by Brian Taylor, Canongate Technology Ltd

William Grant&Sons Distillers Ltd has been operating its Customer Service Centre at Bellshill, near Glasgow, for five years. The Vat Hall at this site processes almost 50 million litres of spirit per year, whilst preserving and maintaining the traditions of the Scotch whisky industry. The engineering and production teams at the site have invested in new technology to ensure that the production process is optimised and that the product quality is of the highest order.

Background

The previous control system comprised three Siemens S5 100U PLC's with a DOS-based SCADA system and a Siemens S5 115U PLC with keypad interfaces. The systems were stand-alone with hardwired interlocks. Due to growth in the company's business, William Grant wished to install a Windows NT based SCADA system, with an integrated fieldbus PLC network and MTE Turck Sensoplex 2 Exi I/O for the zone 1 hazardous area in the Vat Hall. It was also necessary to actuate an additional 49 control valves and position check a further 100 valves.

In 1995, Canongate had installed VesselCheck LS vat level and strength measurement systems on five external storage vats, which allowed the Vat Hall team to discontinue manual sampling. The intention was to progressively add vats to the system.

Following the installation of the VesselCheck LS, William Grant was issued a company-wide concession from HMC&E to discontinue manual sampling and use vat level and strength data for official reporting purposes. This led to the installation of the system on spirit vats at the Glenfiddich distillery in Dufftown and at the grain distillery in Girvan, Ayrshire.

Automation Overview

Following consultation with William Grant engineers, Canongate put forward a Functional Design Specification, which encompassed the following:

• Control and route checking from tanker intake to the bottling vats.
• Overfill protection of vats.
• Flow monitoring.
• Continuous background scan of automatic valve positions.
• Automatic measurement of vat strength and volumes.
• Automatic control of spirit reduction.
• Transfer quality checks.
• Bottling vat information log and display including rotation number, colour and quality.
• Logging of all route transfer information.

The system was also designed to control and monitor spirit transfers from the tanker bay to either reduction vats, storage vats, gin vats, or vodka vats. This element of the work was crucial as the route selected from operator terminals would need the following checks:

• Ensure all valves are in the correct position.
• Required transfer pump operating.
• The selected destination vat could accommodate the proposed volume of liquid.
• Quality of the liquid already in the tank was compatible with the selected quality.

Installation

The installation of the new system was critical, as interruptions to the process had to be avoided. In preparation for this, Canongate carried out a full site survey checking the:

• Condition of the high level probes already on the vats.
• Condition of the flowmeters.
• Security of internal electrics of existing control panels.

This was part of a turnkey contract that included the electrical and mechanical installation of the new control system.

Canongate engineers replaced the S5 PLC's with a Siemens S7 PLC using Profibus DP to communicate with S7 ET200 I/O and the MTE Turck Sensoplex 2 I/O. The Human Machine Interface to these devices incorporated two Siemens WinCC SCADA terminals with the screens designed by Canongate engineers, and the engineering and process teams at William Grant&Sons Distillers Ltd working together.

The new PLC I/O was installed in the existing control panels, while the MTE Turck I/O modules were installed locally to the valves in the zone 1 hazardous area in the Vat Hall.

The phased changeover from the old control system to the new control system was made with no production time losses during a busy period. Power and signals to each module are via a coaxial cable, thus minimising installation costs and time.

The VesselCheck system has been expanded to monitor level and strength on a further five vats, incorporating a communications link to the control system, improving further the overall control facilities of the plant.

Operation Benefits

The strong partnership that was forged between the two companies ensured that the plant control was changed with no disruption to production during a very busy schedule. The system now offers a comprehensive range of control features enabling the process team to track easily operations and schedules.