SO2 Pickup by Limestone and Dolomite Particles in Flue Gas

1970 ◽  
Vol 92 (2) ◽  
pp. 113-121 ◽  
Author(s):  
R. W. Coutant ◽  
R. E. Barrett ◽  
E. H. Lougher
Keyword(s):  
Experimental Data ◽  
Thermal Decomposition ◽  
Flue Gas ◽  
Particle Temperature ◽  
Initial Reaction ◽  
Dispersed Phase ◽  
Reaction Products ◽  
Boiler Furnace ◽  
Reaction Data ◽  
So2 Concentration

An investigation was made of the reaction between SO2 and limestone and dolomite particles in flue gas. Reaction data were generated by exposing the particles to flue gas in a dispersed-phase reactor that simulates localized boiler-furnace conditions. Variables included in the study were residence time, temperature, particle size, SO2 concentration, and chemical state of the stone. A model is hypothesized for the SO2- particle reaction that is consistent with the experimental data. The hypothesis states that the initial reaction products are sulfites, and that as the particle temperature rises above about 1400 deg F, SO2 is lost by thermal decomposition of the sulfite. Concurrently the sulfite can oxidize and/or disproportionate to form sulfate.

Thin Film Infrared Laser Pyrolysis Studies of Thermal Decomposition Mechanisms in Nitramine Propellants

1992 ◽  
Vol 296 ◽  
Author(s):  
Tod R. Botcher ◽  
Charles A. Wight
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Thermal Decomposition ◽  
Heat Conduction ◽  
Reaction Mechanism ◽  
Laser Pulse ◽  
Vapor Deposition ◽  
Pyrolysis Product ◽  
Initial Reaction ◽  
Reaction Products

AbstractThin films of RDX (1,3,5-trinitro-1,3,5-triazine) have been prepared by vapor deposition onto a 77 K substrate window and pyrolyzed with a pulsed CO2 laser. Each sample is rapidly quenched after the laser pulse by heat conduction into the cold substrate, and the initial reaction products are trapped on the window for examination by transmission FTIR spectroscopy. We have detected N2O4, the dimer of nitrogen dioxide, as an initial condensed phase pyrolysis product, confirming that scission of one of the N-N bonds is the first step in the reaction mechanism. No evidence was found for formation of methylene nitramine via a proposed concerted depolymerization pathway.

2-Mercaptothiazole and Derivatives as Vulcanization Accelerators

1962 ◽  
Vol 35 (5) ◽  
pp. 1360-1429 ◽  
Author(s):  
C. D. Trivette ◽  
E. Morita ◽  
E. J. Young
Keyword(s):  
Experimental Data ◽  
Kinetic Studies ◽  
Thiol Group ◽  
Zinc Stearate ◽  
Side Reactions ◽  
Initial Reaction ◽  
Reaction Products ◽  
Technical Literature ◽  
Free Thiol Group ◽  
The Individual

Abstract In this paper the subject of rubber vulcanization accelerated by 2-mercapto-benzothiazole and its derivatives has been reviewed. The technical literature from 1945 through 1960 and patents from 1932 through 1960 have been covered. Topics include: methods of synthesis and manufacture of these accelerators; application and compounding data on their use in rubber processing; and studies of the modes of action and mechanisms for the chemical reactions involved during accelerated vulcanization. Much disagreement exists concerning the mechanism of accelerated vulcanization and the action of thiazole accelerators. However, most of the conflict lies not in the experimental data collected, but in the interpretation of the meaning of the data. It is well documented that MBT and activators (zinc stearate, or zinc oxide and stearic acid) undergo an initial reaction; that these reaction products then react with sulfur and/or rubber hydrocarbon to form intermediate compounds; and that these intermediates then react in some manner to form sulfur crosslinks. Not known, for the most part, are the precise reaction steps involved; the sequence in which these reactions occur; the individual mechanisms, whether ionic, free radical, or neither, by which these reactions proceed; and the side reactions involved, if any (except in natural rubber, in which the non-crosslink forming cyclization reaction is well documented) which might lead to erroneous conclusions from the experimental data, particularly from kinetic studies. These same conclusions apply in general to thiazole sulfenamide accelerated sulfur vulcanization, with the exception that, in contrast to MBT, which has a free thiol group available for immediate reaction, the sulfenamide must first decompose or react in some manner before acceleration occurs. Sulfur and divalent sulfur compounds readily undergo both radical and ionic reactions, depending only on co-reactants and reaction conditions. At present, the reactions of sulfur with hydrocarbons and accelerators are not sufficiently well understood to draw concrete conclusions about the mechanism of acceleration. Further progress on elucidation of the mechanism will come with a better knowledge of the chemistry and mechanisms of sulfur reactions.

