Furnaces bases operation

Август 22, 2022

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Furnaces bases operation

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2. Furnaces of the past, aero-fuel or gas melting, very high consumption
3. Port End furnace standard in verallia significant reduction in consumption by regeneration (T ° of combustion
4. Electric furnaces, very limited surface and pull
5. Port End furnace standard in verallia Front wall Ports necks Regenerators
6. Theoretical consumption Formula of a furnace: Main parameters of the furnace design: Thermal losses of the
7. Theoretical consumption Formula of a furnace: Main parameters of the furnace design: Regenerators: >> impacts directly
8. Theoretical consumption Formula of a furnace: Given by the Furnace design: Consump.= k x [ A
9. The operation parameter necessary for a good steering: With pull or cullet% or boosting Power changes.
10. In the production of flint or extra flint glass (low concentration of iron oxide Fe2O3), the
11. Dark Reduced Glass (High concentration of Fe2O3 and FeO): In the production of colored glass the
12. In the case of Flint Glass. After 2,9T/m2, the additional tons are melted by the boosting.
13. Theoritical Consumption equation of a furnace: in Flint Glass. BTS Oil PCI = 9700 Kcal/Kg Theoretical
14. Theoritical Consumption equation of a furnace: in flint. (It depends of the % of cullet) Same
15. In the case of Dark Glass: We need the boosting earlier at lower pull. In certain
16. Theoritical Consumption equation of a furnace: in Dark Glass. We need the boosting earlier, at lower
17. Optical Furnace superstructure Temperature control: Crowns silica Backup Fast Control of the crowns temperatures profil above
18. Optical Furnace superstructure Temperature control: Crowns silica Backup Fast Control of the crowns temperatures profil above
19. Furnace maximum admissible temperatures for each furnace area : 1510°C Regenerator Port entrance Wall/Arch 1615°C Optical
20. Exemple of batch piles distribution: OK NOT OK = Seeds risks Dogs houses : batch piles
21. The operation parameters necessary for a good steering: At stable pull. Which Furnace Steering Setpoints and
22. The operation parameters necessary for a good steering: At stable pull. Which Furnace Steering Setpoints and
23. The operation parameters necessary for a good steering: At stable pull. Which Furnace Steering Setpoints and
24. At the end of the campaign, we see perfectly the corrosion striations of convection along the
25. Furnace Operation & Steering: The HOT POINT POSITION and the TANK CONVECTION:
26. D. Grand MP & EV 2012 Furnace Operation & Steering: The HOT POINT POSITION and the
27. Which Maintenance? 1 – Check once a year under the furnace with ampermeters and voltmeter that
28. Power management of boosting groups: if we spend a lot of power on 1 single group
29. Essen F1 2020 (Sorg electrodes) : Current situation on the G melting electrode blocks N °
30. corrosion Original remaining corrosion Zone framed in yellow: zone with the most drilling surveys greater than
31. Thermocouple installed 10mm in 2nd layer of fire clay and every m² Cooling holes : Drill
32. Bottom cooling system: Zorya F2 bottom cooling system, the best system is this one because it
33. Bottom cooling System : Zorya F2 collectors
34. Essen F1 volution Electrodes T° / Pushing : the first conclusion that we can make: the
35. Incidents: AZS leack If the power is not stopped immediatly, the electrode block temperature increase until
36. Incidents: metal particles in foreign cullet and accumulation on the bottom of the furnace Diminution of
37. Bubblers: Management of bubblers / Risk When FLAME transfert to the bottom is saturated. Superstructure temperature
38. The ceramic bubbler: Alumina Bubbler block completly worn. 7 cm remaining thickness after the furnace stop
39. The operation parameters necessary for a good steering: At stable pull. Which Furnace Steering Setpoints and
40. The operation parameters necessary for a good steering: At stable pull. Which Furnace Steering Setpoints and
41. Regenerator Checker Maintenance: 1 – Never leave the thickness of sulfates deposites increase under the rider
42. 5 – Control moisture and plasticity of the batch . Pay attention to the fines raw
43. Restrictions of checkers section induce dramatic diminution of combustion yield, end the furnace consumption increases. Regenerator
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Furnaces of the past, aero-fuel or gas melting, very high consumption

