Design and Testing of Apparatus for Producing Dry Fog

Dry fog is a specific form of aerosol that is used in many branches of industry and many aspects of everyday life. It can be used, inter alia, to disinfect rooms or to control the level of humidity. One of its greatest advantages is undoubtedly its ability to work in the vicinity of electrical devices. Although the process of its formation and the very phenomenon of its occurrence are extremely simple things to describe, there are still many aspects that can be discovered, which are the focus of research by scientists around the world. One of the main parameters that influence the production process of dry fog is the pressure of the supplied gas, as well as the environmental conditions in which the aerosol is formed. This work focuses on the production of dry fog with the use of the designed and constructed apparatus, the structure of which is based on a jet nebulizer. The test and measurement stand is equipped with a compressor with a built-in pressure gauge for reading air pressure, a valve that allows the flow to be regulated, and an air supply and heating device that operates at various power values. The aim of this research was to check the impact of the power that is supplied to the system, as well as the impact of changing selected parameters such as gas pressure (which is one of the required media), on the liquid spraying process. The analysis of the results obtained during the experimental tests was based on the photographic method and allowed the mean Sauter volume–surface diameters of the obtained droplets to be compared. The analysis also showed that an increase in the power of the air supply and heating device translates directly into an increase in the ambient temperature in which the dry fog is formed, and contributes to the reduction of the diameter of the generated droplets. Changing the pressure of the atomized gas has a direct impact on the size of droplets in the generated aerosol—the higher the pressure, the smaller the droplets

Influence of Effluent Quality from Sludge Dewatering on Electricity Consumption

During the dewatering process, centrate is produced, which is returned to the beginning of the technological system. The quality of the resulting centrate, and therefore the size of the returned load of pollutants, affects the demand for electricity in the process of biological wastewater treatment. The following study presents the results of centrate quality tests at five wastewater treatment plants located in Poland. The dependence between suspended solids content and ammonia and COD concentrations in the centrate was determined. It was estimated that an increase in the overall suspended solids leads to an increase in COD by about 1.15 kgCOD/kgTSS. No correlation was found between TSS concentration and ammonia. It was calculated that the complete elimination of suspended solids from the sludge would reduce the electricity consumption for all five objects by about 535 MWh/y

Analysis of the dedusting process in a rectangular chamber filter

Purifying air from dust is a very important, current topic. There are many methods to minimize the amount of dust, one of them being chamber filters. This paper presents the research results of a newly designed rectangular chamber filter. The efficiency of the dedusting process is influenced by contamination properties, but also by the construction of the apparatus, inlet, and outlet location, the ratio of certain dimensions, and the gas flow rate. The airflow containing solid particles is a multi-phase, difficult-to-describe issue, therefore an attempt to determine the trajectory of particle movement in the apparatus was carried out using the PIV method. A decrease in the dedusting efficiency was observed with the increase of the gas flow rate, as well as for smaller diameters of the solid particles. The obtained values of the efficiency of the apparatus are comparable with the values obtained for the constructions discussed in other papers

Improvement of Mathematical Model for Sedimentation Process

In this article, the fractional-order differential equation of particle sedimentation was obtained. It considers the Basset force’s fractional origin and contains the Riemann–Liouville fractional integral rewritten as a Grunwald–Letnikov derivative. As a result, the general solution of the proposed fractional-order differential equation was found analytically. The belonging of this solution to the real range of values was strictly theoretically proven. The obtained solution was validated on a particular analytical case study. In addition, it was proven numerically with the approach based on the S-approximation method using the block-pulse operational matrix. The proposed mathematical model can be applied for modeling the processes of fine particles sedimentation in liquids, aerosol deposition in gas flows, and particle deposition in gas-dispersed systems

Flow Rate Control by Means of Flow Meter and PLC Controller

This paper presents a design of a flow meter based on a programmable logic controller (PLC). The new construction of a flow meter controlled by PLC increases the possibilities for the control and automation of fluid flow. Additionally, the didactic potential of the use of simple automation in the form of a programmable logic controller was considered. A device enabling the measurement of fluid flow rate based on a PLC controller was designed, constructed, and tested. The choice of device was the Gems Sensors FT-210 series turbine flow sensor, which is characterized by low purchase and maintenance costs. The properties and the chemical resistance of polyamide-12, the material the sensor is made of, make it possible to test the flow of various types of fluids. As part of the work, an algorithm and a program controlling the device was developed based on the APB Soft software, enabling the accurate reading of the number of impulses sent by the turbine flow sensor. The results of the designed flow meter were compared with the results obtained for the Krohne VA-40 high accuracy rotameter

