Title of Invention	A WASTE HEAT RECOVERY BOILER/ECONOMISER FOR DUST LADEN FLUE GASES
Abstract	A waste heat recovery boiler and economizer for dust laden flue gases consists of water tube type boiler and economizer made with slender tubes arranged one above the other; the said tubes in one row having the common header at the top and bottom forming one cassette of the row; plurality of such said cassettes are kept adjacent to each other forming square matrix of the tubes; all such tubes are supported at the top to hang freely; intermediate horizontal supports are provided between the tubes at regular interval to prevent bending of the said tubes; top face of the said intermediate horizontal supports is given inclination of about 60 slant with respect to the horizontal so that dust falling on the said supports falls freely and does not accumulate or deposit on the same, ensuring higher heat transfer effectiveness.

Title of Invention

A WASTE HEAT RECOVERY BOILER/ECONOMISER FOR DUST LADEN FLUE GASES

Abstract

A waste heat recovery boiler and economizer for dust laden flue gases consists of water tube type boiler and economizer made with slender tubes arranged one above the other; the said tubes in one row having the common header at the top and bottom forming one cassette of the row; plurality of such said cassettes are kept adjacent to each other forming square matrix of the tubes; all such tubes are supported at the top to hang freely; intermediate horizontal supports are provided between the tubes at regular interval to prevent bending of the said tubes; top face of the said intermediate horizontal supports is given inclination of about 60 slant with respect to the horizontal so that dust falling on the said supports falls freely and does not accumulate or deposit on the same, ensuring higher heat transfer effectiveness.

