Carbon Burnout Research Articles

Multiple thermal resistance induced extremely low thermal conductivity in porous SiC-SiO2 ceramics with hierarchical porosity

Maximizing interfaces for blocking heat conduction in porous ceramic structures is an efficient approach for achieving maximum thermal resistance. Here, we adopted three strategies simultaneously for maximizing thermal resistance in porous SiC-based ceramics: (1) addition of nano-sized silica into nano-sized SiC powder for generating SiC/SiO2 interfaces, (2) addition of nano-sized carbon into nano-sized SiC powder as the template, and (3) sintering in air, which leads to the partial oxidation of the nano-sized SiC particles and burn-out of nano-sized carbon, giving rise to the generation of the SiC-core/SiO2-shell structure and formation of micro-, meso-, and macro-sized pores. The thermal conductivity, compressive strength, porosity, and specific compressive strength of porous SiC-SiO2 ceramics processed at 600 °C with the above strategies were 0.066 Wm−1 K−1, 2.7 MPa, ∼72 %, and 3.9 MPa·cm3/g, respectively.

Oxidation of Dibenzothiophene in Water Vapor and Argon at Increased Pressure

This article presents the results of study of dibenzothiophene (DBT, the fuel equivalence ratio $$\varphi = 0.94$$ –1.01) oxidation in a medium of dense water vapor or argon at uniform heating (1 K/min) to 853 K of a tubular reactor made of stainless steel. The oxidation of DBT was found to proceed by the mechanisms of heterogeneous and homogeneous reactions. From the dynamics of the temperature of the reaction mixtures it follows that self-ignition of DBT in an environment of water vapor and argon occurs at 532 K. A Pt-Rh/Pt thermocouple introduced into the center of the reaction volume was found to have a catalytic effect on DBT oxidation. The results of mass spectrometry analysis of gas products show that the degree of carbon burnout exceeds 95% mol. The interaction of stainless steel and H $$_{2}$$ SO $$_{4}$$ formed in the DBT oxidation in water vapor causes steel corrosion, which is suppressed due to neutralization of the acid by calcium carbonate. The composition of the corrosion products was determined by the X-ray diffraction and energy-dispersive analysis methods.

Influences of initial coal concentration on ignition behaviors of low-NOx bias combustion technology

In order to provide the key parameters of initial coal concentration to low-NOx bias combustion technology and enrich the pulverized-coal bias combustion theory, pilot-scale ignition experiments of bias coal streams were carried out using a 250-kW fuel input bias combustion facility. The experimental results including combustion temperature, unburned residues, gas species, and flame spectra were collected. The influences of initial coal concentration on the ignition behaviors of an Indonesian subbituminous in a reducing atmosphere were studied. Our findings show that as initial coal concentration increased, the intensity of visible light and the carbon burnout progressively increased, while the ignition distance and the fuel NOx formation continually decreased. It was observed that the region of continuous flame became successively concentrated, and the flame stability was increasingly enhanced, indicating that the ignition behaviors improved in a gradual way. Furthermore, the mechanism of the combined homo-heterogeneous ignition changed to homogeneous ignition. To be specific, at initial coal concentrations of 0.33 kg/kg and 0.41 kg/kg, the homo-heterogeneous combined ignition mechanism occurred. While at an initial coal concentration of 0.53 kg/kg, the mechanism changed to homogenous ignition. For a tangentially-fired pulverized-coal boiler burning the Indonesian subbituminous, the highest initial coal concentration of the horizontal bias combustion burners can be designed as 0.53 kg/kg, which will be beneficial to the strong ignition and low-NOx emission.

Experimental investigation on the ignition and combustion characteristics of pyrolyzed char and bituminous coal blends

This work studies the ignition behavior and combustion characteristics of pulverized pyrolyzed bituminous (PB) char blended with pulverized bituminous coal at different mass fractions. Experimental studies were conducted with OH planar laser-induced fluorescence (OH-PLIF) diagnosis technology in a flat-flame optical entrained flow reactor for pulverized coal/char. An interaction occurs between pyrolyzed char and bituminous coal, which is indicated by the relationship observed between the pyrolyzed char mass fraction mean values (MFMVs) and the combustion properties of the blended fuels. The addition of bituminous coal enhances the competitive effects of the two fuels on ignition and burnout. The synergistic effect observed upon ignition of the blends is mainly attributed to the high volatile contents and the potential catalysis effects from the alkali and alkaline earth metal species in the blends. The important factor leading to this synergistic effect is that the alkali and alkaline earth metal species in the ash can reduce the ignition temperature and accelerate the release of volatiles, thereby shortening the ignition delay. The high flame temperature and the potential catalysis effects from the alkali metal and transition metal species promote blended fuel burnout. Considering both the ignition delay and the residual char burnout, the optimal blending ratio of pyrolyzed char is approximately 20% because the fixed carbon burnout of the blends is considerably promoted and the ignition delay is significantly shortened. In comparison with PB char, the ignition delay decreased by 28.95% and the burnout ratio increased by 39% at the 20% PB char blending ratio.

