glass international - environmental issue - september 2015

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BONUS DIGITAL EDITIONSEPTEMBER 2015

COMPLIMENTARYENVIRONMENTAL ISSUE A SELECTION OF ENVIRONMENTAL-BASED ARTICLES INSIDE

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Editor’s comment/contents

Glass International September Digital 2015

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Contents

There are now countless opportunities to recycle waste whether it be at home, in the offi ce or at your glass

manufacturing plant. It has become a prominent part of our

lives in the past few years and it is now commonplace to see recycling bins next to ‘regular’ waste bins in shopping cen-tres or in other outside public spaces.

It makes sense: recycling provides tremendous energy savings by re-us-ing items rather than remanufacturing new ones. The more items that can be recycled, the more total greenhouse gas emissions can be reduced.

The glass manufacturing industry has led the way when it comes to recycling and environmental issues. New technol-

ogy has helped cut emissions during the manufacturing process, while the recy-cling of cullet has been a long tradition at plenty of glass plants.

To celebrate this fact and to coincide with National Glass Recycling month in September, we have produced this taster supplement with a selection of recycling and environmental features from the past year. This issue has been published in a digital-only format rather than a printed version, which we hope is con-sidered a more environmentally friendly way of publishing. �

Greg [email protected]

Greg Morris

Environment: a common talking point today


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1 Contents/Editor’s comment

2 FERVER: Europe’s glass recyclers

5 Energy effi ciency in India

7 Glass decarbonisation to 2050

9 Glass recycling in Mexico

12 Rescuing Holland’s waste sheet glass 15 Reducing furnace energy consumption at Vidrala

18 Regenerator system at Pavisa

contents and comment.indd 1 9/30/15 10:30 AM

Environment


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What does FERVER do? What is the Federation’s mission? FERVER is a European Federation with a dual role: To promote the activities and protect the interests of its members; and inform its members of the evolution of European legislation and the economic climate.

The Federation aims to bring together European glass recyclers. Its object is to represent the profession (particularly towards the European institutions). Some of the activities that the association may undertake in order to achieve its objectives are as follows:

r Promotion, on a sustainable

basis, of dialogue with European Union institutions and European organisations linked to glass recycling.

r Intensify cooperation between European glass recyclers.

r Dissemination of information relating to glass recycling

r The social object is the study, protection and promotion of the professional interests of the members.

r FERVER may not undertake any commercial activity.

Can you give a brief history of the company?FERVER started in Paris in the early

nineties as an informal group of glass recyclers from Belgium, France, Italy, Spain and The Netherlands.

The fi rst offi cial Bylaws were published in 2004. Since then, FERVER has had a seat in Brussels, and a Secretary General. FERVER celebrated its offi cial 10th anniversary with a workshop in Brussels at the end of 2014. In 2012, the offi ces of FERVER moved, remaining still in Brussels, to the building of the Belgian waste management federation FEBEM, which ensures the administrative and logistic services.

FERVER:Europe’s glass recyclers

FERVER is the European association that aims to bring together European glass recyclers into a collective body. It represents the profession at an EU level. Its members are responsible for recycling 70% of all container glass in Europe.

Continued>>

FERVER 2.indd 1 9/29/15 4:17 PM


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FERVER:Europe’s glass recyclers

How is FERVER structured in terms of staff and members?FERVER is a federation of private and independent (not owned by glass manufacturers) recycling companies. The Board of FERVER is composed of the President, the Vice-President and the Chairman of the Steering Committee.

The steering committee meets at least four times a year to manage the activities of FERVER. All members are welcome on this committee if they are able to assist on a regular basis. The General Assembly takes place in June in the country of one of its members, whilst the plenary meeting meets at the end of November

in Brussels. External speakers are invited to these assemblies.

FERVER has 34 members, each recycling a signifi cant part of their glass collection into the glass industry on a long-term basis.

Are your members present throughout the whole of Eu-rope?FERVER has members in 14 countries of the European Union, and also has a member in Norway and Ukraine. Some countries are represented by one company, other countries by several members.

What does FERVER do for its members? One of the fi rst tasks of FERVER was to write an ethical code of good practices. This code, signed by all the members, is a guarantee of ethical behaviour, and of respect for the environment and the legislation for the members and their relations.

FERVER brings the members into contact to develop common positions at a European level. FERVER played a crucial role in the writing of the End of Waste (EOW) Regulation for glass cullet. Thanks

to the expertise of its representatives, this Regulation is until now the only one which has been adopted without any diffi culty by Europe. Now that the Regulation has been published, FERVER has taken several initiatives at European as well as at national levels to ensure the certifi cation process of such EOW Cullet.

FERVER also initiates studies and campaigns to develop, for example, common sampling procedures and to control the chemical quality and stability of recycled glass.

FERVER is also in permanent contact with the federations of the glass industry, FEVE for container glass, and Glass for

Europe for fl at glass, in order to create a relationship of mutual confi dence, to defi ne and even anticipate their demands in order to allow its members to offer the right quantities and qualities of furnace ready cullet.

How does FERVER encourage or promote glass collection and recycling?FERVER contacts the European institutions to stress the importance of high value glass recycling, instead of so-called down-cycling. Glass, as a material, is perfectly, totally and for ever recyclable. Once glass is used for other purposes, such as in the construction sector (foundation of roads & buildings, etc.), the circle of recycling is broken and so the circular economy stops. FERVER works towards continuing improvement of the European legislation in order to have clear defi nitions, targets and rules

resulting in an effi cient collection and an effective recycling of glass waste.

FERVER also makes contact with the take-back schemes to promote the selective collection of glass, which is the fi rst condition for high quality recycling . The focus is often put on the quantity, but it is even important to ensure the quality of collected glass. In the building sector, for example, it is crucial to collect windows on deconstruction sites in clean containers, as once glass is mixed with stones and concrete, it is not recyclable anymore.

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In the automotive sector, the European legislation on ‘End of Life’ vehicles is unclear, and leaves the field open for down-cycling.

What types of glass do your members collect and recycle?FERVER members are recycling all types of glass, provided that they can really be recycled into glass products. That covers container glass, flat glass, automotive glass, photovoltaic glass, foam glass, and fibre glass.

Due to the European legislation on extended producer responsibility for packaging and packaging waste, the higher volume of collected glass is clearly represented by container glass. There is a high demand from the glass industry to use recycled glass instead of virgin material. How much glass do members of

FERVER recycle each year? We consider that FERVER members recycle roughly 70% of the container glass put on the European market. This represents about 7 million tons of glass each year. Data on flat glass is not available at a European level, since that is not covered by directives comparable with the packaging and packaging waste Directive. FERVER has started to collect its own statistics, in order to monitor the undoubted increase in recycling of building and automotive glass over the coming years.

