Case Study

Blackstone Energy Project – Blackstone

Case Study

Blackstone Energy Project – Blackstone

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Dynegy (now Vistra Energy) contacted Galebreaker because they were having shaft and bearing problems between the fan and gear reducer on their windward side.

The Challenge

Blackstone ANP is a 250MW SPX unit based near Boston Massachusetts. During the summer months the air inlet to Gas Turbine #1 experiences air temperatures approximately 2°F warmer than the air inlet to Gas Turbine #2, which is immediately southwest of unit #1. Maintaining a lower air inlet temperature is important to the efficiency of the plant and it’s ability to produce electricity. Currently, a fogging system is installed on the air inlet of GT #1. When utilized, this system injects a mist of demineralized water that lowers the air temperature in the inlet, thereby increasing the efficiency of Unit #1. Though this fogging system works well, the cost of operating the system is prohibitive, so that it is only operated at times when it is economically beneficial. Therefore, much of the time in summer, unit #1 is running at a lower efficiency than unit #2. Along with these challenges, other wind related issues were causing gear reducer failures which in turn led to further inefficiencies at the plant. The fogging system, though costly, was the most effective solution.

The Solution

In 2015 and 2016 the goal for ANP Blackstone was to uncover any actions that could be taken to prevent warm air from elsewhere in the plant from entering the air inlet of Gas Turbine #1 as well as find a solution to the wind related issues of gear reducer failures. After an extensive wind related CFD study and consultation with Gary Mirsky, Galebreaker were commissioned in 2017 to install their patented Wind Screens on the ACC unit. No. 5 screens were installed on the South side and No. 3 Wind Screens installed on the East side – a total of 550sqm (approx. 6,000sqft). Galebreaker also performed an Engineering Structural & Verification Analysis ACC unit to determine its capability to accept thew wind loads for the Screens. All passed with flying colours!

The Benefits

The Galebreaker Wind Screens have been a success for Dynegy and the ANP Blackstone plant. The gear reducer failures have been solved by reducing the impact of wind vibration. Whilst fogging remains the most effective way of reducing ambient air temperature entering the fans, the Wind Screens have helped with the re-circulation and interference issues that the ACC was seeing during hot windy days. After reviewing the thermal performance assessment it was clear that the Screens have demonstrated an improvement in reliability, a reduction in back pressure, less thermal interference and a gain in performance.

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