Title of Invention	AN IMPROVED WEAR PROTECTION DEVICE AND A METHOD FOR HANGER TUBES IN BUBBLING FLUIDIZED BED COMBUSTION (BFBC) BOILERS
Abstract	Accordingly, there is provided an improved method of strap support in hanger tube for wear protection in BFBC boilers comprising a hot air distributor plate disposed at the bottom boundary of the combustor enclosed by a membrane, said plate having a plurality of air nozzles, a hot air source for continuous supply of hot air through said nozzles into the fluidized bed, a first super heater coil immersed in the bed of the boiler; a second super heater coil above the bed supported by a plurality of hanger tubes; and a tube assembly comprising a tube, straps and vertical sleeves fitted over the tube.

Title of Invention

AN IMPROVED WEAR PROTECTION DEVICE AND A METHOD FOR HANGER TUBES IN BUBBLING FLUIDIZED BED COMBUSTION (BFBC) BOILERS

Abstract

Accordingly, there is provided an improved method of strap support in hanger tube for wear protection in BFBC boilers comprising a hot air distributor plate disposed at the bottom boundary of the combustor enclosed by a membrane, said plate having a plurality of air nozzles, a hot air source for continuous supply of hot air through said nozzles into the fluidized bed, a first super heater coil immersed in the bed of the boiler; a second super heater coil above the bed supported by a plurality of hanger tubes; and a tube assembly comprising a tube, straps and vertical sleeves fitted over the tube.

Full Text	- 2- TntE i ^IMPROVED MEHTOP OF STRAP SUPPORT IH HANGER TUBK OF BFBC BOILERS ADAPTABLE TO WEAR PROTECTIOW'. FIELPOFTHEINVEHTIQM The pre^nt invention relates to an improved method of strap support of haiger tubes in Bubbling fiuidized bed combustion boilers. (BFBC). More particularly, the pre^nt Invention relates to an Improved method of strap support In hanger tubes for wear protection in BFBC boilers. BACKQRQVNP Of THE INVENTIPH The BFBC ts an environment friendly and efficient system of burning various grades of fuels. The fuel bums between 700-900 deg C. This temperature ensures that Nox is not formed. Sortent In the form of limestone Is added to capture the sulphur in the fuel thereby preventing the formation of Sox. The principle heat ti'ansfer surges like evaporator and super heater are immersed in the fiuidized bed. The primary air of combustion is directed through the bed at a pre determined velocity, at which the bed behaves like fluid and effective heat transfer takes place due to fluidization. Hanger tubes constituting evaporator tubes are used for supporting Super heater colls inside the fijmace of the boiler. Typical arrangement is shown in Eg 1. Two horizontal straps are used to support the colls along with the vertical hanger tijbe. The arrangement is such that it supports the coils as well as allows for -3- thermal expansions to be accommodated. It was observed in many boilers that the horizontal straps were continuously rubbing against the hanger tube and causing feilure of hanger tube due to wear. OBJECTS OF THE INVENTION It is therefore, an object of the present invention to propose an Improved method of strap support In hanger tubes for wear protection which protects the hanger tubes from rubbing due to thermal expansion of hori^ntal straps. An another object of the invention is to propose an Improved method of strap support in hanger tubes for wear protection which efficientiy protects the hanger tubes from rubbing due to thermal movements of straps and thereby enhances the life of tiie hanger tubes. A further object of the present invention is to propose an improved method of strap support in hanger tube for wear protection which efficientiy protects the hanger tubes ftom rubbing due to thermal movement of straps which enables optimized routing of the hanger tubes. A still further object of the present invention is to propose an improved method of strap support In hanger tube for wear protection which efficientiy protects the hanger tubes fiiom rubbing due to thermal movement of straps which makes the furnace further compact. -4- SUMMARY OF THE IHVENTIOW Accordingly, there is provided an improved method of strap support In hanger tube for wear protection in Bf=BC boilers comprising a hot air distributor plate disposed at the bottom boundary of the combustor enclosed by a membrane, said plate having a plurality of air nozzles, a hot air source for continuous supply of hot air through said nozzles Into the fluidized bed, a first super heater coil immersed In the bed of the boiler; a second super heater coil above the bed supported by a plurality of hanger tubes; and a tube assembly comprising a tube, straps and vertical sleeves fitted over the tube. BRIEF PESCRIPTIOW OF THE ACCOMPAMYIHG DRAWIHGS Rgure 1 - shows a typical arrangement of hanger taibes in a BFBC boiler, Figure 2 - shows a cross sectional view of a strap support tube used in prior art. Rgure 3 - shows a vertical sleeve fitted on to a hanger tube. DETAILED DESCRIPTION OF A PREFERRED EMEBODIMENT OF THE With the above and other objectives in view, the present invention provides an alternative method of wear protection of hanger tube. The present invention -5- nelafces to a Bfec boiter to overcome the above said drawbacks. It has been the endeavor of the applicant to develop alternate ways to avoid wears. The present invention provides an improved and cost effective device for wear ptx>tect3on. Accordingly to present invention, vertical sleeve are designed to form a ring over a tube (11) so that they form a protective layer (Rg 3). The type of tube used has high wear resistant properties. Further it is tested with suitable erosion tests t» determine the suitability for the intended woridng atmosphere. Having ensured so the sleeve material is selected. T^e sleeve is mounted on t^e hanger tube after providing suitable slots for projection of the support lugs. The strap arrangement is then assembled over it supporting the SH coils. The sleeve prevents direct rubbing of straps against the tube. Thus the wear of the hanger tube is prevented. A hot^ir distributor plate (1) is arranged fixedly on the boundary wall of the BFBC boiler by a membrane (2). The plate (1) is having a number of air-injecting nozzles (7). Hot air form a source is continuously passed to tjie fluidized bed (8) of the boiler via the nozzles (7). One each heater coil (3, 4) is placed inside the bed (8) and above the bed (8). The second heater coil (4) is supported by a plurality of hanger tubes (5). Instead of direct strap supports (9) as of the prior art, a vertical sleeve (6) Is mounted over a tube (11) to entirely cover the tube (11) portion where the straps rub against it thereby forming a assembly (10). The tube assembly (10) prevents the hanger tubes (5) from getting wear by the thermal movement of the straps thereby protecting the hanger tubes (5) from feilure. Accordingly, there is provided an improved method of strap support in hanger tube for wear protection in BFBC boilers comprising a hot air distributor plate disposed at the bottom boundary of the combustor enclosed by a membrane, said plate having a plurality of air nozzles, a hot air source for continuous supply of hot air through said nozzles into the fluidized bed, a first super heater coil immersed in the bed of the boiler; a second super heater coil above the bed supported by a plurality of hanger tubes; and a tube assembly comprising a tube, straps and vertical sleeves fitted over the tube.