Do you have any targets in place to increase this rate of

recycling?As FERVER (and its members) do not hold the reins of power, it cannot fix targets. But, FERVER works together with partner federations (FEVE, Glass for Europe, FEAD, etc.) to develop KPI’s based on available statistics. The upcoming new circular economy package of the European Commission will give a boost to recycling in Europe, certainly for container glass. FERVER will also take additional initiatives in the B2B sector to increase the collection and recycling rate of flat glass in the building and automotive sector. r

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India is the fourth largest consumer of primary energy in the world. Primary commercial energy consumption in

the country for 2011/12 was around 314 million tonnes of oil equivalent (MtoE).

The industrial sector is the largest user of commercial energy in India, accounting for about 47% of the country’s total commercial energy use during 2011-12. Industrial fuel use (including non-energy uses) grew from 49.2 MtoE in 1985/86 to 146.72 MtoE in 2011/12. Despite the energy-intensive nature of the sector, industry has seen greater energy efficiency improvements since the late 1980s than any other sector in India. Industry plays an important role in the Indian economy, and has been a consistent driver of GDP growth accounting for about 27% of GDP over the last few years. The industrial sector in India is highly diversified and

comprises a range of sub-sectors and industries with immense variation in size and scale of operation, product mix and energy consumption. The industrial energy demand in the country is shared by large industries as well as Micro, Small and Medium Enterprises (MSMEs).

Important sub-sectorGlass manufacturing is one of the important industrial sub-sectors. It is a well-established manufacturing sector in the country. During 2011-12 the Indian glass market was worth about $2.7 billion. The Indian glass industry represents one of the largest markets and manufacturing capacity for glass products in the Asian region. The National Informatics Centre (NIC) has categorised the glass sector into seven segments depending upon the type of glass. The production of various

Indian glass industry: Energy efficiency opportunities

Sachin Kumar*, Ananda Mohan Ghosh and Girish Sethi outline the glass manufacturing industry’s energy consumption in India and suggest ways in which it can reduce emissions.

Continued>>

types of glass during the last few years in the country is in Table 1.

Per capita glass consumption in India is quite low (about 1.2kg) compared to other countries such as the USA (30-35kg). Although the glass industry is facing competition from alternative mediums, its key properties such as inertness, transparency and recyclability means glass will be a dominant packaging medium. Glass is 100% recyclable and therefore over a life-cycle aspect of a material it is certainly more sustainable compared to other packaging materials presently being used, especially in the food industry. Also, the increased demand from the automobile sector and new architectural aspects are creating a market for the glass sector.

Cost driverThe glass industry is energy intensive and energy consumption is a major cost driver. Melting and refining are the most energy-intensive portions of the glassmaking process and account for more than 60% of the total energy used in the glass industry. Substantial progress

Production

Type of glass Unit 2011-12 2012-13 2013-14

Glass sheet Thousand Sq. m 1,06,144 1,10,992 1,27,582

Toughened Glass Sq.m 26,78,263 35,66,399 31,91,187

Fibre Glass Tonne 42,670 42,516 38,265

Glass Bottles Tonne 12,71,920 12,46,501 9,95,10

zTable 1. Production of various types of glass in India. Source: DIPP 2012-13 and DIPP 2013-14.

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India energy efficiency.indd 1 9/29/15 4:51 PM

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has been made with energy efficiency in recent years and some processes (e.g. large regenerative furnaces) have adopted best glass manufacturing technologies that have helped in reducing energy consumption. A modern regenerative container furnace will have an overall thermal efficiency of around 50% with waste gas losses of around 30% and structural losses making up the vast majority of the remainder.

Like many industrial sectors, especially under MSMEs, glass manufacturing is one of the sectors for which specific information and data about energy consumption, key operational and technological parameters is not readily available. Apart from a few large glass manufacturing units by major players such as HNG, Saint-Gobain, Asahi Glass, Piramal Glass, Gujarat Guardian and La Opala, a substantial number of glass manufacturing units come under the MSME category. The units in the MSME category are generally located in clusters. Firozabad is an important glass-manufacturing cluster in the country.

There is a large agglomeration of small-scale units engaged in the manufacture of bangles, hollow wares, decorative items, glass beads and headlight covers. Tank furnace and closed & open pot furnace are the major glass melting technologies used in the cluster.

There are other auxiliary furnaces such as muffle furnace and reheating furnace involved in the glass processing chain. The total energy consumption of the cluster is about 0.19 MToE per year.

Furnace oil and natural gas are major fuels used by the Indian glass industry and thermal energy consumption accounts for about 80% of total energy consumption. The preliminary

estimates indicate that the annual energy consumption by the Indian glass industry is about 1 MToE. The increased cost of conventional fuels, besides environmental consideration for conservation of non-renewable fossil fuels, has encouraged glass manufacturers to reduce their energy consumption.

Waste heat recoveryThe high temperature of a glass-melting furnace (1300 – 15400°C) results in emissions of exhaust gases. This provides ‘waste heat recovery’ as one potential option to reduce energy consumption in glass manufacturing. In the glass industry, waste heat recovery potential generally depends upon the furnace size, which varies for different segments of the glass industry. Flat glass and container glass melting is performed in large furnaces, while average capacities for pressed/blown glass, insulation fibre glass and, textile fibre glass are much smaller. As can be noted from Fig 1, the smaller-capacity furnaces typically have a higher percentage of waste heat losses.

A substantial portion of the sensible heat of exhaust gases can be used to pre-heat the combustion air. Combustion air preheat can increase the furnace efficiency by up to 50%.

Regenerators and recuperators are the most frequently used waste heat recovery systems in the glass industry. TERI, the Energy and Resources Institute (India), had successfully demonstrated waste heat recovery option in small – scale glass industries in the Firozabad cluster.

This counter-flow WHR system comprises a metallic recuperator with five modules made of stainless steel. It is used to pre-heat combustion air to about 550 – 6000°C, resulting in an energy saving of

about 25-30%. In addition to combustion air

preheating, methods for waste heat recovery in glass manufacturing include preheating batch and cullet material and using waste heat boilers (WHB) for electricity generation. Generally, batch preheating is more difficult than cullet preheating, as clumping of incoming materials can affect the product quality and melting efficiency. Theoretically, any system with over 50% cullet in the batch can install preheaters.

Energy saving of cullet preheaters is estimated to be around 12-20% depending upon the cullet share and pre-heating temperature. WHB installation for electricity generation in India is not common: Saint-Gobain was the first float glass company in India to commission the WHB system to use sensible heat of flue gases to generate 1.23MW of electricity at the rated furnace pull.

The time has now come for glass plants to improve their energy consumption and environmental aspect as well. For India to be a leading player in glass manufacturing it needs to adopt various energy and environmental improvement measures for its sustainability. r

References:1. Department of Industrial Policy and

Promotion, Annual Report 2012- 13

2. Department of Industrial Policy and

Promotion, Annual Report 2013- 14

3. European Commission, Best Available

Techniques (BAT) Reference Document for the

Manufacture of Glass, JRC Reference Report, 2013

4. Economic Survey 2013-14

5. Sachin Kumar, Glass Manufacturing: Path

for Sustainable Development, Kanch, Vol 2, No.

