•A low calorific value biogas mixture (50% CH4-50% CO2) is volumetric enriched with hydrogen.•Biogas/Hydrogen mixtures with the lowest flame instability and pollutant emission were determined.•Oxygen ...enrichment was applied to Biogas/Hydrogen mixtures with the lowest instability and emission.•Dynamic pressure fluctuations data in case of external acoustic stress are used in the interpretation of flame instability.•It has been determined that the most stable and low-emission flame is formed by burning the fuel mixture containing 20 % H2 at the rate of 23 % O2 by volume.
The effect of enrichment of a low calorific (50 % CH4-50 % CO2) biogas mixture with hydrogen and oxygen has been investigated on combustion stability and exhaust emissions in a premixed burner. The thermal power was kept constant at 5 kW, the equivalence ratio of 0.8, and a swirl generator (1) was placed at the burner outlet. Initially, hydrogen (H2) was added to the biogas at intervals of 10 % up to 40 % by volume. The addition of hydrogen to the biogas increased the heating value of the mixture and reduced the instabilities. It has been determined that biogas/hydrogen mixtures containing 20 % and 30 % H2 showed the lowest combustion instability and pollutant emissions. It has been observed that with the addition of 30 % hydrogen to the biogas, the CO emission value, which was 5532 ppm, decreased to 130 ppm. Also, 23 % and 25 % O2 enrichment were applied to fuel mixtures. It was observed that combustion instabilities increased with oxygen enrichment in both fuel mixtures and flashbacks occurred under acoustic perturbation. It has been determined that the mixture containing 20 % H2 as the flame, which has the lowest emission and is resistant to acoustic perturbation, is burned at the 23 % O2 ratio by volume.
In this paper, a biogas composition consisting of methane and carbon dioxide mixture in a pilot-scale model burner has been enriched with oxygen and the combustion characteristics including ...combustion stability and emission behaviour have been experimentally investigated. CH4 and CO2 gases have been burned as premixed and the blowout and flashback values of the mixture have been determined. Experiments have been performed at constant equivalence ratio (0.7) and the number of swirl (s = 1) at 3 kW thermal power. To examine the combustion stability, the external acoustic forced condition has been applied with two loudspeakers. Experimental results shown that the highest flame stability has been achieved in the 24% oxygen enrichment rate. The flame extinction occurred at 530 Pa amplitude of 21% oxygen enrichment ratio, although it fluctuated at the dynamic pressure amplitude of 775 Pa at the 24% oxygen enrichment ratio continued to burn. As the enrichment rate was increased to 28%, at the dynamic pressure of 1213 Pa and forced under 175 Hz frequency condition the flashback occurred at the flame. While the oxygen rate increased to 28% it has been observed that a decrease in stability compared to the 24% oxygen rate. Experimental results show that the emissions of CO are 2247 ppm at 21%, 372 ppm at 24% and 10 ppm at 28%. At the same oxygen enrichment rates, the values of NOx are 16 ppm, 1 ppm and 58 ppm, respectively. The decreasing has been observed in NOx emissions up to 24% oxygen enrichment rate.
Synthetic gases attract the attention of researchers due to the increase in energy demand. H2 and CO gases are the main components of synthetic gases. In this study, three different gas mixtures were ...tested according to their H2/CO (3, 1.5, 0.5) ratios. Thermal power (3 kW), swirl number (1) and equivalence ratio (0.7) kept constants for all experiments. Three different oxygen ratios selected for the oxygen enrichment experiments. First, the gas mixture was burned with standard air. After that, the oxygen concentration in the oxidizer was raised to 23 % and 25 % for examining the effect of oxygen enrichment. The stability results showed that an increase of hydrogen content in the synthetic gas mixtures caused decreasing in the oxygen enrichment limit. The mixture, which can be enriched up to 25.8 % O2 while the H2/CO ratios are 0.5, can be increased up to 25.2 % O2 at a medium H2/CO ratio (1.5). In the case where the H2/CO ratio was increased to the high level (3) by increasing the hydrogen level, the oxygen enrichment limit decreased to 24.1 %. A stable flame did not occur after these oxygen enrichment values. In addition, dynamic pressure data were recorded for all mixtures under external acoustic enforcement. Increases in the hydrogen and oxygen ratio at the same time caused the flame instabilities. Thus, the flame extinguished under acoustic enforcement. In addition to these results mentioned, the emission values showed that oxygen enrichment caused the decrease in CO emissions but the increase of NOx values for all synthetic gas mixtures.
