Title of Invention	AN IMPROVED THERMOCOUPLE BASED FIRE SENSING DEVICE FOR REGENERATIVE AIR PREHEATER
Abstract	The present invention relates to an improved thermocouple based fire sensing device for regenerative air preheater comprising a plurality of individual thermocouple assemblies (06) mounted at substantially spaced at air outlet and gas outlet paths of the air preheater (10) and the thermocouple assemblies (06) sensing the temperature inside the preheater and generating signals and the generated signals are transferred to a digital data control and monitoring information means (08) via cables (07); characterized in that digital data control and monitoring information means processes the transmitted signals representing the sensed temperature value and compares the data with respect to a preset temperature value and generates a fire alarm signal in cases the data relating to sensed temperature by the thermocouple assemblies exceeds preset temperature and the fire alarm signal raises in alarm in unit control board (09).

Title of Invention

AN IMPROVED THERMOCOUPLE BASED FIRE SENSING DEVICE FOR REGENERATIVE AIR PREHEATER

Abstract

The present invention relates to an improved thermocouple based fire sensing device for regenerative air preheater comprising a plurality of individual thermocouple assemblies (06) mounted at substantially spaced at air outlet and gas outlet paths of the air preheater (10) and the thermocouple assemblies (06) sensing the temperature inside the preheater and generating signals and the generated signals are transferred to a digital data control and monitoring information means (08) via cables (07); characterized in that digital data control and monitoring information means processes the transmitted signals representing the sensed temperature value and compares the data with respect to a preset temperature value and generates a fire alarm signal in cases the data relating to sensed temperature by the thermocouple assemblies exceeds preset temperature and the fire alarm signal raises in alarm in unit control board (09).

