Flue Gas Analyzer Research Articles

Theoretical Proposal for a New Model of Cylindrical Biogas Combustion Cook Stove

<p>The cook stove is usually constructed from black-painted sheet metal, to better absorb energy. To enhance thermal performance, a theoretical cylindrical design is proposed in this article. This article aims to study this design and compare its performance with the conical design. Theoretical modeling of the cook stove was carried out considering heat transfer by radiation, convection, and conduction based on a steady-state thermal network, and solved using the Matlab R2021b<sup>®</sup> platform under license (License No. 595687). The result of the theoretical analysis predicts a theoretical efficiency of 65%, a pot air temperature <em>T<sub>f</sub></em>=220<sup>o</sup>C and a flame temperature <em>Ta</em>=900<sup>o</sup>C. Similarly, a validation with Sagouong's model on combustion chamber temperature and Kaushik's model on thermal efficiency. A maximum threshold (RMSE) of 4% is observed between the two studies. The <em>T<span style="font-size: 8.33333px;">c</span></em> temperature stagnates rapidly within 5 minutes at 600<sup>o</sup>C and the comparison showed that the firing temperatures of the cylindrical shape are higher than those of the conical-shaped cook stove. Consequently, the performance of the cylindrical-shaped cooking stove can be improved by further experimentation and flue gas analysis.</p>

Kömür Yakıcılarında Yanma Verimi Tahmini için Gömülü Platformda Çalışabilen Evrişimsel Sinir Ağının Parametre Analizi

Accurately and effectively calculating combustion efficiency in coal burners is crucial for industrial boiler manufacturers. Two main approaches can be used to calculate boiler efficiency: 1) Analyzing the gas emitted from the flue; 2) Visualizing the combustion chamber in the boiler. Flue gas analyzers, which are not user-friendly, come with high costs. Additionally, the physical distance between the flue and the combustion chamber causes the measurement to be delayed. Methods based on visualizing the combustion chamber do not have these disadvantages. This study proposes a system based on visualizing the combustion chamber and has two contributions to the literature: 1) for the first time, the modern Convolutional Neural Networks (CNN) approach is used to estimate combustion efficiency; 2) the CNN architecture with optimal parameters can work on an embedded platform. When classical classification techniques and a CPU-supported processor card are used, efficiency can be calculated from one flame image in 1.7 seconds, while this number increases to approximately 20 frames per second (34 times faster) when the proposed CNN architecture and GPU-supported processor card are used. The results obtained demonstrate the superiority of the proposed CNN architecture and hardware over classical approaches in estimating coal boiler combustion efficiency.

Analysis of Carbon Particulate Matter Removal Performance of Dual-Fuel Marine Engine with DOC + CDPF

This study analyzes Diesel Oxidation Catalyst (DOC) and Carbon Diesel Particulate Filter (CDPF) after-treatment systems integrated into a WARTSILA W20DF marine dual-fuel engine. The CDPF was coated with a non-precious metal catalyst whose catalytic redox performance improved with increasing temperature. The carbon particulate matter combustion reached up to 12.5 mg/s at 800 K and over 20 mg/s at 900 K. Then, the W20DF running at 230 kW, 450 kW, 680 kW, and 810 kW with 1000 rpm; a Tisch 10-8xx; and an AVL SPC 478 were used to sample and analyze the carbon particulate matter (CPM) before and after DOC + CDPF. The gaseous emissions (O2, CO2, CO, HC, NOx, and NO2) were analyzed with the flue gas analyzer AVL i60. The results show that the collected carbon particulate matter simultaneously became darker as the load decreased. This study finds that the maximum amount of CPM per unit volume of exhaust gas occurs under 50% working conditions and the lowest amount under 90% working conditions. After DOC + CDPF treatment with a non-precious metal coating, the CPM was reduced by about 50%. Furthermore, this type of catalyst’s efficiency rises with the temperature increase. The CPM combustion efficiency reached up to 20 mg/s at 900 K. The other gas components in the exhaust gas before and after DOC + CDPF also changed. These research results have a significant reference value for DOC + CDPF optimization to decrease the carbon particulate matter in marine engines.

