Thermostatic Reactor Research Articles

Evaluation of Ca-Based Sorbents for Gaseous HCl Emissions Adsorption

The problem of acid gas exhaust emissions treatment has not been fully resolved at present. Dry adsorption of acid gases with alkaline sorbents is currently being investigated, to improve solid sorbents. In this study, 5 types of hydrated lime were characterised and tested. The sorption capacities were measured by means of a system consisting of a feed line (HCl/N2), a thermostatic reactor and a water absorber. The physical characteristics of sorbent samples were also compared. Analyses conducted with scanning electronic microscopy revealed that sample C1 showed uniform particle distribution. Samples C2 and C3 showed the co-presence of fine and coarse particles. Sample C4 showed very fine particles with agglomeration phenomena. In sample C5, fibrous elements were found. Energy dispersive spectrometry (EDS) analyses showed a similar composition of the samples, with the exception of the presence of Mg in some of them. After 30 min of testing, the following differences in sorption capacities with respect to C1 (3.59 mg g−1) were found: C2, −20%; C3, −13%; C4, −17%; C5, −3%. Higher sorption capacities were associated with more uniform particle size distributions. Conversely, agglomeration of fine particles may have adversely affected the performance of sorbents.

Effects of Tween 80 on clathrate and semiclathrate CO2 hydrate formation kinetics for carbon capture from CO2-rich gas mixtures

In this study, Tween 80 was chosen as a kinetic promoter to study the effect of non-ionic surfactant on CO2 hydrate formation kinetics. The experiments were carried out in a thermostatic reactor using CO2-rich gas mixtures with Tween 80 (0–3000 ppm) in both clathrate hydrates and tetra-n-butyl ammonium bromide (TBAB) semiclathrate hydrates. Analysis of variance (ANOVA) was used to analyze the difference among experimental results, and a decision box was proposed to evaluate the performance of systems studied. The apparent improvement in the induction time, gas uptake yield, and gas separation performance were observed in 1000-ppm or 2000-ppm Tween 80 in semiclathrate hydrates. Increased pressure further improved the kinetic promotion effect of Tween 80. However, a higher concentration of 3000-ppm Tween 80 was found to result in an inhibition effect on CO2 uptake yield in semiclathrate hydrates, although the induction time remained short. Compared with common anionic and cationic surfactants, 2000-ppm Tween 80 showed the best CO2 separation performance from gas mixtures in semiclathrate hydrates. No inhibition effect was observed in clathrate hydrates with studied concentrations of Tween 80.

The effects of electrical heating and additives on the microbial remediation of petroleum-contaminated soils

Although petroleum is an important source of energy and an economic driver of growth, it is also a major soil pollutant that has destroyed large swathes of vegetation and forest cover. Therefore, it is vital to develop affordable and efficient methods for the bioremediation of petroleum-contaminated forest soils to restore vegetation and improve tree survival rates. In this study, bioremediation experiments were performed in an electrically heated thermostatic reactor to test the effects of organic matter additives, surfactants, and oxygen providers of nine hydrocarbon-degrading fungal strains on crude oil removal rates. In the three soil temperatures tested (20 °C, 25 °C, and 30 °C), the highest average crude oil removal rate was at 25 °C (74.8%) and the lowest at 30 °C (49.4%). At each temperature, variations in the addition of organic matter and oxygen providers had significant effects on crude oil removal rate. Variations in surfactant addition was significant at 20 °C and 25 °C but insignificant at 30 °C. Given the same surfactant treatment, variations in temperature, organic additives, and oxygen providers was significant for crude oil removal rate. Treatments without surfactants and treatments with Tween80 exhibited their highest crude oil removal rates at 25 °C. However, treatments that included the SDS surfactant exhibited their highest crude oil removal rates at 30 °C. Amongst the treatments without surfactants, treatments with corn cob addition had the highest crude oil removal rates, and with surfactants, treatments that included the organic fertilizer exhibited the highest crude oil removal rates. Given the same organic fertilizer treatment, the highest crude oil removal rate was at 25 °C. At each level of oxygen availability, the maximum crude oil removal rate always occurred at 25 °C, and the treatments that included organic fertilizer exhibited the highest crude oil removal rates. Amongst the treatments without oxygen providers, treatments without surfactants had the highest crude oil removal rates, and with an oxygen provider, treatments with SDS addition exhibited the highest crude oil removal rates. Based on the crude oil removal rates of the treatments, we determined that S1W1O1 (addition of Tween80, organic fertilizers, and H2O2) was optimum for remediating petroleum-contaminated forest soils in cold, high-altitude regions. This study is helpful to vegetation restoration and reforestation on petroleum contaminated forestlands.