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Port End furnace standard in verallia significant reduction in consumption by

regeneration (T ° of combustion air 1400/1450 °)

Oxygen (oxy-gas), generally used for small production capacities (high cost of oxygen)

Current furnaces

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Electric furnaces,
very limited
surface and
pull

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Port End furnace standard in verallia
Front wall
Ports necks
Regenerators

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Theoretical consumption Formula of a furnace: Main parameters of the furnace

design:
Thermal losses of the furnace depend on the:
Insulation of the furnace: Bottom / Tank / Crowns / Breastwalls
Insulation removal due to the weak points maintenance
Exchange Surface of the superstructure and the tank
Cooling of the glass tank level (Mandatory!!)
Cooling of all water jacket like electrode holders, throat ceiling block cooling, batch charger cooling.

All these design parameters have a direct impact on the A, B, C, D coeffcients.

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Theoretical consumption Formula of a furnace: Main parameters of the furnace

design:
Regenerators: >> impacts directly the Combustion efficiency.
Number of regenerators: single / double or triple passes
Height and section of the regenerator(s)
Kind and density of checkers piling. ( chimney blocs, cruciforms, their shape,…)
Insulation of the regenerator walls.
The Glass Temperature at the Working End entrance:
High Temperature >> Higher consumption.
Heating Value of the Gas or the Heavy Oil:
Kwh/ Nm3 or Kwh/ Kg

All these design parameters have a direct impact on the A, B, C, D coeffcients.

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Theoretical consumption Formula of a furnace: Given by the Furnace design:
Consump.=

k x [ A + B x Pull x (1-C x Cullet%) – W / D
Consumption: Ton of oil / day or Nm3 gas / day
Pull: T/day
0< Cullet % <1.
W is the Boosting energy used by day: Kwh/24h
A, B, C, D are 4 coefficients linked with a particular Furnace Design. If the furnace design changes, the coefficients change.
So this formula is valide only for one particular funace
K is the coefficient of aging: k = [1 + 0,0125 x n] where « n » is the number of years of campaign since the furnace startup.

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The operation parameter necessary for a good steering: With pull or

cullet% or boosting Power changes.
IS Machines Production changes management:
It is necessary to plan precise pull changes and the production must respect the hour of changes, otherwise it’s not possible to control the furnace energy and temperatures.
Change time and pull variation clearly defined for each IS machine.
Purge a forehearth with uncontroled pull to recover fast the setpoint temperatures at the last moment is a current practice to be prohibited. No possible control of the furnace pull, no time to react in real time, loss of furnace temperatures, delay to be compensated, and final T variations in the working end.
Put clear instructions to ajust the furnace total power and the time of each machines pull changes.
Use the excel sheet software to do the power calculation.
The Excel file is setup with particular Coefficients relative to one single furnace .
It takes in consideration the furnace aging (date of startup), the pull , the electrical power and total cullet % variations.

Furnace Operation & Steering:

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In the production of flint or extra flint glass (low concentration

of iron oxide Fe2O3), the transmission of energy in the glass (infrared spectrum) is sufficient to transmit the energy to the bottom (1.5m).
Up to 2.9 t / m² of pull, the T ° of the crowns is gradually adjusted (only by fossil fuels) between 1550 and 1620 °.
As soon as the pull reaches 2.9t (coverage of the glass surface overcrowding), the boosting will be started and gradually adjusted according to the bottom T°.
Bottom T° beyond 1300 ° (through equivalent) are excessive and unnecessary (energy cost, premature corrosion of infrastructures, the relationship between T ° of glass and corrosion of refractory is expotential)
Economical control: daily energy saving work is necessary (excluding pull change time), maintaining the T ° to have sufficient quality (quality specifications), i.e. just above the threshold for the appearance of melting defects (low consumption and low corrosion of the furnace). From 2.9 t / m² the energy adjustment is carried out by boosting (for this pull you must absolutely melt the raw materials correctly, silica inclusions)