Effect of preheating Co-firing of biomass and coal on the synergistic reduction of PM and NO source emissions

Co-firing of biomass and coal is a prevalent method in modern thermal power plants to reduce pollutant emissions. This study focuses on the preheating co-firing behavior of coal and biomass to explore the effect of preheating combustion and preheating co-firing on PM (particle matter) and NO source emissions, and different coals were selected to verify the effect of coal rank on this behavior. Coal and biomass were fed into a mixing device through two independent feeders and uniformly mixed before entering the furnace. PM and NO emissions after preheating combustion were measured using an Electrical Low-Pressure Impactor and flue gas analyzer. The results showed that preheating combustion reduced the production of PM1, PM1-10, and NO from coal by 22.30%, 10.75%, and 49.84% respectively, and also reduced the production from biomass by 28.61%, 15.16%, and 53.01% respectively compared to conventional combustion. Preheating co-firing experiments revealed that as the co-firing ratio increases, NO production decreased, but the production of PM1 initially decreased and then increased, reaching a minimum point at a co-firing ratio of 25%. Meanwhile, the lower the rank of the coal, the better the effect of preheating combustion and preheating co-firing, and the ash content and composition of coal also had an impact on the generation of PM1.

Impact of crude palm oil on engine performance, emission product, deposit formation, and lubricating oil degradation of low-speed diesel engine: An experimental study

The higher emissions are one of the main issues associated with the use of diesel power plants. Therefore, various previous studies have been conducted on the substitution of diesel with renewable base liquid fuels for internal combustion engines, such as Crude Palm Oil (CPO). In this study, a comprehensive evaluation was carried out on the impact of using CPO on a low-speed diesel engine with a large capacity. The objective of this study is to determine the viability of modifying the existing diesel engine to operate on CPO fuel, with the aim of minimizing the requirement for additional capital expenditures. Furthermore, a diesel power plant engine with a rated capacity of 2554 kW and a rated speed of 600 RPM using a modified injector was employed. The testing phase was divided into two stages namely, a performance test for 7 h and a running test for 375 h. During the running test, the level of emission was also tested with different load variations using a portable flue gas analyzer. Following this, the lubrication oil sample was collected both before and after the engine running test. The deposits sample obtained from the engine was analyzed using SEM-EDX. Prior to being introduced into the engine, the fuel pre-treatment plant ensured that the kinematic viscosity and temperature of the CPO were properly maintained. The results show that operating the low-speed diesel engine with the continuous use of 100% CPO is not recommended due to the reducing of the engine gross power, the peak combustion pressure, the engine's IHP (indicated horse power) and the exhaust temperature of each cylinder. Furthermore, deposits were found on the cylinder head, piston, valve, and nozzle. Besides, the lubricating oil quality also degraded. Therefore, necessary to conduct a comprehensive study on the technical and financial aspects of using other biofuels that have a minimal risk impact on engine reliability and performance as an alternative to diesel or biodiesel fuel in low-speed diesel power plants.

Effect of microsecond repetitively pulsed discharges on lean blow-off limit and emission of rapidly-mixed ammonia/air swirling flames

This work aims to implement an actuator integrating a swirl burner with electrodes to explore stable and low-emission combustion of ammonia/air. The cavity structure holds a plasma torch driven by low-power microsecond repetitively pulsed discharges (µRPDs) in the nozzle, which serves as a pretreatment for ammonia/air gas before it enters the combustion region. The plasma generates strong excited N2, OH, and atomic H* and O* signals, and fitting N2 spectra indicates a rotational temperature of ∼3000 K and vibrational temperature of ∼4500 K. The flame without plasma is easier to detach from the wall and operate as a cone-shaped structure in the confined quartz tube, while plasma can help attach the flame and extend the lean blow-off limit from ∼0.6 to 0.4∼0.5 in a Reynolds number range of ∼3000 to 7500. Then, optical diagnostics for OH radical and NH2* chemiluminescence are performed to enable analysis of intermediate chemistry. The NH2* signals are distributed at the edge of the OH profile in both attachment and detachment cases. Finally, flue gas analyzers are used to find an optimal lean equivalence ratio where plasma anchors a stable ammonia/air flame with a relatively low emission of approximately 200 ppm NO and zero NH3 and H2.

