Jeevan Jayasuriya

Gasified Biomass Fuelled Gas Turbine: Combustion Stability and Selective Catalytic Oxidation of Fuel-Bound Nitrogen

Low heating value of gasified biomass and its fuel bound nitrogen containing compounds challenge the efforts on utilizing gasified biomass on gas turbine combustor. Low heating value of the gas bri ...

Staged Lean Catalytic Combustion of Gasified Biomass for Gas Turbine Applications : an Experimental Approach to Investigate Performance of Catalysts

Environmental and geopolitical concerns encourage societies towards the utilization of renewable energy sources (RES). Photovoltaic and wind power can produce electricity directly, although their intermittent characteristic negatively affects the security and safety of the energy supply chain; moreover, in order to be viable it is necessary to establish energy storage systems and to find mechanisms to adapt the power distribution grid to larger production variability. In contrast, biomass (a carbon neutral fuel if adequately managed) can be stored, is relatively widely available, and after simple treatments can be gasified and ready to be used for power production. Correspondingly, gas turbines are a well-established technology that first became relevant in industrial applications and power production since 1940’s. The use of biomass in gas turbines is an important step forward towards more sustainable power production; however, this combination presents some technical challenges that have yet to be overcome.Gasified biomass is generally a gas with low or medium heating value that is usually composed of a mixture of gases such as CO, H2, CH4, CO2, and N2 as well as other c60*6nents in small fractions. Its firing in standard gas turbine combustors might be unstable at certain load conditions. Moreover, gasified biomass contains undesirable compounds; in particular the nitrogen-containing compounds that may produce elevated NOx emissions once the biomass is burned.Catalytic combustion is an alternative for using gasified biomass in a gas turbine, and it is investigated in this study. Using catalytic combustion is possible to burn such a mixture of gases under very lean conditions, extending the normal flammability limits, reducing the maximum temperature of the reaction zone, and thus reducing the thermal NOx formation. It also reduces the vibration levels, and it is possible to avoid fuel-NOx formation using alternative catalytic techniques, such as Selective Catalytic Oxidation (SCO).In the present study the feasibility of using catalytic combustion in a gas turbine combustor is evaluated. The tests performed indicate the necessity of using hybrid combustion chamber concepts to achieve turbine inlet temperatures levels of modern gas turbines. The different catalytic burning characteristic of H2, CO and CH4 was evaluated and different techniques were applied to equalize their burning behaviour such as the diffusion barrier, and partially coated catalyst. Fuel-NOx is another subject treated in this work, where a Selective Catalytic Oxidation (SCO) technique is applied reaching up to 42% of fuel NOx reduction. Finally, the use of Catalytic Partial Oxidation (CPO) of methane was experimentally investigated.In this study, two one-of-a-kind test facilities were used directly, namely the high-pressure test facility and the pilot scale test facility. This gives a unique characteristic to the study performed. Finally, the catalytic combustion approach allows the utilization of gasified biomass with some restrictions depending on whether it is a Catalytic Lean, Catalytic Rich or Catalytic Partial Oxidation (CPO) approach.

Catalytic Partial Oxidation of Natural Gas in Gas Turbine Applications

Environmental and geopolitical concerns encourage societies towards the utilization of renewable energy sources (RES). Photovoltaic and wind power can produce electricity directly, although their intermittent characteristic negatively affects the security and safety of the energy supply chain; moreover, in order to be viable it is necessary to establish energy storage systems and to find mechanisms to adapt the power distribution grid to larger production variability. In contrast, biomass (a carbon neutral fuel if adequately managed) can be stored, is relatively widely available, and after simple treatments can be gasified and ready to be used for power production. Correspondingly, gas turbines are a well-established technology that first became relevant in industrial applications and power production since 1940’s. The use of biomass in gas turbines is an important step forward towards more sustainable power production; however, this combination presents some technical challenges that have yet to be overcome.Gasified biomass is generally a gas with low or medium heating value that is usually composed of a mixture of gases such as CO, H2, CH4, CO2, and N2 as well as other c60*6nents in small fractions. Its firing in standard gas turbine combustors might be unstable at certain load conditions. Moreover, gasified biomass contains undesirable compounds; in particular the nitrogen-containing compounds that may produce elevated NOx emissions once the biomass is burned.Catalytic combustion is an alternative for using gasified biomass in a gas turbine, and it is investigated in this study. Using catalytic combustion is possible to burn such a mixture of gases under very lean conditions, extending the normal flammability limits, reducing the maximum temperature of the reaction zone, and thus reducing the thermal NOx formation. It also reduces the vibration levels, and it is possible to avoid fuel-NOx formation using alternative catalytic techniques, such as Selective Catalytic Oxidation (SCO).In the present study the feasibility of using catalytic combustion in a gas turbine combustor is evaluated. The tests performed indicate the necessity of using hybrid combustion chamber concepts to achieve turbine inlet temperatures levels of modern gas turbines. The different catalytic burning characteristic of H2, CO and CH4 was evaluated and different techniques were applied to equalize their burning behaviour such as the diffusion barrier, and partially coated catalyst. Fuel-NOx is another subject treated in this work, where a Selective Catalytic Oxidation (SCO) technique is applied reaching up to 42% of fuel NOx reduction. Finally, the use of Catalytic Partial Oxidation (CPO) of methane was experimentally investigated.In this study, two one-of-a-kind test facilities were used directly, namely the high-pressure test facility and the pilot scale test facility. This gives a unique characteristic to the study performed. Finally, the catalytic combustion approach allows the utilization of gasified biomass with some restrictions depending on whether it is a Catalytic Lean, Catalytic Rich or Catalytic Partial Oxidation (CPO) approach.