The Kinetics of Inhibition of the Action of Thrombin by the Fibrinopeptides Formed during the Clotting of Fibrinogen

1966 ◽  
Vol 16 (01/02) ◽  
pp. 277-295 ◽  
Author(s):  
A Silver ◽  
M Murray
Keyword(s):  
Amino Acids ◽  
Competitive Inhibition ◽  
Amorphous Material ◽  
Peptide Bond ◽  
Initial Reaction ◽  
Reaction Products ◽  
Coagulation Mechanism ◽  
Kinetics Of ◽  
Kinetics Of Inhibition ◽  
Burk Plot

SummaryVarious investigators have separated the coagulation products formed when fibrinogen is clotted with thrombin and identified fibrinopeptides A and B. Two other peaks are observed in the chromatogram of the products of coagulation, but these have mostly been dismissed by other workers. They have been identified by us as amino acids, smaller peptides and amorphous material (37). We have re-chromatographed these peaks and identified several amino acids. In a closed system of fibrinogen and thrombin, the only reaction products should be fibrin and peptide A and peptide B. This reasoning has come about because thrombin has been reported to be specific for the glycyl-arginyl peptide bond. It is suggested that thrombin also breaks other peptide linkages and the Peptide A and Peptide B are attacked by thrombin to yield proteolytic products. Thrombin is therefore probably not specific for the glycyl-arginyl bond but will react on other linkages as well.If the aforementioned is correct then the fibrinopeptides A and B would cause an inhibition with the coagulation mechanism itself. We have shown that an inhibition does occur. We suggest that there is an autoinhibition to the clotting mechanism that might be a control mechanism in the human body.The experiment was designed for coagulation to occur under controlled conditions of temperature and time. Purified reactants were used. We assembled an apparatus to record visually the speed of the initial reaction, the rate of the reaction, and the density of the final clot formed after a specific time.The figures we derived made available to us data whereby we could calculate and plot the information to show the mechanism and suggest that such an inhibition does exist and also further suggest that it might be competitive.In order to prove true competitive inhibition it is necessary to fulfill the criteria of the Lineweaver-Burk plot. This has been done. We have also satisfied other criteria of Dixon (29) and Bergman (31) that suggest true competitive inhibition.

scholarly journals Kinetics study on non-isothermal thermochemical liquefaction of corncobs in ethanol-water solution: Effect of ethanol concentration

2018 ◽  
Vol 197 ◽  
pp. 09005
Author(s):  
Bregas Siswahjono Tatag Sembodo ◽  
Hary Sulistyo ◽  
Wahyudi Budi Sediawan ◽  
Mohammad Fahrurrozi
Keyword(s):  
Experimental Data ◽  
Kinetic Models ◽  
Ethanol Concentration ◽  
Water Solution ◽  
Reaction Products ◽  
Gaseous Products ◽  
Bio Oil ◽  
Volatile Products ◽  
Calculation Results ◽  
Oil Gas

