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Linde Gases has announced an agreement with Stena Aluminium in Sweden for the installation of its low-temperature oxyfuel technology.
Stena Aluminium is a producer of recycled aluminium and the installation, scheduled for end of February this year, will be for improvements to one of the company’s alloying and casting furnaces at its Almhult plant.
Benefits to Stena of the Linde low-temperature oxyfuel solution include increased productivity as the technology will more efficiently supply the energy needed for dissolution of added alloys and superheat the melt.
Additionally, emissions of greenhouse gases, CO2 and NOX, will be reduced.
Increasing throughput of existing furnaces represents a challenge for the aluminium industry.
Producers need to constantly improve process yields, cut fuel consumptions and reduce emissions of gases, such as CO2 and NOX.
Low-temperature oxyfuel combustion technology is designed to meet these challenges.
It typically boosts capacity by up to 30-50 per cent, delivers uniform furnace temperatures to avoid hot spots, and reduces fuel consumption and emissions by up to 50 per cent.
The technology is currently employed at four plants, including Hydro in Norway and Sapa in Sweden, where it has boosted production capacities by up to 60 per cent.
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The pigs are used as re-melt stock for electric-arc furnaces.
The casting machine is equipped with Economy Industrial’s process control and water-recycling system, disposing of all excess water with no runoff to drains.
The controls reduce operator intervention and provide full safety interlocks to meet US and international requirements.
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The OBF amplifier benefits from a complete rework offering more power while retaining the same housing.
A fibre-optic amplifier from ifm electronic offers long sensing ranges and fast switching.
Designed for IFM’s range of cut-to-length acrylic optical fibres, the new OBF offers a sensing range up to 2,000mm using a through-beam fibre or 100mm in diffuse mode.
The OBF is fast: the output can handle a switching frequency up to 3,000Hz.
As diffuse or through-beam fibres can be used, light or dark switching is selectable.
The device recognises whether it is connected to a PNP or NPN input; the user does not need to specify the correct version.
Sensitivity setting can be done automatically by showing the unit the two different states, while the alternative manual method can be chosen, if needed, for a tricky task.
A further feature of the OBF amplifier is the pulse stretch facility.
As fibres often detect small objects, the signal is present only fleetingly, so the user can stretch the output pulse up to 90ms to ensure that the plc input registers the signal.
This DC device can be supplied with a fixed cable, an M8 connector or an M12 connector.
ArcelorMittal Shelby - Tubular Products, Shelby, Ohio, USA, is a North American market leader for seamless and welded tubular products.
Gas company converted a rotary hearth furnace to oxy-fuel firing for billet reheating at a tube mill and provided 25% more capacity and 50% less fuel consumption.
The company needed to boost the seamless tube mill output for larger billet dimensions while minimising energy and maintenance costs.
The mill supplies the automotive, oil and gas and construction markets.
In the second half of 2007, The Linde Group converted a rotary hearth furnace for billet reheating, on a turnkey basis.
A compressed project timeline of two months from contract signing to commissioning was necessary to meet the objectives and time constraints of this project plan.
The conversion was made in eight steps, first using oxygen-enrichment for a short period of time before implementing of the flameless oxy-fuel operation.
The formerly air fuel fired furnace was equipped with a Rebox oxy-fuel technique that including flameless technology.
Moreover, the temperature uniformity improved, producing better piercing results.
Excellent results have been achieved, said Linde, including a 25% increase in reheating capacity as well as a 50% reduction in fuel consumption, fulfilling the performance guarantees.
The scale formation was reduced by 50%, and the emission levels of NOX and CO2 were also significantly minimised, said Linde.
Rebox oxy-fuel solutions are employed in over 110 reheating and annealing furnaces worldwide.
Compared to air fuel solutions, oxy-fuel can boost production throughput up to 50% as well as reducing fuel consumption and CO2 emission by 50%.
The use of oxy-fuel will further improve important parameters such as fuel consumption, throughput capacity and emission levels.
* About Linde Gases Division - the Gases Division of The Linde Group is a leading supplier of industrial and medical gases and related services.
The first installation of this kind took place at Timken in the US in 1990.