Full Text	FIELD OF THE INVENTION: The invention relates to an improved thermocouple based fire sensing device for Regenerative Air Preheater. BACKGROUND OF THE INVENTION: Rotary regenerative Air Preheaters are used in Thermal power boilers/Industrial applications to transfer the heat from the flue gas leaving the boiler/furnace to the entering combustion air through specially formed heat transfer surfaces housed inside a rotor which rotates alternatively in air and gas streams. Air Preheaters fire start with the ignition of combustible deposits in the heat transfer surface. The majority of fires occur in Air Preheaters during start up of the boilers with oil. An unusual increase in terminal temperatures that is, air outlet or gas outlet indicates a fire has started in Air Preheater. Hence, unusual increase in air leaving/gas leaving temperatures is to be monitored to detect a fire situation in an Air Preheater. The Air Preheater fire sensing device consists of two numbers multi point thermocouple pipe assemblies, one micro processor based temperature scanner panel and inter connecting cables. The number of points in a multi point thermocouple pipe assembly varies from 4 to 9 depending on the Air Preheater diameter. The multi point thermocouple pipe assemblies are mounted in the APH connecting plate ducts at gas outlet and air outlet to measure the gas leaving and air leaving temperatures. The signals from the multi point thermocouple pipe assemblies are connected to a micro processor based temperature scanner panel located near the APH through cables. The temperature scanner panel processes these signals and initiates a fire alarm signal if the measured temperature is more than the set value. This fire alarm signal is further connected to UCB (Unit Control Board) through cables for generation of the fire alarm. The thermocouple pipe assemblies are lengthier and make mounting and withdrawal difficult Also, the tips of the thermocouples get damaged while mounting and withdrawal. Lengthy thermocouple pipe assemblies foul with Moor support beams during mounting and withdrawal. The micro processor based temperature scanner panel located near the Air preheater does not perform satisfactorily due to high dusty environment. An US 2003112140 (A1) patent entitled "Fuel cell system with a detection system for fire or elevated temperatures", the abstract of which states a fuel cell system includes a fuel cell stack with single fuel cells stacked together in a fuel cell housing and a detection system for fire or elevated temperatures. The detection system may include a monitoring system; a sensor unit that detects fire or elevated temperatures inside said fuel cell housing; and a voltage or current source. A GB 1397951 (A) 1397951 Temperature alarms BABCOCK & WILCOX Ltd 22 May 1972 [21 May 1971] 24053/72 Heading G4N [Also in Divisions F4 and H1] patent entitled "Rotary air heaters", the abstract of which discloses in an air heater (e.g. a thermal regenerator) sudden local rise in temperature in a rotor is sensed via the air stream by one or more temperature responsive means and an electrical signal is thereby applied to an electrical circuit via an amplifier A. A relay R4 is energized on receipt of a first signal from the member 9, relays R5 and R2 are energized on receipt of a second signal from the member 9, and a relay R3 is energized on receipt of a third signal from the member 9 to operate a warning device AV. If no subsequent signals are received after the first or second signals the electrical circuit is de-energized until another "first" signal is received. After the warning device AV has been actuated the alarm signal persists until the circuit has been restored to its original condition by manual actuation of contacts B1, B2, B3 and B4. The preferred heat sensing means comprises a series of thermocouples 10 which react almost at once to any temperature change alternating along a member 9 with thermocouples 11 less sensitive to a sudden temperature change. An EP 0310233 (A2) patent entitled "Diagnostic control systems with alarm procedure", the abstract of which discloses a combustion control system includes a sensor assembly and a process controller, the sensor assembly including sensors for providing output signals indicative of process variables, and the process controller responding to the output signals to maintain a desired operation of the process. The process controller continuously monitors parameters of the sensors and provides alarms whenever any of these parameters deviate from setpoint values, the process controller automatically prioritizing these alarms to provide a display of only the most relevant alarms. A housing enclosing the processor controller provides electromagnetic and/or radio frequency interference (EMI/RFI) shielding of the process controller including attenuation and absorption of EMI/RFI energy. A DE 4127004 (A1) patent entitled "Early fire detection arrangement - contains combination of sensors, microprocessor-controlled signal evaluation unit, fuzzy logic or neural network to avoid false alarms", the abstract of which states the arrangement for the early detection of fires contains a combination of several sensors for different materials. The combination contains gas sensors and others, such as moisture of temperature sensors. An arrangement generates a gas with defined characteristics. A microprocessor-controlled signal evaluation unit is connected to the sensors and an alarm generator. The signal evaluation unit operates with fuzzy logic. The sensor signals can be processed in parallel by a neural network built in hardware or software form. USE/ADVANTAGE - Arrangement is improved to ensure reliable early detection of fires whilst preventing false alarms caused by tolerable gas and temperature triggering. OBJECTS OF THE INVENTION It is therefore an object of the invention to propose an