Paths To Sustainability
The Search for Energy Efficiency
GMIC Energy Workshop
October 18, 2007
Energy Efficiency of Glass Furnaces and Application of Batch & Cullet Preheating
Ruud Beerkens, TNO Science & Industry,
P.O. Box 6235, 5600 HE Eindhoven, The Netherlands
This presentation will show the course of energy consumption and energy efficiency of glass furnaces in time (last century), and typical energy balances for different types of furnaces are given:
Regenerative container glass furnaces;
Regenerative furnace with batch & cullet preheating;
Oxygen fired furnaces;
Oxygen fired furnaces with batch / and or cullet preheating.
The effect of changes in process conditions on energy consumption of glass furnaces will be shown and the features of the most energy efficient furnaces (from benchmark analysis) in the container glass industry will be presented. Today, the most efficient container glass furnaces consume (depending on cullet % in batch) about 3.6-4 GJ/metric ton molten glass (IS units). With batch preheating even lower values may be achieved.
In the European container glass industry, batch and/or cullet pre-heaters are applied in 8 cases. In all cases the cullet level in the batch exceeds 50 %. The first pre-heaters have already been installed in the mid-eighties, thus the glass industry in Europe has 20 years experience with these installations, which have been optimized in time.
In Europe, 3 different types of pre-heaters are installed in the container glass industry:
Direct-contact cullet plus batch pre-heater, batch and cullet exposed to flue gases from regenerators by the gas flowing in the pre-heater through half-open channels;
Direct-contact cullet pre-heaters (only cullet);
Pre-heaters with separated channels for flue gases and batch plus cullet, batch and cullet moving through narrow vertical channels and preheated by flue gases flowing in neighboring channels and separated by metal walls.
The different preheating systems will be shortly introduced and actual experiences with these pre-heaters will be discussed. Maintenance, energy savings realized, typical costs and additional features, such as effect of the application of direct-contact preheating systems on emissions will be shown.
Acknowledgements: Dr. H.-J. Barklage-Hilgefort, Ir. Sven Kahl, Dr. M. Lindig
Keywords: energy efficiency, batch preheating, energy saving methods, energy balances
Intelligent Glass Melting Concept (IGMC)
Fiction or Reality?
Josef Chmelar, Glass Service Inc., Vsetin, Czech Republic
Erik Muijsenberg, Glass Service B.V., Maastricht, The Netherlands
Glenn Neff, Glass Service USA, Inc., Stuart, USA
In the past 10 - 15 years there has been an ongoing discussion about what the next “big” step in new melting concepts and glass furnace design innovations will be. Significant efforts have been made in the development of the New Generation Melter concept such as recent DOE funded projects. New revolutionary furnace designs, although interesting, are difficult to be quickly utilized by large scale glass production due to the high technological / financial risks.
Another method of a melting process improvement is based upon evolutionary furnace improvement, new materials, process data gathering and advanced control concepts. Such an evolutionary process is seemingly less innovative; however, it brings incremental benefits in the process efficiency without significant financial and management risks.
Furnace design can be very effectively improved by advanced furnace modeling to meet the specific needs of particular plant operation. In order to keep high quality and efficiency of such design, a network of advanced sensors in combination with an advanced control system can be adopted.
The Intelligent Glass Melting Concept is based upon two principal parts. First, precise data gathering by the furnace innovative field sensors (O2 probes, mass spectrometer on-line analysis, LIBS, batch image analysis, glass quality analysis) in combination with more conventional sensors (thermocouples, flow meters, pressure gauges) is required. Second, on-line production data needs to be collected and processed by an Expert System (a Model Predictive Control type of system) using rules and advanced predictive numerical methods to control the production unit.
Such a combination of relevant and reliable data from the furnace with Advanced Predictive Control algorithms helps to utilize a given furnace design to its maximum technical capability.
Practical examples of such an approach will be shown with real glass production data.
Economic & Environmentally Advantageous Glass Batches Formulated with Spodumene
Dagobert Thiery*, Olivier Dubois*, Anand Sheth**, Derek J McCracken***
* OTAVI Minerals, Bockholtstr. 129, D-41460 Neuss, Germany
** Talison Minerals Pty Ltd., Level 3, 30 Esplanade, Perth Western Australia 6000
*** Prince Minerals, 14 East 44th Street, Fifth Floor, NY 10017
It is an inconvenient truth that green house gas emissions from human civilization will have an impact on climate change. The cost for energy in form of electricity, natural gas and fossil fuel has been rising in recent years and is expected to increase further. The energy cost of 15-20% is a significant part of overall glass manufacturing cost.
Therefore any technical development contributing to savings in energy and combustion gas is of interest.
In general, around 75% of the energy for glass manufacturing is used in the melting process.
