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Figure 3.3: Test ng and instruments The Figure 3.3 below shows the test rig devices, used for this work.

Figure 3 3: Test ng and instruments The Figure 3.3 below shows the test rig devices, used for this work.

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Figure 1.1: Global mean land-ocean temperature changes from 1880-2012. The black line is the annual mean and the red line is the 5-year running mean. The green bars show uncertainty estimates’. Scientists are 95-100% certain that the temperature increase is primarily caused by increasing concentrations of greenhouse gases produced by anthropogenic activities such as the burning of fossil fuels and deforestation’. A relative Contribution of greenhouse gas emissions to global warming was published in 1990° which showed the greenhouse gases sources.
Figure 1.1: Global mean land-ocean temperature changes from 1880-2012. The black line is the annual mean and the red line is the 5-year running mean. The green bars show uncertainty estimates’. Scientists are 95-100% certain that the temperature increase is primarily caused by increasing concentrations of greenhouse gases produced by anthropogenic activities such as the burning of fossil fuels and deforestation’. A relative Contribution of greenhouse gas emissions to global warming was published in 1990° which showed the greenhouse gases sources.
Figure 1.2: Annual world greenhouse gas emissions, in 2005” The major greenhouse gases are water vapor, which causes about 36-70% of the greenhouse effect; carbon dioxide (CO2), which causes 9-26%; methane (CH,), which causes 4-9%; and ozone (O3), which causes 3-7%°. Observation relating CO, concentration with average Earth’s temperature included® ’. Figure 1.2 shows the annual world greenhouse gases emissions in 2005 by sector.
Figure 1.2: Annual world greenhouse gas emissions, in 2005” The major greenhouse gases are water vapor, which causes about 36-70% of the greenhouse effect; carbon dioxide (CO2), which causes 9-26%; methane (CH,), which causes 4-9%; and ozone (O3), which causes 3-7%°. Observation relating CO, concentration with average Earth’s temperature included® ’. Figure 1.2 shows the annual world greenhouse gases emissions in 2005 by sector.
A scenario for a Warm, High-CO2 World was published as early as 19808 clarifying that human activities are altering the carbon cycle both by adding more CO 2 to the atmosphere as well as by influencing the ability of natural sinks, like forests, to remove CO, from the atmosphere. While CO2 emissions come from a variety of natural sources, human-related emissions are responsible for the increase that has occurred in the atmosphere since the industrial revolution.
A scenario for a Warm, High-CO2 World was published as early as 19808 clarifying that human activities are altering the carbon cycle both by adding more CO 2 to the atmosphere as well as by influencing the ability of natural sinks, like forests, to remove CO, from the atmosphere. While CO2 emissions come from a variety of natural sources, human-related emissions are responsible for the increase that has occurred in the atmosphere since the industrial revolution.
Figure 1.5: Projections of global mean sea level rise’”
Figure 1.5: Projections of global mean sea level rise’”
Figure 1.6: The three CO» capture processes
Figure 1.6: The three CO» capture processes
Flames stabilized the perforated-plates used at the operating testing can be considered as a multi Bunsen flame. The flames showed a seated blue inner premixed flame and outer diffusion flame. The maximum flame temperature is obtained at the tip of the inner premixed cones. The shape and size of the inner cones depend on the burning velocity and its balance with the normal component of combustible mixture flow as it is shown in Figure 1. 7 The combustion in the perforated bu gives a multi Bunsen type flame. It was characterized by two reaction zones: The first reaction zone is observed as a conditions, where the rate of b set of multi uring dep the flame front depends on the ratio of this zone, a secondary, diffusi controlled by the mixing rate b on-contro cones, and its mixing rate with the outsi reaction zones and results in di ends led U-Ccon mer under partially-premixed flame conditions ical primary flames, governed by the premixed solely on the burning velocity, and the shape of the burning velocity to the mixture velocity. Above flame is developed, where the flame length is etween the unbumed fuel and oxygen from the premixed inner de entrained air. The burner geometry affects both ‘ferent combusti on characteristics.