improved fire sensing device for regenerative air preheater which eliminates the disadvantages of the prior art. Another object of the invention to propose an improved fire sensing device for regenerative air preheater which adapts individual thermocouple assemblies to ensure their easy mounting and dismounting including avoidance of fouling with other structural members. A further object of the invention to propose an improved fire sensing device for regenerative air preheater in which configuration of the thermocouple assemblies are selected such that frequent tip damages can be eliminated. A still further object of the Invention to propose an improved fire sensing device for regenerative air preheater which is capable of providing an effective monitoring and control performance even under high dusty envirorment SUMMARY OF THE INVENTION: The present invention relates to an improved thermocouple based fire sensing device for regenerative air preheater comprising a plurality of individual thermocouple assemblies mounted at substantially spaced at air outlet and gas outlet paths of the air preheater and the thermocouple assemblies sensing the temperature inside the preheater and generating signals and the generated signals are transferred to a digital data control and monitoring information means via cables; characterized in that digital data control and monitoring information means processes the transmitted signals representing the sensed temperature value and compares the data with respect to a preset temperature value and generates a fire alarm signal in cases the data relating to sensed temperature by the thermocouple assemblies exceeds preset temperature and the fire alarm signal raises in alarm in unit control board. BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS: Figure 1 (a) shows the prior art device including arrangement of the thermocouple pipe assembly with local control panel. Figure 1 (b) shows the improved device according to the invention including arrangement of individual thermocouples connected to a DDCMIM in a UCB. Figure 2 (a) shows the assembly of thermocouple pipe in a device according to the prior art Figure 2 (b) shows the individual thermocouple assembly in an improved device according to the present invention. DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION: Prior art arrangement as shown in fig 1 (a) comprises at least two numbers of multi point thermocouple pipe assemblies (02) located in air outlet and gas outlet ducts of a regenerative air preheater (10). The signals from the pipe assemblies (02) are transmitted to a micro processor based temperature scanner panel (01) mounted locally near the air preheater (10) through a first set of cables (03). The fire alarm signal from the scanner panel (01) is connected to a UCB (05) through a second set of cables (04). According to the invention, as shown in fig 1(b), individual thermocouple assemblies (06) are mounted in the centre sections of the Air Preheater (10) at air outlet and gas outlet paths. Signals from the thermocouples (06) are connected through cables (07) to a DDCMIM (8) in UCB (09). The signals are processed in the DDCMIM (08) at the UCB(09) and a fire alarm is generated if the measured temperature is more than the set value. Signal processing and fire alarm generation in the DDCMIM at the UCB is more reliable than the micro processor based temperature scanner panel (01) located in the dusty environment near the Air preheater (10). Individual thermocouples (06) as shown In fig 2 (b) is short in length compared to the multi point thermocouple pipe assemblies (02) as shown in fig 2 (a). The performance of the device is enhanced as the signal processing Is done in the DDCMIM (08) at the UCB (09). The initial cost of the device is reduced. WE CLAIM:- 1. An improved thermocouple based fire sensing device for regenerative air preheater comprising:- - a plurality of individual thermocouple assemblies (06) mounted at substantially spaced at air outlet and gas outlet paths of the air preheater (10); - the thermocouple assemblies (06) sensing the temperature inside the preheater and generating signals; - the generated signals are transferred to a digital data control and monitoring information means (08) via cables (07); - characterized in that digital data control and monitoring information means processes the transmitted signals representing the sensed temperature value and compares the data with respect to a preset temperature value and generates a fire alarm signal in cases the data relating to sensed temperature by the thermocouple assemblies exceeds preset temperature and the fire alarm signal raises in alarm in unit control board (09). 2. An improved thermocouple based fire sensing device for regenerative air preheater as substantially described and illustrated herein with reference to the accompanying drawings. ABSTRACT AN IMPROVED THERMOCOUPLE BASED FIRE SENSING DEVICE FOR REGENERATIVE AIR PREHEATER The present invention relates to an improved thermocouple based fire sensing device for regenerative air preheater comprising a plurality of individual thermocouple assemblies (06) mounted at substantially spaced at air outlet and gas outlet paths of the air preheater (10) and the thermocouple assemblies (06) sensing the temperature inside the preheater and generating signals and the generated signals are transferred to a digital data control and monitoring information means (08) via cables (07); characterized in that digital data control and monitoring information means processes the transmitted signals representing the sensed temperature value and compares the data with respect to a preset temperature value and generates a fire alarm signal in cases the data relating to sensed temperature by the thermocouple assemblies exceeds preset temperature and the fire alarm signal raises in alarm in unit control board (09).

