scholarly journals Efficient Dewatering of Slimes and Sludges with a Bubble Column Evaporator

Substantia ◽  
2021 ◽  
pp. 89-94
Author(s):  
Mohammad Ziaee ◽  
Mojtaba Taseidifar ◽  
Richard M. Pashley ◽  
Barry W. Ninham
Keyword(s):  
Water Vapour ◽  
Gas Flow ◽  
Bubble Column ◽  
Collection Efficiency ◽  
Pure Water ◽  
Helium Atoms ◽  
Hot Gas ◽  
Quality Water ◽  
Maintenance Process ◽  
Concentrated Dispersion

The recalcitrant nightmare of de-watering slime/sludge is a major issue, for both industry and the environment. A simple process is developed that solves the problem. It uses a bubble column evaporator (BCE) with heated dry air. The model slime to illustrate the de-watering process was a concentrated dispersion of spherical 5 micron silica particles in pure water. Typical slime samples were de-watered in the range 20-35% colloid/water (w/w) using dry inlet gases pre-heated to temperatures of 150°C and 250°C. The BCE process was run at sub-boiling temperatures, with the column solution in the range, 43°C and 74°C, with those two inlet temperatures operating for de-watering the slime. A significant bonus is that the pure water vapour produced can be condensed and used as a source of high-quality water for reuse. The BCE process offers simplicity, resilience to slime feed quality, and a pure water biproduct. It also offers a continuous and controlled low-maintenance process. These are clear advantages in de-watering a wide variety of industrial slimes and sludges. In addition, the process involves the passage of a continuous flow of hot dry gases. This causes the dispersion to remain sufficiently fluid to allow easy transportation. However, once the hot gas flow ceased, the dispersion immediately solidified. The success of the bubble column process for dewatering and validation of the mechanism is even more enhanced if helium is used instead of air. It appears that hot helium atoms can disrupt water hydrogen-bonding in the liquid surrounding the hot bubbles and this enhances water vapour collection efficiency. The bubble method appears to offer more than significant advantages over other methods, such as hydrocyclone methods, which are often used to de-water mining wastes.

Introducing a New Test Rig for Film Cooling Measurements With Realistic Hole Inflow Conditions

2017 ◽  
Author(s):  
Marc Fraas ◽  
Tobias Glasenapp ◽  
Achmed Schulz ◽  
Hans-Jörg Bauer
Keyword(s):  
Film Cooling ◽  
Gas Flow ◽  
Test Rig ◽  
Hot Gas ◽  
Cooling Hole ◽  
Measurement Principle ◽  
Density Ratios ◽  
Operational Range ◽  
Film Cooling Holes

Further improvements in film cooling require an in-depth understanding of the influencing parameters. Therefore, a new test rig has been designed and commissioned for the assessment of novel film cooling holes under realistic conditions. The test rig is designed for generic film cooling studies. External hot gas flow as well as internal coolant passage flow are simulated by two individual flow channels connected to each other by the cooling holes. Based on a similarity analysis, the geometry of the test rig is scaled up by a factor of about 20. It furthermore offers the possibility to conduct experiments at high density ratios and realistic approach flow conditions at both cooling hole exit and inlet. The operational range of the new test rig is presented and compared to real engine conditions. It is shown that the important parameters are met and the transfer-ability of the results is ensured. Special effort is put onto the uniformity of the approaching hot gas flow, which will be demonstrated by temperature and velocity profiles. A first measurement of the heat transfer coefficient without film cooling is used to demonstrate the quality of the measurement principle.

Electrohydrodynamic gas flow in a positive polarity wire-plate electrostatic precipitator and the related dust particle collection efficiency

2006 ◽  
Vol 64 (3-4) ◽  
pp. 259-262 ◽  
Author(s):  
Janusz Podliński ◽  
Jarosław Dekowski ◽  
Jerzy Mizeraczyk ◽  
Drazena Brocilo ◽  
Jen-Shih Chang
Keyword(s):  
Dust Particle ◽  
Gas Flow ◽  
Electrostatic Precipitator ◽  
Collection Efficiency ◽  
Positive Polarity ◽  
Particle Collection

scholarly journals Experimental Research of Gaseous Emissions Impact on the Performance of New-Design Cylindrical Multi-Channel Cyclone with Adjustable Half-Rings

2022 ◽  
Vol 14 (2) ◽  
pp. 902
Author(s):  
Aleksandras Chlebnikovas ◽  
Dainius Paliulis ◽  
Kristina Kilikevičienė ◽  
Artūras Kilikevičius
Keyword(s):  
Experimental Research ◽  
Gas Flow ◽  
Collection Efficiency ◽  
Fine Particulate Matter ◽  
Air Flow ◽  
Gaseous Emissions ◽  
Channel System ◽  
Flow Parameters ◽  
The Impact ◽  
Channel Type

