The traditional brewing methods maintained over its 200-year history have made Greene King’s ales some of the most popular in England, but it is modern PLCs that ensure the brewery is always able to keep up with demand. Brewing is a highly competitive industry and staying ahead depends on a company’s ability to look to the future and adapt quickly to changing circumstances. It is this philosophy that has made Greene King the largest and most successful regional brewer in the south of England.
The Greene King brewery in Bury St. Edmonds is one of the few remaining using traditional methods to produce its ales, but that is not to say modern technology is overlooked - behind the time honoured processes is a high degree of innovation. In particular, the brewery was the first in the country to automate its cask handling line.
With demand rising, it had become clear that the capacity of the plant needed to be increased, and a key area to address was speeding up the turn-around of casks from being returned empty to going back out full - a process that required casks to be depalletised, have their keystones (tap plugs) and shives (air plugs) removed, be cleaned and sterilised, and then cooled and refilled.
The cask handling line had been an almost entirely manual operation, though was far from an ideal working environment. Empty casks returning to the plant would have to be lifted from their pallets, and the keystone and shive removed with a hammer and chisel. As nearly all beer casks are now made of metal, one can imagine the noise levels created by this process.
Another factor in the brewery's decision to automate the line was the introduction of European legislation on manual handling. Restrictions are now in force regarding the weight of objects that can be lifted by employees, causing a potential problem with some of the larger cask sizes, even when empty.
Automating the line
The automated cask handling line is built around PLC control and a high-speed vision inspection system. For reliability, versatility and to provide the required levels of I/O, Greene King turned to OMRON for a PLC solution. The system that was installed is built around Omron CV1000 PLCs, each with three expansion racks and more than 1000 inputs and outputs.
Empty casks returning to the plant are depalletised automatically and fed onto a conveyor on their sides. The first operation is to remove the shive from the side of the barrel. Each cask is stopped at a point on the conveyor where an Omron vision system camera looks down on it from above.
With the cask in position, the PLC instructs an inverter to rotate that cask until it receives feedback from the vision system computer that the shive has been detected. As soon as the shive is detected, the inverter jogs the cask accurately into position and the PLC signals a pneumatic tool to spear the plug.
The cask is then conveyed to its next stop where the keystone is removed. Here the camera is positioned side on, and set to look for a zone just below the keystone. A light source shines from above the cask, creating a defined area of shadow underneath the keystone when it is at top dead centre. When the camera detects this shadow pattern, the vision computer signals the PLC, which stops the inverter rotating the cask, and jogs it accurately into position for a pneumatic spear to remove the keystone.
PLCs then control the entire wash sequence, during which the empty casks are put through a hot wash, a sterilisation process and finally are cooled before being refilled. The interaction between the vision system computer, the PLCs and the inverters ensures that all the detection and positioning operations can be performed with accuracy at very high speeds, boosting the throughput on the line. The automated line has the capacity to handle some 3000 casks per day, which Greene King reckons will allow it to meet anticipated demand into the next century. All the programming and maintenance of the equipment is carried out by Greene King's own engineers.
"The brewing industry is characterised by environments which change constantly to keep up with demand," comments engineering manager Simon Millyard. "And we always have to keep one step ahead, which means using the best and most advanced equipment available. The PLC system we have implemented, not only in the cask handling line but in other areas of the plant as well, is powerful and versatile enough to allow us to do just that."
For more information contact Yelland Control, 011 455 2782, [email protected], www.yelland.co.za
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