Distributed Control System (DCS) providers identify as a best practice pursuing a standardized approach to the configuration and control of Related Units within batch processes.
Given that no two processes are alike, however, there are tremendous benefits to utilizing established standards and best practices that provide a consistent framework for the creation of the fundamental building blocks of the Distributed Control System (DCS) – the Unit.
In processing, a Unit is responsible for a specific action within the Master Recipe, such as heating, cooling, adding, blending, or separating material. Most batch processes consist of a “train” of such Units, where material is introduced in the first Unit and passed from Unit to Unit.
The DCS must, therefore, be designed based on defined standard methods that play a key role in simplifying the formation, organization, and even software programming of the Units within the DCS.
This is where the concept of Unit Relativity comes into play. The goal is to design a fixed sequence for one Unit that can be executed on any number of similar Units. To accomplish this, there must be a consistent organization of relative Units with the same structure, sequence of actions, variables, and naming conventions.
The concept of Unit Relative Operations was first introduced to the process control industry by EMC Controls with the D/3 DCS in 1982. Since then, more vendors have begun to offer support for this approach.
According to Robert M. Ard, Senior Advisor at Valmet, the company’s D3 Control System has built-in support for Unit-based control. Valmet is a leading global developer and supplier of process technologies, automation, and services for the pulp, paper, energy, marine, and other process industries. In January of 2023, the company completed the acquisition of the popular D3 Control System from NovaTech Automation.
D3’s Phase logic and the company’s proprietary software, FlexBatch®, control the Units required to make the batch. To achieve Unit Relativity, each similar Unit in the D3 Control System is configured with identical contiguous structures, using the same types of devices, and in the same sequence of operations.
By applying Unit Relativity, DCS providers can greatly reduce the lifecycle costs of the application and help ensure uniform controls across all similar units. By applying uniform controls across all related units, DCS providers can ensure a consistent and efficient process that aligns perfectly with ANSI/ISA88 standards.
For more information, visit www.valmet.com or call 410-753-8300.