S. K. Sundaram

79th Conference on Glass Problems

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Foreword

x

PLENARY SESSION

Mathieu Hubert and Irene Peterson

Cullet Supply Issues and Technologies

15David M. Rue

Towards the Path for De-Carbonization-Understanding Legislative Challenges

Jim Nordmeyer

65Dry Sorbent Injection System Optimization and Cost ReductionPotential Through Data Analysis

Gerald Hunt, Ian Saratovsky, and Melissa Sewell

79th Conference on Glass Problems

v

Contents

55

3Challenges and Progress in Understanding Glass Melting

Glass Surface Modifications for New Products in the 21st Century J.W. McCamy, A. Ganjoo, and C-H Hung

Flat Glass Manufacturing Before Float Luke Kutilek

37

29

MELTING AND COMBUSTION

87Model Predictive Control and Monitoring of the Batch Coverage andShape, and Its Effects Upon the Crown Temperature. Can this beCorrelated to the Overall Glass Quality and Stability in a GlassFurnace? Erik Muijsenberg, Robert Bodi, Menno Eisenga, and Glenn Neff

Preface xi

Acknowledgments xiii

101Optimization of Energy Efficiency, Glass Quality and NOx Emissions in Oxy-Fuel Glass Furnaces Through Advanced Oxygen Staging

Mark D. D’Agostini, and Bill Horan

Staged, Oxy-Fuel Wide Flame Burners to Mitigate Refractory Port

Gaurav Kulkarni, Uyi Iyoha, Shrikar Chakravarti, Patrick Diggins III, Arthur Francis, and Gregory J. Panuccio

141 INNOREG: Going Beyond a Well-Known Solution for ThermalRegenerators

Stefan Postrach and Elias Carrillo

157Digitally Mapping the Future of Glass Furnaces with LasersBryn Snow, Crawford Murton, Corey Foster, and Ulf Hermansson

SORG 340S+® Forehearths - Improvements and Operational Data Rüdiger Nebel

Industry 3.9 Thermal Imaging Using the Near Infrared Borescope

N. G. Simpson, S. F. Turner, and M. Bennett

169

177Energy Recovery with a New Type of Tin Bath CoolerWolf Kuhn, Peter Molcan, and Stephane Guillon

125

Fouling and Foaming in Glass Furnaces 117

151 Advanced Post Mortem Study, From Digital Survey to Micro Scale Analysis

Emile Lopez, Jean-Gaël Vuillermet, Isabelle Cabodi and Michel Gaubil

Chemical Strengthening of Silicate Glasses: Dangerous and Beneficial Impurities

Vincenzo M. Sglavo

(NIR-B)

REFRACTORIES

ENVIRONMENT

Operating Experience with the OPTIMELT™ Heat Recovery

M. van Valburg, F. Schuurmans, E. Sperry, S. Laux, R. Bell, A. Francis, S. Chakravarti and H. Kobayashi

Technology on a Tableware Glass Furnace 201

191

79th Conference on Glass Problems

213Continuously Measuring CO and O2 to Optimize the CombustionProcess

Lieke de Cock, Vincent van Liebergen, and Marco van Kersbergen

219 Mitigation Options for Respirable Crystalline Silica: EngineeringControls vs. Personal Protection

Kyle Billy

227Carbon DioxideFuture of Glass Melting in a World with Stringent Reductions of

Stuart Hakes

79th Conference on Glass Problems

Foreword

79th Conference on Glass Problems

The 79th Glass Problem Conference (GPC) is organized by the Kazuo Inamori School of Engineering, The New York State College of Ceramics, Alfred University, Alfred, NY 14802 and The Glass Manufacturing Industry Council (GMIC), Westerville, OH 43082. The Program Director was S. K. Sundaram, Inamori Professor of Materials Science and Engineering, Kazuo Inamori School of Engineering, The New York State College of Ceramics, Alfred University, Alfred, NY 14802. The Conference Director was Robert Weisenburger Lipetz, Executive Director, Glass Manufacturing Industry Council (GMIC), Westerville, OH 43082. The GPC Advisory Board (AB) included the Program Director, the Conference Director, and several industry representatives. The Board assembled the technical program. Donna Banks of the GMIC coordinated the events and provided support. The Conference started with a half-day plenary session followed by technical sessions. The themes and chairs of four technical sessions were as follows: Melting and Combustion

