Designing chemical processes and developing safe, efficient, and economical chemical plants is the work of process design engineering. Each design decision in a chemical process plant influences the performance and safety of the plant and also costs. This is because a design engineer performs hydraulic calculations and sizes equipment, which in turn can affect safety and increase the costs of a plant.
During process design, even the most experienced engineers are prone to making common mistakes in process design engineering, which may have varying effects, from equipment failures and inefficiencies in production to increased costs and delays in project completion. Chemical engineers should be aware of mistakes made during process design to avoid them and develop safe and efficient industrial processes.
- Incorrect Process Calculations and Material Balance
A process is made up of equipment and utility systems which in turn are designed based on the outcome of material balance and energy balance calculations. The outcome of these calculations determines size of equipment and utility systems and ultimately the success of a process. Errors in these calculations affect equipment specifications and performance of a plant.
How to avoid it: Design engineers should among other things, check process data to ensure the units are consistent, consider operating conditions of the plant and cross check calculations and finally critically review the design before it is documented.
- Lack of Consideration for Process Safety During Design
Process safety should not be considered at the end of design but should be incorporated at all stages of design.
Engineers may also ignore some safety studies that are required like HAZOP, PHA and sizing of Pressure Safety Valves (PSV).
How to avoid it: Integrate process safety in every phase of the design process. Conduct HAZOP studies, evaluate deviations, and protect systems. Ensure safety requirements meet related industry standards.
- Poor Equipment Sizing and Selection
When equipment is selected without regard to process requirements, plant efficiency can suffer and equipment can be oversized. Also, oversizing can increase capital expenditures.
Insufficient sizing of pumps and heat exchangers can lead to process upsets and instability. Separators and vessels that are too small can increase process upsets and decrease overall efficiency.
How to avoid it: Perform detailed engineering design calculations to determine flow, pressure, and temperature.
- Incomplete or Incorrect PFDs and P&IDs
PFDs and P&IDs are process and piping engineering documents. omissions of control valves, line specifications, instrumentation and proper connections of equipment can cause numerous process design engineering challenges during construction and commissioning.
Errors such as missing control valves, incorrect line specifications, incomplete instrumentation, and improper equipment connections can create significant challenges during construction and commissioning.
How to avoid it: Develop and implement uniform or standardized documentation procedures. Conduct interdisciplinary reviews of the documentation.
- Failing to Utilize Process Simulation and Optimization
With the constant changing nature of process technology and design requirements, the use of process simulation and optimization is commonplace in modern chemical plants. Engineers, who solely rely on manual calculations to design and analyze process equipment, can miss opportunities to improve a process.
A tool like Aspen HYSYS allows engineers to evaluate process conditions, equipment and various operating scenarios.
How to avoid it: Learn and understand process simulation software, and how to use the software to conduct what-if engineering analyses. Understand how the process of simulation results impact and supports engineering decisions.
- Not Considering Plant Operability and Maintenance
Designing a system in a technically correct manner may not necessarily result in efficient plant operation. There are several instances where accessibility for equipments maintenance and operation flexibility have not been considered. These may include adequate isolation for equipment maintenance, flexible alignment for operation in a staggered manner, etc. These may increase the cost of maintenance and cause unnecessary shut down for production.
How to avoid it: Design for the entire plant life cycle. Analyze operational requirements for start up and shut down, maintenance, and trouble shooting including emergency conditions.
- Lack of Practical Industrial Knowledge
Knowledge of basic theory is essential. However, applying these engineering principles to real industrial cases form the basis of process design. This practical understanding of industry is often lacking in fresh graduates, due to limited or no exposure to industrial design calculations and deliverables.
For chemical engineers in Gujarat, specifically in Vadodara, Bharuch, Ankleshwar, Dahej, Vapi and other areas, having practical process design skills can give them an edge in the competitive chemical industry.
How to avoid it: Thrive on industrially oriented training, projects, design calculations and case studies. Completing the process design online course will facilitate understanding of practical aspects and provide insights on integrating commercial viability into process design.
Conclusion
Avoiding mistakes in process design engineering is an amalgamation of a sound understanding of process design engineering fundamentals, focus and diligence, attention to detail, and practical experience. Process engineers require a sound understanding of process calculations and design, safety and key process equipment, PFDs and P&IDs, and simulations, to deliver quality engineering services.
Energy Learning based in Vadodara, Gujarat, offers process design training for chemical engineers. Through online and offline modules, practical process design projects and case studies, instruction and interaction by industry professionals, Energy Learning provides chemical and petrochemical process design training to aspiring process engineers.