Flames stabilized the perforated-plates used at the operating testing can be considered as a multi Bunsen flame. The flames showed a seated blue inner premixed flame and outer diffusion flame. The maximum flame temperature is obtained at the tip of the inner premixed cones. The shape and size of the inner cones depend on the burning velocity and its balance with the normal component of combustible mixture flow as it is shown in Figure 1. 7 The combustion in the perforated bu gives a multi Bunsen type flame. It was characterized by two reaction zones: The first reaction zone is observed as a conditions, where the rate of b set of multi uring dep the flame front depends on the ratio of this zone, a secondary, diffusi controlled by the mixing rate b on-contro cones, and its mixing rate with the outsi reaction zones and results in di ends led U-Ccon mer under partially-premixed flame conditions ical primary flames, governed by the premixed solely on the burning velocity, and the shape of the burning velocity to the mixture velocity. Above flame is developed, where the flame length is etween the unbumed fuel and oxygen from the premixed inner de entrained air. The burner geometry affects both ‘ferent combusti on characteristics.
Figure 2. 1: Represents an instability pattern diagram for CH4/CO2/O>2 flame (@ =0.9)
Figure 2. 1: Represents an instability pattern diagram for CH4/CO2/O>2 flame (@ =0.9)
Figure 2. 2: Laminar flame velocity versus adiabatic flame temperature Shroll et al. 2011 indicated that the laminar burning velocity has been shown to be significantly lower for oxy-fuel combustion because of the adverse effects of adding CO2 in the oxidizer mixture. Figure 2.3 showed the laminar flame velocity as a function of adiabatic flame temperature. The laminar burning velocity appeared linear for air-fuel combustion, while increased more quickly at higher temperatures for oxy-fuel combustion.
Figure 2. 2: Laminar flame velocity versus adiabatic flame temperature Shroll et al. 2011 indicated that the laminar burning velocity has been shown to be significantly lower for oxy-fuel combustion because of the adverse effects of adding CO2 in the oxidizer mixture. Figure 2.3 showed the laminar flame velocity as a function of adiabatic flame temperature. The laminar burning velocity appeared linear for air-fuel combustion, while increased more quickly at higher temperatures for oxy-fuel combustion.
Figure 2. 4: Stable flame operation for different mixtures and power levels The figure below shows the range of stable flame operation for different oxidizer compositions and thermal powers versus Reynolds number. The Reynolds number is calculated using the minimum effective flow cross-section of the burner outer co-swirl nozzle 25 mm with flow calculated for standard temperature and pressure. The plot indicated that as the O2 content in the oxidizer is increased the flame can be operated stably for much leaner conditions. This can be attributed to two effects: The flame speed and/or the Reynolds number. It could be concluded that, the higher flame speed assists flame stabilization and lean operation at higher Oz levels. Also O» fraction had a strong influence on the flame shape, where changes in equivalence ratio only had marginal effects.
Figure 2. 4: Stable flame operation for different mixtures and power levels The figure below shows the range of stable flame operation for different oxidizer compositions and thermal powers versus Reynolds number. The Reynolds number is calculated using the minimum effective flow cross-section of the burner outer co-swirl nozzle 25 mm with flow calculated for standard temperature and pressure. The plot indicated that as the O2 content in the oxidizer is increased the flame can be operated stably for much leaner conditions. This can be attributed to two effects: The flame speed and/or the Reynolds number. It could be concluded that, the higher flame speed assists flame stabilization and lean operation at higher Oz levels. Also O» fraction had a strong influence on the flame shape, where changes in equivalence ratio only had marginal effects.
The flow di bumer and tl diagram of the air- degree of pre in Figure 3.3. The controllers, measuri system and p agram he oxidizer fuel combustion experiments with van mixing (L/D of oxy-fuel combustion experimen mixture made of CO2/O2 flow diag ts shows the fuel inlet to the rams in Figure 3.1. The flow iable fuel inlet used to control the is shown in Figure 3.2and a digital picture for the test rig is shown test rig consists of an oxidizer supply sys tem, fuel supply system, flow ng ins trumentation, pilot flame burner, mai urging system. n burner, confinement, exhaust
The flow di bumer and tl diagram of the air- degree of pre in Figure 3.3. The controllers, measuri system and p agram he oxidizer fuel combustion experiments with van mixing (L/D of oxy-fuel combustion experimen mixture made of CO2/O2 flow diag ts shows the fuel inlet to the rams in Figure 3.1. The flow iable fuel inlet used to control the is shown in Figure 3.2and a digital picture for the test rig is shown test rig consists of an oxidizer supply sys tem, fuel supply system, flow ng ins trumentation, pilot flame burner, mai urging system. n burner, confinement, exhaust
Figure 3.2: Flow diagram for air experiment oxidizer mixture contains oxygen and carbon dioxides gases. The pressure and temperature of each gas is measured via rotameter and then a thermocouple respectively. These gases are mixed in a mixer at degree of premixing of 128. The oxidizer and the fuel are introduced together into the burner at degree of premixing of 7.
Figure 3.2: Flow diagram for air experiment oxidizer mixture contains oxygen and carbon dioxides gases. The pressure and temperature of each gas is measured via rotameter and then a thermocouple respectively. These gases are mixed in a mixer at degree of premixing of 128. The oxidizer and the fuel are introduced together into the burner at degree of premixing of 7.
A perforated plate burner (3 mm thick, 30-mm outer diameter, with 22 holes 4-mm each and made of steel, shown in Figure 3.4) is used in this work since multi recirculation zones occur downstream of every hole improving the flame stability. The stability of multi- hole plate burner at ultra-lean mixing conditions was found to be higher than that of an ordinary large size single-hole bumer.
A perforated plate burner (3 mm thick, 30-mm outer diameter, with 22 holes 4-mm each and made of steel, shown in Figure 3.4) is used in this work since multi recirculation zones occur downstream of every hole improving the flame stability. The stability of multi- hole plate burner at ultra-lean mixing conditions was found to be higher than that of an ordinary large size single-hole bumer.
Figure 3.5: Digital image of perforated-plate burner 3.3. Operation procedure
Figure 3.5: Digital image of perforated-plate burner 3.3. Operation procedure
Table 3.1: Specifications of Air and C O2 rotameters
Table 3.1: Specifications of Air and C O2 rotameters
Table 3.4: Oxidizer mixture properties for oxygen fraction of 36% for oxy-fuel combustion Table 3.5: Oxidizer mixture properties for oxygen fraction of 32% for oxy-fuel combustion
Table 3.4: Oxidizer mixture properties for oxygen fraction of 36% for oxy-fuel combustion Table 3.5: Oxidizer mixture properties for oxygen fraction of 32% for oxy-fuel combustion
Figure 4. 1: Flammability limits, oxy-fuel combustion, O.F. 36%, L/D =7 In this subsection, the run set number is O1. The results of flammability limits at yxygen fraction of 36% are presented and discussed.
Figure 4. 1: Flammability limits, oxy-fuel combustion, O.F. 36%, L/D =7 In this subsection, the run set number is O1. The results of flammability limits at yxygen fraction of 36% are presented and discussed.
Figure 4, 2: Visual flame appearance (Outer cones), oxy—fuel combustion, O.F. = 36%, L/D =7, the bummer diameter is shown as a length scale it measures 3 cm.
Figure 4, 2: Visual flame appearance (Outer cones), oxy—fuel combustion, O.F. = 36%, L/D =7, the bummer diameter is shown as a length scale it measures 3 cm.
Figure 4. 4: Flammability limits, oxy—fuel combustion, O.F. 32%, L/D =7 In this subsection, the run set number is O2. The results of flammability limits at xygen fraction of 32% are presented and discussed.