Full Text

FIELD OF THE INVENTION:
The invention relates to an improved thermocouple based fire sensing device for
Regenerative Air Preheater.
BACKGROUND OF THE INVENTION:
Rotary regenerative Air Preheaters are used in Thermal power boilers/Industrial
applications to transfer the heat from the flue gas leaving the boiler/furnace to
the entering combustion air through specially formed heat transfer surfaces
housed inside a rotor which rotates alternatively in air and gas streams.
Air Preheaters fire start with the ignition of combustible deposits in the heat
transfer surface. The majority of fires occur in Air Preheaters during start up of
the boilers with oil. An unusual increase in terminal temperatures that is, air
outlet or gas outlet indicates a fire has started in Air Preheater. Hence, unusual
increase in air leaving/gas leaving temperatures is to be monitored to detect a
fire situation in an Air Preheater.

The Air Preheater fire sensing device consists of two numbers multi
point thermocouple pipe assemblies, one micro processor based
temperature scanner panel and inter connecting cables. The number
of points in a multi point thermocouple pipe assembly varies from 4
to 9 depending on the Air Preheater diameter. The multi point
thermocouple pipe assemblies are mounted in the APH connecting
plate ducts at gas outlet and air outlet to measure the gas leaving
and air leaving temperatures. The signals from the multi point
thermocouple pipe assemblies are connected to a micro processor
based temperature scanner panel located near the APH through
cables. The temperature scanner panel processes these signals and
initiates a fire alarm signal if the measured temperature is more than
the set value. This fire alarm signal is further connected to UCB (Unit
Control Board) through cables for generation of the fire alarm.
The thermocouple pipe assemblies are lengthier and make mounting
and withdrawal difficult Also, the tips of the thermocouples get
damaged while mounting and withdrawal. Lengthy thermocouple
pipe assemblies foul with Moor support beams during mounting and
withdrawal. The micro processor based temperature scanner panel
located near the Air preheater does not perform satisfactorily due to
high dusty environment.

An US 2003112140 (A1) patent entitled "Fuel cell system with a detection system
for fire or elevated temperatures", the abstract of which states a fuel cell system
includes a fuel cell stack with single fuel cells stacked together in a fuel cell
housing and a detection system for fire or elevated temperatures. The detection
system may include a monitoring system; a sensor unit that detects fire or
elevated temperatures inside said fuel cell housing; and a voltage or current
source.
A GB 1397951 (A) 1397951 Temperature alarms BABCOCK & WILCOX Ltd 22
May 1972 [21 May 1971] 24053/72 Heading G4N [Also in Divisions F4 and H1]
patent entitled "Rotary air heaters", the abstract of which discloses in an air
heater (e.g. a thermal regenerator) sudden local rise in temperature in a rotor is
sensed via the air stream by one or more temperature responsive means and an
electrical signal is thereby applied to an electrical circuit via an amplifier A. A
relay R4 is energized on receipt of a first signal from the member 9, relays R5
and R2 are energized on receipt of a second signal from the member 9, and a
relay R3 is energized on receipt of a third signal from the member 9 to operate a
warning device AV. If no subsequent signals are received after the first or second
signals the electrical circuit is de-energized until another "first" signal is received.
After the warning device AV has been actuated the alarm signal persists until the
circuit has been restored to its original condition by manual actuation of contacts
B1, B2, B3 and B4. The preferred heat sensing means comprises a series of
thermocouples 10 which react almost at once to any temperature change
alternating along a member 9 with thermocouples 11 less sensitive to a sudden
temperature change.
An EP 0310233 (A2) patent entitled "Diagnostic control systems with alarm
procedure", the abstract of which discloses a combustion control system includes

a sensor assembly and a process controller, the sensor assembly including
sensors for providing output signals indicative of process variables, and the
process controller responding to the output signals to maintain a desired
operation of the process. The process controller continuously monitors
parameters of the sensors and provides alarms whenever any of these
parameters deviate from setpoint values, the process controller automatically
prioritizing these alarms to provide a display of only the most relevant alarms. A
housing enclosing the processor controller provides electromagnetic and/or radio
frequency interference (EMI/RFI) shielding of the process controller including
attenuation and absorption of EMI/RFI energy.
A DE 4127004 (A1) patent entitled "Early fire detection arrangement - contains
combination of sensors, microprocessor-controlled signal evaluation unit, fuzzy
logic or neural network to avoid false alarms", the abstract of which states the
arrangement for the early detection of fires contains a combination of several
sensors for different materials. The combination contains gas sensors and others,
such as moisture of temperature sensors. An arrangement generates a gas with
defined characteristics. A microprocessor-controlled signal evaluation unit is
connected to the sensors and an alarm generator. The signal evaluation unit
operates with fuzzy logic. The sensor signals can be processed in parallel by a
neural network built in hardware or software form. USE/ADVANTAGE -
Arrangement is improved to ensure reliable early detection of fires whilst
preventing false alarms caused by tolerable gas and temperature triggering.