Flint Glass

Furnace Operation & Steering:

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Dark Reduced Glass (High concentration of Fe2O3 and FeO):
In the production

of colored glass the transmission of energy by the flames is very reduced (maximum 300mm of depth), to activate the convection it will be necessary to add electric boosting, (a furnace which has a low convection will produce a glass with a lot of of nephelinization inclusion defects, seeds).
The raw materials are melted by the flames (maximum T ° beyond pull sup or equal to 2.1 t / m²), then we will adjust the electric boosting to have a correct convection (the T ° of bottom dog houses, middle before dam and WE raiser)
Bottom T° beyond 1300 ° (through equivalent) are excessive and unnecessary (energy cost, premature corrosion of infrastructures, the relationship between T ° of glass and corrosion of refractory is expotential
Economical control: daily energy saving work is necessary (excluding pull change time), maintaining the T ° to have sufficient quality (quality specifications), i.e. just above the threshold for the appearance of melting defects (low consumption and low corrosion of the furnace). The energy adjustment is carried out by boosting, from 2.1 t / m² the T ° of the crowns are stabilized between 1610/20 ° (you must absolutely melt the raw materials correctly, silica inclusions)

Dark Glass

Furnace Operation & Steering:

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In the case of Flint Glass. After 2,9T/m2, the additional tons

are melted by the boosting.

Furnace Operation & Steering:

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Theoritical Consumption equation of a furnace: in Flint Glass.
BTS Oil
PCI =

9700 Kcal/Kg

Theoretical Consumption Equation at begining of the campaign

C= Is the daily oil consumption Kg/24h
T = furnace daily Pull
C’ = Percentage of cullet
W = Electrical energie for Kwh/24h

C = Kg BTS Oil / 24h

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Theoritical Consumption equation of a furnace: in flint. (It depends of

the % of cullet)
Same conditions but with 100% of cullet instead of 15%

C = Kg BTS Oil / 24h

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In the case of Dark Glass: We need the boosting earlier

at lower pull. In certain cases, for very dark glasses, a minimal amount of boosting is used immediatly, at very low pulls.

Furnace Operation & Steering:

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Theoritical Consumption equation of a furnace: in Dark Glass. We need

the boosting earlier, at lower pull. Near 2,2 – 2,5 T/d/m2 the need of boosting increases. This electrical power curve depends a lot on the color and local practice of the Melting team.

BTS Oil

PCI = 9700 Kcal/Kg

Theoretical Consumption Equation at begining of the campaign

C= Is the daily oil consumption Kg/24h
T = furnace daily Pull
C’ = Percentage of cullet
W = Electrical energie for Kwh/24h

C = Kg BTS Oil / 24h

A, B, C, D coefficients are quite the same in Flint or Dark Glass

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Optical Furnace superstructure Temperature control: Crowns silica Backup
Fast Control of the

crowns temperatures profil above the flames:
(confortable and fast in case of doubt)
From the opposite breastwalls peephole in front of the flames.
2 minutes before the end of flame time.
Target the crown silica above the flame on Ring 1, Ring 2 and Ring 3 if there is one.
Remove 20°C from the measurements (to consider the flame presence ).
It’s a fast control, that allows in two reversal times (L/R) to have a quite clear vision of the flame power distribution inside the furnace laboratory and to check also the crowns thermocouples condition.
Very convenient in case of defecting or missing crown thermocouples or bad thermocouples tip position (too inside or too outside, compared to the crowns inner surface).

