Glass Industry
Recuperative Continuous Furnace with Gathering
design&construction in the glass world
Recuperative
Continuous
Furnace with
Gathering
bays up to 30
Ton/Day for
semi-automatic
production
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Unit melter recuperative glass furnace is the most used furnace for production
between 5 and 30 ton/day.
It is used for semi-automatic production with gathering Robots of:
Tableware, Parfumery bottles, Head lamps for car, Glass electric isolators, Glass for
lighting.
This kind of furnace can be assembled with gathering bays for forehearth channel.
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Falorni Gianfranco s.r.l.
www.falorniglass.com
Glass Industry
Recuperative Continuous Furnace with Gathering
design&construction in the glass world
Description
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ADVANTAGES OF THE U-MELTER SYSTEM IN FURNACES
OF SMALL-MEDIUM DIMENSIONS
Until the sixties, all furnaces had END PORT burners because the only fuel used for
melting was heavy fuel. This fuel, in comparison with the methane gas, burns more slowly
and thus produces a much longer flame.
This is the reason why in the past the burners were placed in the end side of the furnace
and never across it.
With the arrival of natural gas in the factories, designers initially tried to change only the
burners, leaving unchanged the design of the furnaces.
In about 15 years however, designers have almost completely abandoned the solution of
the END PORT burners, in favour of the so-called cross fire U-melter system.
The only exceptions to this practice are represented by very small furnaces (for
reasons of easiness and cost) and those exceeding 40-50 tons, which use huge
and expensive regenerators and recuperators of refractory metal to heat the
combustion air.
The reasons why the cross-burning furnaces have better performance and better
consumptions are the following:
• Larger surface area of heat exchange between the flame and molten glass
• Creation of currents in the glass, which promote fusion and refining. The sketch here
below, explains the first reason.
We can see how the flames of two burners (on the left, Figure 1) cover less area
than ​​four burners (on the right, Figure 2).
Besides, in the first case the flames exchange the heating with the raw material (Figure
1) that enters in the furnace, while in the U-melter system the heat exchange occurs
between the flame and the molten glass (Figure 2).
The exchange of heat between the cold composition and the hot flame is much
less than the one which occurs between the hot glass and the flame. In fact, the
molten glass is a good conductor of heat, while the composition behaves as an insulator
and acts as a screen between the flame and the liquid glass.
We can say that, having the same surface of the melting tank and the same quantity
of raw material charged, the U-melter furnace (Figure 2) on the right can work at a
temperature of 20-30 degrees lower.
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Falorni Gianfranco s.r.l.
www.falorniglass.com
Glass Industry
Recuperative Continuous Furnace with Gathering
design&construction in the glass world
Description
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The side burners create a hottest zone in the furnace, called refining area.
Melter Furnace
In this area the glass heats up and tends to rise to the surface, where it reaches its
maximum temperature. The heating and the upward movement, cause the refining of the
melted glass, that is to say to lose the gas bubbles created by the dissociations of the
components of the mixture.
Another positive effect on the furnace functioning is given by the current of hot glass that
heats the mixture that has just entered the tank, and thus promotes its melting.
Data Sheet
Number of sidewall burners: From 4 to 10 burners
Melting capacity Range:
From 5 to 30 tons / 24 hours
Melting area range: From 6 to 20 m²
Glass type and color:
High quality soda-lime flint and colored glass
Melting temperature:
1550°C
Length/width ratio:
2,1/1
Specific melting rate:
From 0,8 to 1,5. ton/ m²
Number and type of batch chargers:
One oscillating pusher type charger
Type of energy:
Natural gas
Preheating of combustion air:
Double shell steel recuperator till 600°C
Tubes bundle recuperator till 750°C (only for 20 ton/day furnace)
Energy consumption:
30 ton per day furnace with 600°C hot air, energy consumption 2100 kcal/kg of glass
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Falorni Gianfranco s.r.l.
www.falorniglass.com
Glass Industry
Recuperative Continuous Furnace with Gathering
design&construction in the glass world
Heat
Recuperator
‘Tube bundle’
Data Sheet
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The standard design consists in a cylindrical tube bundle, made with tubes 253MA
steel, which is installed in a vertical shaft insulated with refractory material. This
shaft is located directly on the furnace chimney.