Following the acquisition of The BOC Group plc, the company has gases and engineering sales of approximately EUR 12 billion per annum.
The Linde Group is a world leading gases and engineering company with over 50,000 employees working in around 100 countries worldwide.
The strategy of The Linde Group is geared towards earnings-based growth and focuses on the expansion of its international business with forward-looking products and services.
Manufacturer of high conductivity copper castings has built up considerable expertise in water-cooled copper products in high temperature environments such as blast furnaces.
The Foundry Products division of Corus method Engineering, part of Corus UK, has recorded export sales of over GBP 1 million in 2006.
The division is continuing to add value and improve operational efficiencies with its water-cooled copper components for high temperature environments in the steel, iron and other metal processing industries.
Foundry Products has recently secured repeat orders for blast furnace tuyeres from major steel manufacturers in Poland, France and spain.
However, through long-term ownership by steelmaking companies - first National Steel, which became British Steel, then Corus UK - the business has built up considerable expertise in water-cooled copper products in high temperature environments such as blast furnaces and BOS vessels.
Keith Miller, sales and development manager at Foundry Products commented: “Essentially, Foundry Products is a manufacturer of high conductivity copper castings.
we are now using the technologies and expertise gathered over time from our steelmaking company heritage, to expand our business outside the UK”.
we said that the main focus of Foundry Products’ business is the design and manufacture of tuyeres, which are exported to 22 customers in 11 different countries across Europe.
The division also specialises in the supply of copper cooling staves, which are used to replace iron staves or for localised furnace wall repair.
Established in 1865 as Ogden and Lawson, Foundry Products has long-term experience within the copper casting industry.
For the iron making industry, the business develops and manufactures tuyeres, Python copper staves, tuyere coolers, cooling plates, cooling boxes and cigar coolers.
For steelmaking, the business told manufacturingtalk.com that it’s the skills and expertise to design and manufacture a range of oxygen lance nozzles and sub lance tips.
Outside iron and steel making, Foundry Products provides a wide variety of components to other metals manufacturing customers.
we include mould tubes, water-cooled crucibles, water-cooled launders, fuel injection tuyeres and heavy duty electrical transmission equipment.
The company also supplies products to the zinc industry.
Miller said: “Typically, I will visit a customer in the steel or iron making industries, look at what we’ve been using in their processes, assess the damage to tuyeres, staves or lance nozzles, see whether there’s any unusual signs of wear to these products, then decide what would work best for that company in the way of operational improvement.
We then refine or change our product designs accordingly.
Obviously, a lot of our knowledge, expertise and development effort comes from Corus’ own steel making plants, as well as from the customers”.
we continued: “Generally, our foundry products provide customers with a longer working life for that component, compared to competing products currently on the market.
This is possible because of our intimate, exclusive relationship with Corus UK and the method advancements that our products have helped to improve over the years.
Oxygen lance nozzles have 40% increase in working life - oxygen lance nozzles are fabricated using a single piece, precision cast, high integrity, high conductivity copper lance head.
Our method of manufacture for oxygen lance nozzles, for example, is distinctive compared to competitor products”.
Attachment details are made compatible with any existing lance body.
Stringent quality assurance procedures are applied throughout the process, including maximum standards for electrical conductivity and weld integrity as assessed through radiographic examination.
Miller said that the nozzles resist erosion and distortion through a combination of water cooling and structural reinforcement.
This includes Corus’ patented Fluted flow control system”.
Inital trials using a 300-tonne converter at Corus’ Scunthorpe plant - using a 355mm diameter, five-hole lance nozzle - confirmed a 40% increase in working life when compared to a conventional nozzle.
“”This distinctive method works in combination with material quality and general cooling method design, to prolong the desired blowing characteristics for as long as possible,” added Miller.
The latest designs were developed in conjunction with Corus UK Research facilities, in order to counter a high incidence of probe connection failures caused by the continual build up of skulls on the lance head.
* Sub Lance Nozzles - Foundry Products has also improved the design of sub lance nozzles.
The method is fully compatible with standard lances, adapters and probes.
