Benefit from Knowledge and Experience
Here you can find out more about the topics and challenges where we have been able to apply our expertise in the past to develop and implement project-specific solutions for our customers.
With intelligent vibration measurement technology to clean energy
The increasing use of renewable energies from photovoltaic and wind power leads to an increased demand for electrical energy that can be generated quickly if there are fluctuations in solar irradiation or wind supply. Modern gas power plants bridge this supply gap perfectly because they start up quickly and vary their output over a wide range. This complex interaction is significantly supported by intelligent vibration measurement technology. The gas and steam turbine (CCGT) operation has a very good efficiency with low CO2 emissions at the same time - about 60 % less than from brown coal power plants. The currently most modern power plant of this type is located north of Munich in Irsching and has an efficiency of 60.75%. The world's most powerful Siemens machine, the SGT5-8000H gas turbine with an electrical output of over 375 MW, is in operation there.
Test benches for optimizing gas turbines
Siemens has built an ultra-modern test center, the Clean Energy Center (CEC) in Ludwigsfelde, near Berlin. There, individual gas-turbine combustors are operated under high- pressure and pre-heated air or gas conditions – in other words, under realistic conditions. In addition to emissions, thermoacoustic phenomena – also known as combustion dynamics – in the combustion chamber and the dynamic loads on materials are also part of the CEC's investigations. To measure these signals, high-temperature pressure- and, acceleration sensors, strain gauges and various other sensors are used.
The IfTA Solution
In order to learn the most from these various measurements, a specialist vibration measuring tool is part of the advanced technology at the CEC in Ludwigsfelde: the IfTA DynaMaster. DynaMaster is a further development based on the proven IfTA Argus systems that have been in use in various types of gas turbines worldwide, like the SGT5-8000H, for over a decade. Through these approved integrations, five specifications have turned out to be especially decisive.
Flexibility by modularity
All of the CECs test stands are equipped with 32-channel IfTA DynaMasters. All channels are simultaneously sampled for phase-synchronous measurements using 24-bit ADCs and at rates of up to 51.2 kHz. In addition to the fast inputs, 32 slow voltage- or current signals can be measured. There are 16 inputs available for digital signals. The high-speed analog inputs can be tapped via buffered outputs.
This vibration measurement system is rounded off by a powerful modular software platform. IfTA Host, which runs directly on the IfTA DynaMaster, is the hub of measurment-data handling. It allows either manually-controlled or automatic storage of data on the built-in storage medium, which can be either SSD or HD. In addition to vibration data, IfTA Host can also distribute and receive other data via OPC Classic, UA or DataSocket.
The consolidation of all data streams from different sources allows fast and efficient evaluation of complex relationships, such as the effect of environmental parameters or fuel composition on combustion instabilities. Enormous amounts of data result from this application's high sampling rates and sheer number of channels, so the CEC places very specific demands on the abilities of its data analysis. In addition to streams of raw data, collected streams of data are generated over time. This allows a quick overview over long periods of time.
Each sensor is compatible with each input
The heart of this system is the IfTA AD4Pro, a four-channel, dynamic measurement module with universal measurement inputs. This module supports the measurement of voltage- and current signals for each channel. In addition, an integrated differential charge amplifier enables direct connection of piezoelectric high-temperature pressure- and, acceleration sensors. A measuring amplifier for strain gauges is also included, to which quarter-, half- and full bridges can be directly connected. Support for piezoresistive pressure- and acceleration sensors, such as Kulite sensors, and an appropriate power supply for IEPE sensors are also featured. The desired input mode is simply selected via software.
Avoid sources of error and reduce costs
To avoid disturbing ground loops, each of the board's channels is galvanically isolated. This allows shared measurement through sensors in places with high potential differences, as found in large test facilities such as the CEC. The electrical isolation involved is executed in a manner that does not adversely affect signal quality. Thus overall, a signal to noise ratio of up to 145 dB is achieved.
The integration of the amplifier not only reduces costs: the resulting greatly simplified measurement setup also avoids sources of error. Changes in amplifier settings are automatically logged by the system and are thus reproducible at any time. This means that potentially error-prone manual documentation of external amplification factors is no longer necessary. The annual effort involved in calibration is also reduced considerably.
Modern data analysis through user-friendly software
The data analysis software IfTA Trend, which can be used in the system, is a tool with which even files with 10 GB can be quickly loaded and analyzed. In addition to dynamic data and environmental and process parameters, the IfTA DynaMaster also stores calculated values such as peak-to-peak, RMS and entire spectra in the system. These different values are evaluated in specialized plots such as spectrogram, Nyquist plot or Bode plot. In the same software environment, several test engineers monitor the online measurement data streams during the measurement run in individually configurable views. For this purpose, the IfTA Trend on the workstation computer is combined with the IfTA DynaMaster.