Figure 4. 4: Flammability limits, oxy—fuel combustion, O.F. 32%, L/D =7 In this subsection, the run set number is O2. The results of flammability limits at xygen fraction of 32% are presented and discussed.
Figure 4. 5: Visual flame appearance (Outer cones), oxy—fuel combustion, O.F. = 32%, L/D = 7, the burner diameter is shown as a length scale it measures 3 cm.
Figure 4. 5: Visual flame appearance (Outer cones), oxy—fuel combustion, O.F. = 32%, L/D = 7, the burner diameter is shown as a length scale it measures 3 cm.
Figure 4. 7: Flammability limits, oxy-fuel combustion, O.F. 29%, L/D =7 In this subsection, the run set number is O3. The results of flammability limits at oxygen fraction of 29% are presented and discussed. Figure 4. 7 shows the lower and upper flammability limits for the oxy-fuel combustion case at L/D =7 and an oxygen fraction of 29%. It can be seen from the figure that the flammability limits decrease as compared with figure 4.1 and 4.4 of oxygen fractions 36 % and 32 % respectively, and the flammability limits increase as the oxidizer mass flow rate increases, due to the increased turbulence. Figure 4.12 compares these results with those obtained at different oxygen fraction as well as those obtained in air.
Figure 4. 7: Flammability limits, oxy-fuel combustion, O.F. 29%, L/D =7 In this subsection, the run set number is O3. The results of flammability limits at oxygen fraction of 29% are presented and discussed. Figure 4. 7 shows the lower and upper flammability limits for the oxy-fuel combustion case at L/D =7 and an oxygen fraction of 29%. It can be seen from the figure that the flammability limits decrease as compared with figure 4.1 and 4.4 of oxygen fractions 36 % and 32 % respectively, and the flammability limits increase as the oxidizer mass flow rate increases, due to the increased turbulence. Figure 4.12 compares these results with those obtained at different oxygen fraction as well as those obtained in air.
Figure 4. 8: Visual flame appearance(Outer cones), oxy—fuel combustion, O.F. = 29%, L/D = 7, the burner diameter is shown as a length scale and its measures 3 cm.
Figure 4. 8: Visual flame appearance(Outer cones), oxy—fuel combustion, O.F. = 29%, L/D = 7, the burner diameter is shown as a length scale and its measures 3 cm.
Figure 4. 9: Inner cones shape, oxy—fuel combustion, O.F. =29%, L/D =7, the burner diameter is shown as a length scale and its measures 3 cm.
Figure 4. 9: Inner cones shape, oxy—fuel combustion, O.F. =29%, L/D =7, the burner diameter is shown as a length scale and its measures 3 cm.
Figure 4. 10: Extinction mechanism, oxy-fuel combustion, going to less fuel, O.F. = 29% , oxidizer mass flow rate 1.32 kg/hr, L/D =7
Figure 4. 10: Extinction mechanism, oxy-fuel combustion, going to less fuel, O.F. = 29% , oxidizer mass flow rate 1.32 kg/hr, L/D =7
Figure 4. 11: Extinction mechanisms, oxy-fuel combustion, going to more fuel, O.F. = 32%. oxidizer mass flow rate of 1.32 kg/hr, L/D =7 The extinction mechanism at the upper flammability limit is inferred by obtaining a stable flame and then increasing the fuel flow rate until extinction mechanism occurs. Figure 4. 11 shows the sequence of digital flame images of stable flames until extinction occurs as the equivalence ratio increases from 1.0 to 1.1 until blow-off occurs. Note that the unsymmetrical flame shape is due to the existence of a hot spot caused by the igniter.
