Glass Melting Technology: A Technical and Economic ... - OSTI

or long-term trends and judges the rate of change for parameters, primarily refractory and glass temperatures.
Through experience, a furnace operator knows why a condition changes and how the furnace responds. By
comparing actual to expected energy input, the operator determines which compensations are required for
the furnace to return to normal operation. See Table 2.1 for Key Performance Indicators (KPI).
Table 2.I. Key Performance Indicators (KPI)
KPI PARAMETERS
Energy Gas Electric Compressed Furnace Forming Tons/Day Energy/Ton
Utilization Utilization Air Energy Energy
Efficiency Efficiency Utilization
Efficiency
Efficiency Efficiency
Emissions NOx SO2 HCL Particulate CO2 Emissions Total
Cost Emissions
Plant Conversio Reject Maintenanc Operating $Orders/To Energy/To Emissions/Ton
Summary n Ratio Efficiency e $/Ton Cost/Ton n Produced n
Plant Raw Labor Energy Emissions Capital/Ton Allocation
Costs Materials
Effective energy management in furnace control influences the economics of operating a glass furnace and
the consistency of the glass-product quality. Each furnace and glass type has a quantifiable energy
characterization curve that defines operating energy versus pull rates and cullet levels. Once defined in
operation after a furnace rebuild, expected and actual fuel inputs, temperatures, and glass quality can be
compared to determine how to adjust energy input.
The furnace locations where temperature measurements are of particular interest to operators include:
• Melter, refiner/distributor, regenerator crowns (Thermocouples (TCs) using optical sensors);
• Melter and refiner bottoms in or near glass using temperature controllers (glass bath pyrometers);
• Bridgewall with optical sensors and temperature controllers;
• Gradient profile with portable optical sensors, TCs (crown/bottom), hot spot optical;
• Regenerator with top checker optical sensors (wide-angle view, crown and rider arch TCs;
• Exhaust flues and stack with TCs.
As the level of sophistication increases, long-term data storage, trending analysis and other data become
more important for monitoring of and intervention in the process. It has become common practice to rate
furnace performance against established standards, such as energy consumption and costs. To control basic
functions, which do not normally vary, key furnace operating parameters are followed; other control aspects
are changed to maintain relationships between tonnage and temperature schedules. With instrumentation,
changes can be addressed in production rates, cullet percentages, equipment breakdowns and melting trends.
Comparison of actual to expected energy input could determine which compensations are required to return
furnace operation to normal.
European experience
To relate the energy savings and cost savings of process control or automation for melting processes would
be difficulty as no accurate values are available on the exact impact of automation for glass melting
processes on energy consumption and cots since there are direct (lower energy consumption/ton glass melt)
and indirect (lower glass container weights, production efficiency improvement) energy savings.
However, to predict energy savings that might be accrued by the US glass industry, the experience of the
European glass industry in the Netherlands provides some indicators. For the whole glass process, five to six
percent energy efficiency improvement has been realized for the period (1989-2000) from increased yield,
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