The Experimental Study on Effects of Height and Hold up on performance of Vertical Gas-Liquid Separator using Amin Contactor Tower

In present research, first the treatment of flow in designed vertical gas-liquid separator and Amin contactor tower at refinery in order to reduce of liquid percent was simulated. In order to simulation was used three dimension model with finite volume method numerically. Then separator and contactor tower has been modeled three dimensional and for droplet tracking in continuous phase has been used discrete phase model (DPM) with turbulence RNG k-Ɛ model. Also the gambit software is used for three dimension designs and fluent is used for solution governing equations of flow field. After simulation, the governing model of separator and contactor tower, fluid flow, the effect of growing of liquid droplet, droplet settling length (disengagement time) was studied. After analysis and compare behavior of flow in separator and tower, the results of simulation compared with experimental results at sweetening unit in Sarkhoun and Qeshm gas treating company that has 95% compatibility. The simulation results has shown that TOTAL method has more compatibility with relation to other methods so that one of effective parameters in improvement of separation process is growing of liquid droplets and separation factor depend on that, also more disengagement time causes increase hold up time and finally growing of liquid droplets. Additionally according to younger's comment gas-liquid separators can applied in horizontal or vertical status so that he founded if L/D be 1.7 to 3.6, the separators should be used vertically also Branan has proved that if L/D > 5, a horizontal separator should be used. The results of research are shown that in special conditions with L/D>6.5 can apply vertical separator. Finally experimental data has shown that the settling length can be 36 ft (11m) that separation works well and according to Schiman this length should be 0.75D or a minimum 12in (0.305 m) whereas Gerunda recommends a length equal to the diameter or a minimum of 3 ft (0.914 m) that present result is new recommendation

Current control strategy of grid-connected inverter for distributed generation under nonliner load conditions

Distributed generation (DG) has become more important in recent years for supplementing traditional fossil energy resources for power generation. The DGs include microturbine (MT), fuel cell, photovoltaic (PV) arrays, wind turbine and storage devices. The DG units can operate in parallel to the main grid or in a microgrid (MG) mode. The MG is a discrete energy system consisting of DG and loads that are capable of operating in parallel with, or independently from the main grid. Meanwhile, Grid-Connected Inverters (GCIs) are typically used as the interfaces to connect each DG to the common bus in an MG mode. In the ongoing effort to improve the performance of MG, control strategy of three-phase GCI under nonlinear load conditions has become a mature and well-developed research topic, and some control strategies have been implemented in several countries. A new approach is proposed to control the GCI of DG in an MG under nonlinear and unbalanced load conditions. The proposed control strategy features the synchronous reference frame method. The primary advantage of this method is its ability to effectively compensate for the harmonic current content of the system currents and MG without using any compensation devices, such as an Active Power Filter (APF) or passive filter. In this system, the control strategy is designed to eliminate the main harmonics as well as to cancel the remaining harmonics. Furthermore, correction of the system unbalance is another key feature of the proposed strategy. Fast dynamic response, simple design, stability, and fast transient response are other key features of the presented strategy. The current total harmonic distortions were reduced from above 37.8% to less than 1% with the proposed control strategy under nonlinear load conditions. The proposed control method can be used on the GCI of MT and PV; and has the ability to reduce the complexity, size and cost of the control method in comparison with APFs

Techno-Economic Analysis of Stand-Alone Hybrid Energy System for the Electrification of Iran Drilling Oil Rigs

This paper explores the potential of use of stand-alone hybrid wind/solar energy system in electrification of calibrating equipment of drilling oil rig in Iran. To achieve this, different hybrid energy system configurations based on calibration equipment demand are proposed. This study puts emphasis on the energy production and cost of energy from both wind turbine and photovoltaic (PV) in the hybrid system. In addition, to make conditions more realistic, the real meteorological data is used for HOMER software to perform the technical and economic analysis of the hybrid system. Results indicate that the PV array shares more electricity production than the wind turbine generator if both wind turbine and PV array are utilized in the wind/solar hybrid system. Moreover, results show that the operational cost will be reduced by the suggested hybrid system

Optimal SSSC-based power damping inter-area oscillations using firefly and harmony search algorithms

The static synchronous series compensator (SSSC) can add a series reactance to the transmission line, and when it is fed using auxiliary signals, it can participate in damping inter-area oscillations by changing the series reactance. In this paper, the effect of the SSSC on small-signal stability is investigated. The design of a controller for damping oscillations is designed and discussed. Moreover, using the firefly and the harmony search algorithms, the optimal parameters controlling SSSC are addressed. The effectiveness of these two algorithms and the rate of SSSC participation in damping inter-area oscillation are also discussed. MATLAB software was used to analyse the models and to perform simulations in the time domain. The simulation results on the sample system, in two areas, indicated the optimal accuracy and precision of the proposed controller

The effect of progressive muscle relaxation on anxiety and stress in nursing students at the beginning of the internship program

