In response to a growing demand for a stable, cost-effective electric supply with low carbon emissions, the worldwide gas turbine industry is predicted to increase significantly in both the short and long term. Increased investment in the replacement of conventional aging infrastructure is driving such expansion. Natural gas has been the chosen fuel for most of today’s gas turbines due to its ample supply, ease of deployment, and low cost, while there is a growing trend to complement natural gas with hydrogen.
The gas turbine industry has progressed significantly over the last century, with some of the most significant developments being made in higher efficiency, fewer emissions, and enhanced production. Recent advancements have concentrated on designs and materials that enable faster starters, faster ramp-ups, higher efficiency, better, more reliable performance, and lower carbon emissions.
Combination cycle gas turbines are becoming more popular in terms of efficiency and pollution management. Although more expensive, they provide an excellent technique of capturing additional energy by extracting hot exhaust gases to generate steam and generate additional energy. The drive toward larger turbines is another recent design trend that is effectively enhancing output and efficiency. The cost per kilowatt decreases as the size grows. Larger turbines can also effectively replace coal or nuclear power plants. However, one major difficulty with larger turbines is that they require larger components that are more difficult to monitor, necessitating the use of extra sensors and analytics to avoid early failures or additional maintenance requirements.
Maintaining efficiency in the face of start/stop demands
Gas turbines will always be required because renewable energy sources such as wind and solar cannot produce energy 100% of the time. The problem, however, is to create flexible operations that can respond swiftly to changes in the grid. When more power is required, the industry typically looks to gas turbines to fill the shortfall. The constant requirement to shut down and restart engines brings its own set of issues.
Engineers must be mindful of increased deterioration of seals and bearings, as well as a greater risk of blade flutter and fatigue damage, as they continue to upgrade older models to increase output and create designs that accommodate faster ramp-up, increased cyclic operation, and longer intervals of operation at low partial loads. Temperature, fuel flow, fuel pressure, airflow, air pressure, exhaust gas flow, fuel quality, and exhaust gas particles are all indicators that an engine is not operating efficiently and that maintenance is required.
Increasing gas turbine efficiency in harsh conditions
Despite the industry’s emphasis on efficiency, most gas turbines today are only approximately 40% efficient, which implies that 60% of the heat generated is squandered when employing a simple cycle operation that relies solely on a gas turbine. In combined cycle operations, a steam turbine converts waste heat from gas turbines into additional energy. The end effect is increased efficiency but at a significant cost.
The conflict at the heart of efficiency is a drive to run hotter. A gas turbine operates more efficiently and provides more output as the temperature rises due to the thermodynamics of the operation. On the other hand, building a turbine with a higher firing temperature and efficiency is extremely challenging since few materials can withstand such high temperatures without melting.
In response to these concerns, significant modifications have been made to gas turbine components:
- Extreme temperature tolerance and durability superalloys
- Specialized seals and material solutions for higher temperatures have been identified as crucial to achieving combined cycle gas turbine efficiency levels of 65 percent.
- Thermal coatings with increased durability are used to protect turbine parts from heat.
- Sensors that monitor turbine performance and component life are tough enough to withstand extreme temperatures.
- Turbine inlet cooling systems lower the temperature of the intake air to compensate for lower power production.
Changing activities to make better use of hydrogen
Although natural gas has long been a favored fuel for gas turbines, the industry is undergoing a large-scale decarbonization shift. The main disadvantage of natural gas is that it is a fossil fuel that emits numerous emissions; including carbon dioxide, when burned. As more businesses implement aggressive green programs, interest in cleaner fuel sources such as hydrogen; which when burned produces just water as a byproduct, is growing.
As a result, several major power equipment manufacturers are developing gas turbines; that can run on a high-hydrogen-volume fuel mix of natural gas and hydrogen.
Advantages of Hydrogen
Hydrogen, the most abundant and lightest element, is an appealing fuel source for a variety of reasons:
- It is odorless and non-toxic, and it has the largest energy content by weight of any common fuel; allowing it to be employed as an energy carrier in a variety of applications ranging from power production to transportation and industrial.
- Its production technologies are gaining technical maturity and economies of scale.
Disadvantages of Hydrogen
Concurrently, hydrogen has several drawbacks. There are several safety concerns, including:
- It is difficult to handle since it burns violently and has the potential to be explosive.
- Highly combustible range that only requires static electricity to ignite.
- NOx, flashback, and combustion pressure variation
- Flashback is a phenomenon in which flames inside the combustor travel up the incoming fuel; and leave the chamber due to the particular properties of hydrogen and the mixing of hydrogen with air.
- Materials with greater melting temperatures must be discovered since it burns faster and hotter.
- Because it is not as dense as natural gas, existing fuel lines will need to be modified to accommodate it.
- Because hydrogen molecules are so tiny, they can pass through most metals.
- To avoid hydrogen diffusion, newer, softer seals and/or specific metals must be used.
- Problems with storage, whether as a gas requiring high-pressure tanks or as a liquid requiring cryogenic temperatures.
Condition monitoring and predictive maintenance
Gas turbines are only as good as their constituent parts. Today, there is a better knowledge of the importance of maintaining components in good working order and monitoring their performance in order to do maintenance before catastrophic failures occur. However, it is not just about avoiding breakdowns and scheduling maintenance during off-peak hours. As a result, there has been a paradigm shift from preventative to predictive maintenance. Condition monitoring and predictive maintenance are important.
Instead of scheduling maintenance at predetermined times regardless of the remaining component life; today’s astute maintenance managers use sophisticated sensors and analytics. To accurately measure service life and predict when worn components or contaminated fluids are at risk of impairing turbine performance.
Gas turbine Control System
Gas turbine control system monitors and safeguards gas turbine operation. In recent years, significant progress has been achieved in the development of more advanced remote condition monitoring and problem diagnostic systems. IS215UCVDH1A, and IS215UCVDH2A are some examples of gas turbine control parts by GE.