2, Jul – Sep 2014

6. TERI Energy Data Directory and Yearbook

(TEDDY), 2013-14

7. TERI, Report on Improving Energy Efficiency

in the Firozabad Glass Industry Cluster, 2012

8. U.S. Department of Energy (USDE), Energy

and Environmental Profile of the U.S. Glass

Industry, April 2002

9. U.S. Department of Energy (USDE), Waste

Heat Recovery: Technology and opportunities in

U.S. Industry, March 2008

10. http://cdm.unfccc.int /filestorage/5/T/B/5TB

S U C 6 P K Z R G N Y J 1 X 3 4 M 8 0 9 E H A Q 2 L F / P D D .

p d f ? t = O F h 8 b m p j M X N l f D D q G I G c W o 0 e

YC5idLFUuy2q as assessed on 15 December 2014

* Corresponding Author & Fellow, Industrial Energy Efficiency Division, The Energy and Resources Institute (TERI)www.teriin.org

Fig 1. Relationship between typical furnace size and average waste heat losses in different segment of

glass industry. (Source: USDE (2002)).

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India energy efficiency.indd 2 9/29/15 4:51 PM

We all use glass every day. It is used to make an astonishing variety of products from

ketchup bottles and car windscreens to reflective paint and toothpaste. Many glass products actually help to protect the environment and reduce pollution. Fibre glass is integral to wind turbines and light weight vehicle parts which reduce fuel use.

Glass bottles and jars preserve food for longer, reducing waste. Windows are now so energy efficient that when installed in a building, they will save more energy in less than a year than was required to manufacture the glass.

These are some of the reasons why British Glass welcomes the publication of the Glass Decarbonisation and Energy Efficiency Roadmap to 2050 launched by the UK government in March 2015.

This collaborative study is a positive first step towards identifying ways to reduce the environmental impact of UK industries without compromising economic competitiveness.

A lot of work is required to make this approach a reality and we look forward to continuing to work with government and other stakeholders to build the path ahead.

CollaborationA number of stakeholders worked

together in 2014 and 2015 to help produce this government commissioned roadmap - the Department of Business, Innovation and Skills (BIS), the Department of Energy and Climate Change (DECC), their consultants (Parsons Brinckerhoff and DNV GL), British Glass (trade association), glass manufacturing companies, the supply chain, academics and others. British Glass and its members have supported this process in many ways including providing data, technical expertise and practical advice.

Involving all the key stakeholders has been a successful move. The high level of engagement has resulted in the development of a more balanced view of the situation and more practical insights and recommendations being identified for government.

For the glass sector, it has created greater levels of understanding and interest, has enabled glass companies to bring their expertise into this study and has allowed them to be involved in shaping their own future.

Options and challengesKey options identified for glass to achieve this include:

r Currently Available Technologies, e.g. waste heat recovery, generating renewable energy on site;

r Technologies which require

research, development and demons-tration, e.g. batch pelletisation, new furnace designs;

r Options which require collaboration with stakeholders outside the glass sector, e.g. using more recycled glass, substituting natural gas with biogas.

The study identifies that there are barriers to implementing these measures, which include:

Lack of financial viabilityDecarbonisation is extremely expensive and there is little customer demand for low carbon products. Any company that attempts to implement many of these options is likely to become bankrupt in months. This is because the large costs of equipment, etc., cannot be passed on to customers as customers are not willing to pay extra for low carbon glass products. Mass manufactured glass does not carry large profit margins but does operate in a global market. If UK glass companies face additional costs, then they will be less able to compete on price with foreign-made goods and this increases the risk that they will simply move abroad or close permanently.

Glass decarbonisation and energy efficiency roadmap to 2050The British Government has published the ‘Glass Decarbonisation and Energy Efficiency Roadmap to 2050’, designed to identify ways of reducing the environmental impact of UK industries without compromising economic competitiveness. Here, Valli Murphy, Environmental Policy Adviser at British Glass explains some of the finer details.

Environment


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british glass.indd 1 9/30/15 3:18 PM

Environment

Small sphere of controlOptions such as using more recycled glass are not fully within the control of the glass sector. Many other players including recycling companies, government and the general public must be persuaded to change their behaviour and recycle more glass in the UK so that it is available for glass makers to use.

Technical challengesThe report shows that to achieve high levels of CO2 reduction, existing technologies must be further developed and new step change technologies invented. This can only happen if large efforts and funds are expended on research, development and demonstration.

Valli Murthy, Environmental Policy Advisor, said: “As with all studies, there are limitations. When reading the report, we must bear in mind that factories have been considered in isolation to the world in which they operate. E.g. the significant amount of emissions saved by glass products such as energy efficient windows, or wind turbines, are mentioned, but not included in the modelling.

“Except for the ‘business as usual’

pathway, it has been assumed that it is theoretically possible to implement all the options – in reality, the amount of space available on site, technical issues, market requirements and financial viability will decide what is possible.

The modelled emissions reductions depend heavily on decarbonisation of the UK electricity grid. Without this, some options, such as electric melting, would actually increase emissions. Costs are always difficult to estimate reliably, especially as some of the technologies have not even been invented. This area needs further work before it can be used by government to inform policy decisions.”

Next stepsIt appears that there is a fork in the road ahead for the UK government and its industry, with one path being punitive and leading to increasingly unsustainable costs for UK manufacturers.

If this path is chosen, it is likely that smaller sites will close permanently and larger manufacturing companies will continue their exodus out of the UK. Not only is this bad for the UK economy and

UK jobs, sadly, it is also worse for the environment because the demand for glass products will be met by importing from longer distances and from factories in other countries potentially not operating to the high environmental standards used in the UK.

The other path is brighter - a balanced and supportive approach is adopted where industry, government and others work together to find solutions that will both improve the environment and also make economic sense. Using more recycled glass is a good example of this because it reduces energy costs for glassmakers while also reducing CO2 emissions.

Valli Murthy noted: “Decarbonisation is important and it has to be implemented in a sustainable way. If well-intentioned environmental protection sentiments are implemented unwisely, e.g. by forcing unsustainable costs onto industry, then they will do more harm than good. A win-win path must be the answer.” r

Environmental Policy Adviser at British Glass, Sheffield, UK.www.britglass.org.uk

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Vitro is a Mexican glass manufacturer with more than 100 years experience.

Founded in 1909 in the city of Monterrey, Mexico, Vitro has subsidiaries across the Americas and offers products and services to meet the needs of two businesses: Glass containers and flat glass.

The Vitro companies produce, process, distribute and market glass articles that are part of the daily life of thousands of people.

Vitro offers solutions for the food, beverage, wine, liquor, beer, cosmetic and pharmaceutical markets, as well as architectural and automotive. The company is also a supplier of raw material, machinery and equipment for industrial use.

Sustainability modelAs a socially responsible organisation, Vitro works on several initiatives aligned to its Sustainability Model. The company aims to create a positive influence in the economic, social and environmental aspects relevant to its stakeholders, in a responsible corporate management framework. Vitro contributes towards sustainable development as glass is 100% recyclable and can be fully reintegrated to its own industrial process.

