scholarly journals Influence of Operating Conditions on the Thermal Behavior and Kinetics of Pine Wood Particles Using Thermogravimetric Analysis

Energies ◽  
2020 ◽  
Vol 13 (11) ◽  
pp. 2756 ◽  
Author(s):  
Lelis Gonzaga Fraga ◽  
João Silva ◽  
Senhorinha Teixeira ◽  
Delfim Soares ◽  
Manuel Ferreira ◽  
...  
Keyword(s):  
Thermogravimetric Analysis ◽  
Mass Loss ◽  
Heating Rate ◽  
Mass Loss Rate ◽  
Air Flow ◽  
Operating Conditions ◽  
Flow Rates ◽  
Pine Wood ◽  
The Third ◽  
Third Stage

Although there are many studies available in literature about biomass pyrolysis or devolatilization using thermogravimetric analysis (TGA), the effects of important operating parameters have infrequently been investigated for pine wood particle combustion. Consequently, the present study investigates the influence of particle size (63 µm to 1 mm), heating rate (5 to 243 °C/min), and air flow rate (10 to 150 mL/min) on the mass loss of pine wood using TGA. Additionally, the kinetic parameters considering the different conditions were determined to be incorporated in a numerical model. The effect of the heating rate on the thermal decomposition behavior has shown that the thermogravimetric and derivative thermogravimetric curves were shifted to higher temperatures with the increase in the heating rate. In this way, the heating rate affects the temperature at which the highest mass loss rate occurs as well as its value. Furthermore, comparing the higher and lower heating rate, the time to complete the combustion and the release are around 22 times higher when a higher heating rate is applied. On the other hand, the effects of four different air flow rates were compared and similar results were obtained. Regarding the kinetic analysis, it was verified at various heating and air flow rates with different particle sizes that the highest activation energy was mostly obtained during char combustion (~131–229 kJ/mol). Furthermore, in the second stage higher heating rates had the highest reactivity, and in the third stage there were not too many changes. In terms of the effect of air flow rates, a maximum variation of 15 kJ/mol was obtained in the third stage and, therefore, no significant effect on the reactivity for all particles was found.

Nitrogen Removal from Anaerobically-Treated Leachate

1984 ◽  
Vol 19 (1) ◽  
pp. 87-100
Author(s):  
D. Prasad ◽  
J.G. Henry ◽  
P. Elefsiniotis
Keyword(s):  
Nitrogen Removal ◽  
Air Flow ◽  
Operating Conditions ◽  
Air Flow Rate ◽  
Flow Rates ◽  
Anaerobic Filter ◽  
Ph Values ◽  
Wide Range ◽  
Ammonia Desorption ◽  
Effects Of Ph

Abstract Laboratory studies were conducted to demonstrate the effectiveness of diffused aeration for the removal of ammonia from the effluent of an anaerobic filter treating leachate. The effects of pH, temperature and air flow on the process were studied. The coefficient of desorption of ammonia, KD for the anaerobic filter effluent (TKN 75 mg/L with NH3-N 88%) was determined at pH values of 9, 10 and 11, temperatures of 10, 15, 20, 30 and 35°C, and air flow rates of 50, 120, and 190 cm3/sec/L. Results indicated that nitrogen removal from the effluent of anaerobic filters by ammonia desorption was feasible. Removals exceeding 90% were obtained with 8 hours aeration at pH of 10, a temperature of 20°C, and an air flow rate of 190 cm3/sec/L. Ammonia desorption coefficients, KD, determined at other temperatures and air flow rates can be used to predict ammonia removals under a wide range of operating conditions.

An investigation of the flow characteristics of multistage multiphase pumps

2018 ◽  
Vol 28 (3) ◽  
pp. 763-784 ◽  
Author(s):  
Jinya Zhang ◽  
Yongjiang Li ◽  
K. Vafai ◽  
Yongxue Zhang
Keyword(s):  
Volume Flow Rate ◽  
Volume Flow ◽  
Operating Conditions ◽  
Content Type ◽  
Multiphase Pump ◽  
The Third ◽  
Flow Parameters ◽  
Third Stage ◽  
Three Stages ◽  
Simulation Results