This recuperator produces a max. air preheat of 800°C and it can receive waste gas
at 1600°C.
The tube bundle heat exchanger is composed by tubes mounted on a double shell
with cylindrical shape, made of an inside cylinder in refractory 253 MA thickness 5
mm.
The tube bundle recuperator can be combined with a second recuperator double
shell type, in order to improve the heat exhange.
ENERGY SAVING
• The energy saving of such recuperator is very high, we normally calculate
that every 100°C of temperature of the combustion air, corresponds to 5%
of energy saving. It means that with a heat recovery system ‘tube Bundle‘
recuperator the energy saving is between 40 -45%.
STACK BASE VALVE
At the stack base of the chimney a security valve will be installed. This valve is necessary
to avoid the overheating of the recuperator in case of lack of electric energy or stop of
the air fan (this event is very dangerous for the refractory steel inside of the recuperator).
In this event, the valve opens automatically and cold air goes inside, keeping the steel
temperature below the dangerous level.
A thermocouple K type is mounted in the outlet air pipe and it is connected with
a digital regulator where the operator sets the working temperature. In case of
overheating of the combustion air, the digital controller drives the opening of
the security valve (see the sketch below).
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Falorni Gianfranco s.r.l.
www.falorniglass.com
Glass Industry
Recuperative Continuous Furnace with Gathering
design&construction in the glass world
Heat
Recuperator
‘Double shell’
Up to 600°C
Data Sheet
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This type of recuperator consists in two cylinders of similar diameter made with heat
resistant steel and insulated outside with ceramic fiber and rock-wool. The heat
exchanging area is the anular space formed between the two concentric cylinders:
in fact the hot waste gas passes through the inner tube, heating the steel till 800°C,
and the combustion air passes through the anular space cooling the steel and
heating up itself till 600°C.
The stainless steel inside of the recuperator is avalaiable in two qualities: AISI 310S
and 253MA.
The double shell recuperator can be used in single modules or in double modules
with two recuperators one after the other.
This kind of recuperator is used for furnaces of small dimensions up to 50 ton / day.
The double shell recuperator has a overheating safety system installed on the
refractory material of the chimney. This system consists in a stack base motorized
valve, that through a cold air flow, regulates the temperature of the waste gas in
the chimney in case of overheating, and cooling the recuperator in case of stop of
combustion air flow (due to black out or electroventilator breakage ).
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www.falorniglass.com
Glass Industry
Recuperative Continuous Furnace with Gathering
design&construction in the glass world
Hot Air Control
Stack Base
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Furnace
Construction
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The Double shell recuperator has a overheating safety system installed on
the refractory material part of the chimney. This system consists in a stack base
motorized valve, that through a cold air flow, regulates the temperature of the waste
gas in the chimney in case of overheating and cooling, the recuperator in case of
stop of combustion air flow (due to black out or electroventilator breakage).
This system allows to have a longer life of the recuperator and avoids any possible
overheating of the refractory steel.
The system consists in one motorized butterfly valve installed on the basis of the
chimney. This valve is connected to a thermocouple on the hot air piping, through a
digital controller (see the sketch).
The controller receives the temperature signal from the thermocouple and manages
the set temperature of the hot air, opening and closing the cold air flow.
The servomotor is armed with a strong spring that in case of lack of
electric energy opens completely the butterfly valve.
The demolition and reconstruction of the furnace are the most demanding
operations in the realization of the plant.
FALORNI company has e very specialized end experienced technical staff, able to
deliver the furnace completely assembled and started into production, including the
pre-heating of the whole plant.