Full Text	FORM-2 THE PATENTS ACT. 1970 (39 of 1970) COMPLETE SPECIFICATION (Section 10) "A WASTE HEAT RECOVERY BOILER/ECONOMISERFOR DUST LADEN FLUE GASES" ASHOK D ATTATRAYA ATRE, 'Pushpa Heights', 1st floor, Bibwewadi Corner, PUNE-411027. Maharashtra State, India An Indian Citizen The following specification particularly describes the nature of the invention and the manner in which it is to be performed:- Present invention relates to a Waste Heat Recovery Boiler and Economizer for dust laden flue gases. While doing Waste Heat Recovery in various plants like Cement Plant, Steel Plant, Foundries etc, the flue gases come out of the above plants are invariably heavily dust laden. This dust removal as well as prevention of settling of the dust on the heat transfer surface becomes an important aspect in designing these waste heat recovery boilers. Till date no such waste heat recovery boiler/ economizer for dust laden flue gases are in existence which would serve the purpose of removing the dust from the flue gases and reutilise the energy present in the flue gases, as well as prevent the settling of the dust on the heat transfer surface. It is the object of the present invention to develop a Waste Heat Recovery Boiler/ Economizer for dust laden flue gases. It is also the object of the present invention to reutilise the energy present in the flue gases. Accordingly the present provides for A waste heat recovery boiler and economizer for dust laden flue gases comprising: water tube type boiler and economizer made with slender tubes arranged one above the other; the said tubes in one row having a common header at the top and bottom forming one cassette of the row; plurality of such said cassettes are kept adjacent to each other forming square matrix of the tubes; all such tubes are supported only at the top to hang freely; there are provided. intermediate horizontal supports between the gaps of the said tubes at regular intervals for preventing bending, top side of the said supports is given inclination of about 60° slant with respect to horizontal so that the dust falling on the said supports falls freely and doesn't accumulate or deposit on the same ensuring higher heat transfer effectiveness. The invention is described with reference to the accompanying drawings wherein: Figure 1 shows the layout of waste heat recovery boiler and economizer for dust laden flue gases according to this invention. Figure 2 shows the typical construction of water tube type boiler and economizer for dust laden flue gases according to this invention. Now referring to the figures of the accompanying drawing, waste heat recovery boiler (1) and economizer (2) for dust laden flue gases comprises number of slender tubes (3) arranged one above the other vertically. Water (8) is inside the said tubes (3) and flue gas (9) outside the said tube (3). The each of the said Tubes (3) in one row have a common header (5) at the top and bottom forming one cassette of that row. Many such cassettes are kept adjacent to each other forming square matrix of the tubes (3). All these said tubes (3) are supported only at the top so that they are freely hanging under self-weight of the boiler / economizer. This eliminates possibilities of the said tube (3) buckling due to thermal expansion. Intermediate horizontal supports (6) are provided between the gaps at regular intervals of about 1.5 meter. These supports prevent the bending of the said tubes (3). Also vibrators / hammers (7) can be given on these supports so that the removal of dust from the tube surface can be done easily. The top face of these said supports (6) is given inclination of about 60° with respect to horizontal. Hence powder falls freely from those and doesn't accumulate on the top face of supports. The hot gases with dust and the like enter the system from the top and move downwards.Velocity of the gases is kept lower so that dust powder separates by gravity and pressure drop across the system remains minimum & keeps exhaust gas handling fan power to minimum. 1. The "Co-current down flow arrangement" for air and dust greatly enhances the movement of separated dust to the lower portion without accumulation or deposition in the system, minimizing / eliminating fouling or choking. The gravitational flow of the powder also eliminates additional power requirement for its conveying. The steam (10) generated is stored in a steam drum (4) having various safety mountings and controls. The system is fully automatic. 2. Automation 4s either based on preprogrammed on & off cycle timing of vibrators / Hammers (7) or it works on gas pressure drop across the said boiler (1). The automatic system working on Flue Gas Pressure is as follows: A separate differential gas pressure switch (not shown in the figure) is provided across the boiler (1) & economizer (2). If the pressure drop increases beyond desired set point (set level) the vibrators / hammers (7) will work "continuously" or "continuously cyclically" till pressure drop comes back within desired limit. Powder dislodged from the said tube (3) surfaces due to hammering / vibrations fall freely downwards without obstruction through uniform flue gas (9) passage. Details of components in figure 1 and 2 :- Details of components in figure 1 and 2 :- Boiler 1, Economizer 2, Slender tubes 3, Steam drum 4, Header 5, Intermediate horizontal supports 6, Vibrators / hammers 7, Water 8, Fiue gas 9, Steam 10 The salient features are as follows: Boilers and economizers are water tube type with tubes hanging vertically. Water is inside the tubes and flue gas outside the tube. Tubes have intermediate supports at about 1.5-meter pitch, which keep the tubes straight. The top face of intermediate supports are given 60° slant angle from horizontal, so that dust cake dislodged from tube surface does not accumulate on these supports but slides down easily on the slant. The downwards flow of the fiue gases and gravity fall of dust cake greatly and easily "co-operate" each other to reach bottom with following advantages:- A) The flue gas velocities can be much lower than pneumatic conveying velocities. This benefits in - Lower frictional pressure loss in flue gas flow saving energy in fan power required. Gravitational energy used for dust. Hence fiue gas doesn't have to be imparted additional energy, otherwise pneumatic conveying, saving pneumatic conveying energy. This greatly increases net electrical energy exported for external use. B) Vertical downward "parallel to heat transfer area" flue gas flow with free flowing gravity force driven dust cake eliminates any possibility of re-deposition of dust on the tubes. Due to this the boiler heat recovery is very effective and tube fouling (which reduces effectiveness of heat transfer area) is lowest. If the fouling were to be high, then the heating surface required would have to be much higher. Increase in boiler heating surface, increases boiler steel requirement, increases dry and operating wet of boiler. The increased boiler weight increases structural support steel quantities. All these greatly increase initial cost (capital cost) of the equipment. Therefore, the clean surfaces means lower first cost, also if boiler has higher heating surface it has higher flue gas pressure drop (flue gas frictional resistance). So fan consumes more power reducing net power exported from heat recovery co-generation system. Therefore excessive fouling of 'Heat Transfer Surface' will reduce the commercial viability of the project. Mechanical vibrators or hammers (8) are provided to dislodge the powder deposited on the surface. 3. All the tube headers are supported at the top only so that - a) Tubes remain straight avoiding buckling. b) Tubes are free to expand thermally which leaves the system without any strain. c) Tubes remain in tension by force equal to gravity weight of the boiler, giving better life. Since metal has higher tensile strength than compressive strength. Advantages of the present invention : 1. Low pressure drop on the flue-gas, conserving fan power. 2. Rue gas and dislodged dust both move in the downward direction resulting in the seif-cieaning process. 3. Automatic vibrators / mechanicai hammers disiodge the settied powder easily. 4. Free hanging tube design under seif-weight prevents bending / buckiing of the tubes. 5. Dust deposition and fouiing being avoided, heat transfer effectiveness is ensured. I CLAIM :- 1. A waste heat recovery boiler and economizer for dust laden flue gases comprising water tube type boiler and economizer made with slender tubes arranged one above the other; the said tubes in one row having the common header at the top and bottom forming one cassette of the row; plurality of such said cassettes are kept adjacent to each other forming square matrix of the tubes; all such tubes are supported at the top to hang freely; intermediate horizontal supports are provided between the tubes at regular interval to prevent bending of the said tubes; top face of the said intermediate horizontal supports is given inclination of about 60° slant with respect to the horizontal so that dust falling on the said supports falls freely and doesn't accumulate or deposit on the same ensuring higher heat transfer effective. 2. A waste heat recovery boiler and economizer for dust laden flue gases as claimed in claim 1 wherein the said intermediate horizontal supports are provided with automatic vibrators/ mechanical hammers to dislodge the settled powder. 3. A waste heat recovery boiler and economizer for dust laden flue gases as claimed in claim 1 and 2 along with the steam drum to collect the generated steam. 4. A waste heat boiler and economizer for dust laden flue gases as claimed in claim 1 to 3 and as herein described with reference to the figures of the accompanying drawings. Dated this 6th Day of Jutte,2001

