Published on 20 Apr 2019 by Arun Patel
See The Role of Inherently Safer Design Concepts in Process Risk Management for more information related to Consideration for Inherently Safer Process Options.
The search for inherently safer process options must begin early in the process life cycle, and never stop. The greatest potential opportunities for impacting process design occur early in the invention and development of processes. As stated by the National Research Council, "Few basic decisions affect the hazard potential of a facility more than the initial choice of technology." Early in development there is a great deal of freedom in the selection of chemistry, solvents, raw materials, process intermediates, unit operations, facility location, and other process parameters. As the process moves through its life cycle, it becomes more difficult and expensive to change the basic process.
It is never too late to consider inherently safer alternatives. Major enhancements to the inherent safety of facilities which have been operating for many years have been reported over the years for lessons learning. Below table is a summary of some of the key questions that should be asked at various stages in the development of a facility design.
Key Questions and Decisions
What product?What capacity?
Market researchResearch and Development new product ideas
|Process Synthesis Route
How to make the product?
What route?What reactions, materials, starting points?
Research and Development
Known synthesis routes andtechniques
||Basic unit operation selection with flow rates, conversion factors, temperatures, pressures) solvents and catalyst selection
||Process synthesis route laboratory and pilot scale trials
Knowledge of existing processes
||Batch vs. Continuous operation
Detailed unit operations selection
Control and operation philosophy
|Information above plus process engineering design principles and experience|
|Process Conceptual Design||Equipment selection and sizing
Inventory of process
Single vs. Multiple trains
Overdesign and flexibility
Recycles and buffer capacities
Instrumentation and control
Location of facility
Preliminary facility layout
Materials of construction
|As above plus equipment suppliers data, raw materials data, company design procedures and requirements|
|Process Detailed Design
||Detailed specification based on concept design
Minimize number of possible leak paths
Make facility "friendly" to control, operate, and maintain
Avoid or simplify hazardous activities such as sampling, loading and unloading
|Process conceptual design and codes/standards and procedures Experience on past projects/designs
To be most effective, an inherent safety program should have the objective of creating an awareness of inherent safety in a broad range of chemists and engineers involved in the development of products and processes throughout an organization. The inherently safer way of doing things should become a way of thinking and working. Perhaps the critical moment in the life of any idea occurs immediately after the idea springs into a person's head. Does he or she pursue the idea, file it away for further thought, discuss it with a colleague, or just forget it as being of no further interest? If everyone in the organization understands that inherently safer products and processes are valued and desired, it is much more likely that ideas with the potential to develop into inherently safer systems will survive this critical moment, and will grow and mature.
Upper management in an organization should have regular communications with the team to emphasize the important subject of inherent safety & design to ensure technical professionals share ideas and hold frequent discussions on safer design.
See next part for Inherent Safety Trade-offs for more information related to Consideration for Inherently Safer Process Options.