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Falorni Gianfranco s.r.l.
www.falorniglass.com
Glass Industry
Recuperative Continuous Furnace with Gathering
design&construction in the glass world
[email protected]
Recuperative
Continuous
Furnace with
Gathering
bays Lay-Out
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Falorni Gianfranco s.r.l.
www.falorniglass.com
Glass Industry
Recuperative Continuous Furnace with Gathering
design&construction in the glass world
Combustion
Systems
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The combustion units are pre-assembled into a steel frame unit, delivered fully
piped, wired and tested
Each gas line in the Natural gas combustion ramp is composed by:
• Gas Filtration
• Flexible joint
• Gas Pressure regulation
• Shut off valves
• Safety valves
• Gas Flow measure transmitter
• Air Flow measure transmitter
• Motorized gas valve for control
• Manual by pass electric valve set
• Air Fans controlled by inverter
Air Regulation
The air Digital controller drives the electronic inverter and it makes vary the fan
motor’s turns. An electronic device, through a calibrate orifice, measures the quantity of
air and sends the input to the electronic gas flow controller.
Gas Regulation
The gas flow controller makes the matematic ratio based on the air quantity, and control
the gas flow through a motorized valve.
On the gas pipe there is a calibrated gas orifice with an electronic differential pressure
transducer device.
Combustion and Control unit for 20 Ton/day furnace
Six zones combustion and control unit
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Falorni Gianfranco s.r.l.
www.falorniglass.com
Glass Industry
Recuperative Continuous Furnace with Gathering
design&construction in the glass world
Combustion
Systems
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TEMPERATURE CONTROL
The target temperature is set on the main controller that controls air and gas controllers.
Programs for different thermal cycles can be performed.
AIR CONTROL
The air controller controls the electronic Inverter that changes the speed of the fan. Fan
motor always runs at minimum speed. Then energy consumption and noise are minimum.
GAS CONTROL
The gas flow is controlled through the electric valve operated by the gas controller.
AIR/GAS RATIO
The system checks any time the proper quantities of gas and air to the burner.
1. Temperature controller
2. Gas controller
3. Air controller
4. Air flow transmitter
5. Heat recuperator
6. inverter
7. Air valve
8. Fan
9. Thermocouple
10. Gas valve
11. Main gas valve
12. Flexible joint
13. Filter
14. Gas reducer
15. Shut off valve
16. Gas flow transmitter
17. Gas controller
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Falorni Gianfranco s.r.l.
www.falorniglass.com
Glass Industry
Recuperative Continuous Furnace with Gathering
design&construction in the glass world
Oxygen/Gas
Combustion
system with
Flat Flame
Burners
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For the production of special glass with very high melting temperature, such as dark
color or borosilicate glass or ceramic glass or to increase the melting rate capacity of the
furnace, it is used a special automatic combustion system with pure Oxygen-Gas.
Depending on the furnace dimensions, two or three or four oxygen burners with
flat flame are installed on the sidewall of the melting tank.
The energy of the oxygen – gas flame is transferred directly on the glazed batch
with the flat flame burner. A large melting surface is covered by the flame and
it helps the furnace to reach very high temperature and to speed the melting
process.
With the Oxy-Gas combustion and control system we have the following advantages:
a. Shorter melting time: Thanks to the higher temperature of the flame and its
brightness, the melting process is much faster.
b. Melting of special glass: The high temperature of the flame allows to melt special
glass like bororsilicate and very dark colored glass.
c. Loss of chemical components: The quantity of waste gas is reduced of 85%, and
the batch powder carried out is lower.
d. Atmosphere pollution: The NOX emission in the atmosphere is reduced of 70% if
you calculate quantity of NOX per glass Kg.
e. Energy saving of 40 % compared with a traditional furnace gas fired with preheated air at 550°C
f. Melting Cost saving of 8-10% compared with a traditional furnace gas fired with
pre-heated air at 550°C.
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Falorni Gianfranco s.r.l.
www.falorniglass.com
Glass Industry
Recuperative Continuous Furnace with Gathering
design&construction in the glass world
Combustion
System with
Gas-Oxygen
Supplementary
Booster
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For the production of special glass with very high melting temperature, such as dark
color or borosilicate glass or glass ceramic, or to increase the melting rate capacity of
the furnace, it is used a special automatic combustion system with Oxygen-Gas booster
system.