Cleaner crude oil combustion during superheated steam atomization

Crude oil is an attractive fuel for energy production, since its use does not require additional processing costs. Existing technologies for burning liquid fuel do not always ensure the achievement of the modern ecological and energy performance when using highly viscous and substandard fuels. This relates to unstable ignition and combustion of such fuels in the combustion chamber, relatively fast coking of the burner surfaces, etc. The work deals with investigation of crude oil burning in a flow of superheated steam as a promising way to reduce NOx and increase the completeness of fuel combustion. The experiments were carried out using an original burner where liquid fuel is sprayed due to interaction with a high-velocity flow of superheated steam. This method of spraying allows the creation of a highly dispersed two-phase flow and prevents nozzle chocking and coking when using sub-standard fuel and waste. At the same time, steam gasification of products of fuel thermal decomposition allows the reduction of toxic emissions, increasing carbon burnout. The regimes of crude oil burning in a modernized burner that provide high completeness of fuel combustion (~44 MJ/kg) with a low content of NOx and CO in the combustion products have been determined. The amount of these toxic components corresponds to class 1 of EN 267. The results obtained confirm the effectiveness of the investigated method of fuel spraying by a superheated steam jet for environmentally friendly crude oil burning, including this process in the low-power burners (~15 kW). Such devices can be used for the cleaner elimination of liquid hydrocarbon waste with the receipt of thermal energy.

Effects of pyrolyzed semi-char blend ratio on coal combustion and pollution emission in a 0.35 MW pulverized coal-fired furnace

The effects of blend ratio on combustion and pollution emission characteristics for co-combustion of Shenmu pyrolyzed semi-char (SC), i.e., residuals of the coal pyrolysis chemical processing, and Shenhua bituminous coal (SB) were investigated in a 0.35 MW pilot-scale pulverized coal-fired furnace. The gas temperature and concentrations of gaseous species (O2, CO, CO2, NOx and HCN) were measured in the primary combustion zone at different blend ratios. It is found that the standoff distance of ignition changes monotonically from 132 to 384 mm with the increase in pyrolyzed semi-char blend ratio. The effects on the combustion characteristics may be neglected when the blend ratio is less than 30%. Above the 30% blend ratio, the increase in blend ratio postpones ignition in the primary stage and lowers the burnout rate. With the blend ratio increasing, NOx emission at the furnace exit is smallest for the 30% blend ratio and highest for the 100% SC. The NOx concentration was 425 mg/m3 at 6% O2 and char burnout was 76.23% for the 45% blend ratio. The above results indicate that the change of standoff distance and NOx emission were not obvious when the blend ratio of semi-char is less than 45%, and carbon burnout changed a little at all blend ratios. The goal of this study is to achieve blending combustion with a large proportion of semi-char without great changes in combustion characteristics. So, an SC blend ratio of no more than 45% can be suitable for the burning of semi-char.

Strategic combustion technology with exhaust tube vortex flame: Combined effect of biomass co-firing and air-staged combustion on combustion characteristics and ash deposition

A 16-kWth coal-fired furnace with a dual swirl burner was constructed to investigate the combustion characteristics with/without an exhaust tube vortex (ETV) flame, the combined effect of ETV flame and air staging on pollutant emissions, and the carbon burnout performance. The without ETV flame was more favorable than those of with ETV flames in terms of NO emission. However, its CO emission was primarily higher than those of with ETV flames. Through the correlation between pollutant emissions and carbon burnout, it was confirmed that the case with ETV flame exhibited higher stability than that without ETV flame. Consequently, the ETV flames have a positive effect on carbon burnout performance at every air staging level. In addition, the effects of woody biomass co-firing ratios with ETV flame were evaluated according to pollutant emissions and combustion characteristics, as well as ash deposition using scanning electron microscopy-energy dispersive spectroscopy. The increase in woody biomass co-firing ratio exhibited a positive effect on the NO and unburned carbon reduction. The air-staged combustion was more favorable than the unstaged combustion in terms of NO reduction and ash deposition. Air-staged combustion technology should be applied to reduce ash deposition at the co-firing ratio of 20% or more.

