MSW-Fired Electrical Generation Unit FEL-2 Process Design

Project Synopsis

Project Summary

The client is developing a project to pyrolyze municipal solid waste (MSW) at an existing landfill in the southeastern U.S. The basis of the technology is an externally-heated – no air or oxygen is intentionally fed to the unit – pyrolyzer developed by the client. The project is based on the use of three individual pyrolysis units. Each pyrolyzer unit consumes a nominal one third of the MSW. The pyrolyzer units produce a tar and particulate-laden synthesis gas that can be cleaned and used as a fuel gas or as a precursor to chemicals production. In this project, the clean synthesis gas is used as a fuel.

The objective of the work conducted by Process Engineering Associates, LLC (PROCESS) was to develop an FEL-2 Process Design with a +/- 50% Total Installed Cost (TIC) Estimate for an MSW-derived-gas to electrical power generation facility. Make Gas from the client’s pyrolyzer units will be cleaned in a tar removal system and combusted as Product Gas in a packaged boiler. Steam generated in this Product Gas Boiler will be expanded in a non-reheat steam turbine generator set. A cooling tower will be used to provide cooling water to condense the steam turbine exhaust. Tar and combustible particulates removed in the tar removal system is combusted in a separate Tar Boiler in order to generate additional steam and subsequent electrical power. Char removed from the pyrolzer and cyclone upstream of the tar removal step will be sent to the landfill for disposal.

Specific project tasks included:

• Process Design Basis preparation involved the development of the baseline information that governed subsequent process design tasks. Data in this basis included both PROCESS’ and the tar removal technology vendor’s technical boundary limits (TBLs).
• Mass and Energy Balance (M&EB) preparation involved the development of a M&EB for the gas combustion and power generation cycle (Rankine). This included process stream flow rates, compositions, temperatures, pressures, and physical/chemical properties. This involved set-up of a process simulation model in CHEMCAD software. A corresponding Process Flow Diagram (PFD) was prepared as well. The PFD depicted the primary unit operations of the power generating facility.
• Major Equipment List development involved equipment sizing and the preparation of duty specifications in order to solicit vendor-specific equipment performance/size and budgetary quote information from Original Equipment Manufacturers (OEMs). The amount of detail included in the equipment specification was such that a detail engineering firm could continue with design during the FEL-3 phase of work. Major equipment included, but was not limited to pyrolyzer, cyclone, tar removal units, boilers, steam turbine, cooling tower, etc.
• Preliminary (e.g., 60% complete) Piping & Instrumentation Diagrams (P&IDs) we developed. The P&IDs depicted the primary unit operations, process streams, as well as the primary instrumentation and controls. Sufficient detail was included such that the P&IDs could be used to initiate the FEL-3 design phase.
• A HAZOP meeting was conducted on all process equipment excluding MSW preparation and pyrolyzer operation. The HAZOP was facilitated by PROCESS at the client site and was based on the P&IDs produced and described above.
• A TIC Estimate of +/-50 percent (excluding MSW preparation, pyrolyzer equipment, and tar removal system TBL) was generated for the facility. The TIC Estimate takes the form of a factored cost estimate with the bulk of the process equipment costs obtained from OEM input. Some equipment was cost estimated by PROCESS via ICARUS software. Cost data obtained via ICARUS was based on the equipment specifications generated during the process design.

Industry Type

Utilized Skills

• Detailed process design
• ROM cost estimating.