Furnace Operation & Steering:

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Optical Furnace superstructure Temperature control: Crowns silica Backup
Fast Control of the

crowns temperatures profil above the flames:
(confortable and fast in case of doubt)

Controlling thermocouples T° with optical pyrometer:

From the opposite breastwalls peephole in front of the flames.
2 minutes before the end of flame time.
Target the crown silica above the flame on Ring 1, Ring 2 and Ring 3 if there is one.
Compare the T ° taken with the optical pyrometer with the T ° of the thermocouples, adapt the combustion (injector settings) to have a curve close to the theory

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Furnace maximum admissible temperatures for each furnace area :
1510°C Regenerator Port

entrance Wall/Arch

1615°C Optical AZS Breastwalls at flame Stop

1620°C Crowns Alarm reduce fossile flow
1625°C Stop fossile flow
For Verallia Furnace Standard Thermcouple positions

1610°C FrontWall

1360°C
Throat Exit
Thermocouple 90mm inside the glass

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Exemple of batch piles distribution:
OK
NOT OK = Seeds risks
Dogs houses :

batch piles distribution

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The operation parameters necessary for a good steering: At stable pull.
Which

Furnace Steering Setpoints and Why:
On the superstructure:
Combustion parameters: (contrôle des NOx).
Specific thrust Mini – Maxi. (Adaptation of injection diameters)
Inclination / Azimut.
Condition of injectors: Cleanliness and status.
Fumes analyze at the port neck sides (CO 5000ppm maxi, NOx)
Fumes analyzes at the stach, with reaction standard procedure in case of deviation on CO or NOx
Flame shape and development looking at the front wall endoscope screen.

Furnace Operation & Steering:

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The operation parameters necessary for a good steering: At stable pull.
Which

Furnace Steering Setpoints and Why:
On the infrastructure: Tank bottom (Electrical power steering).
Define a pilot thermocouple as the reference temperature (with a setpoint) to drive the boosting: Ideally melting bottom thermocouple in front of the doghouses, distante from the electrodes blocks.
The Electrical Power steering is operated following the evolution of the impedance of an electrode group that changes when the average glass temperature evolves. (fine tuning).
When the glass tank temperature decreases (the bottom temperature will decrease very soon), the conductivity of the glass decreases, so the impedance of the glass increases, so you must inject more tension to increase the power, and increase the glass temperature.
+1°C bottom temperature ⬄ -0,3 mOhm impedance.
-1°C bottom temperature ⬄ +0,3 mOhm impedance.
It is the finest and fastest way to anticipate any bottom temperature drift!!
Define the step of maximale power variation (KW), and minimum delay before adjusting the power setpoint another time.

Electric Boosting :

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The operation parameters necessary for a good steering: At stable pull.
Which

Furnace Steering Setpoints and Why:
On the infrastructure: Electrical power steering and distribution.
Power management of boosting groups: if we spend a lot of power on 1 single group and not on another, the risk is that the electrode blocks of the most used group will be corroded before the end of the campaign, this has been and is the case on several furnaces in Italy, which will generate significant risks of reduction of pull (following the shutdown of an electrical group) and of glass leakage if preventive and conservative measures are not taken correctly moment. During the campaign, calculate the cumulative GW on each group, make an assessment each year and modify the powers on each group to arrive at the end of the campaign with an equivalent corrosion of the blocks of electrodes on each group
Define and manage the power distribution between the electrode groups G3/G2/G1, and identify which electrode group power will be adjusted to stabilize the impedance.
In flint glass, put max of power on G3 near the barrage and complete with G2. If G2 is at the maximum, start using G1.
In Dark glass, try to balance the power on each group equally.
Define on which electrode group you steer the boosting power to adjust the impedance and the bottom temperature.
It depends on the power reserve of each group.

Electric Boosting :

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At the end of the campaign, we see perfectly the corrosion

striations of convection along the tank vertical soldier blocks:

D. Grand MP & EV 2012

Furnace Operation & Steering:

The HOT POINT POSITION and the TANK CONVECTION:

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<< Throat
Furnace Operation & Steering:
The HOT POINT POSITION and the TANK

CONVECTION:

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D. Grand MP & EV 2012
Furnace Operation & Steering:
The HOT POINT

POSITION and the TANK CONVECTION:

Glass Tank Convection Study By Mathematical Modelisation Movi

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Which Maintenance?
1 – Check once a year under the furnace

with ampermeters and voltmeter that supervision indications are correct on the display and that the power calculation is correct. P(Kw)= 1,732 U average/phase (V) x I average/phase (A).
2 - Check each electrode group impedance once a year. Compare the result with the theoreticol values: mOhm. If the impedance increases, the exchange surface of the electrodes decreases, you must push to compensate.
3 – Other possibility, put 100V and compare the intensity with the last statements.
4 - Pratically push the Verallia electrodes twice a year 15 mm in dark glass with foreign cullet. It unstick the electrodes from the surrouding metals and move up the lower part of the molybdenum where the metal wear the Molybdenum avoiding dramatic electrode breakage..
5 – Always note mm lenght you pushed and the date for each electrode since the furnace startup.

