Furnace Temp

8/2/2019 Furnace Temp

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Furnace Temperature Probe

Weather Proof Construction

Continuous Temperature Readings

Air Cooled Furnace Temperature Probe

Indication or Recording

For Automated Station

Principle of Operation

Four-Button Station

Three-Button Station

Furna

ce

Tem

peratur

eProbe


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Contd...

Helps speedy boiler start-up with constant check on gas

temperatures in critical furnace or superheater/re-heater passes.

Here is a positive aid to faster start-up of steam

generators. It is a dependable means of determining

furnace temperatures from the moment of lighting off

until the unit is ready to go up to load. Gas

temperatures can therefore be more easily held within

safe limits. This is an added protection for costly

boiler equipment during the periods when such

equipment is most subject to hazard.


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Weather-proof Construction


Contd...

The BHEL Probe is weather-proof. It can be used indoors oroutdoors. All working parts are corrosion-resistant, and are

protected by a combined heavy gauge steel housing and frame.

Design of the Probe is based on that of the Model LRD IE long

retractable soot blower. This rugged unit has repeatedly proven

its reliability in operation for numerous modern, heavy-duty,

utility and industrial boilers. In the probe, the lance

does not rotate. It simply traverses back and forth

across the furnace or superheater pass, driven by a single

electric motor. The chain drive is enclosed in the housing to

reduce maintenance and to increase safety of operation.


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The Furnace Temperature Probe travels back and forth - automatically, or

under push-button control - through the critical passes of the furnace orsuperheater.

As the Probe travels and senses the temperature, additional facility can be

included to show the extent of probe travel inside the furnace. This gives

the operator a continuous check on any potential 'hot spots' that might

develop during the lighting-off period. This continuous check in the furnace

temperature is an invaluable guide to correct firing procedures.

Gas temperatures are measured by a thermocouple mounted on the end

of the lance. Extension wires are enclosed in the housing for protection.

The standard equipment is suitable for temperatures up to 538C and is

without air cooling arrangement.

When it is necessary to measure higher temperature upto 815C, it ispossible with air cooled units as described on the next page.

Continuous Temperature Readings


Contd...


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As seen from the top, the position transmitter (1) is coupled to the drive

mechanism and protected within the steel housing. The single chain drive is also

enclosed. Cooling air when specified is admitted through the opening at the front

of the power track housing through a piston operated ball valve (2). Air supply is

automatically controlled by probe position.

Should power fail, the lance can be retracted by a crank which engages with the

spring loaded coupling shown near the inboard end of the housing.

The side view shows how the self-cleaning, low friction, corrosion resistant chaindrive is housed for protection and supported by a track within the housing. The

chain needs no lubrication. It is easy to inspect and maintain. The chain is pre-

stressed to minimize possibility of stretching while in service. Adjustment, if

required, is external and may be made while the Probe is operating.



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REFERENCES INDEXSTART CONTACT US EXIT

The Power track (3) is attached to the travelling carriage on one end

and is stationary at the cooling air valve inlet (2). As the travellingcarriage is extended into the furnace the power track carries the

thermocouple extension wire (4) and air supply hose (5), when air

cooling is required.

NOTEl The power track does not slide on the support structure but is merely lifted up as the

travelling carriage is extended into the furnace.

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Out board end showing position

transmitter, power track supportingcooling air hose and thermocoupleextension wire with connection to theback of the travelling carriage.

For lance extensions below 16 feet and gas temperature

of 649C or lower there is no need for cooling the lance.

Automatic retraction from the recorder alarm protects the

lance at excessive temperatures.

When air cooling is envisaged, the lance is supplied with

an inner lining for optimum utilization of the cooling air.

The cooling air is introduced into the travelling carriage. It

passes through a small annular space between the lance

wall and the inner liner. It then is discharged from a nozzle

into the furnace.

This nozzle is mounted back from the end of the lance. It

is slanted away from the thermocouple, so that discharged

air will have no effect on the temperature readings.



Contd...


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Terminal-strip junction box and push-buttonstation, factory wired and mounted, simplifyfield wiring. Either may be at any convenientlocation along housing. Motor starters may alsobe mounted on Probe eliminating junction box.

Indication or Recording

Temperatures sensed by the Probe may be indicated or

recorded in several ways, depending on needs ordesires of the individual user.

Temperatures only, or temperatures and Probe position,

may be registered.

Temperatures only may be registered on a standard

temperature recorder.

Temperature and Probe position may both be registered

on a two-pen recorder. A two-pen recorder gives an

instantaneous picture of conditions within the furnace,

and shows exactly where they exist. It should be

supplemented by a high-temperature alarm and, if

desired, by a thermocouple-failure alarm.


Contd...


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Boiler end : Thermocouple iscompletely protected by stainlesssteel/INCONEL sheath. Easily replacedthrough the heat-resisting compression-type fitting. Hardened hourglass lowerroller supports overhanging load as lanceextends. Upper roller prevents lance play


Contd...

Probe position is transmitted by a 3600-degree

(10-revolution) potentiometer, gear train and remote

reading indicator. This is standard equipment.

BHEL does not manufacture indicators or recorders,

but can furnish any make or type specified. The user

may, if he prefers, purchase such instruments

separately from instrument manufacturers.

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For Automated Station

Principle of Operation

Circuitry of the BHEL START UP Probe may be arranged for use withthe most modern scanning, automatic start up, and computer

systems.

The Probe normally moves back and forth across the furnace at

approximately 3 meters per minute.

With standard equipment, the lag between Probe position

and corresponding thermocouple temperature is about

35 seconds. If a multiple-point recorder is used, the lag increases

slightly, depending on the number of print positions incorporated.


Contd...

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If temperatures registered by the Probe are no more than 649 C.,

they are normally within 5C of readings taken from test

thermocouples mounted in the furnace pass traversed. At higher

temperatures, the thermocouple reading may be affected by

furnace radiation.

However, the Probe is normally used to indicate superheater tube

temperatures. The thermocouple is therefore placed to react to the

exact furnace conditions affecting the tubes.

The single driving motor is controlled by push buttons conveniently

mounted on the side of the Probe. A parallel push-button station is

normally mounted on the boiler control panel. The four-button

station illustrated offers several operating options.

The lance-mounted thermocouple may be set in motion to continue

repeated automatic traversing back and forth across the furnace or

superheater. (By pressing the 'START' push button.)

Four-Button Station

EXTENDRetractStopPark

Extend

StopPark

RETRACT

ExtendRetract

ParkSTOP

ExtendRetractStopPARK



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The thermocouple may be stopped at any point along its path to give a continuing

report on the temperatures at this point.

The lance may be caused to retract instantly from either a stop position or any

point reached while it is extending.

The thermocouple may be placed in the 'Park' - or fully-retracted - position to rest

outside the furnace, away from the high temperature gases.

The furnace Probe may also be equipped with a three-button station offering

several options.

The lance may be caused to extend to any fixed point, then come to a stop.

The lance may be stopped at any position, as with the four-button station.

The lance may be caused to start retracting at any time and from any position.

NOTE

The materials and dimensions specified are indicative and are subject to change without prior intimation inview of the constant design improvements being incorporated.

Three-Button Station

Furnace Temp

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