OBJECTS OF THE INVENTION
It is therefore an object of the invention to propose an improved fire
sensing device for regenerative air preheater which eliminates the
disadvantages of the prior art.
Another object of the invention to propose an improved fire sensing
device for regenerative air preheater which adapts individual
thermocouple assemblies to ensure their easy mounting and
dismounting including avoidance of fouling with other structural
members.
A further object of the invention to propose an improved fire sensing
device for regenerative air preheater in which configuration of the
thermocouple assemblies are selected such that frequent tip
damages can be eliminated.
A still further object of the Invention to propose an improved fire
sensing device for regenerative air preheater which is capable of
providing an effective monitoring and control performance even
under high dusty envirorment

SUMMARY OF THE INVENTION:
The present invention relates to an improved thermocouple based fire sensing
device for regenerative air preheater comprising a plurality of individual
thermocouple assemblies mounted at substantially spaced at air outlet and gas
outlet paths of the air preheater and the thermocouple assemblies sensing the
temperature inside the preheater and generating signals and the generated
signals are transferred to a digital data control and monitoring information
means via cables; characterized in that digital data control and monitoring
information means processes the transmitted signals representing the sensed
temperature value and compares the data with respect to a preset temperature
value and generates a fire alarm signal in cases the data relating to sensed
temperature by the thermocouple assemblies exceeds preset temperature and
the fire alarm signal raises in alarm in unit control board.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS:
Figure 1 (a) shows the prior art device including arrangement of the
thermocouple pipe assembly with local control panel. Figure 1 (b)
shows the improved device according to the invention including
arrangement of individual thermocouples connected to a DDCMIM in
a UCB.
Figure 2 (a) shows the assembly of thermocouple pipe in a device
according to the prior art
Figure 2 (b) shows the individual thermocouple assembly in an
improved device according to the present invention.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF
THE INVENTION:
Prior art arrangement as shown in fig 1 (a) comprises at least two
numbers of multi point thermocouple pipe assemblies (02) located in
air outlet and gas outlet ducts of a regenerative air preheater (10).
The signals from the pipe assemblies (02) are transmitted to a micro
processor based temperature scanner panel (01) mounted locally
near the air preheater (10) through a first set of cables (03). The fire
alarm signal from the scanner panel (01) is connected to a UCB (05)
through a second set of cables (04).

According to the invention, as shown in fig 1(b), individual
thermocouple assemblies (06) are mounted in the centre sections of
the Air Preheater (10) at air outlet and gas outlet paths. Signals from
the thermocouples (06) are connected through cables (07) to a
DDCMIM (8) in UCB (09). The signals are processed in the DDCMIM
(08) at the UCB(09) and a fire alarm is generated if the measured
temperature is more than the set value. Signal processing and fire
alarm generation in the DDCMIM at the UCB is more reliable than the
micro processor based temperature scanner panel (01) located in the
dusty environment near the Air preheater (10).
Individual thermocouples (06) as shown In fig 2 (b) is short in length
compared to the multi point thermocouple pipe assemblies (02) as
shown in fig 2 (a).
The performance of the device is enhanced as the signal processing
Is done in the DDCMIM (08) at the UCB (09).
The initial cost of the device is reduced.

WE CLAIM:-
1. An improved thermocouple based fire sensing device for regenerative air
preheater comprising:-
- a plurality of individual thermocouple assemblies (06) mounted at
substantially spaced at air outlet and gas outlet paths of the air
preheater (10);
- the thermocouple assemblies (06) sensing the temperature inside
the preheater and generating signals;
- the generated signals are transferred to a digital data control and
monitoring information means (08) via cables (07);
- characterized in that digital data control and monitoring information
means processes the transmitted signals representing the sensed
temperature value and compares the data with respect to a preset
temperature value and generates a fire alarm signal in cases the
data relating to sensed temperature by the thermocouple
assemblies exceeds preset temperature and the fire alarm signal
raises in alarm in unit control board (09).