- Electrodes boosting :

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Power management of boosting groups: if we spend a lot of

power on 1 single group and not on another, the risk is that the electrode blocks of the most used group will be corroded before the end of the campaign, this has been and is the case on several furnaces in Italy, which will generate significant risks of reduction of pull (following the shutdown of an electrical group) and of glass leakage if preventive and conservative measures are not taken correctly moment. During the campaign, calculate the cumulative GW on each group, make an assessment each year and modify the powers on each group to arrive at the end of the campaign with an equivalent corrosion of the blocks of electrodes on each group

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Essen F1 2020 (Sorg electrodes) : Current situation on the G

melting electrode blocks N ° 8 and N ° 9:
N ° 9, the T ° holder has been increasing for several years, the holder has been replaced several times without success (T ° with boosting = 750 °), the holder showing no anomaly (water leak, normal circulation of the water), which means that the AZS block is corroded, recently a small glass infiltration appeared, the electrode was disconnected.
N ° 8, similar situation, the holder was replaced 2 years ago, the T ° also increases abnormally, we also notice an abnormal inclination 2.7 °, the electrode is also disconnected and sprayed with a water lance.

N°8

N°9

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corrosion
Original
remaining
corrosion
Zone framed in yellow: zone with the most drilling surveys greater

than 70% corrosion,
I consider that the entire framed area must be ventilated before any repair (AZS chips or HBR)

Essen F1, controlling the bottom thickness around the electrodes blocks : drilling surveys carried out recently

%
corrosion

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Thermocouple installed
10mm in 2nd layer of
fire clay and every

m²

Cooling holes :
Drill 120mm in
3 layers of insulation
Every 300/400mm

Essen F1, cooling the most corroded part of the bottom
installation of thermocouples to control and monitor the T ° of the most corroded bottom

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Bottom cooling system: Zorya F2 bottom cooling system,
the best system is

this one because it reduces the lengths of the flexibles and therefore less pressure drops

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Bottom cooling
System :
Zorya F2 collectors

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Essen F1 volution Electrodes T° / Pushing : the first conclusion

that we can make: the pushings were insufficient and carried out too late: I think that the pushings should be carried out when the evolution of T ° is between 50 and 80 °

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Incidents: AZS leack
If the power is not stopped immediatly, the

electrode block temperature increase until the AZS melting and leackage. And after the glass will arrive soon.
Exemple of AZS and glass leackage. Water jacket and additional water lances allowed to stop the glass leack.

bottom glass infiltrated leak, loaded with metals (Pb, Zn, Sn, Cu, Fe, red)

Melted AZS leak before glass leakage

- Electric Boosting : verallia type électrodes

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Incidents: metal particles in foreign cullet and accumulation on the bottom

of the furnace
Diminution of the lower molybdenum bar section without fatal break

- Boosting Power:

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Bubblers:
Management of bubblers / Risk
When
FLAME transfert to the bottom is

saturated.
Superstructure temperature are too high, bottom temperature is too low.
No bottom electrodes.
Bubbler action:
Dope the furnace by other means than conventional flame or boosting.
Flow 1 - 10 l/mn max, 25 – 30 bubble /min on the surface maximum.
Near the barrage.
Positive aspects:
Move the glass from the bottom to the surface, perfect for dark reduced glasses.
Improve drastically the FLAME ⇒ GLASS transfert decreasing the glass bath surface temperature
Drastic diminution of the boosting consumption, and melting cost.
Intense convection in the tank, good for glass homogeneity.
Negative aspects:
It Creates fine bubbles especially at high flow and high pull rate. It degrades partially the glass quality.
It oxidizes the reduced glasses and move partially the color.
It induces a deep and fast corrosion of the bottom AZS plates upstream the bubblers line and a strong wear of the bubblers blocks if bubblers are not pushed regularly.