Full Text

FORM-2
THE PATENTS ACT. 1970 (39 of 1970)
COMPLETE SPECIFICATION
(Section 10)
"A WASTE HEAT RECOVERY BOILER/ECONOMISERFOR DUST LADEN
FLUE GASES"
ASHOK D ATTATRAYA ATRE, 'Pushpa Heights', 1st floor, Bibwewadi Corner,
PUNE-411027. Maharashtra State, India An Indian Citizen
The following specification particularly describes the nature of the invention and the manner in which it is to be performed:-

Present invention relates to a Waste Heat Recovery Boiler and Economizer for dust laden flue gases.
While doing Waste Heat Recovery in various plants like Cement Plant, Steel Plant, Foundries etc, the flue gases come out of the above plants are invariably heavily dust laden. This dust removal as well as prevention of settling of the dust on the heat transfer surface becomes an important aspect in designing these waste heat recovery boilers.
Till date no such waste heat recovery boiler/ economizer for dust laden flue gases are in existence which would serve the purpose of removing the dust from the flue gases and reutilise the energy present in the flue gases, as well as prevent the settling of the dust on the heat transfer surface.
It is the object of the present invention to develop a Waste Heat Recovery Boiler/ Economizer for dust laden flue gases.
It is also the object of the present invention to reutilise the energy present in the flue gases.
Accordingly the present provides for A waste heat recovery boiler and economizer for dust laden flue gases comprising:
water tube type boiler and economizer made with slender tubes arranged one above the other; the said tubes in one row having a common header at the top and bottom forming one cassette of the row; plurality of such said cassettes are kept adjacent to each other forming square matrix of the tubes; all such tubes are supported only at the top to hang freely; there are provided. intermediate horizontal supports between the gaps of the said tubes at regular intervals for preventing bending, top side of the

said supports is given inclination of about 60° slant with respect to horizontal so that the dust falling on the said supports falls freely and doesn't accumulate or deposit on the same ensuring higher heat transfer effectiveness.
The invention is described with reference to the accompanying drawings wherein:
Figure 1 shows the layout of waste heat recovery boiler and economizer for dust laden flue gases according to this invention.
Figure 2 shows the typical construction of water tube type boiler and economizer for dust laden flue gases according to this invention.
Now referring to the figures of the accompanying drawing, waste heat recovery boiler (1) and economizer (2) for dust laden flue gases comprises number of slender tubes (3) arranged one above the other vertically. Water (8) is inside the said tubes (3) and flue gas (9) outside the said tube (3). The each of the said Tubes (3) in one row have a common header (5) at the top and bottom forming one cassette of that row. Many such cassettes are kept adjacent to each other forming square matrix of the tubes (3). All these said tubes (3) are supported only at the top so that they are freely hanging under self-weight of the boiler / economizer. This eliminates possibilities of the said tube (3) buckling due to thermal expansion. Intermediate horizontal supports (6) are provided between the gaps at regular intervals of about 1.5 meter. These supports prevent the bending of the said tubes (3). Also vibrators / hammers (7) can be given on these supports so that the removal of dust from the tube surface can be done easily. The top face of these said supports (6) is given inclination of about 60° with respect to horizontal. Hence powder falls freely from those

