prior art, at times grade beams on top of the existing foundations are
used to support the new electrostatic precipitator columns if the new

electrostatic precipitator column loads are not beyond the load carrying
capacity of the old foundations.
Additional columns can also be introduced if necessary to augment the load
carrying capacity of the existing columns along with the grade beams if the
loads from the new electrostatic precipitators are higher than the load carry
capacities of the existing foundations.
At times a single isolated foundation can be strengthened to take additional
loads by increasing size of the base of the footing and the pedestals which
support the electrostatic precipitator columns.
These modifications always involve chipping of concrete using jack hammers,
welding of reinforcement, providing additional concrete and application of
bonding agent which is also a time consuming job which takes about the
same time which is required for the dismantling of the old foundation.
The modifications of existing foundations or strengthening of the existing
foundation to carry additional loads can be done only in cases where the
existing concrete is of the grade which is permitted by the new Indian
Standards (IS-456-2000). For example the earlier codes permitted M-15
grade for Reinforced cement concrete foundation in 1980's and M-25 is the
minimum grade of concrete that can be used in foundations at present as per
IS-456-2000.
Since the retrofitting of electrostatic precipitators are normally done after
about 20 years, the grade of concrete in the existing foundation will be
normally lower than the grade permitted in the present Indian Standards (IS-

456-2000). This warrants the retrofit electrostatic precipitators are to be
provided with new foundations.
The new foundations of the electrostatic precipitators are normally designed
as simple isolated foundations where the soil conditions are very good. Pile
foundations are provided in places where the soil conditions are very bad.
Pile foundations are special foundations cast in to the holes drilled into the
earth for about 10 to 25m, with special machinery for drilling and casting of
reinforced cement concrete piles.
The present invention provides a novel alternative which is the raft or mat
foundation interconnecting all the columns of a new electrostatic precipitator
unlike the other two type of foundation namely isolated foundations and pile
foundations where the foundations are provided for a single column.
The raft foundations are normally used in poor soil conditions. They are
comparatively cheaper than the pile foundations in a poor soil condition but
can be cast using conventional concreting equipment unlike pile foundation
which needs special machinery for drilling and casting.
The bearing capacity of the soil of a raft foundation in almost double than
that of the isolated foundations for the same soil type and settlements are
also almost 50% less than that of the isolated foundations.
Because space availability in a retrofit electrostatic precipitator site is always
critical since the old electrostatic precipitator is always replaced with a bigger
electrostatic precipitator and the original layout of machines are not designed

for future expansion, the raft foundation is ideal because raft foundation
occupies the minimum foot print.
The present invention seeks to overcome the drawbacks of the prior art.
OBJECTS OF THE INVENTION:
It is therefore an object of the invention to provide a sand cushioned raft
foundation for the retrofit Electrostatic Precipitators in thermal power plants
which avoids the dismantling of the existing foundation footings.
Another object of the invention to provide sand cushioned Raft Foundation
for Retrofit Electrostatic Precipitators adapted to thermal Power Plant which is
cheaper and requires less time to execute than dismantling the existing
foundations and making a new foundation.
Another object of the invention to provide sand cushioned raft foundation for
retrofit electrostatic precipitator which has an increased bearing capacity than
that of a normal isolated foundation.
Yet another object of the invention is to provide sand cushioned raft
foundation for retrofit electrostatic precipitator in thermal power plants which
have less settlement for the same soil condition and loads compared to
normal isolated foundations.
A further object of the invention is to provide a sand cushioned raft
foundation for retrofit electrostatic precipitator in thermal power plants which
does not need any special equipment to cast the foundations like in the case
of pile foundations.