The company is committed to continuing its flat and container glass recycling programmes, which represent the most important logistical effort of its kind in Mexico. Since these products do not share the same chemical composition, they must be collected and


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Glass recycling in MexicoItzel Villareal Maldonado* outlines Vitro’s sustainability strategy and how the Mexican manufacturer is leading the way with recycling in the country.

Glass recycling

sorted by type and colour.“In 2013 we recycled 91,680 tons of

glass containers, approximately 229 million pieces. This figure represents savings of 116,413 gigajoules, enough energy to light a fluorescent bulb for more than 186,923 years,” said José María Castellanos Arriaga, Recycling Manager at Vitro.

Vitro understands that recycling is an activity that requires the active participation of different stakeholders, therefore it has strengthened and created recycling alliances with educational institutions, hospitals, non-profit organisations, customers, municipalities and commercial establishments.

The company implements its container glass recycling campaigns with these groups through the programme ‘Embracing a More Transparent World’.

Vitro’s collection centres recover and reprocess glass containers, thus enabling the company to take responsibility for its products and contribute to the welfare of communities by generating direct economic benefits to the participating groups and fostering a culture of conservation and environmental friendliness.

z Fig1. Levels of glass recycled by Vitro in Mexico.

200

150

100

500

Flat glassContainersTotal

109.022126,535 119,604

152,133

181,438192,506 191,373 182,552

91,680

90,872

112,334 113,128

80,172 78,60965,590 61,330

90,008112,334

60,945 58,27462,125 80,172

65,190

43,832

2007 2008 2009 2010 2011 2012 20132006

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Glass recycling


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z Vitro operates a number of recyling schemes throughout Mexico and, thanks to its help, the amount of glass recycled in the country has steadily increased.

Continued>>

“Through this programme, Vitro has benefited more than 18,000 students, 66 non-profit organisations, five health institutions and 27 municipalities with more than two million inhabitants,” explained Castellanos Arriaga.

In 2011, ‘Embracing a More Transparent World’ was recognised as one of the Best Practices in Corporate Social Responsibility by the Centro Mexicano para la Filantropía (Cemefi) for the project’s consolidation of environmental and social benefits.

The recycling programme is divided into four geographical regions, each one with a recycling centre established and managed by a promoter. Recycling trends differ among these regions, according to their economic activities and particularities.

Western regionThis region includes the states of Aguascalientes, Baja California Sur, Colima, Jalisco, Nayarit, Sonora, Sinaloa and Zacatecas.

The state with the greatest tonnage collection in this area is Jalisco as a consequence of the presence of the recycling plant located in Guadalajara, and due to the promotion of glass recycling in industries such as tequila.

The western area collects glass from areas such as schools, neighborhoods, municipalities, bars, restaurants, hotels, bottling companies, and recyclers, who are the main allies. As a result of their constant participation, the recorded volume of collected glass bottles has remained stable over the last three years.

“Our work as promoters is to establish a constant communication with suppliers and constantly search for new organisations interested in contributing

to glass recycling,” stated Carlos Saldaña Romero, Recycling Promoter in the western region.

The trends in the region show there is an increased desire from municipalities to recycle. It is clear that society is demanding it, stimulating cooperation between the private sector and authorities.

Within Vitro’s recycling strategy, the company provides society with information related to the characteristics and benefits of glass, for purposes of promoting its properties.

“We develop action plans to promote recycling in the area and increase the amount of retrieved glass. As a company that aims for the sustainable development of its communities, we will continue to focus our efforts on consolidating a glass recycling culture and involving more participants in the western area of Mexico,” concluded Saldaña Romero.

South-central region“We, the glass recycling promoters, have the privilege of increasing recycling through the development of suppliers and by actively participating in the creation and application of new programmes in each one of Mexico’s different geographical zones,” explained Rubén Velázquez Melo, Recycling Promoter in the south-central region.

The south-central zone concentrates the activities of 12 states of Mexico, including Distrito Federal, Estado de México, Puebla, Tlaxcala, Veracruz, Morelos, Oaxaca, Chiapas, Quintana Roo, Yucatan, Campeche and Tabasco.

The ‘Embracing a More Transparent World’ programme began collecting cullet in the region in 2005, in partnership with educational institutions from Distrito Federal and Estado de México. The

number of participants has expanded each year to today’s total of 168 suppliers.

As well as support from schools, businesses, government agencies, civil and private organisations, there are now more hotels, bars and restaurants identified. As a result of ensuring that empty containers are recycled, Vitro has helped to prevent the distribution of tampered drinks which jeopardise the health of consumers.

In 2009, Vitro and Fundación de Investigaciones Sociales, A.C. (FISAC) joined forces to tackle these matters as well as promote responsible consumption.

“We will continue working with the authorities and the community to succeed in the areas of opportunity. Our goal is to spread the recycling culture in all of our daily activities, to deliver a more transparent world to future generations,” said Velázquez Melo.

Bajío regionOne of the main responsibilities of glass recycling promoters is to encourage the recovery of glass containers at the end of their lifespan.

This can be done through direct purchase at solid waste disposal sites and/or through recovery projects with customers, authorities and civil society organisations.

The Bajío region includes the states of Guanajuato, Guerrero, Hidalgo, Michoacán, Querétaro and San Luis Potosí. Vitro began promoting the glass recycling culture in the community 34 years ago, although most of the collection was carried out through the collectors in the area.

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It wasn’t until 1992 that the first formal project with the authorities in the state of Querétaro was born. The Basic Education Service Unit was interested in promoting an environmental care culture by recycling glass in the state and promoting the benefits that it offers.

Today, collections are on the rise due to other participants in the community. Society is outstanding in its commitment to glass recycling, and the economic conditions of the region and environmental awareness have benefitted from the return of this material.

In four years the collection has almost tripled from 8,000 tons in 2009 to 22,000 tons in 2013. The vast majority of collected glass for recycling is recovered at the final disposal sites, and comes from discarded household waste.

“This leads to a problem, because some of these glass providers lack the documentation declaring them as formal taxpayers. Authorisation from the Ministry of Finance and Public Credit for first hand purchases has enabled us to buy recycled glass from them,” said Rubén Nieves Pérez, Recycling Promoter for the Bajío region.

“Our efforts are ongoing, and we will continue to seek alternatives to work jointly with the authorities so that they grant the recycling programmes the importance they deserve, as well as to convince them of the benefits to society and the environment,” concluded Nieves Pérez.

Northern regionGlass containers have been recycled by Vitro in this zone since 1993. It includes the states of Chihuahua, Durango, Coahuila, Tamaulipas, Nuevo León and parts of San Luis Potosí and Zacatecas. Compared to other regions the groups that participate in the programme are more diversified.

For example, four hospitals in Monterrey have joined with Vitro to recycle seven tons of glass containers in 2013. Neighbourhood associations have also contributed, with the participation of 1,418 households. Even though their participation is not the largest of the region, they have consistently collected glass.