Development of information modeling system of coal-dust fuel injection into tuyeres of blast furnace

The article considers a mathematical model of combustion zone of blast furnace working with the use of injection of coal-dust fuel. In this model, two subsystems were identified: 1) subsystem of heating the particles of coal dust and volatiles release in the combustion zone; 2) subsystem of heat exchange and combustion processes in the tuyere. A two-dimensional velocity field of gas in the combustion zone was investigated. The combustion processes are considered as a set of simultaneously developing phenomena of coke burning in a layer, single pieces of coke and particles of coal dust. The model includes following equations: total gas mass balance, gas component mass balance, gas heat balance, movement of coal dust particles and heat balance of coal dust particles. The model calculates maximum burning temperature in combustion zone; the distance from the cut of the tuyere to the focus of combustion; the length of the oxygen combustion zone; gas temperature; the content of gas phase components and the degree of carbon burnout of pulverized coal at the outlet of the tuyere combustion zone. Information-modeling system has been developed. It allows investigation of influence of combined blast characteristics, the properties of coke and coal-dust fuel, the geometric dimensions of tuyeres and other factors on temperature fields and concentrations of components of gas phase in combustion zone. The model also helps to select a rational mode of pulverized coal that will ensure completeness of its combustion in the tuyere combustion zone. Main functions of the program are as follows: representation of results of calculation in form of tables and diagrams, storage of options of basic data in a database and export of results of calculation to Microsoft Excel. Conclusions were made on reduction of combustion temperature in combustion zone and the approach of focus of combustion to the tuyere when pulverized coal was injected. The authors also have established the need to use coals with certain quality characteristics and place where coal dust was introduced into the blast stream.

Development of an Information Modeling System of Coal-Dust Fuel Injection into Tuyeres of a Blast Furnace

The article considers a mathematical model of the combustion zone of a blast furnace working with the use of the injection of coal-dust fuel. In this model, two subsystems were identified: (1) subsystem of heating the particles of coal dust and volatiles released in the combustion zone; (2) subsystem of heat exchange and combustion processes in the tuyere. A two-dimensional velocity field of gas in the combustion zone was investigated. The combustion processes are considered as a set of simultaneously developing phenomena of coke burning in a layer, single pieces of coke and particles of coal dust. The model includes the following equations: total gas mass balance, gas component mass balance, gas heat balance, movement of coal dust particles, and heat balance of coal dust particles. The model calculates maximum burning temperature in the combustion zone, the distance from the cut of the tuyere to the focus of combustion, the length of the oxygen combustion zone, gas temperature, the content of gas phase components, and the degree of carbon burnout of pulverized coal at the outlet of the tuyere combustion zone. An information-modeling system has been developed. It allows for the investigation of the influence of combined blast characteristics, the properties of coke and coal-dust fuel, the geometric dimensions of tuyeres, and other factors on the temperature fields and concentrations of components of the gas phase in the combustion zone. The model also helps to select a rational mode of pulverized coal that will ensure completeness of its combustion in the tuyere combustion zone. The main functions of the program are as follows: representation of results of calculation in form of tables and diagrams, storage of options of basic data in a database, and export of results of calculation to Microsoft Excel. Conclusions were made on the reduction of the combustion temperature in the combustion zone and the approach of the focus of combustion to the tuyere when pulverized coal was injected. The authors also have established the need to use coals with certain quality characteristics and place where coal dust was introduced into the blast stream.

Electric arc synthesis of titanium carbide nanoparticles

The structure of titanium carbide nanoparticles formed at electric arc spraying of composite Ti-C electrodes is studied. It is shown that the size of titanium carbide particles in condensation products varies in the range of 10–50 nm, crystal lattice of nanoparticles corresponds to TiC carbide. Annealing the material in an oxygen-containing atmosphere leads to carbon burnout and oxidation of titanium carbide nanoparticles. The main part of carbon is oxidized in the temperature range of 250–500°C, oxidation of titanium carbide nanoparticles occurs in the range from 320 to 400°C. When annealed to the temperatures of 1000°C, sintering of oxide TiO2 nanoparticles occurs. The proposed method can be used to obtain particles of titanium carbide with a shape close to the TiC crystal.

