Absorption Rate Of Carbon Dioxide Research Articles

Absorption of carbon dioxide into non-aqueous solutions ofN-methyldiethanolamine

The chemical absorption rate of carbon dioxide was measured in non-aqueous solvents, which dissolved N-methyldiethanoamine (MDEA), such as methanol, ethanol, n-propanol, n-butanol, ethylene glycol, propylene glycol, and propylene carbonate, and water at 298 K and 101.3 kPa using a semi-batch stirred tank with a plane gas-liquid interface. The overall reaction rate constant obtained from the measured rate of absorption of carbon dioxide under the condition of fast pseudo-first-order reaction regime was used to get the apparent reaction rate constant, which yields the second-order reaction rate constant and the reaction order of the overall reaction. There was approximately linear dependence of the logarithm of the rate constant for the overall second-order reaction on the solubility parameter of the solvent. In non-aqueous solutions of (MDEA), dissolved carbon dioxide is expected to react with solvated (MDEA) to produce an ion pair.

Reaction rate of carbon dioxide in glycidyl methacrylate solution using tricaprylylmethylammonium chloride as a catalyst

Carbon dioxide was absorbed into organic solutions of glycidyl methacrylate (GMA) in a semi-batch stirred tank with a plane gas-liquid interface at 101.3 kPa to measure absorption rates of carbon dioxide, from which the reaction kinetics between carbon dioxide and GMA were studied by using tricaprylylmethylammonium chloride catalyst. The reaction rate constants of the reaction were estimated by using the mass transfer mechanism accompanied by the pseudo-first-order reaction. An empirical correlation formula between the reaction rate constants and the solubility parameters of solvents such as toluene,N-methyl-2-pirrolidinone, and dimethyl sulfoxide was presented.

A RIGOROUS MODEL FOR ABSORPTION OF CARBON DIOXIDE INTO AQUEOUS N-METHYLDIETHANOLAMINE SOLUTION

ABSTRACT A rigorous model for absorption of carbon dioxide into aqueous N-methyldiethanolamine (MDEA) based on the assumption of reversible reactions and the simplified model with a pseudo-first order irreversible reaction hypothesis were employed to compare with experimental data. The experimental absorption rates were obtained from a characterized double stirred-cell absorber with a planar gas-liquid interface. It was demonstrated that the numerical solution of the rigorous model provides a better prediction for the absorption rate of carbon dioxide into aqueous MDEA solution than that of the simplified model. Only in the case of absorption experiments carried out at a low carbon dioxide partial pressure (p < 20 kpa) and low amine concentration (MDEAtotal < 1000 mol/m3), the assumption of pseudo-first order irreversible reaction is reasonable.

Reaction Kinetics of Carbon Dioxide with Diethanolamine in Polar Organic Solvents

The chemical absorption rate of carbon dioxide with diethanoamine was measured in such nonaqueous solvents as methanol, ethanol, n‐propanol, n‐butanol, ethylene glycol, propylene glycol, and propylene carbonate, and in water at 298 K and 101.3 kPa using a semibatch stirred tank with a plane gas‐liquid interface. The overall reaction rate constant obtained under the condition of fast reaction regime from the measured rate of absorption was used to get the elementary reaction rate constants in complicated reactions represented by reaction mechanism of carbamate formation and the order of overall reaction of CO2 with amine. Correlation between the elementary reaction rate constant and the solubility parameter of the solvent was presented.

Absorption Rate of Carbon Dioxide by K2CO3‐KHCO3 DEA Aqueous Solution

AbstractGas absorption rates of carbon dioxide from CO2‐air mixtures into K2CO3, K2CO3‐KHCO3, DEA and K2CO3‐KHCO3‐DEA solutions have been measured by using a wetted wall column. The method to determine the enhancement factor of chemical absorption is confirmed by the absorption of carbon dioxide in NaOH solution. The enhancement factor was correlated with the potassium concentration [K+] (= 2[K2CO3 + [KHCO3]), the DEA concentration, and the CO2‐loading ratio of the absorbent. The chemical reaction for CO2, absorption has been expressed by an (m,n)th order irreversible‐reaction model, where the reaction orders are m = 1 for CO2, n = 1.35 for DEA, n = 0.6 for K2CO3, and n = 0.6 and 1.35 for K2CO3 and DEA respectively. Experimental values of the enhancement factor were successfully reproduced by the calculations, where the reaction rate constants reflected the effect of loading ratio of the absorbent with carbon dioxide.

