The machines of the future

Clay Technology magazine
9 Feb 2015

Improvements in machinery are key to keeping the market growing. Rhiannon Garth Jones takes a look at some of the new products for the heavy clay industry. 

One of the most marked shifts in public policy around the world over the past decade has been in energy creation and use, and associated emissions.

By November 2014, even China – previously reluctant to commit to any targets – agreed to start reducing emissions from fossil fuels. One significant aspect of this change in policy has been an increased focus on energy efficiency, aided by uncertainty over fuel prices.

With the EU Energy Efficiency Directive mandating energy audits for large enterprises within all member states by December 2015, energy efficiency has been raised even higher on the agenda across Europe. Although actual savings are not required to be implemented, many companies are currently trying to get ahead of the curve and in order to make gains in this area, new machinery has been introduced and different forms of fuel investigated across all industries, including the heavy clay sector.

It was clear at ClayTech UK 2014 that energy was on the mind of industry members, with Miguel Moix and Santi Amposta of Beralmar, in Barcelona, mentioning several alternatives to natural gas that they have adapted their kilns and dryers to. Mineral coal, biogas, recycled cooking oil, micronised petcoke and olive pomace can all be used, and feedstocks can be combined to reduce cost.

Beralmar’s biomatic firing system, for instance, uses biomass for firing as well as heat generation in the drying process. The balance of carbon dioxide emissions when using biomass is neutral, and it is a cheap fuel option when used in compatible systems.

One firm that has committed itself to increasing the energy efficiency in its brick plants is German-based Keller HCW, which has worked to create a new sustainable kiln concept. The firm believes energy consumption of a roof tile plant, for example, can be reduced by around 30% with the principle of the counter-travel kiln.

Keller’s Enviro-kiln ensures that the solid-solid energy transfer operates successfully, meaning that the product flows travelling side by side are limited in their geometry, that the convection is forced and that the heat transfer by means of radiation is used as efficiently as possible.

To provide a transverse circulation, the fans are arranged in the convection area over the length of the kiln.

The re-circulation fans stop after a defined limit temperature is reached, as the radiation part is now predominant and takes over the main heat exchange. Final firing is the same as conventional kilns.

Another Spanish firm, Verdés, has introduced a new range of Magna extruders, which aim to enhance functionality and efficiency. The modular mixing zone has an adjustable pitch knife system, ensuring adaptability to varying clay mixtures. Reduced wear rates have also been achieved by giving a new geometry to the mixing knives and replaceable shafts and trough liners give the machines better functionality.

To maintain energy efficiency, the axial bearing has been over-sized to run at continuous high pressures and the line has a new digital system to protect the thrust bearing, which uses load cells instead of an hydraulic system and is more precise than referring to the plastometer reading.

Bongioanni, an Italian firm, has also focused on innovative extruders. Its Tecno range has reduced power consumption by 20–30%, using extruders made from electro-welded steel and stabilised in a kiln to relieve the welding tensions and increase strength. The vacuum sealing is ensured by a tested system, consisting of two sealing rings made from hard plastic that work on chromium-plated sleeves assembled on the shaft of the augers.

The feeding reels are separately driven by two gear motors and held in two high-resistant spheroidal cast iron shells with wear inserts in Ni-Cr cast-iron. The wear parts are coated with interchangeable sheet plates and the pipe of the auger is lined with Abrastrong and reinforced with metallic fibres to reduce maintenance costs and machine downtime.

German firm CTB Berlin’s range of True Blue burners focuses on saving energy in gas-fired intermittent kilns and furnaces, which remain necessary to many companies. For these burners to function most efficiently, they have to be able to operate above their minimum outputs at low temperatures – sometimes around 60°C – and serious problems occur below 10% of efficiency. To compensate for the heat input required, a high amount of diffusion air is needed to maintain the temperature, wasting energy. Additionally, cracks can be caused by the flow rates of burners.

The firing technology of CTB’s range uses simultaneous measurements of temperature and pressure-compensated gas and air-flow volume, barometric pressure and humidity, automatically directed the required levels to each burner without the need for manual adjustments. Making intermittent kilns and furnaces energy efficient and economically viable is, for many firms, a key improvement.

Energy efficiency can have a number of tangible benefits to companies beyond increased profitability, including a boost to stakeholder credibility and an edge in attracting new, environmentally-conscious employees.