Jan Schep, Owens-Illinois, Inc., Perrysburg, OH, Uyi Iyoha, Praxair, Inc., Peachtree City, GA, and Michelle Korwin-Edson, Owens Corning Science & Technology Center, Granville, OH Refractories

Laura Lowe, Harbison Walker International, Batavia, OH and Larry McCloskey – Anchor Acquisition, LLC, Lancaster, OH Forming

Adam Polcyn, Vitro Architectural Glass, Cheswick, PA and Kenneth Bratton, Bucher Emhart Glass, Windsor, CT Environment Glenn Neff, Glass Service USA, Inc., Stuart, FL and hil Tucker, Johns Littleton, CO

Preface

x79th Conference on Glass Problems

This volume is a collection of papers presented at the 79th year of the Glass Problems Conference (GPC) in 2018. The GPC continues the tradition of publishing the papers that goes back to 1934. The manuscripts included in this volume are reproduced as furnished by the presenting authors, but were reviewed prior to the presentation and submission by the respective session chairs. These chairs are also the members of the GPC Advisory Board. As the Program Director of the GPC, I am thankful to all the presenters at the 79th GPC. This year’s meeting was a great success with a total of 533 attendees including 29 students. I appreciate all the support from the members of Advisory Board. Their volunteering sprit, generosity, professionalism, and commitment were critical to the high quality technical program at this Conference. I also appreciate continuing support and strong leadership from the Conference Director, Mr. Robert Weisenburger Lipetz, Executive Director of GMIC and excellent support from Ms. Donna Banks of GMIC in organizing the GPC. I look forward to continuing our work with the entire team in the future. Please note that The American Ceramic Society and myself did minor editing and formatting of these papers. Neither Alfred University nor GMIC is responsible for the statements and opinions expressed in this volume. S. K. Sundaram Alfred, NY March 2019

Acknowledgments

xiii79th Conference on Glass Problems

It is my great pleasure to acknowledge the dedicated service, advice, and team spirit of the members of the GPC AB in planning this Conference, inviting key speakers, reviewing technical presentations, chairing technical sessions, and reviewing manuscripts for this publication: Kenneth Bratton - Bucher Emhart Glass, Windsor, CT Martin Goller - Corning Incorporated, Corning, NY Uyi Iyoha – Praxair Inc., Peachtree City, GA Michelle Korwin-Edson - Owens Corning Science & Technology Center, Granville, OH Robert Lipetz - Glass Manufacturing Industry Council, Westerville, OH Laura Lowe – HarbisonWalker International, Batavia, OH Larry McCloskey – Anchor Hocking, Lancaster, OH Glenn Neff - Glass Service USA, Inc., Stuart, FL Adam Polcyn – Vitro Architectural Glass, Cheswick, PA Jan Schep – Owens-Illinois, Inc., Perrysburg, OH Elmer Sperry – Libbey Glass, Toledo, OH Christopher Tournour – Corning Incorporated, Corning, NY Phillip Tucker - Johns Manville, Littleton, CO James Uhlik – Toledo Engineering Co., Inc., Toledo, OH Justin Wang – Guardian Industries Corporation, Geneva, NY Andrew Zamurs – Rio Tinto Minerals, Greenwood, CO Finally, I am indebted to Donna Banks, GMIC for her patience, support, and attention to detail in making this conference a big success and this Proceedings possible.

PLENARY SESSION

CHALLENGES AND PROGRESS IN UNDERSTANDING GLASS MELTING Mathieu Hubert and Irene Peterson Corning Research and Development Corporation Painted Post, NY, USA ABSTRACT

Glass is one of the oldest materials manufactured by mankind. However, many aspects of the reactions that convert batch materials to the melt are still only partially understood. Improvements to fundamental understanding on how different batch material characteristics, tank process variables and atmosphere control the melt evolution are needed to allow industry to produce high quality glass in the most efficient way, while reducing environmental impact. Recent improvements in measurement techniques have driven progress in understanding of the reaction pathway and kinetics of the batch- to -melt conversion on the laboratory scale. The development of advanced computing tools has increased the ability to visualize heat and mass flow inside the production tanks on the macro-scale. However, significant gaps remain in the ability to scale up experimental results from small-scale testing to production, availability of robust in-situ measurements for production tanks, and in incorporation of experimental data on the batch-to-melt conversion into mathematical models of glass production. INTRODUCTION