Effect of exhaust tube vortex on NOx reduction and combustion characteristics in a swirl-stabilized pulverized coal flame

Experimental investigations were conducted on the effect of the exhaust tube vortex (ETV) and the synergistic effect of the ETV and air staging on nitrogen oxide (NO) concentration and carbon monoxide (CO) concentration, as well as carbon burnout in a swirl-stabilized pulverized coal-fired furnace. To elucidate the aforementioned effects, four different swirl combinations were prepared derived from co-swirl and counter-swirl through five staging air injection positions. The results show that the ETV contributes to unburned carbon (UBC) combustion through its hollow-tube structure in the co-swirling flame. In addition, the temperature is distinguishable in the case of the 60°–60° co-swirl combination (Sco, 1.37/1.50), and 60°–60° counter-swirl combination (Sct, 1.37/1.50) because of the shape of the inner recirculation zone (IRZ) and the occurrence of the ETV. Although the ETV effect follows the swirl intensity, the 50°–50° co-swirl combination (Sco, 0.95/1.03) is the most favorable for the ETV effect under the unstaged condition, considering the behavior of the burner aerodynamics that contains the IRZ and the flame propagation dependent on the swirl vane angle. The result without an ETV is reflected in Sct, 1.37/1.50, meaning incomplete combustion of the coal during the combustion procedure. In terms of the synergistic effect, NO and CO reduction rates, as well as carbon burnout are needed to evaluate the best overall performance. According to evaluation, Sco, 1.37/1.50 at staging level 3 (SL3) has the highest synergistic effect because the effect of air staging is maximized in SL3 given the longest particle residence time in the re-burning zone.

Study on the Influence of the Activation Energy on the Simulation of Char Combustion

The numerical simulation of coal char combustion process can quickly obtain the combustion characteristics of char. It has guiding significance for the design and operation industrial boilers. But during the numerical simulation, how to choose the appropriate kinetic parameters is a difficult problem. The values of combustion activation energy in previous literatures were different. This paper focused on the influence of activation energy on the simulation results of char combustion. The activation energies of 20 Chinese typical coals were measured by a two-step in-situ reaction analyzer. CBK (Carbon burnout kinetics) model was used to simulate char combustion process. Results showed that when activation energy varied greatly, the the predicted combustion rate and particle temperature were very different, especially in the later stage of char combustion.

Porous alumina ceramics by gel casting: Effect of type of sacrificial template on the properties

AbstractThe effect of type of sacrificial template on the processing and properties of porous alumina ceramics was investigated. Two templates, (a) hollow pre‐expanded polymer spheres (Expancel) and (b) dense glassy carbon, were used to prepare porous alumina ceramics by gel casting. The results showed that the burnout of sacrificial expandable polymer microspheres from alumina ceramics was 10 times faster than glassy carbon without compromising the compressive strength. Moreover, the effect of the size of the porous ceramic component during the burnout showed that the template decomposition and the escape of the formed gases took a longer time for the thicker specimens than the thinner one and it was significant in case of glassy carbon. It was found that the burnout of expandable microspheres could happen at a faster rate, and the time of the burnout cycle could be reduced significantly to save energy while keeping the mechanical strength twice as high than porous alumina ceramics after burnout of glassy carbon. Furthermore, the CO2 emissions during the burnout of sacrificial templates and the microstructure of the prepared porous alumina were compared for these two types of sacrificial templates. The prepared foams with pre‐expanded microspheres showed potential for being used in industrial applications, where the decreasing of the released gases is critical for saving time and energy for the fabrication of large ceramic parts.

Influence of biomass blends on the particle temperature and burnout characteristics during oxy-fuel co-combustion of coal