Experimental investigation on spontaneous combustion of coal affected by exothermic reaction of polyurethane in underground coal mines

Organic elastomers such as polyurethane are widely used as a filling material in underground coal mines. However, the risk of fire hazard in coal seams is increased due to the flammability of polyurethane. Laboratory tests illustrate that in a thermostatic reactor with initial temperature of 25 °C, the temperature during the production of polyurethane increases up to > 140 °C. Adiabatic oxidation experiments and TG–DTG analysis showed that the heating rate of the mixed samples of polyurethane and coal was higher than that of any single component in the initial oxidation stage. From the initial temperature to 100 °C, increasing the proportion of polyurethane was conducive to the acceleration of temperature rise. From 0.180 to 0.850 mm, the self-heating rate was inversely proportional to the particle size. At the initial stage, the low ventilation rate promoted the spontaneous combustion of mixed samples, but when the temperature is > 70 °C, an opposite trend was seen. Kinetic parameters suggested that the activation energy decreases with the introduction of polyurethane. According to the mathematical model, the variation of the spontaneous combustion period of coal and polyurethane was predicted.

Optimisation of process parameters using D-optimal for enzymatic synthesis of polycaprolactone

This work emphasizes on reactor scale synthesis of polycaprolactone using e-caprolactone as monomer and Candida antarctica lipase B enzyme as catalyst. The bio-polymerization was performed in 2 L thermostatic reactor by the conventional method with constant stirring. Optimisation of process parameters such as reactor temperature, reaction time, and mixing speed was carried out using response surface methodology based on D-optimal design. Molecular weight of the bio-polymer was chosen as the response for optimization, which is later characterised by gel permeation chromatography. The results show good agreement between predicted values and actual values obtained through the experiments.

A Microwave Thermostatic Reactor for Processing Liquid Materials Based on a Heat-Exchanger.

Microwaves have been widely used in the treatment of different materials. However, the existing adjustable power thermostatic reactors cannot be used to analyze materials characteristics under microwave effects. In this paper, a microwave thermostatic chemical reactor for processing liquid materials is proposed, by controlling the velocity of coolant based on PLC (programmable logic controller) in different liquid under different constant electric field intensity. A nonpolar coolant (Polydimethylsiloxane), which is completely microwave transparent, is employed to cool the liquid materials. Experiments are performed to measure the liquid temperature using optical fibers, the results show that the precision of temperature control is at the range of ±0.5 °C. Compared with the adjustable power thermostatic control system, the effect of electric field changes on material properties are avoided and it also can be used to detect the properties of liquid materials and special microwave effects.

Experimental studies of CO2 absorption enhancement in water-based nanofluids of carbon nanotubes

Abstract The improvement of CO2 absorption by CNT nanofluids with deionized water as the base fluid was studied experimentally. The reactor used was a stirred thermostatic reactor, operated batchwise. Pure CO2 was employed in all the experiments. The content of CNTs in the nanofluids ranged from 0 to 0.2% (wt). The acidification treatment of CNTs was employed to improve the stability of the nanofluids. The parameters, such as the concentration of CNT nanoparticles in the nanofluids, the stirring speed, the ultrasonic time for CNT nanofluid preparation, the nitration time and the amount of nitric acid for CNT acidification were varied. The results show that, with the increase of CNT concentration, the enhancement factor first increased and then leveled off after a certain value of the CNT concentration. With increasing stirring speed, the enhancement factor in stable functional CNT nanofluids declines monotonously, while in poorly dispersed raw CNT suspensions, it first increased and then reduced. The ultrasonic and nitration times and the amount of nitric acid have optimum values for the CO2 absorption enhancement. The mechanism of the CNT nanofluid enhancement of CO2 absorption is discussed accordingly. The absorption enhancement by the CNT nanofluid should be mainly attributable to convective motion induced by the Brownian motion and the shuttle effect.

Improvement of CO2 absorption using AL2O3 nanofluids in a stirred thermostatic reactor

The improvement of CO2 absorption by Al2O3 nanofluids with deionized water as the base fluid was studied experimentally. The reactor used was a stirred thermostatic reactor, operated batchwise. Pure CO2 was employed in all the experiments. The content of Al2O3 in nanofluids ranged from 0 to 0.2 % (wt). Sodium dodecyl benzene sulfonate (SDBS) was employed to improve the stability of the nanofluids, and the combined effect of nanoparticles and surfactants on the absorption enhancement was studied. The parameters such as the concentration of Al2O3 nanoparticles and surfactants, the stirring speed, and the ultrasonic time were varied. The results show that the nanoparticle mass fraction and the ultrasonic time have an optimum value for the CO2 absorption enhancement. The combination of surfactants and nanoparticles improves the enhancement performance of Al2O3 nanofluids more effectively than that without surfactants. With the increase of the stirring speed, the effective absorption ratio in stable nanofluids declines, while in poorly dispersed Al2O3 suspensions, it is increased first and then reduced. The mechanism of the Al2O3 nanofluid enhancing CO2 absorption is discussed accordingly. The absorption enhancement by the Al2O3 nanofluid is mainly attributable to convective motion induced by the Brownian motion.

Theoretical and Experimental Research of CO<sub>2</sub> Absorption Enhancement by Carbon Nano-Tube

The enhancement characteristics of carbon nanotubes (CNTs) on CO2 absorption were investigated experimentally a stirred thermostatic reactor. A comparison of CNTs with micro active carbon was made. From the experimental results, significant enhancement of CO2 absorption was obtained by both CNTs and micro active carbon, however, different change trends with stirring speed for the two solid particles was observed. With increasing stirring speed, the enhancement factor was decreased in AcC suspensions, whereas in CNT slurries it is increased. The experimental phenomena demonstrated a difference in enhancement mechanism for different size particles. For nanoparticles, besides the grazing effect, the micro-convection caused by Brownian motion should be also taken into account. The micro-convection strengthens the interaction of the concentration field around the particles and thus increases the diffusion rate of the solute. In addition, the agglomeration of the nanoparticle was also an important influencing factor. Due to the agglomeration of the particle, the enhancement factor for CNTs increases initially with increasing stirring speed. A three-dimensional microcosmic mass transfer model was developed to explain the experimental phenomena. Based on the model, the interaction of the flow field around the particles was analyzed.

Experimental and Theoretical Studies of CO2 Absorption Enhancement by Nano-Al2O3 and Carbon Nanotube Particles

The influence of nano-particles on CO2 absorption was studied experimentally in a stirred thermostatic reactor. Nano-Al2O3 and carbon nanotube (CNT) particles which showed different hydrophobic properties were chosen for the investigation. The experimental results were compared with that of micron-size activated carbon (AC) and Al2O3 particles. From the results, no enhancement by micron-size Al2O3 was found, and with the increase of Al2O3 concentration, the enhancement factor decreased. However, nano-Al2O3 showed a weak enhancement for the CO2 absorption. AC and CNT particles all intensified the gas-liquid mass transfer effectively, yet the trend of the enhancement factor with stirring speed for the two particles was different. With increasing stirring speed, the enhancement factor of AC particles was decreased, whereas in CNT suspensions it was increased. The experimental phenomena demonstrated a difference in enhancement mechanism for different size particles. For nano-particles, besides the influence of adsorbability and hydrophobicity, the micro-convection caused by Brownian motion should be also taken into account. Considering the micro-convection effect, a theoretical model was developed to shed light on the absorption enhancement by nano-particles.

