Save and prosper

In an effort to cut energy costs and reduce material waste, manufacturers — from potters to food producers — are constantly seeking ways to improve control of their production processes.

Leading automation giants, such as

and US-based

, are some of the main benefactors of recent trends that have driven up profits for those selling process control systems around the world.

Manufacturing is continuing to flourish in emerging economies —especially in China. According to a report published last month by US-based advisory group

.

There are about $65bn (£36.5bn) worth of installed automation systems in the world nearing the end of their lives. So there is great potential for control systems sellers.

the increased automation demands of China is illustrated by the recent announcement of a contract between Emerson and the Huaneng Group for the use of the company's digital automation products at new coal-fired power plants at Haimen in Guangdong Province.

Emerson will supply its PlantWeb digital plant architecture with Ovation expert control system and its AMS Suite predictive maintenance software to operate at the heart of a system, including intelligent field devices such as Rosemount 848T temperature transmitters and 3051 pressure/level transmitters. It is part of a contract to build six 1,036MW plants, with more than 6,000MW of generating capacity.

These plants are what are described as 'ultra-supercritical' — that is they use clean-coal technology and operate at elevated steam temperatures and pressures for maximum efficiency. It is claimed that the use of these technologies can boost the efficiency of the coal-based electricity generation process by more than 50 per cent, with superior environmental performance.

For the first phase of the build the Ovation software will monitor and control the boiler and the sequence control, electric control, modulating control, furnace safeguard supervisory, and flue gas desulphurisation systems and balance-of-plant processes for the first two units.

It will also provide feedwater pump electro-hydraulic control and interface with the Dongfan turbine controls and Programmable Logic Controllers (PLCs) to control soot blowing, dust removal, ash and slag handling and plasma ignition.

The hardware, including 64 Ovation redundant controllers, 10 operator stations, and four engineering stations, will all be connected to the system via fieldbus (both Foundation Fieldbus and Profibus DP) networks.

The AMS Suite software will streamline the configuration of the intelligent devices, leading to claimed cost savings and increased start-up efficiency, as well as taking plant data to help ensure the efficiency of the operation and maintenance activities.

Not all the business is in China. There are still plenty of control system applications here in the UK. For example, Denby Pottery in Derbyshire is being fully automated with the help of Mitsubishi Electric automation systems.

Many separate processes need to be controlled using separate systems. The mixing of clay slip, the raw material used in the production of the pottery, for example, is carried out using a Mitsubishi inverter with information from gear-tooth sensors sending positional information back to a PLC that controls the mix sequence for the machine, which is able to mix some 1.5 tonnes of material at a time.

An acid dosing system, part of the slip blending process, is again controlled by a PLC, this time a Mitsubishi FX with an E50 Human Machine Interface (HMI) — a similar arrangement to the controller for the next stage in the process, effluent treatment, which uses an FX2N PLC.

As well as the clay slip, the final products need glazing, an operation that needs complex control of more than 500 recipes. For this job Denby uses Mitsubishi's Q series PAC (Programmable Automation Controller). Finally, the kilns are controlled by separate PLCs for the burner and haulage functions, all feeding into an HMI on the shop floor.

What was once a completely hand-crafted product is now a highly automated process. Indeed, the pottery is moving towards integrating its plant control functions into a Manufacturing Execution System in the near future for even more automation.

High levels of automation and the need to use a large amount of plant data are also behind the recent installation of high-speed managed ethernet switches to the fibreoptic network linking plant components to the supervisory control and data acquisition (Scada) system at Irish Distillers' East Cork distillery.

Producing both grain and pot whiskeys, the distillery found that its old set-up using a fibreoptic network with star topology was becoming a limiting factor on its Scada system, with slow connections even when using a 100Mbit/sec network.

The installation of GarrettCom-managed ethernet switches run by the company's MNS software now link the production areas to the Scada system over a fibreoptic ring at gigabit speeds.

The system offers RS-Ring redundancy technology, which is claimed to provide fast fault recovery in ethernet local area networks — even over the large distances separating the various parts of the distillery.

These control operations are just as necessary in food production — which has meant big business for Hydramotion, the York-based process and portable viscosity measurement system specialist. The company is now working with one undisclosed UK manufacturer of 'chocolate products'.

The manufacturer has installed a series of Hydramotion XL7 online viscometers on pipelines to its mixing tanks. In this process the meters operate with impunity to plant noise and vibration and are claimed to give reliable and accurate viscosity measurement.

As part of the production process chocolate must be cooled in a controlled way to promote the formation of small, stable fat crystals — a process familiar to all chocolate chefs as 'tempering'.

If the crystals are small enough the chocolate will melt at about 35ºC, in the mouth, not in the hand.

Measuring chocolate viscosity is important as it is directly dependent on the fat content and the degree of tempering — monitoring the viscosity gives an idea of how far the chocolate is tempered.

This means real-time changes can be applied to the process, maintaining product quality and minimising waste.