Salt Union gets ABB award for energy saving

Salt Union, one of Europe’s largest salt producers, has received ABB’s special award for energy savings, recognising its outstanding achievement in saving over £100,000 a year in energy costs. The award was presented to electrical plant improvement engineer Dave Mullin at Salt Union’s site in Runcorn, Cheshire, where the company can produce up to one million tonnes of salt per year.

The savings were achieved by replacing a fixed speed 337 kW fan and motor, the largest on the site, with a 132 kW fan and motor coupled to an ABB industrial drive. The investment cost was just £50,000.

“We knew the fan system was oversized but thought it would cost much more to rectify,” says technical manager Ian Bradley. “When we realised the payback time was only a few months, we immediately decided to go ahead with the investment.”

The installation of the new fan system has saved about 10% of the total energy demand at the site.

“Energy savings are becoming a priority,” says Bradley. “Last year we were paying 20 pence per therm for the gas, now we are being quoted over 40 pence for next year, more than a doubling of the price in just one year.”

As the company generates its own electricity from a gas-fired CHP plant on the site, the rising price of gas is having a direct impact on operational costs. The energy demand is about 5MVA for the site and makes up a substantial part of the variable costs for the company.

“The cost of energy usage is one of the few factors we can influence,” Bradley continues. “The price and demand for salt is pretty constant, as is the price for the brine the salt is made from. Energy savings can therefore make a significant contribution to the bottom line.”

The new fan, motor and drive combination is fitted to a dryer in a filtration plant. The equipment was originally used for producing a different grade of salt, however for the new type of salt, a lower volume of air was needed. When used with the old fan system, the surplus was simply choked off with a damper, which was only opened by 5%.

“As the application had changed, we intended to purchase a complete new filtration plant, however the cost for this was in the region of £1 million, so we decided to keep the old plant running for a bit longer,” says Mullin. “Investing in a new fan system would keep the old filter going for another five years.”

Mullin wanted to eliminate the damper and use a variable speed drive on the existing dryer. He contacted ABB Drives Alliance partner Central Electrical in Liverpool and with them, worked out that only one-third of the power was required.
“We measured the energy consumption of the application to find out the size of motor needed and realised that substantial savings could be made, giving payback in only a few months,” says Shaun Sutton, sales manager at Central Electrical.

As well as saving costs, the new fan, motor and drive combination is also reducing CO2 emissions to the environment by 704 tonnes per year.

“This shows the impact variable speed drives can have, says Steve Ruddell, general manager drives and motors, ABB. “There are many applications across industry where motors, oversized for historical reasons, are wasting energy year after year.”

“We were expecting having to invest around £100,000” says Mullin. “We were pleasantly surprised when we worked out the full costs for the project. In the end, we got payback on energy in less than a year, which was much better than expected.”

The variable speed drive also gives better control of the heating process, ensuring that the temperature does not get too high. If this happens, the salt crystals can burst and cause dust problems.

David Mullin is now looking at other energy saving measures, for instance using a variable speed drives to optimise the energy consumption of the Evaporation Plant vacuum pump system. He is also looking at another project to save energy by generating power from the discharge of water from the process, which amounts to 7,500 tonnes per hour.

Salt has been made at the company’s site at Weston Point, Runcorn, since the late 1800s. The company originally consisted of 64 separate salt companies which converged onto the present day site. Taken over by ICI in 1937, it was sold again in 1992, together with its rock salt mine in Winsford, Cheshire. Today it is part of global salt company Compass Minerals Inc, USA, which makes and sells over 9 million tonnes of salt each year.

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    Dave Mullin, electrical plant improvement engineer at Salt Union in Runcorn, receives ABB’s special award for energy savings from ABB’s general manager for drives and motors Steve Ruddell, left and Shaun Sutton, sales manager at Central Electrical, right
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