Optimize Distillation Column Design for Improved Reliability
in Operation and Maintenance
Karl Kolmetz, Dr. Wai Kiong Ng
Siang Hua Lee, Tau Yee Lim
Daniel R. Summers
Cyron Anthony Soyza
Phoenix Training & Development Centre, Johor Bahru, Malaysia
Prepared for,
Univeristi Tecknologi Malaysia
2nd Annual Conference on
Best Practices in Process Plant Management
Nikko Hotel, Kuala Lumpur, Malaysia
March 14-15, 2005
Abstract
A distillation tower design is normally made in two steps; a process design, followed by a mechanical design. The purpose of the process design is to calculate the required stream flows and number of required theoretical stages. Required steam flows could include reflux rate, side draws, and the heat duties (number of pump arounds and the condenser and reboiler). The purpose of the mechanical design is to select the tower internals, column diameter and height.
The process and mechanical designs can be completed very quickly utilizing “cook book” procedures that many Engineering Procurement and Construction (EPC) firms have established. Often the “cook book” designs can be optimized for improved profitability, operations and maintenance.
The best way to review profitability is the life cycle cost, which is the initial capital cost of the plant along with the first ten years operating and maintenance cost. The life cycle cost includes a reliability factor, which is very important in designing any process plant equipment. Improved reliability has a very large impact on return on investment (ROI).
Several factors should be considered when designing distillation equipment;
1. Correct distillation equipment for process conditions
2. Correct equipment selection for expected run length
3. Correct process control strategy to achieve stable operations
4. Fouling / corrosion / polymerization potential
5. Thermal stability, chemical stability and safety
6. Maintenance reliability, accessibility and simplicity of repair
7. Evaluation of the most cost effective solution for minimum life cycle cost
This review will include general distillation design guidelines applicable to any process along with specifics for the natural gas processing, refining, petrochemicals, and the oleo chemical’s industries.