Study on The Effect of Solid Properties on The Hydrodynamics in an Ebullated Bed Reactor

Published data on the hydrodynamics of ebullated- bed reactors (EBRs) used in the H-Oil process are scarce. In the present work, the effect of solid properties (e.g., particle size, and degree of hydrophobicity) on the hydrodynamics and foaminess in a lab-scale cold model of an (EBR) was investigated. 20wt. % MgSO4 solution was utilized as the liquid phase to imitate the hydrodynamic trends in the industrial-scale EBR of the hydro-conversion process. Experimental results depicted that the flow regime of the multiphase system can be readily evaluated by using the pressure drop technique. The turning from the bubbly to the turbulent system is enhanced with diminishing particle size, and decreasing particle hydrophobicity. Moreover, the degree of particle hydrophobicity was inversely proportional to the average gas holdup in the EBR. The reduction in average gas holdup was 7.9 % using hydrophobic particles more than that of the hydrophilic one. In the EBR, it was found that bubble sizes were increased with both gas velocity and the axial location far from the gas distributor while liquid velocity has negative impact on bubble size. The experimental work revealed that hydrophobic particles of smaller size (250 μrm) reduced foaming by 70% using 20 vol. % of solid loading and gas and liquid velocities of 10 and 0.15 cm s-1 respectively. This outcome revealed that the surface of catalyst particles used can be modified to act as foaminess- reducer in fluidized bed hydro conversion reactors.

How Long Do Black Carbon Particles Linger in the Atmosphere?

Researchers uncover how black carbon evolves from hydrophobic particles to cloud nucleation sites, eventually removing the heat-absorbing particles from the sky.

Super liquid repellent surfaces for anti-foaming and froth management

Wet and dry foams are prevalent in many industries, ranging from the food processing and commercial cosmetic sectors to industries such as chemical and oil-refining. Uncontrolled foaming results in product losses, equipment downtime or damage and cleanup costs. To speed up defoaming or enable anti-foaming, liquid oil or hydrophobic particles are usually added. However, such additives may need to be later separated and removed for environmental reasons and product quality. Here, we show that passive defoaming or active anti-foaming is possible simply by the interaction of foam with chemically or morphologically modified surfaces, of which the superamphiphobic variant exhibits superior performance. They significantly improve retraction of highly stable wet foams and prevention of growing dry foams, as quantified for beer and aqueous soap solution as model systems. Microscopic imaging reveals that amphiphobic nano-protrusions directly destabilize contacting foam bubbles, which can favorably vent through air gaps warranted by a Cassie wetting state. This mode of interfacial destabilization offers untapped potential for developing efficient, low-power and sustainable foam and froth management.

The Significance of Hydrophobicity for the Water Retention Properties of Sand and Coal

For mine wastes such as coal tailings, management of these materials requires complex geotechnical engineering that uses many soil properties, such as water retention. However, coal itself is chemically heterogeneous and often appears to be partially hydrophobic, which affects its water retention properties. This study aims to outline how hydrophobic soil particles and coal alter water retention curves compared to hydrophilic materials. The study involves four materials: sand, hydrophobized sand, crushed rock and crushed coal. Mixtures of sand with different proportions of hydrophobic particles had their water retention curves measured and compared, with the only variable being the particle surface characteristics. The rock and coal were separated into different particle size fractions and had their water retention curves measured and compared, with the only variable being particle hydrophobicity. A clear trend was observed for the sand mixtures: the degree of saturation at any suction was reduced when increasing the hydrophobicity of the material. This trend indicates the fundamental water retention behavior expected for soils more hydrophobic than is typical, which was not clearly demonstrated in previous studies. However, a similar trend was not seen when comparing the rock and otherwise identical hydrophobic coal samples, which actually appeared hydrophilic in terms of water retention. ESEM imaging shows a dual hydrophilic and hydrophobic behavior for coal which may explain the result. However, further research is required to understand the discrepancy, which appears to be caused by an unknown coal–water phenomena.

