PROCESS AUTOMATION FEATURE MAKE ROOM FOR ENERGY SAVINGS


A PLC-based control system from Mitsubishi Electric is tipped to save a mushroom producer approximately £33,000 a year


W


hen one of Ireland’s largest mushroom producers, Codd


Mushrooms, wanted to save energy and boost reliability within its factory chilled water system, it turned to Mitsubishi Electric and its systems integrator partner MPAC for a solution. The resulting PLC based control system using Mitsubishi Electric variable speed drives to control the various pumps, has delivered a saving of over 5400kWh in one week, which will amount to €40,000 (approx. £33,000) per year. Codd Mushrooms’ production and


packing facility comprises a vacuum cooling system which takes products from a field temperature of 20°C down to 3°C in just 20 minutes, a process which ensures two days extra shelf life. The company’s commitment to


sustainability means it is always looking for further energy savings. For example, it was keen to investigate whether energy savings could be made in the factory chilled water system, and whether reliability could be increased. The chilled water system serves the requirements of various production areas, which all work independently and need varying amounts of heating or cooling. Water is initially cooled to 5°C, stored and pumped through heat exchangers in the production areas and then returned to the chiller for recooling and reuse. To investigate the possibilities, Codd


Mushrooms called in local Mitsubishi Electric system integrator MPAC. Director Matt Pender, said: “Because the system didn’t have any way of knowing what the


demand would be, it was always working at full capacity. As such, it was only ever working efficiently when demand was equal to 100% of capacity. “In reality, demand at the plant is


dynamic. It rarely needs the full capacity, and even if it does it still won’t be a constant demand. The system demand varies hour by hour and day by day, with a number of different influencing factors, including the number of production rooms calling for cooling, the stage of the cycle the rooms are in, the external ambient temperature dictated by the local weather and the humidity.” Even at zero demand, the old system


would continue pumping the maximum volume of water and, even if it wouldn’t be drawn through the heat exchangers, it would still warm up en route. During its investigation of the chilled


water system, MPAC noted that it consumed 6115kWh of energy over a seven day monitoring period. Although a theoretical maximum


efficiency could be achieved by stopping the system when there was no demand, this would lose the ability to detect when demand increased again. “If we didn’t keep


Using progressive automation, Codd Mushrooms has been able to advance its production as the business has grown


some sort of buffer of chilled water,” said Pender, “we would have a very ‘laggy’ system that was slow to respond when a given production area called for cooling.” The solution developed by MPAC lay in


The PLC-based control system using Mitsubishi Electric variable speed drives has delivered a saving of over 5400kWh in one week


ACT ON DATA, RATHER THAN SIMPLY MANAGE IT


Emerson has introduced the AMS ARES Platform, designed to prioritise and deliver asset and device health data, enabling maintenance decisions to be made that will help increase operational and asset availability. Anywhere and anytime, users can securely access and share key data, with asset health summaries available on traditional desktop PCs, laptops, smartphones, and tablets − inside or outside the plant. Part of Emerson’s Plantweb digital ecosystem, the AMS ARES Platform gathers data from multiple


sensing technologies, and provides a holistic view of the current health status of plant assets. Persona-based access to information ensures the right personnel have instant access to clear health


overviews of assets that are relevant to them. A streamlined dashboard and embedded tools for assigning prioritisation based on criticality allow users to quickly determine the urgency of an issue. “Plant personnel need to know the health of their assets in relevant time to when they need it,” said Duncan Schleiss, vice president of business development, Emerson Automation Solutions. “Emerson is committed to delivering solutions that provide information to those that can fix problems before they become production issues. By providing a secure, flexible and easy to deploy platform that communicates with many types of assets, asset health is published and available to all with minimal effort and in relevant time.” The AMS ARES Platform marks a measurable shift away from managing


data and toward delivering actionable insight. Emerson Automation Solutions


www.emerson.com


between, with a calculated demand system. The various pumps in the system – including the primary pump that circulates water between the chiller and buffer tank, the secondary pump feeding the lower side of the factory, and the twinset pump feeding the upper side – were all fitted with Mitsubishi Electric FR- F740 variable speed drives. These were linked to a Mitsubishi Electric MELSEC Q series PLC via CC-Link. All process variables are measured by sensors and data is fed to the PLC via Mitsubishi Electric STLite remote I/O units. The PLC calculates the actual demand and appropriate response, adjusting the drives accordingly. By controlling the pumps, the flow of water is always proportional to demand. Process visualisation is via a Mitsubishi Electric GOT series HMI. “With this system, the pumps are operating more efficiently, and the amount of warm water returning to the buffer is significantly reduced,” said Pender. Centrifugal pumps operate on a cube law


with regard to energy consumption, so even small reductions in speed can quickly deliver significant energy savings. Following installation of the new


control system, MPAC monitored demand over a second seven day period, and saw energy consumption reduced from 6115kWh to just 664kWh – a saving of 5451kWh. The drives have also reduced electrical and mechanical stresses on the pump and motors and eliminated water hammer, so should reduce maintenance and repair costs. Raymond Codd sums up: “MPAC have


helped us to automate our processes using a range of industry leading solutions from Mitsubishi Electric. These have increased our productivity and overall efficiency.”


Mitsubishi Electric gb3a.mitsubishielectric.com


 PROCESS & CONTROL | NOVEMBER 2016 39


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