Front end engineering design study to define the technologies and unit operations for a process required to remove impurities from a biomass syngas intermediate stream and purify/separate the desired final products.
GAS TO LIQUIDS (FISCHER-TROPSCH) FACILITY FEASIBILITY STUDY
The client possesses a proprietary plasma arc gasification technology that they plan to use to generate synthesis gas from biomass. The synthesis gas would then be processed in a Fischer-Tropsch type facility to produce ethanol and higher alcohols. The client contracted Process Engineering Associates, LLC (PROCESS) to define the technologies and unit operations required to remove impurities from the syngas and to purify and separate the desired products. Project tasks included:
- Preliminary process design basis development
- Technical and economic evaluation of process alternatives
- Final process design basis development
For the preliminary design basis development, PROCESS collected information from the client for their plasma gasifier and Fischer-Tropsch reactors to define the input stream, syngas characteristics, gas cleanliness requirements, reaction products, and the product specifications. Preliminary calculations were performed as necessary to validate the resulting preliminary mass balance. These calculations revealed significant inconsistencies between the various data sources. Several data collection and calculation iterations were required to arrive at a reasonably consistent basis for subsequent project tasks.
For the technical and economic evaluations, the preliminary process design basis was used to determine the sequence of unit operations required to achieve the required process goals. Alternative technologies for the various process steps were identified and evaluated for technical feasibility for this project. Alternatives that were deemed technically feasible were further evaluated on an economic basis to determine which alternative should be incorporated into the system design. The economic evaluation included a preliminary capital and operating cost estimate for each alternative.
Evaluations were performed for gas cooling, heat recovery, particulate removal, acid gas removal, carbonyl sulfide removal, gas polishing, water-gas shift, and for the intermediate and final product stream separation, purification, and recovery steps. Recommendations were then made regarding the logical sequence of unit operations to achieve the process goals.
For the final process design basis development, PROCESS assimilated the results and recommendations of the alternatives technical and economic evaluations into the original design basis. The preliminary process design basis flow, composition, cleanliness, and product streams were refined to reflect expected values based on use of the recommended unit operations. Calculations were again performed to arrive at a preliminary mass balance for the system to validate the overall system performance. This final design basis will form the basis for all subsequent tasks during detailed process engineering for the project.
PROCESS' licensed commercial process simulation software CHEMCAD was used as required in the development of the mass balance and for the technical evaluation of unit operations as applicable.
The project was difficult in the sense that a very limited amount of (often conflicting) data and existing process information for a very unique processing facility had to be analyzed and developed through a series of iterations with the client into a potentially technically-feasible facility. The client will take the information from this project and decide if a process design of the facility is warranted.
- Syngas / Synfuels / Gas To Liquids (GTL)
- Alternative Fuels
- Design basis development
- Front end engineering design study (FEED study)
- Process technical and economic evaluation
- Process simulation
- Heat & Material Balances
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