Application of a Robust Thermoelectric Gas Sensor in Firewood Combustion Exhausts

The quality of wood combustion processes can be effectively improved by achieving the automated control of the combustion air feed. For this purpose, continuous flue gas analysis using in situ sensors is essential. Besides the successfully introduced monitoring of the combustion temperature and the residual oxygen concentration, in this study, in addition, a planar gas sensor is suggested that utilizes the thermoelectric principle to measure the exothermic heat generated by the oxidation of unburnt reducing exhaust gas components such as carbon monoxide (CO) and hydrocarbons (CxHy). The robust design made of high-temperature stable materials is tailored to the needs of flue gas analysis and offers numerous optimization options. Sensor signals are compared to flue gas analysis data from FTIR measurements during wood log batch firing. In general, impressive correlations between both data were found. Discrepancies occur during the cold start combustion phase. They can be attributed to changes in the ambient conditions around the sensor housing.

Preparation of CFB fly ash/sewage sludge ceramsite and the morphological transformation and release properties of sulfur

In order to improve the resource utilization of circulating fluidized bed (CFB) fly ash and sewage sludge, light-weight and high-strength CFB fly ash/sewage sludge ceramsite (CFBS ceramsite) was prepared by using CFB fly ash and original wet sludge as the main raw materials. The effects of dosages of CFB fly ash, sewage sludge, fluxing agent, and foaming agent and sintering temperature on the physical and mechanical properties of CFBS ceramsite were studied by single factor experiment method. Using SEM, XRD, sulfur analyzer, TG-DSC, flue gas analyzer, TG-MS and XPS analyses, the micro morphology and mineral composition of CFBS ceramsite were studied, and the morphological transformation and release properties of sulfur were also revealed. The results show that the optimal preparation conditions are: the mass ratio [CFB fly ash: sludge] = [65 %∼80 %: 35 %∼20 %], addition of 10 % glass powder, addition of 2.5 %∼10 % calcium carbonate, and sintering at 1200 ∼ 1250℃ for 15 ∼ 20 min. The resulting CFBS ceramsite can be obtained with bulk density of 750 ∼ 850 kg/m3, water absorption of 0.27 %∼0.94 % and cylinder compressive strength of 5.11 ∼ 7.86 MPa. Sulfur in the CFBS ceramsite is mainly derived from organic sulfur in the sewage sludge and inorganic sulfur in the CFB fly ash, and it exists in the form of sulfate and sulfide when the sintering temperature exceeds 400℃. The sulfur content of the final prepared CFBS ceramsite is 0.0217 wt%. Decomposition of SO2 from the anhydrite in CFB fly ash is the main reason for the swelling and foaming of the CFBS ceramsite. However, calcium carbonate, derived from either sulfur-fixing agent in CFB fly ash or auxiliary foaming agent, cannot play the role of foaming agent, while the CaO decomposed from calcium carbonate increases the content of fluxing component in the ceramsite and finally affects the properties of CFBS ceramsite.

The Effect of CaO on the CO and NOx Emission Characteristics of Fast-Growing Grass Combustion

Fast-growing grass is a biomass material with characteristics such as high temperature and drought resistance; rapid growth and development; and repeated germination and cutting. Therefore, it is a popular biomass fuel. It is required that the pollutants produced during the biomass combustion process are appropriately controlled. For this purpose, our study analyses the influence of combustion temperature and calcium oxide (CaO) on the nitrogen oxides (NOx) and carbon monoxide (CO) emission characteristics of fast-growing grass combustion using the biomass combustion flue gas analysis and testing platform. The results of our analysis revealed that CaO additive can simultaneously reduce the peak and total NOx emissions at 750 °C. Particularly, 5% CaO demonstrated a significant control effect on the NOx emission from the fast-growing grass combustion process, with a peak and total emissions reduction of 47.05% and 56.81%, respectively. In addition, with an increase in temperature, the CO emission curve attains a second peak higher than the first peak, and the peak and total emissions show a decreasing trend.

