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ISG RIVERDALE BOF GAS COOLER REPLACEMENT
On June 28,2004 the BOF Shop at ISG Steel Company’s Riverdale Illinois Facility experienced the unexpected loss of their primary gas cooler. The cooler collapsed forcing the emergency shut down of steelmaking operations. ATSI, Inc. was contacted and requested to immediately report to the facility to assess the damages. ATSI, Inc. was on site within an hour and in conjunction with ISG personnel, determined that the collapsed cooler was beyond repair and should be completely demolished.
Photo #1 Demolition of collapsed Gas Cooler in progress Preliminary estimates predicted that the facility would be down for approximately 32 days while a new gas cooler was fabricated and installed. ATSI, Inc. understood that this extended unplanned loss of production, placed an undue hardship upon one of our most preferred clients. In response, working with Riverdale Plant Engineering team members ATSI, Inc. began discussions for a possible solution. By 7:00 PM that day (June 28 2004) the team had developed a PRELIMINARY plan to get the facility back in operation. The plan involved the construction of a temporary by-pass. The by pass would simulate a gas cooler via the installation of atomizing water spray nozzles in the existing horizontal ductwork between the BOF and the Precipitator. It was determined that the atomizing spray nozzles could be made to effectively cool the gas within a relatively short section of ductwork, at normal operating velocity predicting little or no accumulation within the horizontal duct. The plan would allow steelmaking operations to resume and continue during demolition and construction of the new cooler, at least theoretically.
Figure #1 Gas Cooler Temporary By-Pass
Preliminary estimates predicted that the facility would be down for approximately 32 days while a new gas cooler was fabricated and installed. Within 5 days, the by-pass was constructed and limited production resumed.  Photo #2 Installation of Spray Nozzles in Existing Ductwork
Photo #3 Temporary By-Pass Spray Header & Nozzle installation complete The performance of the temporary by-pass surpassed all expectations, shop emissions and stack emissions were as good as when the gas cooler was in operation. By the second day of operating on the temporary by-pass the facility increased to full production. The temporary repair allowed ISG to continue production eventually regaining the 5 days lost during the installation of the temporary by-pass. Simultaneously the design, erection planning, and fabrication of a replacement gas cooler were in progress. To accelerate installation the general contractor suggested that the replacement cooler be fabricated and shipped as four main segments consisting of top segment, 2 mid segments, and a bottom segment. Each segment was to be fabricated in the desired erection sequence and shipped to the site (see photo 6).
Photo #4 Gas Cooler Replacement Top Segment delivery to site
Photo #5 Top Segment on the road
Photo #6 Bottom Segment ready for shipment
The fabrication and installation of the new design gas cooler was completed in 28 days 5 days ahead of the preliminary estimates made on the day of the collapse.
Photo #7 Gas Cooler waiting for final mid-segment to be installed
Once the replacement gas cooler was installed and made ready for final connection, the entire system was taken out of service. The temporary by-pass was removed as well as the sections of ductwork, which functioned as the simulated cooler. It was felt that because those sections of ductwork were subjected to large temperature variations during the temporary operation that their replacement would ensure trouble free operation in the future.
Photo #8 Existing ductwork sections used as temporary gas cooler being removed
Photo #9 Existing ductwork sections used as temporary gas cooler being removed In spite of the unexpected loss of a primary piece of process equipment, which predictable would have normally resulted in a month long shut down, ISG experienced no loss of production. The temporary by-pass concept combined with the concentrated effort of ATSI, Inc. ISG Plant Engineering and local fabrication and construction companies, resulted in an extremely successful project. The gas cooler continues in operation one year later without incident or modification. Just another chapter in “life at ATSI, Inc.”.
ATSI: Buffalo, Pittsburgh and Chicago's premier consulting engineering firm. We employ the industries finest HVAC, structural, civil, electrical, instrumentation & controls and mechanical consulting engineers. We also specialize in facility construction services including automotive facility construction and blast furnace construction. We are your expert choice for traditional and custom consulting engineering services.
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