13 March 2012
The site has a large number of Air Handling Units (AHUs), as well as water circulation pumps and compressors, contributing to a total utility spend of £1.25 million per annum. Ricoh’s energy specialist, Andy Smith, was keen to reduce energy consumption and initially trialled two ABB drives, one on just one pump and one on an AHU. These were provided on a hire drive basis by ABB Drives Alliance member, Central Group.“The results encouraged us to evaluate all possible motor-driven applications on site for energy saving potential. Our project prioritisation process evaluates criteria such as CO2 saved, technical complexity, risk and return on investment. VSD installations were subsequently identified as a key energy saving technology, being simple to install and giving excellent payback.”Some 90% of the originally identified applications have now been retrofitted with ABB drives. A total of around 70 drives run a large variety of applications around the site, with an average payback time of around six months per installation.In addition to providing energy savings, the drives have allowed Ricoh to gain better control over a number of processes. In the laboratory, for example, where the properties of the manufactured toner are tested. To achieve optimum test conditions, the temperature and humidity values within the laboratory must be maintained at constant levels. Using an ABB drive to control the laboratory air flow ensured that temperature was controlled to within 0.5°C of the set point. An ABB drive controlled humidifier ensured that humidity varies by no more than 1.5%. “An important feature of the drive in this application was flux optimisation,” said Smith. “Even at 50Hz, with no speed reduction, this reduced the power consumption from 5.5kW to 3kW.”Running at 35Hz, the power consumption was further reduced to just 1.6kW, providing a payback of just three months.As Ricoh’s experience of using ABB drives has increased, the company is applying them in more applications. “We use three drives to synchronise two conveyors with a 22 kW plastic granulator that grinds plastic parts for recycling. Linked to a PLC, this allows us to run the granulator on demand. Run time has been reduced by 95%, cutting its energy use and increasing equipment service life,” said Smith.Other features of the drives that have offering benefits in this application is the supervised relay output function, which allows the drive to control motors dependant on the status of connected equipment and Modbus compatibility, which allows control and monitoring of applications over a PLC network.“The timer and constant speed functions have proved very useful,” said Smith. “Combining these features, we can run the AHUs at varying frequencies over the seasons. In many cases, we run AHUs at 45 Hz in the summer, 30 Hz during winter and at 35 Hz during other periods, all automated within the drive.”Another energy saving feature employed by Ricoh is the sleep mode function, which is programmed to put the drive into a ‘PID sleep’ mode whenever there is no demand from the process.“The latest ABB drives now have energy calculators that display total energy consumption on the control panel screen,” said Smith. “We are using this to increase energy awareness among staff by showing just how much energy applications such as granulators actually use.”Ricoh’s Capital Equipment Specification now assesses the feasibility of installing VSDs on all new equipment. “We try to purchase equipment that can benefit from VSD control. Having previously proved the extensive savings that can be realised, we don’t want to miss out on further opportunities to save even more energy,” concludes Smith.
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