Pure oxygen condition forced oxidation ignition process of underground coal gasification

AbstractUnderground coal gasification without shaft is a technology that uses directional drilling technology to gasify deeply buried coal. The technology first needs to ignite the coal seam during drilling, but as the depth of the coal seam (drilling) increases, it is very difficult to ignite the underground coal seam. In order to ignite the underground coal seam more safely and effectively, the forced oxidation ignition technology has been developed; that is, the coal seam is heated by hot oxygen, and the coal seam is rapidly oxidized and released to ignite the coal seam. Due to the complex confidential environment, it is challenging to ignite underground coal seams. To ignite the underground coal seams more safely and effectively, this paper used a self‐made reactor to simulate the forced convection heating of the bituminous coal under different oxygen flow rates with hot oxygen and used a Fourier transform infrared spectrometer flue gas analyzer to detect the outlet gas, used ATR‐FTIR spectrometer to analyze the solid residues in different areas, and recorded the time and maximum temperature of coal ignition under other processes. The results showed that low‐flow high‐temperature oxygen could quickly burn coal seams. When the oxygen flow rate was 2.5 m3/h, and the coal seam was ignited when heated to 130°C for 170 min. Through GC‐MS analysis of nine flammable components in the tar components under different processes, the content of short‐chain aliphatic hydrocarbons in the tar decreases, and the content of benzene series tends to increase. Through ATR‐FTIR analysis, the solid sample near the gas injection port contained fewer oxygen functional groups; the middle of the furnace body included the most oxygen functional groups; near the gas outlet contained more oxygen functional groups than the raw coal. CO2 would rise to 3% when coal was about to ignite.

Estimating the chemical composition of municipal solid waste using the inverse method

This research aims to perform and implement an inverse solution method in waste-to-energy power plants for carrying out solid waste analysis without sampling. For this purpose, a simple simulated experiment is defined to evaluate the stability and accuracy of the method, which is investigated by adding random errors to the results of the direct problem conducted by the Monte Carlo method. The inverse problem solution procedure is solved by obtaining data categories for measuring parameters. In addition, the coefficient matrix is created and the linearization method is employed. By assuming a 0.5 percent nitrogen content in municipal solid waste, the number of unknown parameters is reduced, and the problem is solvable. The regularization method is applied to obtain the stability of the answer. The procedure is done for a municipal solid waste analysis with different regularization parameters. The mean value error and variance of the obtained solution from each analysis are evaluated and the acceptable range for regularization parameters is determined. Also, the identified matrix parameters between 1 and 100 are examined in the constant regularization parameter, and the acceptable parameters are determined. The error in validation by simulated experiment for carbon, oxygen, hydrogen, sulfur, moisture, and ash content of municipal solid waste is 1.47, 3.81, 0.91, 0.22, 7.32, and 1.57 percent, respectively. In the next step, the developed procedure is applied to the Aradkooh waste-to-energy power plant in Tehran, Iran. The operating data are gathered from the power plant, and the municipal solid waste composition is estimated. Results indicate the feasibility of the proposed method, and the municipal solid waste composition and mass flow rate can be predicted indirectly by the flue gas analysis and some other measurements without needing to sample the municipal solid waste. According to the results, the carbon, oxygen, hydrogen, sulfur, moisture, and ash content of municipal solid waste in the Aradkooh power plant is 21.13, 41.96, 5.70, 0.01, 25.06, and 5.63 percent, respectively. Further, the mass flow rate of municipal solid waste and air are 0.53 and 2.5 kg per second. Finally, the sensitivity of the estimated municipal solid waste composition to errors is evaluated by error analysis.

Fixing sulfur dioxide by feeding calcine oxide into the rotary volatilization kiln in zinc smelting plant.

