Wood develops first of a kind method and saves power client millions

Florida is the second largest producer of electricity in the United States, but as the third-largest electricity consumer in the nation, does not produce enough electricity to meet its own power requirements, according to the U.S. Energy Information Administration. The residential sector consumes more than half of its electricity, and as the state's population continues to grow, demand is expected to increase. Florida also has a high number of registered electric vehicles, second only to California, and there are more than 2,300 public-access electric vehicle charging stations across the state.

Natural gas fueled around 75% of Florida’s total electricity generation in 2020. To keep clean-burning natural gas units at power plants operating reliably and efficiently, they require ongoing maintenance like the replacement of Heat Recovery Steam Generators (HRSG) Low Pressure (LP) economizer and evaporative sections. HRSGs convert high heat from turbine exhaust gases into the power that drives the steam turbines, producing less carbon emissions than alternative equipment.

Addressing the challenge

The typical process for replacing HRSG LP evaporator and economizer sections involves accessing the components from above the HRSG. This not only requires heavy lift cranes, with a weight capacity of at least 800 tons, but existing steam drums and riser tubes which make access difficult. As such, this process often results in longer down times and higher costs for power generators.

When preparing to replace 14 Foster Wheeler HRSG units for a client in Florida, Wood developed and applied a new innovative method to provide significant cost savings to the client and ultimately benefitting its rate-paying business and residential customers. Wood’s team developed a horizontal trolley rigging system for the HRSG retrofits. This first of its kind method enabled access from the side of the HRSG casing to minimize the removal of existing equipment and heavy crane requirements.

Utilizing this horizontal trolley system, the team was able to reduce the radius and the boom point elevation of the heavy lift crane, and therefore, reduce the required crane capacity from 800 tons to 500 tons, saving the client considerable cost. This innovative method also reduced total down time of the units by over 50%.

The design, supply and install nature of this awarded contract allowed for the early constructability reviews between the design and the installation teams to engineer and implement the trolley system. The temporary monorail beams and the trolleys were modeled in advance by the design team to ensure the plan’s feasibility and built into the design.

Delivering a full-service solution

Wood’s experienced integrated project team executed the full contract scope to design, supply and install our engineered products, relieving the client of any issues or gaps that could have occurred from using a designer or supplier and a separate installation contractor. While Wood’s integrated team was responsible from start to finish of this turn-key project, the installation portion also provided construction employment to the local labor force and to local vendors in Florida that supplied construction equipment, tools, and materials.

The engineering and construction plan saved the client substantial time and money to the tune of an estimated $500,000 USD per section per HRSG. This equated to a savings of approximately $7 million USD for the LP economizer sections. The team also used this method to replace the 14 LP evaporative sections on the same units, performed during earlier unit outages, ultimately saving the client an estimated $14 million USD in comparison to the traditional method. Since the implementation of this first of its kind industry methodology, it has been used by other contractors to save utilities and rate paying customers across the industry.