A large-scale rotational moulding installation benefits from advanced process heating technology
An expert in the field of process gas burner systems was recently involved in a major project that showcases the merit of its solutions. Rotational moulding specialist Rotomech undertook the project, which involved the use of gas burners from Lanemark Combustion Engineering.
Lanemark forced draught (FD) burners were specified as a key element in this large-scale ‘rock-and-roll’ system – the latest facility to become operational at Etills, a firm that produces a range of water storage tanks, vessels and containers and known for its Ecosure brand.
“The rock-and-roll design enables high-quality rotational moulding results to be achieved as it allows material to be distributed evenly and consistently,” says Karl Meekins, Rotomech’s MD. “Highly accurate process heating is an important requirement of such a system so the control capability of the FD design is a key factor.” The installation centres on a tubular heating chamber, mounted over a floor-located pit, which both spins and tilts up to 45° vertically to achieve the rock-and-roll motion.
“This houses a steel or aluminium mould, which in turn contains plastic powder – typically medium density polypropylene,” explains Adrian Langford, Lanemark’s general manager. “The internal chamber temperature is raised to some 285°C, which, through convection, elevates the mould to between 90 and 180°C, depending upon application needs. Over a cycle of up to 60 minutes, this enables the external walls of the water vessel to be formed ahead of cooling within the chamber and crane handling for onward processing,” he adds. Vessels of up to 4.6m in length and of varying wall thicknesses can be produced.
Two Lanemark FD15-C burner systems were specified for the project, each rated at 600kW. Their design not only maximises heating efficiency, but also allows excellent control to be achieved to optimise both heating reliability and consistency. The level of control capability that is at the heart of these burners is also a key factor at the site – a temperature variation of only ±5°C is achieved.
Lanemark also supplied two variable speed drives, each rated at 11kW, for the process fans – both of which were linked by Rotomech to the master control panel located alongside the installation. “These control fan speed and frequency, which also helps to ensure temperature accuracy and control are both as efficient as possible,” explains Meekins, who also points out that the burners’ thermostatic control is centred on a series of temperature probes linked back to the control interface.
The rock-and-roll design is a bespoke system that called for both Rotomech and Lanemark engineers to work closely to meet exact customer needs. The rapid heat-up capability of the burner designs also plays a major role with the new installation because, following cooling, each new cycle has to start from ambient – clearly the more rapidly operational temperatures can be reached, the more cost effective each operation can become.
This new facility is the latest in a series of rotational moulding installations undertaken by Rotomech at the site, including a series of ‘carousel’ installations, each of which also takes full advantage of the process gas burners’ efficiency.
“This is one of the largest rotational moulding machines of its type ever installed in the UK and was designed specifically to provide Etills with highly reliable process control that plays a key role in a wide range of its manufacturing processes,” reveals Langford. “The variation of products that the company manufactures – up to 7,000 units per year – needs to be reflected in the versatility and consistency of its processing systems. This is an objective that we are confident is being fully realised by our work with Rotomech and the rock-and-roll system design.”