Sulfur dioxide (SO2) is a toxic pollutant and its fixation is a high cost but imperative task for sulfide metallurgy industry. Although being a mature technology for on-line fixation of SO2 by limestone injection in coal-fired boilers, its application is rarely investigated in the sulfide metallurgy plant. Extending this technology to the metallurgy industry is highly plausible, but with the feasibility and practicability waiting to be uncovered. Herein, feeding CaO into the rotary volatilization kiln as SO2-fixation agent is demonstrated to be an efficient in-furnace desulfurization strategy for zinc smelting plant. The sulfur distribution within the entire smelting process is systematically analyzed, determining that the critical procedure for pressuring the desulfurization system is the rotary volatilization kiln. The thermodynamics analysis shows that addition of CaO is feasible for SO2 fixation by forming CaS or restraining the reductive decomposition of SO42-. The industrial tests, including the online monitoring of kiln flue gas and kiln slag analysis, validate the thermodynamics analysis, realizing a 24.6% reduction of SO2 in the flue gas by converting gaseous SO2 to solid CaS via feeding 20% CaO. The present study highlights an effective strategy for on-line fixing the SO2, being a potential way for relieving the desulfurization pressures in zinc sulfide metallurgy plant.

Energy Utilization and Saving Opportunities in Process Industries: Case Study of Textile Manufacturing Industry in Kenya

The industrial sector is seriously threatened by high energy costs brought on by inefficient energy use. Energy, together with labor and raw materials, make up the majority of production costs in the textile industry. As a result, the only real way for the textile industry to turn a profit and maintain its competitiveness is to reduce its energy costs through energy conservation measures and energy management strategies. The main objective of the study was to investigate energy utilization in textile manufacturing plant and identify energy saving and conservation measures that help reduce energy costs. In the current work, energy investigation was carried out to determine performance of high energy consuming utility systems and equipment such as compressed air systems, boilers, motors, lighting systems and steam distribution systems. Boiler flue gas analysis test, air compressor air leak test, heat loss analysis for steam distribution system, motor load assessment and load variation trends in air compressor were done. Energy utilization analysis showed that high electricity consumption occurs in spinning (48%), followed by weaving (26%) and wet processing (22%). Statistical analysis of energy consumption in spinning, weaving and wet processing showed linear relationship between production and energy consumption with correlation coefficients (R2) of 0.782, 0.708 and 0.637 respectively which reveals that there continues to be a large potential of energy efficiency across all the major textile manufacturing processes in the plant. The study found potential savings in electric energy to be approximately 367,784 kWh/year, wood fuel savings 1,219 tones/year and furnace oil savings to be 22,275 L/year. The results displayed 31.6% overall energy cost saving potential with an average simple payback period of 0.5 years on the investigated high energy consuming utility systems and equipment. In conclusion, significant energy savings in the sector might be attained by implementing free or inexpensive investments including sealing air and steam leaks, insulating bare pipes, and properly drying wood fuel.

An Artificial Intelligence Regression Model for Prediction of NOx Emission from Flame Image

In this study, NOx emission has been estimated by processing the flame image of visible wavelength and its experimental verification has been presented. The experimental study has been performed by using a domestic coal boiler with a capacity of 85000 Kcal / h. The real NOx value has been measured from a flue gas analyzer device. The flame image has been taken by CCD camera from the observation hole on the side of the burner. The data set which is related to instantaneous combustion performance and flame images was recorded simultaneously on the same computer with time stamps once a second. The color flame image has been transformed into a gray scale. Features have been extracted from the gray image of flame. The features are extracted by using the cumulative projection vectors of row and column matrices. ANN regression model has been used as the learning model. The relationship between flame image and NOx emission has been obtained with the accuracy of R = 0.9522. Highly accurate measurement results show that the proposed NOx prediction model can be used in combustion monitor and control systems.

Analysis and distribution of volatile gases from catalytic pyrolysis of Sulcis low-rank coal

Catalytic pyrolysis of Sulcis low-rank coal over naturally occurring olivine, and home-made 15 wt%Ni/γ-Al2O3 catalyst was conducted for the upgrading of coal pyrolysis volatile gases in the temperature range ambient-900 °C under atmospheric pressure. Raw coal and mixtures of coal-additive (90:10 wt%) were slowly heated in temperature programmed mode using a laboratory-scale quartz furnace coupled in parallel to Fourier transform infrared (FTIR) spectrometer and GC chromatograph for quantitative analysis of flue gas. Coal pyrolysis with and without additives was also conducted by TG/DTG/DSC analysis at different heating rate (β = 15, 20, 30 °Cmin−1). DSC results clearly indicated some extra exothermic events during catalytic coal pyrolysis. Quantitative gaseous products distribution with temperature showed yields significantly and selectively improved with additives. Generally, more CO and CO2 were emitted under catalytic coal pyrolysis. Meanwhile, nickel catalyst exerted a marked positive effect on H2 yield overall in the temperature range 400–500 °C. The light hydrocarbons such as methane, ethane, propane and n-hexane substantially remaining unchanged, whereas a remarkable increase of emitted ethene was originated from catalytic pyrolysis. A deeper SO2 evolution was observed over olivine, whereas the N-containing compounds (NH3, NOx) were also modified in catalytic pyrolysis. Formaldehyde was also monitored, which represents a fragment originating from polycyclic aromatic side chains. Reaction kinetic study by a model-free isoconversional method indicated a complex multiple-step mechanism of coal pyrolysis, exception made for conversion values between 5% and 50% where a single-step reaction path was operating. The calculated average Ea and the pre-exponential factor were markedly reduced by the presence of additives. Meanwhile the compensation effect was also existing.

Experimental research on the volatilization and condensation of ammonium bisulfate as SCR byproduct

Abstract In this paper, the research progress of ammonium bisulfate (ABS) volatilization in coal-fired power plants the SCR denitrification process was reviewed. Combination with self-made experiments, SEM, flue gas analyzer and TG-DTG curves of ABS and ion chromatography. The volatilization and condensation characteristics of ABS were investigated carefully. Results show that as the temperature increased by 50 oC, the ABS/AS volatilization rate increased by an order of magnitude. The decomposition process of ABS should have a two-step reaction. The reaction in the initial volatiliza-tion stage is ABS dehydration turned into (NH4)2S2O7. The reaction in the rapid volat-ilization stage is (NH4)2S2O7 decomposed into NH3, N2, SO2 and H2O. There is an inter-section in the reaction temperature range (especially 300 oC) between the two-step re-action. This research provides an experimental basis for temperature control of ABS to avoid air pre-heater fouling.

Experimental Study on the Catalytic Ignition Characteristics of a Dual-Mode Ionic Liquid Propellant in Model Thrusters

An experimental study was carried out on the ignition characteristics of the HAN/(Emim)(EtSO4) (hydroxylammonium nitrate and 1-ethyl-3-methyl-imidazolium ethyl sulfate) dual-mode ionic liquid monopropellant in chemical propulsion mode in model thrusters. Firstly, a model thruster with a detachable convergent nozzle was designed and fabricated. Secondly, catalytic ignition experiments at different flow rates were carried out in atmosphere and in high chamber pressure environment, respectively, using a model thruster, with and without the convergent nozzle. During the catalytic ignition process, measurement methods such as thermocouple, pressure sensor, and flue gas analyzer were employed to obtain the temperature at different depths of the catalytic bed, the pressure of the combustion chamber, and the concentration variations of gaseous products CO, CO2, CH4, SO2, NO, and NO2. Then the three characteristic stages of water evaporation, HAN decomposition, and (Emim)(EtSO4) combustion were analyzed at the initiation time, and the reaction characteristics in the process of the catalytic ignition were analyzed. In addition, the composition and concentration of the combustion products at equilibrium were theoretically calculated. The effects of temperature and pressure on the concentrations of five main gaseous products were studied. Finally, the exhaust gas of the three groups of catalytic ignition experiments under different pressure environments was separately collected and measured with gas chromatography (GC) when the experiments approached equilibrium, the result of which roughly agrees with the theoretical calculations. These results are of great significance for exploring the chemical propulsion of the dual-mode ionic liquid propellant and understanding its physical catalytic combustion mechanisms.

