Company in focus: Siemens VAI

A world leader in ironmaking technology: Martin Smith, manager - process engineering at Siemens VAI, provides an overview of the business...

“Siemens VAI now covers the entire portfolio of blast furnace systems for both turnkey and one-off plants, meeting the highest demands for performance, reliability, cost effectiveness, and environmental protection.”

Siemens VAI now covers the entire portfolio of blast furnace systems meeting the highest demands for performance, reliability, cost effectiveness and environmental protection. With our state of the art designs, we can offer stable and transparent processes, fast and optimal start-up, as well as consistently high levels of product quality.

We've given our competitive thrust a further significant boost by combining an array of automation and technological tools for process optimization. In our technological solutions packages we combine very different functions like predicting the iron temperature, calculating the service life of the furnace lining or optimizing stove performance.

Automation coupled with process optimization from a single source – that's the link-up our global customers know and trust. Starting with the extension to the furnace campaign, on to increasing process stability and right up to reducing total energy consumption, we apply solutions to key competitive factors. This is how we modernise older plants in order to make them competitive with modern furnace practices.

These solutions, in combination with expert project management and dedication to excellence, ensures fast project completion and rapid start-up. Our world-wide presence and comprehensive after-sales network mean immediate response should assistance be required. Our customer commitment does not end with the successful completion of a project, but extends over the entire life cycle of a plant.

Setting the standards in technology

Tailor-made solutions

Siemens VAI are dedicated to excellence in the field of blast furnace technology. Our experience, capability and resources allow us to undertake any size of blast furnace project. Tailor-made solutions are provided to meet the exact needs of any producer.

These solutions incorporate the latest process, mechanical and automation developments to enable our customers to produce the highest-quality hot metal, at the lowest possible production costs.

Consistent and Reliable Ironmaking

The overall result is consistent, reliable and low-cost hot metal production as is proven in scores of operating plants throughout the world. 

• Total blast furnace supply and services
• Proven engineering for all equipment
• Fast and reliable start-up
• Consistent production of high-quality iron
• High productivity and fuel efficiency
• World-class availability
• Ultra-long campaigns of over 20 years

Rebuilds, relines and modernisations

Siemens VAI is renowned for its ability to perform blast furnace rebuilds, relines and modernisations within extremely tight time frames. Modular blast furnace construction concepts have been perfected to minimise project duration and plant downtime for both furnace rebuilds and relines.

Unique and radical approaches have been executed, including customer partnerships, to jointly execute projects with Siemens VAI providing the blast furnace technical expertise. Where previous Siemens VAI designs are utilised, existing furnaces can be demolished, the new furnace manufactured, delivered, built and commissioned in less than 12 months.

Innovative techniques in project management and construction are utilised to minimise interfaces at each stage of the project.  In addition, certain areas of plant can be integrated into the control system prior to the furnace being taken off-line for the main repair period.

Replacement of the furnace within the existing tower structure, or the complete furnace and existing tower structure are both possible depending upon budget and time constraints. Both options allow an increase in the working volume of the furnace and hence operating capacity.

Safe, reliable and environmentally friendly

Careful planning and design

Whether for single or four taphole arrangements favoured for new large blast furnaces, the entire cast house is always designed for safe, reliable and environmentally friendly operations.

Layouts provide easy access and are based upon individual site logistics as well as furnace size. Runner design ensures efficient iron-slag separation for high quality iron, which can be collected in torpedo or open top ladle cars.

Hot metal, slag treatment and weighing facilities along with level measurement on ladles can be provided, improving tapping accuracy and furnace control.

Siemens VAI’s all hydraulic taphole opener and plugging machine designs provide the versatility of location on either side or one side of the iron trough. This permits access over the total trough length for operators, mobile equipment and for taphole dedusting.

Recent developments in slag handling have further influenced casthouse design. The use of slag ladles, dry pits, or slag granulation each make a unique contribution to the layout.

Safe, durable, modern & economical

The choice of the right refractories and cooling systems at each zone of the blast furnace is critical for successful, economic and above all safe ironmaking operations. The blast furnace hearth refractories normally determine the campaign life of a furnace. Correct material selection, specification, inspection and installation are critical to a safe, trouble-free hearth lifetime. All furnace refractories are fully inspected to ISO standards and critical items like hearth carbons and tuyere surrounds are trial assembled.

