Bench Tests and CFD Simulations of Liquid–Gas Phase Separation Modeling with Simultaneous Liquid Transport and Mechanical Foam Destruction

This paper presents simulation and bench test results for a special type of centrifugal pump that enables the transport of dispersive foaming liquids and simultaneous separation of the liquid phase. During the design phase, CFD (Computer Fluid Dynamics) simulations were performed using Ansys Fluent. The simulations covered changing the operating parameters of the pump (mass/volume flow rate), pressure analysis for the first impeller, and structural optimization of the pump components. In the second stage of the research, the pump and a measuring station were constructed to validate the results of the numerical simulations.

Modeling of Non-Newtonian Flow in an Inverted Cone Foam Breaker

Foam formation is a widespread phenomenon and often a serious problem in fermentation processes. Inverted cones used as mechanical foam breakers are rotating devices that pump the fluid up and pulverize it at the edge. The shearing and centrifugal actions of such geometries can help to control foaming. In this study, a model was developed using Computational Fluid Dynamics (CFD), based on the non-Newtonian properties of foam, to describe and explain the action of inverted cones as foam breakers.

Experimental determination of the rational geometrical parameters of the sprinkler frame arms and deflector on the expansion rate and stability of foam

The results of experimental studies on determination of the effect of the deflector-type sprinkler geometric parameters on the air-mechanical foam formation process are presented in the article. A collapsible sprinkler was developed for the experiment. The elements of the collapsible sprinkler which allow creating its various configurations in a fairly wide range of geometric parameters were made from polylactide (PLA-plastic) with the help of 3D printing. The dependencies of the air-mechanical foam expansion rate and stability on the sprinkler holder length, as well as the external diameter, the taper angle and the ledges height of the sprinkler sprayer were established. The ranges of optimal values along the holder length L = 45÷55 mm and the sprayer ledges height h = 1÷3 mm of the sprinkler for generation of foam with the greatest expansion rate and stability were determined, as well as the ranges of values of these parameters at which the change in the quality characteristics does not occur (L = 90÷150 mm, h = 5÷15 mm). A decrease in the foam quality characteristics with an increase in the sprayer taper angle of the sprinkler was established. Approximate dependencies of the foam expansion rate and stability on the sprayer taper angle of the sprinkler in the range α = 30÷135° were obtained. In addition, it is determined that an increase in the sprayer external diameter in the range from 20 mm to 100 mm results in a gradual deterioration in the foam qua lity. The results of the conducted researches will allow optimizing geometrical parameters of existing designs of deflector-type sprinklers with the aim to increase their fire extinguishing efficiency.

Environmentally Safe Method of Localization of Soil Pollution in Emergency Situations of Technogenic Nature

Puporse. Development a method for the localization of emergencies associated with the leakage of volatile toxic liquids, by using the foams with adjustable curing time. Methods. Surface insulation method of the spilled toxic liquid by using the air-mechanical foam. Results. The results of the development a method for the localization of emergencies associated with the leakage of volatile toxic liquids, by using the foams with adjustable curing time are presented. The new scientific result consists in the use of gelation processes, to obtain an insulating agent with a specified time of curing. It has been established that the most effective means that reduce the rate of transition of toxic liquids to the gas phase are those that ensure the liquid surface isolation. It is proposed to use foam with the time of cure that can be adjust ed. Experimentally determined gel times for two gel forming systems (NH4Cl + Na2O • 2,5SiO2 and (NH4)2SO4+ Na2O ∙ 2,5SiO2). On the basis of the data obtained, the concentrations of the gel formulation and the gelation catalyst with the gel time were selected in the interval of 30-60 s. Conclusions. The developed systems allow to achieve a long process of isolation at a lower specific consumption of components. It is shown that the use of the proposed components in the soil is an environmentally safe process.

EXPERIMETAL INVESTIGATION OF USING GRANULATED FOAMGLASS FOR COOLING THE COMBUSTIBLE LIQUID

Extinguishing of flammable liquids is one of the most difficult problems of firefighting. Especially great difficulties are caused by fire extinguishing of oil and oil products, in tank farms. The best results when extinguishing flammable liquids are provided by means air-mechanical foams. For various types of foams, there are common drawbacks: low foams stability under the action of intense heat fluxes from the flame of a burning liquid, their rapid destruction upon contact with polar liquids, difficulties with feeding over long distances, high cost of a number of foaming agents, the presence in their composition of environmentally hazardous substances, contamination of flammable liquids, high cost of foam supply systems . To eliminate the disadvantages of air-mechanical foam, it is proposed to use granular foam glass as one of the components of the fire extinguishing system for extinguishing flammable liquids. It has been previously established that the foam glass layer slows down the evaporation of combustible liquids. In addition, filling the foam glass leads to the cooling of the burning liquids. Cooling is one of the most important mechanisms for stopping combustion. Due to the cooling of flammable liquids, the vapor pressure is lowered over their surface and, accordingly, the intensity of combustion decreases. To determine the conditions for combustion of flammable liquids need to know the temperature of liquids after exposure to them extinguishant substances.

DEVELOPING OF BLOCKING NOZZLE FOR COMPLEX EXTINGUISHING ON THE INITIAL STAGE OF FIRE

After analyzing the presence of fire and technical equipment, in particular fire extinguishing devices, on the fire and rescue engines of the SES of Ukraineunits, we have suggested, developed and constructed a nozzle for obtaining low-frequency air-mechanical foam. This nozzle can serve as a combination of water and foam extinguishing agents to extinguish fires that have not developed into significant areas and sizes.It is preferable to eliminate the fire at the initial stage of its occurrence, preventing the influence of the effects of its dangerous factors on living creatures and the environment. Given the above problem, the authors designed a nozzle with the ability to completely cease the supply of extinguishing agents, using an overhead crane with a handle.At the exit from the fire nozzle, a metal mesh consisting of 1,5 x 1,5 mm tubes is installed. The shell of the nozzle is equipped with rubber overlays on both sides, which will protect arescuer from possible electric shock. The use of such nozzle allows for more efficient elimination of fires and more economical use of extinguishing agents. The technical characteristics are acceptable for the subsequent successful use of the device as intended. Additionally, one of the advantages is the possibility of ceasing the delivery of extinguishing substances in case of changing the position of a rescuer during the elimination of fire, reducing the flow of water and foam, as well as protection against possible electric shock.