Test bench protection facilitated
To ensure protection of the test bench in the event of high vibration amplitudes, the IfTA DynaMaster in the CEC has been upgraded with a real-time capable computing unit (DSP) and output cards to IfTA ArgusOMDS. The modular concept allows a free choice of the desired output card. For example, analog and digital outputs as well as Profibus are available for communication with the test bench control system. The IfTA DynaMaster eliminates many error sources of conventional measuring systems and thus minimizes - not only in the CEC - the risk of incorrect measurements during complex campaigns. Dynamic measurement systems are the indispensable partners on the way to clean energy.
Efficiency increases in gas power plants in the context of energy transition
The cogeneration plant South of SWM shows how it is possible to meet the challenges of the energy revolution under the conditions that no base load is required: Utilization of wind and solar radiation in combination with control power from gas turbines. IfTA's monitoring and early warning system ensures the necessary economic efficiency.
The energy transition and the development towards renewable resources pose new challenges for the energy market. In concrete terms, this means that more and more renewable energy is flowing into the electricity grids with fluctuations due to solar radiation and wind. Control energy is provided to compensate for these fluctuations. Since gas turbines can be flexibly adapted to the electricity demand, they are often used to supply this control energy and thus stabilize the grid. At present, they are not competitive in base-load operation compared with other plants such as coal power plants. In order to supply this control energy, the machines are operated at partial load and thus react quickly to increasing or decreasing energy requirements. A wide usable power range as well as a low partial load limit are important.
Challenges of partial load operation
In a plant test at SWM's South cogeneration plant, the minimum partial load of two GE Frame 9E gas turbines was tested. Using a steam turbine, they form a combined gas and steam plant with additional heat feed into the 800 km long Munich district heating network. The Can-Annular machines each have a rated output of 124 MW, with a lower partial load limit specified by the manufacturer for premixed combustion in compliance with the emission limit values of around 60 MW, depending on atmospheric conditions. The aim is to be able to operate the machines at low loads without any structural modifications. The strategy is to closely monitor the phenomena that limit the minimum load. In addition to emissions, combustion dynamics are a problem in the operating area from time to time. These hardly predictable vibrations, caused by the interaction of acoustics and heat release, can reach very high amplitudes, which impair operation and can even lead to damage.
It has been found that the acoustics spread from can to can through transverse ignition tubes around the entire circumference of the gas turbines. The conditions under which they occur depend not only on the load, but also on atmospheric conditions, transient heating of the machine and contamination of the burner elements.
Knowledge as a basis for effective operation
It has been found that the minimum part load can be reduced to 45 MW, in compliance with applicable emission limits. Since the thermoacoustic circumferential modes are constantly monitored, a change in the stability limit is detected in good time and the gas turbines can always be operated under safe conditions. The reduction of the minimum load by around 20 % allows the flexible use of the machines and corresponds directly to the fuel savings if no electricity is required, but the district heating and/or control power must be covered. In addition, wider power bands can be offered in the auction process on the energy market. All in all, the power plant can thus be operated much more economically.
IfTA research project with University Bundeswehr München and MTU Aero Engines
Interdisciplinary research and development at a high level was successfully carried out as part of a project sponsored by the Free State of Bavaria. After three years of project work, all initially defined goals were achieved: the project partners ISA of university Bundeswehr München, MTU Aero Engines and IfTA GmbH were able to significantly increase the stable operating range of ISA's own Larzac engine with the help of active compressor control using the controller developed by IfTA GmbH. This project was carried out as part of an aviation research program sponsored by the Free State of Bavaria and initiated by university Bundeswehr München.
The project investigated the possibility of actively controlling compressor instabilities on an aircraft gas turbine. The aim of the research was to shift the pump limit of the LARZAC 04 C5 engine compressor available at the Institute for Jet Propulsion with the help of active measures, i.e. the use of a controller, in such a way that the stable operating range is increased and thus the efficiency of the compressor is enhanced.
IfTA as a competent partner
After the first successful control tests of other research institutions on pure test compressors, this work represented a first application on a real and complete aircraft engine. IfTA GmbH supplied the entire controller hardware and software for this project and supported the university in signal acquisition (measurement technology, recording) and interpretation (analysis, algorithms). In addition, further and new developments of the hardware and software were of course carried out during the course of the project in order to enable optimized control.
Thematic of the Central Phenomenon
The range of application of a compressor is limited by the so-called pumping limit, which is expressed in the phenomenon of "pumping" by a flow reversing across the entire cross-section of the compressor. As a weaker and therefore safer "preliminary stage" of this phenomenon, partial flow disturbances, also known as rotating separations, circulating around the circumference of the compressor can also occur. The basic idea behind the active control of a compressor is now to detect the so-called forerunners of a pumping impulse or a rotating separation in good time and to influence the system via a controller and an actuator in such a way that this undesired operation of the compressor does not occur. Modulated air injection at the blade tip area of the first compressor stage has proven to be advantageous, as this is exactly where the instabilities are triggered.