•Investigating combustion and emission behaviour of premixed syngas mixtures.•Three different gas mixtures were tested according to their H2/CO (3, 1.5, 0.5) ratios.•Acoustic Frequency conditions in the combustor were changed.•Increasing of the hydrogen content in the mixtures caused decreasing of the oxygen enrichment limit.
The instability changes of oxygen-enriched fuel mixtures under acoustic enforcement in a premixed and swirl supported system were investigated in this study. Different amounts of hydrogen (0%, 10%, ...20%) were added to methane used as fuel and oxygen enrichment process (21%, 24%, 26%) was applied in hydrogen-added fuel mixtures. The equivalence ratio was kept constant at 0.7 in experiments conducted under constant burner power and swirl support. Experiments showed that although oxygen enrichment up to 24% ratio increases stability by increasing the laminar flame speed, stability decreases when the oxygen content in the oxidizer was increased to 26%. As a result of increasing both hydrogen ratio in fuel mixture and oxygen enrichment, instabilities grow up with decreasing of Markstein length. In this situation, burning in combustion chamber did not continue under acoustic force. According to the emission values taken during combustion experiments, the addition of oxygen increased NOx emissions due to increased adiabatic temperature and sudden NOx formations, while contributing to the reduction of CO emissions. Although the addition of hydrogen reduces NOx emissions in case of combustion with air (%21 O2), it has increased the CO emissions from 2 ppm to 13 ppm because it triggers instabilities when combined with oxygen enrichment.
•Investigating combustion and emission behavior of premixed syngas mixtures.•Axial and radial temperature, and emission measurements were performed.•Measuring temperature and pollutant emission ...values throughout the combustor.•Analyzing swirl number and oxygen enrichment on combustion characteristics.
Today, there are many different studies on increasing combustion efficiency and reducing flue gas emission values. In this study, H2 and CO have been added to 30% methane gas in a premixed laboratory scale model burner with high H2 / CO ratio (3) and medium (1.5). Swirl numbers (s = 0.6 and 1) have been changed by keeping the equivalent ratios constant. The experiments have been carried out at a constant burner power (3 kW), regardless of the fuel composition. The effect of the swirl number on the temperature distribution and emission values in the combustion chamber has been investigated radially and axially. At the low swirl number, CO emissions tend to increase with the decrease of H2/CO ratio. On the other hand, at the high swirl number, it has been observed that the decrease in CO emissions with the decrease of H2/CO ratio. Because of the high heating value of the hydrogen, NO emissions increased with the high H2/CO ratio, regardless of the swirl number. As a result of the experiments, it has been concluded that the swirl number and the rate of H2/CO has a great effect on combustion characteristics and emissions of flames. In addition, oxygen enriched combustion has been performed at constant (1) swirl number at different H2/CO ratios. Equivalence ratio was kept constant (0.7) for all experiments. It has been observed that the oxygen-enriched combustion has been caused the low CO and high NO emission at both mixtures. The experiments also showed that the increase of O2 ratio in the air for high H2/CO ratio (3) could be causing the increase in temperature.
