References on Supporting Decisions
In this group of case studies the Client has had its own detailed concept(s).
Here, the roles of numerical modeling were primarily:
- proving the Client's views correct, incidentally, modifying those in some minor aspects,
- determining the most promising one of the given options.
Consequently, the numerical modeling has provided a well-established theoretical foundation – a reliable recommendation, if you like – on which the Client was able to come to a proper decision.
Here, the roles of numerical modeling were primarily:
- proving the Client's views correct, incidentally, modifying those in some minor aspects,
- determining the most promising one of the given options.
Consequently, the numerical modeling has provided a well-established theoretical foundation – a reliable recommendation, if you like – on which the Client was able to come to a proper decision.
Reduction of the NOx-emission of the Heavy Duty Boiler #5
at the Mátra Power Plant (2010.)
at the Mátra Power Plant (2010.)
Comparison of combustion of different Lignite Fuels in the Heavy Duty Boiler #5
at the Mátra Power Plant (2012.)
at the Mátra Power Plant (2012.)
The observed device is a heavy duty boiler of 650 t/h fresh steam capacity. It was originally designed by MHD, ERŐTERV and EVT Stuttgart.
The objective of this study is gaining better understanding of the boiler's behavior on utilizing different fuels by means of numerical modeling with FLUENT code. The selected fuels are the so called "bükkábrányi lignite" and "visontai lignite". (The naming refers to the neighboring mines, where the lignite fuels have been exploited from.)
The long-term benefit of this observation is to establish the underlying principle for the future operation based on these fuels.
Due to numerical modeling, the processes of the boiler have become known in unparalleled details.
This knowledge is a firm foundation of the operation and the development of this boiler.
The objective of this study is gaining better understanding of the boiler's behavior on utilizing different fuels by means of numerical modeling with FLUENT code. The selected fuels are the so called "bükkábrányi lignite" and "visontai lignite". (The naming refers to the neighboring mines, where the lignite fuels have been exploited from.)
The long-term benefit of this observation is to establish the underlying principle for the future operation based on these fuels.
Due to numerical modeling, the processes of the boiler have become known in unparalleled details.
This knowledge is a firm foundation of the operation and the development of this boiler.
The observed unit is the boiler #5 of Mátra Power Plant. (It has 650 t/h fresh steam capacity. This boiler applies Staged-Air Combustion System to maintain low NOx emission.)
The short-term objective of this project is to build a reliable mathematical model for the given boiler in order to gain better understanding of the production of harmful products like NOx. This model is a virtual reproduction of the real boiler, which provides qualitative and quantitative information about the real processes.
Usage of concrete boundary conditions and experimental data for validation has led to the "reference model" of the boiler, which is a ground for comparison of further modeled cases.
The long-term objective of this project is to support the planning of the economical mode of operation for the boiler. Accordingly, three modified cases have been modeled, then examined, in order to demonstrate the positive effect of biomass co-firing on the boiler:
• 20% Biomix 80% Lignite co-firing,
• 30% Biomix 70% Lignite co-firing,
• 3% Depogas 97% Lignite co-firing.
Where "Biomix" is a mixture of wood-based solid bio fuels, while "Depogas" is an organic gaseous fuel.
The short-term objective of this project is to build a reliable mathematical model for the given boiler in order to gain better understanding of the production of harmful products like NOx. This model is a virtual reproduction of the real boiler, which provides qualitative and quantitative information about the real processes.
Usage of concrete boundary conditions and experimental data for validation has led to the "reference model" of the boiler, which is a ground for comparison of further modeled cases.
The long-term objective of this project is to support the planning of the economical mode of operation for the boiler. Accordingly, three modified cases have been modeled, then examined, in order to demonstrate the positive effect of biomass co-firing on the boiler:
• 20% Biomix 80% Lignite co-firing,
• 30% Biomix 70% Lignite co-firing,
• 3% Depogas 97% Lignite co-firing.
Where "Biomix" is a mixture of wood-based solid bio fuels, while "Depogas" is an organic gaseous fuel.
The Client's main question is:
What overall numeric values characterize the given boiler under the condition of utilizing either pure "bükkábrányi lignite" or pure "visontai lignite"?