One supplementary Oxygen burner is installed between the first air/gas burner
and the Dog house. The energy of the oxygen will be transferred directly on the
glazed batch to speed the melting process.
This system is an innovative pre-heated air/natural gas plus Oxygen Booster combustion
system conceived to work in two different operating ways: • Preheated air / natural gas (traditional way)
• Preheated air / natural gas Plus Oxygen Booster
It is studied to improve the following points:
a. Shorter melting time: Thanks to the higher temperature of the flame and its the
brightness of the oxygen Booster, the melting process is much faster.
b. Melting of Special glass: The high temperature of the flame allows to melt special
glass like bororsilicate and very dark colored glass.
c. Loss of chemical components: The quantity of waste gas is reduced of 35%, and
the batch powder carried out is lower.
d. Atmosphere pollution: The emission in the atmosphere is reduced.
e. Flexibility in the utilisation: The Falorni combustion system with Oxy Booster
can be used in the traditional way (preheated air/natural gas) and with air/gas plus
oxygen booster. The commutation is directly made from the panel control (turning
a key selector), and nothing has to be moved (the burner and the digital controller
instruments are both the same). The operator can change type of system every time
he wants, and he can use the Oxygen only during some special glass meltings ( for
example - Borosilicate glass - Dark colored glass). With this system it is possible to
use the Oxygen only when it is necessary. During the week end or low production
period, for example, it is not convenient to use Oxygen because it is not very
efficient.
f. Easy installation: The Falorni Oxy system is very easy to install, in comparison with
the standard combustion system. It is possible to add the oxygen technology to all
the Falorni combustion systems.
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Falorni Gianfranco s.r.l.
www.falorniglass.com
Glass Industry
Recuperative Continuous Furnace with Gathering
design&construction in the glass world
Combustion
Systems
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AUTOMATIC COMBUSTION CONTROL
All the main furnace process variables are automatically controlled by precision closed
loop controllers. The signals, derived from a comprehensive set of plant sensors, are
taken to a central control and instrumentation panel. Manual by-pass switches are
available for all variables for setting up or emergency use.
From the central control panel it is possible to start and check all the plant, both the
melting tank and the gathering bays or channels areas and spouts.
Control and instrumentation panel including:
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Operation selector and push buttons for the complete furnace (melting area,
pressure, glass level, gathering bays or forehearths).
Furnace temperature controllers (melting and refining) Eurotherm.
Gas flow digital controller Eurotherm.
Air Flow digital controller Eurotherm
Hot air digital controller Eurotherm
PLC Signal processors for alarm status acquisition (alarm call – alarm knowledge alarm restore)
Furnace Pressure controller
Glass level controller
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Falorni Gianfranco s.r.l.
www.falorniglass.com
Glass Industry
Recuperative Continuous Furnace with Gathering
design&construction in the glass world
Supervision
and Control
System
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All the main furnace process variables are automatically controlled by precision closed
loop controllers. The signals derived from a comprehensive set of plant sensors, are
taken to a central control and instrumentation panel. Manual by-pass switches are
available for all variables for setting up or emergency use.
It is essential to keep detailed records of all aspects of the furnace performance both to
ensure maximum efficiency and to monitor trends and alarms to provide early warning of
problems. A computer based data management system, the MOVICOM package,
performs this function.
The MOVICOM SYSTEM can be networked with existing plant computers if required.
No. 1 Supervision system including:
• no 1 PC for supervision and control
• no 1 19 inch color monitor
• no 1 PLC, signal processors / converters
• Temperature trend with 3 months recorder capacity
• Alarm status acquisition (alarm call – alarm knowledge - alarm restore)
• Operation status of the furnace components
• Management set-point and operator parameter of all the digital controller and
monitoring.
