Supercritical CO2 Power Cycle Preliminary Process Design

Project Synopsis

Develop process simulation models to aide in the development of preliminary process design information and the evaluation of several small-scale electric generation power cycles.

Project Summary

The client, a non-profit power research institute, contracted Process Engineering Associates, LLC (PROCESS) to provide engineering services for the preliminary process design and evaluation of several small-scale power cycles.  PROCESS’ scope was to provide due diligence to a preliminary third-party design configuration and develop heat and material balances for use by the client.

The power cycles are Brayton-cycle-based configurations utilizing a fuel gas stream and an oxygen-based, CO₂-rich oxidant stream.  The oxidant stream supports combustion of the fuel gas. The resulting high-temperature product stream is thermodynamically defined as a “supercritical” fluid (above the bulk component’s critical point, having neither pure vapor nor liquid properties).  The bulk supercritical stream is the working fluid that powers the turbine to produce electrical power.  This electrical power generation system is referred to as a “direct-fired supercritical CO₂ (sCO₂) power cycle”.

These oxy-fueled power cycle configurations are of a high interest as they have the real potential to be an economical choice for high-efficiency, low CO₂ emission power production.  In the power cycle developed in this work, CO₂, a greenhouse gas, is concentrated in a single stream and can be used for chemical production, enhanced oil recovery, or other uses.  There is growing interest in the commercialization of this technology within the power industry.

Four power cycle sizes are evaluated. Aspen Plus, a commercially available flowsheet simulator, was used for modeling the relevant thermodynamics of the power cycle process.  PROCESS used the software to identify deficiencies in the original concept, correct these deficiencies, and to develop the product CO₂ treating process (depressurization, catalytic oxidation, and drying in a molecular sieve).  At each step the client was involved in decision making to augment and modify the original configuration.

Heat and Material Balance (H&MB) tables and Process Flow Diagrams (PFDs) were developed for the new configuration at the four power levels.  Performance summaries were also generated that summarized in tabular form net power generation and presented a calculated result for the corresponding power cycle net plant heat rate (net output power divided by input energy of the natural gas).  Heat rate was calculated on a higher heating value (HHV) basis.  Equipment lists were also developed.  The project deliverables were used by the client to develop cost estimates for the individual power cycles.

Industry Type

Electrical Power Generation Research

Utilized Skills

• Process simulation modeling
• Process evaluation
• Process development support.