How do you control the flow of water in your drinks bottling line? How do you manage the cold air blowing into your chiller unit? How do you regulate the amount of steam you're pumping into your steriliser?
In most food factories there will be a valve somewhere. But, says Gary Busby, using a valve to control the flow of air, steam or water is as bad as driving your car with your foot on the brake. You wouldn't drive with the throttle flat out and use the brake to control your speed, would you? So why keep the pumps and fans in your food factory running at full speed and use a valve to control flow to the processing line?
Running pumps and fans at full speed wastes thousands of pounds a year in energy, says Busby, who is UK food industry manager for motor and drives manufacturer ABB. He says that a centrifugal fan or pump, for instance, running at half speed consumes only one eighth of the energy needed to run at full speed.
What this means can be seen at the Heinz factory at Kitt Green in Wigan. Here Heinz is using ABB variable speed drives to control eight air fans on four boilers in its new gas-fired steam raising plant. By being able to match the speed of the fans to its steam demand, Heinz expects to save 14% on its energy bill. This is a huge saving for a factory that generates over 100t of steam an hour for space heating and for sterilising over 1.3bn cans a year.
Real-time analysis
But energy saving motors and drives are not the only developments that are beginning to excite the food industry. Advances in automation mean that almost every new piece of factory equipment now contains some form of intelligence, so that manufacturers can collect and analyse data from the factory floor in real-time. Even 'legacy' equipment such as old motors can now be retrofitted relatively cheaply with intelligent sensors to detect and pinpoint breakdowns, as well as to flag up incipient problems such as increased motor current or overheating in control panels.
All this integration and networking of data in real-time gives companies the ability to track and trace ingredients and processes to help comply with food traceability legislation. And by being able to flag up potential equipment problems, food factories can now sharpen up their maintenance procedures and reduce stocks of spares.
Also, the latest factory data communication networks and protocols (fieldbuses) such as EtherNET enable shopfloor information to be integrated into enterprise-wide management systems. This means that customer orders coming into a factory can automatically update and reconfigure processes and production lines in real-time to meet demand.
Energy savings
Despite steeply rising energy prices and government incentives to put in energy efficient motors, too few food factories pay enough attention to the energy consumed by their electric motors, suggests Busby.
"In the food industry, the priority is producing product. Saving energy by better control of motors is not the top of most production managers' priorities," he says. Yet big savings can be made.
Electric motors are rated Efficiency 1, 2 or 3, according to their energy efficiency, with Efficiency 1 motors being the most efficient. "Just by changing an Efficiency 2 motor to an Efficiency 1 motor you won't save tens of thousands of pounds a year," says Busby. "The key is to have a motor management policy and to look for variable torque loads such as pumping water or blowing air, which allow you to reduce the speed. Turning down the speed of the drive a little bit can save a lot of money. What we say is open up the valve fully and use a variable speed drive. It's like driving a car - take your foot off the brake and slow down using the throttle."
According to ABB the torque or turning force needed to pump air or water is proportional to the square of the volume of fluid being pumped. So reducing the pump speed to 80% requires only 64% of the torque. And to produce 64% of the torque only requires 51% of the power. So reducing the pump's speed by 20% actually cuts energy consumption by 50%, says ABB.
"We visited a brewery recently and identified energy saving applications which would cost £100,000 in new drives. But the pay-back period was just 1.8 years," says Busby.
Terry Siggins is UK food industry manager at Rockwell Automation. To him, automation means providing the customer with the data to know exactly what is happening on their factory floor and giving them the ability, or rather agility, to react rapidly to changing demands from their customers.
"At the bottom end you need to know what's going on in your plant. Ten years ago people would only have had a subjective idea of what their overall equipment efficiency was. They would not have been able pinpoint exactly where production problems were occurring, which key bits of the plant were failing, or whether the same failures were happening on a regular basis."
Today, he says, thanks to developments in automation, factory managers can get a good handle on what is happening during a process - where the raw materials came from, who made what, where the products went, and what the downtime, planned and unplanned, was.
At the other end of the manufacturing process, food companies are constantly having to readjust their plant to get new products and new formulations on to the supermarket shelves as soon as possible. And they all have to be the same whether they come out of their plant in the UK or their factory in France, says Siggins.
"The pressure now is to connect the manufacturing plant through to the customer order coming in through the door so that you are able to quickly adjust and change what you are making," says Siggins.
The ultimate aim for the food industry, he suggests, is the development of just-in-time manufacturing, paralleling what has been common practice in the car industry for years. "The food industry has a greater variety of products to deal with than the car industry.
However, the real problem is that there isn't a standard way of making food. Even within the same company, even in the same plant, you don't get the same meat pie from the end of each line."
S88 batch standard
The internationally agreed standard on how to define recipes independently of the equipment used - the so-called S88 standard - is shortening batch cycles, reducing time to market and improving process line productivity.
Thanks to S88, engineers no longer have to be called out to recode or reprogram automated process and production equipment every time there is a change to a batch recipe. It can now be done easily in software, often by the line operator and is rapidly becoming best practice for food batch manufacture.
S88 is a way of defining a recipe in modular steps so that it can be programmed into a process line irrespective of who manufactured the line or supplied the control logic. Its biggest advantage of using this method is that it enables a plant to produce a range of products or recipes by using equipment in different ways and by passing batches of ingredients between different groups of machinery.
Unilever and Nestlé were among the first to implement S88, but it is now rapidly becoming best practice within the industry, says Siggins. "You separate the recipe from the equipment you've got so that you can make things - such as meat pies - in a standard way on several pieces of equipment, but still guarantee that what you get out at the end is all made the same way."
A recent major development has been the adoption of safety related factory automation fieldbus standards such as PROFISafe and SafetyBUS. They allow automation and machine safety data to run on the same communications networks, says Andrew Cowey, who looks after industrial automation systems at Siemens Automation.
"Rather than have two separate circuits, one for safety relays and one for control data, they can now be integrated on one bus called SafetyBUS, for example." Safety equipment no longer needs its own hard-wired networks. It can now be controlled in software using the same fieldbus systems as standard automation data, says Cowey. FM
KEY CONTACTSABB 01925 741 111Rockwell automation 0870 242 5009Siemens Automation 0161 446 6400ISA 001 919 549844