A still further object of the invention is to provide sand cushioned raft
foundation for retrofit electrostatic precipitator in thermal power plants, to
reduce the footprint required for the foundation.
A still further object of the invention is to provide sand cushioned raft
foundation for retrofit electrostatic precipitator in thermal power plants, in
which fly ash, a recycled material can be used instead of sand for the back
fill. Fly ash is an environmentally 'green' material.
A still further object of the invention is to provide a one meter cantilever from
the edge of the pedestals to reduce the pressure on the sand cushion.
A still further object of the invention is to provide a bigger than normal size of
pedestals to reduce the punching shear capacity of the raft foundations.
SUMMARY OF INVENTION:
According to the invention, the sand cushioned raft foundation for
electrostatic precipitator is cast about one meter above the existing
foundation footing top level.
Sand is used as a back filling material between the existing foundation and
the new raft foundation which acts as a cushion.
The pedestals of the existing foundation alone are removed from the footing
by chipping along the edges to expose the reinforcements and after cutting
the exposed reinforcements along the periphery of the pedestal bottom, the
pedestal is pushed down using a hydraulic crane and removed from site.

Excavation is done initially up to the bottom of existing foundations and
entire originally backfilled material is removed before sand filling.
Good coarse river sand is used for backfilling .
The bearing capacity of the sand used for backfilling is always higher than the
bearing pressure of the raft foundation, which is always low because of the
large area of the raft foundation.
The soil cushion avoids the increased local stresses which the new raft
foundation will be subjected to if the new foundation is put on top of the old
foundation without soil cushion.
Murram /fly ash/quarry dust/plain cement concrete can also be used
effectively as the backfilling material instead of sand according to the
availability of the material locally at cheaper cost.
The raft foundation with soil cushion avoids dismantling of footings of the old
existing foundations which involves both time and money.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWING:
Fig.l. shows the sectional elevation of the sand cushioned raft foundation for
retrofit electrostatic precipitator in thermal power plants, according to the
invention.

DETAILED DESCRIPTION OF THE INVENTION:
A raft foundation (1) for a retrofit electrostatic precipitator in thermal power
plants exerts very low pressure on the soil because of its vast area as the
foundation interconnects all the columns of an electrostatic precipitator.
According to the invention the material for the sand cushion (2) used for
backfilling can also murram/ fly ash/ quarry dust/ plain cement concrete,
according to the availability of the material at lower cost. The thickness of the
sand cushion (2) is at least lm to avoid local stresses on the raft due to the
existing foundation below.
The raft foundation (1) foot print is the lowest among other types of
foundation used in retrofit electrostatic precipitator foundations, namely
isolated and pile foundation.
Because of the large area of the raft, the settlement of foundation is lower
than that of the normal isolated foundations.
The old pedestals (3) of the existing foundation alone are removed by
chipping the edges along the periphery at the bottom of the pedestal (3) and
pushing the pedestals (3) down with hydraulic crane.
The footings (4) of the old foundations are not dismantled and the sand
cushion is provided above the footings.
The sand cushioned raft foundation (1) considerably reduces the unequal
settlements of the foundation compared to normal isolated foundations.

The sand cushion (2) distributes the pressure uniformly to the soil below and
to the footing of the existing foundation.
The raft foundation can be designed as a flexible foundation using available
software because of the soil cushion.
The raft foundation (1) according to the invention has very low bearing
pressure in the range of 6 to 10 T/m2. This raft foundation (1) is provided
with a cantilever(5) which is lm long, from the outer pedestals(6) to reduce
the corner and edge stresses. The cantilever (5) also reduces the bearing
pressure by 15-20%.
The pedestals (6) which rest over the raft foundation (1) support the columns
of the retrofit electrostatic precipitation. These pedestals (6) are provided in
size of 1.2m x 1.2m against lm x lm in prior art, to reduce therein punching
shear stress.
The sand cushioned raft foundation (1) can be used for all retrofit
electrostatic precipitators irrespective of the size and in any soil condition.

We Claim:
1. A sand cushioned raft foundation (1) for retrofit electrostatic precipitators
comprising
- a sand cushion (2) provided over existing foundation footing (4),
- a plurality of pedestals (6) which support the columns of the retrofit
electrostatic precipitator and
- a cantilever (5) from an outer pedestal (6), characterized in that the said
raft foundation makes installation of retrofit electrostatic precipitators possible
without dismantling of existing foundations.

