Challenge

A utility client needed to plan for an outage in their supercritical generating station. They had identified systems that were in need of replacement, including a stainless steel flue gas desulfurization (FGD) spray header system that needed to be replaced due to corrosion and failure in the existing header material, a steam chest with a substantial deformation that was resulting in operational issues with the control valves, and a degraded coal burner that was causing forced outages. Additionally, a major overhaul of the turbine of one of the units in the generating stations was due for routine service.

Solution

Valdes worked with the client and other construction and technical services partners to inspect the existing conditions of the unit's FGD spray header system, determine the extent of the corrosion and failures, and prepare a design for the replacement of the spray header system. The new design used fiberglass reinforced plastic (FRP) to mitigate future corrosion and planned for additional stiffeners to be installed to the absorber shell since the weight of the new FRP headers exceeded that of the current headers. Valdes worked with the client and other construction and technical services partners to develop a restraint plan for the installation of the new steam chest. Temporary pipe and equipment were installed, main stop valves and control valves were removed and sent to the shop for inspection and repairs, steam chest inlet and outlet lines were cut, the existing steam chest was removed and machine preparation was conducted for existing lines before the new steam chest was installed and the connections were completed. Valdes led the development of the plan for and oversaw the disassembly, inspection and repair of the unit's turbine and generator by another service provider on behalf of the utility, which included sending high-pressure-intermediate-pressure (HPIP) rotors offsite for inspection and repair. Valdes worked with the utility's plant engineering staff to determine the scope for replacing the burner and oversaw the disassembly and removal of the burner and subsequent installation of its replacement.

Impact

Despite delays due to significant weather, Valdes worked with its partners to complete the installation of the FGD spray header. The installation was successfully completed on schedule. Valdes prepared for the installation of the new steam chest and completed the project one week ahead of schedule, solving the operational issues the client was experiencing. The plan and oversight provided by Valdes will bring the burner replacement project to completion on time and ultimately reduce the risk of forced outages and burner fires for the utility. Although considered regular maintenance every ten years, Valdes' planning and oversight made it possible to conclude with disassembly, inspection and repair of the turbine one week ahead of schedule. All of these projects were completed on or below approved budgets.

Services

Laser Scanning & Surveying

Project Management