Everlasting linings

Together with the refractory lining, the blast furnace cooling system is critical to ensuring an ultra-long campaign life. Using our extensive experience and knowledge of blast furnace systems, our furnace cooling circuits feature advanced control systems, accurate leak detection and emergency back-up systems.

For the main body of the furnace, stave cooling or if required, plate cooling options can be supplied. In order to provide the optimum solution, the latest furnace cooling designs utilise both copper and cast iron staves. The use of staves reduces the requirement for a large quantity of refractory to be utilised in the furnace stack.

Flexibility for low investment

Raw material handling systems prior to the stockhouse including, ship unloading through to stacking and reclaiming, then on to feeding the stockhouse bin tops by either tripper conveyors or rotating radial conveyors.

With the use of accurate weighing systems and the ability to provide exact size fractions to the charging system, an ideal blast furnace burden can be produced. Stockhouses for ferrous, coke and additive feeds, are designed to be fully flexible, at the lowest possible investment cost.

Accurate raw material charging and burden distribution is essential for smooth furnace operation. The latest top charging equipment, supplied for both new and existing furnaces is designed for high top-pressure operation and exact burden distribution over the complete stockline.

Long life, high efficiency & reliability

Complete hot blast systems, featuring state-of-the-art design of stoves, refractories and water-cooled valves, are supplied by Siemens VAI. Both internal and external combustion chamber stoves are offered. Both types feature a high efficiency ceramic burner, maintaining low CO, SO2 and NOX emissions.

The modern Siemens VAI internal combustion chamber hot blast stove is an economical alternative to the more complex external combustion chamber design. Siemens VAI has further developed its Krupp Koppers technology to be the state-of-the-art external combustion chamber hot blast stove. Particularly suitable for ultra-high temperature operation at high blast volumes, these stoves can withstand a maximum dome temperature of 1550 °C whilst providing hot blast temperatures up to 1350 °C.

“The choice of the right refractories and cooling systems at each zone of the blast furnace is critical for successful, economic and above all safe ironmaking operations.”

Initial dewatering takes place on the hydraulically driven screw conveyor. Dewatering continues at the rotating drum filters. Final dewatering takes place either in dedicated silos or at a stockpile. Moisture content is reduced to below 12% after only two hours storage. Final product quality is affected by granulation water quantity, temperature and pressure. Granulation plants provided by Siemens VAI are designed to deliver cement quality product. The granulating head can be either a fixed design or variable orifice to give a constant water: slag ratio. Both will produce a cement quality granulate.

Recirculating water is cleaned of fine solids and slag wool by the Mesh Roll Filter. By extracting the fine slag material separately from the primary granulate, the process can operate unhindered by filter blockage which is not the case for processes extracting both size fractions simultaneously. This gives the Siemens VAI system a great advantage in terms of availability and maintenance requirements.

Pumped-type or screw conveyor/mesh roll filter arrangements; fixed or variable orifice sprayboxes; part condensed, fully condensed or open discharge; silo or stockpile storage. Whatever the requirements or contraints of the plant - Siemens VAI can provide the optimum slag granulation solution.

Siemens and NES

Siemens VAI has plans to expand its process team by approximately 25% by the end of the first quarter of 2008. There have been a number of successful recruitment drives during 2007 and an NES offer in the pipeline continues the trend.
Close collaboration with NES, working to address hiring requirements, has enabled Siemens VAI to recruit the necessary engineering personnel. An investment in time from both sides of this partnership has been a key factor in addressing the needs of the company. Meeting regularly to discuss ongoing developments and likely future requirements means that NES recruitment consultants have been able to identify suitably qualified personnel and gain a comprehensive understanding of their employment needs prior to vacancies arising.

This not only means a saving on the time and money invested on advertising and the early stages of the recruitment and selection process; it is also illustrative of the commitment that reputable recruitment agencies such as NES have for meeting the requirements of the companies they support.

Continued investment in the relationship between Siemens and NES will ensure that suitably qualified candidates are matched with vacancies when they arise. The partnership is expected to contribute significantly to future recruitment drives. 

“Siemens VAI has plans to expand its process team by approximately 25% by the end of the first quarter of 2008.”