What overall numeric values characterize the given boiler under the condition of utilizing either pure "bükkábrányi lignite" or pure "visontai lignite"?
The Client's main question is:
What sort of mixture of possible fuels provides the lowest level of emission of NOx in the given boiler?
What sort of mixture of possible fuels provides the lowest level of emission of NOx in the given boiler?
Client: Mátra Power Plant Share Company, (Hungary)
The results of the numerical modelings – calculated by means of FLUENT software – have been nested into the directives of boiler operation.
See the brief summary in the animation below:
See the brief summary in the animation below:
Modeling of Tail-Gas Incinerator
– Elimination of Overheating the walls (2007,)
– Flame Stabilization at minimum load (2008.)
– Elimination of Overheating the walls (2007,)
– Flame Stabilization at minimum load (2008.)
Within the soot-making process a special equipment is used for destruction of the byproduct, the so-called tail-gas. This equipment provides sufficiently high temperature and residence time for the optimal burnout for this gas mixture.
Operation experiences have shown that certain wall elements have been exposed to abnormally high heat transfer, which may cause tripping of the equipment and jeopardizes the continuous production.
Numerical modeling by means of FLUENT software helped to reveal the source of overheating and to develop an economical procedure to solve it.
Previous studies have supported the homogeneous parameter distributions at nominal load using partially pre-mixed combustion and suitable modification of the fuel injections. However, experiences have uncovered certain flame instabilities close to minimum load.
Operation experiences have shown that certain wall elements have been exposed to abnormally high heat transfer, which may cause tripping of the equipment and jeopardizes the continuous production.
Numerical modeling by means of FLUENT software helped to reveal the source of overheating and to develop an economical procedure to solve it.
Previous studies have supported the homogeneous parameter distributions at nominal load using partially pre-mixed combustion and suitable modification of the fuel injections. However, experiences have uncovered certain flame instabilities close to minimum load.
The Client's main questions are:
- What is the source of the overheating effect and how can it be eliminated?
- What sort of modifications are needed in order to perform stable operation at low loads?
- What is the source of the overheating effect and how can it be eliminated?
- What sort of modifications are needed in order to perform stable operation at low loads?
Client: VEIKI Share Company (Hungary)
In order to get rid of this problem, application of a turbulent diffusion flame structure has been suggested at low loads. The prospective parameter distributions have been predicted by means of numerical modeling as a supporting tool for the design of the modifications of the equipment.
Checking of Parameter Distributions of a Duct Burner for a Gas Turbine + HRSG unit (2008)
The client would like to use its duct burner to increase the flue gas temperature of a given Gas Turbine, in order to intensify the heat transfer within the joining Heat Recovery Steam Generator (HRSG).
Since this specially designed, natural gas fired duct burner has not been used under exactly this kind of circumstances, the observation focuses on the examination of the burner's suitability, and - if it is necessary – determination of the required modifications.
Two different levels of reduction have been applied to simulate the complex chemical reactions. We used:
– an overly simplified reaction mechanism (3 reactions among 7 species),
Since this specially designed, natural gas fired duct burner has not been used under exactly this kind of circumstances, the observation focuses on the examination of the burner's suitability, and - if it is necessary – determination of the required modifications.
Two different levels of reduction have been applied to simulate the complex chemical reactions. We used:
– an overly simplified reaction mechanism (3 reactions among 7 species),
The Client's main questions are:
- Is the given duct burner suitable for the cooperation with the specified gas turbine or not?
- Can the complete burnout of the natural gas be reached within the available space of the existing duct?
- Is the given duct burner suitable for the cooperation with the specified gas turbine or not?
- Can the complete burnout of the natural gas be reached within the available space of the existing duct?
Client: GB-Ganz Limited (Hungary)
According to the simulation results, it has been found that the original design provides sufficient circumstances for the complete burnout. On the other hand, the actual boundary conditions are appropriate for the given duct burner. Consequently, the duct burner will operate properly in all likelihood. Needless to modify the duct burner for the observed set of boundary conditions.
Later, experimental results have justified the predictions of the numerical calculations. The appropriateness of the design of the duct burner is proved to be true.
Later, experimental results have justified the predictions of the numerical calculations. The appropriateness of the design of the duct burner is proved to be true.
