Papers by Keyword: Venturi Scrubber

Abstract: — Corrosion is prevalent throughout the world, none less so than in the oil and gas industry. Managing and mitigating corrosion in refining complexes is of paramount importance in order to prevent undesirable consequences such as major fires, explosions and Boiling Liquid Expanding Vapor Explosion (BLEVE) due to Loss of Primary Containment caused by the thinning and ultimate failure of pipelines and vessel walls. Analysis of a platformer unit at a Malaysian refinery has identified the occurrence of thermal fatigue and erosion corrosion on the Vent Gas Tower (VGT) Caustic Circulation line, which in turn has led to the excessive degradation of the walls of a venturi scrubber and the 8’’ caustic circulation line with initial thickness of 12.70mm. The rate of corrosion (0.88 mm/year) of the 8’’ caustic circulation line exceeds the standard allowable carbon steel corrosion rate (0.1 mm/year) as stated in API 571 Damage Mechanisms Affecting Fixed Equipment in the Refining Industry. This indicates that the circulation line has significant potential to fail which would lead to a major HSE incident. Based on these findings it is recommended that the refinery in question modifies the line by increasing the thickness of the line and include a cooling system to reduce temperature swing (ΔT) to below 93°C. Besides that, it is suggested that the implementation of Corrosion-Resistant Alloys (CRA) is conducted on the line. According to ASME B31.3 and supported by ASTM A 193, the line can be replaced with nickel-based alloy, alloy 800H and killed carbon steel which have high resistivity to corrosion than carbon steel. However, more comprehensive studies need to be conducted to identify the viable mitigation methods that are suitable to be implemented on the Vent Gas Tower (VGT) Caustic Circulation line.

Abstract: Venturi scrubber is a high-efficiency wet dust collector,and has a high capture efficiency for small solid particles. Applied to metal mines, the venturi scrubber not only eliminate the mine dust in the processes of mining and driving, but also can capture the diesel exhaust particles effectively in theory. Then the air in the mine has been purified and the staff can keep away from the harm of mine dust and diesel exhaust particles. Based on the results of this research from the predecessor, the paper design a reasonable set of pilot programs for mine workers.

Abstract: In nuclear power plant (NPP), particulate matter and gaseous pollutant release into the environment in severe accidents. To prevent from this disaster, filtered vented containment system (FVCS) containing venturi scrubber is being installed. The present work herein is the CFD simulation of throat pressure in venturi scrubber. A commercial software ANSYS CFX tool has been selected for this research. Euler-Euler regime is used to get the picture of behavior of fluid dynamics inside the venturi scrubber. Gas and liquid interact with each other in throat section of venturi scrubber. The pressure at the throat is one of the important factors to analyze the performance of venturi scrubber. In order to verify the results, mesh independency is checked. CFX and experimental results show good agreement with each other. The results obtained from CFX simulation are useful to improve the venturi design.

Abstract: Venturi Scrubbers are used in filtered vented containment system (FVCS) for collection of aerosols produced in NPP in severe accidents. Therefore, venturi scrubber (VS) needs an attention to design it properly and improved in all aspects. In this research, CFD simulations of prediction of pressure drop in venturi scrubber has been carried out. ANSYS CFX tool is used to obtain the simulation results. k-ε turbulence model is employed to study the fluid dynamics of the venturi scrubber. Mesh size plays an important role for convergence and accuracy of results. Therefore, the mesh independency is checked for optimized mesh size.

Abstract: The Venturi scrubber, equipment frequently used in the removal of particles from gases, is constituted basically by a duct with a convergent section followed by a constriction, or throat, and a divergent section. A liquid, usually injected in the throat, is atomized by the flowing air at high speed. The formed droplets act as collectors of particles from the gas. The process of droplet formation from an injected liquid can be described as follows: the liquid enters the gas stream in the form of a jet, perpendicular to the gas flow. As the jet penetrates the gas stream, it is bent by the gas drag. After a given penetration distance, a burst occurs, and the remaining jet is disintegrated as a droplet cloud. Depending on the liquid and gas flow rates, the penetration on the jet into the gas stream may reach the walls of the equipment, and a fraction of liquid deposits in the form of a film. This film contributes little for the removal of particles from the dust laden gas. Few studies have analyzed the formation of film at the scrubber walls and its influence in the droplet size inside the Venturi scrubber. For this reason, the present study is focused on the experimental measurement of the deposition of the liquid film on the walls of a rectangular Venturi scrubber and, simultaneously, the estimation of the droplet size measured in the Venturi throat. The experiments were carried out varying the liquid flow rate, the gas velocity and the number of orifices of liquid injection. A correlation, using a dimensionless number, was proposed to quantify the influence of each experimental condition. The results indicate that film fraction has a significant influence in the droplet size measured inside of Venturi scrubber.

Abstract: A Pease-Anthony Venturi scrubber is a relatively simple and very efficient device used for gas cleaning. This paper presents photographic images of the atomization of a liquid jet in the throat of a Pease-Anthony Venturi scrubber, obtained through the development and use of an electronic flash of short duration. This new evidence was used to improve the parameters of the model of Gonçalves et al. (2000) [1]. The experimental conditions used were: throat gas velocities between 59 and 74m/s, jet velocities between 3.18 and 19.10m/s and liquid injected into the throat through different orifices.

Abstract: The Venturi scrubber, equipment frequently used in the removal of particles from gases, is constituted basically by a duct with a convergent section followed by a constriction, or throat, and a divergent section. A liquid, usually injected in the throat, is atomized by the flowing air at high speed. The formed droplets act as collectors of particles from the gas. The size and the size distribution of the droplets inside the equipment are therefore of great importance in the equipment performance. In the present work, the liquid jet penetration is visualized and the study of the droplet formation in a rectangular Venturi is carried out. The liquid injection is made through multiple orifices and the interaction of multiple jets is taken into account. In the experimental tests, the gas velocity in the throat, the liquid flow rate and the number of orifices for liquid injection were varied. A Malvern Spraytec aerosol analyzer was used for measuring of the droplet size and size distribution. The results showed that the liquid jet penetration influences significantly the size of the formed droplet.

Abstract: The suspended particles in the air are a factor that causes chronic illnesses to the respiratory system, which go from allergy to severe pulmonary damage. Particulary, breathable particles (from 0,5 μm to 5,0 μm sizes) cause damages to the respiratory system. The penetration and the deposition are the reason for the damages to the pulmonary alveolus. The industrial activity is the main responsible for the most part of the breathable particles emission. Because of that, Venturi scrubbers have been incorporated to the industrial process due to their high efficiency for particle collection. Venturi scrubbers are gas-atomizing devices. They are mechanical devices which rely on shearing and impaction forces to break water into fine droplets. Those droplets in contact with the particles, will collected them. This work consists of a Venturi scrubber of circular section operating horizontally, with liquid injection through a single orifice located in the scrubber throat. The experiments will analyse the influence of the length throat, gas velocity, liquid flow and particles sizes on the Venturi´s collection efficiency.

Abstract: The Venturi scrubbers have a high collection efficiency to remove very small particles from gaseous streams. The main purpose of this work is to determine the overall collection efficiency of Venturi scrubbers with circular section under different operation conditions. The experimental system consisted of a Venturi scrubber with circular section and liquid injection in the throat. A factorial experimental design was carried out; the overall collection efficiency was the response. Three variables were analyzed: the throat length, the air velocity and the liquid flow. The best values for efficiency were obtained for 15 m/s of air velocity and 300 mL/min of liquid flow and the throat length did not have influence.