2. An improved thermocouple based fire sensing device for regenerative air
preheater as substantially described and illustrated herein with reference
to the accompanying drawings.

ABSTRACT

AN IMPROVED THERMOCOUPLE BASED FIRE SENSING
DEVICE FOR REGENERATIVE AIR PREHEATER
The present invention relates to an improved thermocouple based fire sensing
device for regenerative air preheater comprising a plurality of individual
thermocouple assemblies (06) mounted at substantially spaced at air outlet and
gas outlet paths of the air preheater (10) and the thermocouple assemblies (06)
sensing the temperature inside the preheater and generating signals and the
generated signals are transferred to a digital data control and monitoring
information means (08) via cables (07); characterized in that digital data control
and monitoring information means processes the transmitted signals
representing the sensed temperature value and compares the data with respect
to a preset temperature value and generates a fire alarm signal in cases the data
relating to sensed temperature by the thermocouple assemblies exceeds preset
temperature and the fire alarm signal raises in alarm in unit control board (09).

Documents:

00089-kol-2007-correspondence-1.1.pdf

00089-kol-2007-form-18.pdf

0089-kol-2007 abstract.pdf

0089-kol-2007 assignment.pdf

0089-kol-2007 claims.pdf

0089-kol-2007 correspondence others.pdf

0089-kol-2007 description(complete).pdf

0089-kol-2007 drawings.pdf

0089-kol-2007 form-1.pdf

0089-kol-2007 form-2.pdf

0089-kol-2007 form-3.pdf

89-KOL-2007-ABSTRACT.pdf

89-KOL-2007-AMANDED CLAIMS.pdf

89-KOL-2007-CORRESPONDENCE 1.1.pdf

89-KOL-2007-CORRESPONDENCE.pdf

89-KOL-2007-DESCRIPTION (COMPLETE).pdf

89-KOL-2007-DRAWINGS.pdf

89-KOL-2007-EXAMINATION REPORT REPLY RECIEVED.pdf

89-KOL-2007-EXAMINATION REPORT.pdf

89-KOL-2007-FORM 1.pdf

89-KOL-2007-FORM 18.pdf

89-KOL-2007-FORM 2.pdf

89-KOL-2007-FORM 3.pdf

89-KOL-2007-FORM 5.1.pdf

89-KOL-2007-FORM 5.pdf

89-KOL-2007-GPA.pdf

89-KOL-2007-GRANTED-ABSTRACT.pdf

89-KOL-2007-GRANTED-CLAIMS.pdf

89-KOL-2007-GRANTED-DESCRIPTION (COMPLETE).pdf

89-KOL-2007-GRANTED-DRAWINGS.pdf

89-KOL-2007-GRANTED-FORM 1.pdf

89-KOL-2007-GRANTED-FORM 2.pdf

89-KOL-2007-GRANTED-SPECIFICATION.pdf

89-KOL-2007-OTHERS.pdf

89-KOL-2007-PA.pdf

89-KOL-2007-REPLY TO EXAMINATION REPORT.pdf

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Patent Number

253537

Indian Patent Application Number

89/KOL/2007

PG Journal Number

31/2012

Publication Date

03-Aug-2012

Grant Date

30-Jul-2012

Date of Filing

24-Jan-2007

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

Inventors:

#	Inventor's Name	Inventor's Address
1	SHRI PAPPUREDDY PONNUSAMY	BHARAT HEAVY ELECTRICALS LIMITED. RANIPET-632406
2	SHRI DEIVASIGAMANI MANNARMANNAN	BHARAT HEAVY ELECTRICALS LIMITED, RANIPET-632406

PCT International Classification Number

G08B17/06

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA