Project management

Gas Turbine Air Inlet Filtration System Upgrade

Abstract
Gas Turbine Compressors at Generacion Mexicana Power Generation Plant have presented corrosion and erosion problems in the early stages of the air compressors that have been attributed to the performance of the existing air filtration system. The plant is located at the Golf Coast of Mexico in a marine coastal environment thatstimulates the ingestion of airborne salt that has been proven to be a major contributing factor in both decreased turbine performance and reduced engine lifetime. The compressors have presented corrosion pitting caused by sulfates and chlorides dissolved in the air, which are not being filtered by the current Duck Self-Cleaning filtration system.

Plant needs to replace the existing Duckpulse type filtration system with an improved “System1” filtration system, designed to capture all sizes of wet and dry salt particulate and to remove much of the captured salt from the intake. This will provide higher filtration efficiency and therefore a reduction of contaminants downstream of the filters.

The upgrade of the existing Duck system will require a major modification of thefilter house including the removal of the entire Duck equipment and the installation of a new system consisting of three stages of filtration, in a period of 12 days with a previous experience of a similar project that was executed in over14 days.

History and Technical Background

Generacion Mexicana Power Plant had a commercial operation date on January 2005 providing over 1,000 Megawattsto the Mexican power grid. After three years of operation, one of its four gas turbine compressors had a major failure caused by corrosion in the rotating blades. Root cause analysis showed that the existing filtration system, which main purpose is to protect a turbine from harmful airborne contaminants, was only preventive ingestion of particles, but not stopping dissolved contaminants such assalt, sulfur and several chlorides.
Damage is caused mainly in two ways:
1. Erosion, where relatively small particles and droplets impact compressor blades at high velocities.
2. Corrosive substances entering a turbine cause substantial damage in the blades.

A major failure of a compressor means the gas turbine unavailability of almost 30 days that represent tens of millions ofdollars in liquidated damages and repairs.
As part of a mitigation plan, a new filtration system (System1) was identified as the solution to the ingestion of contaminants due to its capability to capture wet and dry particles.

Project Goals and Objectives

Modification and upgrade of the existing Inlet Filter House of a gas turbine at the Generacion Mexicana Power Plant, replacing theexisting Duck Self-Cleaning filtration system with a new system that provides water removal capabilities and corrosion mitigation that will help improve the unit reliability and availability. Modification must be completed with an execution time of 12 days.

Deliverables

1. Removal of the existing Filtration System
2. Modification of the filter house structure to adapt for the newsystem
3. Installation of the new 3-stage Altair filtration System with wet and dry particles removal capabilities
4. Outage completion of 12 days or less

Milestones

1. Material reception by April 10th to confirm unit shutdown from customer
2. Unit shutdown on April 15th, 2010
3. Existing system removal by April 19th, 2010
4. Outage completion by April 26th, with an overallduration of less than 12 days

Technical requirements

- New system should provide a particle filtration similar to the existing Duck filtration system above 80% of particles size of 0.5 microns.
- System must have 2 stages of separators for water and salt removal
- Filtration will be divided in 2 different stages of Pre-filter and main fine filter
- Differential pressure...