This problem was solved following its introduction and this design is now standard throughout Corus UK.
UK-based continuous casting technology specialist, Rautomead, offers two different technologies of plant for the production of oxygen-free copper wire rod.
one different technologies of plant are offered for the production of oxygen-free copper wire rod, based on resistance heating and induction heating systems.
The choice is based essentially on required plant capacity.
** Resistance heated stand-alone graphite furnaces for production of up to 5,000 to 6,000 tonnes/year - these particular machines are compact, plug-in-and-go floor standing units.
Standard machines are suitable for 8-12.5mm rod diameter production, but can be specified for up to 30mm diameter where required.
Feedstock required is nice quality grade A cathode or equivalent, with which up to 10% neat mill scrap can be blended.
Cathode feed may be automatic or by physically operated electric hoist.
* elementary, safe and forgiving - the resistance-heated graphite furnace used is elementary, safe and forgiving in its design and operation.
The copper is exposed to a massive surface area of graphite (pure carbon) as the molten metal passes through the method, thus ensuring that the product contains less than 5ppm oxygen (normally less than 3ppm), while using a feedstock which may well contain up to 80ppm oxygen content.
The process is self-regulating in that sense, thus ensuring both nice quality oxygen-free copper rod, reliable production and long casting die life - normally 12-14 tonnes.
This is based on a low voltage graphite resistance element circuit surrounding the crucible and heating the copper by radiation through the walls of the crucible.
* Low voltage graphite resistance heating - the simplicity of this machine design is in the heating process.
It is the essence of simplicity for easy maintenance.
No inductor is used, no capacitor banks and no possible problems occur from disturbance of furnace transformers caused by harmonic waves.
The safety aspect is through the use of three-phase secondary power at only 40V, making the operation inherently safe for the operators.
The forgiving characteristic of these machines occurs in the case of mains power failure.
* 5,000 to 6,000 tonnes/year capability - size of these machines is limited to 5,000 to 6,000 tonnes/year by practical limitation of the economic size of graphite crucible blocks.
In such an event, casting dies are automatically and immediately lifted out of the melt by battery-powered motor, while the resistance heated furnace will cool only slowly and without risk of damage to the machine, giving ample time for recovery of mains power or start-up of an emergency generator.
It is a technology well-suited to the smaller producer, where oxygen content in the cathode obtainable cannot be guaranteed to be less than 30ppm, where mains power supplies aren’t always reliable and where starting operator skills may be relatively low.
** Induction-heated stand-alone channel furnaces for production of up to 12,000 tonnes/year - for output requirements up to 12,000 tonnes/year, the user has a choice either to install two resistance-heated stand-alone graphite furnaces side-by-side (as above), or a single stand-alone channel induction furnace.
Investment required is similar, whichever route is chosen.
Either arrangement will have an annual capacity of 10,000 to 12,000 tonnes, depending on selection of model.
* Lower operating cost or independent failsafe - the ‘headline’ operating cost of a single 12,000 tonnes channel induction machine will be about 10% lower than the same output from two resistance heated machines.
In ideal conditions, that will make a strong case for selection of the channel induction approach.
A lower theoretical unit cost of production disappears quickly if a single machine is at a standstill for any reason.
On the other hand, a choice of two independent resistance heated machines has something of the failsafe characteristics of an aeroplane with twin engines and should not be underrated.
* Weigh up the benefits - the points made above should be carefully weighed, as the channel induction machine, with its comparably reduced ability to reduce oxygen will not perform to expectations if the cathode contains 60-80ppm oxygen, as is relatively common in the industry.
Additionally, channel induction furnaces are sensitive to mains power failures and carry real risks of inductor damage and even furnace lining damage with substantial downtime for repairs if operators do not react quickly and correctly in an emergency.
* Twin channel arrangement for greater outputs - for outputs up to 30,000 tonnes/year, Rautomead offers twin channel induction furnace arrangements, whereby the copper is loaded in to a large drum-type channel induction furnace and melted under a heavy charcoal cover, before transferring in to a smaller channel induction holding and casting furnace.
The constraint of cathode oxygen content is removed in this arrangement and operating cost is minimised.