Batch plants and cullet return systems are required for the vast majority of glass types and compositions,

starting with small installations, with a melting capacity of just 10t/d and ending with giant batch plants of up to 2400t/d (Fig. 1). These plants are capable of serving a single furnace or even several furnaces, all of which can be supplied by EME.

In terms of installed production lines and tonnage per year the container glass segment is the dominat sector in the industry. The second largest market is the flat glass sector, where typically the melting capacity of a single furnace is at least twice as big as a standard container glass factory. In past years there was a strong demand for thin and ultra-clear glass for which EME has developed special technologies to meet the special requirements for the raw material quality. The annually produced tonnage of flat glass is, however, still lower than in the container glass sector.

Fibre glass represents a growing part of the glass manufacturing industry. The main product types are glass fibres for insulation purposes and composite materials.

There are many more glass applications that require batch plants, including tableware, cosmetics, pharmaceutical, special and optical glasses. EME and its sister company Shanghai Precision serve all of these markets.

Turnkey or key componentsThe needs and expectations of each customer in order to realise their specific glass production line requirements are diverse. Some customers provide civil and

structural parts, with EME supplying the overall engineering, the key components for the raw material transport, dosing weighing and mixing, equipment for the cullet return and finally, the integral part - the control system. Other customers prefer to have a turnkey supply for a

batch plant and cullet return system. In such cases EME delivers everything above the foundations, which includes all steel works, building with infrastructure and, naturally, the technological equipment.

Everything starts with raw materials

Egbert Wenninger* gives an overview of batch plants, focusing on EME’s role and describing the two batch plant concepts available to the industry.

Batch plant

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z Fig 1. An EME batch house for an 800t/16h for container glass.

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Batch plant

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This approach reduces the number of interfaces and minimises the risk for the customer. When Sorg supplies the furnace, then joint project management is possible and it also eliminates the interface between the batch plant and the melter.

Tower vs inline conceptThere are two concepts for batch plants, both of which are common in the industry and feature certain pros and cons. Fig. 2 shows a typical arrangement of a tower batch plant. The raw material transport is mainly done using gravity and the scales and the mixer(s) are more or less directly underneath the silos.

This avoids a belt transport system, which is more challenging in terms of dust prevention. The cycle time of such a system is lower than in an inline batch plant. The footprint is also smaller, however, the buildings need to be taller and the number of raw materials can be more limited than with the inline approach. An extension at a later stage is also more difficult with tower plants. The silo plant can accommodate round or square silos that are made from steel and/or from concrete.

For medium sized glass production lines and for lines serving just one furnace a tower batch plant is a common and widely used design.

The inline concept (Fig. 3) features a series of silos along a collecting belt conveyor, which is located underneath the scales. The scales discharge on

this belt conveyor and from there the raw materials are transported into the mixer(s). Due to the transport time on the collecting conveyor, such systems are slightly slower than a tower system.

Slightly more space is required but the building height requirements are much lower. The number of raw materials is almost unlimited, and each material may have a dedicated scale or multiple materials can be weighed in a common scale. Also, various configurations of silo plants can be realised, as it doesn’t matter if they are round or square silos, steel and/or concrete or any combination of the aforementioned.

The extension of such batch plants at a later stage is simpler and less costly, since additional silos may be added and the raw materials can be added to an extended collecting belt conveyor.

This concept is mainly used for bigger batch plants serving several furnaces or where accommodating a large amount of raw materials is critical.

The key to success EME has developed, in-house and over decades, a sophisticated control system.

The standard system is based on a 100% compliant PCS7 solution. Unlike other suppliers, EME does not transfer the critical functions – the dosing and weighing – to external weighing processors, which are not integrated into the PLC and PCS7 systems.

EME can also deliver S7 systems and other controllers like Rockwell,

Mitsubishi and Schneider to meet customer specific needs. WinCC, IFix and similar HMI and SCADA systems are also part of the product range.

It is essential that any application software is fully tested prior to installation in the field.

EME has recognised this and developed its own simulation software that allows verification and validation of all features included in the software. This helps to reduce the commissioning time and mitigate the possibility of software bugs.

The system includes recipe management, a central alarming and operational logging system, as well as different statistics and reports.

EME has also developed modular redundancy, which basically allows customers to choose what level of redundancy they wish to have in their plant.

EME Maschinenfabrik Clasen was founded in 1920, and later joined the Sorg Group in 1987. The Sorg Group of companies, comprising of EME, Nikolaus Sorg and Sorg Keramik Services (SKS), supplies all the necessary equipment and technologies required for the complete batch and melting process, from the delivery of the raw materials through to the transfer of the conditioned glass to the forming process. r

*Managing Director, EME Maschinenfabrik Erkelenzwww.eme.de

z Fig 2. A schematic of a tower concept batch plant. z Fig 3. Depicting an inline concept batch plant.

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