Purpose Numerical simulations of a multistage multiphase pump at different operating conditions were performed to study the variational characteristics of flow parameters for each impeller. The simulation results were verified against the experimented results. Because of the compressibility of the gas, inlet volume flow rate qi and inlet flow angle ßi for each impeller decrease gradually from the first to the last stage. The volume flow rate at the entrance of the pump q, rotational speed n and inlet gas volume fraction (IGVF) affect the characteristics of qi and ßi. Design/methodology/approach The hydraulic design features of the impellers in the multistage multiphase pump are obtained based on the flow parameter characteristics of the pump. Using the hydraulic setup features, stage-by-stage design of the multistage multiphase pump for a nominal IGVF has been conducted. Findings The numerical simulation results show that hydraulic loss in impellers of the optimized pump is substantially reduced. Furthermore, the hydraulic efficiency of the optimized pump increases by 3.29 per cent, which verifies the validation of the method of stage-by-stage design. Practical implications Under various operating conditions, qi and ßi decrease gradually from the first to the fifth stage because of the compressibility of the gas. For this characteristic, the fluid behavior varies at each stage of the pump. As such, it is necessary to design impellers stage by stage in a multistage rotodynamic multiphase pump. Social implications These results will have substantial effect on various practical operations in the industry. For example, in the development of subsea oilfields, the conventional conveying equipment, which contains liquid-phase pumps, compressors and separators, is replaced by multiphase pumps. Multiphase pumps directly transport the mixture of oil, gas and water from subsea oilwells through a single pipeline, which can simplify equipment usage, decrease backpressure of the wellhead and save capital costs. Originality/value Characteristics of a multistage multiphase pump under different operating conditions were investigated along with features of the inlet flow parameters for every impeller at each compression stage. Our simulation results have established that the change in the inlet flow parameters of every impeller is mainly because of the compressibility of the gas. The operational parameters q, n and IGVF all affect the characteristics of qi and ßi. However, the IGVF has the most prominent effect. Lower values of IGVF have an insignificant effect on the gas compressibility. Higher values of IGVF have a significant effect on the gas compressibility. All these characteristics affect the hydraulic design of the impellers for a multistage multiphase pump. In addition, the machining precision should also be considered. Considering all these factors, when IGVF is lower than 10 per cent, all the impellers in the pump can be designed uniformly. When IGVF varies from 10 to 30 per cent, the first two stages should be designed separately, and the latter stages are uniform starting with the second stage. When IGVF varies from 30 to 50 per cent, the first three stages should be designed separately, and the latter stages are going to be similar to the third stage. An additional increase in IGVF results in degeneration of the differential pressure of the pump, which will reduce the compressibility of the gas. As such, it can be deduced that only the first three stages should be designed separately, and the latter stages will be similar to the third stage. In addition, for the pump working under a lower volume flow rate than 25 m3/h, the first three stages should be designed individually while keeping the geometrical structure of the subsequent stages the same as the third stage.

Combustion of Bio-Coke (Highly Densified Biomass Fuel) Block in High-Temperature Air Flow

2011 ◽  
Author(s):  
Hiroyuki Ito ◽  
Yuto Sakai ◽  
Tamio Ida ◽  
Yuji Nakamura ◽  
Osamu Fujita
Keyword(s):  
High Temperature ◽  
Temperature Distribution ◽  
Mass Loss ◽  
Air Temperature ◽  
Degradation Rate ◽  
Loss Rate ◽  
Ignition Delay Time ◽  
Mass Loss Rate ◽  
Air Flow ◽  
Air Flow Rate

Bio-coke (BIC, highly densified biomass briquette), a newly developed biomass fuel as an alternative to coal coke which utilized in blast furnace, is employed in this study. This fuel is manufactured in highly compressed and moderate temperature conditions and has advantages in its versatility of biomass resources, high volumetric calorific value and high mechanical strength. Japanese knotweed is chosen as a biomass resource and is shaped into cylinder (48 mm in diameter and 85 mm in length). One of the most important characteristics of BIC is its high apparent density (1300 kg/m3; twice or more than that of an ordinary wood pellet). In the present study, combustion characteristics of a single BIC fuel in high temperature air flow (473–873 K, 550–750 NL/min.) are investigated. Air is preheated and blown to the bottom surface of the BIC. Ignition and subsequent combustion behavior are observed with monitoring gas temperature near the BIC, surface and inside the BIC temperature, and time dependent mass loss of the BIC is measured. In the case with low air temperature, low heat flux from the fuel surface leads to the broad temperature distribution inside the BIC accompanied by the increase in ignition delay time and, then, once ignition takes place degradation rate becomes larger than the case with high temperature air. On the other hand, mass loss rate for the case of solid surface combustion in the high temperature air does not depend on the air temperature but does depend on the air flow rate, which is a result of reduced degradation rate relating to narrow temperature distribution in depth caused by short ignition delay time. Consequently, it is suggested that the history of preheating, i.e. the preheated condition which is determined by air temperature and air flow rate, is an essential factor to determine the ignition mode in the early stage of BIC combustion and the mass burning velocity in the period of main combustion with flame. It is found that the mass loss rate of BIC in the gas-phase combustion period increases with decrease in supplied air temperature in this study.