An Unsteady Heterogeneous Mass Transfer Model for Gas Absorption Enhanced by Dispersed Third Phase Droplets

A model for one-dimensional unsteady heterogeneous mass transfer was developed based on Danckwerts' surface renewal theory in order to describe the mass transfer enhancement of absorption process for a slightly soluble gas in a gas-liquid-liquid system. The model accounts for the mass transfer resistance within the dispersed phase and the effect of emulsion viscosity on mass transfer. An analytical solution for enhancement factor was obtained by Laplace domain transformation. The absorption rates of carbon dioxide in the dodecane-in-water and castor oil-in-water systems were measured in a thermostatic reactor, and the enhancement factors were calculated at different volume fractions of dispersed phase and stirrer speeds. The model predictions agree well with the experimental data.

Effect of fine solid particles on absorption rate of gaseous CO2

The influence of the properties of solid particles in slurry on the absorption of CO2 in the slurry was investigated in a stirred thermostatic reactor. The absorption experiments were carried out in three different slurries consisting of water, cyclohexane and soybean oil, respectively, and three kinds of solid particles (active carbon, active alumina and silica gel) were incorporated into each of the above mentioned slurries separately. The experimental results show that the active carbon particles could enhance the absorption rate of gaseous CO2 in the aqueous slurry, while in the cyclohexane slurry, active carbon particles indicated no the absorption enhancement effect. However, it was observed that the active alumina and silica gel particles could enhance the absorption rate of CO2 in the cyclohexane slurry. These phenomena indicate that the solid particles, which could enhance the gaseous CO2 absorption rate, should possess two properties simultaneously, i.e. they rejected the solvent and had higher adsorption capacity for the solute. The experimental results also show that, as for those solid particles which could enhance the gas absorption rate, the enhancement increased quickly with the increase of solid concentration in slurry at first, and then reached a constant value gradually. It was also found that the enhancement factor was related to the coverage fraction of solid particles on the gas-liquid interface, and due to the reduction of surface fraction with increasing stirred speed, the enhancement factor decreased.

Oxidation inhibition of sulfite in dual alkali flue gas desulfurization system

A laboratory-scale well-mixed thermostatic reactor with continuously blasting air was used to investigate the oxidation inhibition of sulfite in dual alkali flue gas desulfurization (FGD) system. The effects of operating parameters such as pH value and catalyst concentration on the oxidation were studied. Sodium thiosulfate was used in the system, and was found that it significantly inhabited the sulfite oxidation. In the absence of catalyst, sodium thiosulfate at 12.67 mmol/L had an inhibition efficiency of approximately 98%. While in the presence of catalyst, sodium thiosulfate at 26.72 mmol/L had an inhibition efficiency less than 85.0%. The oxidation reaction order of sulfite in the sodium thiosulfate was determined to be -1.90 and -0.55 in the absence and presence of the catalyst, respectively. Apparent activation energy of oxidation inhibition was calculated to be 53.9 kJ/mol. Pilot tests showed that the consumption rate of thiosulfate agreed well with the laboratory-scale experimental results.

Photocatalytic Decolorization of Methylene Blue in Aqueous TiO2 Suspension

ABSTRACT A series of experiments were carried out to study the photocatalytic decolorization of methylene blue in a thermostatic reactor. The methylene blue solution for the experiment was syntheti...