Experimental Investigations of Catalytic Combustion for High-Pressure Gas Turbine Applications

Catalytic combustion has proven to be a suitable alternative to conventional flame combustion in gas turbines for achieving Ultra-Low Emission levels (ULE). In the process of catalytic combustion, ...

Constructive learning methodology for distant based online education in renewable energy technologies

With the rising concerns about global warming, climate change and the rapid development in the renewable energy industry, many higher educational institutes such as engineering and technological schools around the world have started to offer various educational programs related to sustainable energy pedagogical topics. The knowledge of renewable energy will be a crucial part of scientific literacy for the future; hence it is an absolute necessity to develop easily accessible and flexible-learning approaches in order to succeed in this. Due to various factors, today, the digital online education concept is becoming very popular, both as blended on-campus and as stand-alone studies. Moreover, the traditional teacher-driven education system is being also challenged and new student oriented teaching approaches are currently being identified and practiced by various educational experts. This paper discusses a case study developed by applying the learner-centered teaching concept and implemented as part of an online learning course offered for one month (14 hours of learning time was recommended per week) focusing on renewable energy technology innovations for five student groups in three countries. The methodology section of this paper discuss the application of aligned teaching methodology for designing and constructing the course, content deployment of an existing learning management tool and the implementation and course evaluation. Finally, the assessments were graded and results were analyzed to identify success of the new educational concept applied. A survey questionnaire was also prepared to receive the thoughts about online learning courses and their experience with the online course performed. From an overall point of view, the evaluation and the results exemplify the success and the acceptance of the offered online course by the participants providing good average grading and positive opinions of the method of implementation. Participants also expressed their greater enthusiasm and interest of participating in such online courses for renewable energy engineering, as many of the topics offered through the course are lacking in their existing or past study curriculums.

A simplified method for determining gas turbine performance parameters based upon available catalogue data

Overall theoretical performance analysis of gas turbines can be conducted by applying design parameters into several thermodynamic theories and equations. However, limited availability of the design parameters will not provide sufficient room for a detailed analysis. Gas turbine manufacturers publish only a limited amount of design/performance data, while important parameters remained hidden and the available information is not sufficiently enough for obtaining a complete gas turbine performance dataset. Five main parameters commonly provided by a gas turbine manufacturer’s catalogues; pressure ratio of the compressor, exhaust mass flow rate, exhaust temperature of flue gas, overall efficiency, and electrical output. A theoretical model developed based on Mathcad software as documented in literature is used to reveal other hidden gas turbine parameters. A similar theoretical model using another solver was developed to obtain a complete dataset by using the available catalogue data with additional assumptions, which correspond to the commercial state of the art.The engineering equation solver (EES) software has been used as a platform to rebuild the theoretical model. As the main development, a graphical user interphase (GUI) has been introduced to the new program with the aim to make it more user friendly. Furthermore on top of obtaining the hidden thermodynamic parameters for the gas turbine, performing flue gas analysis and an exergy analysis has now become possible through this program. The developed EES program is expected to be run in the learning laboratory at the Division of Heat and Power Technology, Department of Energy Technology, Royal Institute of Technology (KTH), Stockholm and finally it is going to be incorporated into CompEdu Learning Platform of the same division.Copyright

Evaluation of Reduced Kinetics in Simulation of Gasified Biomass Gas Combustion

It is essentially important to use appropriate chemical kinetic models in the simulation process of gas turbine combustion. To integrate the detailed kinetics into complex combustion simulations has proven to be a computationally expensive task with tens to thousands of elementary reaction steps. It has been suggested that an appropriate simplified kinetics which are computationally efficient could be used instead. Therefore reduced kinetics are often used in CFD simulation of gas turbine combustion. At the same time, simplified kinetics for specific fuels and operation conditions need to be carefully selected to fulfill the accuracy requirements. The applicability of several simplified kinetics for premixed Gasified Biomass Gas (GBG) and air combustion are evaluated in this paper.The current work is motivated by the growing demand of gasified biomass gas (GBG) fueled combustion. Even though simplified kinetic schemes developed for hydrocarbon combustions are published by various researchers, there is little research has been found in literature to evaluate the ability of the simplified chemical kinetics for the GBG combustion. The numerical Simulation tool “CANTERA” is used in the current study for the comparison of both detailed and simplified chemical kinetics. A simulated gas mixture of CO/H2/CH4/CO2/N2 is used for the current evaluation, since the fluctuation of GBG components may have an unpredictable influence on the simulation results. The laminar flame speed has an important influence with flame stability, extinction limits and turbulent flame speed, here it is chosen as an indicator for validation. The simulation results are compared with the experimental data from the previous study [1] which is done by our colleagues. Water vapour which has shown a dilution effect in the experimental study are also put into concern for further validation. As the results indicate, the reduced kinetics which are developed for hydrocarbon or hydrogen combustion need to be highly optimized before using them for GBG combustion. Further optimization of the reduced kinetics is done for GBG and moderate results are achieved using the optimized kinetics compared with the detailed combustion kinetics.Copyright