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The ceramic bubbler: Alumina
Bubbler block completly worn. 7 cm remaining thickness

after the furnace stop at the end of the campaign,
You need to push the bubbler twice a year 50 + 50mm to compensate the bubbling alumina corrosion

Bubblers:

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The operation parameters necessary for a good steering: At stable pull.
Which

Furnace Steering Setpoints and Why:
On the superstructure:
Furnace Pressure: By automatic regulation, target 5 Pa. Look at the peep holes on the opposite side of the flame: flame must be 1/3 inside and 2/3 outside the peep hole, it’s a good indicator to check fast the situation.
Too Low pressure >> Cold air entrances increase, energy consumption increase.
Too High Pressure >> furnace and regenerators silica superstrucutre degradation, flames coming out corroding the silica crowns and the walls. Beyond + 10Pa without being able to go down again, it is absolutely necessary to reduce the pull in order to reduce the energy and consequently the pressure which must be less than 10Pa
Check the upper tank walls joint (hermetic), to limit air ventilation leaks inside the furnace, that impacts the furnace pressure in case of bad situation on the checkers and increase the energy consumption.
Check once by month the fumes pressure along the fumes circuit from the checker base until the stack. To identify the pluggings or the atmosferic air entrances positions. Operate targeted cleanings and sealings, in order to keep the furnace pressure in a correct range of value.

Furnace Operation & Steering:

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The operation parameters necessary for a good steering: At stable pull.
Which

Furnace Steering Setpoints and Why:
Upper and lower regenerators and fumes circuit Températures:
Enable to verify if the combustion proceeds normally , and that the flames do not lengthen, that the combustion inside the furnace is stable and the heat transfert flow to the batch compostion doesn’t change. It’s a good reference point of the end of combustion area (at constant power) and it is a good complement to O2 and CO fumes analysis at the port neck : The target is not to burn inside the checker’s packs in the regenerators, but to end the combustion inside the furnace.
Measure of the temperature by pyrometer on the port entrance arch key at the end of the flame time. Allow the compare the temperature with the crown thermocouple indication and a max temperature (1510°). It’s a safe precaution for silica superstructures and AZS cruciform checkers that don’t appreciate excess of CO inside the regenerators aswell as excessive temperatures.

Furnace Operation & Steering:

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Regenerator Checker Maintenance:
1 – Never leave the thickness of sulfates deposites

increase under the rider arches more than the half height between the bootom and the rider arches key. It favours preferential passages inside the checkers packs, accelerate the local corrosion and wear with risks of premature collapses, create pluggings in other cold areas.
2 – Proceed with yearly thermal cleanings, dice the 4th year of campaign to eliminate dark areas on the light pattern under the checker.
3 – Prefer local thermal cleaning with localized air/gas lances. Prohibite global thermal cleaning with big burners that lead sometime to dramatic collapses of the rider arches.

Best Practice Sheet: Regenerator’s maintenance

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5 – Control moisture and plasticity of the batch . Pay

attention to the fines raw material particules that stick to the regenerator’s chechers, corrode and plug them. Moisture 3,5%, batch temperature > 37°,
6 – Never exceed 5000ppm CO at the prot neck. To reduced combustion favour corrosion of cruciform 1682RX.
7 – Never proceed disbalancing the flame time to clean the checkers. It increase all the volume of the checker and increase overall the preferential passages. Risk of un-crontrolled collapse.
8 – Long periodes with very low pull and cold regenerator favours the condensation inside the checkers packs. Plan a checker yearly cleaning.
9 – Changes of combustible from gas to oil and vice versa modify the thermal field inside the checkers and favour the condensations especially in gas firing condition.

Regenerator Checker maintenance:

Best Practice Sheet: Regenerator’s maintenance

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