Solubility and absorption rate of carbon dioxide into non-respiring foods. Part 3: Cooked meat products

The solubility and diffusion of carbon dioxide into cooked meat products (cooked ham and meat sausage with different pH-levels) was determined at different starting pressures and gas to product volume ratios by monitoring pressure changes over time in a closed chamber at constant temperatures (0, 4, and 8 °C). Good correlation of the CO 2 solubility between the packaging parameters (gas to product volume ratio and initial partial pressure) and the meat products water content was found. The solubility of CO 2 followed Henry’s law and the initial partial pressure of CO 2 influenced the solubility mostly. Only small variations in the diffusion constants and absorption rates were found within the experimental design. A pH difference of 0.5 in the two meat sausage types did not influence either solubility or diffusion significantly.

Mixing and Crystallization Kinetics in Gas‐liquid Reactive Crystallization

AbstractA study of gas‐liquid reactive crystallization for CO2‐BaCl2‐H2O system was performed in a continuous flow crystallizer. The influences of mixing on the crystallization kinetics of barium carbonate crystals were investigated. The mixing parameters are stirrer speed, feed concentration, gas‐flow rate, pH of solution, addition rate of NaOH solution, and mean residence time. Under pH‐stat operation, the crystallization mechanism can be assessed by the addition rate of NaOH solution, which acts as an indicator for the absorption rate of carbon dioxide. Assuming a size‐independent agglomeration mechanism, the nucleation rate, growth rate and agglomeration kernel can be obtained, simultaneously, at steady state, by the method of moments. Evidence shows that feed concentration, feed rate, gas‐flow rate, and stirrer speed have a significant influence on the nucleation rates and mean particle sizes. This shows the effect of micromixing. The crystallization mechanism tends to be reaction limited when the feed concentration of barium chloride solution is higher than 5 mM, while at lower stirrer speeds and feed concentrations, the mechanism tends to be both mixing and reaction controlled. The growth rate depends on the mean supersaturation value and the pH of the solution and the mass‐transfer resistance cannot be completely eliminated in this work. For a monodispersal collision model, in the viscous sub‐range of turbulence, the agglomeration kernel can be expressed as β ∝ d3 $&amp;#x003F5; \bar$–1/4, showing a low efficiency of collision. The result is also demonstrated by the agglomeration kernel expression. Comparison with a liquid‐liquid‐mixing reactive crystallization system is also discussed.

Solubility and absorption rate of carbon dioxide into non-respiring foods. Part 2: Raw fish fillets

The solubility and diffusion of carbon dioxide into salmon, cod, anglerfish, wolf-fish and tuna fillets was determined by monitoring pressure changes over time in a closed chamber at constant temperatures. High correlation ( r 2>0.95) between the measured solubility against the theoretical solubility of water corrected for the total water and fat content of the fish was found. The average Henry’s constant for raw fish fillets at 0 °C was calculated to be 45.1 Pa ppm −1 (mg CO 2 per kg fish). Using the un-steady state solution of Fick’s law for the pressure history from 0 to 15 h gave better measurements of the CO 2 solubility in fishes than using the pressure drop over 20 h, mainly because the system does not reach equilibrium until about three days. In addition this graphical solution made determination of the diffusion coefficient possible. The average effective diffusion coefficient for CO 2 into raw fish fillets at chilled and superchilled temperatures was determined to be 1.69 × 10 −5 cm 2/s.

Solubility and absorption rate of carbon dioxide into non-respiring foods: Part 1: Development and validation of experimental apparatus using a manometric method

An apparatus to determine the solubility and rate of absorption of CO 2 from pressure changes over time was built and validated against water. A high correlation ( r 2>0.99) between the measured solubility and theoretical solubility was found. The solubility determinations using the manometric method were more accurate than using a CO 2 electrode. The solubility of CO 2 increased linearly with the partial pressure of CO 2, and a quadratic response was observed for the gas volume/product volume ( g/ p) ratio. The temperature dependency of the solubility is according to the temperature dependency of Henry’s constant. The rate of absorption is primarily affected by the %-level of CO 2 in the atmosphere, and the effective diffusion constant is primarily affected by the %-level of CO 2 and the g/ p-ratio. The time to reach 50% solubility was about 3 h and equilibrium was reached after 48 h.

CO2 Absorption Rate and Solubility in Monoethanolamine/Piperazine/Water

The solubility and absorption rate of carbon dioxide into monoethanolamine/piperazine/water were measured in a wetted wall column at 40–60°C. The total amine concentration was varied from 1.0 M to 5.0 M, with monoethanolamine blends containing 0 to 1.2 M piperazine. CO2 solubility and solution speciation were simulated by nine equilibrium reactions. Two of the equilibrium constants were adjusted to match literature data. The rate of absorption was predicted by the theory of diffusion with fast chemical reaction. Piperazine at 24 mol% of the total amine decreases CO2 equilibrium pressure by 50% and enhances the CO2 absorption rate by 50% to 100%. The CO2 enhancement factor decreases by a factor of 0.6 to 2 as loading decreases from 0 to 0.5 mol CO2/mole amine.

CO2 Absorption Rate and Solubility in Monoethanolamine/Piperazine/Water

The solubility and absorption rate of carbon dioxide into monoethanolamine/piperazine/water were measured in a wetted wall column at 40–60°C. The total amine concentration was varied from 1.0 M to 5.0 M, with monoethanolamine blends containing 0 to 1.2 M piperazine. CO2 solubility and solution speciation were simulated by nine equilibrium reactions. Two of the equilibrium constants were adjusted to match literature data. The rate of absorption was predicted by the theory of diffusion with fast chemical reaction. Piperazine at 24 mol% of the total amine decreases CO2 equilibrium pressure by 50% and enhances the CO2 absorption rate by 50% to 100%. The CO2 enhancement factor decreases by a factor of 0.6 to 2 as loading decreases from 0 to 0.5 mol CO2/mole amine.

Absorption Rate into a MDEA Aqueous Solution Blended with Piperazine under a High CO2 Partial Pressure

The absorption rate of carbon dioxide into a methyldiethanolamine (MDEA) aqueous solution blended with piperazine (PZ) under a high carbon dioxide partial pressure was studied by an experimental packed column. Also, the results indicated that the absorption rate of carbon dioxide at a high carbon dioxide partial pressure was larger than that of the calculation value from the kinetics model of atmospheric pressure because the Marangoni effect was strengthened by the elevated carbon dioxide partial pressure. The kinetics model modified by a carbon dioxide partial pressure was obtained as follows: NCO2 = fHCO2[DCO2(kMDEACMDEA + kPZCPZ)]1/2(P − P*), where f = 0.83[ln(P/100)]0.8 + 1.0 and 100 kPa ≤ P ≤ 625 kPa. The simulation of a commercial absorption column has verified this modified model successfully.

과도상태의 회전형 흡수기에서 혼합기체 중 이산화탄소 흡수량 계산 모델

A mathematical model for the prediction of carbon-dioxide absorption rate during the transient state of rotary type absorber is developed. The rotary type absorber operates using a fast rotating porous structure and clean water. The model for the transient state rotary type absorbers is based on the steady state model of packed tower absorber. The paper manipulates the operating data of an arbitrary quasi-steady state condition of rotary type absorber for the determination of the coefficients involved in the model developed. The prediction accuracy is evaluated from the measured data of rotary type absorber operated under fast transient state. The measured data include the mole fraction of carbon dioxide in mixed gas and the pressure of absorber. The relative error in carbon dioxide prediction is estimated to be 20% at maximum. The model is successfully applied for the prediction of the behavior of a closed cycle diesel engine.

Simulation of community metabolism and atmospheric carbon dioxide and oxygen concentrations in Biosphere 2

The complexity and scale of Biosphere 2 under materially closed conditions represented a unique opportunity to investigate couplings between elemental cycles and community metabolism. For this paper, simulation models were developed to explore individual biome effects on atmospheric composition and carbon cycling inside the enclosure. Results suggest soil respiration rates, light intensity, and acid–base equilibrium control atmospheric carbon dioxide and oxygen under materially closed conditions. Experiments with the overall Combined Biome model indicate: (1) the agriculture biome has a greater effect on atmospheric composition than the other biomes due to its large area, high net productivity, and biomass harvests; (2) the rainforest, which occupies ≈20% of Biosphere 2 area, may be responsible for 50% of total community production and respiration of oxygen; (3) the savannah and wetland biomes may be sources of carbon dioxide in the long term; (4) the ocean biome has less effect on atmospheric composition than the terrestrial biomes; and (5) the desert biome may lower carbon dioxide in the atmosphere as much as 2000 ppm during low light. Diurnal curve analyses of oxygen and carbon dioxide from early 1995 produced an average community gross production rate of 23 g O 2/m 2 per day, a community respiration rate of 25 g O 2/m 2 per day, and an average carbon dioxide absorption rate of 0.2 g CO 2/m 2 per h.

Diffusion Coefficients Significant in Modeling the Absorption Rate of Carbon Dioxide into Aqueous Blends of N-Methyldiethanolamine and Diethanolamine and of Hydrogen Sulfide into Aqueous N-Methyldiethanolamine

Absorption rates of gaseous CO2 into aqueous blends of N-methyldiethanolamine (MDEA) and diethanolamine (DEA) and of gaseous H2S into aqueous MDEA were measured in a quiescent, inverted-tube diffusiometer by monitoring the rate of pressure drop. A numerical model for absorption, diffusion, and reaction of CO2 and H2S in blends of MDEA, DEA, and water was developed. The model was used to regress diffusion coefficients of bicarbonate, carbamate, and MDEAH2CO3 for the case of CO2 absorption and of bisulfide ion for the case of H2S absorption from measured absorption rates. CO2 absorption rates and diffusion coefficients of bicarbonate, carbamate, and MDEAH2CO3 were obtained at 298.2 K and 318.2 K in aqueous solutions containing 50 mass % total amine at DEA:MDEA mole ratios of 1:20, 1:4, 1:3, and 2:3. H2S absorption rates and diffusion coefficients of bisulfide ion were obtained at 298.2 K and 318.2 K in aqueous solutions containing 20, 35, and 50 mass % MDEA.

Measurement of the Absorption Rate of Carbon Dioxide into Aqueous Diethanolamine

Absorption rates of gaseous CO2 into aqueous diethanolamine (DEA) solutions were measured in a quiescent, inverted-tube diffusiometer by monitoring the rate of pressure drop. The absorption rate was found to be insensitive to the diffusion coefficient of CO2 in solution but very sensitive to the diffusion rate of bicarbonate, protonated DEA, and carbamate ions. Evidence also suggested that chemical reaction equilibrium is rapid relative to diffusion. The diffusion coefficient of DEA in water was also measured using a Taylor dispersion apparatus. A numerical model was developed and used to regress diffusion coefficients of bicarbonate, carbamate, and protonated amine from measured absorption rates. CO2 absorption rates and diffusion coefficients of bicarbonate, carbamate, and protonated DEA were obtained at 298.2 K and 318.2 K in solutions containing 20, 35, and 50 mass % DEA in water.

High-pressure mass-transfer coefficients in the liquid phase of the binary systems carbon dioxide-methyl myristate and carbon dioxide-methyl palmitate

Mass-transfer coefficients in the liquid phase of the binary systems carbon dioxide-methyl myristate and carbon dioxidemethyl palmitate were determined at 40 and 50 °C and at pressures between 70 bar and the critical pressure of the mixture. The coefficients were measured by observing the absorption rate of carbon dioxide into a falling liquid film. Comparison of the experimental results with isothermal falling-film mass-transfer models shows that the measured coefficients are larger than those calculated, except near the critical point of the mixture. This is a result of the microconvection induced by a temperature change within the film surface, which, in turn, is caused by the release of heat during carbon dioxide absorption. Near the critical point of the mixture, the mass-transfer rates decline sharply.

垂直円管内気液二相上昇流における炭酸ガスの吸収

Carbon dioxide absorption rates into water were measured to determine volumetric mass transfer coefficients, kLa, in bubble and slug flow regimes of gas-liquid two-phase upflow through a 0.030m i.d. vertical tube. Axial local values of kLa decreased rapidly downstream from gas inlet. Axial averaged values of kLa, which is denoted by (kLa)z, were affected by gas velocity, uGO and distance from gas inlet, z, being correlated by the following equations:(kLa)z=0.81uGO1.20Z-0.62

A model for the absorption of sulphur dioxide into a limestone slurry

A model has been developed for the removal of sulphur dioxide from flue gas by absorption into a limestone slurry. The flue gas desulphurization unit consists of an absorber tower and an oxidation tank. Flue gas enters the absorption tower at the bottom and meets the limestone slurry. There are five important chemical reactions with a finite rate. The rate-limiting reactions are limestone dissolution, calcium sulphite precipitation and dissolution, gypsum precipitation, sulphur dioxide absorption and sulphite oxidation in the slurry. The model also accounts for the presence of chloride ions, magnesium ions and organic acids in the limestone slurry. The absorption rates of sulphur dioxide and carbon dioxide in the tower are calculated according to the two-film model. A non-uniform set of limestone particles is also included in the model. The model was tested against literature data and the agreement between the data and the model was satisfactory. A sensitivity analysis of the desulphurization process was carried out, the inputs to the model were changed and the results from the calculations were compared with the expected results. The response to the change in the inputs agreed well with the expected results.

Effective interfacial area in mechanical thin-layer apparatus

There were two main purposes in this investigation: measurement of the effective interfacial area (EIA) in mechanical thin-layer apparatus, and elaboration of a correlation between the EIA and the most important independent variables. The mechanical thin-layer apparatus was used as an absorber. The Danckwerts method was applied for the determination of the EIA during absorption. 214 measurements of the absorption rate of carbon dioxide in aqueous sodium hydroxide solutions were performed. All measurements were carried out under reduced pressure using pure carbon dioxide. A correlation was obtained between the EIA, the rate of irrigation per unit peripheral length, the circumferential velocity of the blades, the kinematic viscosity of the solution and the clearance between the inner surface of the tube and the edge of the blade. For all measurements the ratio of the EIA to the geometrical surface area F/ F g was within the range 1.02–1.70. The probable average error of the correlation is 5.1%.