Electric Forehearth
Colorant F/H
IR Thermometer
Level Control
M.H.E.
Thermocouple
VSF Cooling
Where Installed World-Wide
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Summary of the Benefits:
- Improved glass homogeneity
- Better glass temperature stability
- Quicker response to forehearth entry temperature changes
- Rapid stabilisation after a production change
- Savings on fuel consumption
- Simplicity of operation, minimal set up and maintenance
- Re-use of up to 80% of roof blocks at the first rebuild, depending on the type of glass and the operating history of the forehearth
and simplicity of operation and control, the BH-F 400 Series has proved
to be a major advance in forehearth design and performance.
This proven technology is now well established with over 700 installations
in most of the major glass production sectors, including containers,
tableware, lighting, flat glass and fibreglass
and in most of the glass producing countries of the world.
In the conventional design of forehearth:
combustion gases and cooling air both entering from the sides.
This is inherently inefficient since they mix so that
the effect of both is diluted.
The result is that the hot centre stream of glass is not cooled down
preferentially to the cooler side wall glass.
Multiple exhaust holes can allow rapid and uncontrolled escape of gases
and cooling air and cold air can be drawn in through gaps in the
superstructure. Complex roof constructions, with multiple blocks
and side cooling ducts, do not allow good insulation.
The combination of these factors can lead to temperature problems,
reduced glass quality and large amounts of fuel being wasted.
The 400 series forehearth design is based on the thermodynamic
requirements of good glass conditioning.
Glass, as it flows, looses heat from the sides, which slows down,
leaving a faster moving core of hotter glass.
This is compensated for in three ways; graded insulation,
centreline cooling and side heating.
By selectively placing different grades of insulation around the channel,
heat losses can be better controlled.
The monobloc roof is set close to the glass surface and has a
central cooling channel on the under side. Cooling air, if required,
is fed from a single inlet per zone along this centre channel directly
above the hot centre stream of glass precisely where is it needed.
The air exhausts, with the products of combustion through
a single flue in each zone.
note:
The air cools the underside of the roof and the reduction in
re-radiation cools the glass. Cooling air does not come in to
contact with the glass surface.
The heating is concentrated along the sidewalls ensuring that
combustion and cooling systems are separated
and therefore more effective.
This unique combination of features provides a highly regulated
environment where heating and cooling can be automatic controlled
to achieve stable and homogeneous exit temperatures with greatly
reduced gas and cooling air consumptions.
We have seen fourfold reductions in temperature gradients,
60% reductions in gas consumption and 85% reductions in cooling air.
The forehearth also responds faster to incoming temperature changes
and stabilises more rapidly after a production change - two to threefold
reductions in job change recovery times have been reported
(from the start of production to establishing normal production efficiency).
Increased production speeds and pack rates have also been achieved.
Additional features include HP firing and VSF cooling and combustion.
The innovative gas firing system has a high turndown ratio
that can achieve, at high pulls, additional fuel savings.
In addition, very high heat inputs are possible allowing a more
rapid heat-up at job changes.
Variable speed fans (VSF) on the cooling and combustion systems
remove the need for valves, linkages and actuators, thus improving
controllability, simplifying the set up and reducing maintenance.
The linear and stepless response of the inverters,
with their digitally stored setting,
ensures the optimum match with modern control systems that remains
reliable through the whole production campaign.
The Backup
BH-F’s advanced computer aided design facilities enable usto make fast and accurate proposals covering all aspects of
the glass manufacturing process, from throat to forming machine.
Our design teams ensure that customers get the equipment and materials
which best suit their own particular production requirements,
with swift and precise assessment of performance.
In the field, our engineers operate worldwide to
install and commission equipment, earning a reputation both
for technological expertise and for service.
BH-F encourages customers to arrange follow-up visits
after a period of operation to ensure installations are
performing to the high standards demanded of all BH-F equipment.
A training engineer is available to train your staff
in all aspects of forehearth set up, operation and maintenance.
With our track record of technical innovation, expert consultancy
and technical support, BH-F provides a unique level of service to glass.
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