“Enhancing a recycling culture in the community has not only helped us diminish the environmental impact of our products, it has given us the opportunity to innovate our approach to reach new potential recyclers and change our paradigms of who should participate and how,” said Pascual González Moreno, Recycling Promoter in the northern region.

Vitro has established partnerships with different government departments to prevent glass from domestic consumption going to landfill. In the state of Nuevo León it has a close relationship with the solid waste separation plant, Simeprode.

“Bottling companies are an active stakeholder of the programme, they have understood that being part of a value chain means sharing and embracing the responsibility of their products. Collaboration among different sectors and industries is the best way to achieve it,” concluded González Moreno.

As with the western zone, the long distances between the region’s states can increase the cost of recycling. Nevertheless, Vitro works every day to overcome this challenge, and to continue to improve glass recycling in the northern states of Mexico. r

*Sustainable Development Officer,Monterrey, Mexicowww.vitro.com

Feature

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Vitro.indd 3 9/29/15 4:52 PM

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What is the aim of Vlakglas Recycling Nederland?Our mission and aim is to collect as much sheet glass waste as possible in the Netherlands, in order to have it recycled back into the glass industry.

We support the cradle to cradle (C2C) philosophy, and therefore another aim of Vlakglas Recycling Nederland (VRN) is to ensure that 20% of our collected waste sheet glass will be used in sheet glass production. In 2013 the destination of the collected waste sheet glass was as follows:

r Sheet glass industry - 13%r Insulation products - 32%r Packaging glass industry - 55%

When was the company founded?VRN is a non- profit foundation founded in 2002.

How did the idea for VRN come about? Before VRN’s foundation, waste sheet glass

was collected in Holland – however, the collected cullet was mainly production waste (the clean glass streams).

The combination glass (a mix of all types of sheet glass) was normally dumped in landfill along with other waste. This caused high costs. The founders of VRN wanted to reduce collection and recycling costs by using our collection system.

On Table 1 you can see the total glass cullet collected over the last 10 years. We do not have exact figures for how much glass still ends up as landfill, but if you compare the total collected in 2003 and the total collected in the following years, there was a growth in the amount of glass collected for recycling.

Who were the founding members of VRN?Vlakglas Recycling Nederland was founded in 2002 by the Dutch double-glazing industry, sheet glass manufacturers, glaziers and glass trading

companies united in the GBO (Glass Branch Organisation), to meet their responsibilities as producers of sheet glass. The GBO is still involved today, as one of the board members. Our system is a voluntary system and is unique in Europe.

How is the company structured? There are currently six people employed by VRN. The most important work is the organisation and maintenance of the collection network, providing information about sheet-glass recycling and ensuring receipt of any income that is due.

Operational responsibility is in the hands of the VRN’s Managing Director, with the board having overall final responsibility. VRN now has three board members, who meet three or four times a year to discuss the progress of on-going activities and future policies with the

Vlakglas Recycling Nederland is an initiative originally launched by Dutch sheet glass manufacturers. Today, this non-profit organisation has evolved to coordinate all the activities associated with recycling and collecting waste sheet glass throughout the Netherlands. Glass International spoke to Cor Wittekoek* about the initiative, and how the company has vastly improved the rate of sheet glass recycling in Holland.

Rescuing Holland’s waste sheet glass

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Managing Director. Vlakglas Recycling Nederland is a fully

independent foundation and does not receive any funds from the government.

Are you present throughout the whole of Holland?Yes, we are. We have collection points throughout the whole of Holland to ensure the collection of sheet glass from across the country.

What type of glass do you collect for recycling? We only collect sheet glass for recycling. VRN works with three types of sheet glass: Float glass, laminated glass and combination glass.

Combination glass is a mixture of all kinds of sheet glass: Float glass; insulated glass; wired glass; silvered glass; toughened glass; horticultural glass and coated glass, among others.

How is the company funded?VRN is financed by means of a waste management levy (waste disposal fee).

This amounts to €0.50 for every m2 of insulated glass that is produced in, or imported to, the Netherlands, and every manufacturer and importer is obliged to pay the charge.

The obligation has been imposed by the Ministry of Infrastructure and Environment at VRN’s request. This measure is necessary to prevent companies using the system without actually paying anything into it.

Given the confidential nature of the information concerning production figures, the levy is collected by an independent firm of accountants. Even VRN has no access to information regarding the amounts paid by individual manufacturers.

At the moment there are around 245 companies that pay the levy to VRN. In addition, some eight foreign producers pay the fee on behalf of, and as a gesture to, their customers in the Netherlands. Each year, the accountant selects ten companies at random to carry out a check on their contributions.

If any firm refuses to pay the levy or fails to agree to an inspection, VRN will take legal action to compel such firms to cooperate.

How do you organise the collec-tion of glass for recycling?VRN has set up sheet-glass collection points at around 359 locations in the Netherlands (2014); these are situated near sheet-glass manufacturers and wholesalers, window-frame factories, municipal waste dumps and container companies, and may be used by anyone for the disposal of unwanted sheet glass, at no charge.

Such waste glass may result from the production and processing of glass, for example, or from buildings that are being renovated or demolished.

Each year VRN also hires out containers to around 400-600 companies for their own use, or for projects involving sheet

glass from renovation work, for example. These containers do not serve as collection points for the general public. Furthermore, we also have containers placed in around 179 waste parks.

Waste glass can be collected through our system in various ways:

r Ad hoc (projects): VRN can provide temporary containers for renovation or demolition projects. A rental fee for these containers is required.

r Storage and transfer stations: A company can deposit waste sheet glass at one of Vlakglas Recycling Nederland’s affiliated storage and transfer stations. A maximum handling fee of €10.00 p/ton is charged.

r Collection points: Small amounts of sheet glass can be deposited free of charge at Vlakglas Recycling Nederland’s collection points. These collection points can be found at selected glass resellers and producers, but also at a number of major waste recycling centres.

r Container rental: Companies can also hire a container for their own use on site.

Containers are replaced three working days after notification has been received that they are full. The number of containers at each location is based on the quantity of sheet glass that is brought to it. VRN works with a single national transport company, which organises the entire operation on our behalf.

Continued>>

z VRN provides collection containers for companies working at demolition sites, as well as providing free-to-use sheet glass collection points (above left and centre).

The cullet is then recycled back into the glass manufacturing process (above right), predominantly into container glass factories.

z Table 1. Collection results (tons).

Year 2013 2012 2011 2010 2009 2008 2007 2006 2005 2004 2003

Total tons collected 74.821 85.590 89.151 86.000 82.490 73.460 74.044 65.662 61.067 54.572 37.830


Glass recycling


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The choice of the transport company is based on the outcome of a tendering procedure conducted by VRN. They also supply the containers for the sheet-glass waste and ensure that no other type of waste is put in them, as this could contaminate the sheet glass.

It is important that the waste glass is clean when it is delivered to the collection points: VRN has high acceptance requirements, which the companies and collection points have to follow to ensure that the waste glass is clean.