Full Text

- 2-
TntE i ^IMPROVED MEHTOP OF STRAP SUPPORT IH HANGER TUBK
OF BFBC BOILERS ADAPTABLE TO WEAR PROTECTIOW'.
FIELPOFTHEINVEHTIQM
The pre^nt invention relates to an improved method of strap support of haiger
tubes in Bubbling fiuidized bed combustion boilers. (BFBC). More particularly, the
pre^nt Invention relates to an Improved method of strap support In hanger
tubes for wear protection in BFBC boilers.
BACKQRQVNP Of THE INVENTIPH
The BFBC ts an environment friendly and efficient system of burning various
grades of fuels. The fuel bums between 700-900 deg C. This temperature
ensures that Nox is not formed. Sortent In the form of limestone Is added to
capture the sulphur in the fuel thereby preventing the formation of Sox. The
principle heat ti'ansfer surges like evaporator and super heater are immersed in
the fiuidized bed. The primary air of combustion is directed through the bed at a
pre determined velocity, at which the bed behaves like fluid and effective heat
transfer takes place due to fluidization.
Hanger tubes constituting evaporator tubes are used for supporting Super heater
colls inside the fijmace of the boiler. Typical arrangement is shown in Eg 1.
Two horizontal straps are used to support the colls along with the vertical hanger
tijbe. The arrangement is such that it supports the coils as well as allows for

-3-
thermal expansions to be accommodated. It was observed in many boilers that
the horizontal straps were continuously rubbing against the hanger tube and
causing feilure of hanger tube due to wear.
OBJECTS OF THE INVENTION
It is therefore, an object of the present invention to propose an Improved
method of strap support In hanger tubes for wear protection which protects the
hanger tubes from rubbing due to thermal expansion of hori^ntal straps.
An another object of the invention is to propose an Improved method of strap
support in hanger tubes for wear protection which efficientiy protects the hanger
tubes from rubbing due to thermal movements of straps and thereby enhances
the life of tiie hanger tubes.
A further object of the present invention is to propose an improved method of
strap support in hanger tube for wear protection which efficientiy protects the
hanger tubes ftom rubbing due to thermal movement of straps which enables
optimized routing of the hanger tubes.
A still further object of the present invention is to propose an improved method
of strap support In hanger tube for wear protection which efficientiy protects the
hanger tubes fiiom rubbing due to thermal movement of straps which makes the
furnace further compact.