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Falorni Gianfranco s.r.l.
www.falorniglass.com
Glass Industry
Recuperative Continuous Furnace with Gathering
design&construction in the glass world
Hot Air
Burners
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Hot Air Burners for unit melter furnace. The internal part is covered with refractory
material and the maximum temperature of the air is 750°C.
On each burner, there is a butterfly valve with pressure manometer for hot air
regulation.
On each burner, Micrometric valve and mechanical gas flow meter for gas quantity
measure.
The gas mixer of the burners are adjustable in order to control the flame length. The
distance between air mixer and gas nozzle inside of the burner is adjustable, in order
to control the air gas mixing process.
The gas pipe with nozzle and air mixer are easily interchangeable from the back of
the burner
The burners can work with big excess of air to create a very oxidant atmosphere in
the combustion chamber.
Low noise burner. The combustion noise of these burners is very low.
The burners are installed on a fully adjustable bracket and connected to the gas
supplied through quick-release flexible hoses.
20 Tons/day glass melting Furnace
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Falorni Gianfranco s.r.l.
www.falorniglass.com
Glass Industry
Recuperative Continuous Furnace with Gathering
design&construction in the glass world
Continuous
Furnace Glass
Draining
System
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In the center of the glass melting tank throat, 25 mm lower than the electrofused cast
sole, there is a draining hole of about 35 mm diameter.
The drilled electrofused cast block is fixed 25 mm lower than the sole of the tank and its
tickness is 200 mm.
The drain opening is controlled by a steel water cooled plunger, installed with a
mechanical system.
The draining can be used for the complete emptying of the furnace or for taking out a
part of the glass for cleaning of the melting tank bottom.
During the glass drainage of the furnace, the glass flow from the furnace can be open
and close by the water cooled plunger mechanism.
CLEANING OF THE MELTING TANK BOTTOM:
In the bottom of the melting tank after the first year of furnace operation there is a
deposit of heavy glass.
This glass has a big contamination of zircon coming from the refractory material, and the
quantity of this glass has to be controlled in the life time of the furnace.
The way to clean the melting tank bottom is to open the drain for few minuts, disharging
50 – 80 kg of glass and closing it.
This operation has to be made every day for two weeks.
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Falorni Gianfranco s.r.l.
www.falorniglass.com
Glass Industry
Recuperative Continuous Furnace with Gathering
design&construction in the glass world
Glass Level
Control
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The glass level system with tip platinum probe, guarantees a 0,1 mm precision for
the variation of the glass level.
The Probe can be:
- High temperature steel water cooled probe, with tip in platinum of about 20 mm.
- Alumina probe, high temperature resistant with tip in platinum 20 mm.
• The Control of the Glass Level: The probe has a continuous alternate movement
(up and down). When the platinum tip of the probe touches the glass surface,
the electric circuit closes; the moment of the contact is underlined through a
potentiometer, that records the exact position in which this contact happened. The
probe stops suddenly and inverts the movement in order to avoid to plunge the
platinum tip into the glass.
• The signal coming from the potentiometer is converted from KΩ to mV, and sent to
a PLC.
• The signal is subsequently sent to a regulator/programmer Honeywell UDC 1002,
which shows on its display, the position of the glass in mm as regards the theoretical
zero.
• The output of the instrument which makes the level regulation is in 4-20 mA and is
connected to the regulation panel that drives the raw materials’ charging machine
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Falorni Gianfranco s.r.l.
www.falorniglass.com
Glass Industry
Recuperative Continuous Furnace with Gathering
design&construction in the glass world
Laser Ray
Glass Level
Control
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The device is composed by 4 units:
• Laser source unit;
• Receiver unit;
• Indication unit (display) and regulation (to be supplied under request);
• Terminal box unit;
METHOD OF MEASURING AND STRUCTURE
(CONSTRUCTION)
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In its melting state, the glass has a uniform and flat surface (smooth) and has
reflecting capacities. This capacity of the glass is exploited in the method of glass
level measuring without contact, with the help of the laser.