Have you received any recog-nition for your environmental achievements? In 2013 VRN received the Lean and Green award Star from Connekt. This is an incentives programme which encourages companies to increase sustainability in their logistics, by taking measures which not only yield a saving in costs, but also reduce the environmental impact.

VRN transported about 37,600 tons of glass cullet by vessel to the recycler. This reduces the CO2 emissions and in 2013 we achieved 23% CO2 emissions reduction in comparison with 2008 when we started with this programme.

Do you work alongside any oth-er recycling agencies?VRN works in partnership with two recycling companies in Belgium, as there are no major sheet-glass recycling firms in the Netherlands. The distribution of the tonnage of sheet glass that goes to the recyclers is based on the outcome of a tendering procedure conducted by VRN.

The VRN’s haulier then uses the locations of the collection points and the recyclers as the basis for calculating which of the former can most efficiently supply which of the latter.

The recyclers are responsible for recycling the sheet glass and for selling it to the sheet-glass, hollow glass and glass wool industries. However, VRN makes every effort to ensure that as much sheet glass as possible is recycled back in to the sheet-glass industry.

Are you involved with any other projects?We are currently involved in some projects which we monitor closely. Examples of some of these projects are:

r Research into setting up collection structure in other countries: The system

that VRN has set up in the Netherlands is unique and we are willing to share our knowledge to help other countries implement this system.

r Research into the separate collection of sheet glass waste during demolition projects: We are working in anticipation of the new European legislation banning the dumping of demolition waste, which includes glass also.

r VRN and Maltha Glassrecycling cooperate with AGC Glass Europe in its Flat to Flat recycling project. This project has received a Life+ subsidy from the European Union, and aims to develop and validate an innovative method for recycling and upcycling flat glass. The expected results of this projects are: 12% CO2 reduction, 5% energy saving, and 25% reduction in the use of raw materials.

Based on figures from 2011, about 20,000 tons of waste glass is lost in the Netherlands in demolition each year. r

*Director, Vlakglas Recycling, the Netherlandswww.vlakglasrecycling.nl

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Reducing furnace energy consumption at Vidrala

Furnaces


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One of the main priorities in glass industry manufacturing is furnace efficiency. It is well known that

large cost savings can be achieved by reducing energy consumption.

Industrial experience shows that glass quality is often the constraining factor in the process of reducing energy.

Gas emissions and other pollutants, closely linked to energy management in the furnace, have to be kept under the legal limit. So decreasing specific energy consumption by keeping the standard glass quality specifications and limiting pollutants has become a challenge for glassmakers. During the economic crisis that affected southern Europe three years ago, energy became a key factor for Vidrala, so the company took on the challenge and prepared its own strategy.

The strategy was structured on four main blocks: (1) organisational changes by the integration of furnace operation and glass chemistry departments; (2) development of management and control procedures; (3) investigation of every issue in glass quality that may limit energy reduction (blisters, cords, stones); and (4) the roll-out of research & development projects.

Department integration Furnace Operation and Glass Chemistry were two separate departments within Vidrala until 2012, with their own targets and working procedures, and separate action plans in the case of problems. The Glass Chemistry department’s working procedure was based on adjusting the

colouring/reducing compounds to achieve colour specifications and/or modifying raw material proportions to keep the target oxide percentages. In the Furnace Operation department any blister or seed problems were solved by increasing energy consumption.

So the first step was to integrate Furnace Operation and Glass Chemistry into the same department, together with the environmental area. Common targets were marked, action plans put together and a strategy coordinated.

Furnace operationWorking procedures in furnace operation are generally based on experience and therefore submitted to subjective actions.

This method is valid on a day-to-day basis but the results are unpredictable and lead to an instability that results in higher energy consumption.

So an energy introduction model was developed, where all the input parameters were determined and the actions standardised.

Vidrala’s Dr. Estela Alejandro* and Diego Ochoa** outline the company’s energy efficiency strategy, which in recent years has focused on its furnaceoperations and glass chemistry departments

Continued>>

z Fig 2. Different behaviours observed in blister occurrence according to the redox index value.

70 71 72 73 74 75 76 77 78 79 80 81 82 66 67 68 69 70 71 72 73 74 75 76 77 78

Type (a)

Redox index

Blis

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/ton

gla

ss

Type (b)

% o

ver

tota

l iss

ues

100

2012 2013 2014

90

80 70

60

50 40

30

20

10

0

Fig 1. Reduction

of blister issues at

Vidrala in the 2012-

2014 period.

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This method is based on three pillars: (1) cost control, by balancing fossil and electrical energy depending on price; (2) definition of temperature and consumption targets; and (3) calculation of the energy portion directly applied to glass, taking into account the external effects. The method was standardised by corresponding working procedures and data registration forms, and implemented in every plant, as well as the formation of communication channels via reports.

Energy consumption values stabilised as a result of the energy introduction model and high consumption peaks disappeared, which resulted in average lower values.

Although the stabilisation of the process reduced energy it was still far from the targets sought by the department.

A temperature decrease was regarded as the necessary next step to achieve the required reduction targets. Internal and external benchmarking was performed to identify the best practices to achieve a temperature reduction while still retaining glass quality. Targets took into account all the boundary conditions: type of furnace, colour, cullet percentage and pull.

Best practices and defined targets, managed by the new standard energy introduction model, have led to a 2% reduction in energy consumption in two years (2012-2014).

The method became insufficient as it was constrained by the appearance of

blisters, mainly in reduced glasses, and mostly in olive green – the main colour produced by Vidrala. It was necessary to carry out research to improve energy consumption reductions.

Vidrala’s research projects continue today and these focus on process simulation by furnace and regenerator modelling, and on the optimisation of the energy introduction model with the help of commercial software.

Glass chemistryThe optimisation and control of glass redox conditions during melting and fining are critical elements to achieve a good energy consumption/glass quality ratio, usually when the furnace operation has been optimised.

Within industrial soda-lime container glasses, one the most redox sensitive colours is the so-called olive green (and its variations), that can produce, among others, colour deviations and blisters.

This is a problem since it affects quality specifications and generates production losses. The narrow redox stability region of the glass requires accurate control of many elements. These include furnace operation parameters (as described above), cullet composition and its organic content, and the proportion of colouring, reducing and oxidising compounds in the batch that ensure glass quality specifications and that minimise production losses.

To reduce energy consumption of these Continued>>

sensitive glasses without affecting quality and pull, it is essential to understand how optical and chemical glass parameters can influence during the melting and fining processes.

Blisters are the main issue affecting olive green quality and are the main obstacle to energy reduction targets. The glass chemistry department strategy had to be re-defined: first, blister issues had to be reduced. For this, it was necessary to understand how glass chemistry works on blister formation mechanisms.

Control modelA new reference glass control parameter was established in the definition of the management procedures: the ‘redox index’, expressed as Fe(II)/Fe total ratio. The redox index had always been measured but never used as a reference.