For millennia, highly skilled craftsman improved glass quality through their choices of batch materials, mixing methods and thermal treatments. Advances in technology were closely guarded secrets. More recently, this responsibility has shifted to scientists and engineers. Sharing of information between academia, industry and national laboratories disseminates improvements throughout the world. Advances in techniques for measurements and calculations have led to tremendous improvements in glass quality, expanded the breadth of chemistries produced, and improved the efficiency of energy utilization. Quality, as measured by visible bubbles and seeds, inhomogeneity, surface staining and durability have improved significantly, along with product yields – while energy requirements and furnace emissions have decreased [1].

A large and growing number of experimental techniques are in use to follow, quantify and understand the effect of batch material chemistry and particle geometry, heating and cooling profiles, oxidation state and furnace atmosphere on glass formation. Because of the multi-scale, interactive and complex nature of the batch-to-glass conversion process in a production tank, a variety of different techniques are used together to illuminate different parts of the process. This paper, while not meant to be a comprehensive review, will discuss a few of the methods in most common use, and present some recently developed techniques.

Because of the multiple variables at different scales that control the melting process, modeling is a critical part of building a useful and practical understanding of melting behavior. The ultimate goal is to use data gathered in the lab to build new math models, which would be able to combine the effects of the different variables from the micro-scale to the tank scale to find the best melting solutions.

A MULTISCALE CHALLENGE The conversion of a mixture of raw materials into a homogeneous melt involves a large

number of different and interacting variables which act on scales from the microscopic to the tank. The same final carbonates or minerals can be used as an alkali source. Each batch material powder has a size distribution and a particle shape. The primary particles of a batch material can be agglomerated by spray drying, or particles of different materials can be mixed and compacted into pellets or briquettes. A typical glass melting batch will include major components that make up a relatively large proportion of the batch, minor components to adjust the properties of the glass, and additives in very small amounts to assist fining and control the oxidation state. For example, a soda lime silicate batch can contain sand as 50-75 weight % of the total, minor additions of soda ash and limestone, and additives such as sodium sulfate for fining (typically < 1 wt%), nitrate as an oxidizing agent, or coke as a reducing agent (usually <0.5 wt%). Despite their small percentages, additives that control the oxidation state of the melt have a considerable impact on fining behavior [2] and the color of the glass. The redox state of the melt changes its heat transfer behavior and thermal profile in the melting tank, and thus the energy required to melt a given glass; more details are given in [3]. As shown by this example, changes to any of the batch materials can have unforeseen and far-reaching consequences for the rest of the process.

The batch materials undergo a complex sequence of reactions on the pathway to forming a liquid. An example of this sequence was given by Hrma, Kruger, and Pokorny [4]:

Water evaporation Gas evolution Melting of salts Borate melt formation Reaction of borate melt with molten salts and amorphous solids Precipitation of intermediate crystalline phases Formation of continuous glass-forming melt Growth and collapse of primary foam Dissolution of residual solids Formation of secondary foam

A variety of experimental methods are used to study specific stages and aspects of the batch-to-melt conversion at different scales from microscopic to macroscopic. Visual observation, either in-situ using a side view furnace, or by melt-and-quench methods are a useful first step. Gas formation and release can be studied using Thermo-Gravimetric Analysis (TGA), Differential Scanning Calorimetry (DSC) and Evolved Gas Analysis, with FTIR or Mass Spectroscopy attachments. Phase evolution can be measured using x-ray (XRD) and neutron diffraction techniques. The evolution of the microstructure of the reacting batch can be observed using x-ray tomography. In this paper, these methods will be briefly discussed, along with their advantages and limitations.

However, the conditions under which the batch reactions occur in a tank are dramatically different than in a crucible. A schematic of the furnace interior is shown in Fig. 1. The batch is introduced into the furnace on top of the molten glass, and is heated from above by heat transfer from combustion flames, and from below by heat transfer from the glass melt. As the batch heats

up, it undergoes a complex series of reactions which are controlled by kinetic and thermodynamic factors, and heavily influenced by both tank design and process setup. Because of all the interacting variables, computer modeling is critical to understanding tank behavior. Currently, modeling of the batch-to-melt conversion is still in an early stage of development, and the measurements from the tank that are needed as input are difficult to obtain.

