Modeling Pressurized Dense Phase Coal Fluidization and Transport

2019 ◽  
Author(s):  
Bradley R. Adams ◽  
Taylor L. Schroedter
Keyword(s):  
Flow Rate ◽  
Particle Interaction ◽  
Drop Out ◽  
Coal Bed ◽  
Flow Ratio ◽  
Feed System ◽  
Horizontal Pipe ◽  
Flow Rates ◽  
Coal Particles ◽  
Coal Flow

Abstract A transient gas-solid model based on CPFD Software’s Barracuda Virtual Reactor was developed for a feed system to a pilot-scale pressurized oxy-coal (POC) reactor. A simplified geometry with a vertical coal hopper feeding into a 0.635-cm diameter horizontal pipe was used to represent key elements of the feed system. Coal particles were transported with 20-atm CO2 gas. The feed system was required to maintain a steady flow of gas and solids at a coal flow rate of approximately 3.8 g/s and a CO2 to coal mass ratio in the range 1–2. Sensitivity of model results to mesh size and particle interaction sub-model settings was assessed. Two design concepts were evaluated. A gravity-fed concept was found to be infeasible due to inadequate coal flow rates even at very high CO2 to coal flow ratios. This was due to gravitational forces being insufficient to move the pressurized coal from the hopper into the CO2 stream at the desired rate. A fluidized bed concept was found to provide the desired coal flow rate and CO2 to coal flow ratio. CO2 injected at the hopper base first fluidized the vertical coal bed before transporting it through a horizontal exit pipe. A second CO2 inlet downstream of the hopper exit pipe was used to dilute the fluidized coal and increase pipe velocities to minimize coal drop out. The amount of coal transported from the hopper was dependent on the net CO2 hopper flow but independent of the CO2 dilution flow. This meant that the coal flow rate and CO2 to coal flow ratio could be controlled independently. Pipe exit coal flow rates were found to fluctuate at levels acceptable for steady burner operation.

Development of a High Pressure Dry Coal Feed System for a 100 kWt Oxy-Coal Reactor

2020 ◽  
Vol 142 (7) ◽  
Author(s):  
Taylor Schroedter ◽  
Bradley R. Adams ◽  
Jacob Tuia ◽  
Andrew Fry
Keyword(s):  
Particle Diameter ◽  
Flow Ratio ◽  
Feed System ◽  
Horizontal Pipe ◽  
Bench Scale ◽  
Coal Particles ◽  
Simplifying Assumptions ◽  
Coal Flow ◽  
Co2 Flow ◽  
Burner Operation

Abstract A design concept to feed dry coal from a hopper to a 100 kWt pressurized oxy-coal (POC) reactor using CO2 at 2 MPa was developed using transient computational fluid dynamics (CFD) simulations and bench-scale measurements. The feed system was required to maintain a steady flow of gas and solids at a coal flowrate of approximately 3.8 g/s and a CO2-to-coal mass ratio in the range 1–2. A 5.08-cm diameter vertical coal hopper feeding into a 0.635-cm diameter horizontal pipe was used to represent key elements of the feed system. A fluidized bed concept was found capable of providing the desired coal flowrate and CO2-to-coal flow ratio. Use of separate fluidization and dilution flows allowed the coal flowrate and CO2-to-coal flow ratio to be controlled independently. The amount of coal transported from the hopper was dependent on the net CO2 flow in the hopper but independent of the CO2 dilution flow. Pipe exit coal flowrates were found to fluctuate at levels acceptable for steady burner operation. Tests from a bench-scale apparatus using Pittsburgh 8 coal with a median particle diameter of 50 µm and moisture content of 6% confirmed the feasibility of the fluidization design. However, for a given CO2 fluidization flowrate, experimental coal flowrates were lower than predicted coal flow, in part due to simplifying assumptions of dry, spherical coal particles and smooth piping in the simulations.

Effect of Feed-Flow Rate in a Solid-Liquid Hydrocyclone Based on Total Solid Recovery Equation

2017 ◽  
Vol 751 ◽  
pp. 173-179
Author(s):  
Pichai Soison ◽  
Pakpoom Supachart ◽  
Pratarn Wongsarivej
Keyword(s):  
Particle Size ◽  
Flow Rate ◽  
Concentration Ratio ◽  
Separation Efficiency ◽  
Total Solid ◽  
Feed Flow Rate ◽  
Solid Concentration ◽  
Flow Ratio ◽  
Flow Rates ◽  
Solid Liquid

Many studies of hydrocyclones have confirmed that increasing the feed-flow rate results in a higher separation efficiency. The purpose of this study was to investigate the separation efficiency for a 100 mm solid–liquid hydrocyclone with 1 and 2 wt% solid concentrations at feed-flow rates of 2, 3, 4, 5 and 6 m3/hr. The solid concentration and particle size distribution were analysed using drying–weighing and a particle-size analyser (Mastersizer 2000), respectively. The experimental results indicated that an increase in feed-flow rate from 2 to 4 m3/hr produced decreased separation efficiency. However, when the feed-flow rates increased from 4 to 6 m3/hr, the separation efficiency increased. Furthermore, the higher the feed-flow rate, the smaller the cut size. A novel separation efficiency equation in terms of the concentration ratio and flow ratio is also proposed.

Impact of recycled effluent on the hydrolysis during anaerobic digestion of vegetable and flower waste

2008 ◽  
Vol 58 (8) ◽  
pp. 1637-1643 ◽  
Author(s):  
F. Lü ◽  
P. J. He ◽  
L. P. Hao ◽  
L. M. Shao
Keyword(s):  
Lactic Acid ◽  
Flow Rate ◽  
Degradation Rate ◽  
Solid Phase ◽  
Flow Ratio ◽  
Acid Fermentation ◽  
Flow Rates ◽  
Operation Stability ◽  
Lower Ratio ◽  
Butyric Acid Fermentation

Two trials were established to investigate the effect of recycled effluent on hydrolysis during anaerobic co-digestion of vegetable and flower waste. Trial I evaluated the effect by regulating the flow rate of recycled effluent, while Trial II regulated the ratio of hydrolytic effluent to methanogenic effluent, which were recycled to hydrolysis reactor. Results showed that the recirculation of methanogenic effluent could enhance the buffer capability and operation stability of hydrolysis reactor. Higher recycled flow rate was favourable for microbial anabolism and further promoted hydrolysis. After 9 days of hydrolysis, the cumulative SCOD in the hydrolytic effluent reached 334, 407, 413, 581 mg/g at recycled flow rates of 0.1, 0.5, 1.0, 2.0 m3/(m3·d), respectively. It was feasible to recycling a mixture of hydrolytic and methanogenic effluent to the hydrolysis reactor. This research showed that partially introducing hydrolytic effluent into the recycled liquid could enhance hydrolysis, while excessive recirculation of hydrolytic effluent will inhibit the hydrolysis. The flow ratio 1:3 of hydrolytic to methanogenic effluent was found to provide the highest hydrolysis efficiency and degradation rate of lignocelluloses-type biomass, among four ratios of 0:1, 1:3, 1:1 and 3:1. Under this regime, after 9 days of hydrolysis, the cumulative TOC and TN in the hydrolytic effluent reached 162 mg/g and 15 mg/g, the removal efficiency of TS, VS, C and cellulose in the solid phase were 60.66%, 62.88%, 58.35% and 49.12%, respectively. The flow ratio affected fermentation pathways, i.e. lower ratio favoured propionic acid fermentation and the generation of lactic acid while higher ratio promoted butyric acid fermentation.

Adaptive Prediction of Transient Air Fuel Ratio Based on Forgetting Factor Algorithm for a Coal-Bed Gas Engine

2011 ◽  
Vol 130-134 ◽  
pp. 814-819
Author(s):  
Qin Teng ◽  
Xiang Gong ◽  
Peng An
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Gas Flow ◽  
Coal Bed ◽  
Forgetting Factor ◽  
Fuel Gas ◽  
Flow Rates ◽  
Gas Engine ◽  
Adaptive Models

In order to solve the problems of pumping fluctuations and bandwidth limitation to dynamic air fuel ratio (AFR) control for a coal-bed gas engine, adaptive models for air mass flow rate and fuel gas mass flow rate in intake system and exhaust AFR were constructed by a recursive identification method based on the forgetting factor (FF) algorithm. A linear time-varying equation error model was selected as the structure of the adaptive models. Firstly, the throttle position and crankshaft speed signals were used to predict the air and fuel gas flow rates. Secondly, the AFR was predicted in real time according to the estimated air and fuel gas flow rates. The trade-off between tracking ability and noise sensitivity was realized by adjusting a FF. The experiment validations at transient operating conditions of the engine accelerating and decelerating show that, adaptive recursive models of the air and gas flow rates with a larger FF can not only track the averaging values of the flow rates, but also deal with the phase delays introduced by the filter, the AFR adaptive recursive model with a smaller FF can predict transient AFR accurately.

scholarly journals Experimental Evaluation of Optimum Water to Air Flow Ratio in an Induced Draft Wet Cooling Tower

2019 ◽  
Vol 4 (2) ◽  
Author(s):  
Talib O Ahmadu ◽  
Hamisu A Dandajeh
Keyword(s):  
Water Flow ◽  
Flow Rate ◽  
Cooling Tower ◽  
Air Flow ◽  
Water Flow Rate ◽  
Cooling Power ◽  
Cooling Efficiency ◽  
Flow Ratio ◽  
Flow Rates ◽  
Optimum Water

Cooling towers are devices used to dissipate waste thermal heat to the ambient environment. Appropriate cooling water and air flow rates are necessary to ensure optimum cooling power and cooling efficiency. Also, a simple design is required for cost effectiveness and minimal maintenance issues. This paper experimentally evaluates the cooling power, cooling efficiency, as well as the optimum water to air flow ratio in a spray type induced draft wet cooling tower. The cooling tower, 6 kW cooling capacity, was developed to operate without packings. The experiments were conducted for three different air flow rates and six different water flow rates. Four different inlet water temperatures of 35, 40, 45 and 50 oC were used. The temperature range is a typical range for inlet water temperature to the cooling tower for an absorption cooling system. For each of the inlet water temperatures, air and water flow rates were varied. The effects of this variation on cooling power and cooling efficiency were studied. Effect of varying water to air flow ratio on cooling power and cooling efficiency were studied. Results showed that the cooling power increased with increasing water flow rate, while the cooling efficiency decreased with increasing water flow rate. Decreasing the air flow rate was seen to cause a decrease in both cooling power and cooling efficiency. Maximum cooling power and cooling efficiency of 5.33 kW and 63% respectively were obtained. An optimum water to air flow ratio of 1.6 was obtained. The cooling tower was seen to have operated satisfactorily without packings. Keywords— cooling tower, cooling power, cooling efficiency, flow ratio, thermal energy

EFFECT OF COAL FLOW RATE AND BURNER LOCATION IN A PUSHER TYPE REHEATING FURNACE

2018 ◽  
Author(s):  
Saurav Chakraborty ◽  
Sajal Randhar ◽  
Abhimanyu Baruah ◽  
Prabal Talukdar
Keyword(s):  
Flow Rate ◽  
Reheating Furnace ◽  
Coal Flow

Hydraulic model of a water cooling system in a chemical plant

1988 ◽  
Vol 53 (4) ◽  
pp. 788-806
Author(s):  
Miloslav Hošťálek ◽  
Jiří Výborný ◽  
František Madron
Keyword(s):  
Flow Rate ◽  
Cooling System ◽  
Cooling Water ◽  
Graph Algorithm ◽  
Automatic Generation ◽  
Hydraulic Calculation ◽  
Return Flow ◽  
Flow Rates ◽  
Pressure Losses ◽  
Controlled Flow

Steady state hydraulic calculation has been described of an extensive pipeline network based on a new graph algorithm for setting up and decomposition of balance equations of the model. The parameters of the model are characteristics of individual sections of the network (pumps, pipes, and heat exchangers with armatures). In case of sections with controlled flow rate (variable characteristic), or sections with measured flow rate, the flow rates are direct inputs. The interactions of the network with the surroundings are accounted for by appropriate sources and sinks of individual nodes. The result of the calculation is the knowledge of all flow rates and pressure losses in the network. Automatic generation of the model equations utilizes an efficient (vector) fixing of the network topology and predominantly logical, not numerical operations based on the graph theory. The calculation proper utilizes a modification of the model by the method of linearization of characteristics, while the properties of the modified set of equations permit further decrease of the requirements on the computer. The described approach is suitable for the solution of practical problems even on lower category personal computers. The calculations are illustrated on an example of a simple network with uncontrolled and controlled flow rates of cooling water while one of the sections of the network is also a gravitational return flow of the cooling water.

scholarly journals Geometrical Optimization of a Venturi-Type Microbubble Generator Using CFD Simulation and Experimental Measurements

Designs ◽  
2021 ◽  
Vol 5 (1) ◽  
pp. 4
Author(s):  
Dillon Alexander Wilson ◽  
Kul Pun ◽  
Poo Balan Ganesan ◽  
Faik Hamad
Keyword(s):  
Water Flow ◽  
Flow Rate ◽  
Cfd Simulation ◽  
Air Flow ◽  
Bubble Diameter ◽  
Diameter Ratio ◽  
Experimental Measurements ◽  
Cfd Model ◽  
Flow Rates ◽  
Throat Diameter

Microbubble generators are of considerable importance to a range of scientific fields from use in aquaculture and engineering to medical applications. This is due to the fact the amount of sea life in the water is proportional to the amount of oxygen in it. In this paper, experimental measurements and computational Fluid Dynamics (CFD) simulation are performed for three water flow rates and three with three different air flow rates. The experimental data presented in the paper are used to validate the CFD model. Then, the CFD model is used to study the effect of diverging angle and throat length/throat diameter ratio on the size of the microbubble produced by the Venturi-type microbubble generator. The experimental results showed that increasing water flow rate and reducing the air flow rate produces smaller microbubbles. The prediction from the CFD results indicated that throat length/throat diameter ratio and diffuser divergent angle have a small effect on bubble diameter distribution and average bubble diameter for the range of the throat water velocities used in this study.

scholarly journals Comparison of different models to calculate the viscosity of biogas and biomethane in order to accurately measure flow rates for conformity assessment

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Karine Arrhenius ◽  
Oliver Büker
Keyword(s):  
Binary Mixtures ◽  
Flow Rate ◽  
Correction Method ◽  
Gas Mixtures ◽  
Conformity Assessment ◽  
Flow Rates ◽  
Unknown Composition

AbstractThe study presents an optimised method to correct flow rates measured with a LFE flowmeter pre-set on methane while used for gas mixtures of unknown composition at the time of the measurement. The method requires the correction of the flow rate using a factor based on the viscosity of the gas mixtures once the composition is accurately known. The method has several different possible applications inclusive for the sampling of biogas and biomethane onto sorbent tubes for conformity assessment for the determination of siloxanes, terpenes and VOC in general. Five models for the calculation of the viscosity of the gas mixtures were compared and the models were used for ten binary mixtures and four multi-component mixtures. The results of the evaluation of the different models showed that the correction method using the viscosity of the mixtures calculated with the model of Reichenberg and Carr showed the smallest biases for binary mixtures. For multi-component mixtures, the best results were obtained when using the models of Lucas and Carr.

Assessment of the Use of Humidified Nasal Cannulas for Oxygen Therapy in Patients with Epistaxis

ORL ◽  
2021 ◽  
pp. 1-5
Author(s):  
Jingjing Liu ◽  
Tengfang Chen ◽  
Zhenggang Lv ◽  
Dezhong Wu
Keyword(s):  
Flow Rate ◽  
Oxygen Therapy ◽  
Preliminary Investigation ◽  
Nasal Cannula ◽  
Low Flow ◽  
Antiplatelet Drugs ◽  
Flow Rates ◽  
The Past ◽  
Oxygen Inhalation ◽  
Significant Difference

<b><i>Introduction:</i></b> In China, nasal cannula oxygen therapy is typically humidified. However, it is difficult to decide whether to suspend nasal cannula oxygen inhalation after the nosebleed has temporarily stopped. Therefore, we conducted a preliminary investigation on whether the use of humidified nasal cannulas in our hospital increases the incidence of epistaxis. <b><i>Methods:</i></b> We conducted a survey of 176,058 inpatients in our hospital and other city branches of our hospital over the past 3 years and obtained information concerning their use of humidified nasal cannulas for oxygen inhalation, nonhumidified nasal cannulas, anticoagulant and antiplatelet drugs, and oxygen inhalation flow rates. This information was compared with the data collected at consultation for epistaxis during these 3 years. <b><i>Results:</i></b> No significant difference was found between inpatients with humidified nasal cannulas and those without nasal cannula oxygen therapy in the incidence of consultations due to epistaxis (χ<sup>2</sup> = 1.007, <i>p</i> &#x3e; 0.05). The same trend was observed among hospitalized patients using anticoagulant and antiplatelet drugs (χ<sup>2</sup> = 2.082, <i>p</i> &#x3e; 0.05). Among the patients with an inhaled oxygen flow rate ≥5 L/min, the incidence of ear-nose-throat (ENT) consultations due to epistaxis was 0. No statistically significant difference was found between inpatients with a humidified oxygen inhalation flow rate &#x3c;5 L/min and those without nasal cannula oxygen therapy in the incidence of ENT consultations due to epistaxis (χ<sup>2</sup> = 0.838, <i>p</i> &#x3e; 0.05). A statistically significant difference was observed in the incidence of ENT consultations due to epistaxis between the low-flow nonhumidified nasal cannula and nonnasal cannula oxygen inhalation groups (χ<sup>2</sup> = 18.428, <i>p</i> &#x3c; 0.001). The same trend was observed between the 2 groups of low-flow humidified and low-flow nonhumidified nasal cannula oxygen inhalation (χ<sup>2</sup> = 26.194, <i>p</i> &#x3c; 0.001). <b><i>Discussion/Conclusion:</i></b> Neither high-flow humidified nasal cannula oxygen inhalation nor low-flow humidified nasal cannula oxygen inhalation will increase the incidence of recurrent or serious epistaxis complications; the same trend was observed for patients who use anticoagulant and antiplatelet drugs. Humidification during low-flow nasal cannula oxygen inhalation can prevent severe and repeated epistaxis to a certain extent.

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