Digital plant architecture provides flexibility and reliability for complex laboratory processes

06 September 2011

The Gran Sasso National Laboratories in the Abruzzo region of central Italy are situated around 1400 m below the summit of the Gran Sasso mountain. Owned by the Istituto Nazionale di Fisica Nucleare (INFN), the laboratories have been created to carry out experiments in a setting with a low radioactivity level. The rocks above the laboratories act as a shield against cosmic radiations and make it possible to measure very weak radioactive signals from materials being tested.

A huge variety of experiments are carried out at the laboratories. For example Opera and Icarus, the connected particle accelerator at CERN in Geneva, produces a beam of high-energy particles that are sent here for further experiments.

The complex nature of the experiments undertaken requires innovative solutions have to be found when practical problems arise. For example, when a new procedure for purifying a liquid chemical was required, Emerson’s digital plant architecture helped to obtain process results which exceeded industrial standards, and met the exacting standards required of a laboratory.

Emerson’s PlantWeb architecture uses open communication standards to link devices, systems, and applications in a plant-wide network to ensure process and equipment information is available wherever it's needed.

In the late 1990s, INFN was introduced to Emerson’s DeltaV digital control system which uses the PlantWeb architecture's predictive intelligence to provide control power, flexibility, and ease of use for batch, continuous, and hybrid processes. INFN applied the system to an application and found it to be reliable, flexible and easy to program. It also had scalability that would enable it to be adapted to suit expansion and future developments at the laboratory.

The Borexino experiment
The Borexino experiment has been constructed under an international collaboration to observe low energy particles in real-time. INFN wanted to ensure that the various parts of the equipment for this international project would be able to communicate with each other and, following a pilot project to prove its suitable for the task, impressed upon the researchers the importance of communication between the different parts of the system Emerson’s digital architecture was chosen as the platform for integrating and controlling this diverse and complex equipment. Process variables from the transmitters and the signals to the control elements are all managed by the system. Process data is displayed on operator consoles in a simple graphical form.

DeltaV makes it easy to generate dedicated graphical displays enabling process operators to monitor the activity of the whole system. When an alarm goes off, the operator is first alerted acoustically and then visually on his screen.

For critical parts of the system, the alerts also set off an acoustic alarm and notify the persons designated to manage the breakdown via a video message and by text message. This procedure is triggered by a script written in Visual Basic programming language

All control is based on 4-20 mA analogue signals, with digital HART communications being used over the same pair of wires for predictive diagnostics and calibration.

Fisher control valves with FIELDVUE digital valve controllers are used on critical parts of the plant. Using AMS Suite predictive maintenance software, diagnostic and status information is monitored over the HART network and used to provide an early notification of problems that could affect the process.

The Borexino project focuses on reliability, and the Fisher control valves, Micro Motion Coriolis flowmeters, and Rosemount pressure and temperature instruments that are also part of the PlantWeb architecture have proven to be 100% reliable, resulting in zero breakdowns over a ten year working period.

Initially the system used on the Borexino experiment comprised around 100 tags. This has since been expanded to 500 tags. As well as keeping current process variables under control, the system incorporates a historian that enables data to be kept on file and analysed after the experiments have been completed.

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