Background and aims: Anxiety is a complicated process appearing from low to high which may reduce the learning ability. It is common among nurses as they struggle to cope with increasingly complicated stressors such as examinations, article preparation and practical experiences. The aim of this study was to evaluate the effect of muscle relaxation on reduction of anxiety in nursing students before starting the internship program. Methods: In this study, 40 nursing students who were going to start their internship program were randomly divided into two equal groups. Before starting the internship program, all students were asked to fill a questionnaire (Spielberger Test Anxiety) to measure their anxiety. In addition, physiological parameters (blood pressure, pulse, respiration, temperature) were collected before and after the study in both groups. During a 45-min session, muscle relaxation training was given to the test group. Muscle relaxation practice was continued three times per day for two weeks. Two weeks after starting the internship, Spiel Berger Test Anxiety and physiological parameters were collected again in both groups. Data were analyzed using Chi-square and t tests. Results: The average age of the students in both groups was 22.7±2 (range=21 to 25 years) and the majority of the students were female (75%). No significant difference was observed between two groups for willingness to the nursing profession, birth rank and the average scores of the students from the previous years. The average anxiety score in control group before and after the study was 27.5±10.2 and 28.3±8.8 respectively (P>0.05). Average anxiety score in test group before and after the study was 25.4±19.5 and 29.2±14.1 respectively (P<0.05). Conclusion: To alleviate stressors associated with practical practice and create a healthy work environment for practice, it is recommended that nursing students have some progressive muscle relaxation before entering practical environments

Numerical Study of Fluid Flow in Dew Point Setting Unit Separators in Sarkhoun and Qeshm Gas Treating Company

ABSTRACT In this paper, in order to research the effects of separator plates geometry on fluid flow behavior is used from three types of plate with different tips -Round, sharp and flat (main geometry)-for simulation was used 2dimension and 3dimension with numerical finite volume model. Then plate has been modeled 2 dimensional and for purpose of droplet tracking in continuous phase (CH 4 ) has been used discrete phase model (DPM) with turbulence Reynolds stresses model (RSM). Also Gambit software is used for mesh generation and boundary conditions and fluent software is used for solution of governing equations. After simulation, effect of growing of droplet, plate tip geometry, density of liquid droplet in continuous phase, distance between plates and pressure drop was studied. The result of research compared with experimental result in outlet of separator at Sarkhoun and Qeshm gas treating company that has 90% compatibility. The simulation result has shown that plate with flat tip has more compatibility with relation to other plates in that has acceptable pressure drop and separation efficiency. Also effective parameters in improvement of separation process are growing and increase density of liquid droplet that plates with flat tip duo to their special geometry have more compatibility for separation with present condition. The result of research is shown that in applicable condition (Rate of flow and properties of fluid), performance of flat tip plate is better than two other types

A comparison of life style with body mass index (BMI) of loss and more than 25 in individuals between 20-65 years in Shahrekord city

Background and aim: The present study aimed to compare the habits and features of obese (BMI>25) and normal (BM25 kg/m2 then it was designated in the case group (obese). Samples with BMI between 20-25 kg/m2 were assigned into the control (normal) group. The Miller-Smith life style questionnaires were used for both groups. Data were analyzed using Chi-square and t-tests. Results: No significant differences were found between the two groups tested in terms of the mean age, gender, level of education, marital status insurance, the length of sleep during 24 h, cigarette smoking and losing job or spouse. However, a significant relation was found in using vegetables, sausage, fried potatoes, enriched breads, low fat milk, low salt, candies and chocolates (P<0.05). Conclusion: The present study suggests that one way to control obesity and prevent diseases is to ameliorate the life styles with education to people

The effect of heparin after primary percutaneous coronary intervention on short-term clinical outcomes in patients with ST-segment elevation myocardial infarction

Background: Doing percutaneous coronary intervention (PCI) in the first hours of myocardial infraction (MI) is effective in re-establishment of blood flow. Anticoagulation treatment should be prescribed in patients undergoing PCI to decrease the side effects of ischemia. The aim of this study is to determine the effect of heparin prescription after PCI on short-term clinical outcomes in patients with ST-segment elevation myocardial infarction (STEMI). Materials: This randomized clinical trial study was conducted at Imam Ali cardiovascular center at Kermanshah university of medical science (KUMS), Iran. Between April 2019 to October 2019, 400 patients with STEMI which candidate to PCI were enrolled. Patients randomly divided in two groups: intervention group (received 5,000 units of heparin after PCI until first 24 hours, every 6 hours) and control group (did not receive heparin). Data were collected using a checklist developed based on the study's aims. Differences between groups were assessed using independent t-tests and chi-square (or Fisher exact tests).Result: Observed that, mean prothrombin time (PT) (13.30±1.60 vs. 12.21±1.15, p<0.001) and partial thromboplastin time (PTT) (35.30±3.08 vs. 34.41±3.01, p=0.003) were significantly higher in intervention group compared to control group. Thrombolysis in myocardial infarction (TIMI) flow grade 0/1 after primary PCI was significantly more frequently in control group (5.5% vs. 1.0%, p=0.034). The mean of ejection fraction (EF) after PCI (47.58±7.12 vs. 45.15±6.98, p<0.001) was significantly higher in intervention group. Intervention group had a statistically significant shorter length of hospital stay (4.71±1.03 vs. 6.12±1.10, p<0.001). There was higher incidence of re-vascularization (0% vs. 3.0%; p=0.013) and re-MI (0% vs. 2.5%; p=0.024) in the control group.Conclusion: Performing primary PCI with receiving heparin led to improve TIMI flow and consequently better EF. Receiving heparin is associated with lower risk of re-MI and re-vascularization