Does 3rd dredge-up reduce AGB mass-loss?

2018 ◽  
Vol 14 (S343) ◽  
pp. 529-530
Author(s):  
Stefan Uttenthaler ◽  
Iain McDonald ◽  
Klaus Bernhard ◽  
Sergio Cristallo ◽  
David Gobrecht
Keyword(s):  
Mass Loss ◽  
Loss Rate ◽  
Mass Loss Rate ◽  
Pulsation Period ◽  
Agb Stars ◽  
Mid Infrared ◽  
The Third ◽  
Previous Sample ◽  
Good Probe

AbstractWe follow up on a previous finding that Miras containing the third dredge-up (3DUP) indicator technetium (Tc) in their atmosphere form a different sequence of K – [22] colour as a function of pulsation period than Miras without Tc. A near-to-mid-infrared colour such as K – [22] is a good probe for the dust mass-loss rate (MLR) of these AGB stars. Contrary to what one might naïvely expect, Tc-poor Miras show redderK – [22] colours (i.e. higher dust MLRs) than Tc-rich Miras at a given period. In the follow-up work, the previous sample is extended and the analysis is expanded towards other colours and ISO dust spectra to check if the previous finding is due to a specific dust feature in the 22 μm band. We also investigate if the same two sequences can be revealed in the gas MLR. Different hypotheses to explain the observation of two sequences in the P vs. K – [22] diagram are discussed and tested, but so far none of them convincingly explains the observations.

Thermal Decomposition Characteristics of Calcium Based Organic Compounds under Carbon Dioxide Enriched Atmosphere through Thermogravimetric Analysis

2012 ◽  
Vol 516-517 ◽  
pp. 494-497
Author(s):  
Sheng Li Niu ◽  
Ying Jie Li ◽  
Kui Hua Han ◽  
Jian Li Zhao ◽  
Chun Mei Lu
Keyword(s):  
Thermal Decomposition ◽  
Thermogravimetric Analysis ◽  
Organic Compounds ◽  
Mass Loss Rate ◽  
The Third ◽  
Whole Process ◽  
N2 Atmosphere ◽  
O2 Concentration ◽  
Lower Temperature ◽  
Co2 Atmosphere

Thermal decomposition characteristics of two kinds of calcium based organic compounds-calcium propionate and the product of the modified calcium hydroxide by propionic acid-under O2/N2 atmosphere and O2/CO2 atmosphere are investigated through thermogravimetric analysis. Thermal events of CP and MCP are divided into three segments. The second and the third ones for the two compounds are similar. O2/CO2 atmosphere reduces mass loss rate peak of the second segment and postpone the third segment. O2 concentration of 10 % is inadequate for a fast and sufficient reaction. When O2 concentration is enriched to 20 %, the whole process is shifted towards lower temperature zone. Further heightening O2 concentration to 30 % or 40 %, the effect is not remarkable.

scholarly journals Torrefaction of Straw from Oats and Maize for Use as a Fuel and Additive to Organic Fertilizers—TGA Analysis, Kinetics as Products for Agricultural Purposes

Energies ◽  
2020 ◽  
Vol 13 (8) ◽  
pp. 2064 ◽  
Author(s):  
Szymon Szufa ◽  
Grzegorz Wielgosiński ◽  
Piotr Piersa ◽  
Justyna Czerwińska ◽  
Maria Dzikuć ◽  
...  
Keyword(s):  
Thermogravimetric Analysis ◽  
Mass Loss ◽  
Kinetic Analysis ◽  
Heating Rate ◽  
Residence Time ◽  
Process Parameters ◽  
Research Work ◽  
Reaction Model ◽  
Organic Fertilizers ◽  
Electrical Furnace

