|
|
|
| |
 |
| |
|
 |
|
A review of Supplemental Oxygen Methods
for Glass Melting
Increasing the amount of Oxygen in air from its initial 21%
significantly increases the flame temperature achieved with
any fuel. For example, natural gas burned in air has a flame
temperature of 3520 °F while the flame temperature of
natural gas burned in 23% O2 is 3640 °F.
This effect is shown in figure below.
|
| |
 |
| |
| Higher flame temperatures in the glass furnace
improve the heat transfer to the batch and glass. This is due
to the fact that all three heat transfer mechanisms, conduction,
convection, and radiation, are flame temperature dependent: |
| |
|
| |
| Conduction: |
Q µ (Tf - Tp) |
| Convection |
Q µ (Tf - Tp) |
| Radiation |
Q µ (Tf
- Tp) |
| |
|
| where: |
Tf = Flame Temperature |
| |
Tp = Product (Lime) Temperature |
| |
| At glass melting temperatures radiation is the
dominant mode of heat transfer. The heat transfer rates for
conduction and convection are linear with the difference between
the glass and the flame temperature. The heat transfer rate
due to radiation is proportional to the difference between glass
and flame temperature, each raised to the fourth power. Oxygen
increases the flame temperature, which greatly increases radiation,
the already dominant mode of heat transfer. Thus with oxygen
enrichment, more heat is absorbed by the product, less heat
is lost in the exiting combustion gas, and the combustion process
becomes more efficient. |
|
| |
|
| |
| Oxygen Enrichment: |
| |
 |
| |
| With this technique, oxygen is injected into the
main combustion air header well ahead of the delivery point
to the furnace. This pre-mix of oxygen is most common on recuperative
furnaces or unit melters that have many such delivery points
(hot or cold air burners) or on regenerative melters where it
is desirable to use the oxygen to enhance the entire combustion
process in a consistent manner. Experience is needed to deliver
the right amount of heat to the right zones and to ensure safe
application of the Oxygen |
|
| |
|
| |
| Oxygen Lancing: |
| |
 |
| |
| This method has historically been the most cost-effective
way to use oxygen to supplement air-fuel combustion. The strategic
injection of oxygen beside, beneath or through air-fuel flames
has allowed glass melters to reach campaign objectives in terms
of pull rate, fuel efficiency and glass quality. The benefits
of oxygen lancing accrue from having the oxygen mix with fuel
where it is most needed; namely in oxygen-starved areas of the
combustion space or in the under-side (glass surface side) of
the air-fuel flames where flame temperature has the greatest
impact on heat transfer to the melt. Knowing how many lances,
where to place them and flow rates to use, allow us to deliver
the most cost effective solution. |
|
| |
|
|
|
|
Oxygen Boosting:
This method of using supplemental oxygen is relatively new
to glass manufacturers and has been enabled by the emergence
of superior oxy-fuel burner offerings developed for the 100%
oxy-fuel conversion of melters. The boosting concept uses
oxy-fuel burners positioned within the air-fuel melter to
increase production, quality, efficiency and furnace stability.
Depending on the needs of our customers we can tailor the
operation to deliver the benefit(s) desired. Oxy-fuel boosting
is typically used to increase pull rate on a furnace that
is at capacity or that has been crippled due to a failure
or loss of effectiveness of the air-fuel combustion system.
Payback for the technology is often less than three months.
The advantages of our boost technology are so significant
that many furnaces, which used Air Products' boost at the
end of the previous campaign to address furnace limitations,
are rebuilt and come on-stream using boost.
|
| |
 |
| |
| Here, the high temperature flames of oxy-fuel
combustion are placed over the cold batch to create a tremendous
amount of heat transfer. The result is early batch glazing and
significantly enhanced melt run-off; this superior melt rate
then allows for an increase in production or a reduction in
over all fuel.Talk to us to find out which of these, or other,
techniques is right for you. We continue to develop new technologies
to improve glassmaking. |
|
| |
|
|
|
