Tolerable Risk for Hydrogen Sulfide in Sewage Treatment Plant- STP

Hydrogen sulphide is a toxic gas, it can cause a range of physiological responses from simple annoyance to permanent injury and death. There are a number of approaches to deal with the impacts of toxic gases. This study focused on minimizing the hazard exposure for hydrogen sulfide in the different operational zones for activated sludge process in sewage waterplant. Research tools/ approaches conducted were interviews, toxic gas testers, analysis report interpretation & quantitative risk assessment method. The study was conducted on Arabian Peninsula during the period (September 2019- September 2021). The (13) operational locations tested for toxic gas concentrations were inlet chamber, outlet channel, coarse /fine screens, primary sedimentation tank, activated sludge tanks, secondary sedimentation tanks, gas desulfurization unit, disc filters, chlorine dosing unit, sludge dewatering, sludge silos and digester tanks. The study found that the highest concentration for H₂S in the inlet chamber/ outlet channel. The severity hazards in the sewage treatment plant using activated sludge process are the asphyxiation by H₂S was extremely high can cause harm to public health, followed by the radiation hazard followed by electrical hazard, then (working at height, mechanical, traffic, health, chemical, physical, ergonomic, environmental, microbial and natural). The frequency of hazards occurrence is asphyxiation by H₂S was extremely high followed by the radiation hazard and health hazard including the infection with Covid 19 virus followed by mechanical hazard then (electrical, traffic, ergonomic, natural, chemical, physical and natural). Control measures were recommended to minimize the risk of asphyxiation by H₂S in the working environment at the STP.

ANALISIS UNJUK KERJA KOLEKTOR SURYA PELAT DATAR DENGAN PENAMBAHAN SIRIP BERLUBANG BERDIAMETER BEDA SEBAGAI NOSEL YANG DISUSUN SECARA STAGGERED

The solar collector is a device that collects solar radiation and converts it into useful heatenergy. Several types of solar collectors include the parallel flow flat plate solar collector and theperpendicular flow absorber plate solar collector. Previous design of flat plate solar collectorperpendicular flow absorber plate usually uses plates with the same hole diameter. To improve theperformance of this solar collector, modifications have been made by adding perforated fins withdifferent diameters which are arranged staggeredly as an air flow channel or nozzle. The intendedmodification of nozzle diameter is to make the nozzle diameter size different from the large diameter nearthe inlet to the small diameter near the oulet and compared to the reverse nozzle position. Making thediameter of the nozzle near the inlet is larger than the diameter of the hole near the outlet aims to makethe mass flow of air passing through the hole near the inlet larger, so that the flow of air massesexperiences more heat transfer while the diameter of the hole near the outlet is made small is to reducethe mass flow of air which is wasted faster through the outlet channel. With the variation of the holediameter from large to small, it is expected that the heat transfer that occurs in the solar collector will bemore optimal, but it should also be seen in the reverse position. The research was carried outexperimentally. The results of his research show that the useful energy and efficiency of solar collectorswith large to small diameter slotted fins are higher than those with small to large diameter slotted fins.

Study on Water Cooling Performance of IGBT Module in Wind Power Converter

Thermal design of IGBT is the key technology on wind power converter design. This paper introduced a theoretical calculation method of IGBT power loss which is applicable in wind power converter engineering applications. Meantime, the corresponding mathematic model was established. Considering the divergence of application environments as well as the characteristics of water-cooling heat dissipation, simulation models of two different inlet and outlet position radiators were built in Ansys software. And then the cooling capacity of these two types of radiators was analyzed though simulation. According to the simulation results, the ipsilateral inlet and outlet channel mode radiator was selected. After the sample production of the water cooling plate is completed, the experimental platform is built and the sample was verified. Finally, the experiment results indicated the rationality and practicability of the thermal design and simulation, which provided critical references of IGBT water cooling system design. In this paper, the performance of water cooling radiators is studied, which also provides a reference for the design of other high power electronic products.

Investigation of Ecosystem Health of International Meighan Wetland

Background: The aim of this study was to evaluate the ecosystem health of Meighan Wetland of Arak. Methods: To evaluate the Meighan Wetland of Arak, the status of benthic organisms and other parameters, sampling of sediments of the wetland floor was performed at 10 points of the wetland and at 5 replications at each point. Heavy metal pollution, biological, and water quality indices were also evaluated. Then, the map of ecosystem health was prepared. Results: The results showed that except for the nickel, zinc and lead, for other elements and compounds (EC, Na, Cl, Mg, Ca, HCO3, SO4 and TDS), the minimum and maximum values ​​belonged to stations 3 and 6, respectively. In the case of copper, zinc and lead, the lowest concentration was seen in the northwestern part of the wetland and the highest in the western and southeastern parts of the wetland. Conclusion: The high amount of the mentioned elements and compounds in station 6 may be due to the activity of a factory that produces sodium sulfate in the northern part of the wetland, which causes changes in the wetland ecosystem by removing sediments from the wetland floor. The high level of the copper, zinc and lead in the southern part of the wetland can be due to urban and domestic wastewaters that enter the wetland from the southwest of the wetland through the outlet channel of Arak refinery.