This publication presents research work which contains the optimum parameters of the agri-biomass: maize and oat straws torrefaction process. Parameters which are the most important for the torrefaction process and its products are temperature and residence time. Thermogravimetric analysis was performed as well as the torrefaction process using an electrical furnace on a laboratory scale at a temperature between 250–525 °C. These biomass torrefaction process parameters—residence time and temperature—were necessary to perform the design and construction of semi-pilot scale biomass torrefaction installations with a regimental dryer and a woody and agri-biomass regimental torrefaction reactor to perform a continuous torrefaction process using superheated steam. In the design installation the authors also focused on biochar, a bi-product of biofuel which will be used as an additive for natural bio-fertilizers. Kinetic analysis of torrefaction process using maize and oat straws was performed using NETZSCH Neo Kinetics software. It was found that kinetic analysis methods conducted with multiple heating rate experiments were much more efficient than the use of a single heating rate. The best representations of the experimental data for the straw from maize straw were found for the n-order reaction model. A thermogravimetric analysis, TG-MS analysis and VOC analysis combined with electrical furnace installation were performed on the maize and oat straw torrefaction process. The new approach in the work presented is different from that of current scientific achievements due to the fact that until now researchers have worked on performing processes on oat and maize straws by means of the torrefaction process for the production of a biochar as an additive for natural bio-fertilizers. None of them looked for economically reasonable mass loss ratios. In this work the authors made the assumption that a mass loss in the area of 45–50% is the most reasonable loss for the two mentioned agri-biomass processes. On this basis, a semi-pilot installation could be produced in a further BIOCARBON project step. The kinetic parameters which were calculated will be used to estimate the size of the apparatuses, the biomass dryer, and biomass torrefaction reactor.

Effects of Sand Ingestion Through an Axial Fan With Blade Staggering

2008 ◽  
Author(s):  
Adel Ghenaiet
Keyword(s):  
High Speed ◽  
Air Flow ◽  
Operating Conditions ◽  
Sand Particle ◽  
Computational Domain ◽  
Axial Fan ◽  
Complex Flow ◽  
Particle Trajectories ◽  
Flow Rates ◽  
The Impact

This paper presents the numerical results of sand particle trajectories and erosion patterns in a single stage axial fan used in industrial air ventilation, and the subsequent deterioration of the blade geometry. Attention is focused in particular on the effects of rotor blade staggering and the operating flow rates. By adopting the Lagrangian formulation to study the dynamics of particulate air-flow, the flow-field within the blade passage is solved separately. Particle trajectories computation is based on a stochastic tracking algorithm, which includes eddy-lifetime concept for turbulence, and accounts for the complex flow patterns near walls, random particle rebound factors, in addition to particle size, shape and fragmentation. The equations of motion are solved in a stepwise manner, whereas, particle tracking in different cells of the computational domain is based on the finite element method. The computation of the particle trajectories yields the impact locations along the blade surfaces, where the corresponding erosion patterns are calculated by using experimental correlations. The results of the numerical simulations carried out at low and high concentrations of MIL-E5007E sand particles, for different fan blade staggering and mass flow rates, revealed that the main impacted areas are found along the blade leading edge, over a strip of the blade suction side and a large area of the pressure side, in addition to the tip and casing, but with rare impacts on the hub. The rates of erosion in this axial fan are found to depend strongly on the air flow condition and the blade staggering. In all operating conditions of this axial fan, the rates of erosion are lower in comparison to high speed fans and compressors. Erosion analysis could be used in aerodynamic and mechanical design procedures to produce turbomachinery blading that would be less susceptible to erosion.

scholarly journals Heating Characteristics of Palm Oil Industry Solid Waste and Plastic Waste Mixture using a Microwave Oven

2020 ◽  
Vol 20 (2) ◽  
pp. 174
Author(s):  
Novi Caroko ◽  
Harwin Saptoadi ◽  
Tri Agung Rohmat
Keyword(s):  
Energy Consumption ◽  
Mass Loss ◽  
Solid Waste ◽  
Heating Rate ◽  
Palm Oil ◽  
Loss Rate ◽  
Mass Loss Rate ◽  
Heating Process ◽  
Empty Fruit Bunch ◽  
Fixed Carbon

A microwave thermogravimetric analyzer was used to measure the characteristics of a mixture of palm oil solid waste (fiber, shell, and empty fruit bunch) and polyethylene terephthalate (PET). In the study, the range of palm oil solid waste composition ratios to PET used was 100:0, 75:25, 50:50, 25:75, and 0:100 (by weight). The study included the influence of the quality of raw material on the heating process. The mixture of palm oil solid waste (fiber, shell, and empty fruit bunch) and PET proved to impact the heating rate, mass-loss rate, and energy consumption. Based on the observation, empty fruit bunch-PET mixture had the highest heating rate (average 1.5039oC/s) than shell (average 0.6058oC/s), and fiber (0.9119oC/s) and also had the highest mass-loss rate (average 0.0253 g/s). The highest biomass (shell, empty fruit bunch, and fiber) and PET composition ratio give the highest rate of heating rate (average 1.8264oC/s) and mass-loss rate (average 0.02875 g/s). In addition, the increasing ratio of fixed carbon and material density will impact the increasing heating rate and mass-loss rate and decrease energy consumption. Therefore, fixed carbon and material gaps significantly affect the heating rate.

scholarly journals Thermal Conversion of Pine Wood and Kinetic Analysis under Oxidative and Non-Oxidative Environments at Low Heating Rate

Proceedings ◽  
2020 ◽  
Vol 58 (1) ◽  
pp. 23
Author(s):  
Lelis Gonzaga Fraga ◽  
João Silva ◽  
Senhorinha Teixeira ◽  
Delfim Soares ◽  
Manuel Ferreira ◽  
...  
Keyword(s):  
Thermal Decomposition ◽  
Mass Loss ◽  
Kinetic Analysis ◽  
Mass Loss Rate ◽  
Thermal Conversion ◽  
Inert Atmosphere ◽  
Thermochemical Conversion ◽  
Pine Wood ◽  
Oxidative Atmosphere ◽  
Conversion Stage

Atmosphere is one of the most significant factors in the thermal decomposition of biomass. In domestic or industrial biomass boilers, ambient oxygen concentration varies through time, which means that the reaction will change from pyrolysis to combustion. In this way, to analyze and compare each thermochemical conversion process, a simple analytical method, the non-isothermal thermogravimetric analysis, is carried out under oxidative (air) and non-oxidative (argon) environments at 10 °C/min and as a function of different flow rates (2 to 150 mL/min). Additionally, this work was complemented by a kinetic analysis considering a first-order reaction to each conversion stage and using the Coats–Redfern method. The effect of the atmosphere on the thermal decomposition behavior was evident. It was observed that the thermal decomposition of pine wood particles varied from three to two stages when the oxidative or inert atmosphere was applied. The presence of oxygen changes the mass loss curve mainly at high temperature, around 350 °C, where char reacts with oxygen. The maximum mass loss rate from experiments with the oxidative atmosphere is 15% higher than in an inert atmosphere, the average char combustion rate is approximately 5 times higher and the heat released reaches levels 3.44 times higher than in an inert atmosphere. Ignition and combustion indexes were also defined, and results revealed that particles are ignited faster under oxidative atmosphere and that, on average, the combustion index is 1.7 times higher, which reinforces the more vigorous way that the samples are burned and how char is burned out faster in the experiments with air. Regarding the kinetics analysis, higher activation energies, and consequently, lower reactivity was obtained under the oxidative atmosphere for the second stage (~125 kJ/mol) and under the inert atmosphere for the third thermal conversion stage (~190 kJ/mol).

scholarly journals EXPERIMENTAL STUDY ON INFLUENCE OF STACK EFFECT ON FIRE IN THE COMPARTMENT ADJACENT TO STAIRWELL OF HIGH RISE BUILDING

2014 ◽  
Vol 20 (1) ◽  
pp. 121-131 ◽  
Author(s):  
Wen Xi Shi ◽  
Jie Ji ◽  
Jin Hua Sun ◽  
S. M. Lo ◽  
Lin Jie Li ◽  
...  
Keyword(s):  
Experimental Study ◽  
Mass Loss ◽  
Heat Release ◽  
Release Rate ◽  
Tilt Angle ◽  
Loss Rate ◽  
Mass Loss Rate ◽  
Air Flow ◽  
Stack Effect ◽  
High Rise

In this paper, to study the influence of stack effect on fire in the compartment adjacent to a stairwell, a set of experiments were conducted by varying the pool size, top vent state and bottom vent size in a 1/3 scaled 12-layer-stairwell configuration. The phenomenon of methanol flame tilting in the fire room was observed and studied. Results showed that the flame tilt angle increases with an increase of Ri-1. The temperatures of hot gases in the fire room decrease due to the cooling effect of fresh air induced by stack effect. The mass loss rate of methanol fuel is influenced by fresh air flow sucked into fire room due to stack effect. On the basis of the experimental results, we conclude that the velocity of air flow into fire room is proportional to 1/3 power of the heat release rate in the stairwell.

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