Process safety: Managing process safety with flexible IO
Integrating robust security
An industrial site is not truly safe without the right security. That’s why defense-in-depth must include physical security layers that reach not only beyond the perimeter fence, but also into the very heart of the control room. The integrated physical security element brings together often-disparate technologies to improve situational awareness and operator reaction time during an event or site emergency. In addition, digital video solutions, tightly integrated with plant DCS, can now allow cameras to function as process sensors. These systems can integrate at the database level so alarms, events, and digital recording triggers are native to the control system.
To ensure a sound protection strategy, the network and database infrastructure should also include built-in cyber security solutions. This includes an embedded and certified firewall—although cyber security goes well beyond this—starting within the end-user’s business network and extending to the core of the control architecture.
Using smart, flexible technology
Process safety applications present a range of operational challenges. In recent years, new technologies and products have emerged to address some of these issues, but in many cases they are limited and provide only partial solutions. Plant owners are seeking feature-rich solutions they can configure to meet their unique requirements. The need to accommodate legacy systems as well as new installations has underlined the necessity of compatibility and configurability. The current business climate also demands products that keep capital and maintenance costs at a minimum.
Within the plant control and safety architecture, the I/O subsystem is responsible for inputting hundreds or often thousands of different process measurements and other inputs into the system, and outputting control signals to a large number of final control elements. I/O represents one of the most significant parts of the system infrastructure, and, traditionally, a significant cost element. However, automation suppliers are working to reduce both the cost and the complexity of I/O by incorporating more intelligence and programmability into their solutions.
With the advent of flexible I/O systems, process manufacturers can now integrate more safety devices while simplifying installation and maintenance (see Figure 2). These systems employ innovative technology that allows instant configuration of I/O channels without additional hardware. They enable maximum architectural flexibility, lower cost of ownership, support SIL-3 application requirements, and are ideal for facilities that must integrate equipment, units, and other assets spread over wide geographic distances.
Developments in I/O technology offer an opportunity to liberate safety and process I/O, as well as control cabinets, from channel-type dependency. This concept enables multiple remote locations to be controlled out of a single centralized unit, with each channel of I/O individually software-configured either as analog input (AI), analog output (AO), digital input (DI), or digital output (DO). It reduces wasted I/O space and provides savings on both installation and operational costs because users no longer have to worry about having enough modules for AI, AO, DI, or DO configurations. The I/O connection can easily be configured—and reconfigured—at any time.
Plants that implement these technologies can also standardize on a universal cabinet with a generic configuration because any field signal can be connected to any I/O channel. Engineers are able to reduce documentation cost by knowing how much I/O needs to be supported, as well as its installation space requirement.
Some I/O systems are designed to support electronic (soft) marshalling, which allows the I/O module to be mounted close to the process unit to reduce or eliminate the need for homerun cables, marshalling panels, junction boxes, and field auxiliary rooms. With this new way of I/O deployment, field wires can be terminated on any I/O module or channel, regardless of signal type. It eliminates the scrambling needed in conventional marshalling approaches, thus reducing hardware complexity associated with installing, commissioning, and maintaining the system, resulting in savings on marshalling cabinets, inter-panel wiring, cabinet space, power requirements, and the traditional time needed to deploy these items.
By employing a flexible I/O approach, late changes resulting in costly project delays can now be done through remote access rather than manipulating hardware in the field. What previously took days or even weeks can be accomplished in minutes. Every day gained in the project schedule is an extra day of production. Because only one type of I/O module is needed for each project, engineers need only worry about I/O count—not I/O mix.
The latest technology advancements also limit the amount of training required for plant personnel. Only one category of I/O is needed to meet all of the input/output requirements on a typical SIS project. There are fewer interconnections with this type of solution—and consequently fewer failures—so testing and installation are easier.
Moving applications to the field
Most recently, automation suppliers have developed safety logic solvers designed to execute safety applications independently in the I/O module. Users can distribute safety logic into the field in close proximity to the process while maintaining a transparent overview. Such logic solvers safeguard the process even in the event of interruption in communication with the SIS. This approach is ideally suited to highly distributed applications, and reduces cost while increasing process availability and efficiency.
For example, in the upstream oil and gas industry, oil field operators can now implement a safety solution whereby the I/O module at each wellhead is integrated into the SIS and DCS, but can also act as a dedicated logic solver for the head if the central connection is lost. In effect, another layer of redundancy and separation is added to the system.
Meanwhile, pipeline integrity solutions and radar video surveillance for on-land facilities that allow significant savings over camera-only based solutions are expanding the scope and range of safety devices that can be integrated into the system in other areas.
Operational managers in process plants must address a host of pressing demands: worker safety, environmental stewardship, process uptime, and conservation of plant resources—and the list goes on. These challenges are stretching the limits of existing resources and expertise.
With innovations in automation technology, plants can optimize process safety systems in a wide range of installations, improve overall safety performance, and reduce capital and operating costs throughout the lifecycle of their projects.
Erik de Groot is marketing manager of safety systems for Honeywell Process Solutions. He has been active in the process industries in both process development and automation for 26 years, including 16 years with Honeywell where he started as an application engineer in Amsterdam, the Netherlands. He has a Bachelor’s degree in chemical engineering from the HTS Hilversum, the Netherlands.
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