Spectral analysis of gas dynamic processes in the inlet system of a piston engine with turbocharger

THE PURPOSE. To carry out a comparative analysis of the spectra of gas-dynamic characteristics of flows in the intake systems of piston engines with and without turbocharging, to assess the degree of influence of the turbocharger on the flow structure in such systems, and also to propose a method for the gas-dynamic improvement of processes in the system under consideration. METHODS. Due to the complexity of the object of research, an experimental approach was taken as a basis. The experiments were carried out on a single-cylinder piston engine model, which could be equipped with a turbocharger. A system for collecting and processing experimental data based on an analog-to-digital converter was used in the study. Data on changes in local values of velocity and static pressure of pulsating flows in the intake system during the engine's operating cycle were obtained using a constant temperature hot-wire anemometer and a fast-acting pressure sensor. Spectral analysis of functions of flow velocity and pressure versus time was carried out on the basis of the fast Fourier transform algorithm.RESULTS. The article presents a comparative analysis of the spectra of the amplitudes of the velocity and pressure pulsations in the intake system of an engine with and without turbocharging. Also proposed is a method for stabilizing the pulsating flow in the intake system by installing a leveling grid in the outlet channel of the turbocharger compressor. CONCLUSION. It is shown that the installation of a turbocharger leads to a significant change in the structure of gas flows in the intake system of the engine. It has been established that the presence of a leveling grid in the intake system of a turbocharged piston engine leads to a decrease in the low-frequency amplitudes of the flow velocity and pressure pulsations up to 30%. It is shown that the probability of failure-free operation of an automobile engine (cylinder diameter – 82 mm, piston stroke – 71 mm) increases by almost 1% when a leveling grille is used in the intake system.

The Influence of Bulb Position on Hydraulic Performance of Submersible Tubular Pump Device

In order to study the influence of the position of the bulb on the hydraulic performance of asubmersible tubular pump device, based on a large-scale pumping station, two schemes—involving a front-mounted bulb and a rear-mounted bulb, respectively—were designed. The front-mounted scheme uses the GL-2008-03 hydraulic model and its conventional guide vane, while the rearmounted scheme uses the optimized design of a diffuser vane. The method of combining numerical simulation and experimental testing was used to analyze the differences between the external and internal characteristics of the two schemes. The results show that, under the condition of reasonable diffusion guide vane design, the efficiency under the rear-mounted scheme is higher than that under the front-mounted scheme, where the highest efficiency difference is about 1%. Although the frontmounted bulb scheme reduces the hydraulic loss of the bulb section, the placement of the bulb on the water inlet side reduces the flow conditions of the impeller. Affected by the circulation of the guide vane outlet, the hydraulic loss of the outlet channel is greater than the rear-mounted scheme. The bulb plays a rectifying function when the bulb is placed behind, which greatly eliminates the annular volume of the guide vane outlet, and the water outlet channel has a smaller hydraulic loss. In the front-mounted scheme, the water flow inside the outlet channel squeezes to the outer wall, causing higher entropy production near the outer wall area. The entropy production of the rear-mounted scheme is mainly in the bulb section and the bulb support. This research can provide reference for the design and form selection of a submersible tubular pump device, which has great engineering significance.

Development of a new design and model study of functioning of catapult for ladle sliding gate

Sometimes commencement of steel casting at CCM can’t be ensured in a regular mode because of formation of a crust above the nuzzle inlet. The crust can withstand the 3–5 m metal column weight. Design features of facilities, developed by foreign firms for the commencement of technological metal pouring from a ladle without application of oxygen considered, their drawbacks noted. Results of theoretical and experimental studies of strength indices of the solidified layer presented. The layer minimal thickness was also defined, which requires external action on it to ensure free pouring of liquid metal from steel ladles of various volumes. Obtained calculation and experiment data were used to justify design parameters of new catapult power elements. It was shown that the proposed catapults enable considerably decrease manufacturing costs comparing with the known foreign analogs. Besides, operation costs can be also decreased due to multiple application of most of components, thanks to their location outside the outlet channel of ladle sliding gate. For practical utilization two variants of the catapult power block design were recommended, which account particular conditions of sliding gate operation.

Smart Facility Advanced Separator

The objective of this work was to develop the prototype unit of Advanced Production Separator (APS) for simultaneous removal of sand, out from production separator. APS unit was fabricated with size Diameter × Length: 1 × 2 m. System controlling of rotational blades impellers was installed at the bottom section of separator, to prevent sand accumulation at bottom of separator while on-service. This facility will help in preventing of sand accumulation in the separator, leading to minimize period of separator downtime during annual maintenance period, and allowing more working volume for open fluid reservoir to gas-oil phase production separator. Moreover, this will minimize working period for worker going inside the separator for sand clean-out, as a concern of working in the confine space. The optimum conditions for separation of sand and crude oil will be examined, with Computational Fluid Dynamics (CFD) model simulation to observe hydrodynamic flow, relating the experimental conditions. The effects of size of 1) Imperller shapes (model A, B, and C), and 2) Rotational speed of impellers (0, 50, 100, 150, and 200 rpm) were investigated to determine the optimal conditions for APS system. In this work, experimental test run result were compared with CFD simulation result. The optimum conditions for prototype APS unit (800 Litres capacity) is Fan C impeller shape for 5 items, and rotation speed for 150 rpm. This result shows the percentage of sand removal reaching to about 70%. The highest amount of sand in water outlet was found at this optimal condition, corresponding with the small part of sand dune at the bottom of the separator after impellers were driving sand to the outlet channel. From the test run, it was found that experimental results, and CFD simulation are consistent. CFD simulation result can be applied as a first screening to forecast sand removal pattern. This research illustrate the alternative novel solution for solving sand production accumulation problem in production separator, by instantly clear sand out while crude oil operation was on-going. In the future phase, CFD simulation will be further used as a first step for predicting result before separator scale-up. Separator will be experimented with 4-phases (oil, water, gas, and sand), and further expand for 4X of the original size to see an effect of scale-up. Aim to unlock high potential field, by reducing downtime of the separation during sand cleaning, and providing more working volume of separator after sand was removed out from self-cleaning separator.

Development of vibration system for decreasing of intensity of steel ladle outlet channel tightening

The problem of tightening of outlet channel of steel ladle still remains relevant at present. A review of scientific and technical studies, aimed at elaboration of methods to keep the channel flow section constant presented. An analysis of deposition forming mechanisms on walls of outlet channel of steel ladle was done. To prevent their formation it was proposed to apply a vibration impact on the ladle shutter. Using simulation studies and specially elaborated methodology, the degree of influence and frequency of amplitude oscillations, acting along the ladle channel, on increasing speed of layer thickness formation on its walls and number of tearing off hard particles was established. To evaluate intensity of elastic waves absorption by the refractories of ladle shutter during vibration impact on it, a natural experiment was done. As a result of the experiment an initial information was obtained for determining parameters of oscillation process to guarantee effective functioning of the proposed casting facility. A necessity was established to account tenfold decrease of vibration acceleration during propagation of elastic wave along the casting channel from the lower end of collector nuzzle to the upper end of the ladle casting nozzle. Results of the complex studies became base of technical solution at elaboration of design of the ladle shutter. The elaborated shutter is equipped by a system of exciting vertically-directed oscillations, promoting decreasing intensity of hard particles sticking on the walls of the outlet channel. The design of the perfected ladle shutter and general view of its test model shown, which is equipped with the vertically-directed oscillations exciting system. Depending on capacity of the steel ladles, which can be from 100 to 300 t, their shutters can be equipped with one or several pneumatic plunger vibrators. Each of the plunger having the mass of 0.8 kg, can develop an impact force up to 300 N when supplying into its working cavity compressed air of 0.2 MPa pressure at flow rate 150 l/min. Industrial tests of the modernized shutter in a foundry shop of Yasinovatsky machine-building plant were done.

Liquid Mixing Based on Electrokinetic Vortices Generated in a T-Type Microchannel

This article proposes a micromixer based on the vortices generated in a T-type microchannel with nonuniform but same polarity zeta potentials under a direct current (DC) electric field. The downstream section (modified section) of the outlet channel was designed with a smaller zeta potential than others (unmodified section). When a DC electric field is applied in the microchannel, the electrokinetic vortices will form under certain conditions and hence mix the solution. The numerical results show that the mixing performance is better when the channel width and the zeta potential ratio of the modified section to the unmodified section are smaller. Besides, the electrokinetic vortices formed in the microchannel are stronger under a larger length ratio of the modified section to the unmodified section of the outlet channel, and correspondingly, the mixing performance is better. The micromixer presented in the paper is quite simple in structure and has good potential applications in microfluidic devices.