Figure 4. 11: Extinction mechanisms, oxy-fuel combustion, going to more fuel, O.F. = 32%. oxidizer mass flow rate of 1.32 kg/hr, L/D =7 The extinction mechanism at the upper flammability limit is inferred by obtaining a stable flame and then increasing the fuel flow rate until extinction mechanism occurs. Figure 4. 11 shows the sequence of digital flame images of stable flames until extinction occurs as the equivalence ratio increases from 1.0 to 1.1 until blow-off occurs. Note that the unsymmetrical flame shape is due to the existence of a hot spot caused by the igniter.
Figure 4.13 below summarizes and compares the results of figures 4.2, 4.5, and 4.8. As shown in Figure 4. 13, the flame length increases while decreasing the oxygen fraction from 36% to 29% this is due to lower chemical reaction rate associated with lower oxygen in the oxidizer mixture. The flame length is also observed to decrease while decreasing the equivalence ratio, this observation considered with Takeshi Y okomoni et al.
Figure 4.13 below summarizes and compares the results of figures 4.2, 4.5, and 4.8. As shown in Figure 4. 13, the flame length increases while decreasing the oxygen fraction from 36% to 29% this is due to lower chemical reaction rate associated with lower oxygen in the oxidizer mixture. The flame length is also observed to decrease while decreasing the equivalence ratio, this observation considered with Takeshi Y okomoni et al.
This section presents the flammability limits of the 2" set of experiments. The run set number is O04. The flammability limits are shown in figure 4.14. Flash back occurs when increasing the oxygen fraction over 40% and blow-off extinction mechanism occurs when decreasing the oxygen fraction below 28 %.
This section presents the flammability limits of the 2" set of experiments. The run set number is O04. The flammability limits are shown in figure 4.14. Flash back occurs when increasing the oxygen fraction over 40% and blow-off extinction mechanism occurs when decreasing the oxygen fraction below 28 %.
Figure 4. 17: Flammability limits, air-fuel combustion, L/D =7 Figure 4. 17shows the lower and upper flammability limits for the air-fuel combustion case at L/D of 7.It can be seen from the figure that the flammability limits increase as the oxidizer mass flow rate increases, due to the increase in turbulence. Figure 4. 30 compares these results with those obtained at different degree of premixing L/D in the range of 7 to 128. Air-fuel combustion, L/D =7
Figure 4. 17: Flammability limits, air-fuel combustion, L/D =7 Figure 4. 17shows the lower and upper flammability limits for the air-fuel combustion case at L/D of 7.It can be seen from the figure that the flammability limits increase as the oxidizer mass flow rate increases, due to the increase in turbulence. Figure 4. 30 compares these results with those obtained at different degree of premixing L/D in the range of 7 to 128. Air-fuel combustion, L/D =7
Figure 4. 18: Visual flame length and appearance, air-fuel combustion, L/D=7, the bummer diameter is shown as a length scale and its measures 3cm.
Figure 4. 18: Visual flame length and appearance, air-fuel combustion, L/D=7, the bummer diameter is shown as a length scale and its measures 3cm.
Figure 4. 19: Inner cones shape, air-fuel combustion, L/D = 7
Figure 4. 19: Inner cones shape, air-fuel combustion, L/D = 7
Figure 4. 20: Extinction mechanism, air-fuel combustion, L/D = 7
Figure 4. 20: Extinction mechanism, air-fuel combustion, L/D = 7
Figure 4. 21: Flammability limits, air-fuel combustion, L/D = 25
Figure 4. 21: Flammability limits, air-fuel combustion, L/D = 25
This section presents the upper and lower flammability limits and visual flame appearance while burning in air at premixing ratio of 45. Figure 4. 23: Flammability limits, air-fuel combustion, L/D = 45
This section presents the upper and lower flammability limits and visual flame appearance while burning in air at premixing ratio of 45. Figure 4. 23: Flammability limits, air-fuel combustion, L/D = 45
Figure 4. 25: Flammability limits, air-fuel combustion, L/D = 67 This section presents the upper and lower flammability limits and visual flame appearance while burning in air at premixing ratio of 67. Figure 4. 25, shows the lower and upper flammability limits for the air-fuel combustion case at premixing ratio of 67, It can be seen from the figure that the flammability limits decreases as compared with Figure 4. 17,Figure 4. 21and Figure 4. 23 for premixing ratios of 7, 25, and 45 respectively, also the flammability limits increase as the oxidizer mass flow rate increases, due to the increase in turbulence. Figure 4. 30, compares these results with those obtained at different premixing ratios, L/D in the range of 7 to 128.