Emissions Factors of Air Pollutants from Rice Straw Burning-hood Experiments

Abstract: The burning of rice straw produces a significant amount of particulate matter (PM) and gaseous air pollutants on a regional and global scale. In this study, the hood experiments were conducted to investigate the emission of air pollutants from rice straw burning (RSB). Samples of PM were collected isokinetically following the U.S. EPA methods 1, 1A, and 5. Gaseous pollutants were directly measured using a flue gas analyzer (Testo 350 XL). Emission factors (EF) (g.kg-1) determined for PM, CO2, CO, and SO2 were 17 ± 3.8, 1399 ± 228, 68 ± 22, and 1.5 ± 0.4, respectively meanwhile NO and NO2 were not detected in the flue gas. It was observed that flaming is the main phase in the process of RSB. The total emission from rice straw burning of 13 provinces in the Mekong River Delta of Vietnam in 2020 was estimated using the EF obtained from the hood experiments. The result shows that Kien Giang, An Giang, and Dong Thap were the high emission group in the Mekong River Delta, contributing 19%, 17%, and 14% to total emissions. The results of this study provide a scientific basis for further studies to determine EF from rice straw open burning in the fields and find sustainable measures to control this activity.

Influence of multiple gaseous medium injection on low-carbon iron ore sintering performance: Characteristics of natural gas and steam coupling injection

Hydrogen-rich gas and steam are widely regarded to be of great potential to mitigate CO2 emissions in iron ore sintering, these gases can regulate heat distribution in the sintering machines by replacing fossil fuels. However, most sintering machines only use one of the gases as the injecting medium, the potential of this technology has not been developed. In this paper, a multiple gaseous medium injection method contained natural gas and steam was experimentally investigated to solving this problem. Sintering tests were arranged to study the appropriate scheme of coupling injection and its influence on the sintering process, and the flue gas analyzer was used to detect the composition of the sintering flue gas in real time. Better sintering indexes were achieved by injecting the above two gaseous medium when the coke breeze ratio is unchanged, the results show that when 0.8 vol% natural gas is injected into the 4–14min, 0.15 vol% steam is injected into the 10–14 min, and 0.25 vol% steam is injected into the 15–18 min of sintering, the sintering yield increases by 2.42%, and the tumbler index increases by 2.72%. Under the above parameters, the coke breeze ratio can be reduced by 12.99%, the average NOx emissions decreased by 19.5%, and the average CO emissions decreased by 36.96% in the coupling injection interval (4–18min). After calculating the amount of coke breeze and natural gas in the optimal coupling injection sintering, CO2 emissions decreased by 7.66%, about 17.15 kg/t-sinter. Moreover, the PFR model was used to simulate the associated gas phase reaction after coupling injection which shows H2O significantly reduced CO emissions and change the reduction pathway of NO. Generally, sintering fuel consumption and greenhouse gas emissions have also been reduced, providing theoretical support for the change of iron ore sintering energy structure.

Flue gas analysis for biomass and coal co-firing in fluidized bed: process simulation and validation

Coal-conversion technologies, although used ubiquitously, are often discredited due to high pollutant emissions, thereby emphasizing a dire need to optimize the combustion process. The co-firing of coal/biomass in a fluidized bed reactor has been an efficient way to optimize the pollutants emission. Herein, a new model has been designed in Aspen Plus® to simultaneously include detailed reaction kinetics, volatile compositions, tar combustion, and hydrodynamics of the reactor. Validation of the process model was done with variations in the fuel including high-sulfur Spanish lignite, high-ash Ekibastuz coal, wood pellets, and locally collected municipal solid waste (MSW) and the temperature ranging from 1073 to 1223 K. The composition of the exhaust gases, namely, CO/CO2/NO/SO2 were determined from the model to be within 2% of the experimental observations. Co-combustion of local MSW with Ekibastuz coal had flue gas composition ranging from 1000 to 5000 ppm of CO, 16.2%–17.2% of CO2, 200–550 ppm of NO, and 130–210 ppm of SO2. A sensitivity analysis on co-firing of local biomass and Ekibastuz coal demonstrated the optimal operating temperature for fluidized bed reactor at 1148 K with the recommended biomass-to-coal ratio is 1/4, leading to minimum emissions of CO, NO, and SO2.