LABORATORY AND PRODUCTION TESTS OF A HYDROPHOBIC ADDITIVE FROM THE GROUP «RAMSINKS-2M» FOR CONCRETE USED FOR THE MANUFACTURE OF STATION BLOCKS AND BLOCKS OF TRANSPLANTING TUNNELS WITH HIGH WATERPROOFING

In the work, conducting experimental works and experiments on the choice of optimal ratios of PTCs 1-100 and hydrophobic material «Ramsinks-2MU», studying hydrophobicity of mixtures, recipes-solutions, research of technological properties of mixtures. Experimentally proved that the brand of concrete is not permeable reached by W12, which can not be obtained by sealing concrete. The results of laboratory tests of concrete with the addition of «Ramsinks-2m» are given. To increase the waterproofing of concrete antiltration barriers, underground structures of buildings and structures, reservoirs, etc. It is proposed to achieve high waterproofing of concrete by adding to its composition of the hydrophobic additive «Ramsinks-2MU». The use of new hydrophobic materials such as "Ramsinks-2MU" for the manufacture of concrete on the construction of the subway in Kyiv - is an exhaust direction in metrobudination. Reliable waterproofing of outflows and openings can be achieved by applying a water-retailing additive "Ramsinks-2MU" and its modifications. Technological simplificence in the introduction of the latest material is achieved by direct use of hydro-insulating works by introducing it in the appropriate ratio in traditional solutions. A method for selecting a percentage of a hydrophobic additive with cement for different classes of concrete and for specific mining-geological conditions has been developed. This technique makes it possible for the latest technologies to determine the qualitative characteristics of the hydrophobic additive offered. The use of this additive in the manufacture of concrete and solutions contributes to an increase in the elasticity of the mixture, prevents the uneven concentration of fillers, as well as prevents mixing of the mixture and increases resistance to aggressive factors. The high waterproofing of products with the additive is achieved with the corresponding concrete composition by fine schedules of hydrophobic particles. By reducing the negative impact of moisture on the design, their durability increases. Laboratory test tests showed that the introduction of a hydrophobic additive "Ramsinks-2M" significantly affects the strength of the cement stone in the hydrophobic mixtures "Ramsinks-2MU". The proposed hydrophobic materials have qualitative advantages over other similar materials, as well as cost-beneficial. They can be used when the seams of tunnel processing and stations, as well as waterproofing of monolithic concrete structures in the subway.

Novel Approach for Fine Ilmenite Flotation Using Hydrophobized Glass Bubbles as the Buoyant Carrier

Ilmenite disseminated grain size is relatively fine, and it must be finely ground to fully separate ilmenite from gangue and then produce fine-grained minerals, which deteriorates flotation. A novel method using buoyant carriers to improve the recovery of fine ilmenite in froth flotation was introduced in this study. Hydrophobized glass bubbles (HGB) as carrier materials were obtained by an efficient, simple modification of ordinary glass bubbles. The carrier flotation of fine ilmenite in the presence of HGB was investigated by micro flotation tests, X-ray diffractometer analysis, Fourier transform infrared (FTIR), optical microscope observation, and the extended DLVO theory (XDLVO). Micro-flotation results showed that the recovery of fine ilmenite in presence of HGB was 37.7% higher than that when using NaOL alone at pH 6. FTIR analysis and optical microscope observation revealed that fine ilmenite particles can be closely attached on the HGB surface to increase apparent particle size considerably. The data calculated from the DLVO theory indicated that the acid–base interaction force determined the adsorption between two hydrophobic particles.

Supramolecular interactions in the mixtures of hydrophobic and hydrophilic pyrogenic silicas

In order to study the peculiarities of the interaction of hydrophobic particles with water, the binding of water in composite systems based on structurally modified mixtures of 1/1 hydrophilic (A-300) and hydrophobic (AM-1-300) silica was studied by low-temperature 1H NMR spectroscopy. It is shown that with equal amounts of hydrophobic and hydrophilic components, the dependence of the interfacial energy on the value of surface hydration has a bell-shaped appearance with a maximum at h = 3000 mg/g. The obtained dependence is explained from the point of view of restructuring of the composite system under the influence of mechanical loads and the possibility of air removal and adsorption processes in the interparticle gaps of hydrophobic and hydrophilic components, as well as the phenomenon of nanocoagulation. Increasing the concentration of the hydrophilic component does not increase the binding energy of water. Under the influence of liquid hydrophobic substances, depending on the bulk density of the composite, there may be an increase or decrease in interfacial energy. The growth is due to the restructuring of the hydrophobic and hydrophilic components (nanocoagulation), and the decrease is due to the displacement of water from the surface into pores of larger radius. For n-decane, the effect of increasing the melting temperature by several tens of degrees was registered in the interparticle gaps.