Figure 4. 25: Flammability limits, air-fuel combustion, L/D = 67 This section presents the upper and lower flammability limits and visual flame appearance while burning in air at premixing ratio of 67. Figure 4. 25, shows the lower and upper flammability limits for the air-fuel combustion case at premixing ratio of 67, It can be seen from the figure that the flammability limits decreases as compared with Figure 4. 17,Figure 4. 21and Figure 4. 23 for premixing ratios of 7, 25, and 45 respectively, also the flammability limits increase as the oxidizer mass flow rate increases, due to the increase in turbulence. Figure 4. 30, compares these results with those obtained at different premixing ratios, L/D in the range of 7 to 128.
Figure 4. 27: Flammability limits, air-fuel combustion, L/D = 128
Figure 4. 27: Flammability limits, air-fuel combustion, L/D = 128
Figure 4. 30: Summary of the effects of the premixing ratio (L/D) on flammability limits ir air In the Figure 4. 30below, the comparison is made for the flammability limits all premixing ratios namely 7, 25, 45, 67 and 128 at the same air mass flow rates in the range of 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6 and 1.7 kg/hr. it’s observed that the higher range of flammability limits occurs at the lower premixing ratio of 7, and the lower flammability limits occurs at the higher premixing ratio of 128.
Figure 4. 30: Summary of the effects of the premixing ratio (L/D) on flammability limits ir air In the Figure 4. 30below, the comparison is made for the flammability limits all premixing ratios namely 7, 25, 45, 67 and 128 at the same air mass flow rates in the range of 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6 and 1.7 kg/hr. it’s observed that the higher range of flammability limits occurs at the lower premixing ratio of 7, and the lower flammability limits occurs at the higher premixing ratio of 128.
Figure 4, 31: Air-fuel combustion, flame appearance at different degree of premixing
Figure 4, 31: Air-fuel combustion, flame appearance at different degree of premixing
Figure 4, 32: Air-fuel combustion, summary of variation of flame length In the Figure 4. 32 below, the comparison is made on the flame length of all premixing ratios namely 7, 25, 45, 67 and 128 at the same equivalence ratios, and it is observed that the flame length increases while decreasing the premixing this can be attributed to enhancing premixing.
Figure 4, 32: Air-fuel combustion, summary of variation of flame length In the Figure 4. 32 below, the comparison is made on the flame length of all premixing ratios namely 7, 25, 45, 67 and 128 at the same equivalence ratios, and it is observed that the flame length increases while decreasing the premixing this can be attributed to enhancing premixing.
Table 5.2: Summary of results of the second set of experiments of oxy-fuel combustion
Table 5.2: Summary of results of the second set of experiments of oxy-fuel combustion
Table 5.3: Summary of results of the third set of experiments (air-fuel combustion)
Table 5.3: Summary of results of the third set of experiments (air-fuel combustion)
A specific flow meter which was calibrated for air, normal density 1.293 kg/m? is to be used for nitrogen, normal density 1.25 kg/m*. Read the factor 1.02 (heavy border) from the intersection of Air column and the Nitrogen row. The flow rate values indicated by the flow meter are to be multiplied by this factor.
A specific flow meter which was calibrated for air, normal density 1.293 kg/m? is to be used for nitrogen, normal density 1.25 kg/m*. Read the factor 1.02 (heavy border) from the intersection of Air column and the Nitrogen row. The flow rate values indicated by the flow meter are to be multiplied by this factor.
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Oxy-Fuel Combustion
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