Cyclones are widely used for separating particles from gas in energy production objects. The efficiency of conventional centrifugal air cleaning devices ranges from 85 to 90%, but the weakness of many cyclones is the low collection efficiency of particles less than 10 μm in diameter. The novelty of this work is the research of the channel-type treatment device, with few levels adapted for precipitation of fine particulate matter, acting by a centrifugal and filtration principle. Many factors have an impact on cyclone efficiency—humidity, temperature, gas (air) composition, airflow velocity and etc. Many scientists evaluated only the effect of origin and size of PM on cyclone efficiency. The effect of gas (air) composition and temperature, and humidity on the multi-channel cyclone-separator efficiency still demands contributions. Complex theoretical and experimental research on air flow parameters and the efficiency of a cylindrical eight-channel system with adjustable half-rings for removing fine-dispersive particles (<20 μm) was carried out. The impact of air humidity and temperature on air flow, and gaseous smoke components on the removal of wood ashes was analyzed. The dusty gas flow was regulated. During the experiment, the average velocity of the cyclone was 16 m/s, and the temperature was 20–50 °C. The current paper presents experimental research results of wood ash removal in an eight-channel cyclone and theoretical methodology for the calculation of airflow parameters and cyclone effectiveness.

scholarly journals CO2 Adsorption Capacity of Organic Alkali Sorbent CPEI from Polyethyleneimine

2021 ◽  
Vol 2021 ◽  
pp. 1-18
Author(s):  
Feng Wang ◽  
Lu Yu ◽  
Youhua Li ◽  
Dengfa Huang
Keyword(s):  
Co2 Capture ◽  
Gas Flow ◽  
Bubble Column ◽  
Breakthrough Curves ◽  
Bubble Column Reactor ◽  
Diffusion Resistance ◽  
Order Kinetic ◽  
Order Kinetic Model ◽  
Co2 Adsorption Capacity ◽  
Temperature Swing Adsorption

Support-free cross-linked polyethyleneimine sorbent (CPEI) for CO2 capture was evaluated as the regenerable sorbent. The total amines available for the CO2 capture on CPEI were determined by the polyethyleneimine/glutaraldehyde ratio for the synthesis of CPEI. The CO2 capacity of CPEI in the slurry bubble column reactor reached 4.92 mmol/g, which is 1.97 times higher than that obtained under anhydrous conditions. The adsorption kinetics of CPEI in the reactor were investigated in terms of the CPEI amount, the CO2 fraction, the gas flow rate, temperature, and the total amines available. The experimental breakthrough curves for the sorbent were well-fitted with a fractional-order kinetic model. The modeling analysis found the influence of diffusion resistance on the adsorption is more significant than that of the driving force. The CO2 capacity of CPEI remained almost constant during the temperature swing adsorption/desorption cycles.

Modeling of hot gas flow through a feed stream within a horizontal pipe

2003 ◽  
Vol 32 (6) ◽  
pp. 553-565
Author(s):  
G.X. Hu ◽  
W. Xu ◽  
Y.Q. Liu
Keyword(s):  
Gas Flow ◽  
Feed Stream ◽  
Horizontal Pipe ◽  
Hot Gas ◽  
Flow Through

The Influence of Different Rim Seal Geometries on Hot-Gas Ingestion and Total Pressure Loss in a Low-Pressure Turbine

2010 ◽  
Author(s):  
P. Schuler ◽  
W. Kurz ◽  
K. Dullenkopf ◽  
H.-J. Bauer
Keyword(s):  
Pressure Loss ◽  
Total Pressure ◽  
Gas Flow ◽  
Low Pressure ◽  
Total Pressure Loss ◽  
Pressure Loss Coefficient ◽  
Low Pressure Turbine ◽  
Hot Gas ◽  
Flow Through ◽  
Total Pressure Loss Coefficient

In order to prevent hot-gas ingestion into the rotating turbo machine’s inside, rim seals are used in the cavities located between stator- and rotor-disc. The sealing flow ejected through the rim seal interacts with the boundary layer of the main gas flow, thus playing a significant role in the formation of secondary flows which are a major contributor to aerodynamic losses in turbine passages. Investigations performed in the EU project MAGPI concentrate on the interaction between the sealing flow and the main gas flow and in particular on the influence of different rim seal geometries regarding the loss-mechanism in a low-pressure turbine passage. Within the CFD work reported in this paper static simulations of one typical low-pressure turbine passage were conducted containing two different rim seal geometries, respectively. The sealing flow through the rim seal had an azimuthal velocity component and its rate has been varied between 0–1% of the main gas flow. The modular design of the computational domain provided the easy exchange of the rim seal geometry without remeshing the main gas flow. This allowed assessing the appearing effects only to the change of rim seal geometry. The results of this work agree with well-known secondary flow phenomena inside a turbine passage and reveal the impact of the different rim seal geometries on hot-gas ingestion and aerodynamic losses quantified by a total pressure loss coefficient along the turbine blade. While the simple axial gap geometry suffers considerable hot-gas ingestion upstream the blade leading edge, the compound geometry implying an axial overlapping presents a more promising prevention against hot-gas ingestion. Furthermore, the effect of rim seals on the turbine passage flow field has been identified applying adequate flow visualisation techniques. As a result of the favourable conduction of sealing flow through the compound geometry, the boundary layer is less lifted by the ejected sealing flow, thus resulting in a comparatively reduced total pressure loss coefficient over the turbine blade.

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