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Supporting the Change of Fuel,
Development of New Combustion System for alternative Fuels (2013,)*
Development of New Combustion System for alternative Fuels (2013,)*
The Client's obvious questions were:
- Are the existing boilers capable of utilizing SRF and rubber?
- If so, what kind of negative side effects would appear?
- And what do we have to modify on the boilers in order to compensate/minimize these unwanted effects?
- Are the existing boilers capable of utilizing SRF and rubber?
- If so, what kind of negative side effects would appear?
- And what do we have to modify on the boilers in order to compensate/minimize these unwanted effects?
Client: VÉRT Share Company (Hungary)
The observed devices are two heavy duty boilers of 230 t/h fresh steam capacity each.
In this case, two heavy-duty boilers was originally designed for lignite combustion; later for lignite and wood-chips co-firing by means of a special hybrid-fluid combustion system. Having depleted the prime fuel of lignite the client was looking for the usage of alternative fuels. In the future Solid Recovered Fuel (SRF) and rubber waste appeared to be a potential candidate for this purpose. However, these new fuels have considerably different material properties than the design fuels have. For example, the heating value is three times higher, while the moisture content is one tenth than that of the lignite.
Intensive numerical study began. Based on the detailed empirical analyses of the fuel samples (including T, TG, DTG, DTA and DDTA thermogravimetric observations, among standard immediate and ultimate analyses) a highly reliable 3-dimensional combustion model have been built. The processes of the fluidized-bed have been calculated with a special emprical submodel, developed by Gy. Plaveczky (VEIKI).
Many cases have been performed with various combustion configurations. Fortunately, the numerical results proved that these bolers are able to operate using SRF and rubber waste, furthermore, after applying minor modifications (on the angle of the burners, and the air distribution, in addition applying flue-gas recirculation), a fine-tuned new configuration is able to provide acceptable thermal efficiency and NOx/CO emission as well.
The models of the original pulverized coal firing system (RUN-17) and the special hybrid-fluid combustion system (RUN-22) served as reference cases for the fine-tuning investigation. The results of the best combustion configuration found by means of this study (labeled as RUN-64, being the 64th case of the investigation) can be seen in the middle of the animation, so it can easily be compared to the reference cases on the two sides.
This study have paved the way towards the last phase of development, in which the optimal method of transient processes, like ignition and load-change, can be specified particularly. (Unfortunately, that phase, due to external reasons, have not attained.)
In this case, two heavy-duty boilers was originally designed for lignite combustion; later for lignite and wood-chips co-firing by means of a special hybrid-fluid combustion system. Having depleted the prime fuel of lignite the client was looking for the usage of alternative fuels. In the future Solid Recovered Fuel (SRF) and rubber waste appeared to be a potential candidate for this purpose. However, these new fuels have considerably different material properties than the design fuels have. For example, the heating value is three times higher, while the moisture content is one tenth than that of the lignite.
Intensive numerical study began. Based on the detailed empirical analyses of the fuel samples (including T, TG, DTG, DTA and DDTA thermogravimetric observations, among standard immediate and ultimate analyses) a highly reliable 3-dimensional combustion model have been built. The processes of the fluidized-bed have been calculated with a special emprical submodel, developed by Gy. Plaveczky (VEIKI).
Many cases have been performed with various combustion configurations. Fortunately, the numerical results proved that these bolers are able to operate using SRF and rubber waste, furthermore, after applying minor modifications (on the angle of the burners, and the air distribution, in addition applying flue-gas recirculation), a fine-tuned new configuration is able to provide acceptable thermal efficiency and NOx/CO emission as well.
The models of the original pulverized coal firing system (RUN-17) and the special hybrid-fluid combustion system (RUN-22) served as reference cases for the fine-tuning investigation. The results of the best combustion configuration found by means of this study (labeled as RUN-64, being the 64th case of the investigation) can be seen in the middle of the animation, so it can easily be compared to the reference cases on the two sides.
This study have paved the way towards the last phase of development, in which the optimal method of transient processes, like ignition and load-change, can be specified particularly. (Unfortunately, that phase, due to external reasons, have not attained.)
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Due to practical reasons L. L. Varga has performed this references on behalf of MVM ERBE Share Company (Hungary)