The laser ray, from the laser source unit, falls on the melting glass surface, with
an angle of 8-45 degrees, and it is reflected on the graduated line of the photoreceivers of the receiver unit. According to the glass level, the laser ray moves
along on the graduated line of the photo-receivers. The modification of the glass
level in the field of ± 10 mm, causes the movement of the laser ray of ± 20 mm
on the photo-receiver. The integrated processor processes the signal received and
calculates the glass level.
The scheme of the digital process of the glass level measurer LUR-4C signal,
allows to minimize the effect of external perturbation elements: vibration of forming
machines, flame tongues, electric perturbations.
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Falorni Gianfranco s.r.l.
www.falorniglass.com
Glass Industry
Recuperative Continuous Furnace with Gathering
design&construction in the glass world
Pressure
Control
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Complete furnace pressure metering and control system, including:
• Furnace pressure probe
• Sensor for atmospheric pressure measuring transmitter.
• Digital controller Instrument
• Electronic inverter
• Electric fan
• Air Jet damper
PRESSURE REGULATION SYSTEM
The control of the pressure is regulated by the inserting of plus or minus forced air, in
the waste gas exit pipe, after the recuperator. In this way we can reduce or increase the
speed of the waste gas and consequently the pressure inside of the furnace.
THE SYSTEM IS COMPOSED AS FOLLOWS:
The differential pressure value coming from the furnace pressure probe is received by
the pressure transmitter that trasforms it in electric signal and sends it to the digital
controller.
The automatic digital controller manages the air quantity (electric fan speed) through an
electronic inverter.
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Falorni Gianfranco s.r.l.
www.falorniglass.com
Glass Industry
Recuperative Continuous Furnace with Gathering
design&construction in the glass world
Recuperative
Continuous
Furnace with
Gathering
bays: batch
charger
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The furnace is provided with one “ DOG HOUSE “ with trapezoidal or rectangular shape
The batch is charged by one Falorni oscillating channel with water cooled pusher.
The machinery oscillation has two effects, discharging the batch in the Dog House
and pushing the batch in the melting area.
In details, the charging machine achieves: The complete covering of dog house; A
very good distribution of mixture on glass surface;
The machinery has the charging capacity from 10 to 40 ton/24h.
The Falorni batch charging machine is covered in the internal part of the hopper and the
pusher with very hard coating of 5 mm thickness of wear protection.
19
Falorni Gianfranco s.r.l.
www.falorniglass.com
Glass Industry
Recuperative Continuous Furnace with Gathering
design&construction in the glass world
Recuperative
Continuous
Furnace
Falorni
Proposal
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This short presentation is necessary to explain which type of experience we have in the
field of big plants construction.
The aim of Falorni company is to start to cooperate with big containers and tableware
producers on the basis of the long time experience we have in the Italian glass containers
market.
The list of accessories, services and complete plants we can supply is the following:
• Thermocouple R – S – B Type standard and special shape with different coating and
a big range of insulating cables
• Gas burners and accessories for End-fired regenerative furnaces and for Side-fire
recuperative furnaces
• Refractory and insulating materials for spare parts and special hot repair
• Batch charging machine with oscillating – rotating system till 460 tons / 24h
capacity, covered inside with very hard wear protection.
• Stirrer mechanism systems, for forehearths elimination of the cords
• Electric drain nozzle for high temperature constant draining of the heavy glass from
the bottom of the forehearth.
• Automatic combustion and control system for melting tank regenerative and
recuperative continuous furnaces
• Regenerator reversal system
• Air jet damper
• Automatic combustion and control system for forehearths.
• Glass level control systems
• Heat steel tube bundle recuperator for pre-heating of the air till 750°C
• Heat steel double shell recuperator for pre-heating of the air till 600°C
• Electric boosters for: MELTING BOOSTER, BARRIER BOOSTER, THROAT BOOSTER
• Regenerative End-fired glass melting furnaces
• Recuperative End-fired glass melting furnaces
• Recuperative Side-fired glass melting furnaces
• Recuperative flexible side –fired melting furnaces
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