The global energy markets are changing, which may lead to new operating profiles with higher flexibility requirements for many fossil power plants. To help address a wide range of changing operational requirements, Siemens Energy has developed and continues to evolve Flex-Power Services™.
The Flex-Power Services™ portfolio includes products and solutions as well as studies and assessments to help adapt to changing operational requirements. Siemens Energy develops solutions to help enhance operational flexibility of power plants and its key components.
Flex-Power Services™ can be provided as a retrofit for the Siemens Energy service fleet and often be combined with other modernizations. Implementing these state-of-the-art features can help to increase power plant flexibility and retain or improve plant competitiveness in the changing energy market.
Products and solutions supporting Power on Demand are intended to enhance Start & Stop Performance and can include upgrades designed to:
A shortened start-up or shutdown time may not only increase flexibility, but also support a reduction of fuel consumption and associated emissions in these operating conditions.
Solution
Some combined cycle power plants which were originally built as base load plants are now operating as peak load plants or as cycling plants with frequent start-ups. Hot starts after an overnight shutdown may need to be performed fast, using predictable and reliable measures to provide a high dispatch ability and in-market availability.
Hot Start on the Fly is an innovative upgrade for combined cycle power plants designed to significantly reduce the plant’s hot start times down to a plant specific value of - in many cases - approx. 30 minutes.
Potential benefits
Depending on the operational limitations and requirements of your power plant, the benefits of the improved Hot Start on the Fly may include:
** Example for illustration. Actual results may vary depending on plant conditions and other factors.
Scope
Siemens Energy Flex-Power Services™ supplies an integral solution tailored to the specific situation and configuration of the power plant.
Intended Benefits
A start-up from warm conditions may take considerable time for a power plant originally built for less volatile operating profiles.
In competitive markets, the ability to start up your plant faster can help reduce time spent in transient conditions with non-optimal efficiency and make a difference in dispatch.
Warm Start on the Fly has been designed to support
Increased start-up efficiency
*50Hz F-class 1x1 reference case - example only -actual results may vary
Scope
Applicable for many combined cycle power plants with Siemens Energy Design steam turbines and control system
Intended Benefits
A plant shutdown may consume considerable time and fuel for the unloading processes.
In competitive markets, the ability to shutdown your plant faster can help reduce time spent in transient conditions with non-optimal efficiencies and enhance responsiveness.
Fast Plant Shutdown has been designed to support
*50Hz F-class 1x1 reference case - example only -actual results may vary
Scope
Applicable for combined cycle power plants with Siemens Energy Design turbines and control system
Solution
A start-up from a condition where the water-steam cycle has already cooled down significantly may require long holding and waiting times where the gas turbine is running in lower part load for the water-steam cycle to warm up and achieve start release.
The Steam Turbine FlexStart upgrades comprise a range of features focused on the steam turbine designed to shorten the start-up time and enhance start-up flexibibility. Many of the features mainly address enhancements of start-ups from more cooled down conditions, while some of them can also help enhance warm or hot start-ups for combined cycles.
Potential benefits can include:
Scope
Select potential Features
Steam Turbine FlexStart Upgrades can comprise a number of potential features. For a specific unit, the best applicable and matching features are selected based on configuration and detail customer needs. Some of the potential features are:
Advanced Fast Loading
Implementation of Siemens Energy´s advanced speed ramp and load gradient optimization features to the steam turbine controller, adapted to site specific capabilities and conditions. Includes mechanical analysis of steam turbines for enhanced transient capabilities. May also include changes to the unit master control system.
Early Pre-Warming and Modified Pre-Warming Concepts
Designed to help significantly shorten the start-up of H-IL type steam turbines for cold starts through advanced pre-warming concepts for HP (Early Pre-Warming) or IP/LP section (Modified Pre-Warming)
Degassed Conductivity for faster starts of combined cycle power plants
Degassed Conductivity is a method used to analyze steam purity and determine whether the steam can be delivered to the steam turbine. Degassed Conductivity makes it possible to eliminate the contribution of carbon dioxide to the Acid Conductivity (AC).