State-of-the-Art Review of Effervescent-Swirl Atomizers

This paper presents issues in the field of theory, construction, calculations, as well as the design of effervescent-swirl atomizers. The results of experimental studies of spraying liquids with different physico-chemical properties for this type of atomizers are discussed. Effervescent-swirl atomization is a complex process and its mechanism is not fully understood. Therefore, the purpose of the manuscript is the complexity of the atomization process and its mechanism as well as the influence of individual parameters on its efficiency were thoroughly analyzed. The analyzed parameters include: atomizer design, outlet shape, gas and liquid flow rate, injection pressure, physicochemical properties of the atomized liquid, pressure drop, outflow coefficient, spray angle, quantitative droplet distributions, and average droplet diameter. Moreover, in the work, on the basis of the literature review, the results of the research related to, inter alia, the phenomenon of air core formation and the influence of a number of parameters on the efficiency of the atomization process are analyzed. The literature review included in the work makes it possible to better understand the atomization process carried out in effervescent-swirl atomizers, and also provides better design criteria and analysis of the efficiency of the tested devices. The article presents correlation equations covering the basic features of the atomization process, which relate a large number of parameters influencing the efficiency of this process and the character of the sprayed liquid, which may be useful in design practice

Efficiency of Diclofenac Removal Using Activated Sludge in a Dynamic System (SBR Reactor) with Variable Parameters of pH, Concentration, and Sludge Oxygenation

Recently, traditional wastewater treatment systems have not been adapted to remove micropollutants, including pharmaceutical substances, which, even at low concentrations, cause adverse changes in aquatic and terrestrial living organisms. The problem of drug residues in the environment has been noticed; however, no universal legal regulations have been established for concentrations of these compounds in treated wastewater. Hence, the aim of the article was to determine the possibility of increasing the efficiency of diclofenac removal from activated sludge using the designed SBR reactor. This study included six cycles, working continuously, where each of them was characterized by changing conditions of pH, oxygenation, and composition of the synthetic medium. In each cycle, three concentrations of diclofenac were analyzed: 1 mg/L, 5 mg/L, 10 mg/L for the hydraulic retention time (HRT) of 4 d and the sludge retention time (SRT) of 12 d. The highest removal efficiency was achieved in the first test cycle for pH of natural sediment at the level of 6.7–7.0 (>97%), and in the third test cycle at pH stabilized at 6.5 (>87%). The reduced content of easily assimilable carbon from synthetic medium indicated a removal of >50%, which suggests that carbon in the structure of diclofenac restrained microorganisms to the rapid assimilation of this element. Under half-aerobic conditions, the drug removal effect for a concentration of 10 mg/L was slightly above 60%

The Two-Phase Conical Swirl Atomizers: Spray Characteristics

This paper presents the results of experimental studies on two-phase conical swirl atomizers. The impact of various atomizer geometries and different operational parameters of the atomization process on the spray characteristics was investigated. The influence of the mixing chamber height HS to diameter DS ratio and the volumetric flow rates of liquid and gas on the discharge coefficient values, spray angle, droplet size expressed by Sauter mean diameter D32, volumetric and radial distributions of droplet diameters in the spray stream were determined. The analysis of results showed that the discharge coefficient values depend on the Reynolds number for liquid and gas and the atomizer geometry. The spray angle increases as the flow rate of liquid and gas increases depending on the applied atomizer construction. The Sauter mean diameter value is correlated with the geometric dimensions of the atomizer swirl chamber. The rapid increase in D32 occurs after exceeding the value HS/DS ≈ 3. The Sauter mean diameter also depends on the operating parameters. A central area of stream is filled with smaller sized droplets as the gas flow rate increases

Evaluation of the Possibility of Using 1.4462 and 1.4501 Steel as a Construction Material for Apparatus Operating at an Increased Temperature and with Corrosive Factors

The objective of this study was to determine the requirements for steels used as construction materials for chemical apparatus operating at an elevated temperature and to correlate them with the properties of the tested steels. The experimental part examined the influence of the annealing process on the structure and properties of X2CrNiMoN22-5-3 (1.4462) and X2CrNiMoCuWN25-7-4 (1.4501) steel. Heat treatment was carried out on the tested samples at a temperature of 600 °C and 800 °C. Changes were observed after the indicated time intervals of 250 and 500 h. In order to determine the differences between the initial state and after individual annealing stages, metallographic specimens were performed, the structure was analyzed using an optical microscope and the micro-hardness was measured using the Vickers method. Potentiostatic tests of the samples were carried out to assess the influence of thermal process parameters on the electrochemical properties of the passive layer. An increase in the hardness of the samples was observed with increasing temperature and annealing time, the disappearance of magnetic properties for both samples after annealing at the temperature of 800 °C, as well as a significant deterioration in corrosion resistance in the case of treatment at a higher temperature

Determination of twist drill bits wear: the effect of the composition and structure of the steels

The aim of the study was to relate the infl uence of the chemical composition, structure, and basic properties as hardness of the tested drill bits on resistance to their wear. The chemical composition of the drill bit was investigated using the electric excitation emission spectrometry method and EDS microanalysis. Metallographic specimens were prepared and observed to determine the structure of each tool. Hardness tests were carried out on the shank and the working part of the tools. Material wear tests were carried out on the basis of measuring the wear of the drill bit flank. It has been shown that the appropriate selection of the chemical composition and heat treatment has a signifi cant impact on the wear resistance of cutting tools, which directly translates into their quality