Figure. 1. Schematic of heat and mass behavior inside a furnace VISUAL OBSERVATIONS

Visual observation is a useful first step towards understanding batch reactions. The batch free time (BFT) experiment is a simple and commonly used approach (see [5]). In BFT experiments, a standard quantity of batch can be heated either isothermally or following a desired time-temperature profile. Samples are removed from the furnace after different amounts of time, quenched and analyzed using an optical microscope. The amount of time required for all the solid material to dissolve under a particular set of conditions is called the “batch-free-time”. This approach is very useful for studying the effects of different types of sand, or different amounts of cullet. For example, the effect of adding cullet as particles or as briquettes on melting behavior of a soda-lime-silicate batch was studied by Deng et al [6]. In Batch A, the cullet was added as powder (as 84.5 wt% in the batch), while in Batch B, some of the cullet was added as a briquette (15 wt% added as briquettes made from fine cullet particles). Batches were heated up at 4° C/min then held at the indicated temperature for 4 hours before quenching. The samples were annealed and then cross-sectioned, and are shown in Fig. 2. At temperatures above 1200°C, the two batches showed similar melting behavior.

Figure 2. Effect of adding cullet as either fine powder or as briquettes on melting behavior. Reproduced from [6] with permission of Wiley.

The effects of different types and amounts of fining agents can be studied using the same technique. Samples containing differing kinds of fining agents are heated under the same conditions, then quenched. The minimum amount of time needed under a given set of conditions to remove all the blisters, called the “bubble-free time” can be used to compare the behavior of different fining agents. The size distribution and number of blisters, and the gases present inside them can also provide useful guidance about fining behavior.

These melt-and-quench experiments are very flexible. They can be performed using a variety of different batch sizes, from grams to kilograms, and are inexpensive and simple to perform and analyze. Different laboratories use different variations of this test: some melt from batch starting at room temperature and heat the batch at a constant rate, others put batch on top of a glass melt at high temperature and run the test isothermally. A variety of different crucible materials are used, including platinum and alumina. The main purpose of these tests is to compare the effect of different parameters (batch, temperature, time) on the batch-to-melt conversion in a qualitative way. The Technical Committee 18 (TC 18 – Melting, see [7]) of the International Commission on Glass (ICG) is currently working on a Round Robin comparison of batch free time experiment techniques at different laboratories around the world, starting from the same raw materials and using the same quantity of batch. The goal of that Round Robin is to develop a single simple laboratory procedure to evaluate the melting behavior of glass

However, these tests all have the same weakness; they are “ex-situ” and only offer snapshots of the evolution of the batch-to-melt conversion. High temperature melting observations systems such as the one described in [8, 9] allow direct observation of melting reactions in-situ. In-situ observation is typically used to investigate the impact of raw material selection and batching method (i.e. fine vs coarse batch vs pellets/briquettes – see for instance [8]) on the melting behavior. Because larger amounts of batch are usually used in the in-situ observation systems, the impact of minor components can also be seen more easily. Figure 3 shows the effect of adding a small amount of coke to one of the batches. The impact of this minor component on the foaming observed in the melt is clearly visible.

Figure 3. High temperature image showing the difference in foaming behavior of a base case glass and the same glass with small addition of coke. Reproduced from [9], with permission of Wiley.

The gases evolving from the melt during the in-situ observation experiment can be

analyzed using an in-line gas analysis system, as shown by the graph in Fig. 4. The combination of visual recording with simultaneous analysis of released gases enables a deeper understanding of the reactions. This is particularly useful for studies of foaming and fining mechanisms in glass melts.

Figure 4. CO2 evolution for a batch melted as coarse (base) batch, fine batch, and fine batch made into briquettes. Reproduced from [8] with permission of Wiley.

