Ottertail Power Company Big Stone Plant
Ottertail Power identified a need to improve the dust collection and handling system in the coal offloading system. The existing collection system consisted of multiple Ray Jet pulse type baghouse collection units with a total capacity of 134,000 SCFM. Dust was collected from the rotary car dumper (located inside a building) and two conveyors (also inside) as Powder River Basin coal was offloaded. The collected dust was transported by a screw conveyor system back to the coal hopper. The entire system was installed when the plant was constructed over 30 years prior. Performance of the system had degraded over the years and resulted in a persistent layer of dust throughout the building. This dust layer is extremely hazardous due to the explosive nature of Powder River Basin coal dust and created an unsafe and potentially dangerous condition inside the Rotary Coal Dumper building.
After performing a preliminary engineering study of available technologies and designs, OTPC selected a new low pressure dust collection system with a capacity of 150,000 SCFM. The new collection system design also incorporated containment to prevent dust from escaping capture. A pneumatic dust transport system was also installed to put the collected dust back into the system.
EAPC performed the preliminarily engineering study to evaluate available dust collection and handling technologies for Powder River Basin coal dust. Applicable codes were reviewed to determine requirements for a new system. A final report was submitted to OTPC which detailed available technologies and provided conceptual design and cost estimate for three of the most appropriate systems.
After reviewing the report and selecting a system, EAPC proceeded with the detailed design for a new low pressure dust collection system with pneumatic conveying. EAPC created technical bid specifications to ensure the new equipment met performance and OTPC requirements. After a system was selected, EAPC developed installation specification for OTPC to competitively bid the installation of the system. These specifications included electrical, civil, structural and mechanical items, such as instrument connections, power connections, equipment foundations, structural support bent, new MCC building, water piping and supports, etc.
EAPC also provided engineering support during the construction phase of the project.