2. A raft foundation (1) as claimed in claim 1, wherein the material for the
sand cushion (2) can also be murram/ fly ash/ quarry dust/ plain cement
concrete, according to the availability of the material at lower cost.
3. A raft foundation (1) as claimed in claim 1, wherein the foundation (1) is
made of reinforced cement concrete.
4. A raft foundation (1) as claimed in claim 1, wherein the thickness of the
sand cushion (2) is at least 1 m.
5. A raft foundation (1) as claimed in claim 1, wherein the foundation
interconnects all the columns of the electrostatic precipitator, and has the
lowest footprint compared to all other foundations of prior art.
6. A raft foundation (1) as claimed in claim 1, which has low bearing pressure
in the range of 6 to 10 T/m2, making it suitable for poor soil conditions.

7. A raft foundation (1) as claimed in claim l, wherein the cantilever (5) is lm
long from outer pedestal (6) and reduces the bearing pressure of the raft
foundation (1) by 15-20%.
8. A raft foundation (1) as claimed in claim 1, wherein the pedestals (6) are
sized 1.2m x 1.2m to reduce the punching shear stress .
9. A raft foundation (1) as claimed in claim 1, wherein the foundation can be
deployed for all retrofit electrostatic precipitators irrespective of their size and
in any soil condition.

A sand cushioned raft foundation (1) for retrofit electrostatic precipitators
comprising
- a sand cushion (2) provided over existing foundation footing (4),
- a plurality of pedestals (6) which support the columns of the retrofit electrostatic precipitator and
- a cantilever (5) from an outer pedestal (6), characterized in that the said raft foundation makes installation of retrofit electrostatic precipitators possible without dismantling of existing foundations.

Documents:

1440-KOL-2013-(16-05-2014)-CORRESPONDENCE.pdf

1450-KOL-2008-(03-03-2014)-FORM-27.pdf

1450-KOL-2008-(03-04-2013)-CORRESPONDENCE.pdf

1450-KOL-2008-(13-12-2012)-CORRESPONDENCE.pdf

1450-KOL-2008-(16-05-2014)-ABSTRACT.pdf

1450-KOL-2008-(16-05-2014)-CLAIMS.pdf

1450-KOL-2008-(16-05-2014)-CORRESPONDENCE.pdf

1450-KOL-2008-(16-05-2014)-DESCRIPTION (COMPLETE).pdf

1450-KOL-2008-(16-05-2014)-DRAWINGS.pdf

1450-KOL-2008-(16-05-2014)-FORM-1.pdf

1450-KOL-2008-(16-05-2014)-FORM-2.pdf

1450-KOL-2008-(17-04-2013)-CORRESPONDENCE.pdf

1450-KOL-2008-(17-06-2013)-CORRESPONDENCE.pdf

1450-KOL-2008-(21-05-2013)-CORRESPONDENCE.pdf

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Patent Number

265596

Indian Patent Application Number

1450/KOL/2008

PG Journal Number

10/2015

Publication Date

06-Mar-2015

Grant Date

27-Feb-2015

Date of Filing

26-Aug-2008

Name of Patentee

BHARAT HEAVY ELECTRICALS LIMITED

Applicant Address

REGIONAL OPERATIONS DIVISION (ROD), PLOT NO : 9/1, DJBLOCK, 3RD FLOOR, KARUNAMOYEE, SALT LAKE CITY, KOLKATA - 700091, HAVING ITS REGISTERED OFFICE AT BHEL HOUSE, SIRI FORT, NEW DELHI – 110049

Inventors:

#	Inventor's Name	Inventor's Address
1	CHINNASAMY CHELLADURAI	BHARAT HEAVY ELECTRICALS LIMITED RANIPET - 632 406
2	SETHURAMAN RAMESH	BHARAT HEAVY ELECTRICALS LIMITED RANIPET - 632 406
3	PITCHANDI SANKARAPANDIAN	BHARAT HEAVY ELECTRICALS LIMITED RANIPET - 632 406
4	SELVADURAI ARIVALAGAN	BHARAT HEAVY ELECTRICALS LIMITED RANIPET - 632 406
5	VASUDEVAN DHINAKHAR	BHARAT HEAVY ELECTRICALS LIMITED RANIPET - 632 406

PCT International Classification Number

B03C3/47; B03C3/86; B03C3/34;

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA