Gas turbines are a common sight in distributed energy applications. Driven by the ever-increasing need for higher peak loads in utilities, facility operators have found it necessary to ensure peak performance of gas turbines. One way of ensuring efficient performance of the gas turbine is regular maintenance. This article relooks into industrial gas turbine maintenance. Are you wondering what gas turbine maintenance entails? You have all the answers in the following sections.
Crucial Gas Turbine system Components
During maintenance, the technicians check every part of the gas turbine system. However, there are certain major components that demand special attention. Here is a list of some of them:
- Air intake
- Exhaust chimney
- Electric generator
Conditions within the Gas Turbine
The gas turbine may have a simple operating principle, but the equipment comprises of highly specialized components. In addition, these components have extremely fine tolerance of operation. There is an even bigger challenge within the turbine. GT components operate under extremely high temperatures. Today, we have turbines operating at inlet temperatures of 1300 °C and above. This is coupled by the presence of corrosive gases and elevated stress levels. Maintenance is about fighting the challenges created by this harsh environment.
Filtering Inlet Air-Important Maintenance Exercise
Have you ever noted a filtering unit in the air intake part of the gas turbine system? Filtering intake air is an essential form of preventive maintenance because of the danger posed by particles and other foreign matter. If left unattended, the particles will build up, eventually reducing turbine efficiency. A nut could find its way into the intake duct, albeit accidentally. Maybe you are wondering what particles could be in intake air. If a facility is along the coast, most of these particles will be sodium chloride particles. Salt is a corrosive material that could damage turbine blades. Salt can also attract dirt thus lowering turbine efficiency.
Regular GT Inspection
Technicians collect system performance data during these inspections. Examples of variables in this case include temperature, pressure, and vibration. The baseline performance data from the original equipment manufacturer (OEM) comes in handy here. Technicians compare the baseline data and the collected data. Any deviations are noted and lined up for investigations during the next shutdown maintenance session. These anomalies are assessed and depending on their severity, prioritized for repairs . The importance of this is to maximize the availability of the turbine. This is also an ideal opportunity to add any performance-enhancing upgrades.
Extra Check on Hot GT Sections
Turbine components subjected to extremely high temperatures require special attention during inspection. The point of taking a closer look is that overheating can be a serious problem. A borescope would be enough for an experienced technician to determine common overheating problems. At ARANER, we however prefer to make it thorough by using modern approaches, such as thermography method. Some popular tools for conducting these tests are infrared camera and imaging camera. What next after a problem is detected?
Gas Turbine Repairs
While checking for problems in turbines is challenging, an equally daunting task is how to do repairs. The conventional repair sector is having it rough because most modern components are advanced technologically. Without modern materials, inspection methods and repair techniques, one cannot do much. Take for instance the cowl caps, fuel nozzles and other combustion components. Repairing a component must be preceded by advanced dimensional inspection. Nondestructive inspection must also be done before welding any component. Owing to the high temperatures in a turbine, the need for advanced maintenance and repair methods cannot be overemphasized. Refurbishment methods to deal with mechanical stresses and high operating temperatures include:
- Removal of old coating and application of a new one
- Welding to rebuild geometry
- Heat treatment to rejuvenate material condition
- Change in design and materials (advanced procedures)
Talking of change in design, the case of the 25MW SGT-600 gas turbine from Siemens (see Fig 1) comes to mind. The model has undergone numerous modifications to suit the dynamic market demands on various aspects of the gas turbine.
Fig 1: The SGT-600 Gas Turbine
ARANER performs several modern procedures to increase the highest turbine efficiency; or to counteract the effects of turbine degradation. A popular power augmentation method, Turbine Inlet Air Cooling (TIAC), could be a perfect addition to your system in tandem with regular maintenance.
Benefits of GT Maintenance
The aim of proper gas turbine maintenance is generally to enhance the productivity of the facility for the long-term. Following the laid down maintenance and repair procedures will bring the following benefits:
- Increased system efficiency
- Extended gas turbine life-cycle
- Reduced maintenance cost
- Increased availability of gas turbine
- Increased reliability of equipment
There is a reason gas turbine manufacturers take development and improvement of their products so seriously. Profitability and competitiveness in the industry mean that every facility must operate in the most efficient manner. ARANER is a key player in the GT efficiency efforts. The company’s TIAC technology is being used worldwide as a power augmentation method. During your next shutdown for gas turbine maintenance, you might want to consider inviting the experts for analysis of feasibility of this solution.