and doesn't accumulate on the top face of supports. The hot gases with dust and the like enter the system from the top and move downwards.Velocity of the gases is kept lower so that dust powder separates by gravity and pressure drop across the system remains minimum & keeps exhaust gas handling fan power to minimum.
1. The "Co-current down flow arrangement" for air and dust greatly enhances the movement of separated dust to the lower portion without accumulation or deposition in the system, minimizing / eliminating fouling or choking. The gravitational flow of the powder also eliminates additional power requirement for its conveying. The steam (10) generated is stored in a steam drum (4) having various safety mountings and controls. The system is fully automatic. 2.
Automation 4s either based on preprogrammed on & off cycle timing of vibrators / Hammers (7) or it works on gas pressure drop across the said boiler (1).
The automatic system working on Flue Gas Pressure is as follows:
A separate differential gas pressure switch (not shown in the figure) is provided across the boiler (1) & economizer (2). If the pressure drop increases beyond desired set point (set level) the vibrators / hammers (7) will work "continuously" or "continuously cyclically" till pressure drop comes back within desired limit.
Powder dislodged from the said tube (3) surfaces due to hammering / vibrations fall freely downwards without obstruction through uniform flue gas (9) passage.
Details of components in figure 1 and 2 :-

Details of components in figure 1 and 2 :-
Boiler 1,
Economizer 2,
Slender tubes 3,
Steam drum 4,
Header 5,
Intermediate horizontal supports 6,
Vibrators / hammers 7,
Water 8,
Fiue gas 9,
Steam 10
The salient features are as follows:
Boilers and economizers are water tube type with tubes hanging vertically. Water is inside the tubes and flue gas outside the tube. Tubes have intermediate supports at about 1.5-meter pitch, which keep the tubes straight. The top face of intermediate supports are given 60° slant angle from horizontal, so that dust cake dislodged from tube surface does not accumulate on these supports but slides down easily on the slant. The downwards flow of the fiue gases and gravity fall of dust cake greatly and easily "co-operate" each other to reach bottom with following advantages:-
A) The flue gas velocities can be much lower than pneumatic conveying velocities. This benefits in -
Lower frictional pressure loss in flue gas flow saving energy in fan power required.
Gravitational energy used for dust. Hence fiue gas doesn't have to be imparted additional energy, otherwise

pneumatic conveying, saving pneumatic conveying energy.
This greatly increases net electrical energy exported for external use.
B) Vertical downward "parallel to heat transfer area" flue gas flow with free flowing gravity force driven dust cake eliminates any possibility of re-deposition of dust on the tubes.
Due to this the boiler heat recovery is very effective and tube fouling (which reduces effectiveness of heat transfer area) is lowest.
If the fouling were to be high, then the heating surface required would have to be much higher. Increase in boiler heating surface, increases boiler steel requirement, increases dry and operating wet of boiler. The increased boiler weight increases structural support steel quantities.
All these greatly increase initial cost (capital cost) of the equipment.
Therefore, the clean surfaces means lower first cost, also if boiler has higher heating surface it has higher flue gas pressure drop (flue gas frictional resistance). So fan consumes more power reducing net power exported from heat recovery co-generation system.
Therefore excessive fouling of 'Heat Transfer Surface' will reduce the commercial viability of the project.
Mechanical vibrators or hammers (8) are provided to dislodge the powder deposited on the surface. 3. All the tube headers are supported at the top only so that -
a) Tubes remain straight avoiding buckling.
b) Tubes are free to expand thermally which leaves the system without any strain.
c) Tubes remain in tension by force equal to gravity weight of the boiler, giving better life. Since metal has higher tensile

strength than compressive strength.
Advantages of the present invention :
1. Low pressure drop on the flue-gas, conserving fan power.
2. Rue gas and dislodged dust both move in the downward direction resulting in the seif-cieaning process.
3. Automatic vibrators / mechanicai hammers disiodge the settied powder easily.
4. Free hanging tube design under seif-weight prevents bending / buckiing of the tubes.
5. Dust deposition and fouiing being avoided, heat transfer effectiveness is ensured.