The redox index target values were defined for each colour, as well as upper and lower limits. A glass chemistry control model was then developed and built to guarantee the following:

r Colour specifications and viscosity properties, to be always between upper and lower limits;

r Redox index between upper and lower limits;

r Stone and blisters under maximum limit values; and

r The cost of the batch.

The operation is based on the corrections of deviations when parameters go over the upper and lower limits, parameterisation of the actions and, importantly, the preservation of cullet stability.

This final issue is crucial because most of the cullet used at Vidrala for olive green production is mixed cullet.

The method was standardised by corresponding working procedures and data registrations forms and then implemented in every plant. Communication channels via reports were also set-up.

The result has been an increase of the stability of the reference parameters and quality specifications.

Cullet stabilityCullet is the most important raw material used for olive green production so a method was developed to keep its stability.

r Characterise the origin of the cullet, knowing that the origin is described

% SO3 in glass

0,0370,0350,033

0,029

0,0250,0230,0210,0190,0170,0150,0130,0110,0090,007

63,0 65,0 67,0 69,0 71,0 73,0 75,0 77,0 79,0 81,0 85,083,0

0,027

0,031

SO3<0,019%

Redox index

Blis

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66 67 68 69 70 71 72 73 74 75 76 77 78 70 71 72 73 74 75 76 77 78 79 80 81

Threshold~70-71% Threshold~75%

z Fig 4. Examples of blister occurrence in type b furnaces at different redox value thresholds.

Fig 3. Sulphur

solubility vs. redox

index value for sev-

eral reduced glasses

in Vidrala. Arrows

indicate the redox

index value where

sulphur is below

0.019% in glass.


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by the following parameters: the type of cullet (mixed, flint, amber), colour proportions, grain size and organic content. This origin issue is even more critical in Vidrala’s case, where up to nine different cullet origins can be used at the same time.

r Separation of cullet in plant by origin, the different origins are never mixed, both for storage and consumption.

r Detailed planning of storage and consumption of each origin. These plans are done to reduce the number of changes, both changes in % and changes in origins. They also take into account the age of the cullet, that is to say, the organic content. This way the furnace with longer periods of stability can be provided.

r Improving quality control procedures in plant.

r Collaboration with the supplier and treatment plant.

Blister issue reductionA so-called issue investigation procedure was set-up to undertake the blister reduction project. The aim of the procedure was to identify standard behaviours that could lead to established practical working protocols. During the issue investigation, the issue cause was identified, glass and furnace data analysed, production losses calculated and corrective and preventive action plans defined. All results and conclusions were registered in the issue report.

Standard contingency protocols were created thanks to the issue investigation, both in glass and furnace operation, that have lead to a reduction of 53% of blister issues in two years (Fig. 1).

In spite of this large reduction, some blister issues still remained that were not controlled rapidly enough. Therefore, a new project was formed to analyse and understand how glass chemistry influences blister formation mechanisms in Vidrala’s furnaces.

To assess the influence of glass chemistry in blister formation, hundreds of industrial data were analysed, taken from everyday production, with the purpose of finding standard behaviours and relationships between them.

Analysed industrial data consist mainly of glass data (redox index, SO3 content, iron oxide and chromium oxide content), furnace data (energy consumption, rising temperatures) and quality data-like blister concentration. These data belonged to 10 different colour campaigns in six furnaces, mostly olive green glass, but

also amber and antique, in a two- year period (2013-2014).

When comparing the industrial data, two apparently contradictory behaviours were observed. There are some furnaces where blisters appear when glass is oxidised below a certain number of redox index (type a, Fig. 2). When the redox is higher, blisters become less. There are other furnaces that behave in exactly the opposite way; blisters appear over certain redox index, and they become less when glass is oxidised (type b, Fig. 2).

For the (a) type furnaces, the observed effect was a consequence of sulphur solubility in glass. In Fig. 3, blisters appear when the sulphur solubility is below 0.019%. In some furnaces, this limit happens even at high redox values for olive green (>77 %).

From an industrial data assessment, it was observed that, at a certain redox index value, the lower the solubility the more frequent the blister occurrence. Similarly, the larger the slope of sulphur solubility curve, the larger the risk of having blisters.

At a certain redox value, the differences in sulphur solubility depend on several factors, such as chromium oxide content, glass temperature and possibly other parameters not yet identified.

Research is underway to increase sulphur solubility in order to get more stability in a larger redox region while keeping colour specifications.

Type b furnaces behave exactly the opposite. There is no blister problem at oxidation but at reduction, that is, over certain redox values bubbles start to appear. This effect has been observed not only in olive green glass but also in other reduced colours such as amber

and antique. For these types of furnaces, there are different redox thresholds for blister occurrence; blisters appear over different redox values depending on the furnaces (Fig. 4). It is certain that this effect is not a sulphur solubility question. Some hypotheses are under research and several laboratory and industrial scale tests are planned.

ConclusionVidrala has done a lot of work in the past three years to reduce energy consumption in glass furnaces. The strategy has been defined not only in technological areas, but also in organisational and management aspects. The furnace operation and glass chemistry areas have to work interdependently and cannot leave out environmental management and furnace maintenance.

Glass companies have plenty of knowledge based on experience and with subjective opinions. Improvements in energy reduction and glass quality can be achieved only by gathering and structuring this knowledge, with clear working procedures and well-defined targets based on internal and external benchmarking.

It is important to understand the mechanisms that dominate glass melting and fining processes and to learn how the different input parameters (glass chemistry, energy sources, batch preparation) influence these processes. Data analysis and simple lab and industrial scale tests can be performed to assess the open hypotheses. r

*Physical Chemistry Laboratory Manager, **Furnace Production Manager, Vidrala, Bilbao, Spain. www.vidrala.com/en


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Improving energy efficiency and reducing operating costs of glass melting furnaces have been continuous

goals for the glass industry, especially for glass plants located in geographic regions with high priced natural gas. The conversion of air-fuel furnaces to oxy-fuel combustion is generally known to improve furnace energy efficiency and reduce natural gas consumption. However, operating costs are not always reduced unless there are savings from the avoidance of downstream emissions control, and about a quarter of the fuel energy input to the furnace is wasted as sensible heat in the flue gas.

Recovering this waste energy from the flue gas has the potential to further improve energy efficiency and substantially reduce the operating costs of oxy-fuel glass furnaces.

While several heat recovery approaches have been considered in the past, Praxair’s new Optimelt thermochemical regenerator heat recovery system is a low–cost solution to maximise the heat recovery from glass furnaces, improve energy efficiency of the furnaces, and minimise furnace emissions. The Optimelt system delivers these benefits using regenerators similar to conventional air-regenerators to combine the conventional preheating step with a chemical reforming process. In the reforming step, a mixture of natural gas and recirculated flue gas react endothermically in the hot regenerator checker pack to produce a hot syngas

stream which is combusted in the furnace with oxygen. This combined preheating and reforming process results in a net reduction of natural gas and oxygen of about 20% to 30%, compared to conventional oxy-fuel and regenerative air-fuel furnaces, respectively.

