Vivergo Fuels has selected Ekato Group to provide side-agitators in order to aid fermentation at its new 27-acre biorefinery plant. Ekato claims that its side entry agitators will be used for the continuous suspension of solids and homogenisation of tank contents, and offer an efficient mixing solution together with considerable savings compared to traditional top entry agitator technology.
Vivergo Fuels is currently building a biorefinery in Saltend, East Riding of Yorkshire, which, once fully operational, will employ 70 full-time staff. Located in the UK’s wheat belt area, the refinery will consume over 1 million tons of wheat per year, producing 420 million litres of biofuel from 2010, together with 500,000 tonnes of animal feed from the wheat protein and fibre left over from the fermentation process.
According to Ekato, installing multiple side-entry mixers is more straightforward than installing top entry agitators, and it does not require additional equipment such as internal baffles, thereby reducing the cost per vessel.
Stewart Murray, engineering manager, Vivergo Fuels, said: “Ekato demonstrated a good understanding of the complex mixing issues surrounding side entry agitators and their experience of supplying a wide range of agitators into the bio-fuels industry combined with an ability to carry out pilot scale trials were key factors in selecting the company’s technology for our plant.”
Ekato said that as a design option, a ‘shut-off’ device is also available, which allows the mechanical seal to be serviced or removed while the vessel is full of product, reducing maintenance costs and servicing time. In addition, side entry agitators enhance process efficiency and allow the user better control over the mixing process, avoiding deposits of solids in the tank.
Mr Murray added, “Top entry agitators would have been prohibitively expensive due to the need to strengthen each vessel to transmit the torque and bending moments. Ekato’s side entry agitator design was consistent with our aim to design an installation which had minimal crevices and would be straightforward and economical to implement and maintain.”
Ekato said that in order to design a tailored solution for Vivergo, its design engineers followed a ‘rigorous’ research and development process, building a pilot model fermenter with scale agitators and vessel internals, including filling and drain points to confirm agitator design to achieve the required degree of particle suspension.
Following this, the team simulated flow velocities and solids concentration distribution of the pilot set-up, using computational fluid dynamics (CFD) modelling as the validation method. Using both pilot modelling and CFD techniques, Ekato defined the optimum agitator quantity, position and shaft angle to the vessel wall to suit the geometry of each vessel.
Finally, the mixing requirements for the full scale plant were calculated, using the company’s R&D findings, and with a further CFD study of the plant scale, Ekato claims that its can accurately predict the results for Vivergo Fuels’ new fermenters.
John Smith, managing director of Ekato, said: “Our R&D process is integral to how we build solutions for our customers. Our thorough simulation and testing techniques allow us to fine tune the equipment to fit our customers’ needs.
“Each agitator is designed on the basis of the mixing task in hand: for blending, the viscosity ratio is the determining factor, together with the settling behaviour of the grains, which is influenced by fluid density, grain size, moisture content and settling velocity. Our comprehensive approach allows us to provide accurate and efficient equipment with minimal investment.”