Although the in-situ observations provide important clues about the effects of different

variables on melting behavior, these are still static experiments on a small scale. In contrast, melting furnaces are dynamic, continuous systems on a much larger scale. One should always

remain cautious about parameters and scaling effects from a melting furnace that cannot be duplicated at the lab scale. WEIGHT LOSS AND ENERGY FLOW

The temperatures where important reactions take place, and the changes in mass and energy that occur during these reactions can be measured using Differential Thermal Analysis (DTA) or Thermogravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC) TGA/DTA measures changes in mass during a thermal cycle (usually during heating at a constant rate from room temperature to a melting temperature). DSC detects and quantifies endothermic (e.g. dissociation of carbonates, melting) and exothermic (e.g. crystallization) events occurring in the batch. Deng et al used DSC/TGA data to measure reactions in the study previously referenced in Figure 2 (Sample A). Their results are shown in Figure 5. Both DSC and TGA allow reaction temperatures to be determined, and can be used to calculate activation energies. However, they do not give direct information about the reaction chemistry. Additional methods, such as analysis of gases produced by Mass Spectrometry (MS), are used to understand the reaction byproducts. By redirecting the gases released during the DSC/TGA analysis to the MS system, the authors could assign the mass loss observed at lower temperatures to loss of water, while the mass loss from above 300ºC to approx. 700ºC is linked to CO2 release. The CO2 release shows several peaks, indicating that several reactions occurred in this temperature range. Based on batch composition, the nature of these reactions can be identified from literature, thermodynamic calculations, or complementary analyses. This example illustrates the strength of, but also the need for, the combination of several techniques for understanding the batch-to-melt conversion for a given batch.

Figure 5. Differential scanning calorimetry/thermogravimetry coupled to a mass spectrometer (DTA TGA MS) analysis of Batch A from the study by Deng et al., showing the wealth of information that can be gained by combining several techniques to characterize the batch-to-melt conversion. Reproduced from [6] with permission of Wiley. PHASE EVOLUTION

The identity and amounts of solid phases are often measured using X-ray diffraction (XRD). Most raw materials used in the batch are crystalline, and will show a strong, characteristic

pattern of peaks in XRD spectra, while glass only shows a broad, diffuse hump (characteristic of amorphous materials). The progressive disappearance of crystalline peaks therefore indicates the progressive reaction of the raw materials and their transformation into a glass melt. The appearance of new crystalline peaks can also reveal the precipitation of intermediate crystalline phases. The amount of liquid phase can also be determined.

Data from XRD measurements can be used to determine reaction pathways and kinetics. Measurements are often performed at room temperature, from samples that were exposed to heat treatments at different times and temperatures, quenched, and ground into fine powder for XRD analysis. An example of XRD analysis from the study by Deng et al [6] is shown in Fig. 6.

Figure 6. XRD spectra for Batches A and B described in Deng et al. Batches were heated up to the indicated temperature at 4ºC/min, then cooled down and analyzed. The spectra reveal the progressive reaction of the different crystalline raw materials (D = dolomite, Q = quartz, W = wollastonite, C = Na4Ca4(Si6O18) – an intermediate crystalline phase) in the batch to form an amorphous glass, indicated by the absence of peaks for the samples melted up to 1300°C. Reproduced from [6] with permission of Wiley.

High temperature in-situ XRD analysis is also possible, but requires more complex

equipment [10]. The in-situ instruments also have three important limitations. The first is the need for a flat sample surface to allow reflection of the x-ray beam. As a result, only fine powders can be used, and if agglomeration occurs during the reaction, the signal will be lost. Because the powders used in production are typically too coarse to use directly in the XRD instrument without grinding, the measured reaction kinetics will not be accurate, and in some cases the reaction pathway may also change. The second issue is that the amount of time needed to gather the XRD signal for analysis is very long compared to the reaction time for many reactions. The third limitation for typical laboratory instruments is a maximum temperature of 1200°C, which is well below the temperature of interest for many studies. There are a few custom-built instruments that avoid some of these limitations.

A limitation for XRD analysis in general is that only milligrams of sample are used, which makes it difficult to assure a representative and homogeneous sample, particularly if the effects of minor additives are of interest. However, even with the limitations, XRD is an extremely valuable tool for studying reaction behavior. The use of in-situ High Temperature Neutron Diffraction can overcome the limitation of XRD. The larger beam size and higher-intensity beam allow measurements of larger volumes of