Corncobs are potentially processed into bio-oil through thermochemical liquefaction processes. It is difficult to construct kinetics models based on the compounds involved in the reaction. It would be made four kinetic models based on four reaction products, i.e., solids, bio-oil, gas and volatile products. The purposes of the study were to seek kinetics model of thermochemical liquefaction of corncobs in ethanol-water solution and to study the effect of ethanol concentration. The experiment of liquefaction processes of corncobs in ethanol-water solution using sodium carbonate catalyst was performed in the 150 ml autoclave equipped with a magnetic stirrer in the temperature up to 280°C. Four kinetic models were applied to predict the yield of four reaction product lumps. The calculation results were compared to the experimental data. Compared to the others, model 4 was the most realistic and closely matching to the experimental data. In model 4 the reaction mechanism was assumed that biomass (corncobs) first decomposed into bio-oil, followed by decomposition of bio-oil into volatile products reversibly and, finally, volatile products decomposed into gaseous products. The yield of bio-oil increased from 42.05% to 54.93% by increasing to ethanol concentration of 0% to 40%.

scholarly journals AN INNOVATE METHOD OF THERMOGRAVIMETRIC DATA ANALYSIS

2021 ◽  
Vol 64 (3) ◽  
pp. 24-32
Author(s):  
Mihail V. Mal’ko ◽  
Sergej V. Vasilevich ◽  
Andrey V. Mitrofanov ◽  
Vadim E. Mizonov
Keyword(s):  
Experimental Data ◽  
Thermal Decomposition ◽  
Thermogravimetric Analysis ◽  
Kinetic Parameters ◽  
Calculation Method ◽  
Kinetic Calculation ◽  
Pyrolysis Mechanism ◽  
Total Mass Loss ◽  
Thermogravimetric Data ◽  
Heavy Tar

The objective of the study is to examine the Coats-Redfern approximation and to propose an innovative kinetic calculation method for the complex process of the heavy tar thermal decomposition under non-isothermal process. The thermal decomposition process was examined using the thermogravimetric analysis. There are several kinetic models proposed to analyze pyrolysis mechanism in terms of the formal reaction. In this manner, the kinetic parameters of the pyrolysis process can be evaluated based on total mass loss (thermogravimetric analysis –TGA). The TGA procedures can be conducted with isothermal or non-isothermal conditions, but the experimental data obtained according to this procedure have to be transformed into appropriate correlation. The obtained results have shown that the reaction takes place within temperature range of 540 K to 700 K and the inductive period of the process is about 224 min. Kinetic parameters were estimated with using of the conventional Coats-Redfern method. A new kinetic calculation method has been designed to provide a less laboriousness of identifications procedures compared with Coats-Redfern approximation and to take into account an induction time of the process. As the outcome of this study, it was shown that the kinetic parameters estimated with using of the proposed model-fitted method gives the more appropriate correlation in comparison with the conventional Coats-Redfern method. The proposed method uses the Coats-Redfern algorithm for evaluation of the reaction mechanism, but the value of the constant rate is defined directly from experimental data on the conversion rate.

Research on Energy-Saving Control Technology of Boiler

2011 ◽  
Vol 383-390 ◽  
pp. 2603-2607
Author(s):  
Yao Yi ◽  
Guang Jian Chen ◽  
Jin Ling Jia
Keyword(s):  
Energy Saving ◽  
Intelligent Control ◽  
Flue Gas ◽  
Combustion Efficiency ◽  
Wind Pressure ◽  
Boiler Furnace ◽  
Door Opening ◽  
Boiler Efficiency ◽  
Secondary Air ◽  
Energy Saving Control

Focusing on energy-saving issues of boiler, this paper finds out the combustion conditions inside boiler furnace by monitoring and analysis on oxygen content of flue gas, carbon content of fly ash, CO and CO2 contents. The intelligent control of boiler combustion was achieved and combustion efficiency was rosen. Using neural network controlling model, automatic optimization of oxygen delivery volume,coal delivery volume, the total wind pressure of primary air, the secondary air-door opening degree and furnace negative pressure were achieved, and the boiler efficiency increasing by 5 ~ 7%.

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