In this study, a novel approach has been investigated by using a mixture of thorium and molten salts as a dual-purpose coolant and medium for the production of fissile fuel in a Fusion Fission Hybrid ...Reactor (FFHR) for the reference geometry of ITER. The study highlighted the broader benefits of thorium fuel cycling, safety features, and reduced radioactive minor actinides generation. The use of a thorium-melted salt coolant for fissile fuel production in a fusion-fission hybrid reactor represented a promising path towards efficient and sustainable nuclear energy, with potential benefits in terms of safety features and reduced generation of radioactive minor actinides. In this study, SS 316 LN-IG was selected as the first wall material for the reactor, and a molten salt fuel mixture of LiF–ThF4 was used as the coolant, taking into account the eutectic points of the material, the nominal fusion power in the FFHR for the Tokamak design concept is considered to be 500 MW. The nuclear code MCNP6 was used with the nuclear data libraries ENDF/B-VIII and CLAW-IV for the neutron calculations. The time evolution of the isotopes in the reactor was calculated with the interface code MCNPAS. The study results are evaluated in terms of tritium breeding ratio, energy multiplication factor, radiation damage, fissile fuel production and fuel burn-up value.The 4-year operation history of total TBR value is calculated and always above 1.05 and increases with time.Th initially decreased from 631.3 tonnes to 587.2 tonnes, while 233U production during this period was 9.1 tonnes. According to these results, the first wall replacement period was calculated as 3.9 years.
•Considering the blanket parameters of ITER for Novel approach to Fusion Fission Hybrid Reactor (FFHR).•Successfully demonstrating the potential of using a thorium-molten salt coolant for fissile fuel production.•Employing MCNP6 with ENDF/B-VIII and CLAW-IV nuclear data libraries for neutron calculations.•Demonstrating fissile fuel production, accompanied by 233U production of 9.1 tonnes.•Achieving a TBR above 1.05 and evaluating the fuel burn-up value as a key parameter for reactor performance.
The aim of this study is to investigate tritium breeding ratio (TBR) and first wall material damage parameters such as displacement per atom (DPA), gas production of various coolants with Li2C2 ...tritium breeding material using the three different data libraries (ENDF/B.V, ENDF/B.VI and CLAW IV). Hence, FLiNaK, enriched (90% 6Li) natural lithium, lithium-lead eutectic alloy (Li17Pb83) and FLiBe (Li2BeF4) were used as a coolant (moderator) material for the calculation of the tritium breeding ratio and gas production parameters in a hybrid reactor. Neutronic calculations were performed by Monte Carlo Neutron-Particle Transport code MCNP5 version 1.40 under a neutron wall loud of 2.25 MW/m2 (1014 n/s) by full reactor power for one year. All examined coolant materials were achieved minimum required tritium breeding ratio (TBR > 1.05) and based on radiation damage limits. When the enriched (90%) lithium coolant with lithium carbide breeder used in fusion–fission (hybrid) reactor, vanadium alloy first wall will be replaced every 3.6 and 6.7 years for DPA and Helium production, respectively.
•We investigated tritium breeding ratio and radiation damage in the first wall made of vanadium alloy.•FLiNaK, 90% enriched natural Li, eutectic alloy (Li17Pb83) and FLiBe (Li2BeF4) were performed as a coolant.•90% enriched lithium coolant with lithium carbide tritium breeder shows the best performance.•Vanadium alloy first wall will be replaced every 3.6 and 6.7 years with respect to DPA and He production.
The aim of this paper is to determine neutronic performances of the light water reactor (LWR) spent fuel mixed with fertile thorium fuel in a FFHR. Time dependent three dimensional calculations for ...major technical data, such as blanket energy multiplication, tritium breeding ratio, cumulative fissile fuel enrichment and burnup have been performed by using Monte Carlo Neutron-Particle Transport code MCNP5 1.4, coupled with a novel interface code MCNPAS, which is developed by our research group. A self-sustaining tritium breeding ratio (TBR>1.05) has been kept throughout the calculations. The study has shown that the fissile fuel quality will be improved in the course of the transmutation of the LWR spent in the FFHR. The latter has gained the reusable fuel enrichment level conventional LWRs between one and two years. Furthermore, LWR spent fuel - thorium mixture provides higher burn-up values than in light water reactors. Keywords: LWR spent fuel, Thorium, Time dependent neutronic analysis, Fusion-fission hybrid reactor
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