The difference in combustion performance between brown coal and black coal blended with Eucalyptus woodchip and woodchar in varying blending ratios were examined in the air and oxy firing conditions. On top of the experimental investigation using a drop tube furnace (DTF), a computational fluid dynamics (CFD) model was further developed to interpret these results, validated using the experimental data. The CFD model incorporates a comprehensive reaction for devolatilisation reaction to predict the gas release utilising predictions based on chemical percolation devolatilisation (CPD) model. The heterogeneous reactions are defined based on the intrinsic reaction model that accounts for the influence of char properties in chemical and pore diffusion reactions using a user-defined function (UDF). Moreover, the C–CO2 gasification reaction rate which is critical in an oxy-firing mode was further studied using the CFD tool to determine how the role of gasification varied for various fuel blends. Based on carbon burnout and average particle temperature profiles, the blending of woodchips is highly beneficial to the overall combustion performance in particular for low reactive black coal while its effect on brown coal is marginal. Woodchar and black coal are comparable with similar temperature plots and relatively constant burnout but it behaves relatively inert with a highly reactive brown coal. During oxy firing, increasing the woodchip content enhanced the effect of C–CO2 gasification due to its extremely large pre-exponential factor for the CO2 gasification reactivity which explains the improved burnout. The blending of woodchar caused a gradual reduction in the gasification extent for both coals explained by the low heating rates under which woodchar was pyrolysed and also due to the decrease in the peak particle temperature. However, the observed gasification was found to be less than the expected value based on the linear addition of the two single fuels for both biomass blends.

A thermofluid network based methodology for integrated system simulation of heat transfer and combustion in a coal-fired furnace

Coal-fired power plant boilers are made up of several complex and interdependent subsystems that all need to work together properly to ensure plant availability, efficiency and safety, while limiting emissions to the environment. Having a process model where the relevant subsystems are coupled, and the interdependencies can be ascertained, is therefore invaluable. Such an integrated model may be based on a one-dimensional thermofluid network approach to model the water to steam cycle and the coal and air to flue gas cycle. If quick solution times are required, for instance in model based on-line process condition monitoring, such an integrated model cannot capture the same level of detail that would typically be available in a three-dimensional CFD model. However, even in a reduced model a three-dimensional approach may be required, for instance when modelling the thermal radiation heat transfer in the furnace. This paper proposes a network based methodology which combines the zonal method to model the radiation heat transfer in three dimensions with a one-dimensional burnout model for the heat generation, and characteristic flow maps for the mass transfer. The methodology was applied to the single burner furnace of the IFRF’s experimental facility at Ijmuiden in the Netherlands, for which extensive empirical data is available. The new model was used to predict the radial temperature profile near the furnace exit and the heat absorbed through the walls, as well as the temperature, carbon burnout, oxygen and carbon dioxide profile along the centerline of the furnace. To better understand the benefits and limitations associated with the specific combination of models implemented here, a CFD model was also developed and used for comparison. The results obtained with the new model compare well with the CFD benchmark, as well as the experimental results. This provides confidence that the combination of models applied here can be used to model the integrated behavior in the single burner furnace and forms the basis for expansion to utility scale boilers.

Experimental Investigation of NO Reburning During Oxy-Coal Burner Staging

This study presents an investigation into the impact of varied burner staging environments on an oxy-fuel flame and the rate of the NO formation and destruction processes. The experimental data were extracted from the use of a 250 kWth down-fired combustion test facility with a scaled-down model of an industrial low-NOx burner. Two oxy-coal combustion regimes were investigated by varying a fixed flow of oxidant between the secondary and tertiary registers, so as to impact the stoichiometry in the fuel-rich region and flame structure, and using various NO recycling regimes, to test the impact of these different burner configurations on NO reburning. The data were collected by monitoring key emissions in the flue gas and in the flame, as well as temperatures throughout the furnace and the unburned carbon content of the ash. A detailed investigation encompassing the impact of secondary oxidant proportion for different oxidants on NO emissions, together with the quantification of recycled NO destruction, is discussed. This investigation finds that 85–95% of the recycled NO is destroyed at a range of burner configurations using OF 27 and OF 30 at 170 kWth. In addition to this, NO formation and carbon burnout are found to be significantly affected with changing burner configurations. Further to this, OF 30 flames appear to be more sensitive to burner configuration than OF 27 flames with regards to both NO formation and destruction, possibly due to the decreased density of the OF 30 oxidant. Radial profiles of two burner configurations at OF 27 and OF 30, as well as an axial profile of two burner configurations at OF 30, were analyzed. The profiles appear to show that burner staging aids in controlling the products of NO reburning, hence maximizing the destruction of recycled NO.