A saving in specific energy required to melt a unit of glass (GJ/1000Kg), will reduce the consumption of fuel and consequently the emissions on CO2 and NOX.
The other issue, environmental, is related to the exhaustion of Boron particulates generated through the evaporation of Boron silicate glass melts.
The use and substitution of hazardous raw materials such as Lead oxide (PbO) for certain lighting and crystal glasses is also an environmental aspect affecting the glass maker.
Linked to above environmental concerns are the consideration and their impact on overall production costs. The specific cost per unit or weight of final glass product is a useful bench mark parameter. Any improvement in process efficiency through pull or melt to pack would be reflected as well as the specific energy (GJ/tglass) reduction.
In addition to process technology optimization, the chemical reformulations of glasses are bearing the potential to contribute to overall improved production efficiency.
This paper discusses how Lithia, Li2O, provided by Spodumene, LiAlSi2O6 , can be of main and manifold function in glasses even at low concentration of 0.1-1% Li2O. These are discussed for specific cases and glasses under the above described environmental and economic concerns. These glass batches have shown to reduce 3-10% in energy consumption, about 4% in combustion gas emissions and increase in the melt to pack ratio by 2-10%, thus achieving improvement in the process efficiency.
Heat Recovery Examples at SISECAM
Levent Kaya, Sisecam, Istanbul ,Turkey
Raising steam by waste gas from glass melting furnaces is the most common and the cheapest way to exploit waste gas energy. But, this recovered energy in the form of steam cannot be directly coupled to glass production process, and its use is limited to space heating applications in most cases. Also, the seasonal demand for heating prevents making use of the installed capacity of the heat recovery unit throughout the whole year.
At Sisecam, along with widespread use of waste heat boilers that meet space heating demand in winter times, there are other applications of the recovered heat that are directly linked to production. One example is utilizing waste heat to run absorption coolers to supply chilled water for the fiber-winding stations’ air-conditioners that help stabilize winding process. Another application is the electricity generation by a steam turbine using float furnace waste gas. This way, the recovered energy in the form of electricity is directly returned to production process.
Heat Recovery on a Float Furnace
Niels A. Rozendaal - OPTIMUM Environmetal & Energy Technologies b.v.
The generation of 21 barg (2100 kPa or 320 PSI) steam using the flue gasses of a float furnace as heating medium with in-line boiler cleaning and no cleaning stops.
OPTIMUM will present its heat recovery system as a case study of an industrial project:
A well known Dutch glass manufacturer operates a float furnace for the production of flat glass. OPTIMUM installed a specially designed fire tube waste heat boiler with Automated Pipe Cleaning System (APCS) in-line cleaning to recover the heat from the furnace. The APCS is a patented technology developed by OPTIMUM to keep the heating surface of boilers clean without the need to stop the system for cleaning.
The boiler has a steam capacity of 10,000 kW (34 MM BTU/hr) and has currently been in operation for over 8 months without stops. The heat recovery system has a relative constant pressure drop and is not negatively influencing the furnace. The return on investment was significantly less than a year. Since the heat recovery system showed to be reliable and has a high availability the next step in the project is going to be to install a steam turbine gen set to generate electrical power.
Visual Intelligent 3-D Temperature Analysis System
Dr. Rodney Rossow and Dr. Shahla Keyvan
Enterprise Energy & Research
EE&R is commercializing a product for saving energy in gas-fired high temperature furnaces used in the glass industry. This product is called Visual Intelligent Temperature Analysis System (VITAS) and provides 3-D temperature profiling and flame analysis. VITAS provides feedback for the furnace control (either automatic or manual). Minimizing fuel consumption by avoiding operation above minimum required temperature results in the energy savings which is estimated to be in the 5%-10% range.
Other benefits of this system are pollution reduction and improvement in the product quality. VITAS is packaged as a water-cooled periscope that allows the viewing of the internal furnace environment by a visible-range camera and the subsequent analysis of the image by a computer system benefiting from artificial intelligence and vision technology. Through a lease-to-own program arranged by EE&R, VITAS will be offered to the customers at no charge. Upon installation, the customer will only pay a fraction of its monthly energy savings. After a few years, the customer will own the VITAS system free and clear, and will start pocketing the full monthly savings.
Energy, Sustainability and the Glass Industry
Dan Wishnick, John Salkas, Siemens Energy & Automation
The glass industry faces many challenges related to becoming more efficient both from an energy and productivity standpoint. These challenges include the effects of globalization, rising energy costs and CO2 issues, and how the industry will remain relevant in terms of innovation. In order to overcome these challenges we strive to look at the entire process as one rather than as islands. This presentation will review the role of automation and sensors in an integrated approach to energy reduction. In addition, waste heat recovery will be discussed as another technique to mitigate the rising cost of energy and to enhance environmental sustainability.
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