(6c) Inside-out Design Approach for Optimizing Distillation Design

This presentation provides a compilation of recent successful case studies, from various processing (refining/upgrading, high purity petrochemical, air separation) areas, further demonstrating the economic value to designers and operators in having equipment (eg. heat exchange and tower internals) experts involved in the initial development of a process design.

The basis for the inside-out approach, as the name implies, is to start the design at the heart of the separation process, the distillation column, and work outwards to the supporting equipment

The significant process and mechanical benefits captured from an inside-out approach (process and mechanical,) far outweigh the additional investment in time.

Process benefits come from capturing energy efficiencies, and/or increasing product yield through

1. Embedding detailed equipment characteristics into process simulation (vs. typical rules of thumb)

2. Flowsheet topology improvements

3. Column staging optimization

Mechanical benefits come from incorporating the appropriate considerations by

1. Using specifications developed from operating, construction and shutdown experience

2. Modularization to simply field work

These process and mechanical benefits result by following the inside-out approach (detailed Figures provided in presentation). Once the initial economic objectives, cycle screening and simulation are developed, the steps highlighted in green use the detailed input from an equipment expert (ideally an experienced equipment vendor expert) to build the equipment scope from the inside (distillation process) out. The process evaluation continues to ensure no equipment envelopes are violated with any necessary iterations performed.

One of the keys to making this approach successful is finding an available in-house expert or a vendor with a long term, lifecycle approach that is willing to provide the necessary scoping support. The following examples indicate the search for an equipment expert to assist in the initial design phase is well worth the effort.

Inside-Out Design Case Studies provided in Presentation

a) A&V Unit Grassroots design

b) Vacuum Column designed for phased production requirements

c) C3 (propane/propylene) Splitter grassroots design

d) Air Separation Unit

The inside out approach provides a successful methodology for a designer to follow to provide an optimized design by incorporating appropriate equipment characteristics into the design. The examples in the paper, reinforce the value of the inside out approach while highlighting the value from engaging external equipment expert into the early stages of the design process. Also, nearly any process from heavy oil upgrading to polymer feed conditioning can benefit from the inside out approach.