A full spectrum k-distribution based non-gray radiative property model for unburnt char

By using the concept of weighted sum of four gray particles and spectrum k-distribution (WSGP-SK), a non-gray radiative property model for unburnt char particles is developed. Based on the carbon burnout kinetic model for structure during oxidation, and the linear mixed approximation theory for complex index of refraction, spectral radiative properties of unburnt char particles are first calculated as function of the burnout ratio by Mie theory. Referring to the full spectrum k-distribution model, k-distribution is applied to reorder absorption and scattering efficiencies of particles. Then, weighting factors and efficiency factors of the non-gray radiative property model are directly obtained from Gaussian integral points of k-distribution. The model is validated against the benchmark solutions of line-by-line (LBL) model. Maximum relative errors of this model are 3% and 15% for radiative heat fluxes and source terms in non-isothermal inhomogeneous particulate media, respectively. The assumption of linearly varying radiative properties with burnout ratio (Lockwood et al. 1986) will result in a predicted deviation of 53% for radiative source terms. Results also show that this non-gray model is remarkably better than the Planck mean method. Moreover, a satisfactory comparison with LBL solutions is achieved in the gas and particle mixture by combining the non-gray WSGG-SK model (Guo et al. 2015). As a radiation sub-model, this non-gray radiative property model can significantly improve prediction accuracy of radiative heat transfer in oxy-fuel combustion.

Effect of rice husk co-combustion with coal on gaseous emissions and combustion efficiency

ABSTRACTInvestigation on co-combustion of Lakhra coal and rice husk blends was carried out in a drop tube furnace to measure its impact on flue gas emissions and carbon burnout. According to experimental results, the emissions of NO and SO2 were higher in case of combustion of Lakhra coal compared to coal​–rice husk blends combustion. The emissions of CO decreased rapidly at higher furnace temperatures beyond 900°C. Minimum of CO emissions were nearly 45 ppm while SO2 and NO emissions were found to be 554 and 120 ppm, respectively, for 15% biomass blending ratio and at exit furnace temperature of 1000°C. The unburnt carbon was found to be reduced significantly with an increase in furnace temperature and blending ratio. The study has shown that blending of rice husk would be a useful option to minimize SO2 and NO emissions during combustion of Lakhra coal.

Porous ceramics with a duplex pore structure by compression molding of alumina-NaCl paste in molten sucrose

Abstract Alumina-NaCl pastes in molten sucrose were prepared by hot blending of alumina-NaCl-sucrose mixtures at a fixed alumina powder to sucrose weight ratio of 1:1 and NaCl to alumina powder weight ratios in the range of 0.6–1. The pastes compression molded at 160 °C for 2 h set due to the caramelization of the molten sucrose. The NaCl and alumina catalyzed the caramelization of molten sucrose as evidenced from the torque-time measurements. The compression molded bodies on carbonization followed by salt removal by leaching with water, carbon burnout and sintering produced porous alumina ceramics with a duplex pore structure. The carbon produced from the sucrose effectively bound the alumina particles which prevented the disintegration of the green body during NaCl removal. Macropores (48–71 µm) were created by the water vapour produced by –OH condensation during setting by caramelization and the microcells (0.7–8 µm) were formed by the removal of NaCl templates. The porosity of the alumina ceramics increased from 59 to 71 vol% whereas the compressive strength decreased from 59.2 to 11.7 MPa when the NaCl to alumina powder weight ratio increased from 0.6 to 1.

Porous acicular mullite ceramics fabricated with in situ formed soot oxidation catalyst obtained from waste MoSi2

Abstract Porous acicular mullite (3Al2O3·2SiO2) ceramics containing Cu3Mo2O9 as a soot oxidation catalyst was fabricated by a novel approach using commercial powders of Al2O3 and CuO, and powder obtained by controlled oxidation of ground waste MoSi2. The obtained material consisted of elongated mullite grains which are known to be effective in carbon soot removal from diesel engine exhaust. The presence of in situ created Cu3Mo2O9 was found to catalyze the carbon burnout which is an extremely important feature when it comes to filter regeneration, i.e., the captured soot removal. The carbon burnout temperature in the sample containing 12 wt% CuO was by 90 °C lower than that in the sample without CuO. Effect of sintering temperature as well as the effect of amount of CuO additive on mullite properties were studied. It was found that the increase in amount of CuO in samples sintered at 1300 °C decreased porosity and increased compressive strength of the porous mullite ceramics. The addition of 12 wt% CuO increased the strength of the porous mullite ceramics up to 70 MPa, whereas the porosity was reduced from 62% in the mullite without CuO to 44% in the mullite ceramics containing 12 wt% CuO. Although affected by the amount of CuO, the microstructure still consisted of elongated mullite grains.