It has been designed to support
Solution
In combined cycle mode, start-up times are greatly influenced by the configuration and requirements of the water-steam cycle. However, an increase of the gas turbine gradient capabilities may also help with start-up times and start-up efficiency. For the SGT5-4000F, Siemens Energy has developed a start gradient optimization which is designed to
* achievable values may vary by site
Scope
Engineering of solution & applicable logic updates
While on load, upgrades to enhance flexibility can include:
In energy markets with a volatile infeed from various generation sources, combined cycle power plants may find themselves in part load situations for higher shares of their uptime than originally intended.
Enhanced part load capabilities may make a difference in the ability to successfully participate in such generation environment.
Upgrades to enhance part load capabilities can include:
Solution
The Modified ST Valve Staggering upgrade is designed to support lower load operation and to reduce loss of efficiency in this operating condition.
Amongst other criteria, minimum load is typically restricted by logic to avoid high HP exhaust temperatures, and may lead to opening of bypass stations or even shutdown for protection.
The Modified ST Valve Staggering introduces an upgraded logic which has been designed to facilitate modified operations to support lower minimum part load with same or improved margins.
Intended Benefits & Scope
The Modified Valve Staggering upgrade modifies the valve staggering logic for part load operation to help:
Scope
Intended Benefits
Many Gas Turbines have been designed to operate most efficiently at maximum load conditions. With today´s changing market, the need to efficiently operate at part load is becoming more important as well. Siemens Energy has developed a range of solutions to enhance part load capabilities, which can help to:
Advanced preservation concepts and the ability to maintain a plant in a status which allows fast re-start even after multiple days of shutdown may greatly enhance flexibility and support better dispatch success.
Reduced cool-down times may support faster access to components for inspections and repairs, thus supporting shorter outages.
Advanced inspection and interval concepts can help to safeguard and enhance availability.
Intended Benefits
With natural cooling, it may take multiple days for a steam turbine to be sufficiently cooled down to access for inspection or outage work.
Through extensive analysis, Siemens Energy is able to offer Fast Cooling of Steam Turbines which has been designed to significantly accelerate cool-down time and thus help get access to components sooner after shutdown.
Fast Cooling is designed to save up to 3.5 days of cool down time (site specific; actual values may vary) compared to natural cooling,
which may support
Scope
For turbines already equipped with the forced cooling system, Fast Cooling may offer incremental optimization, e. g. improved handling and automation, improved process, etc.
Intended Benefits
Steam Turbine standstills can lead to increased exposure to air moisture which can result in parts corrosion. Preservation measures are recommended to remove and control residual moisture to below recommended thresholds.
Siemens Energy has developed an enhanced preservation system for steam turbines and its auxiliaries to support more flexible shutdowns and longer standstills.
This enhanced dry air system has been designed to help
Scope
Intended Benefits
After a shutdown, the steam turbine and other plant components increasingly cool down the longer the shutdown lasts. Consequently, startup times can correspondingly increase with the duration of the preceding shutdown. Siemens Energy has developed a trace heating system which can keep the relevant steam turbine sections warm or heat them up, and enable a startup from a warmer condition.
Steam Turbine Hot Standby can help
Scope
To help you determine the right solution from the Flex-Power Services™ portfolio ideal for your operational requirements, we conduct a Technical Plant Assessment. It provides detailed insights into the improvement potential for
From Base to Cycling Operation
The paper uses the Mainz Wiesbaden Combined Cycle Power Plant as an example of a plant that has switched from base load to cycling mode as a result of renewable energy input into the grid. The content includes successfully implemented enhancements to improve the plant's operational flexibility. It also includes test results for possible future upgrades.
Contact us to learn more about Flex-Power Services™.