I CLAIM :-
1. A waste heat recovery boiler and economizer for dust laden flue gases comprising water tube type boiler and economizer made with slender tubes arranged one above the other; the said tubes in one row having the common header at the top and bottom forming one cassette of the row; plurality of such said cassettes are kept adjacent to each other forming square matrix of the tubes; all such tubes are supported at the top to hang freely; intermediate horizontal supports are provided between the tubes at regular interval to prevent bending of the said tubes; top face of the said intermediate horizontal supports is given inclination of about 60° slant with respect to the horizontal so that dust falling on the said supports falls freely and doesn't accumulate or deposit on the same ensuring higher heat transfer effective.
2. A waste heat recovery boiler and economizer for dust laden flue gases as claimed in claim 1 wherein the said intermediate horizontal supports are provided with automatic vibrators/ mechanical hammers to dislodge the settled powder.
3. A waste heat recovery boiler and economizer for dust laden flue gases as claimed in claim 1 and 2 along with the steam drum to collect the generated steam.
4. A waste heat boiler and economizer for dust laden flue gases as claimed in claim 1 to 3 and as herein described with reference to the figures of the accompanying drawings.
Dated this 6th Day of Jutte,2001

Documents:

544-mum-2001-abstract(26-08-2004).doc

544-mum-2001-abstract(26-08-2004).pdf

544-mum-2001-abstract(26-8-2004).pdf

544-mum-2001-abstract(granted)-(17-1-2006).pdf

544-mum-2001-cancelled pages(26-08-2004).pdf

544-mum-2001-claims(13-6-2001).pdf

544-mum-2001-claims(amended)-(26-8-2004).pdf

544-mum-2001-claims(granted)-(17-1-2006).pdf

544-mum-2001-claims(granted)-(26-08-2004).doc

544-mum-2001-claims(granted)-(26-08-2004).pdf

544-mum-2001-correspondence(26-08-2004).pdf

544-mum-2001-correspondence(ipo)-(17-01-2006).pdf

544-mum-2001-correspondence(ipo)-(17-2-2006).pdf

544-mum-2001-description(complete)-(13-6-2001).pdf

544-mum-2001-description(granted)-(17-1-2006).pdf

544-mum-2001-drawing(13-6-2001).pdf

544-mum-2001-drawing(26-08-2004).pdf

544-mum-2001-drawing(granted)-(17-1-2006).pdf

544-mum-2001-form 1(13-06-2001).pdf

544-mum-2001-form 16(13-7-2009).pdf

544-mum-2001-form 19(09-06-2003).pdf

544-mum-2001-form 2(complete)-(13-6-2001).pdf

544-mum-2001-form 2(granted)-(17-1-2006).pdf

544-mum-2001-form 2(granted)-(26-08-2004).doc

544-mum-2001-form 2(granted)-(26-08-2004).pdf

544-mum-2001-form 2(title page)-(complete)-(13-6-2001).pdf

544-mum-2001-form 2(title page)-(granted)-(17-1-2006).pdf

544-mum-2001-general power of attorney(13-7-2009).pdf

544-mum-2001-power of authority(13-06-2001).pdf

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Patent Number

197768

Indian Patent Application Number

544/MUM/2001

PG Journal Number

41/2007

Publication Date

12-Oct-2007

Grant Date

17-Jan-2006

Date of Filing

13-Jun-2001

Name of Patentee

ASHOK DATTATRAYA ATRE

Applicant Address

'PUSHPA HEIGHTS', 1ST FLOOR BIBWEWADI CORNER, PUNE-413 117, MAHARASHTRA STATE, INDIA.

Inventors:

#	Inventor's Name	Inventor's Address
1	ASHOK DATTATRAYA ATRE	'PUSHPA HEIGHTS', 1ST FLOOR BIBWEWADI CORNER, PUNE-413117, MAHARASHTRA STATE, INDIA.

PCT International Classification Number

N/A

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA