On the Influence of Fluctuating Flow Rate Upon the Performance and Behaviour of Isothermal Reacting Systems

1998 ◽  
Vol 63 (6) ◽  
pp. 881-898
Author(s):  
Otakar Trnka ◽  
Miloslav Hartman

Three simple computational techniques are proposed and employed to demonstrate the effect of fluctuating flow rate of feed on the behaviour and performance of an isothermal, continuous stirred tank reactor (CSTR). A fluidized bed reactor (FBR), in which a non-catalytic gas-solid reaction occurs, is also considered. The influence of amplitude and frequency of gas flow rate fluctuations on reactant concentrations at the exit of the CSTR is shown in four different situations.

Author(s):  
B.S. Soroka ◽  
V.V. Horupa

Natural gas NG consumption in industry and energy of Ukraine, in recent years falls down as a result of the crisis in the country’s economy, to a certain extent due to the introduction of renewable energy sources along with alternative technologies, while in the utility sector the consumption of fuel gas flow rate enhancing because of an increase the number of consumers. The natural gas is mostly using by domestic purpose for heating of premises and for cooking. These items of the gas utilization in Ukraine are already exceeding the NG consumption in industry. Cooking is proceeding directly in the living quarters, those usually do not meet the requirements of the Ukrainian norms DBN for the ventilation procedures. NG use in household gas stoves is of great importance from the standpoint of controlling the emissions of harmful components of combustion products along with maintenance the satisfactory energy efficiency characteristics of NG using. The main environment pollutants when burning the natural gas in gas stoves are including the nitrogen oxides NOx (to a greater extent — highly toxic NO2 component), carbon oxide CO, formaldehyde CH2O as well as hydrocarbons (unburned UHC and polyaromatic PAH). An overview of environmental documents to control CO and NOx emissions in comparison with the proper norms by USA, EU, Russian Federation, Australia and China, has been completed. The modern designs of the burners for gas stoves are considered along with defining the main characteristics: heat power, the natural gas flow rate, diameter of gas orifice, diameter and spacing the firing openings and other parameters. The modern physical and chemical principles of gas combustion by means of atmospheric ejection burners of gas cookers have been analyzed from the standpoints of combustion process stabilization and of ensuring the stability of flares. Among the factors of the firing process destabilization within the framework of analysis above mentioned, the following forms of unstable combustion/flame unstabilities have been considered: flashback, blow out or flame lifting, and the appearance of flame yellow tips. Bibl. 37, Fig. 11, Tab. 7.


Author(s):  
Pengju Huo ◽  
Xiaohong Li ◽  
Yang Liu ◽  
Haiying Qi

AbstractThe influences of loose gas on gas-solid flows in a large-scale circulating fluidized bed (CFB) gasification reactor were investigated using full-loop numerical simulation. The two-fluid model was coupled with the QC-energy minimization in multi-scale theory (EMMS) gas-solid drag model to simulate the fluidization in the CFB reactor. Effects of the loose gas flow rate, Q, on the solid mass circulation rate and the cyclone separation efficiency were analyzed. The study found different effects depending on Q: First, the particles in the loop seal and the standpipe tended to become more densely packed with decreasing loose gas flow rate, leading to the reduction in the overall circulation rate. The minimum Q that can affect the solid mass circulation rate is about 2.5% of the fluidized gas flow rate. Second, the sealing gas capability of the particles is enhanced as the loose gas flow rate decreases, which reduces the gas leakage into the cyclones and improves their separation efficiency. The best loose gas flow rates are equal to 2.5% of the fluidized gas flow rate at the various supply positions. In addition, the cyclone separation efficiency is correlated with the gas leakage to predict the separation efficiency during industrial operation.


2012 ◽  
Vol 1380 ◽  
Author(s):  
S. Bello-Teodoro ◽  
R. Pérez-Garibay

ABSTRACTA method, based in leaching with SO2, to process low grade pyrolusite minerals has shown good results at laboratory scale. After the separation of the solid impurities, the dissolved manganese is subsequently precipitated using the SO2/O2 gas mixture as oxidising agent. In this research it was obtained a mathematical model to estimate the oxidative precipitation process, as a function of temperature, pH and SO2 gas flow rate. It was found that pH and temperature have the main influence in the reaction rate. An optimal SO2 concentration in the mixture must be used to avoid generation of reductive conditions. It was observed a most efficient reaction with a low gas flow rate injection. The predicted reaction rates presents a good concordance with the experimental results (R2=0.97), showing a worthy potential for practical uses.


1981 ◽  
Vol 14 (6) ◽  
pp. 462-466 ◽  
Author(s):  
HIROTSUGU HATTORI ◽  
KAZUYUKI TANAKA ◽  
KUNIHIKO TAKEDA

2013 ◽  
Vol 781-784 ◽  
pp. 1637-1645 ◽  
Author(s):  
Ting Jun Ma ◽  
Yi Qing Xu

The degradation effectiveness and reaction kinetics of representative organophosphorus (OP) pesticide in a packed-bed plasma reactor have been studied. Important parameters, including peak voltage, pulse frequency, gas-flow rate, initial concentration, diameter of catalyst particles, and thickness of catalyst bed which influences the removal efficiency, were investigated. Experimental results indicated that rogor removal efficiency as high as 80% can be achieved at 35 kV with the gas flow rate of 800 mL/min and initial concentration of 11.2 mg/m3.The removal efficiency increased with the increase of pulsed high voltage, and pulse frequency, the decrease of the diameter of catalyst particles and the thickness of catalyst bed. Finally, a model was established to predict the degradation of the rogor, which generally can simulate the experimental measurements to some degree.


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