Integrated System Improves Operations

Figure 1. Operator discusses hydrogen peroxide unit with author (standing on right).

For the A.O.A. II unit we wanted to integrate the basic process control system (BPCS) and the safety instrumented system (SIS) because we believed this would offer both financial and operational advantages. We selected a System 800xA from ABB. That company’s track record with projects at other Atanor sites greatly influenced our decision. We began working with ABB almost 20 years ago when our acetic acid plant in Bardero updated its instrumentation.

The A.O.A. II control and safety system includes five workstations with local and remote screens for operations, engineering, information management and maintenance. The controllers utilize more than 2,000 input/output (I/O) points at multiple remote locations. In addition, the system integrates more than 300 field devices having Profibus or HART communications.

We hadn’t any previous operational experience with digital communication between field instrumentation and a distributed control system (DCS). So, implementing digital communication between the field instrumentation and the DCS’s remote units (via a Profibus network) was an important challenge, and one that we successfully met.

For the SIS we rely on System 800xA High Integrity. This is a complete, scalable TÜV-certified IEC 61508- and IEC 61511-compliant SIS that spans the entire safety loop, including SIL-rated controllers, field input devices, I/O modules and field actuators.

For almost a year before the new plant went into operation we worked closely with ABB, enabling me to learn a great deal about how best to utilize System 800xA’s functionality.

Substantial benefits
The integrated 800xA safety and control system cut the hardware installation in half — we only needed one, not two, of everything, including one set of engineering tools. This saved time and money. Engineers and operators only had to be trained on a single system, which decreased training time and enhanced safety. In addition, while engineers used to set up, configure and calibrate instrumentation in the field, with System 800xA they can do all of this at their workstation.

The system is flexible and adaptable to changes, enabling us to easily introduce improvements. What I like most is the comprehensive information it offers as well as the speed of operation.

Its tools allow us to analyze conditions and tendencies that occur before a problem develops, furnishing extremely valuable information to the maintenance team and enabling us to make the right decisions. The new tools enhance the safety of the plant and the efficiency of the hydrogen peroxide production process by providing event lists and graphic trend displays. The engineering station offers a complete set of options for maintenance personnel, helping to adjust, calibrate, configure and bypass field instruments that are marked for verification or repair.

The system also notably reduces the time required for start up and shut down. The plant can be shut down in less than five minutes if needed. A single operator can complete a plant start up in less than 10 minutes.

Moreover, because of the system we’ve substantially speeded up a variety of activities such as operation startups and production regime changes. On average we’ve reduced time by 30 minutes per operation compared with actual values from identical activities performed in our adjacent A.O.A. I plant. Uptime has been optimal – there’ve been no plant shutdowns caused by problems in the control system.

The combined control and safety system gives peace of mind to our entire work team. We have the assurance of knowing that a safety system will kick in during an emergency.

Odel Protti is general manager of the A.O.A. I, A.O.A. II and acetic acid plants for Atanor, Rio Tercero, Argentina. E-mail him at [email protected]