Optimelt heat recovery process In the Optimelt system, unlike conventional oxy-fuel furnaces, the flue gas is directed to a regenerator chamber where it is cooled to about 1200-1300°F (650-705°C) before exiting the regenerator. A portion of the cooled flue gas is then recycled, mixed with the natural gas and introduced at the bottom of the other regenerator (Fig 1). This mixture absorbs energy stored in the

refractory checkers. When the gas mixture is heated above a certain temperature, various endothermic chemical reactions occur at atmospheric pressure without the need for additional heterogeneous catalysts or separate steam generation. The combination of preheating and endothermic chemical reaction produces a hot syngas stream which has a higher heating value about 1.2 to 1.3 times the heating value of the natural gas fed into the bottom of the regenerator (depending on the flue gas temperature and extent of reforming achieved in the regenerator). The ability to upgrade the energy content of the natural gas fuel into higher energy-content syngas in the

Continued>>

z Fig 1. Optimelt Reforming Process in Regenerators.

Fig 3. In-furnace

animation of Optimelt

system in end-port

configuration.

Hot syngas to furnace

Endothermic reaction to syngas (CO and H2)

Preheating of mixture

Injection of natural gas into flue gas recirculation

Thermochemical regenerator system proves itself at Pavisa

Iyoha U. *, Wu K.*, Laux S.*, Kobayashi H.*, de Diego J. ** outline a regenerator system that, after evaluation at Mexican glass manufacturer Pavisa, led to 15 to 16% natural gas and oxygen savings compared to an oxy-fuel furnace.

praxair.indd 1 9/30/15 8:27 AM

Environment


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regenerator results in the fuel savings of 20% to 30% delivered by the Optimelt system. The reformed gas or ‘syngas’ leaves the regenerator at the top and is combusted with oxygen in the furnace, providing efficient combustion for the melting process.

SavingsFuel savings by the Optimelt system vary depending on glass type, furnace type and furnace size. For example, Fig 2 shows a calculation of the fuel savings for a 300 tpd container furnace with 500kW boost and 50% cullet ratio over a furnace life of 12 years. The furnace aging factors (increase in fuel consumption over time) were calculated to be 1.35, 0.54 and 0.71% per year for the air fired, oxy-fuel and Optimelt furnaces, respectively, based on a set of consistent assumptions about increases in wall heat losses, air infiltration and deterioration in regenerator performance. As shown below, the fuel savings achievable by the Optimelt system at mid-campaign are about 20% and 28% relative to the state of the art oxy-fuel and air regenerative furnaces, respectively. For larger furnaces such as flat glass furnaces, fuel savings by the Optimelt system are expected to be even higher because the total wall losses are lower per unit glass pulled, resulting in more recoverable waste energy in the flue gas.

Results from Pavisa, Mexico The Optimelt system was installed in 2014 for evaluation on a commercial 50 tpd oxy-fuel container glass furnace at Pavisa, located in Mexico. Pavisa manufactures glass and crystal products for the global wine, liquor, food, perfume, and pharmaceutical industries. The furnace has a melting area of approximately 29m2 with a single charger on the left, and six Praxair

oxy-fuel wide-flame burners in the side walls. The addition of the Optimelt heat recovery system to the furnace changed the combustion configuration from the original side-port firing with the oxy-fuel burners to end-port firing of the Optimelt syngas burners (Fig 3). The proprietary oxy-syngas burner system is designed to deliver a bright, luminous flame and can be tuned to attain the desired combustion space and glass temperature profiles in the furnace.

Fig 4 shows actual results measured on the commercial 50tpd furnace at 20% to 30% cullet ratio. The graph shows the fuel consumption for the conventional oxy-fuel furnace (blue circles) compared to the Optimelt system (red squares) for various glass pulls, as well as the theoretical model predictions for conventional oxy-fuel (solid blue line) and Optimelt (dashed red line) systems. As can be seen in the graph, Optimelt successfully reduced total fuel consumption by about 15% to 16% for the type of glass being melted, and there was agreement between the theoretical model and the actual furnace measurements. The fuel savings achieved in this installation are on the low end of potential fuel savings to be achieved from the Optimelt system because of the relatively small furnace size. For smaller furnaces, the ratio of total wall heat losses relative to the total heat input is high. As previously discussed, the potential fuel savings for larger furnaces resulting from the Optimelt system are expected to be in the order of 19% to 21%, compared to conventional oxy-fuel furnaces.

The installation at Pavisa has proved to be robust and reliable, with more than 91% availability demonstrated in the first four months of operation. Whenever the Optimelt system is not available the oxy-fuel burners in the side walls start up automatically as backup, avoiding any production interruptions. Shutdowns

to the operation of the Optimelt system experienced so far during the test were due largely to mechanical issues unrelated to the technology, such as failure of the instrument air system. Optimelt availability is expected to surpass 96% following upgrades to the mechanical equipment that resulted in system disruptions. Regenerator performance was also consistent, with respect to heat recovery and temperature profiles. Furthermore, visual inspections of the regenerators and checkers have shown no discernable signs of corrosion or deterioration of the refractory materials.

ConclusionPraxair’s Optimelt thermochemical regenerator heat recovery system is a low–cost solution to minimise furnace emissions and maximise heat recovery from glass furnaces and improve furnace energy efficiency. The system combines preheating and endothermic chemical reaction to recover waste energy from the flue gas and to produce a hot syngas stream which has a higher heating value about 1.2 to 1.3 times the heating value of the natural gas fed into the bottom of the regenerator.

This technology is currently in operation on a commercial 50 tpd container glass furnace in Mexico, where about 15% to 16% natural gas and oxygen savings was demonstrated compared to the oxy-fuel baseline furnace. Optimelt has proved to be robust and reliable, with a 91% availability demonstrated at Pavisa in the first four months of operation. For larger furnaces, Praxair expects fuel savings of about 20% to 30%, compared to conventional oxy-fuel and regenerative air-fuel furnaces, respectively. r

*Praxair, Danbury, CT, USA**Praxair, Madrid, Spain www.praxair.com

Fig 2 Example of

Fuel Savings from Op-

timelt System versus

furnace age.

Fig 4. Data Optimelt

system test on Pavisa’s

50 tpd commercial

furnace.

Fuel

sav

ings

by

OPT

IMEL

(%)

35

30

25

20

15

10

5

0

0 5

OPTIMELT vs Air RegenOPTIMELT vs Oxy-fuel

10

Furnace age (year)

15

7.5

7.0

6.5

6.0

5.5

5.0

4.5

4.0

3.5

3.0

35

Oxy model 20% cullet

TCR model 20% cullet

Oxy data 20-25% cullet

Oxy data 30% cullet

TCR data 20% cullet

40 45

glass pull (mTPD)

50 55

Fuel

con

sum

ptio

n (G

J LV

H/m

TPD

)

praxair.indd 2 9/30/15 8:27 AM

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glass international - environmental issue - september 2015

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