Active control with IfTA systems
Based on a modified form of the AIC system tested in the active instability control of combustion dynamics on stationary gas turbines, various control strategies were developed in the course of the project which were optimized for the respective problem. With the help of these strategies and specially adapted actuators, the research project, which lasted three years, successfully demonstrated the functionality of the active compressor stabilization system. Overall, it was possible to actively shift the pumping limit over the entire speed range of the compressor, thus demonstrating the possibility of industrial application of this innovative technology. Compared to pure constant injection, active stabilization was more efficient, i.e. the same stabilization effect could be achieved with less air or, with the same air consumption, the stable working range was extended beyond the range achievable with constant injection.
The innovative and research-relevant content of this collaboration is reflected in two joint publications at international symposia.
The output of the large combustion burners lies in the upper kW to lower MW range. They are used, for example, in larger offices or department stores, in stadiums or in airports. They no longer have their own combustion chamber, but are operated with various vessels from different manufacturers. This means that the burners must be stable in different geometries under varying conditions. Therefore it is important to know exactly the tendency of the burners to vibrate in order to estimate their instability risk when used in different geometries.
Occurrence of combustion instabilities caused by the burner
In comparison to small furnaces, i.e. condensing boilers, heating appliances, etc., which are intended primarily for domestic use and are offered as complete units, e.g. with burner, combustion chamber, heat exchanger and exhaust system, components from different manufacturers are individually combined in large furnaces. The products manufactured by the burner manufacturer are used, for example, with boilers from another manufacturer. Although combustion instabilities always depend on the overall system, i.e. burner, combustion chamber, exhaust gas and intake system, certain tendencies towards unstable behavior can be identified directly at the burner. For example, combustion phenomena based on fluid mechanical properties generate certain frequency components stronger than others. If these areas are close to an acoustic natural frequency of a boiler and other unfavorable conditions are also met, coupling between combustion and acoustics is probable, i.e. combustion instabilities are stimulated.
IfTA - a competent partner
IfTA GmbH offers various investigations into the causes of combustion dynamics as described above. These investigations include measurements directly on the affected plant or on our customers' test benches. To support the experimental investigations of the phenomena, a numerical simulation of the acoustic behavior of the boiler geometries is also recommended. As a customer, you can rely on a competent, fast and cost-effective handling of your problems, as in the other areas. It goes without saying that we treat every problem confidentially.
In particular, heating appliances used in apartments and residential buildings can seriously impair the quality of life if they exhibit thermoacoustic vibrations. By small firing systems we understand combustion systems in the lower kW range, which are used e.g. as gas heaters, condensing boilers, oil burners etc. in apartments, single-family houses and apartment buildings. Furthermore, these include gas ovens or roasters for canteen kitchens, gas heaters in camping areas and similar systems with a defined combustion chamber geometry in which acoustic natural oscillations can establish themselves, as well as a flame burning in them.
Especially in the field of heaters, in addition to low-emission and efficient operation, quiet combustion is of particular importance, since direct or indirect noise generation by the combustion system can lead to a considerable impairment of the quality of living and thus also of the quality of life. As with large systems, combustion oscillations in small combustion systems can be caused by inconspicuous environmental changes (gas composition, installation conditions, operating point, ambient temperature, etc.). The effects of these changes can be manifold: low-frequency humming with fixed or variable frequency when starting up, sudden, short-term occurrence of instabilities, e.g. caused by closing a door (and the associated pressure surge), high-frequency whistling (about 800Hz, 120dB) when operating at a certain operating point, etc. The effects of these changes can be very different.
Occurrence of combustion instabilities caused by the burner
In comparison to small furnaces, i.e. condensing boilers, heating appliances, etc., which are intended more for domestic use and are offered complete with burner, combustion chamber, heat exchanger and flue gas system, components from different manufacturers are individually combined in large furnaces. The products manufactured by the burner manufacturer are used, for example, with boilers from another manufacturer. Although combustion instabilities always depend on the overall system, i.e. burner, combustion chamber, exhaust gas and intake system, certain tendencies towards unstable behavior can be identified directly at the burner. For example, combustion phenomena based on fluid mechanical properties generate certain frequency components more strongly than others. If these areas are close to an acoustic natural frequency of a boiler and other unfavorable conditions are also met, coupling between combustion and acoustics is probable, i.e. combustion instabilities can be excited.
IfTA as a competent partner
IfTA GmbH offers a wide range of investigations into the causes of combustion instabilities described above. These investigations include measurements directly on the affected plant or on our customers' test benches. To support the experimental investigations of the phenomenon, a numerical simulation of the acoustic behavior of the boiler geometries is also recommended. As a customer, you can rely on a competent, fast and cost-effective handling of your problems, as in the other areas. It is a self-evident fact for us that we treat your problem confidentially.