-4-
SUMMARY OF THE IHVENTIOW
Accordingly, there is provided an improved method of strap support In hanger
tube for wear protection in Bf=BC boilers comprising a hot air distributor plate
disposed at the bottom boundary of the combustor enclosed by a membrane,
said plate having a plurality of air nozzles, a hot air source for continuous supply
of hot air through said nozzles Into the fluidized bed, a first super heater coil
immersed In the bed of the boiler; a second super heater coil above the bed
supported by a plurality of hanger tubes; and a tube assembly comprising a
tube, straps and vertical sleeves fitted over the tube.
BRIEF PESCRIPTIOW OF THE ACCOMPAMYIHG DRAWIHGS
Rgure 1 - shows a typical arrangement of hanger taibes in a BFBC boiler,
Figure 2 - shows a cross sectional view of a strap support tube used in prior art.
Rgure 3 - shows a vertical sleeve fitted on to a hanger tube.
DETAILED DESCRIPTION OF A PREFERRED EMEBODIMENT OF THE
With the above and other objectives in view, the present invention provides an
alternative method of wear protection of hanger tube. The present invention

-5-
nelafces to a Bfec boiter to overcome the above said drawbacks. It has been the
endeavor of the applicant to develop alternate ways to avoid wears.
The present invention provides an improved and cost effective device for wear
ptx>tect3on. Accordingly to present invention, vertical sleeve are designed to
form a ring over a tube (11) so that they form a protective layer (Rg 3).
The type of tube used has high wear resistant properties. Further it is tested with
suitable erosion tests t» determine the suitability for the intended woridng
atmosphere. Having ensured so the sleeve material is selected.
T^e sleeve is mounted on t^e hanger tube after providing suitable slots for
projection of the support lugs. The strap arrangement is then assembled over it
supporting the SH coils. The sleeve prevents direct rubbing of straps against the
tube. Thus the wear of the hanger tube is prevented.
A hot^ir distributor plate (1) is arranged fixedly on the boundary wall of the
BFBC boiler by a membrane (2). The plate (1) is having a number of air-injecting
nozzles (7). Hot air form a source is continuously passed to tjie fluidized bed (8)
of the boiler via the nozzles (7). One each heater coil (3, 4) is placed inside the
bed (8) and above the bed (8). The second heater coil (4) is supported by a
plurality of hanger tubes (5). Instead of direct strap supports (9) as of the prior
art, a vertical sleeve (6) Is mounted over a tube (11) to entirely cover the tube
(11) portion where the straps rub against it thereby forming a assembly (10).
The tube assembly (10) prevents the hanger tubes (5) from getting wear by the
thermal movement of the straps thereby protecting the hanger tubes (5) from
feilure.

Accordingly, there is provided an improved method of strap support in hanger
tube for wear protection in BFBC boilers comprising a hot air distributor plate
disposed at the bottom boundary of the combustor enclosed by a membrane,
said plate having a plurality of air nozzles, a hot air source for continuous supply
of hot air through said nozzles into the fluidized bed, a first super heater coil
immersed in the bed of the boiler; a second super heater coil above the bed
supported by a plurality of hanger tubes; and a tube assembly comprising a
tube, straps and vertical sleeves fitted over the tube.

Documents:

http://ipindiaonline.gov.in/patentsearch/GrantedSearch/viewdoc.aspx?id=748uZt6+tGpnjtAF77CCUQ==&loc=wDBSZCsAt7zoiVrqcFJsRw==

« Previous Patent

Next Patent »

Patent Number

271969

Indian Patent Application Number

536/KOL/2008

PG Journal Number

12/2016

Publication Date

18-Mar-2016

Grant Date

11-Mar-2016

Date of Filing

18-Mar-2008

Name of Patentee

BHARAT HEAVY ELECTRICALS LIMITED

Applicant Address

REGIONAL OPERATIONS DIVISION (ROD), PLOT NO: 9/1, DJ BLOCK 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	SUNDARRAJAN PRABHAKAR	INDIA
2	STEPHEN LAWRENCE RAJ	INDIA

PCT International Classification Number

F22B37/20; F22G7/14; F22B37/00

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA