John Vincent Ergina
Chief Technology Engineer - LNG & Gas Processing
Sr. Process Engineer – LNG & Gas Processing
09:15 - 09:45
Thursday, 19 September 2019
T3.7 Impact of Thermodynamic Package Selection on Lean LNG Plant Design
Process simulation is the central tool for process engineering design. The efficacy of such models can only be truly verified with operational data of the designed plant. One of the most important elements of process simulation is the selection of thermodynamic packages. These packages are comprised of equations of state, pure component coefficients, and binary interaction coefficients. Thus, thermodynamic package selection is paramount for the facility to be modelled accurately especially near the critical region – which is difficult to replicate in simulation. This has garnered attention on recent LNG designs with lean gas feeds, which push portions of the process close to critical conditions. Producing on-spec LNG is more difficult with leaner gas because operation near critical conditions decreases the effectiveness of the heavy hydrocarbon removal system. Out-of-the-box thermodynamic packages from simulator programs are not adequate for conducting performance guarantee simulations.
Commercially, the selection of thermodynamic packages will not only affect the design and cost of equipment, but could determine whether the process will even work. It also affects the process efficiency in terms of refrigeration power and LNG production. Both of these are used in financial models and inaccurate results can make or break the project. Furthermore, new LNG technologies, which have not been commercialized for large scale LNG facilities, are being proposed on recent projects which adds technical risks. Therefore, properly selecting the best model early in design is of great importance. Achieving on-spec product at name-plate capacity is the focus and relying on typical industry practice with respect to thermodynamic packages might be incapable of achieving such goals.
In this paper three different thermodynamic packages are reviewed: modified Benedict Webb Rubin, typical industry practice (Peng-Robinson with enthalpy correction), and standard out-of-the-box Peng-Robinson will be compared against operational data of a reference plant.